caif-driver: Add CAIF-SPI Protocol driver.

This patch introduces the CAIF SPI Protocol Driver for
CAIF Link Layer.

This driver implements a platform driver to accommodate for a
platform specific SPI device. A general platform driver is not
possible as there are no SPI Slave side Kernel API defined.
A sample CAIF SPI Platform device can be found in
.../Documentation/networking/caif/spi_porting.txt

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 1483 insertions, 0 deletions

diff --git a/Documentation/networking/caif/spi_porting.txt b/Documentation/networking/caif/spi_porting.txt
new file mode 100644
index 000000000000..61d7c9247453
--- /dev/null
+++ b/Documentation/networking/caif/spi_porting.txt
@@ -0,0 +1,208 @@
+- CAIF SPI porting -
+
+- CAIF SPI basics:
+
+Running CAIF over SPI needs some extra setup, owing to the nature of SPI.
+Two extra GPIOs have been added in order to negotiate the transfers
+ between the master and the slave. The minimum requirement for running
+CAIF over SPI is a SPI slave chip and two GPIOs (more details below).
+Please note that running as a slave implies that you need to keep up
+with the master clock. An overrun or underrun event is fatal.
+
+- CAIF SPI framework:
+
+To make porting as easy as possible, the CAIF SPI has been divided in
+two parts. The first part (called the interface part) deals with all
+generic functionality such as length framing, SPI frame negotiation
+and SPI frame delivery and transmission. The other part is the CAIF
+SPI slave device part, which is the module that you have to write if
+you want to run SPI CAIF on a new hardware. This part takes care of
+the physical hardware, both with regard to SPI and to GPIOs.
+
+- Implementing a CAIF SPI device:
+
+        - Functionality provided by the CAIF SPI slave device:
+
+        In order to implement a SPI device you will, as a minimum,
+        need to implement the following
+        functions:
+
+        int (*init_xfer) (struct cfspi_xfer * xfer, struct cfspi_dev *dev):
+
+        This function is called by the CAIF SPI interface to give
+        you a chance to set up your hardware to be ready to receive
+        a stream of data from the master. The xfer structure contains
+        both physical and logical adresses, as well as the total length
+        of the transfer in both directions.The dev parameter can be used
+        to map to different CAIF SPI slave devices.
+
+        void (*sig_xfer) (bool xfer, struct cfspi_dev *dev):
+
+        This function is called by the CAIF SPI interface when the output
+        (SPI_INT) GPIO needs to change state. The boolean value of the xfer
+        variable indicates whether the GPIO should be asserted (HIGH) or
+        deasserted (LOW). The dev parameter can be used to map to different CAIF
+        SPI slave devices.
+
+        - Functionality provided by the CAIF SPI interface:
+
+        void (*ss_cb) (bool assert, struct cfspi_ifc *ifc);
+
+        This function is called by the CAIF SPI slave device in order to
+        signal a change of state of the input GPIO (SS) to the interface.
+        Only active edges are mandatory to be reported.
+        This function can be called from IRQ context (recommended in order
+        not to introduce latency). The ifc parameter should be the pointer
+        returned from the platform probe function in the SPI device structure.
+
+        void (*xfer_done_cb) (struct cfspi_ifc *ifc);
+
+        This function is called by the CAIF SPI slave device in order to
+        report that a transfer is completed. This function should only be
+        called once both the transmission and the reception are completed.
+        This function can be called from IRQ context (recommended in order
+        not to introduce latency). The ifc parameter should be the pointer
+        returned from the platform probe function in the SPI device structure.
+
+        - Connecting the bits and pieces:
+
+                - Filling in the SPI slave device structure:
+
+                Connect the necessary callback functions.
+                Indicate clock speed (used to calculate toggle delays).
+                Chose a suitable name (helps debugging if you use several CAIF
+                SPI slave devices).
+                Assign your private data (can be used to map to your structure).
+
+                - Filling in the SPI slave platform device structure:
+                Add name of driver to connect to ("cfspi_sspi").
+                Assign the SPI slave device structure as platform data.
+
+- Padding:
+
+In order to optimize throughput, a number of SPI padding options are provided.
+Padding can be enabled independently for uplink and downlink transfers.
+Padding can be enabled for the head, the tail and for the total frame size.
+The padding needs to be correctly configured on both sides of the link.
+The padding can be changed via module parameters in cfspi_sspi.c or via
+the sysfs directory of the cfspi_sspi driver (before device registration).
+
+- CAIF SPI device template:
+
+/*
+ *      Copyright (C) ST-Ericsson AB 2010
+ *      Author: Daniel Martensson / Daniel.Martensson@stericsson.com
+ *      License terms: GNU General Public License (GPL), version 2.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/wait.h>
+#include <linux/interrupt.h>
+#include <linux/dma-mapping.h>
+#include <net/caif/caif_spi.h>
+
+MODULE_LICENSE("GPL");
+
+struct sspi_struct {
+        struct cfspi_dev sdev;
+        struct cfspi_xfer *xfer;
+};
+
+static struct sspi_struct slave;
+static struct platform_device slave_device;
+
+static irqreturn_t sspi_irq(int irq, void *arg)
+{
+        /* You only need to trigger on an edge to the active state of the
+         * SS signal. Once a edge is detected, the ss_cb() function should be
+         * called with the parameter assert set to true. It is OK
+         * (and even advised) to call the ss_cb() function in IRQ context in
+         * order not to add any delay. */
+
+        return IRQ_HANDLED;
+}
+
+static void sspi_complete(void *context)
+{
+        /* Normally the DMA or the SPI framework will call you back
+         * in something similar to this. The only thing you need to
+         * do is to call the xfer_done_cb() function, providing the pointer
+         * to the CAIF SPI interface. It is OK to call this function
+         * from IRQ context. */
+}
+
+static int sspi_init_xfer(struct cfspi_xfer *xfer, struct cfspi_dev *dev)
+{
+        /* Store transfer info. For a normal implementation you should
+         * set up your DMA here and make sure that you are ready to
+         * receive the data from the master SPI. */
+
+        struct sspi_struct *sspi = (struct sspi_struct *)dev->priv;
+
+        sspi->xfer = xfer;
+
+        return 0;
+}
+
+void sspi_sig_xfer(bool xfer, struct cfspi_dev *dev)
+{
+        /* If xfer is true then you should assert the SPI_INT to indicate to
+         * the master that you are ready to recieve the data from the master
+         * SPI. If xfer is false then you should de-assert SPI_INT to indicate
+         * that the transfer is done.
+         */
+
+        struct sspi_struct *sspi = (struct sspi_struct *)dev->priv;
+}
+
+static void sspi_release(struct device *dev)
+{
+        /*
+         * Here you should release your SPI device resources.
+         */
+}
+
+static int __init sspi_init(void)
+{
+        /* Here you should initialize your SPI device by providing the
+         * necessary functions, clock speed, name and private data. Once
+         * done, you can register your device with the
+         * platform_device_register() function. This function will return
+         * with the CAIF SPI interface initialized. This is probably also
+         * the place where you should set up your GPIOs, interrupts and SPI
+         * resources. */
+
+        int res = 0;
+
+        /* Initialize slave device. */
+        slave.sdev.init_xfer = sspi_init_xfer;
+        slave.sdev.sig_xfer = sspi_sig_xfer;
+        slave.sdev.clk_mhz = 13;
+        slave.sdev.priv = &slave;
+        slave.sdev.name = "spi_sspi";
+        slave_device.dev.release = sspi_release;
+
+        /* Initialize platform device. */
+        slave_device.name = "cfspi_sspi";
+        slave_device.dev.platform_data = &slave.sdev;
+
+        /* Register platform device. */
+        res = platform_device_register(&slave_device);
+        if (res) {
+                printk(KERN_WARNING "sspi_init: failed to register dev.\n");
+                return -ENODEV;
+        }
+
+        return res;
+}
+
+static void __exit sspi_exit(void)
+{
+        platform_device_del(&slave_device);
+}
+
+module_init(sspi_init);
+module_exit(sspi_exit);
diff --git a/drivers/net/caif/Kconfig b/drivers/net/caif/Kconfig
index 6f33ee453f41..631a6242b011 100644
--- a/drivers/net/caif/Kconfig
+++ b/drivers/net/caif/Kconfig
@@ -12,3 +12,22 @@ config CAIF_TTY
         The CAIF TTY transport driver is a Line Discipline (ldisc)
         identified as N_CAIF. When this ldisc is opened from user space
         it will redirect the TTY's traffic into the CAIF stack.
+
+config CAIF_SPI_SLAVE
+        tristate "CAIF SPI transport driver for slave interface"
+        depends on CAIF
+        default n
+        ---help---
+        The CAIF Link layer SPI Protocol driver for Slave SPI interface.
+        This driver implements a platform driver to accommodate for a
+        platform specific SPI device. A sample CAIF SPI Platform device is
+        provided in Documentation/networking/caif/spi_porting.txt
+
+config CAIF_SPI_SYNC
+        bool "Next command and length in start of frame"
+        depends on CAIF_SPI_SLAVE
+        default n
+        ---help---
+        Putting the next command and length in the start of the frame can
+        help to synchronize to the next transfer in case of over or under-runs.
+        This option also needs to be enabled on the modem.
diff --git a/drivers/net/caif/Makefile b/drivers/net/caif/Makefile
index e6d3ca06ecfe..3a11d619452b 100644
--- a/drivers/net/caif/Makefile
+++ b/drivers/net/caif/Makefile
@@ -4,3 +4,7 @@ endif
 
 # Serial interface
 obj-$(CONFIG_CAIF_TTY) += caif_serial.o
+
+# SPI slave physical interfaces module
+cfspi_slave-objs := caif_spi.o caif_spi_slave.o
+obj-$(CONFIG_CAIF_SPI_SLAVE) += cfspi_slave.o
diff --git a/drivers/net/caif/caif_spi.c b/drivers/net/caif/caif_spi.c
new file mode 100644
index 000000000000..03049e86e8ae
--- /dev/null
+++ b/drivers/net/caif/caif_spi.c
@@ -0,0 +1,847 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2010
+ * Contact: Sjur Brendeland / sjur.brandeland@stericsson.com
+ * Author:  Daniel Martensson / Daniel.Martensson@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2.
+ */
+
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/workqueue.h>
+#include <linux/completion.h>
+#include <linux/list.h>
+#include <linux/interrupt.h>
+#include <linux/dma-mapping.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/debugfs.h>
+#include <linux/if_arp.h>
+#include <net/caif/caif_layer.h>
+#include <net/caif/caif_spi.h>
+
+#ifndef CONFIG_CAIF_SPI_SYNC
+#define FLAVOR "Flavour: Vanilla.\n"
+#else
+#define FLAVOR "Flavour: Master CMD&LEN at start.\n"
+#endif /* CONFIG_CAIF_SPI_SYNC */
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Daniel Martensson<daniel.martensson@stericsson.com>");
+MODULE_DESCRIPTION("CAIF SPI driver");
+
+static int spi_loop;
+module_param(spi_loop, bool, S_IRUGO);
+MODULE_PARM_DESC(spi_loop, "SPI running in loopback mode.");
+
+/* SPI frame alignment. */
+module_param(spi_frm_align, int, S_IRUGO);
+MODULE_PARM_DESC(spi_frm_align, "SPI frame alignment.");
+
+/* SPI padding options. */
+module_param(spi_up_head_align, int, S_IRUGO);
+MODULE_PARM_DESC(spi_up_head_align, "SPI uplink head alignment.");
+
+module_param(spi_up_tail_align, int, S_IRUGO);
+MODULE_PARM_DESC(spi_up_tail_align, "SPI uplink tail alignment.");
+
+module_param(spi_down_head_align, int, S_IRUGO);
+MODULE_PARM_DESC(spi_down_head_align, "SPI downlink head alignment.");
+
+module_param(spi_down_tail_align, int, S_IRUGO);
+MODULE_PARM_DESC(spi_down_tail_align, "SPI downlink tail alignment.");
+
+#ifdef CONFIG_ARM
+#define BYTE_HEX_FMT "%02X"
+#else
+#define BYTE_HEX_FMT "%02hhX"
+#endif
+
+#define SPI_MAX_PAYLOAD_SIZE 4096
+/*
+ * Threshold values for the SPI packet queue. Flowcontrol will be asserted
+ * when the number of packets exceeds HIGH_WATER_MARK. It will not be
+ * deasserted before the number of packets drops below LOW_WATER_MARK.
+ */
+#define LOW_WATER_MARK   100
+#define HIGH_WATER_MARK  (LOW_WATER_MARK*5)
+
+#ifdef CONFIG_UML
+
+/*
+ * We sometimes use UML for debugging, but it cannot handle
+ * dma_alloc_coherent so we have to wrap it.
+ */
+static inline void *dma_alloc(dma_addr_t *daddr)
+{
+        return kmalloc(SPI_DMA_BUF_LEN, GFP_KERNEL);
+}
+
+static inline void dma_free(void *cpu_addr, dma_addr_t handle)
+{
+        kfree(cpu_addr);
+}
+
+#else
+
+static inline void *dma_alloc(dma_addr_t *daddr)
+{
+        return dma_alloc_coherent(NULL, SPI_DMA_BUF_LEN, daddr,
+                                GFP_KERNEL);
+}
+
+static inline void dma_free(void *cpu_addr, dma_addr_t handle)
+{
+        dma_free_coherent(NULL, SPI_DMA_BUF_LEN, cpu_addr, handle);
+}
+#endif  /* CONFIG_UML */
+
+#ifdef CONFIG_DEBUG_FS
+
+#define DEBUGFS_BUF_SIZE        4096
+
+static struct dentry *dbgfs_root;
+
+static inline void driver_debugfs_create(void)
+{
+        dbgfs_root = debugfs_create_dir(cfspi_spi_driver.driver.name, NULL);
+}
+
+static inline void driver_debugfs_remove(void)
+{
+        debugfs_remove(dbgfs_root);
+}
+
+static inline void dev_debugfs_rem(struct cfspi *cfspi)
+{
+        debugfs_remove(cfspi->dbgfs_frame);
+        debugfs_remove(cfspi->dbgfs_state);
+        debugfs_remove(cfspi->dbgfs_dir);
+}
+
+static int dbgfs_open(struct inode *inode, struct file *file)
+{
+        file->private_data = inode->i_private;
+        return 0;
+}
+
+static ssize_t dbgfs_state(struct file *file, char __user *user_buf,
+                           size_t count, loff_t *ppos)
+{
+        char *buf;
+        int len = 0;
+        ssize_t size;
+        struct cfspi *cfspi = (struct cfspi *)file->private_data;
+
+        buf = kzalloc(DEBUGFS_BUF_SIZE, GFP_KERNEL);
+        if (!buf)
+                return 0;
+
+        /* Print out debug information. */
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "CAIF SPI debug information:\n");
+
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len), FLAVOR);
+
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "STATE: %d\n", cfspi->dbg_state);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Previous CMD: 0x%x\n", cfspi->pcmd);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Current CMD: 0x%x\n", cfspi->cmd);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Previous TX len: %d\n", cfspi->tx_ppck_len);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Previous RX len: %d\n", cfspi->rx_ppck_len);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Current TX len: %d\n", cfspi->tx_cpck_len);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Current RX len: %d\n", cfspi->rx_cpck_len);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Next TX len: %d\n", cfspi->tx_npck_len);
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Next RX len: %d\n", cfspi->rx_npck_len);
+
+        size = simple_read_from_buffer(user_buf, count, ppos, buf, len);
+        kfree(buf);
+
+        return size;
+}
+
+static ssize_t print_frame(char *buf, size_t size, char *frm,
+                           size_t count, size_t cut)
+{
+        int len = 0;
+        int i;
+        for (i = 0; i < count; i++) {
+                len += snprintf((buf + len), (size - len),
+                                        "[0x" BYTE_HEX_FMT "]",
+                                        frm[i]);
+                if ((i == cut) && (count > (cut * 2))) {
+                        /* Fast forward. */
+                        i = count - cut;
+                        len += snprintf((buf + len), (size - len),
+                                        "--- %u bytes skipped ---\n",
+                                        (int)(count - (cut * 2)));
+                }
+
+                if ((!(i % 10)) && i) {
+                        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                                        "\n");
+                }
+        }
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len), "\n");
+        return len;
+}
+
+static ssize_t dbgfs_frame(struct file *file, char __user *user_buf,
+                           size_t count, loff_t *ppos)
+{
+        char *buf;
+        int len = 0;
+        ssize_t size;
+        struct cfspi *cfspi;
+
+        cfspi = (struct cfspi *)file->private_data;
+        buf = kzalloc(DEBUGFS_BUF_SIZE, GFP_KERNEL);
+        if (!buf)
+                return 0;
+
+        /* Print out debug information. */
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Current frame:\n");
+
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Tx data (Len: %d):\n", cfspi->tx_cpck_len);
+
+        len += print_frame((buf + len), (DEBUGFS_BUF_SIZE - len),
+                           cfspi->xfer.va_tx,
+                           (cfspi->tx_cpck_len + SPI_CMD_SZ), 100);
+
+        len += snprintf((buf + len), (DEBUGFS_BUF_SIZE - len),
+                        "Rx data (Len: %d):\n", cfspi->rx_cpck_len);
+
+        len += print_frame((buf + len), (DEBUGFS_BUF_SIZE - len),
+                           cfspi->xfer.va_rx,
+                           (cfspi->rx_cpck_len + SPI_CMD_SZ), 100);
+
+        size = simple_read_from_buffer(user_buf, count, ppos, buf, len);
+        kfree(buf);
+
+        return size;
+}
+
+static const struct file_operations dbgfs_state_fops = {
+        .open = dbgfs_open,
+        .read = dbgfs_state,
+        .owner = THIS_MODULE
+};
+
+static const struct file_operations dbgfs_frame_fops = {
+        .open = dbgfs_open,
+        .read = dbgfs_frame,
+        .owner = THIS_MODULE
+};
+
+static inline void dev_debugfs_add(struct cfspi *cfspi)
+{
+        cfspi->dbgfs_dir = debugfs_create_dir(cfspi->pdev->name, dbgfs_root);
+        cfspi->dbgfs_state = debugfs_create_file("state", S_IRUGO,
+                                                 cfspi->dbgfs_dir, cfspi,
+                                                 &dbgfs_state_fops);
+        cfspi->dbgfs_frame = debugfs_create_file("frame", S_IRUGO,
+                                                 cfspi->dbgfs_dir, cfspi,
+                                                 &dbgfs_frame_fops);
+}
+
+inline void cfspi_dbg_state(struct cfspi *cfspi, int state)
+{
+        cfspi->dbg_state = state;
+};
+#else
+
+static inline void driver_debugfs_create(void)
+{
+}
+
+static inline void driver_debugfs_remove(void)
+{
+}
+
+static inline void dev_debugfs_add(struct cfspi *cfspi)
+{
+}
+
+static inline void dev_debugfs_rem(struct cfspi *cfspi)
+{
+}
+
+inline void cfspi_dbg_state(struct cfspi *cfspi, int state)
+{
+}
+#endif                          /* CONFIG_DEBUG_FS */
+
+static LIST_HEAD(cfspi_list);
+static spinlock_t cfspi_list_lock;
+
+/* SPI uplink head alignment. */
+static ssize_t show_up_head_align(struct device_driver *driver, char *buf)
+{
+        return sprintf(buf, "%d\n", spi_up_head_align);
+}
+
+static DRIVER_ATTR(up_head_align, S_IRUSR, show_up_head_align, NULL);
+
+/* SPI uplink tail alignment. */
+static ssize_t show_up_tail_align(struct device_driver *driver, char *buf)
+{
+        return sprintf(buf, "%d\n", spi_up_tail_align);
+}
+
+static DRIVER_ATTR(up_tail_align, S_IRUSR, show_up_tail_align, NULL);
+
+/* SPI downlink head alignment. */
+static ssize_t show_down_head_align(struct device_driver *driver, char *buf)
+{
+        return sprintf(buf, "%d\n", spi_down_head_align);
+}
+
+static DRIVER_ATTR(down_head_align, S_IRUSR, show_down_head_align, NULL);
+
+/* SPI downlink tail alignment. */
+static ssize_t show_down_tail_align(struct device_driver *driver, char *buf)
+{
+        return sprintf(buf, "%d\n", spi_down_tail_align);
+}
+
+static DRIVER_ATTR(down_tail_align, S_IRUSR, show_down_tail_align, NULL);
+
+/* SPI frame alignment. */
+static ssize_t show_frame_align(struct device_driver *driver, char *buf)
+{
+        return sprintf(buf, "%d\n", spi_frm_align);
+}
+
+static DRIVER_ATTR(frame_align, S_IRUSR, show_frame_align, NULL);
+
+int cfspi_xmitfrm(struct cfspi *cfspi, u8 *buf, size_t len)
+{
+        u8 *dst = buf;
+        caif_assert(buf);
+
+        do {
+                struct sk_buff *skb;
+                struct caif_payload_info *info;
+                int spad = 0;
+                int epad;
+
+                skb = skb_dequeue(&cfspi->chead);
+                if (!skb)
+                        break;
+
+                /*
+                 * Calculate length of frame including SPI padding.
+                 * The payload position is found in the control buffer.
+                 */
+                info = (struct caif_payload_info *)&skb->cb;
+
+                /*
+                 * Compute head offset i.e. number of bytes to add to
+                 * get the start of the payload aligned.
+                 */
+                if (spi_up_head_align) {
+                        spad = 1 + ((info->hdr_len + 1) & spi_up_head_align);
+                        *dst = (u8)(spad - 1);
+                        dst += spad;
+                }
+
+                /* Copy in CAIF frame. */
+                skb_copy_bits(skb, 0, dst, skb->len);
+                dst += skb->len;
+                cfspi->ndev->stats.tx_packets++;
+                cfspi->ndev->stats.tx_bytes += skb->len;
+
+                /*
+                 * Compute tail offset i.e. number of bytes to add to
+                 * get the complete CAIF frame aligned.
+                 */
+                epad = (skb->len + spad) & spi_up_tail_align;
+                dst += epad;
+
+                dev_kfree_skb(skb);
+
+        } while ((dst - buf) < len);
+
+        return dst - buf;
+}
+
+int cfspi_xmitlen(struct cfspi *cfspi)
+{
+        struct sk_buff *skb = NULL;
+        int frm_len = 0;
+        int pkts = 0;
+
+        /*
+         * Decommit previously commited frames.
+         * skb_queue_splice_tail(&cfspi->chead,&cfspi->qhead)
+         */
+        while (skb_peek(&cfspi->chead)) {
+                skb = skb_dequeue_tail(&cfspi->chead);
+                skb_queue_head(&cfspi->qhead, skb);
+        }
+
+        do {
+                struct caif_payload_info *info = NULL;
+                int spad = 0;
+                int epad = 0;
+
+                skb = skb_dequeue(&cfspi->qhead);
+                if (!skb)
+                        break;
+
+                /*
+                 * Calculate length of frame including SPI padding.
+                 * The payload position is found in the control buffer.
+                 */
+                info = (struct caif_payload_info *)&skb->cb;
+
+                /*
+                 * Compute head offset i.e. number of bytes to add to
+                 * get the start of the payload aligned.
+                 */
+                if (spi_up_head_align)
+                        spad = 1 + ((info->hdr_len + 1) & spi_up_head_align);
+
+                /*
+                 * Compute tail offset i.e. number of bytes to add to
+                 * get the complete CAIF frame aligned.
+                 */
+                epad = (skb->len + spad) & spi_up_tail_align;
+
+                if ((skb->len + spad + epad + frm_len) <= CAIF_MAX_SPI_FRAME) {
+                        skb_queue_tail(&cfspi->chead, skb);
+                        pkts++;
+                        frm_len += skb->len + spad + epad;
+                } else {
+                        /* Put back packet. */
+                        skb_queue_head(&cfspi->qhead, skb);
+                }
+        } while (pkts <= CAIF_MAX_SPI_PKTS);
+
+        /*
+         * Send flow on if previously sent flow off
+         * and now go below the low water mark
+         */
+        if (cfspi->flow_off_sent && cfspi->qhead.qlen < cfspi->qd_low_mark &&
+                cfspi->cfdev.flowctrl) {
+                cfspi->flow_off_sent = 0;
+                cfspi->cfdev.flowctrl(cfspi->ndev, 1);
+        }
+
+        return frm_len;
+}
+
+static void cfspi_ss_cb(bool assert, struct cfspi_ifc *ifc)
+{
+        struct cfspi *cfspi = (struct cfspi *)ifc->priv;
+
+        if (!in_interrupt())
+                spin_lock(&cfspi->lock);
+        if (assert) {
+                set_bit(SPI_SS_ON, &cfspi->state);
+                set_bit(SPI_XFER, &cfspi->state);
+        } else {
+                set_bit(SPI_SS_OFF, &cfspi->state);
+        }
+        if (!in_interrupt())
+                spin_unlock(&cfspi->lock);
+
+        /* Wake up the xfer thread. */
+        wake_up_interruptible(&cfspi->wait);
+}
+
+static void cfspi_xfer_done_cb(struct cfspi_ifc *ifc)
+{
+        struct cfspi *cfspi = (struct cfspi *)ifc->priv;
+
+        /* Transfer done, complete work queue */
+        complete(&cfspi->comp);
+}
+
+static int cfspi_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+        struct cfspi *cfspi = NULL;
+        unsigned long flags;
+        if (!dev)
+                return -EINVAL;
+
+        cfspi = netdev_priv(dev);
+
+        skb_queue_tail(&cfspi->qhead, skb);
+
+        spin_lock_irqsave(&cfspi->lock, flags);
+        if (!test_and_set_bit(SPI_XFER, &cfspi->state)) {
+                /* Wake up xfer thread. */
+                wake_up_interruptible(&cfspi->wait);
+        }
+        spin_unlock_irqrestore(&cfspi->lock, flags);
+
+        /* Send flow off if number of bytes is above high water mark */
+        if (!cfspi->flow_off_sent &&
+                cfspi->qhead.qlen > cfspi->qd_high_mark &&
+                cfspi->cfdev.flowctrl) {
+                cfspi->flow_off_sent = 1;
+                cfspi->cfdev.flowctrl(cfspi->ndev, 0);
+        }
+
+        return 0;
+}
+
+int cfspi_rxfrm(struct cfspi *cfspi, u8 *buf, size_t len)
+{
+        u8 *src = buf;
+
+        caif_assert(buf != NULL);
+
+        do {
+                int res;
+                struct sk_buff *skb = NULL;
+                int spad = 0;
+                int epad = 0;
+                u8 *dst = NULL;
+                int pkt_len = 0;
+
+                /*
+                 * Compute head offset i.e. number of bytes added to
+                 * get the start of the payload aligned.
+                 */
+                if (spi_down_head_align) {
+                        spad = 1 + *src;
+                        src += spad;
+                }
+
+                /* Read length of CAIF frame (little endian). */
+                pkt_len = *src;
+                pkt_len |= ((*(src+1)) << 8) & 0xFF00;
+                pkt_len += 2;   /* Add FCS fields. */
+
+                /* Get a suitable caif packet and copy in data. */
+
+                skb = netdev_alloc_skb(cfspi->ndev, pkt_len + 1);
+                caif_assert(skb != NULL);
+
+                dst = skb_put(skb, pkt_len);
+                memcpy(dst, src, pkt_len);
+                src += pkt_len;
+
+                skb->protocol = htons(ETH_P_CAIF);
+                skb_reset_mac_header(skb);
+                skb->dev = cfspi->ndev;
+
+                /*
+                 * Push received packet up the stack.
+                 */
+                if (!spi_loop)
+                        res = netif_rx_ni(skb);
+                else
+                        res = cfspi_xmit(skb, cfspi->ndev);
+
+                if (!res) {
+                        cfspi->ndev->stats.rx_packets++;
+                        cfspi->ndev->stats.rx_bytes += pkt_len;
+                } else
+                        cfspi->ndev->stats.rx_dropped++;
+
+                /*
+                 * Compute tail offset i.e. number of bytes added to
+                 * get the complete CAIF frame aligned.
+                 */
+                epad = (pkt_len + spad) & spi_down_tail_align;
+                src += epad;
+        } while ((src - buf) < len);
+
+        return src - buf;
+}
+
+static int cfspi_open(struct net_device *dev)
+{
+        netif_wake_queue(dev);
+        return 0;
+}
+
+static int cfspi_close(struct net_device *dev)
+{
+        netif_stop_queue(dev);
+        return 0;
+}
+static const struct net_device_ops cfspi_ops = {
+        .ndo_open = cfspi_open,
+        .ndo_stop = cfspi_close,
+        .ndo_start_xmit = cfspi_xmit
+};
+
+static void cfspi_setup(struct net_device *dev)
+{
+        struct cfspi *cfspi = netdev_priv(dev);
+        dev->features = 0;
+        dev->netdev_ops = &cfspi_ops;
+        dev->type = ARPHRD_CAIF;
+        dev->flags = IFF_NOARP | IFF_POINTOPOINT;
+        dev->tx_queue_len = 0;
+        dev->mtu = SPI_MAX_PAYLOAD_SIZE;
+        dev->destructor = free_netdev;
+        skb_queue_head_init(&cfspi->qhead);
+        skb_queue_head_init(&cfspi->chead);
+        cfspi->cfdev.link_select = CAIF_LINK_HIGH_BANDW;
+        cfspi->cfdev.use_frag = false;
+        cfspi->cfdev.use_stx = false;
+        cfspi->cfdev.use_fcs = false;
+        cfspi->ndev = dev;
+}
+
+int cfspi_spi_probe(struct platform_device *pdev)
+{
+        struct cfspi *cfspi = NULL;
+        struct net_device *ndev;
+        struct cfspi_dev *dev;
+        int res;
+        dev = (struct cfspi_dev *)pdev->dev.platform_data;
+
+        ndev = alloc_netdev(sizeof(struct cfspi),
+                        "cfspi%d", cfspi_setup);
+        if (!dev)
+                return -ENODEV;
+
+        cfspi = netdev_priv(ndev);
+        netif_stop_queue(ndev);
+        cfspi->ndev = ndev;
+        cfspi->pdev = pdev;
+
+        /* Set flow info */
+        cfspi->flow_off_sent = 0;
+        cfspi->qd_low_mark = LOW_WATER_MARK;
+        cfspi->qd_high_mark = HIGH_WATER_MARK;
+
+        /* Assign the SPI device. */
+        cfspi->dev = dev;
+        /* Assign the device ifc to this SPI interface. */
+        dev->ifc = &cfspi->ifc;
+
+        /* Allocate DMA buffers. */
+        cfspi->xfer.va_tx = dma_alloc(&cfspi->xfer.pa_tx);
+        if (!cfspi->xfer.va_tx) {
+                printk(KERN_WARNING
+                       "CFSPI: failed to allocate dma TX buffer.\n");
+                res = -ENODEV;
+                goto err_dma_alloc_tx;
+        }
+
+        cfspi->xfer.va_rx = dma_alloc(&cfspi->xfer.pa_rx);
+
+        if (!cfspi->xfer.va_rx) {
+                printk(KERN_WARNING
+                       "CFSPI: failed to allocate dma TX buffer.\n");
+                res = -ENODEV;
+                goto err_dma_alloc_rx;
+        }
+
+        /* Initialize the work queue. */
+        INIT_WORK(&cfspi->work, cfspi_xfer);
+
+        /* Initialize spin locks. */
+        spin_lock_init(&cfspi->lock);
+
+        /* Initialize flow control state. */
+        cfspi->flow_stop = false;
+
+        /* Initialize wait queue. */
+        init_waitqueue_head(&cfspi->wait);
+
+        /* Create work thread. */
+        cfspi->wq = create_singlethread_workqueue(dev->name);
+        if (!cfspi->wq) {
+                printk(KERN_WARNING "CFSPI: failed to create work queue.\n");
+                res = -ENODEV;
+                goto err_create_wq;
+        }
+
+        /* Initialize work queue. */
+        init_completion(&cfspi->comp);
+
+        /* Create debugfs entries. */
+        dev_debugfs_add(cfspi);
+
+        /* Set up the ifc. */
+        cfspi->ifc.ss_cb = cfspi_ss_cb;
+        cfspi->ifc.xfer_done_cb = cfspi_xfer_done_cb;
+        cfspi->ifc.priv = cfspi;
+
+        /* Add CAIF SPI device to list. */
+        spin_lock(&cfspi_list_lock);
+        list_add_tail(&cfspi->list, &cfspi_list);
+        spin_unlock(&cfspi_list_lock);
+
+        /* Schedule the work queue. */
+        queue_work(cfspi->wq, &cfspi->work);
+
+        /* Register network device. */
+        res = register_netdev(ndev);
+        if (res) {
+                printk(KERN_ERR "CFSPI: Reg. error: %d.\n", res);
+                goto err_net_reg;
+        }
+        return res;
+
+ err_net_reg:
+        dev_debugfs_rem(cfspi);
+        set_bit(SPI_TERMINATE, &cfspi->state);
+        wake_up_interruptible(&cfspi->wait);
+        destroy_workqueue(cfspi->wq);
+ err_create_wq:
+        dma_free(cfspi->xfer.va_rx, cfspi->xfer.pa_rx);
+ err_dma_alloc_rx:
+        dma_free(cfspi->xfer.va_tx, cfspi->xfer.pa_tx);
+ err_dma_alloc_tx:
+        free_netdev(ndev);
+
+        return res;
+}
+
+int cfspi_spi_remove(struct platform_device *pdev)
+{
+        struct list_head *list_node;
+        struct list_head *n;
+        struct cfspi *cfspi = NULL;
+        struct cfspi_dev *dev;
+
+        dev = (struct cfspi_dev *)pdev->dev.platform_data;
+        spin_lock(&cfspi_list_lock);
+        list_for_each_safe(list_node, n, &cfspi_list) {
+                cfspi = list_entry(list_node, struct cfspi, list);
+                /* Find the corresponding device. */
+                if (cfspi->dev == dev) {
+                        /* Remove from list. */
+                        list_del(list_node);
+                        /* Free DMA buffers. */
+                        dma_free(cfspi->xfer.va_rx, cfspi->xfer.pa_rx);
+                        dma_free(cfspi->xfer.va_tx, cfspi->xfer.pa_tx);
+                        set_bit(SPI_TERMINATE, &cfspi->state);
+                        wake_up_interruptible(&cfspi->wait);
+                        destroy_workqueue(cfspi->wq);
+                        /* Destroy debugfs directory and files. */
+                        dev_debugfs_rem(cfspi);
+                        unregister_netdev(cfspi->ndev);
+                        spin_unlock(&cfspi_list_lock);
+                        return 0;
+                }
+        }
+        spin_unlock(&cfspi_list_lock);
+        return -ENODEV;
+}
+
+static void __exit cfspi_exit_module(void)
+{
+        struct list_head *list_node;
+        struct list_head *n;
+        struct cfspi *cfspi = NULL;
+
+        list_for_each_safe(list_node, n, &cfspi_list) {
+                cfspi = list_entry(list_node, struct cfspi, list);
+                platform_device_unregister(cfspi->pdev);
+        }
+
+        /* Destroy sysfs files. */
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_up_head_align);
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_up_tail_align);
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_down_head_align);
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_down_tail_align);
+        driver_remove_file(&cfspi_spi_driver.driver, &driver_attr_frame_align);
+        /* Unregister platform driver. */
+        platform_driver_unregister(&cfspi_spi_driver);
+        /* Destroy debugfs root directory. */
+        driver_debugfs_remove();
+}
+
+static int __init cfspi_init_module(void)
+{
+        int result;
+
+        /* Initialize spin lock. */
+        spin_lock_init(&cfspi_list_lock);
+
+        /* Register platform driver. */
+        result = platform_driver_register(&cfspi_spi_driver);
+        if (result) {
+                printk(KERN_ERR "Could not register platform SPI driver.\n");
+                goto err_dev_register;
+        }
+
+        /* Create sysfs files. */
+        result =
+            driver_create_file(&cfspi_spi_driver.driver,
+                               &driver_attr_up_head_align);
+        if (result) {
+                printk(KERN_ERR "Sysfs creation failed 1.\n");
+                goto err_create_up_head_align;
+        }
+
+        result =
+            driver_create_file(&cfspi_spi_driver.driver,
+                               &driver_attr_up_tail_align);
+        if (result) {
+                printk(KERN_ERR "Sysfs creation failed 2.\n");
+                goto err_create_up_tail_align;
+        }
+
+        result =
+            driver_create_file(&cfspi_spi_driver.driver,
+                               &driver_attr_down_head_align);
+        if (result) {
+                printk(KERN_ERR "Sysfs creation failed 3.\n");
+                goto err_create_down_head_align;
+        }
+
+        result =
+            driver_create_file(&cfspi_spi_driver.driver,
+                               &driver_attr_down_tail_align);
+        if (result) {
+                printk(KERN_ERR "Sysfs creation failed 4.\n");
+                goto err_create_down_tail_align;
+        }
+
+        result =
+            driver_create_file(&cfspi_spi_driver.driver,
+                               &driver_attr_frame_align);
+        if (result) {
+                printk(KERN_ERR "Sysfs creation failed 5.\n");
+                goto err_create_frame_align;
+        }
+        driver_debugfs_create();
+        return result;
+
+ err_create_frame_align:
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_down_tail_align);
+ err_create_down_tail_align:
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_down_head_align);
+ err_create_down_head_align:
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_up_tail_align);
+ err_create_up_tail_align:
+        driver_remove_file(&cfspi_spi_driver.driver,
+                           &driver_attr_up_head_align);
+ err_create_up_head_align:
+ err_dev_register:
+        return result;
+}
+
+module_init(cfspi_init_module);
+module_exit(cfspi_exit_module);
diff --git a/drivers/net/caif/caif_spi_slave.c b/drivers/net/caif/caif_spi_slave.c
new file mode 100644
index 000000000000..077ccf840edf
--- /dev/null
+++ b/drivers/net/caif/caif_spi_slave.c
@@ -0,0 +1,252 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2010
+ * Contact: Sjur Brendeland / sjur.brandeland@stericsson.com
+ * Author:  Daniel Martensson / Daniel.Martensson@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2.
+ */
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/semaphore.h>
+#include <linux/workqueue.h>
+#include <linux/completion.h>
+#include <linux/list.h>
+#include <linux/interrupt.h>
+#include <linux/dma-mapping.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/debugfs.h>
+#include <net/caif/caif_spi.h>
+
+#ifndef CONFIG_CAIF_SPI_SYNC
+#define SPI_DATA_POS SPI_CMD_SZ
+static inline int forward_to_spi_cmd(struct cfspi *cfspi)
+{
+        return cfspi->rx_cpck_len;
+}
+#else
+#define SPI_DATA_POS 0
+static inline int forward_to_spi_cmd(struct cfspi *cfspi)
+{
+        return 0;
+}
+#endif
+
+int spi_frm_align = 2;
+int spi_up_head_align = 1;
+int spi_up_tail_align;
+int spi_down_head_align = 3;
+int spi_down_tail_align = 1;
+
+#ifdef CONFIG_DEBUG_FS
+static inline void debugfs_store_prev(struct cfspi *cfspi)
+{
+        /* Store previous command for debugging reasons.*/
+        cfspi->pcmd = cfspi->cmd;
+        /* Store previous transfer. */
+        cfspi->tx_ppck_len = cfspi->tx_cpck_len;
+        cfspi->rx_ppck_len = cfspi->rx_cpck_len;
+}
+#else
+static inline void debugfs_store_prev(struct cfspi *cfspi)
+{
+}
+#endif
+
+void cfspi_xfer(struct work_struct *work)
+{
+        struct cfspi *cfspi;
+        u8 *ptr = NULL;
+        unsigned long flags;
+        int ret;
+        cfspi = container_of(work, struct cfspi, work);
+
+        /* Initialize state. */
+        cfspi->cmd = SPI_CMD_EOT;
+
+        for (;;) {
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_WAITING);
+
+                /* Wait for master talk or transmit event. */
+                wait_event_interruptible(cfspi->wait,
+                                 test_bit(SPI_XFER, &cfspi->state) ||
+                                 test_bit(SPI_TERMINATE, &cfspi->state));
+
+                if (test_bit(SPI_TERMINATE, &cfspi->state))
+                        return;
+
+#if CFSPI_DBG_PREFILL
+                /* Prefill buffers for easier debugging. */
+                memset(cfspi->xfer.va_tx, 0xFF, SPI_DMA_BUF_LEN);
+                memset(cfspi->xfer.va_rx, 0xFF, SPI_DMA_BUF_LEN);
+#endif  /* CFSPI_DBG_PREFILL */
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_AWAKE);
+
+        /* Check whether we have a committed frame. */
+                if (cfspi->tx_cpck_len) {
+                        int len;
+
+                        cfspi_dbg_state(cfspi, CFSPI_STATE_FETCH_PKT);
+
+                        /* Copy commited SPI frames after the SPI indication. */
+                        ptr = (u8 *) cfspi->xfer.va_tx;
+                        ptr += SPI_IND_SZ;
+                        len = cfspi_xmitfrm(cfspi, ptr, cfspi->tx_cpck_len);
+                        WARN_ON(len != cfspi->tx_cpck_len);
+        }
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_GET_NEXT);
+
+                /* Get length of next frame to commit. */
+                cfspi->tx_npck_len = cfspi_xmitlen(cfspi);
+
+                WARN_ON(cfspi->tx_npck_len > SPI_DMA_BUF_LEN);
+
+                /*
+                 * Add indication and length at the beginning of the frame,
+                 * using little endian.
+                 */
+                ptr = (u8 *) cfspi->xfer.va_tx;
+                *ptr++ = SPI_CMD_IND;
+                *ptr++ = (SPI_CMD_IND  & 0xFF00) >> 8;
+                *ptr++ = cfspi->tx_npck_len & 0x00FF;
+                *ptr++ = (cfspi->tx_npck_len & 0xFF00) >> 8;
+
+                /* Calculate length of DMAs. */
+                cfspi->xfer.tx_dma_len = cfspi->tx_cpck_len + SPI_IND_SZ;
+                cfspi->xfer.rx_dma_len = cfspi->rx_cpck_len + SPI_CMD_SZ;
+
+                /* Add SPI TX frame alignment padding, if necessary. */
+                if (cfspi->tx_cpck_len &&
+                        (cfspi->xfer.tx_dma_len % spi_frm_align)) {
+
+                        cfspi->xfer.tx_dma_len += spi_frm_align -
+                            (cfspi->xfer.tx_dma_len % spi_frm_align);
+                }
+
+                /* Add SPI RX frame alignment padding, if necessary. */
+                if (cfspi->rx_cpck_len &&
+                        (cfspi->xfer.rx_dma_len % spi_frm_align)) {
+
+                        cfspi->xfer.rx_dma_len += spi_frm_align -
+                            (cfspi->xfer.rx_dma_len % spi_frm_align);
+                }
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_INIT_XFER);
+
+                /* Start transfer. */
+                ret = cfspi->dev->init_xfer(&cfspi->xfer, cfspi->dev);
+                WARN_ON(ret);
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_ACTIVE);
+
+                /*
+                 * TODO: We might be able to make an assumption if this is the
+                 * first loop. Make sure that minimum toggle time is respected.
+                 */
+                udelay(MIN_TRANSITION_TIME_USEC);
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_SIG_ACTIVE);
+
+                /* Signal that we are ready to recieve data. */
+                cfspi->dev->sig_xfer(true, cfspi->dev);
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_XFER_DONE);
+
+                /* Wait for transfer completion. */
+                wait_for_completion(&cfspi->comp);
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_XFER_DONE);
+
+                if (cfspi->cmd == SPI_CMD_EOT) {
+                        /*
+                         * Clear the master talk bit. A xfer is always at
+                         *  least two bursts.
+                         */
+                        clear_bit(SPI_SS_ON, &cfspi->state);
+                }
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_WAIT_INACTIVE);
+
+                /* Make sure that the minimum toggle time is respected. */
+                if (SPI_XFER_TIME_USEC(cfspi->xfer.tx_dma_len,
+                                        cfspi->dev->clk_mhz) <
+                        MIN_TRANSITION_TIME_USEC) {
+
+                        udelay(MIN_TRANSITION_TIME_USEC -
+                                SPI_XFER_TIME_USEC
+                                (cfspi->xfer.tx_dma_len, cfspi->dev->clk_mhz));
+                }
+
+                cfspi_dbg_state(cfspi, CFSPI_STATE_SIG_INACTIVE);
+
+                /* De-assert transfer signal. */
+                cfspi->dev->sig_xfer(false, cfspi->dev);
+
+                /* Check whether we received a CAIF packet. */
+                if (cfspi->rx_cpck_len) {
+                        int len;
+
+                        cfspi_dbg_state(cfspi, CFSPI_STATE_DELIVER_PKT);
+
+                        /* Parse SPI frame. */
+                        ptr = ((u8 *)(cfspi->xfer.va_rx + SPI_DATA_POS));
+
+                        len = cfspi_rxfrm(cfspi, ptr, cfspi->rx_cpck_len);
+                        WARN_ON(len != cfspi->rx_cpck_len);
+                }
+
+                /* Check the next SPI command and length. */
+                ptr = (u8 *) cfspi->xfer.va_rx;
+
+                ptr += forward_to_spi_cmd(cfspi);
+
+                cfspi->cmd = *ptr++;
+                cfspi->cmd |= ((*ptr++) << 8) & 0xFF00;
+                cfspi->rx_npck_len = *ptr++;
+                cfspi->rx_npck_len |= ((*ptr++) << 8) & 0xFF00;
+
+                WARN_ON(cfspi->rx_npck_len > SPI_DMA_BUF_LEN);
+                WARN_ON(cfspi->cmd > SPI_CMD_EOT);
+
+                debugfs_store_prev(cfspi);
+
+                /* Check whether the master issued an EOT command. */
+                if (cfspi->cmd == SPI_CMD_EOT) {
+                        /* Reset state. */
+                        cfspi->tx_cpck_len = 0;
+                        cfspi->rx_cpck_len = 0;
+                } else {
+                        /* Update state. */
+                        cfspi->tx_cpck_len = cfspi->tx_npck_len;
+                        cfspi->rx_cpck_len = cfspi->rx_npck_len;
+                }
+
+                /*
+                 * Check whether we need to clear the xfer bit.
+                 * Spin lock needed for packet insertion.
+                 * Test and clear of different bits
+                 * are not supported.
+                 */
+                spin_lock_irqsave(&cfspi->lock, flags);
+                if (cfspi->cmd == SPI_CMD_EOT && !cfspi_xmitlen(cfspi)
+                        && !test_bit(SPI_SS_ON, &cfspi->state))
+                        clear_bit(SPI_XFER, &cfspi->state);
+
+                spin_unlock_irqrestore(&cfspi->lock, flags);
+        }
+}
+
+struct platform_driver cfspi_spi_driver = {
+        .probe = cfspi_spi_probe,
+        .remove = cfspi_spi_remove,
+        .driver = {
+                   .name = "cfspi_sspi",
+                   .owner = THIS_MODULE,
+                   },
+};
diff --git a/include/net/caif/caif_spi.h b/include/net/caif/caif_spi.h
new file mode 100644
index 000000000000..ce4570dff020
--- /dev/null
+++ b/include/net/caif/caif_spi.h
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2010
+ * Author:      Daniel Martensson / Daniel.Martensson@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#ifndef CAIF_SPI_H_
+#define CAIF_SPI_H_
+
+#include <net/caif/caif_device.h>
+
+#define SPI_CMD_WR                      0x00
+#define SPI_CMD_RD                      0x01
+#define SPI_CMD_EOT                     0x02
+#define SPI_CMD_IND                     0x04
+
+#define SPI_DMA_BUF_LEN                 8192
+
+#define WL_SZ                           2       /* 16 bits. */
+#define SPI_CMD_SZ                      4       /* 32 bits. */
+#define SPI_IND_SZ                      4       /* 32 bits. */
+
+#define SPI_XFER                        0
+#define SPI_SS_ON                       1
+#define SPI_SS_OFF                      2
+#define SPI_TERMINATE                   3
+
+/* Minimum time between different levels is 50 microseconds. */
+#define MIN_TRANSITION_TIME_USEC        50
+
+/* Defines for calculating duration of SPI transfers for a particular
+ * number of bytes.
+ */
+#define SPI_MASTER_CLK_MHZ              13
+#define SPI_XFER_TIME_USEC(bytes, clk) (((bytes) * 8) / clk)
+
+/* Normally this should be aligned on the modem in order to benefit from full
+ * duplex transfers. However a size of 8188 provokes errors when running with
+ * the modem. These errors occur when packet sizes approaches 4 kB of data.
+ */
+#define CAIF_MAX_SPI_FRAME 4092
+
+/* Maximum number of uplink CAIF frames that can reside in the same SPI frame.
+ * This number should correspond with the modem setting. The application side
+ * CAIF accepts any number of embedded downlink CAIF frames.
+ */
+#define CAIF_MAX_SPI_PKTS 9
+
+/* Decides if SPI buffers should be prefilled with 0xFF pattern for easier
+ * debugging. Both TX and RX buffers will be filled before the transfer.
+ */
+#define CFSPI_DBG_PREFILL               0
+
+/* Structure describing a SPI transfer. */
+struct cfspi_xfer {
+        u16 tx_dma_len;
+        u16 rx_dma_len;
+        void *va_tx;
+        dma_addr_t pa_tx;
+        void *va_rx;
+        dma_addr_t pa_rx;
+};
+
+/* Structure implemented by the SPI interface. */
+struct cfspi_ifc {
+        void (*ss_cb) (bool assert, struct cfspi_ifc *ifc);
+        void (*xfer_done_cb) (struct cfspi_ifc *ifc);
+        void *priv;
+};
+
+/* Structure implemented by SPI clients. */
+struct cfspi_dev {
+        int (*init_xfer) (struct cfspi_xfer *xfer, struct cfspi_dev *dev);
+        void (*sig_xfer) (bool xfer, struct cfspi_dev *dev);
+        struct cfspi_ifc *ifc;
+        char *name;
+        u32 clk_mhz;
+        void *priv;
+};
+
+/* Enumeration describing the CAIF SPI state. */
+enum cfspi_state {
+        CFSPI_STATE_WAITING = 0,
+        CFSPI_STATE_AWAKE,
+        CFSPI_STATE_FETCH_PKT,
+        CFSPI_STATE_GET_NEXT,
+        CFSPI_STATE_INIT_XFER,
+        CFSPI_STATE_WAIT_ACTIVE,
+        CFSPI_STATE_SIG_ACTIVE,
+        CFSPI_STATE_WAIT_XFER_DONE,
+        CFSPI_STATE_XFER_DONE,
+        CFSPI_STATE_WAIT_INACTIVE,
+        CFSPI_STATE_SIG_INACTIVE,
+        CFSPI_STATE_DELIVER_PKT,
+        CFSPI_STATE_MAX,
+};
+
+/* Structure implemented by SPI physical interfaces. */
+struct cfspi {
+        struct caif_dev_common cfdev;
+        struct net_device *ndev;
+        struct platform_device *pdev;
+        struct sk_buff_head qhead;
+        struct sk_buff_head chead;
+        u16 cmd;
+        u16 tx_cpck_len;
+        u16 tx_npck_len;
+        u16 rx_cpck_len;
+        u16 rx_npck_len;
+        struct cfspi_ifc ifc;
+        struct cfspi_xfer xfer;
+        struct cfspi_dev *dev;
+        unsigned long state;
+        struct work_struct work;
+        struct workqueue_struct *wq;
+        struct list_head list;
+        int    flow_off_sent;
+        u32 qd_low_mark;
+        u32 qd_high_mark;
+        struct completion comp;
+        wait_queue_head_t wait;
+        spinlock_t lock;
+        bool flow_stop;
+#ifdef CONFIG_DEBUG_FS
+        enum cfspi_state dbg_state;
+        u16 pcmd;
+        u16 tx_ppck_len;
+        u16 rx_ppck_len;
+        struct dentry *dbgfs_dir;
+        struct dentry *dbgfs_state;
+        struct dentry *dbgfs_frame;
+#endif                          /* CONFIG_DEBUG_FS */
+};
+
+extern int spi_frm_align;
+extern int spi_up_head_align;
+extern int spi_up_tail_align;
+extern int spi_down_head_align;
+extern int spi_down_tail_align;
+extern struct platform_driver cfspi_spi_driver;
+
+void cfspi_dbg_state(struct cfspi *cfspi, int state);
+int cfspi_xmitfrm(struct cfspi *cfspi, u8 *buf, size_t len);
+int cfspi_xmitlen(struct cfspi *cfspi);
+int cfspi_rxfrm(struct cfspi *cfspi, u8 *buf, size_t len);
+int cfspi_spi_remove(struct platform_device *pdev);
+int cfspi_spi_probe(struct platform_device *pdev);
+int cfspi_xmitfrm(struct cfspi *cfspi, u8 *buf, size_t len);
+int cfspi_xmitlen(struct cfspi *cfspi);
+int cfspi_rxfrm(struct cfspi *cfspi, u8 *buf, size_t len);
+void cfspi_xfer(struct work_struct *work);
+
+#endif                          /* CAIF_SPI_H_ */