rpmsg: Introduce Qualcomm SMD backend

This introduces a new rpmsg backend for the Qualcomm SMD system,
allowing communication with various remote processors found in Qualcomm
platforms. The implementation is based on, and intends to replace,
drivers/soc/qcom/smd.c with the necessary adaptions for fitting with the
rpmsg core.

Based on original work by Sricharan R <sricharan@codeaurora.org>

Cc: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

3 files changed, 1445 insertions, 0 deletions

diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
index 40614be88c97..9ba5a2e5c930 100644
--- a/drivers/rpmsg/Kconfig
+++ b/drivers/rpmsg/Kconfig
@@ -4,6 +4,16 @@ menu "Rpmsg drivers"
 config RPMSG
         tristate
 
+config RPMSG_QCOM_SMD
+        tristate "Qualcomm Shared Memory Driver (SMD)"
+        depends on QCOM_SMEM
+        depends on !QCOM_SMD
+        select RPMSG
+        help
+          Say y here to enable support for the Qualcomm Shared Memory Driver
+          providing communication channels to remote processors in Qualcomm
+          platforms.
+
 config RPMSG_VIRTIO
         tristate
         select RPMSG
diff --git a/drivers/rpmsg/Makefile b/drivers/rpmsg/Makefile
index c48ea55ad380..ae9c9132cf76 100644
--- a/drivers/rpmsg/Makefile
+++ b/drivers/rpmsg/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_RPMSG)             += rpmsg_core.o
+obj-$(CONFIG_RPMSG_QCOM_SMD)    += qcom_smd.o
 obj-$(CONFIG_RPMSG_VIRTIO)      += virtio_rpmsg_bus.o
diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
new file mode 100644
index 000000000000..06fef2b4c814
--- /dev/null
+++ b/drivers/rpmsg/qcom_smd.c
@@ -0,0 +1,1434 @@
+/*
+ * Copyright (c) 2015, Sony Mobile Communications AB.
+ * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only 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.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/soc/qcom/smem.h>
+#include <linux/wait.h>
+#include <linux/rpmsg.h>
+
+#include "rpmsg_internal.h"
+
+/*
+ * The Qualcomm Shared Memory communication solution provides point-to-point
+ * channels for clients to send and receive streaming or packet based data.
+ *
+ * Each channel consists of a control item (channel info) and a ring buffer
+ * pair. The channel info carry information related to channel state, flow
+ * control and the offsets within the ring buffer.
+ *
+ * All allocated channels are listed in an allocation table, identifying the
+ * pair of items by name, type and remote processor.
+ *
+ * Upon creating a new channel the remote processor allocates channel info and
+ * ring buffer items from the smem heap and populate the allocation table. An
+ * interrupt is sent to the other end of the channel and a scan for new
+ * channels should be done. A channel never goes away, it will only change
+ * state.
+ *
+ * The remote processor signals it intent for bring up the communication
+ * channel by setting the state of its end of the channel to "opening" and
+ * sends out an interrupt. We detect this change and register a smd device to
+ * consume the channel. Upon finding a consumer we finish the handshake and the
+ * channel is up.
+ *
+ * Upon closing a channel, the remote processor will update the state of its
+ * end of the channel and signal us, we will then unregister any attached
+ * device and close our end of the channel.
+ *
+ * Devices attached to a channel can use the qcom_smd_send function to push
+ * data to the channel, this is done by copying the data into the tx ring
+ * buffer, updating the pointers in the channel info and signaling the remote
+ * processor.
+ *
+ * The remote processor does the equivalent when it transfer data and upon
+ * receiving the interrupt we check the channel info for new data and delivers
+ * this to the attached device. If the device is not ready to receive the data
+ * we leave it in the ring buffer for now.
+ */
+
+struct smd_channel_info;
+struct smd_channel_info_pair;
+struct smd_channel_info_word;
+struct smd_channel_info_word_pair;
+
+static const struct rpmsg_endpoint_ops qcom_smd_endpoint_ops;
+
+#define SMD_ALLOC_TBL_COUNT     2
+#define SMD_ALLOC_TBL_SIZE      64
+
+/*
+ * This lists the various smem heap items relevant for the allocation table and
+ * smd channel entries.
+ */
+static const struct {
+        unsigned alloc_tbl_id;
+        unsigned info_base_id;
+        unsigned fifo_base_id;
+} smem_items[SMD_ALLOC_TBL_COUNT] = {
+        {
+                .alloc_tbl_id = 13,
+                .info_base_id = 14,
+                .fifo_base_id = 338
+        },
+        {
+                .alloc_tbl_id = 266,
+                .info_base_id = 138,
+                .fifo_base_id = 202,
+        },
+};
+
+/**
+ * struct qcom_smd_edge - representing a remote processor
+ * @of_node:            of_node handle for information related to this edge
+ * @edge_id:            identifier of this edge
+ * @remote_pid:         identifier of remote processor
+ * @irq:                interrupt for signals on this edge
+ * @ipc_regmap:         regmap handle holding the outgoing ipc register
+ * @ipc_offset:         offset within @ipc_regmap of the register for ipc
+ * @ipc_bit:            bit in the register at @ipc_offset of @ipc_regmap
+ * @channels:           list of all channels detected on this edge
+ * @channels_lock:      guard for modifications of @channels
+ * @allocated:          array of bitmaps representing already allocated channels
+ * @smem_available:     last available amount of smem triggering a channel scan
+ * @scan_work:          work item for discovering new channels
+ * @state_work:         work item for edge state changes
+ */
+struct qcom_smd_edge {
+        struct device dev;
+
+        struct device_node *of_node;
+        unsigned edge_id;
+        unsigned remote_pid;
+
+        int irq;
+
+        struct regmap *ipc_regmap;
+        int ipc_offset;
+        int ipc_bit;
+
+        struct list_head channels;
+        spinlock_t channels_lock;
+
+        DECLARE_BITMAP(allocated[SMD_ALLOC_TBL_COUNT], SMD_ALLOC_TBL_SIZE);
+
+        unsigned smem_available;
+
+        wait_queue_head_t new_channel_event;
+
+        struct work_struct scan_work;
+        struct work_struct state_work;
+};
+
+/*
+ * SMD channel states.
+ */
+enum smd_channel_state {
+        SMD_CHANNEL_CLOSED,
+        SMD_CHANNEL_OPENING,
+        SMD_CHANNEL_OPENED,
+        SMD_CHANNEL_FLUSHING,
+        SMD_CHANNEL_CLOSING,
+        SMD_CHANNEL_RESET,
+        SMD_CHANNEL_RESET_OPENING
+};
+
+struct qcom_smd_device {
+        struct rpmsg_device rpdev;
+
+        struct qcom_smd_edge *edge;
+};
+
+struct qcom_smd_endpoint {
+        struct rpmsg_endpoint ept;
+
+        struct qcom_smd_channel *qsch;
+};
+
+#define to_smd_device(_rpdev)   container_of(_rpdev, struct qcom_smd_device, rpdev)
+#define to_smd_edge(d)          container_of(d, struct qcom_smd_edge, dev)
+#define to_smd_endpoint(ept)    container_of(ept, struct qcom_smd_endpoint, ept)
+
+/**
+ * struct qcom_smd_channel - smd channel struct
+ * @edge:               qcom_smd_edge this channel is living on
+ * @qsdev:              reference to a associated smd client device
+ * @name:               name of the channel
+ * @state:              local state of the channel
+ * @remote_state:       remote state of the channel
+ * @info:               byte aligned outgoing/incoming channel info
+ * @info_word:          word aligned outgoing/incoming channel info
+ * @tx_lock:            lock to make writes to the channel mutually exclusive
+ * @fblockread_event:   wakeup event tied to tx fBLOCKREADINTR
+ * @tx_fifo:            pointer to the outgoing ring buffer
+ * @rx_fifo:            pointer to the incoming ring buffer
+ * @fifo_size:          size of each ring buffer
+ * @bounce_buffer:      bounce buffer for reading wrapped packets
+ * @cb:                 callback function registered for this channel
+ * @recv_lock:          guard for rx info modifications and cb pointer
+ * @pkt_size:           size of the currently handled packet
+ * @list:               lite entry for @channels in qcom_smd_edge
+ */
+struct qcom_smd_channel {
+        struct qcom_smd_edge *edge;
+
+        struct qcom_smd_endpoint *qsept;
+        bool registered;
+
+        char *name;
+        enum smd_channel_state state;
+        enum smd_channel_state remote_state;
+
+        struct smd_channel_info_pair *info;
+        struct smd_channel_info_word_pair *info_word;
+
+        struct mutex tx_lock;
+        wait_queue_head_t fblockread_event;
+
+        void *tx_fifo;
+        void *rx_fifo;
+        int fifo_size;
+
+        void *bounce_buffer;
+
+        spinlock_t recv_lock;
+
+        int pkt_size;
+
+        void *drvdata;
+
+        struct list_head list;
+};
+
+/*
+ * Format of the smd_info smem items, for byte aligned channels.
+ */
+struct smd_channel_info {
+        __le32 state;
+        u8  fDSR;
+        u8  fCTS;
+        u8  fCD;
+        u8  fRI;
+        u8  fHEAD;
+        u8  fTAIL;
+        u8  fSTATE;
+        u8  fBLOCKREADINTR;
+        __le32 tail;
+        __le32 head;
+};
+
+struct smd_channel_info_pair {
+        struct smd_channel_info tx;
+        struct smd_channel_info rx;
+};
+
+/*
+ * Format of the smd_info smem items, for word aligned channels.
+ */
+struct smd_channel_info_word {
+        __le32 state;
+        __le32 fDSR;
+        __le32 fCTS;
+        __le32 fCD;
+        __le32 fRI;
+        __le32 fHEAD;
+        __le32 fTAIL;
+        __le32 fSTATE;
+        __le32 fBLOCKREADINTR;
+        __le32 tail;
+        __le32 head;
+};
+
+struct smd_channel_info_word_pair {
+        struct smd_channel_info_word tx;
+        struct smd_channel_info_word rx;
+};
+
+#define GET_RX_CHANNEL_FLAG(channel, param)                                  \
+        ({                                                                   \
+                BUILD_BUG_ON(sizeof(channel->info->rx.param) != sizeof(u8)); \
+                channel->info_word ?                                         \
+                        le32_to_cpu(channel->info_word->rx.param) :          \
+                        channel->info->rx.param;                             \
+        })
+
+#define GET_RX_CHANNEL_INFO(channel, param)                                   \
+        ({                                                                    \
+                BUILD_BUG_ON(sizeof(channel->info->rx.param) != sizeof(u32)); \
+                le32_to_cpu(channel->info_word ?                              \
+                        channel->info_word->rx.param :                        \
+                        channel->info->rx.param);                             \
+        })
+
+#define SET_RX_CHANNEL_FLAG(channel, param, value)                           \
+        ({                                                                   \
+                BUILD_BUG_ON(sizeof(channel->info->rx.param) != sizeof(u8)); \
+                if (channel->info_word)                                      \
+                        channel->info_word->rx.param = cpu_to_le32(value);   \
+                else                                                         \
+                        channel->info->rx.param = value;                     \
+        })
+
+#define SET_RX_CHANNEL_INFO(channel, param, value)                            \
+        ({                                                                    \
+                BUILD_BUG_ON(sizeof(channel->info->rx.param) != sizeof(u32)); \
+                if (channel->info_word)                                       \
+                        channel->info_word->rx.param = cpu_to_le32(value);    \
+                else                                                          \
+                        channel->info->rx.param = cpu_to_le32(value);         \
+        })
+
+#define GET_TX_CHANNEL_FLAG(channel, param)                                  \
+        ({                                                                   \
+                BUILD_BUG_ON(sizeof(channel->info->tx.param) != sizeof(u8)); \
+                channel->info_word ?                                         \
+                        le32_to_cpu(channel->info_word->tx.param) :          \
+                        channel->info->tx.param;                             \
+        })
+
+#define GET_TX_CHANNEL_INFO(channel, param)                                   \
+        ({                                                                    \
+                BUILD_BUG_ON(sizeof(channel->info->tx.param) != sizeof(u32)); \
+                le32_to_cpu(channel->info_word ?                              \
+                        channel->info_word->tx.param :                        \
+                        channel->info->tx.param);                             \
+        })
+
+#define SET_TX_CHANNEL_FLAG(channel, param, value)                           \
+        ({                                                                   \
+                BUILD_BUG_ON(sizeof(channel->info->tx.param) != sizeof(u8)); \
+                if (channel->info_word)                                      \
+                        channel->info_word->tx.param = cpu_to_le32(value);   \
+                else                                                         \
+                        channel->info->tx.param = value;                     \
+        })
+
+#define SET_TX_CHANNEL_INFO(channel, param, value)                            \
+        ({                                                                    \
+                BUILD_BUG_ON(sizeof(channel->info->tx.param) != sizeof(u32)); \
+                if (channel->info_word)                                       \
+                        channel->info_word->tx.param = cpu_to_le32(value);   \
+                else                                                          \
+                        channel->info->tx.param = cpu_to_le32(value);         \
+        })
+
+/**
+ * struct qcom_smd_alloc_entry - channel allocation entry
+ * @name:       channel name
+ * @cid:        channel index
+ * @flags:      channel flags and edge id
+ * @ref_count:  reference count of the channel
+ */
+struct qcom_smd_alloc_entry {
+        u8 name[20];
+        __le32 cid;
+        __le32 flags;
+        __le32 ref_count;
+} __packed;
+
+#define SMD_CHANNEL_FLAGS_EDGE_MASK     0xff
+#define SMD_CHANNEL_FLAGS_STREAM        BIT(8)
+#define SMD_CHANNEL_FLAGS_PACKET        BIT(9)
+
+/*
+ * Each smd packet contains a 20 byte header, with the first 4 being the length
+ * of the packet.
+ */
+#define SMD_PACKET_HEADER_LEN   20
+
+/*
+ * Signal the remote processor associated with 'channel'.
+ */
+static void qcom_smd_signal_channel(struct qcom_smd_channel *channel)
+{
+        struct qcom_smd_edge *edge = channel->edge;
+
+        regmap_write(edge->ipc_regmap, edge->ipc_offset, BIT(edge->ipc_bit));
+}
+
+/*
+ * Initialize the tx channel info
+ */
+static void qcom_smd_channel_reset(struct qcom_smd_channel *channel)
+{
+        SET_TX_CHANNEL_INFO(channel, state, SMD_CHANNEL_CLOSED);
+        SET_TX_CHANNEL_FLAG(channel, fDSR, 0);
+        SET_TX_CHANNEL_FLAG(channel, fCTS, 0);
+        SET_TX_CHANNEL_FLAG(channel, fCD, 0);
+        SET_TX_CHANNEL_FLAG(channel, fRI, 0);
+        SET_TX_CHANNEL_FLAG(channel, fHEAD, 0);
+        SET_TX_CHANNEL_FLAG(channel, fTAIL, 0);
+        SET_TX_CHANNEL_FLAG(channel, fSTATE, 1);
+        SET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR, 1);
+        SET_TX_CHANNEL_INFO(channel, head, 0);
+        SET_RX_CHANNEL_INFO(channel, tail, 0);
+
+        qcom_smd_signal_channel(channel);
+
+        channel->state = SMD_CHANNEL_CLOSED;
+        channel->pkt_size = 0;
+}
+
+/*
+ * Set the callback for a channel, with appropriate locking
+ */
+static void qcom_smd_channel_set_callback(struct qcom_smd_channel *channel,
+                                          rpmsg_rx_cb_t cb)
+{
+        struct rpmsg_endpoint *ept = &channel->qsept->ept;
+        unsigned long flags;
+
+        spin_lock_irqsave(&channel->recv_lock, flags);
+        ept->cb = cb;
+        spin_unlock_irqrestore(&channel->recv_lock, flags);
+};
+
+/*
+ * Calculate the amount of data available in the rx fifo
+ */
+static size_t qcom_smd_channel_get_rx_avail(struct qcom_smd_channel *channel)
+{
+        unsigned head;
+        unsigned tail;
+
+        head = GET_RX_CHANNEL_INFO(channel, head);
+        tail = GET_RX_CHANNEL_INFO(channel, tail);
+
+        return (head - tail) & (channel->fifo_size - 1);
+}
+
+/*
+ * Set tx channel state and inform the remote processor
+ */
+static void qcom_smd_channel_set_state(struct qcom_smd_channel *channel,
+                                       int state)
+{
+        struct qcom_smd_edge *edge = channel->edge;
+        bool is_open = state == SMD_CHANNEL_OPENED;
+
+        if (channel->state == state)
+                return;
+
+        dev_dbg(&edge->dev, "set_state(%s, %d)\n", channel->name, state);
+
+        SET_TX_CHANNEL_FLAG(channel, fDSR, is_open);
+        SET_TX_CHANNEL_FLAG(channel, fCTS, is_open);
+        SET_TX_CHANNEL_FLAG(channel, fCD, is_open);
+
+        SET_TX_CHANNEL_INFO(channel, state, state);
+        SET_TX_CHANNEL_FLAG(channel, fSTATE, 1);
+
+        channel->state = state;
+        qcom_smd_signal_channel(channel);
+}
+
+/*
+ * Copy count bytes of data using 32bit accesses, if that's required.
+ */
+static void smd_copy_to_fifo(void __iomem *dst,
+                             const void *src,
+                             size_t count,
+                             bool word_aligned)
+{
+        if (word_aligned) {
+                __iowrite32_copy(dst, src, count / sizeof(u32));
+        } else {
+                memcpy_toio(dst, src, count);
+        }
+}
+
+/*
+ * Copy count bytes of data using 32bit accesses, if that is required.
+ */
+static void smd_copy_from_fifo(void *dst,
+                               const void __iomem *src,
+                               size_t count,
+                               bool word_aligned)
+{
+        if (word_aligned) {
+                __ioread32_copy(dst, src, count / sizeof(u32));
+        } else {
+                memcpy_fromio(dst, src, count);
+        }
+}
+
+/*
+ * Read count bytes of data from the rx fifo into buf, but don't advance the
+ * tail.
+ */
+static size_t qcom_smd_channel_peek(struct qcom_smd_channel *channel,
+                                    void *buf, size_t count)
+{
+        bool word_aligned;
+        unsigned tail;
+        size_t len;
+
+        word_aligned = channel->info_word;
+        tail = GET_RX_CHANNEL_INFO(channel, tail);
+
+        len = min_t(size_t, count, channel->fifo_size - tail);
+        if (len) {
+                smd_copy_from_fifo(buf,
+                                   channel->rx_fifo + tail,
+                                   len,
+                                   word_aligned);
+        }
+
+        if (len != count) {
+                smd_copy_from_fifo(buf + len,
+                                   channel->rx_fifo,
+                                   count - len,
+                                   word_aligned);
+        }
+
+        return count;
+}
+
+/*
+ * Advance the rx tail by count bytes.
+ */
+static void qcom_smd_channel_advance(struct qcom_smd_channel *channel,
+                                     size_t count)
+{
+        unsigned tail;
+
+        tail = GET_RX_CHANNEL_INFO(channel, tail);
+        tail += count;
+        tail &= (channel->fifo_size - 1);
+        SET_RX_CHANNEL_INFO(channel, tail, tail);
+}
+
+/*
+ * Read out a single packet from the rx fifo and deliver it to the device
+ */
+static int qcom_smd_channel_recv_single(struct qcom_smd_channel *channel)
+{
+        struct rpmsg_endpoint *ept = &channel->qsept->ept;
+        unsigned tail;
+        size_t len;
+        void *ptr;
+        int ret;
+
+        tail = GET_RX_CHANNEL_INFO(channel, tail);
+
+        /* Use bounce buffer if the data wraps */
+        if (tail + channel->pkt_size >= channel->fifo_size) {
+                ptr = channel->bounce_buffer;
+                len = qcom_smd_channel_peek(channel, ptr, channel->pkt_size);
+        } else {
+                ptr = channel->rx_fifo + tail;
+                len = channel->pkt_size;
+        }
+
+        ret = ept->cb(ept->rpdev, ptr, len, ept->priv, RPMSG_ADDR_ANY);
+        if (ret < 0)
+                return ret;
+
+        /* Only forward the tail if the client consumed the data */
+        qcom_smd_channel_advance(channel, len);
+
+        channel->pkt_size = 0;
+
+        return 0;
+}
+
+/*
+ * Per channel interrupt handling
+ */
+static bool qcom_smd_channel_intr(struct qcom_smd_channel *channel)
+{
+        bool need_state_scan = false;
+        int remote_state;
+        __le32 pktlen;
+        int avail;
+        int ret;
+
+        /* Handle state changes */
+        remote_state = GET_RX_CHANNEL_INFO(channel, state);
+        if (remote_state != channel->remote_state) {
+                channel->remote_state = remote_state;
+                need_state_scan = true;
+        }
+        /* Indicate that we have seen any state change */
+        SET_RX_CHANNEL_FLAG(channel, fSTATE, 0);
+
+        /* Signal waiting qcom_smd_send() about the interrupt */
+        if (!GET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR))
+                wake_up_interruptible(&channel->fblockread_event);
+
+        /* Don't consume any data until we've opened the channel */
+        if (channel->state != SMD_CHANNEL_OPENED)
+                goto out;
+
+        /* Indicate that we've seen the new data */
+        SET_RX_CHANNEL_FLAG(channel, fHEAD, 0);
+
+        /* Consume data */
+        for (;;) {
+                avail = qcom_smd_channel_get_rx_avail(channel);
+
+                if (!channel->pkt_size && avail >= SMD_PACKET_HEADER_LEN) {
+                        qcom_smd_channel_peek(channel, &pktlen, sizeof(pktlen));
+                        qcom_smd_channel_advance(channel, SMD_PACKET_HEADER_LEN);
+                        channel->pkt_size = le32_to_cpu(pktlen);
+                } else if (channel->pkt_size && avail >= channel->pkt_size) {
+                        ret = qcom_smd_channel_recv_single(channel);
+                        if (ret)
+                                break;
+                } else {
+                        break;
+                }
+        }
+
+        /* Indicate that we have seen and updated tail */
+        SET_RX_CHANNEL_FLAG(channel, fTAIL, 1);
+
+        /* Signal the remote that we've consumed the data (if requested) */
+        if (!GET_RX_CHANNEL_FLAG(channel, fBLOCKREADINTR)) {
+                /* Ensure ordering of channel info updates */
+                wmb();
+
+                qcom_smd_signal_channel(channel);
+        }
+
+out:
+        return need_state_scan;
+}
+
+/*
+ * The edge interrupts are triggered by the remote processor on state changes,
+ * channel info updates or when new channels are created.
+ */
+static irqreturn_t qcom_smd_edge_intr(int irq, void *data)
+{
+        struct qcom_smd_edge *edge = data;
+        struct qcom_smd_channel *channel;
+        unsigned available;
+        bool kick_scanner = false;
+        bool kick_state = false;
+
+        /*
+         * Handle state changes or data on each of the channels on this edge
+         */
+        spin_lock(&edge->channels_lock);
+        list_for_each_entry(channel, &edge->channels, list) {
+                spin_lock(&channel->recv_lock);
+                kick_state |= qcom_smd_channel_intr(channel);
+                spin_unlock(&channel->recv_lock);
+        }
+        spin_unlock(&edge->channels_lock);
+
+        /*
+         * Creating a new channel requires allocating an smem entry, so we only
+         * have to scan if the amount of available space in smem have changed
+         * since last scan.
+         */
+        available = qcom_smem_get_free_space(edge->remote_pid);
+        if (available != edge->smem_available) {
+                edge->smem_available = available;
+                kick_scanner = true;
+        }
+
+        if (kick_scanner)
+                schedule_work(&edge->scan_work);
+        if (kick_state)
+                schedule_work(&edge->state_work);
+
+        return IRQ_HANDLED;
+}
+
+/*
+ * Calculate how much space is available in the tx fifo.
+ */
+static size_t qcom_smd_get_tx_avail(struct qcom_smd_channel *channel)
+{
+        unsigned head;
+        unsigned tail;
+        unsigned mask = channel->fifo_size - 1;
+
+        head = GET_TX_CHANNEL_INFO(channel, head);
+        tail = GET_TX_CHANNEL_INFO(channel, tail);
+
+        return mask - ((head - tail) & mask);
+}
+
+/*
+ * Write count bytes of data into channel, possibly wrapping in the ring buffer
+ */
+static int qcom_smd_write_fifo(struct qcom_smd_channel *channel,
+                               const void *data,
+                               size_t count)
+{
+        bool word_aligned;
+        unsigned head;
+        size_t len;
+
+        word_aligned = channel->info_word;
+        head = GET_TX_CHANNEL_INFO(channel, head);
+
+        len = min_t(size_t, count, channel->fifo_size - head);
+        if (len) {
+                smd_copy_to_fifo(channel->tx_fifo + head,
+                                 data,
+                                 len,
+                                 word_aligned);
+        }
+
+        if (len != count) {
+                smd_copy_to_fifo(channel->tx_fifo,
+                                 data + len,
+                                 count - len,
+                                 word_aligned);
+        }
+
+        head += count;
+        head &= (channel->fifo_size - 1);
+        SET_TX_CHANNEL_INFO(channel, head, head);
+
+        return count;
+}
+
+/**
+ * qcom_smd_send - write data to smd channel
+ * @channel:    channel handle
+ * @data:       buffer of data to write
+ * @len:        number of bytes to write
+ *
+ * This is a blocking write of len bytes into the channel's tx ring buffer and
+ * signal the remote end. It will sleep until there is enough space available
+ * in the tx buffer, utilizing the fBLOCKREADINTR signaling mechanism to avoid
+ * polling.
+ */
+static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
+                           int len, bool wait)
+{
+        __le32 hdr[5] = { cpu_to_le32(len), };
+        int tlen = sizeof(hdr) + len;
+        int ret;
+
+        /* Word aligned channels only accept word size aligned data */
+        if (channel->info_word && len % 4)
+                return -EINVAL;
+
+        /* Reject packets that are too big */
+        if (tlen >= channel->fifo_size)
+                return -EINVAL;
+
+        ret = mutex_lock_interruptible(&channel->tx_lock);
+        if (ret)
+                return ret;
+
+        while (qcom_smd_get_tx_avail(channel) < tlen) {
+                if (!wait) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+
+                if (channel->state != SMD_CHANNEL_OPENED) {
+                        ret = -EPIPE;
+                        goto out;
+                }
+
+                SET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR, 0);
+
+                ret = wait_event_interruptible(channel->fblockread_event,
+                                       qcom_smd_get_tx_avail(channel) >= tlen ||
+                                       channel->state != SMD_CHANNEL_OPENED);
+                if (ret)
+                        goto out;
+
+                SET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR, 1);
+        }
+
+        SET_TX_CHANNEL_FLAG(channel, fTAIL, 0);
+
+        qcom_smd_write_fifo(channel, hdr, sizeof(hdr));
+        qcom_smd_write_fifo(channel, data, len);
+
+        SET_TX_CHANNEL_FLAG(channel, fHEAD, 1);
+
+        /* Ensure ordering of channel info updates */
+        wmb();
+
+        qcom_smd_signal_channel(channel);
+
+out:
+        mutex_unlock(&channel->tx_lock);
+
+        return ret;
+}
+
+/*
+ * Helper for opening a channel
+ */
+static int qcom_smd_channel_open(struct qcom_smd_channel *channel,
+                                 rpmsg_rx_cb_t cb)
+{
+        size_t bb_size;
+
+        /*
+         * Packets are maximum 4k, but reduce if the fifo is smaller
+         */
+        bb_size = min(channel->fifo_size, SZ_4K);
+        channel->bounce_buffer = kmalloc(bb_size, GFP_KERNEL);
+        if (!channel->bounce_buffer)
+                return -ENOMEM;
+
+        qcom_smd_channel_set_callback(channel, cb);
+        qcom_smd_channel_set_state(channel, SMD_CHANNEL_OPENING);
+        qcom_smd_channel_set_state(channel, SMD_CHANNEL_OPENED);
+
+        return 0;
+}
+
+/*
+ * Helper for closing and resetting a channel
+ */
+static void qcom_smd_channel_close(struct qcom_smd_channel *channel)
+{
+        qcom_smd_channel_set_callback(channel, NULL);
+
+        kfree(channel->bounce_buffer);
+        channel->bounce_buffer = NULL;
+
+        qcom_smd_channel_set_state(channel, SMD_CHANNEL_CLOSED);
+        qcom_smd_channel_reset(channel);
+}
+
+static struct qcom_smd_channel *
+qcom_smd_find_channel(struct qcom_smd_edge *edge, const char *name)
+{
+        struct qcom_smd_channel *channel;
+        struct qcom_smd_channel *ret = NULL;
+        unsigned long flags;
+        unsigned state;
+
+        spin_lock_irqsave(&edge->channels_lock, flags);
+        list_for_each_entry(channel, &edge->channels, list) {
+                if (strcmp(channel->name, name))
+                        continue;
+
+                state = GET_RX_CHANNEL_INFO(channel, state);
+                if (state != SMD_CHANNEL_OPENING &&
+                    state != SMD_CHANNEL_OPENED)
+                        continue;
+
+                ret = channel;
+                break;
+        }
+        spin_unlock_irqrestore(&edge->channels_lock, flags);
+
+        return ret;
+}
+
+static void __ept_release(struct kref *kref)
+{
+        struct rpmsg_endpoint *ept = container_of(kref, struct rpmsg_endpoint,
+                                                  refcount);
+        kfree(to_smd_endpoint(ept));
+}
+
+static struct rpmsg_endpoint *qcom_smd_create_ept(struct rpmsg_device *rpdev,
+                                                  rpmsg_rx_cb_t cb, void *priv,
+                                                  struct rpmsg_channel_info chinfo)
+{
+        struct qcom_smd_endpoint *qsept;
+        struct qcom_smd_channel *channel;
+        struct qcom_smd_device *qsdev = to_smd_device(rpdev);
+        struct qcom_smd_edge *edge = qsdev->edge;
+        struct rpmsg_endpoint *ept;
+        const char *name = chinfo.name;
+        int ret;
+
+        /* Wait up to HZ for the channel to appear */
+        ret = wait_event_interruptible_timeout(edge->new_channel_event,
+                        (channel = qcom_smd_find_channel(edge, name)) != NULL,
+                        HZ);
+        if (!ret)
+                return NULL;
+
+        if (channel->state != SMD_CHANNEL_CLOSED) {
+                dev_err(&rpdev->dev, "channel %s is busy\n", channel->name);
+                return NULL;
+        }
+
+        qsept = kzalloc(sizeof(*qsept), GFP_KERNEL);
+        if (!qsept)
+                return NULL;
+
+        ept = &qsept->ept;
+
+        kref_init(&ept->refcount);
+
+        ept->rpdev = rpdev;
+        ept->cb = cb;
+        ept->priv = priv;
+        ept->ops = &qcom_smd_endpoint_ops;
+
+        channel->qsept = qsept;
+        qsept->qsch = channel;
+
+        ret = qcom_smd_channel_open(channel, cb);
+        if (ret)
+                goto free_ept;
+
+        return ept;
+
+free_ept:
+        channel->qsept = NULL;
+        kref_put(&ept->refcount, __ept_release);
+        return NULL;
+}
+
+static void qcom_smd_destroy_ept(struct rpmsg_endpoint *ept)
+{
+        struct qcom_smd_endpoint *qsept = to_smd_endpoint(ept);
+        struct qcom_smd_channel *ch = qsept->qsch;
+
+        qcom_smd_channel_close(ch);
+        ch->qsept = NULL;
+        kref_put(&ept->refcount, __ept_release);
+}
+
+static int qcom_smd_send(struct rpmsg_endpoint *ept, void *data, int len)
+{
+        struct qcom_smd_endpoint *qsept = to_smd_endpoint(ept);
+
+        return __qcom_smd_send(qsept->qsch, data, len, true);
+}
+
+static int qcom_smd_trysend(struct rpmsg_endpoint *ept, void *data, int len)
+{
+        struct qcom_smd_endpoint *qsept = to_smd_endpoint(ept);
+
+        return __qcom_smd_send(qsept->qsch, data, len, false);
+}
+
+/*
+ * Finds the device_node for the smd child interested in this channel.
+ */
+static struct device_node *qcom_smd_match_channel(struct device_node *edge_node,
+                                                  const char *channel)
+{
+        struct device_node *child;
+        const char *name;
+        const char *key;
+        int ret;
+
+        for_each_available_child_of_node(edge_node, child) {
+                key = "qcom,smd-channels";
+                ret = of_property_read_string(child, key, &name);
+                if (ret)
+                        continue;
+
+                if (strcmp(name, channel) == 0)
+                        return child;
+        }
+
+        return NULL;
+}
+
+static const struct rpmsg_device_ops qcom_smd_device_ops = {
+        .create_ept = qcom_smd_create_ept,
+};
+
+static const struct rpmsg_endpoint_ops qcom_smd_endpoint_ops = {
+        .destroy_ept = qcom_smd_destroy_ept,
+        .send = qcom_smd_send,
+        .trysend = qcom_smd_trysend,
+};
+
+/*
+ * Create a smd client device for channel that is being opened.
+ */
+static int qcom_smd_create_device(struct qcom_smd_channel *channel)
+{
+        struct qcom_smd_device *qsdev;
+        struct rpmsg_device *rpdev;
+        struct qcom_smd_edge *edge = channel->edge;
+
+        dev_dbg(&edge->dev, "registering '%s'\n", channel->name);
+
+        qsdev = kzalloc(sizeof(*qsdev), GFP_KERNEL);
+        if (!qsdev)
+                return -ENOMEM;
+
+        /* Link qsdev to our SMD edge */
+        qsdev->edge = edge;
+
+        /* Assign callbacks for rpmsg_device */
+        qsdev->rpdev.ops = &qcom_smd_device_ops;
+
+        /* Assign public information to the rpmsg_device */
+        rpdev = &qsdev->rpdev;
+        strncpy(rpdev->id.name, channel->name, RPMSG_NAME_SIZE);
+        rpdev->src = RPMSG_ADDR_ANY;
+        rpdev->dst = RPMSG_ADDR_ANY;
+
+        rpdev->dev.of_node = qcom_smd_match_channel(edge->of_node, channel->name);
+        rpdev->dev.parent = &edge->dev;
+
+        return rpmsg_register_device(rpdev);
+}
+
+/*
+ * Allocate the qcom_smd_channel object for a newly found smd channel,
+ * retrieving and validating the smem items involved.
+ */
+static struct qcom_smd_channel *qcom_smd_create_channel(struct qcom_smd_edge *edge,
+                                                        unsigned smem_info_item,
+                                                        unsigned smem_fifo_item,
+                                                        char *name)
+{
+        struct qcom_smd_channel *channel;
+        size_t fifo_size;
+        size_t info_size;
+        void *fifo_base;
+        void *info;
+        int ret;
+
+        channel = devm_kzalloc(&edge->dev, sizeof(*channel), GFP_KERNEL);
+        if (!channel)
+                return ERR_PTR(-ENOMEM);
+
+        channel->edge = edge;
+        channel->name = devm_kstrdup(&edge->dev, name, GFP_KERNEL);
+        if (!channel->name)
+                return ERR_PTR(-ENOMEM);
+
+        mutex_init(&channel->tx_lock);
+        spin_lock_init(&channel->recv_lock);
+        init_waitqueue_head(&channel->fblockread_event);
+
+        info = qcom_smem_get(edge->remote_pid, smem_info_item, &info_size);
+        if (IS_ERR(info)) {
+                ret = PTR_ERR(info);
+                goto free_name_and_channel;
+        }
+
+        /*
+         * Use the size of the item to figure out which channel info struct to
+         * use.
+         */
+        if (info_size == 2 * sizeof(struct smd_channel_info_word)) {
+                channel->info_word = info;
+        } else if (info_size == 2 * sizeof(struct smd_channel_info)) {
+                channel->info = info;
+        } else {
+                dev_err(&edge->dev,
+                        "channel info of size %zu not supported\n", info_size);
+                ret = -EINVAL;
+                goto free_name_and_channel;
+        }
+
+        fifo_base = qcom_smem_get(edge->remote_pid, smem_fifo_item, &fifo_size);
+        if (IS_ERR(fifo_base)) {
+                ret =  PTR_ERR(fifo_base);
+                goto free_name_and_channel;
+        }
+
+        /* The channel consist of a rx and tx fifo of equal size */
+        fifo_size /= 2;
+
+        dev_dbg(&edge->dev, "new channel '%s' info-size: %zu fifo-size: %zu\n",
+                          name, info_size, fifo_size);
+
+        channel->tx_fifo = fifo_base;
+        channel->rx_fifo = fifo_base + fifo_size;
+        channel->fifo_size = fifo_size;
+
+        qcom_smd_channel_reset(channel);
+
+        return channel;
+
+free_name_and_channel:
+        devm_kfree(&edge->dev, channel->name);
+        devm_kfree(&edge->dev, channel);
+
+        return ERR_PTR(ret);
+}
+
+/*
+ * Scans the allocation table for any newly allocated channels, calls
+ * qcom_smd_create_channel() to create representations of these and add
+ * them to the edge's list of channels.
+ */
+static void qcom_channel_scan_worker(struct work_struct *work)
+{
+        struct qcom_smd_edge *edge = container_of(work, struct qcom_smd_edge, scan_work);
+        struct qcom_smd_alloc_entry *alloc_tbl;
+        struct qcom_smd_alloc_entry *entry;
+        struct qcom_smd_channel *channel;
+        unsigned long flags;
+        unsigned fifo_id;
+        unsigned info_id;
+        int tbl;
+        int i;
+        u32 eflags, cid;
+
+        for (tbl = 0; tbl < SMD_ALLOC_TBL_COUNT; tbl++) {
+                alloc_tbl = qcom_smem_get(edge->remote_pid,
+                                    smem_items[tbl].alloc_tbl_id, NULL);
+                if (IS_ERR(alloc_tbl))
+                        continue;
+
+                for (i = 0; i < SMD_ALLOC_TBL_SIZE; i++) {
+                        entry = &alloc_tbl[i];
+                        eflags = le32_to_cpu(entry->flags);
+                        if (test_bit(i, edge->allocated[tbl]))
+                                continue;
+
+                        if (entry->ref_count == 0)
+                                continue;
+
+                        if (!entry->name[0])
+                                continue;
+
+                        if (!(eflags & SMD_CHANNEL_FLAGS_PACKET))
+                                continue;
+
+                        if ((eflags & SMD_CHANNEL_FLAGS_EDGE_MASK) != edge->edge_id)
+                                continue;
+
+                        cid = le32_to_cpu(entry->cid);
+                        info_id = smem_items[tbl].info_base_id + cid;
+                        fifo_id = smem_items[tbl].fifo_base_id + cid;
+
+                        channel = qcom_smd_create_channel(edge, info_id, fifo_id, entry->name);
+                        if (IS_ERR(channel))
+                                continue;
+
+                        spin_lock_irqsave(&edge->channels_lock, flags);
+                        list_add(&channel->list, &edge->channels);
+                        spin_unlock_irqrestore(&edge->channels_lock, flags);
+
+                        dev_dbg(&edge->dev, "new channel found: '%s'\n", channel->name);
+                        set_bit(i, edge->allocated[tbl]);
+
+                        wake_up_interruptible(&edge->new_channel_event);
+                }
+        }
+
+        schedule_work(&edge->state_work);
+}
+
+/*
+ * This per edge worker scans smem for any new channels and register these. It
+ * then scans all registered channels for state changes that should be handled
+ * by creating or destroying smd client devices for the registered channels.
+ *
+ * LOCKING: edge->channels_lock only needs to cover the list operations, as the
+ * worker is killed before any channels are deallocated
+ */
+static void qcom_channel_state_worker(struct work_struct *work)
+{
+        struct qcom_smd_channel *channel;
+        struct qcom_smd_edge *edge = container_of(work,
+                                                  struct qcom_smd_edge,
+                                                  state_work);
+        struct rpmsg_channel_info chinfo;
+        unsigned remote_state;
+        unsigned long flags;
+
+        /*
+         * Register a device for any closed channel where the remote processor
+         * is showing interest in opening the channel.
+         */
+        spin_lock_irqsave(&edge->channels_lock, flags);
+        list_for_each_entry(channel, &edge->channels, list) {
+                if (channel->state != SMD_CHANNEL_CLOSED)
+                        continue;
+
+                remote_state = GET_RX_CHANNEL_INFO(channel, state);
+                if (remote_state != SMD_CHANNEL_OPENING &&
+                    remote_state != SMD_CHANNEL_OPENED)
+                        continue;
+
+                if (channel->registered)
+                        continue;
+
+                spin_unlock_irqrestore(&edge->channels_lock, flags);
+                qcom_smd_create_device(channel);
+                channel->registered = true;
+                spin_lock_irqsave(&edge->channels_lock, flags);
+
+                channel->registered = true;
+        }
+
+        /*
+         * Unregister the device for any channel that is opened where the
+         * remote processor is closing the channel.
+         */
+        list_for_each_entry(channel, &edge->channels, list) {
+                if (channel->state != SMD_CHANNEL_OPENING &&
+                    channel->state != SMD_CHANNEL_OPENED)
+                        continue;
+
+                remote_state = GET_RX_CHANNEL_INFO(channel, state);
+                if (remote_state == SMD_CHANNEL_OPENING ||
+                    remote_state == SMD_CHANNEL_OPENED)
+                        continue;
+
+                spin_unlock_irqrestore(&edge->channels_lock, flags);
+
+                strncpy(chinfo.name, channel->name, sizeof(chinfo.name));
+                chinfo.src = RPMSG_ADDR_ANY;
+                chinfo.dst = RPMSG_ADDR_ANY;
+                rpmsg_unregister_device(&edge->dev, &chinfo);
+                channel->registered = false;
+                spin_lock_irqsave(&edge->channels_lock, flags);
+        }
+        spin_unlock_irqrestore(&edge->channels_lock, flags);
+}
+
+/*
+ * Parses an of_node describing an edge.
+ */
+static int qcom_smd_parse_edge(struct device *dev,
+                               struct device_node *node,
+                               struct qcom_smd_edge *edge)
+{
+        struct device_node *syscon_np;
+        const char *key;
+        int irq;
+        int ret;
+
+        INIT_LIST_HEAD(&edge->channels);
+        spin_lock_init(&edge->channels_lock);
+
+        INIT_WORK(&edge->scan_work, qcom_channel_scan_worker);
+        INIT_WORK(&edge->state_work, qcom_channel_state_worker);
+
+        edge->of_node = of_node_get(node);
+
+        key = "qcom,smd-edge";
+        ret = of_property_read_u32(node, key, &edge->edge_id);
+        if (ret) {
+                dev_err(dev, "edge missing %s property\n", key);
+                return -EINVAL;
+        }
+
+        edge->remote_pid = QCOM_SMEM_HOST_ANY;
+        key = "qcom,remote-pid";
+        of_property_read_u32(node, key, &edge->remote_pid);
+
+        syscon_np = of_parse_phandle(node, "qcom,ipc", 0);
+        if (!syscon_np) {
+                dev_err(dev, "no qcom,ipc node\n");
+                return -ENODEV;
+        }
+
+        edge->ipc_regmap = syscon_node_to_regmap(syscon_np);
+        if (IS_ERR(edge->ipc_regmap))
+                return PTR_ERR(edge->ipc_regmap);
+
+        key = "qcom,ipc";
+        ret = of_property_read_u32_index(node, key, 1, &edge->ipc_offset);
+        if (ret < 0) {
+                dev_err(dev, "no offset in %s\n", key);
+                return -EINVAL;
+        }
+
+        ret = of_property_read_u32_index(node, key, 2, &edge->ipc_bit);
+        if (ret < 0) {
+                dev_err(dev, "no bit in %s\n", key);
+                return -EINVAL;
+        }
+
+        irq = irq_of_parse_and_map(node, 0);
+        if (irq < 0) {
+                dev_err(dev, "required smd interrupt missing\n");
+                return -EINVAL;
+        }
+
+        ret = devm_request_irq(dev, irq,
+                               qcom_smd_edge_intr, IRQF_TRIGGER_RISING,
+                               node->name, edge);
+        if (ret) {
+                dev_err(dev, "failed to request smd irq\n");
+                return ret;
+        }
+
+        edge->irq = irq;
+
+        return 0;
+}
+
+/*
+ * Release function for an edge.
+  * Reset the state of each associated channel and free the edge context.
+ */
+static void qcom_smd_edge_release(struct device *dev)
+{
+        struct qcom_smd_channel *channel;
+        struct qcom_smd_edge *edge = to_smd_edge(dev);
+
+        list_for_each_entry(channel, &edge->channels, list) {
+                SET_RX_CHANNEL_INFO(channel, state, SMD_CHANNEL_CLOSED);
+                SET_RX_CHANNEL_INFO(channel, head, 0);
+                SET_RX_CHANNEL_INFO(channel, tail, 0);
+        }
+
+        kfree(edge);
+}
+
+/**
+ * qcom_smd_register_edge() - register an edge based on an device_node
+ * @parent:    parent device for the edge
+ * @node:      device_node describing the edge
+ *
+ * Returns an edge reference, or negative ERR_PTR() on failure.
+ */
+struct qcom_smd_edge *qcom_smd_register_edge(struct device *parent,
+                                             struct device_node *node)
+{
+        struct qcom_smd_edge *edge;
+        int ret;
+
+        edge = kzalloc(sizeof(*edge), GFP_KERNEL);
+        if (!edge)
+                return ERR_PTR(-ENOMEM);
+
+        init_waitqueue_head(&edge->new_channel_event);
+
+        edge->dev.parent = parent;
+        edge->dev.release = qcom_smd_edge_release;
+        dev_set_name(&edge->dev, "%s:%s", dev_name(parent), node->name);
+        ret = device_register(&edge->dev);
+        if (ret) {
+                pr_err("failed to register smd edge\n");
+                return ERR_PTR(ret);
+        }
+
+        ret = qcom_smd_parse_edge(&edge->dev, node, edge);
+        if (ret) {
+                dev_err(&edge->dev, "failed to parse smd edge\n");
+                goto unregister_dev;
+        }
+
+        schedule_work(&edge->scan_work);
+
+        return edge;
+
+unregister_dev:
+        put_device(&edge->dev);
+        return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(qcom_smd_register_edge);
+
+static int qcom_smd_remove_device(struct device *dev, void *data)
+{
+        device_unregister(dev);
+
+        return 0;
+}
+
+/**
+ * qcom_smd_unregister_edge() - release an edge and its children
+ * @edge:      edge reference acquired from qcom_smd_register_edge
+ */
+int qcom_smd_unregister_edge(struct qcom_smd_edge *edge)
+{
+        int ret;
+
+        disable_irq(edge->irq);
+        cancel_work_sync(&edge->scan_work);
+        cancel_work_sync(&edge->state_work);
+
+        ret = device_for_each_child(&edge->dev, NULL, qcom_smd_remove_device);
+        if (ret)
+                dev_warn(&edge->dev, "can't remove smd device: %d\n", ret);
+
+        device_unregister(&edge->dev);
+
+        return 0;
+}
+EXPORT_SYMBOL(qcom_smd_unregister_edge);
+
+static int qcom_smd_probe(struct platform_device *pdev)
+{
+        struct device_node *node;
+        void *p;
+
+        /* Wait for smem */
+        p = qcom_smem_get(QCOM_SMEM_HOST_ANY, smem_items[0].alloc_tbl_id, NULL);
+        if (PTR_ERR(p) == -EPROBE_DEFER)
+                return PTR_ERR(p);
+
+        for_each_available_child_of_node(pdev->dev.of_node, node)
+                qcom_smd_register_edge(&pdev->dev, node);
+
+        return 0;
+}
+
+static int qcom_smd_remove_edge(struct device *dev, void *data)
+{
+        struct qcom_smd_edge *edge = to_smd_edge(dev);
+
+        return qcom_smd_unregister_edge(edge);
+}
+
+/*
+ * Shut down all smd clients by making sure that each edge stops processing
+ * events and scanning for new channels, then call destroy on the devices.
+ */
+static int qcom_smd_remove(struct platform_device *pdev)
+{
+        int ret;
+
+        ret = device_for_each_child(&pdev->dev, NULL, qcom_smd_remove_edge);
+        if (ret)
+                dev_warn(&pdev->dev, "can't remove smd device: %d\n", ret);
+
+        return ret;
+}
+
+static const struct of_device_id qcom_smd_of_match[] = {
+        { .compatible = "qcom,smd" },
+        {}
+};
+MODULE_DEVICE_TABLE(of, qcom_smd_of_match);
+
+static struct platform_driver qcom_smd_driver = {
+        .probe = qcom_smd_probe,
+        .remove = qcom_smd_remove,
+        .driver = {
+                .name = "qcom-smd",
+                .of_match_table = qcom_smd_of_match,
+        },
+};
+
+static int __init qcom_smd_init(void)
+{
+        return platform_driver_register(&qcom_smd_driver);
+}
+subsys_initcall(qcom_smd_init);
+
+static void __exit qcom_smd_exit(void)
+{
+        platform_driver_unregister(&qcom_smd_driver);
+}
+module_exit(qcom_smd_exit);
+
+MODULE_AUTHOR("Bjorn Andersson <bjorn.andersson@sonymobile.com>");
+MODULE_DESCRIPTION("Qualcomm Shared Memory Driver");
+MODULE_LICENSE("GPL v2");