Merge branch 'for-next' of git://gitorious.org/kernel-hsi/kernel-hsi

Pull HSI (High Speed Synchronous Serial Interface) framework from Carlos Chinea:
 "The High Speed Synchronous Serial Interface (HSI) is a serial
  interface mainly used for connecting application engines (APE) with
  cellular modem engines (CMT) in cellular handsets.

  The framework is currently being used for some people and we would
  like to see it integrated into the kernel for 3.3.  There is no HW
  controller drivers in this pull, but some people have already some of
  them pending which they would like to push as soon as this integrated.
  I am also working on the acceptance for an TI OMAP one, based on a
  compatible legacy version of the interface called SSI."

Ok, so it didn't get into 3.3, but here it is pulled into 3.4.

Several people piped up to say "yeah, we want this".

* 'for-next' of git://gitorious.org/kernel-hsi/kernel-hsi:
  HSI: hsi_char: Update ioctl-number.txt
  HSI: Add HSI API documentation
  HSI: hsi_char: Add HSI char device kernel configuration
  HSI: hsi_char: Add HSI char device driver
  HSI: hsi: Introducing HSI framework

16 files changed, 1932 insertions, 0 deletions

diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index 9c27e5125dd..7514dbf0a67 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -446,4 +446,21 @@ X!Idrivers/video/console/fonts.c
 !Edrivers/i2c/i2c-core.c
   </chapter>
 
+  <chapter id="hsi">
+     <title>High Speed Synchronous Serial Interface (HSI)</title>
+
+     <para>
+        High Speed Synchronous Serial Interface (HSI) is a
+        serial interface mainly used for connecting application
+        engines (APE) with cellular modem engines (CMT) in cellular
+        handsets.
+
+        HSI provides multiplexing for up to 16 logical channels,
+        low-latency and full duplex communication.
+     </para>
+
+!Iinclude/linux/hsi/hsi.h
+!Edrivers/hsi/hsi.c
+  </chapter>
+
 </book>
diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index 3b7488fc337..e34b531dc31 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -225,6 +225,7 @@ Code  Seq#(hex)	Include File		Comments
 'j'     00-3F   linux/joystick.h
 'k'     00-0F   linux/spi/spidev.h      conflict!
 'k'     00-05   video/kyro.h            conflict!
+'k'     10-17   linux/hsi/hsi_char.h    HSI character device
 'l'     00-3F   linux/tcfs_fs.h         transparent cryptographic file system
                                         <http://web.archive.org/web/*/http://mikonos.dia.unisa.it/tcfs>
 'l'     40-7F   linux/udf_fs_i.h        in development:
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 6f0459cb745..d236aef7e59 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -50,6 +50,8 @@ source "drivers/i2c/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/hsi/Kconfig"
+
 source "drivers/pps/Kconfig"
 
 source "drivers/ptp/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index 262b19d6b62..95952c82bf1 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_ATA)		+= ata/
 obj-$(CONFIG_TARGET_CORE)       += target/
 obj-$(CONFIG_MTD)               += mtd/
 obj-$(CONFIG_SPI)               += spi/
+obj-y                           += hsi/
 obj-y                           += net/
 obj-$(CONFIG_ATM)               += atm/
 obj-$(CONFIG_FUSION)            += message/
diff --git a/drivers/hsi/Kconfig b/drivers/hsi/Kconfig
new file mode 100644
index 00000000000..d94e38dd80c
--- /dev/null
+++ b/drivers/hsi/Kconfig
@@ -0,0 +1,19 @@
+#
+# HSI driver configuration
+#
+menuconfig HSI
+        tristate "HSI support"
+        ---help---
+          The "High speed synchronous Serial Interface" is
+          synchronous serial interface used mainly to connect
+          application engines and cellular modems.
+
+if HSI
+
+config HSI_BOARDINFO
+        bool
+        default y
+
+source "drivers/hsi/clients/Kconfig"
+
+endif # HSI
diff --git a/drivers/hsi/Makefile b/drivers/hsi/Makefile
new file mode 100644
index 00000000000..9d5d33f90de
--- /dev/null
+++ b/drivers/hsi/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for HSI
+#
+obj-$(CONFIG_HSI_BOARDINFO)     += hsi_boardinfo.o
+obj-$(CONFIG_HSI)               += hsi.o
+obj-y                           += clients/
diff --git a/drivers/hsi/clients/Kconfig b/drivers/hsi/clients/Kconfig
new file mode 100644
index 00000000000..3bacd275f47
--- /dev/null
+++ b/drivers/hsi/clients/Kconfig
@@ -0,0 +1,13 @@
+#
+# HSI clients configuration
+#
+
+comment "HSI clients"
+
+config HSI_CHAR
+        tristate "HSI/SSI character driver"
+        depends on HSI
+        ---help---
+          If you say Y here, you will enable the HSI/SSI character driver.
+          This driver provides a simple character device interface for
+          serial communication with the cellular modem over HSI/SSI bus.
diff --git a/drivers/hsi/clients/Makefile b/drivers/hsi/clients/Makefile
new file mode 100644
index 00000000000..327c0e27c8b
--- /dev/null
+++ b/drivers/hsi/clients/Makefile
@@ -0,0 +1,5 @@
+#
+# Makefile for HSI clients
+#
+
+obj-$(CONFIG_HSI_CHAR)  += hsi_char.o
diff --git a/drivers/hsi/clients/hsi_char.c b/drivers/hsi/clients/hsi_char.c
new file mode 100644
index 00000000000..88a050df238
--- /dev/null
+++ b/drivers/hsi/clients/hsi_char.c
@@ -0,0 +1,802 @@
+/*
+ * HSI character device driver, implements the character device
+ * interface.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Andras Domokos <andras.domokos@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/kmemleak.h>
+#include <linux/ioctl.h>
+#include <linux/wait.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/uaccess.h>
+#include <linux/scatterlist.h>
+#include <linux/stat.h>
+#include <linux/hsi/hsi.h>
+#include <linux/hsi/hsi_char.h>
+
+#define HSC_DEVS                16 /* Num of channels */
+#define HSC_MSGS                4
+
+#define HSC_RXBREAK             0
+
+#define HSC_ID_BITS             6
+#define HSC_PORT_ID_BITS        4
+#define HSC_ID_MASK             3
+#define HSC_PORT_ID_MASK        3
+#define HSC_CH_MASK             0xf
+
+/*
+ * We support up to 4 controllers that can have up to 4
+ * ports, which should currently be more than enough.
+ */
+#define HSC_BASEMINOR(id, port_id) \
+                ((((id) & HSC_ID_MASK) << HSC_ID_BITS) | \
+                (((port_id) & HSC_PORT_ID_MASK) << HSC_PORT_ID_BITS))
+
+enum {
+        HSC_CH_OPEN,
+        HSC_CH_READ,
+        HSC_CH_WRITE,
+        HSC_CH_WLINE,
+};
+
+enum {
+        HSC_RX,
+        HSC_TX,
+};
+
+struct hsc_client_data;
+/**
+ * struct hsc_channel - hsi_char internal channel data
+ * @ch: channel number
+ * @flags: Keeps state of the channel (open/close, reading, writing)
+ * @free_msgs_list: List of free HSI messages/requests
+ * @rx_msgs_queue: List of pending RX requests
+ * @tx_msgs_queue: List of pending TX requests
+ * @lock: Serialize access to the lists
+ * @cl: reference to the associated hsi_client
+ * @cl_data: reference to the client data that this channels belongs to
+ * @rx_wait: RX requests wait queue
+ * @tx_wait: TX requests wait queue
+ */
+struct hsc_channel {
+        unsigned int            ch;
+        unsigned long           flags;
+        struct list_head        free_msgs_list;
+        struct list_head        rx_msgs_queue;
+        struct list_head        tx_msgs_queue;
+        spinlock_t              lock;
+        struct hsi_client       *cl;
+        struct hsc_client_data *cl_data;
+        wait_queue_head_t       rx_wait;
+        wait_queue_head_t       tx_wait;
+};
+
+/**
+ * struct hsc_client_data - hsi_char internal client data
+ * @cdev: Characther device associated to the hsi_client
+ * @lock: Lock to serialize open/close access
+ * @flags: Keeps track of port state (rx hwbreak armed)
+ * @usecnt: Use count for claiming the HSI port (mutex protected)
+ * @cl: Referece to the HSI client
+ * @channels: Array of channels accessible by the client
+ */
+struct hsc_client_data {
+        struct cdev             cdev;
+        struct mutex            lock;
+        unsigned long           flags;
+        unsigned int            usecnt;
+        struct hsi_client       *cl;
+        struct hsc_channel      channels[HSC_DEVS];
+};
+
+/* Stores the major number dynamically allocated for hsi_char */
+static unsigned int hsc_major;
+/* Maximum buffer size that hsi_char will accept from userspace */
+static unsigned int max_data_size = 0x1000;
+module_param(max_data_size, uint, S_IRUSR | S_IWUSR);
+MODULE_PARM_DESC(max_data_size, "max read/write data size [4,8..65536] (^2)");
+
+static void hsc_add_tail(struct hsc_channel *channel, struct hsi_msg *msg,
+                                                        struct list_head *queue)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&channel->lock, flags);
+        list_add_tail(&msg->link, queue);
+        spin_unlock_irqrestore(&channel->lock, flags);
+}
+
+static struct hsi_msg *hsc_get_first_msg(struct hsc_channel *channel,
+                                                        struct list_head *queue)
+{
+        struct hsi_msg *msg = NULL;
+        unsigned long flags;
+
+        spin_lock_irqsave(&channel->lock, flags);
+
+        if (list_empty(queue))
+                goto out;
+
+        msg = list_first_entry(queue, struct hsi_msg, link);
+        list_del(&msg->link);
+out:
+        spin_unlock_irqrestore(&channel->lock, flags);
+
+        return msg;
+}
+
+static inline void hsc_msg_free(struct hsi_msg *msg)
+{
+        kfree(sg_virt(msg->sgt.sgl));
+        hsi_free_msg(msg);
+}
+
+static void hsc_free_list(struct list_head *list)
+{
+        struct hsi_msg *msg, *tmp;
+
+        list_for_each_entry_safe(msg, tmp, list, link) {
+                list_del(&msg->link);
+                hsc_msg_free(msg);
+        }
+}
+
+static void hsc_reset_list(struct hsc_channel *channel, struct list_head *l)
+{
+        unsigned long flags;
+        LIST_HEAD(list);
+
+        spin_lock_irqsave(&channel->lock, flags);
+        list_splice_init(l, &list);
+        spin_unlock_irqrestore(&channel->lock, flags);
+
+        hsc_free_list(&list);
+}
+
+static inline struct hsi_msg *hsc_msg_alloc(unsigned int alloc_size)
+{
+        struct hsi_msg *msg;
+        void *buf;
+
+        msg = hsi_alloc_msg(1, GFP_KERNEL);
+        if (!msg)
+                goto out;
+        buf = kmalloc(alloc_size, GFP_KERNEL);
+        if (!buf) {
+                hsi_free_msg(msg);
+                goto out;
+        }
+        sg_init_one(msg->sgt.sgl, buf, alloc_size);
+        /* Ignore false positive, due to sg pointer handling */
+        kmemleak_ignore(buf);
+
+        return msg;
+out:
+        return NULL;
+}
+
+static inline int hsc_msgs_alloc(struct hsc_channel *channel)
+{
+        struct hsi_msg *msg;
+        int i;
+
+        for (i = 0; i < HSC_MSGS; i++) {
+                msg = hsc_msg_alloc(max_data_size);
+                if (!msg)
+                        goto out;
+                msg->channel = channel->ch;
+                list_add_tail(&msg->link, &channel->free_msgs_list);
+        }
+
+        return 0;
+out:
+        hsc_free_list(&channel->free_msgs_list);
+
+        return -ENOMEM;
+}
+
+static inline unsigned int hsc_msg_len_get(struct hsi_msg *msg)
+{
+        return msg->sgt.sgl->length;
+}
+
+static inline void hsc_msg_len_set(struct hsi_msg *msg, unsigned int len)
+{
+        msg->sgt.sgl->length = len;
+}
+
+static void hsc_rx_completed(struct hsi_msg *msg)
+{
+        struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+        struct hsc_channel *channel = cl_data->channels + msg->channel;
+
+        if (test_bit(HSC_CH_READ, &channel->flags)) {
+                hsc_add_tail(channel, msg, &channel->rx_msgs_queue);
+                wake_up(&channel->rx_wait);
+        } else {
+                hsc_add_tail(channel, msg, &channel->free_msgs_list);
+        }
+}
+
+static void hsc_rx_msg_destructor(struct hsi_msg *msg)
+{
+        msg->status = HSI_STATUS_ERROR;
+        hsc_msg_len_set(msg, 0);
+        hsc_rx_completed(msg);
+}
+
+static void hsc_tx_completed(struct hsi_msg *msg)
+{
+        struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+        struct hsc_channel *channel = cl_data->channels + msg->channel;
+
+        if (test_bit(HSC_CH_WRITE, &channel->flags)) {
+                hsc_add_tail(channel, msg, &channel->tx_msgs_queue);
+                wake_up(&channel->tx_wait);
+        } else {
+                hsc_add_tail(channel, msg, &channel->free_msgs_list);
+        }
+}
+
+static void hsc_tx_msg_destructor(struct hsi_msg *msg)
+{
+        msg->status = HSI_STATUS_ERROR;
+        hsc_msg_len_set(msg, 0);
+        hsc_tx_completed(msg);
+}
+
+static void hsc_break_req_destructor(struct hsi_msg *msg)
+{
+        struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+
+        hsi_free_msg(msg);
+        clear_bit(HSC_RXBREAK, &cl_data->flags);
+}
+
+static void hsc_break_received(struct hsi_msg *msg)
+{
+        struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+        struct hsc_channel *channel = cl_data->channels;
+        int i, ret;
+
+        /* Broadcast HWBREAK on all channels */
+        for (i = 0; i < HSC_DEVS; i++, channel++) {
+                struct hsi_msg *msg2;
+
+                if (!test_bit(HSC_CH_READ, &channel->flags))
+                        continue;
+                msg2 = hsc_get_first_msg(channel, &channel->free_msgs_list);
+                if (!msg2)
+                        continue;
+                clear_bit(HSC_CH_READ, &channel->flags);
+                hsc_msg_len_set(msg2, 0);
+                msg2->status = HSI_STATUS_COMPLETED;
+                hsc_add_tail(channel, msg2, &channel->rx_msgs_queue);
+                wake_up(&channel->rx_wait);
+        }
+        hsi_flush(msg->cl);
+        ret = hsi_async_read(msg->cl, msg);
+        if (ret < 0)
+                hsc_break_req_destructor(msg);
+}
+
+static int hsc_break_request(struct hsi_client *cl)
+{
+        struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
+        struct hsi_msg *msg;
+        int ret;
+
+        if (test_and_set_bit(HSC_RXBREAK, &cl_data->flags))
+                return -EBUSY;
+
+        msg = hsi_alloc_msg(0, GFP_KERNEL);
+        if (!msg) {
+                clear_bit(HSC_RXBREAK, &cl_data->flags);
+                return -ENOMEM;
+        }
+        msg->break_frame = 1;
+        msg->complete = hsc_break_received;
+        msg->destructor = hsc_break_req_destructor;
+        ret = hsi_async_read(cl, msg);
+        if (ret < 0)
+                hsc_break_req_destructor(msg);
+
+        return ret;
+}
+
+static int hsc_break_send(struct hsi_client *cl)
+{
+        struct hsi_msg *msg;
+        int ret;
+
+        msg = hsi_alloc_msg(0, GFP_ATOMIC);
+        if (!msg)
+                return -ENOMEM;
+        msg->break_frame = 1;
+        msg->complete = hsi_free_msg;
+        msg->destructor = hsi_free_msg;
+        ret = hsi_async_write(cl, msg);
+        if (ret < 0)
+                hsi_free_msg(msg);
+
+        return ret;
+}
+
+static int hsc_rx_set(struct hsi_client *cl, struct hsc_rx_config *rxc)
+{
+        struct hsi_config tmp;
+        int ret;
+
+        if ((rxc->mode != HSI_MODE_STREAM) && (rxc->mode != HSI_MODE_FRAME))
+                return -EINVAL;
+        if ((rxc->channels == 0) || (rxc->channels > HSC_DEVS))
+                return -EINVAL;
+        if (rxc->channels & (rxc->channels - 1))
+                return -EINVAL;
+        if ((rxc->flow != HSI_FLOW_SYNC) && (rxc->flow != HSI_FLOW_PIPE))
+                return -EINVAL;
+        tmp = cl->rx_cfg;
+        cl->rx_cfg.mode = rxc->mode;
+        cl->rx_cfg.channels = rxc->channels;
+        cl->rx_cfg.flow = rxc->flow;
+        ret = hsi_setup(cl);
+        if (ret < 0) {
+                cl->rx_cfg = tmp;
+                return ret;
+        }
+        if (rxc->mode == HSI_MODE_FRAME)
+                hsc_break_request(cl);
+
+        return ret;
+}
+
+static inline void hsc_rx_get(struct hsi_client *cl, struct hsc_rx_config *rxc)
+{
+        rxc->mode = cl->rx_cfg.mode;
+        rxc->channels = cl->rx_cfg.channels;
+        rxc->flow = cl->rx_cfg.flow;
+}
+
+static int hsc_tx_set(struct hsi_client *cl, struct hsc_tx_config *txc)
+{
+        struct hsi_config tmp;
+        int ret;
+
+        if ((txc->mode != HSI_MODE_STREAM) && (txc->mode != HSI_MODE_FRAME))
+                return -EINVAL;
+        if ((txc->channels == 0) || (txc->channels > HSC_DEVS))
+                return -EINVAL;
+        if (txc->channels & (txc->channels - 1))
+                return -EINVAL;
+        if ((txc->arb_mode != HSI_ARB_RR) && (txc->arb_mode != HSI_ARB_PRIO))
+                return -EINVAL;
+        tmp = cl->tx_cfg;
+        cl->tx_cfg.mode = txc->mode;
+        cl->tx_cfg.channels = txc->channels;
+        cl->tx_cfg.speed = txc->speed;
+        cl->tx_cfg.arb_mode = txc->arb_mode;
+        ret = hsi_setup(cl);
+        if (ret < 0) {
+                cl->tx_cfg = tmp;
+                return ret;
+        }
+
+        return ret;
+}
+
+static inline void hsc_tx_get(struct hsi_client *cl, struct hsc_tx_config *txc)
+{
+        txc->mode = cl->tx_cfg.mode;
+        txc->channels = cl->tx_cfg.channels;
+        txc->speed = cl->tx_cfg.speed;
+        txc->arb_mode = cl->tx_cfg.arb_mode;
+}
+
+static ssize_t hsc_read(struct file *file, char __user *buf, size_t len,
+                                                loff_t *ppos __maybe_unused)
+{
+        struct hsc_channel *channel = file->private_data;
+        struct hsi_msg *msg;
+        ssize_t ret;
+
+        if (len == 0)
+                return 0;
+        if (!IS_ALIGNED(len, sizeof(u32)))
+                return -EINVAL;
+        if (len > max_data_size)
+                len = max_data_size;
+        if (channel->ch >= channel->cl->rx_cfg.channels)
+                return -ECHRNG;
+        if (test_and_set_bit(HSC_CH_READ, &channel->flags))
+                return -EBUSY;
+        msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
+        if (!msg) {
+                ret = -ENOSPC;
+                goto out;
+        }
+        hsc_msg_len_set(msg, len);
+        msg->complete = hsc_rx_completed;
+        msg->destructor = hsc_rx_msg_destructor;
+        ret = hsi_async_read(channel->cl, msg);
+        if (ret < 0) {
+                hsc_add_tail(channel, msg, &channel->free_msgs_list);
+                goto out;
+        }
+
+        ret = wait_event_interruptible(channel->rx_wait,
+                                        !list_empty(&channel->rx_msgs_queue));
+        if (ret < 0) {
+                clear_bit(HSC_CH_READ, &channel->flags);
+                hsi_flush(channel->cl);
+                return -EINTR;
+        }
+
+        msg = hsc_get_first_msg(channel, &channel->rx_msgs_queue);
+        if (msg) {
+                if (msg->status != HSI_STATUS_ERROR) {
+                        ret = copy_to_user((void __user *)buf,
+                        sg_virt(msg->sgt.sgl), hsc_msg_len_get(msg));
+                        if (ret)
+                                ret = -EFAULT;
+                        else
+                                ret = hsc_msg_len_get(msg);
+                } else {
+                        ret = -EIO;
+                }
+                hsc_add_tail(channel, msg, &channel->free_msgs_list);
+        }
+out:
+        clear_bit(HSC_CH_READ, &channel->flags);
+
+        return ret;
+}
+
+static ssize_t hsc_write(struct file *file, const char __user *buf, size_t len,
+                                                loff_t *ppos __maybe_unused)
+{
+        struct hsc_channel *channel = file->private_data;
+        struct hsi_msg *msg;
+        ssize_t ret;
+
+        if ((len == 0) || !IS_ALIGNED(len, sizeof(u32)))
+                return -EINVAL;
+        if (len > max_data_size)
+                len = max_data_size;
+        if (channel->ch >= channel->cl->tx_cfg.channels)
+                return -ECHRNG;
+        if (test_and_set_bit(HSC_CH_WRITE, &channel->flags))
+                return -EBUSY;
+        msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
+        if (!msg) {
+                clear_bit(HSC_CH_WRITE, &channel->flags);
+                return -ENOSPC;
+        }
+        if (copy_from_user(sg_virt(msg->sgt.sgl), (void __user *)buf, len)) {
+                ret = -EFAULT;
+                goto out;
+        }
+        hsc_msg_len_set(msg, len);
+        msg->complete = hsc_tx_completed;
+        msg->destructor = hsc_tx_msg_destructor;
+        ret = hsi_async_write(channel->cl, msg);
+        if (ret < 0)
+                goto out;
+
+        ret = wait_event_interruptible(channel->tx_wait,
+                                        !list_empty(&channel->tx_msgs_queue));
+        if (ret < 0) {
+                clear_bit(HSC_CH_WRITE, &channel->flags);
+                hsi_flush(channel->cl);
+                return -EINTR;
+        }
+
+        msg = hsc_get_first_msg(channel, &channel->tx_msgs_queue);
+        if (msg) {
+                if (msg->status == HSI_STATUS_ERROR)
+                        ret = -EIO;
+                else
+                        ret = hsc_msg_len_get(msg);
+
+                hsc_add_tail(channel, msg, &channel->free_msgs_list);
+        }
+out:
+        clear_bit(HSC_CH_WRITE, &channel->flags);
+
+        return ret;
+}
+
+static long hsc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        struct hsc_channel *channel = file->private_data;
+        unsigned int state;
+        struct hsc_rx_config rxc;
+        struct hsc_tx_config txc;
+        long ret = 0;
+
+        switch (cmd) {
+        case HSC_RESET:
+                hsi_flush(channel->cl);
+                break;
+        case HSC_SET_PM:
+                if (copy_from_user(&state, (void __user *)arg, sizeof(state)))
+                        return -EFAULT;
+                if (state == HSC_PM_DISABLE) {
+                        if (test_and_set_bit(HSC_CH_WLINE, &channel->flags))
+                                return -EINVAL;
+                        ret = hsi_start_tx(channel->cl);
+                } else if (state == HSC_PM_ENABLE) {
+                        if (!test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
+                                return -EINVAL;
+                        ret = hsi_stop_tx(channel->cl);
+                } else {
+                        ret = -EINVAL;
+                }
+                break;
+        case HSC_SEND_BREAK:
+                return hsc_break_send(channel->cl);
+        case HSC_SET_RX:
+                if (copy_from_user(&rxc, (void __user *)arg, sizeof(rxc)))
+                        return -EFAULT;
+                return hsc_rx_set(channel->cl, &rxc);
+        case HSC_GET_RX:
+                hsc_rx_get(channel->cl, &rxc);
+                if (copy_to_user((void __user *)arg, &rxc, sizeof(rxc)))
+                        return -EFAULT;
+                break;
+        case HSC_SET_TX:
+                if (copy_from_user(&txc, (void __user *)arg, sizeof(txc)))
+                        return -EFAULT;
+                return hsc_tx_set(channel->cl, &txc);
+        case HSC_GET_TX:
+                hsc_tx_get(channel->cl, &txc);
+                if (copy_to_user((void __user *)arg, &txc, sizeof(txc)))
+                        return -EFAULT;
+                break;
+        default:
+                return -ENOIOCTLCMD;
+        }
+
+        return ret;
+}
+
+static inline void __hsc_port_release(struct hsc_client_data *cl_data)
+{
+        BUG_ON(cl_data->usecnt == 0);
+
+        if (--cl_data->usecnt == 0) {
+                hsi_flush(cl_data->cl);
+                hsi_release_port(cl_data->cl);
+        }
+}
+
+static int hsc_open(struct inode *inode, struct file *file)
+{
+        struct hsc_client_data *cl_data;
+        struct hsc_channel *channel;
+        int ret = 0;
+
+        pr_debug("open, minor = %d\n", iminor(inode));
+
+        cl_data = container_of(inode->i_cdev, struct hsc_client_data, cdev);
+        mutex_lock(&cl_data->lock);
+        channel = cl_data->channels + (iminor(inode) & HSC_CH_MASK);
+
+        if (test_and_set_bit(HSC_CH_OPEN, &channel->flags)) {
+                ret = -EBUSY;
+                goto out;
+        }
+        /*
+         * Check if we have already claimed the port associated to the HSI
+         * client. If not then try to claim it, else increase its refcount
+         */
+        if (cl_data->usecnt == 0) {
+                ret = hsi_claim_port(cl_data->cl, 0);
+                if (ret < 0)
+                        goto out;
+                hsi_setup(cl_data->cl);
+        }
+        cl_data->usecnt++;
+
+        ret = hsc_msgs_alloc(channel);
+        if (ret < 0) {
+                __hsc_port_release(cl_data);
+                goto out;
+        }
+
+        file->private_data = channel;
+        mutex_unlock(&cl_data->lock);
+
+        return ret;
+out:
+        mutex_unlock(&cl_data->lock);
+
+        return ret;
+}
+
+static int hsc_release(struct inode *inode __maybe_unused, struct file *file)
+{
+        struct hsc_channel *channel = file->private_data;
+        struct hsc_client_data *cl_data = channel->cl_data;
+
+        mutex_lock(&cl_data->lock);
+        file->private_data = NULL;
+        if (test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
+                hsi_stop_tx(channel->cl);
+        __hsc_port_release(cl_data);
+        hsc_reset_list(channel, &channel->rx_msgs_queue);
+        hsc_reset_list(channel, &channel->tx_msgs_queue);
+        hsc_reset_list(channel, &channel->free_msgs_list);
+        clear_bit(HSC_CH_READ, &channel->flags);
+        clear_bit(HSC_CH_WRITE, &channel->flags);
+        clear_bit(HSC_CH_OPEN, &channel->flags);
+        wake_up(&channel->rx_wait);
+        wake_up(&channel->tx_wait);
+        mutex_unlock(&cl_data->lock);
+
+        return 0;
+}
+
+static const struct file_operations hsc_fops = {
+        .owner          = THIS_MODULE,
+        .read           = hsc_read,
+        .write          = hsc_write,
+        .unlocked_ioctl = hsc_ioctl,
+        .open           = hsc_open,
+        .release        = hsc_release,
+};
+
+static void __devinit hsc_channel_init(struct hsc_channel *channel)
+{
+        init_waitqueue_head(&channel->rx_wait);
+        init_waitqueue_head(&channel->tx_wait);
+        spin_lock_init(&channel->lock);
+        INIT_LIST_HEAD(&channel->free_msgs_list);
+        INIT_LIST_HEAD(&channel->rx_msgs_queue);
+        INIT_LIST_HEAD(&channel->tx_msgs_queue);
+}
+
+static int __devinit hsc_probe(struct device *dev)
+{
+        const char devname[] = "hsi_char";
+        struct hsc_client_data *cl_data;
+        struct hsc_channel *channel;
+        struct hsi_client *cl = to_hsi_client(dev);
+        unsigned int hsc_baseminor;
+        dev_t hsc_dev;
+        int ret;
+        int i;
+
+        cl_data = kzalloc(sizeof(*cl_data), GFP_KERNEL);
+        if (!cl_data) {
+                dev_err(dev, "Could not allocate hsc_client_data\n");
+                return -ENOMEM;
+        }
+        hsc_baseminor = HSC_BASEMINOR(hsi_id(cl), hsi_port_id(cl));
+        if (!hsc_major) {
+                ret = alloc_chrdev_region(&hsc_dev, hsc_baseminor,
+                                                HSC_DEVS, devname);
+                if (ret > 0)
+                        hsc_major = MAJOR(hsc_dev);
+        } else {
+                hsc_dev = MKDEV(hsc_major, hsc_baseminor);
+                ret = register_chrdev_region(hsc_dev, HSC_DEVS, devname);
+        }
+        if (ret < 0) {
+                dev_err(dev, "Device %s allocation failed %d\n",
+                                        hsc_major ? "minor" : "major", ret);
+                goto out1;
+        }
+        mutex_init(&cl_data->lock);
+        hsi_client_set_drvdata(cl, cl_data);
+        cdev_init(&cl_data->cdev, &hsc_fops);
+        cl_data->cdev.owner = THIS_MODULE;
+        cl_data->cl = cl;
+        for (i = 0, channel = cl_data->channels; i < HSC_DEVS; i++, channel++) {
+                hsc_channel_init(channel);
+                channel->ch = i;
+                channel->cl = cl;
+                channel->cl_data = cl_data;
+        }
+
+        /* 1 hsi client -> N char devices (one for each channel) */
+        ret = cdev_add(&cl_data->cdev, hsc_dev, HSC_DEVS);
+        if (ret) {
+                dev_err(dev, "Could not add char device %d\n", ret);
+                goto out2;
+        }
+
+        return 0;
+out2:
+        unregister_chrdev_region(hsc_dev, HSC_DEVS);
+out1:
+        kfree(cl_data);
+
+        return ret;
+}
+
+static int __devexit hsc_remove(struct device *dev)
+{
+        struct hsi_client *cl = to_hsi_client(dev);
+        struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
+        dev_t hsc_dev = cl_data->cdev.dev;
+
+        cdev_del(&cl_data->cdev);
+        unregister_chrdev_region(hsc_dev, HSC_DEVS);
+        hsi_client_set_drvdata(cl, NULL);
+        kfree(cl_data);
+
+        return 0;
+}
+
+static struct hsi_client_driver hsc_driver = {
+        .driver = {
+                .name   = "hsi_char",
+                .owner  = THIS_MODULE,
+                .probe  = hsc_probe,
+                .remove = __devexit_p(hsc_remove),
+        },
+};
+
+static int __init hsc_init(void)
+{
+        int ret;
+
+        if ((max_data_size < 4) || (max_data_size > 0x10000) ||
+                (max_data_size & (max_data_size - 1))) {
+                pr_err("Invalid max read/write data size");
+                return -EINVAL;
+        }
+
+        ret = hsi_register_client_driver(&hsc_driver);
+        if (ret) {
+                pr_err("Error while registering HSI/SSI driver %d", ret);
+                return ret;
+        }
+
+        pr_info("HSI/SSI char device loaded\n");
+
+        return 0;
+}
+module_init(hsc_init);
+
+static void __exit hsc_exit(void)
+{
+        hsi_unregister_client_driver(&hsc_driver);
+        pr_info("HSI char device removed\n");
+}
+module_exit(hsc_exit);
+
+MODULE_AUTHOR("Andras Domokos <andras.domokos@nokia.com>");
+MODULE_ALIAS("hsi:hsi_char");
+MODULE_DESCRIPTION("HSI character device");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/hsi.c b/drivers/hsi/hsi.c
new file mode 100644
index 00000000000..4e2d79b7933
--- /dev/null
+++ b/drivers/hsi/hsi.c
@@ -0,0 +1,494 @@
+/*
+ * HSI core.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+#include <linux/hsi/hsi.h>
+#include <linux/compiler.h>
+#include <linux/rwsem.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include "hsi_core.h"
+
+static struct device_type hsi_ctrl = {
+        .name   = "hsi_controller",
+};
+
+static struct device_type hsi_cl = {
+        .name   = "hsi_client",
+};
+
+static struct device_type hsi_port = {
+        .name   = "hsi_port",
+};
+
+static ssize_t modalias_show(struct device *dev,
+                        struct device_attribute *a __maybe_unused, char *buf)
+{
+        return sprintf(buf, "hsi:%s\n", dev_name(dev));
+}
+
+static struct device_attribute hsi_bus_dev_attrs[] = {
+        __ATTR_RO(modalias),
+        __ATTR_NULL,
+};
+
+static int hsi_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+        if (dev->type == &hsi_cl)
+                add_uevent_var(env, "MODALIAS=hsi:%s", dev_name(dev));
+
+        return 0;
+}
+
+static int hsi_bus_match(struct device *dev, struct device_driver *driver)
+{
+        return strcmp(dev_name(dev), driver->name) == 0;
+}
+
+static struct bus_type hsi_bus_type = {
+        .name           = "hsi",
+        .dev_attrs      = hsi_bus_dev_attrs,
+        .match          = hsi_bus_match,
+        .uevent         = hsi_bus_uevent,
+};
+
+static void hsi_client_release(struct device *dev)
+{
+        kfree(to_hsi_client(dev));
+}
+
+static void hsi_new_client(struct hsi_port *port, struct hsi_board_info *info)
+{
+        struct hsi_client *cl;
+        unsigned long flags;
+
+        cl = kzalloc(sizeof(*cl), GFP_KERNEL);
+        if (!cl)
+                return;
+        cl->device.type = &hsi_cl;
+        cl->tx_cfg = info->tx_cfg;
+        cl->rx_cfg = info->rx_cfg;
+        cl->device.bus = &hsi_bus_type;
+        cl->device.parent = &port->device;
+        cl->device.release = hsi_client_release;
+        dev_set_name(&cl->device, info->name);
+        cl->device.platform_data = info->platform_data;
+        spin_lock_irqsave(&port->clock, flags);
+        list_add_tail(&cl->link, &port->clients);
+        spin_unlock_irqrestore(&port->clock, flags);
+        if (info->archdata)
+                cl->device.archdata = *info->archdata;
+        if (device_register(&cl->device) < 0) {
+                pr_err("hsi: failed to register client: %s\n", info->name);
+                kfree(cl);
+        }
+}
+
+static void hsi_scan_board_info(struct hsi_controller *hsi)
+{
+        struct hsi_cl_info *cl_info;
+        struct hsi_port *p;
+
+        list_for_each_entry(cl_info, &hsi_board_list, list)
+                if (cl_info->info.hsi_id == hsi->id) {
+                        p = hsi_find_port_num(hsi, cl_info->info.port);
+                        if (!p)
+                                continue;
+                        hsi_new_client(p, &cl_info->info);
+                }
+}
+
+static int hsi_remove_client(struct device *dev, void *data __maybe_unused)
+{
+        struct hsi_client *cl = to_hsi_client(dev);
+        struct hsi_port *port = to_hsi_port(dev->parent);
+        unsigned long flags;
+
+        spin_lock_irqsave(&port->clock, flags);
+        list_del(&cl->link);
+        spin_unlock_irqrestore(&port->clock, flags);
+        device_unregister(dev);
+
+        return 0;
+}
+
+static int hsi_remove_port(struct device *dev, void *data __maybe_unused)
+{
+        device_for_each_child(dev, NULL, hsi_remove_client);
+        device_unregister(dev);
+
+        return 0;
+}
+
+static void hsi_controller_release(struct device *dev __maybe_unused)
+{
+}
+
+static void hsi_port_release(struct device *dev __maybe_unused)
+{
+}
+
+/**
+ * hsi_unregister_controller - Unregister an HSI controller
+ * @hsi: The HSI controller to register
+ */
+void hsi_unregister_controller(struct hsi_controller *hsi)
+{
+        device_for_each_child(&hsi->device, NULL, hsi_remove_port);
+        device_unregister(&hsi->device);
+}
+EXPORT_SYMBOL_GPL(hsi_unregister_controller);
+
+/**
+ * hsi_register_controller - Register an HSI controller and its ports
+ * @hsi: The HSI controller to register
+ *
+ * Returns -errno on failure, 0 on success.
+ */
+int hsi_register_controller(struct hsi_controller *hsi)
+{
+        unsigned int i;
+        int err;
+
+        hsi->device.type = &hsi_ctrl;
+        hsi->device.bus = &hsi_bus_type;
+        hsi->device.release = hsi_controller_release;
+        err = device_register(&hsi->device);
+        if (err < 0)
+                return err;
+        for (i = 0; i < hsi->num_ports; i++) {
+                hsi->port[i].device.parent = &hsi->device;
+                hsi->port[i].device.bus = &hsi_bus_type;
+                hsi->port[i].device.release = hsi_port_release;
+                hsi->port[i].device.type = &hsi_port;
+                INIT_LIST_HEAD(&hsi->port[i].clients);
+                spin_lock_init(&hsi->port[i].clock);
+                err = device_register(&hsi->port[i].device);
+                if (err < 0)
+                        goto out;
+        }
+        /* Populate HSI bus with HSI clients */
+        hsi_scan_board_info(hsi);
+
+        return 0;
+out:
+        hsi_unregister_controller(hsi);
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(hsi_register_controller);
+
+/**
+ * hsi_register_client_driver - Register an HSI client to the HSI bus
+ * @drv: HSI client driver to register
+ *
+ * Returns -errno on failure, 0 on success.
+ */
+int hsi_register_client_driver(struct hsi_client_driver *drv)
+{
+        drv->driver.bus = &hsi_bus_type;
+
+        return driver_register(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(hsi_register_client_driver);
+
+static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
+{
+        return 0;
+}
+
+static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
+{
+        return 0;
+}
+
+/**
+ * hsi_alloc_controller - Allocate an HSI controller and its ports
+ * @n_ports: Number of ports on the HSI controller
+ * @flags: Kernel allocation flags
+ *
+ * Return NULL on failure or a pointer to an hsi_controller on success.
+ */
+struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
+{
+        struct hsi_controller   *hsi;
+        struct hsi_port         *port;
+        unsigned int            i;
+
+        if (!n_ports)
+                return NULL;
+
+        port = kzalloc(sizeof(*port)*n_ports, flags);
+        if (!port)
+                return NULL;
+        hsi = kzalloc(sizeof(*hsi), flags);
+        if (!hsi)
+                goto out;
+        for (i = 0; i < n_ports; i++) {
+                dev_set_name(&port[i].device, "port%d", i);
+                port[i].num = i;
+                port[i].async = hsi_dummy_msg;
+                port[i].setup = hsi_dummy_cl;
+                port[i].flush = hsi_dummy_cl;
+                port[i].start_tx = hsi_dummy_cl;
+                port[i].stop_tx = hsi_dummy_cl;
+                port[i].release = hsi_dummy_cl;
+                mutex_init(&port[i].lock);
+        }
+        hsi->num_ports = n_ports;
+        hsi->port = port;
+
+        return hsi;
+out:
+        kfree(port);
+
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(hsi_alloc_controller);
+
+/**
+ * hsi_free_controller - Free an HSI controller
+ * @hsi: Pointer to HSI controller
+ */
+void hsi_free_controller(struct hsi_controller *hsi)
+{
+        if (!hsi)
+                return;
+
+        kfree(hsi->port);
+        kfree(hsi);
+}
+EXPORT_SYMBOL_GPL(hsi_free_controller);
+
+/**
+ * hsi_free_msg - Free an HSI message
+ * @msg: Pointer to the HSI message
+ *
+ * Client is responsible to free the buffers pointed by the scatterlists.
+ */
+void hsi_free_msg(struct hsi_msg *msg)
+{
+        if (!msg)
+                return;
+        sg_free_table(&msg->sgt);
+        kfree(msg);
+}
+EXPORT_SYMBOL_GPL(hsi_free_msg);
+
+/**
+ * hsi_alloc_msg - Allocate an HSI message
+ * @nents: Number of memory entries
+ * @flags: Kernel allocation flags
+ *
+ * nents can be 0. This mainly makes sense for read transfer.
+ * In that case, HSI drivers will call the complete callback when
+ * there is data to be read without consuming it.
+ *
+ * Return NULL on failure or a pointer to an hsi_msg on success.
+ */
+struct hsi_msg *hsi_alloc_msg(unsigned int nents, gfp_t flags)
+{
+        struct hsi_msg *msg;
+        int err;
+
+        msg = kzalloc(sizeof(*msg), flags);
+        if (!msg)
+                return NULL;
+
+        if (!nents)
+                return msg;
+
+        err = sg_alloc_table(&msg->sgt, nents, flags);
+        if (unlikely(err)) {
+                kfree(msg);
+                msg = NULL;
+        }
+
+        return msg;
+}
+EXPORT_SYMBOL_GPL(hsi_alloc_msg);
+
+/**
+ * hsi_async - Submit an HSI transfer to the controller
+ * @cl: HSI client sending the transfer
+ * @msg: The HSI transfer passed to controller
+ *
+ * The HSI message must have the channel, ttype, complete and destructor
+ * fields set beforehand. If nents > 0 then the client has to initialize
+ * also the scatterlists to point to the buffers to write to or read from.
+ *
+ * HSI controllers relay on pre-allocated buffers from their clients and they
+ * do not allocate buffers on their own.
+ *
+ * Once the HSI message transfer finishes, the HSI controller calls the
+ * complete callback with the status and actual_len fields of the HSI message
+ * updated. The complete callback can be called before returning from
+ * hsi_async.
+ *
+ * Returns -errno on failure or 0 on success
+ */
+int hsi_async(struct hsi_client *cl, struct hsi_msg *msg)
+{
+        struct hsi_port *port = hsi_get_port(cl);
+
+        if (!hsi_port_claimed(cl))
+                return -EACCES;
+
+        WARN_ON_ONCE(!msg->destructor || !msg->complete);
+        msg->cl = cl;
+
+        return port->async(msg);
+}
+EXPORT_SYMBOL_GPL(hsi_async);
+
+/**
+ * hsi_claim_port - Claim the HSI client's port
+ * @cl: HSI client that wants to claim its port
+ * @share: Flag to indicate if the client wants to share the port or not.
+ *
+ * Returns -errno on failure, 0 on success.
+ */
+int hsi_claim_port(struct hsi_client *cl, unsigned int share)
+{
+        struct hsi_port *port = hsi_get_port(cl);
+        int err = 0;
+
+        mutex_lock(&port->lock);
+        if ((port->claimed) && (!port->shared || !share)) {
+                err = -EBUSY;
+                goto out;
+        }
+        if (!try_module_get(to_hsi_controller(port->device.parent)->owner)) {
+                err = -ENODEV;
+                goto out;
+        }
+        port->claimed++;
+        port->shared = !!share;
+        cl->pclaimed = 1;
+out:
+        mutex_unlock(&port->lock);
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(hsi_claim_port);
+
+/**
+ * hsi_release_port - Release the HSI client's port
+ * @cl: HSI client which previously claimed its port
+ */
+void hsi_release_port(struct hsi_client *cl)
+{
+        struct hsi_port *port = hsi_get_port(cl);
+
+        mutex_lock(&port->lock);
+        /* Allow HW driver to do some cleanup */
+        port->release(cl);
+        if (cl->pclaimed)
+                port->claimed--;
+        BUG_ON(port->claimed < 0);
+        cl->pclaimed = 0;
+        if (!port->claimed)
+                port->shared = 0;
+        module_put(to_hsi_controller(port->device.parent)->owner);
+        mutex_unlock(&port->lock);
+}
+EXPORT_SYMBOL_GPL(hsi_release_port);
+
+static int hsi_start_rx(struct hsi_client *cl, void *data __maybe_unused)
+{
+        if (cl->hsi_start_rx)
+                (*cl->hsi_start_rx)(cl);
+
+        return 0;
+}
+
+static int hsi_stop_rx(struct hsi_client *cl, void *data __maybe_unused)
+{
+        if (cl->hsi_stop_rx)
+                (*cl->hsi_stop_rx)(cl);
+
+        return 0;
+}
+
+static int hsi_port_for_each_client(struct hsi_port *port, void *data,
+                                int (*fn)(struct hsi_client *cl, void *data))
+{
+        struct hsi_client *cl;
+
+        spin_lock(&port->clock);
+        list_for_each_entry(cl, &port->clients, link) {
+                spin_unlock(&port->clock);
+                (*fn)(cl, data);
+                spin_lock(&port->clock);
+        }
+        spin_unlock(&port->clock);
+
+        return 0;
+}
+
+/**
+ * hsi_event -Notifies clients about port events
+ * @port: Port where the event occurred
+ * @event: The event type
+ *
+ * Clients should not be concerned about wake line behavior. However, due
+ * to a race condition in HSI HW protocol, clients need to be notified
+ * about wake line changes, so they can implement a workaround for it.
+ *
+ * Events:
+ * HSI_EVENT_START_RX - Incoming wake line high
+ * HSI_EVENT_STOP_RX - Incoming wake line down
+ */
+void hsi_event(struct hsi_port *port, unsigned int event)
+{
+        int (*fn)(struct hsi_client *cl, void *data);
+
+        switch (event) {
+        case HSI_EVENT_START_RX:
+                fn = hsi_start_rx;
+                break;
+        case HSI_EVENT_STOP_RX:
+                fn = hsi_stop_rx;
+                break;
+        default:
+                return;
+        }
+        hsi_port_for_each_client(port, NULL, fn);
+}
+EXPORT_SYMBOL_GPL(hsi_event);
+
+static int __init hsi_init(void)
+{
+        return bus_register(&hsi_bus_type);
+}
+postcore_initcall(hsi_init);
+
+static void __exit hsi_exit(void)
+{
+        bus_unregister(&hsi_bus_type);
+}
+module_exit(hsi_exit);
+
+MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
+MODULE_DESCRIPTION("High-speed Synchronous Serial Interface (HSI) framework");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/hsi_boardinfo.c b/drivers/hsi/hsi_boardinfo.c
new file mode 100644
index 00000000000..e56bc6da5f9
--- /dev/null
+++ b/drivers/hsi/hsi_boardinfo.c
@@ -0,0 +1,62 @@
+/*
+ * HSI clients registration interface
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+#include <linux/hsi/hsi.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include "hsi_core.h"
+
+/*
+ * hsi_board_list is only used internally by the HSI framework.
+ * No one else is allowed to make use of it.
+ */
+LIST_HEAD(hsi_board_list);
+EXPORT_SYMBOL_GPL(hsi_board_list);
+
+/**
+ * hsi_register_board_info - Register HSI clients information
+ * @info: Array of HSI clients on the board
+ * @len: Length of the array
+ *
+ * HSI clients are statically declared and registered on board files.
+ *
+ * HSI clients will be automatically registered to the HSI bus once the
+ * controller and the port where the clients wishes to attach are registered
+ * to it.
+ *
+ * Return -errno on failure, 0 on success.
+ */
+int __init hsi_register_board_info(struct hsi_board_info const *info,
+                                                        unsigned int len)
+{
+        struct hsi_cl_info *cl_info;
+
+        cl_info = kzalloc(sizeof(*cl_info) * len, GFP_KERNEL);
+        if (!cl_info)
+                return -ENOMEM;
+
+        for (; len; len--, info++, cl_info++) {
+                cl_info->info = *info;
+                list_add_tail(&cl_info->list, &hsi_board_list);
+        }
+
+        return 0;
+}
diff --git a/drivers/hsi/hsi_core.h b/drivers/hsi/hsi_core.h
new file mode 100644
index 00000000000..ab5c2fb175f
--- /dev/null
+++ b/drivers/hsi/hsi_core.h
@@ -0,0 +1,35 @@
+/*
+ * HSI framework internal interfaces,
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef __LINUX_HSI_CORE_H__
+#define __LINUX_HSI_CORE_H__
+
+#include <linux/hsi/hsi.h>
+
+struct hsi_cl_info {
+        struct list_head        list;
+        struct hsi_board_info   info;
+};
+
+extern struct list_head hsi_board_list;
+
+#endif /* __LINUX_HSI_CORE_H__ */
diff --git a/include/linux/Kbuild b/include/linux/Kbuild
index d05df281035..3c9b616c834 100644
--- a/include/linux/Kbuild
+++ b/include/linux/Kbuild
@@ -3,6 +3,7 @@ header-y += can/
 header-y += caif/
 header-y += dvb/
 header-y += hdlc/
+header-y += hsi/
 header-y += isdn/
 header-y += mmc/
 header-y += nfsd/
diff --git a/include/linux/hsi/Kbuild b/include/linux/hsi/Kbuild
new file mode 100644
index 00000000000..271a770b478
--- /dev/null
+++ b/include/linux/hsi/Kbuild
@@ -0,0 +1 @@
+header-y += hsi_char.h
diff --git a/include/linux/hsi/hsi.h b/include/linux/hsi/hsi.h
new file mode 100644
index 00000000000..4b178067f40
--- /dev/null
+++ b/include/linux/hsi/hsi.h
@@ -0,0 +1,410 @@
+/*
+ * HSI core header file.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef __LINUX_HSI_H__
+#define __LINUX_HSI_H__
+
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/scatterlist.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <linux/module.h>
+
+/* HSI message ttype */
+#define HSI_MSG_READ    0
+#define HSI_MSG_WRITE   1
+
+/* HSI configuration values */
+enum {
+        HSI_MODE_STREAM = 1,
+        HSI_MODE_FRAME,
+};
+
+enum {
+        HSI_FLOW_SYNC,  /* Synchronized flow */
+        HSI_FLOW_PIPE,  /* Pipelined flow */
+};
+
+enum {
+        HSI_ARB_RR,     /* Round-robin arbitration */
+        HSI_ARB_PRIO,   /* Channel priority arbitration */
+};
+
+#define HSI_MAX_CHANNELS        16
+
+/* HSI message status codes */
+enum {
+        HSI_STATUS_COMPLETED,   /* Message transfer is completed */
+        HSI_STATUS_PENDING,     /* Message pending to be read/write (POLL) */
+        HSI_STATUS_PROCEEDING,  /* Message transfer is ongoing */
+        HSI_STATUS_QUEUED,      /* Message waiting to be served */
+        HSI_STATUS_ERROR,       /* Error when message transfer was ongoing */
+};
+
+/* HSI port event codes */
+enum {
+        HSI_EVENT_START_RX,
+        HSI_EVENT_STOP_RX,
+};
+
+/**
+ * struct hsi_config - Configuration for RX/TX HSI modules
+ * @mode: Bit transmission mode (STREAM or FRAME)
+ * @channels: Number of channels to use [1..16]
+ * @speed: Max bit transmission speed (Kbit/s)
+ * @flow: RX flow type (SYNCHRONIZED or PIPELINE)
+ * @arb_mode: Arbitration mode for TX frame (Round robin, priority)
+ */
+struct hsi_config {
+        unsigned int    mode;
+        unsigned int    channels;
+        unsigned int    speed;
+        union {
+                unsigned int    flow;           /* RX only */
+                unsigned int    arb_mode;       /* TX only */
+        };
+};
+
+/**
+ * struct hsi_board_info - HSI client board info
+ * @name: Name for the HSI device
+ * @hsi_id: HSI controller id where the client sits
+ * @port: Port number in the controller where the client sits
+ * @tx_cfg: HSI TX configuration
+ * @rx_cfg: HSI RX configuration
+ * @platform_data: Platform related data
+ * @archdata: Architecture-dependent device data
+ */
+struct hsi_board_info {
+        const char              *name;
+        unsigned int            hsi_id;
+        unsigned int            port;
+        struct hsi_config       tx_cfg;
+        struct hsi_config       rx_cfg;
+        void                    *platform_data;
+        struct dev_archdata     *archdata;
+};
+
+#ifdef CONFIG_HSI_BOARDINFO
+extern int hsi_register_board_info(struct hsi_board_info const *info,
+                                                        unsigned int len);
+#else
+static inline int hsi_register_board_info(struct hsi_board_info const *info,
+                                                        unsigned int len)
+{
+        return 0;
+}
+#endif /* CONFIG_HSI_BOARDINFO */
+
+/**
+ * struct hsi_client - HSI client attached to an HSI port
+ * @device: Driver model representation of the device
+ * @tx_cfg: HSI TX configuration
+ * @rx_cfg: HSI RX configuration
+ * @hsi_start_rx: Called after incoming wake line goes high
+ * @hsi_stop_rx: Called after incoming wake line goes low
+ */
+struct hsi_client {
+        struct device           device;
+        struct hsi_config       tx_cfg;
+        struct hsi_config       rx_cfg;
+        void                    (*hsi_start_rx)(struct hsi_client *cl);
+        void                    (*hsi_stop_rx)(struct hsi_client *cl);
+        /* private: */
+        unsigned int            pclaimed:1;
+        struct list_head        link;
+};
+
+#define to_hsi_client(dev) container_of(dev, struct hsi_client, device)
+
+static inline void hsi_client_set_drvdata(struct hsi_client *cl, void *data)
+{
+        dev_set_drvdata(&cl->device, data);
+}
+
+static inline void *hsi_client_drvdata(struct hsi_client *cl)
+{
+        return dev_get_drvdata(&cl->device);
+}
+
+/**
+ * struct hsi_client_driver - Driver associated to an HSI client
+ * @driver: Driver model representation of the driver
+ */
+struct hsi_client_driver {
+        struct device_driver    driver;
+};
+
+#define to_hsi_client_driver(drv) container_of(drv, struct hsi_client_driver,\
+                                                                        driver)
+
+int hsi_register_client_driver(struct hsi_client_driver *drv);
+
+static inline void hsi_unregister_client_driver(struct hsi_client_driver *drv)
+{
+        driver_unregister(&drv->driver);
+}
+
+/**
+ * struct hsi_msg - HSI message descriptor
+ * @link: Free to use by the current descriptor owner
+ * @cl: HSI device client that issues the transfer
+ * @sgt: Head of the scatterlist array
+ * @context: Client context data associated to the transfer
+ * @complete: Transfer completion callback
+ * @destructor: Destructor to free resources when flushing
+ * @status: Status of the transfer when completed
+ * @actual_len: Actual length of data transfered on completion
+ * @channel: Channel were to TX/RX the message
+ * @ttype: Transfer type (TX if set, RX otherwise)
+ * @break_frame: if true HSI will send/receive a break frame. Data buffers are
+ *              ignored in the request.
+ */
+struct hsi_msg {
+        struct list_head        link;
+        struct hsi_client       *cl;
+        struct sg_table         sgt;
+        void                    *context;
+
+        void                    (*complete)(struct hsi_msg *msg);
+        void                    (*destructor)(struct hsi_msg *msg);
+
+        int                     status;
+        unsigned int            actual_len;
+        unsigned int            channel;
+        unsigned int            ttype:1;
+        unsigned int            break_frame:1;
+};
+
+struct hsi_msg *hsi_alloc_msg(unsigned int n_frag, gfp_t flags);
+void hsi_free_msg(struct hsi_msg *msg);
+
+/**
+ * struct hsi_port - HSI port device
+ * @device: Driver model representation of the device
+ * @tx_cfg: Current TX path configuration
+ * @rx_cfg: Current RX path configuration
+ * @num: Port number
+ * @shared: Set when port can be shared by different clients
+ * @claimed: Reference count of clients which claimed the port
+ * @lock: Serialize port claim
+ * @async: Asynchronous transfer callback
+ * @setup: Callback to set the HSI client configuration
+ * @flush: Callback to clean the HW state and destroy all pending transfers
+ * @start_tx: Callback to inform that a client wants to TX data
+ * @stop_tx: Callback to inform that a client no longer wishes to TX data
+ * @release: Callback to inform that a client no longer uses the port
+ * @clients: List of hsi_clients using the port.
+ * @clock: Lock to serialize access to the clients list.
+ */
+struct hsi_port {
+        struct device                   device;
+        struct hsi_config               tx_cfg;
+        struct hsi_config               rx_cfg;
+        unsigned int                    num;
+        unsigned int                    shared:1;
+        int                             claimed;
+        struct mutex                    lock;
+        int                             (*async)(struct hsi_msg *msg);
+        int                             (*setup)(struct hsi_client *cl);
+        int                             (*flush)(struct hsi_client *cl);
+        int                             (*start_tx)(struct hsi_client *cl);
+        int                             (*stop_tx)(struct hsi_client *cl);
+        int                             (*release)(struct hsi_client *cl);
+        struct list_head                clients;
+        spinlock_t                      clock;
+};
+
+#define to_hsi_port(dev) container_of(dev, struct hsi_port, device)
+#define hsi_get_port(cl) to_hsi_port((cl)->device.parent)
+
+void hsi_event(struct hsi_port *port, unsigned int event);
+int hsi_claim_port(struct hsi_client *cl, unsigned int share);
+void hsi_release_port(struct hsi_client *cl);
+
+static inline int hsi_port_claimed(struct hsi_client *cl)
+{
+        return cl->pclaimed;
+}
+
+static inline void hsi_port_set_drvdata(struct hsi_port *port, void *data)
+{
+        dev_set_drvdata(&port->device, data);
+}
+
+static inline void *hsi_port_drvdata(struct hsi_port *port)
+{
+        return dev_get_drvdata(&port->device);
+}
+
+/**
+ * struct hsi_controller - HSI controller device
+ * @device: Driver model representation of the device
+ * @owner: Pointer to the module owning the controller
+ * @id: HSI controller ID
+ * @num_ports: Number of ports in the HSI controller
+ * @port: Array of HSI ports
+ */
+struct hsi_controller {
+        struct device           device;
+        struct module           *owner;
+        unsigned int            id;
+        unsigned int            num_ports;
+        struct hsi_port         *port;
+};
+
+#define to_hsi_controller(dev) container_of(dev, struct hsi_controller, device)
+
+struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags);
+void hsi_free_controller(struct hsi_controller *hsi);
+int hsi_register_controller(struct hsi_controller *hsi);
+void hsi_unregister_controller(struct hsi_controller *hsi);
+
+static inline void hsi_controller_set_drvdata(struct hsi_controller *hsi,
+                                                                void *data)
+{
+        dev_set_drvdata(&hsi->device, data);
+}
+
+static inline void *hsi_controller_drvdata(struct hsi_controller *hsi)
+{
+        return dev_get_drvdata(&hsi->device);
+}
+
+static inline struct hsi_port *hsi_find_port_num(struct hsi_controller *hsi,
+                                                        unsigned int num)
+{
+        return (num < hsi->num_ports) ? &hsi->port[num] : NULL;
+}
+
+/*
+ * API for HSI clients
+ */
+int hsi_async(struct hsi_client *cl, struct hsi_msg *msg);
+
+/**
+ * hsi_id - Get HSI controller ID associated to a client
+ * @cl: Pointer to a HSI client
+ *
+ * Return the controller id where the client is attached to
+ */
+static inline unsigned int hsi_id(struct hsi_client *cl)
+{
+        return  to_hsi_controller(cl->device.parent->parent)->id;
+}
+
+/**
+ * hsi_port_id - Gets the port number a client is attached to
+ * @cl: Pointer to HSI client
+ *
+ * Return the port number associated to the client
+ */
+static inline unsigned int hsi_port_id(struct hsi_client *cl)
+{
+        return  to_hsi_port(cl->device.parent)->num;
+}
+
+/**
+ * hsi_setup - Configure the client's port
+ * @cl: Pointer to the HSI client
+ *
+ * When sharing ports, clients should either relay on a single
+ * client setup or have the same setup for all of them.
+ *
+ * Return -errno on failure, 0 on success
+ */
+static inline int hsi_setup(struct hsi_client *cl)
+{
+        if (!hsi_port_claimed(cl))
+                return -EACCES;
+        return  hsi_get_port(cl)->setup(cl);
+}
+
+/**
+ * hsi_flush - Flush all pending transactions on the client's port
+ * @cl: Pointer to the HSI client
+ *
+ * This function will destroy all pending hsi_msg in the port and reset
+ * the HW port so it is ready to receive and transmit from a clean state.
+ *
+ * Return -errno on failure, 0 on success
+ */
+static inline int hsi_flush(struct hsi_client *cl)
+{
+        if (!hsi_port_claimed(cl))
+                return -EACCES;
+        return hsi_get_port(cl)->flush(cl);
+}
+
+/**
+ * hsi_async_read - Submit a read transfer
+ * @cl: Pointer to the HSI client
+ * @msg: HSI message descriptor of the transfer
+ *
+ * Return -errno on failure, 0 on success
+ */
+static inline int hsi_async_read(struct hsi_client *cl, struct hsi_msg *msg)
+{
+        msg->ttype = HSI_MSG_READ;
+        return hsi_async(cl, msg);
+}
+
+/**
+ * hsi_async_write - Submit a write transfer
+ * @cl: Pointer to the HSI client
+ * @msg: HSI message descriptor of the transfer
+ *
+ * Return -errno on failure, 0 on success
+ */
+static inline int hsi_async_write(struct hsi_client *cl, struct hsi_msg *msg)
+{
+        msg->ttype = HSI_MSG_WRITE;
+        return hsi_async(cl, msg);
+}
+
+/**
+ * hsi_start_tx - Signal the port that the client wants to start a TX
+ * @cl: Pointer to the HSI client
+ *
+ * Return -errno on failure, 0 on success
+ */
+static inline int hsi_start_tx(struct hsi_client *cl)
+{
+        if (!hsi_port_claimed(cl))
+                return -EACCES;
+        return hsi_get_port(cl)->start_tx(cl);
+}
+
+/**
+ * hsi_stop_tx - Signal the port that the client no longer wants to transmit
+ * @cl: Pointer to the HSI client
+ *
+ * Return -errno on failure, 0 on success
+ */
+static inline int hsi_stop_tx(struct hsi_client *cl)
+{
+        if (!hsi_port_claimed(cl))
+                return -EACCES;
+        return hsi_get_port(cl)->stop_tx(cl);
+}
+#endif /* __LINUX_HSI_H__ */
diff --git a/include/linux/hsi/hsi_char.h b/include/linux/hsi/hsi_char.h
new file mode 100644
index 00000000000..76160b4f455
--- /dev/null
+++ b/include/linux/hsi/hsi_char.h
@@ -0,0 +1,63 @@
+/*
+ * Part of the HSI character device driver.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Andras Domokos <andras.domokos at nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+
+#ifndef __HSI_CHAR_H
+#define __HSI_CHAR_H
+
+#define HSI_CHAR_MAGIC          'k'
+#define HSC_IOW(num, dtype)     _IOW(HSI_CHAR_MAGIC, num, dtype)
+#define HSC_IOR(num, dtype)     _IOR(HSI_CHAR_MAGIC, num, dtype)
+#define HSC_IOWR(num, dtype)    _IOWR(HSI_CHAR_MAGIC, num, dtype)
+#define HSC_IO(num)             _IO(HSI_CHAR_MAGIC, num)
+
+#define HSC_RESET               HSC_IO(16)
+#define HSC_SET_PM              HSC_IO(17)
+#define HSC_SEND_BREAK          HSC_IO(18)
+#define HSC_SET_RX              HSC_IOW(19, struct hsc_rx_config)
+#define HSC_GET_RX              HSC_IOW(20, struct hsc_rx_config)
+#define HSC_SET_TX              HSC_IOW(21, struct hsc_tx_config)
+#define HSC_GET_TX              HSC_IOW(22, struct hsc_tx_config)
+
+#define HSC_PM_DISABLE          0
+#define HSC_PM_ENABLE           1
+
+#define HSC_MODE_STREAM         1
+#define HSC_MODE_FRAME          2
+#define HSC_FLOW_SYNC           0
+#define HSC_ARB_RR              0
+#define HSC_ARB_PRIO            1
+
+struct hsc_rx_config {
+        uint32_t mode;
+        uint32_t flow;
+        uint32_t channels;
+};
+
+struct hsc_tx_config {
+        uint32_t mode;
+        uint32_t channels;
+        uint32_t speed;
+        uint32_t arb_mode;
+};
+
+#endif /* __HSI_CHAR_H */