soc: qcom: Add Shared Memory Driver

This adds the Qualcomm Shared Memory Driver (SMD) providing
communication channels to remote processors, ontop of SMEM.
Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Andy Gross <agross@codeaurora.org>

drivers/soc/qcom/Kconfig

@@ -19,6 +19,14 @@ config QCOM_PM
 	  modes. It interface with various system drivers to put the cores in
 	  low power modes.
 
+config QCOM_SMD
+	tristate "Qualcomm Shared Memory Driver (SMD)"
+	depends on QCOM_SMEM
+	help
+	  Say y here to enable support for the Qualcomm Shared Memory Driver
+	  providing communication channels to remote processors in Qualcomm
+	  platforms.
+
 config QCOM_SMEM
 	tristate "Qualcomm Shared Memory Manager (SMEM)"
 	depends on ARCH_QCOM

drivers/soc/qcom/Makefile

 obj-$(CONFIG_QCOM_GSBI)	+=	qcom_gsbi.o
 obj-$(CONFIG_QCOM_PM)	+=	spm.o
+obj-$(CONFIG_QCOM_SMD) +=	smd.o
 obj-$(CONFIG_QCOM_SMEM) +=	smem.o

drivers/soc/qcom/smd.c

+/*
+ * 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/smd.h>
+#include <linux/soc/qcom/smem.h>
+#include <linux/wait.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_word;
+
+#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 = 14,
+		.info_base_id = 266,
+		.fifo_base_id = 202,
+	},
+};
+
+/**
+ * struct qcom_smd_edge - representing a remote processor
+ * @smd:		handle to qcom_smd
+ * @of_node:		of_node handle for information related to this edge
+ * @edge_id:		identifier of this edge
+ * @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
+ * @need_rescan:	flag that the @work needs to scan smem for new channels
+ * @smem_available:	last available amount of smem triggering a channel scan
+ * @work:		work item for edge house keeping
+ */
+struct qcom_smd_edge {
+	struct qcom_smd *smd;
+	struct device_node *of_node;
+	unsigned edge_id;
+
+	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);
+
+	bool need_rescan;
+	unsigned smem_available;
+
+	struct work_struct 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_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
+ * @tx_info:		byte aligned outgoing channel info
+ * @rx_info:		byte aligned incoming channel info
+ * @tx_info_word:	word aligned outgoing channel info
+ * @rx_info_word:	word aligned 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_device *qsdev;
+
+	char *name;
+	enum smd_channel_state state;
+	enum smd_channel_state remote_state;
+
+	struct smd_channel_info *tx_info;
+	struct smd_channel_info *rx_info;
+
+	struct smd_channel_info_word *tx_info_word;
+	struct smd_channel_info_word *rx_info_word;
+
+	struct mutex tx_lock;
+	wait_queue_head_t fblockread_event;
+
+	void *tx_fifo;
+	void *rx_fifo;
+	int fifo_size;
+
+	void *bounce_buffer;
+	int (*cb)(struct qcom_smd_device *, const void *, size_t);
+
+	spinlock_t recv_lock;
+
+	int pkt_size;
+
+	struct list_head list;
+};
+
+/**
+ * struct qcom_smd - smd struct
+ * @dev:	device struct
+ * @num_edges:	number of entries in @edges
+ * @edges:	array of edges to be handled
+ */
+struct qcom_smd {
+	struct device *dev;
+
+	unsigned num_edges;
+	struct qcom_smd_edge edges[0];
+};
+
+/*
+ * Format of the smd_info smem items, for byte aligned channels.
+ */
+struct smd_channel_info {
+	u32 state;
+	u8  fDSR;
+	u8  fCTS;
+	u8  fCD;
+	u8  fRI;
+	u8  fHEAD;
+	u8  fTAIL;
+	u8  fSTATE;
+	u8  fBLOCKREADINTR;
+	u32 tail;
+	u32 head;
+};
+
+/*
+ * Format of the smd_info smem items, for word aligned channels.
+ */
+struct smd_channel_info_word {
+	u32 state;
+	u32 fDSR;
+	u32 fCTS;
+	u32 fCD;
+	u32 fRI;
+	u32 fHEAD;
+	u32 fTAIL;
+	u32 fSTATE;
+	u32 fBLOCKREADINTR;
+	u32 tail;
+	u32 head;
+};
+
+#define GET_RX_CHANNEL_INFO(channel, param) \
+	(channel->rx_info_word ? \
+		channel->rx_info_word->param : \
+		channel->rx_info->param)
+
+#define SET_RX_CHANNEL_INFO(channel, param, value) \
+	(channel->rx_info_word ? \
+		(channel->rx_info_word->param = value) : \
+		(channel->rx_info->param = value))
+
+#define GET_TX_CHANNEL_INFO(channel, param) \
+	(channel->tx_info_word ? \
+		channel->tx_info_word->param : \
+		channel->tx_info->param)
+
+#define SET_TX_CHANNEL_INFO(channel, param, value) \
+	(channel->tx_info_word ? \
+		(channel->tx_info_word->param = value) : \
+		(channel->tx_info->param = 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];
+	u32 cid;
+	u32 flags;
+	u32 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_INFO(channel, fDSR, 0);
+	SET_TX_CHANNEL_INFO(channel, fCTS, 0);
+	SET_TX_CHANNEL_INFO(channel, fCD, 0);
+	SET_TX_CHANNEL_INFO(channel, fRI, 0);
+	SET_TX_CHANNEL_INFO(channel, fHEAD, 0);
+	SET_TX_CHANNEL_INFO(channel, fTAIL, 0);
+	SET_TX_CHANNEL_INFO(channel, fSTATE, 1);
+	SET_TX_CHANNEL_INFO(channel, fBLOCKREADINTR, 0);
+	SET_TX_CHANNEL_INFO(channel, head, 0);
+	SET_TX_CHANNEL_INFO(channel, tail, 0);
+
+	qcom_smd_signal_channel(channel);
+
+	channel->state = SMD_CHANNEL_CLOSED;
+	channel->pkt_size = 0;
+}
+
+/*
+ * 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->smd->dev, "set_state(%s, %d)\n", channel->name, state);
+
+	SET_TX_CHANNEL_INFO(channel, fDSR, is_open);
+	SET_TX_CHANNEL_INFO(channel, fCTS, is_open);
+	SET_TX_CHANNEL_INFO(channel, fCD, is_open);
+
+	SET_TX_CHANNEL_INFO(channel, state, state);
+	SET_TX_CHANNEL_INFO(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)
+{
+	u32 *dst = (u32 *)_dst;
+	u32 *src = (u32 *)_src;
+
+	if (word_aligned) {
+		count /= sizeof(u32);
+		while (count--)
+			writel_relaxed(*src++, dst++);
+	} 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)
+{
+	u32 *dst = (u32 *)_dst;
+	u32 *src = (u32 *)_src;
+
+	if (word_aligned) {
+		count /= sizeof(u32);
+		while (count--)
+			*dst++ = readl_relaxed(src++);
+	} 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->rx_info_word != NULL;
+	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 qcom_smd_device *qsdev = channel->qsdev;
+	unsigned tail;
+	size_t len;
+	void *ptr;
+	int ret;
+
+	if (!channel->cb)
+		return 0;
+
+	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 = channel->cb(qsdev, ptr, len);
+	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;
+	u32 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_INFO(channel, fSTATE, 0);
+
+	/* Signal waiting qcom_smd_send() about the interrupt */
+	if (!GET_TX_CHANNEL_INFO(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_INFO(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 = 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_INFO(channel, fTAIL, 1);
+
+	/* Signal the remote that we've consumed the data (if requested) */
+	if (!GET_RX_CHANNEL_INFO(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_worker = 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_worker |= 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->edge_id);
+	if (available != edge->smem_available) {
+		edge->smem_available = available;
+		edge->need_rescan = true;
+		kick_worker = true;
+	}
+
+	if (kick_worker)
+		schedule_work(&edge->work);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Delivers any outstanding packets in the rx fifo, can be used after probe of
+ * the clients to deliver any packets that wasn't delivered before the client
+ * was setup.
+ */
+static void qcom_smd_channel_resume(struct qcom_smd_channel *channel)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&channel->recv_lock, flags);
+	qcom_smd_channel_intr(channel);
+	spin_unlock_irqrestore(&channel->recv_lock, flags);
+}
+
+/*
+ * 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->tx_info_word != NULL;
+	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.
+ */
+int qcom_smd_send(struct qcom_smd_channel *channel, const void *data, int len)
+{
+	u32 hdr[5] = {len,};
+	int tlen = sizeof(hdr) + len;
+	int ret;
+
+	/* Word aligned channels only accept word size aligned data */
+	if (channel->rx_info_word != NULL && len % 4)
+		return -EINVAL;
+
+	ret = mutex_lock_interruptible(&channel->tx_lock);
+	if (ret)
+		return ret;
+
+	while (qcom_smd_get_tx_avail(channel) < tlen) {
+		if (channel->state != SMD_CHANNEL_OPENED) {
+			ret = -EPIPE;
+			goto out;
+		}
+
+		SET_TX_CHANNEL_INFO(channel, fBLOCKREADINTR, 1);
+
+		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_INFO(channel, fBLOCKREADINTR, 0);
+	}
+
+	SET_TX_CHANNEL_INFO(channel, fTAIL, 0);
+
+	qcom_smd_write_fifo(channel, hdr, sizeof(hdr));
+	qcom_smd_write_fifo(channel, data, len);
+
+	SET_TX_CHANNEL_INFO(channel, fHEAD, 1);
+
+	/* Ensure ordering of channel info updates */
+	wmb();
+
+	qcom_smd_signal_channel(channel);
+
+out:
+	mutex_unlock(&channel->tx_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(qcom_smd_send);
+
+static struct qcom_smd_device *to_smd_device(struct device *dev)
+{
+	return container_of(dev, struct qcom_smd_device, dev);
+}
+
+static struct qcom_smd_driver *to_smd_driver(struct device *dev)
+{
+	struct qcom_smd_device *qsdev = to_smd_device(dev);
+
+	return container_of(qsdev->dev.driver, struct qcom_smd_driver, driver);
+}
+
+static int qcom_smd_dev_match(struct device *dev, struct device_driver *drv)
+{
+	return of_driver_match_device(dev, drv);
+}
+
+/*
+ * Probe the smd client.
+ *
+ * The remote side have indicated that it want the channel to be opened, so
+ * complete the state handshake and probe our client driver.
+ */
+static int qcom_smd_dev_probe(struct device *dev)
+{
+	struct qcom_smd_device *qsdev = to_smd_device(dev);
+	struct qcom_smd_driver *qsdrv = to_smd_driver(dev);
+	struct qcom_smd_channel *channel = qsdev->channel;
+	size_t bb_size;
+	int ret;
+
+	/*
+	 * 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;
+
+	channel->cb = qsdrv->callback;
+
+	qcom_smd_channel_set_state(channel, SMD_CHANNEL_OPENING);
+
+	qcom_smd_channel_set_state(channel, SMD_CHANNEL_OPENED);
+
+	ret = qsdrv->probe(qsdev);
+	if (ret)
+		goto err;
+
+	qcom_smd_channel_resume(channel);
+
+	return 0;
+
+err:
+	dev_err(&qsdev->dev, "probe failed\n");
+
+	channel->cb = NULL;
+	kfree(channel->bounce_buffer);
+	channel->bounce_buffer = NULL;
+
+	qcom_smd_channel_set_state(channel, SMD_CHANNEL_CLOSED);
+	return ret;
+}
+
+/*
+ * Remove the smd client.
+ *
+ * The channel is going away, for some reason, so remove the smd client and
+ * reset the channel state.
+ */
+static int qcom_smd_dev_remove(struct device *dev)
+{
+	struct qcom_smd_device *qsdev = to_smd_device(dev);
+	struct qcom_smd_driver *qsdrv = to_smd_driver(dev);
+	struct qcom_smd_channel *channel = qsdev->channel;
+	unsigned long flags;
+
+	qcom_smd_channel_set_state(channel, SMD_CHANNEL_CLOSING);
+
+	/*
+	 * Make sure we don't race with the code receiving data.
+	 */
+	spin_lock_irqsave(&channel->recv_lock, flags);
+	channel->cb = NULL;
+	spin_unlock_irqrestore(&channel->recv_lock, flags);
+
+	/* Wake up any sleepers in qcom_smd_send() */
+	wake_up_interruptible(&channel->fblockread_event);
+
+	/*
+	 * We expect that the client might block in remove() waiting for any
+	 * outstanding calls to qcom_smd_send() to wake up and finish.
+	 */
+	if (qsdrv->remove)
+		qsdrv->remove(qsdev);
+
+	/*
+	 * The client is now gone, cleanup and reset the channel state.
+	 */
+	channel->qsdev = NULL;
+	kfree(channel->bounce_buffer);
+	channel->bounce_buffer = NULL;
+
+	qcom_smd_channel_set_state(channel, SMD_CHANNEL_CLOSED);
+
+	qcom_smd_channel_reset(channel);
+
+	return 0;
+}
+
+static struct bus_type qcom_smd_bus = {
+	.name = "qcom_smd",
+	.match = qcom_smd_dev_match,
+	.probe = qcom_smd_dev_probe,
+	.remove = qcom_smd_dev_remove,
+};
+
+/*
+ * Release function for the qcom_smd_device object.
+ */
+static void qcom_smd_release_device(struct device *dev)
+{
+	struct qcom_smd_device *qsdev = to_smd_device(dev);
+
+	kfree(qsdev);
+}
+
+/*
+ * 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) {
+			of_node_put(child);
+			continue;
+		}
+
+		if (strcmp(name, channel) == 0)
+			return child;
+	}
+
+	return NULL;
+}
+
+/*
+ * 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 qcom_smd_edge *edge = channel->edge;
+	struct device_node *node;
+	struct qcom_smd *smd = edge->smd;
+	int ret;
+
+	if (channel->qsdev)
+		return -EEXIST;
+
+	node = qcom_smd_match_channel(edge->of_node, channel->name);
+	if (!node) {
+		dev_dbg(smd->dev, "no match for '%s'\n", channel->name);
+		return -ENXIO;
+	}
+
+	dev_dbg(smd->dev, "registering '%s'\n", channel->name);
+
+	qsdev = kzalloc(sizeof(*qsdev), GFP_KERNEL);
+	if (!qsdev)
+		return -ENOMEM;
+
+	dev_set_name(&qsdev->dev, "%s.%s", edge->of_node->name, node->name);
+	qsdev->dev.parent = smd->dev;
+	qsdev->dev.bus = &qcom_smd_bus;
+	qsdev->dev.release = qcom_smd_release_device;
+	qsdev->dev.of_node = node;
+
+	qsdev->channel = channel;
+
+	channel->qsdev = qsdev;
+
+	ret = device_register(&qsdev->dev);
+	if (ret) {
+		dev_err(smd->dev, "device_register failed: %d\n", ret);
+		put_device(&qsdev->dev);
+	}
+
+	return ret;
+}
+
+/*
+ * Destroy a smd client device for a channel that's going away.
+ */
+static void qcom_smd_destroy_device(struct qcom_smd_channel *channel)
+{
+	struct device *dev;
+
+	BUG_ON(!channel->qsdev);
+
+	dev = &channel->qsdev->dev;
+
+	device_unregister(dev);
+	of_node_put(dev->of_node);
+	put_device(dev);
+}
+
+/**
+ * qcom_smd_driver_register - register a smd driver
+ * @qsdrv:	qcom_smd_driver struct
+ */
+int qcom_smd_driver_register(struct qcom_smd_driver *qsdrv)
+{
+	qsdrv->driver.bus = &qcom_smd_bus;
+	return driver_register(&qsdrv->driver);
+}
+EXPORT_SYMBOL(qcom_smd_driver_register);
+
+/**
+ * qcom_smd_driver_unregister - unregister a smd driver
+ * @qsdrv:	qcom_smd_driver struct
+ */
+void qcom_smd_driver_unregister(struct qcom_smd_driver *qsdrv)
+{
+	driver_unregister(&qsdrv->driver);
+}
+EXPORT_SYMBOL(qcom_smd_driver_unregister);
+
+/*
+ * 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;
+	struct qcom_smd *smd = edge->smd;
+	size_t fifo_size;
+	size_t info_size;
+	void *fifo_base;
+	void *info;
+	int ret;
+
+	channel = devm_kzalloc(smd->dev, sizeof(*channel), GFP_KERNEL);
+	if (!channel)
+		return ERR_PTR(-ENOMEM);
+
+	channel->edge = edge;
+	channel->name = devm_kstrdup(smd->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);
+
+	ret = qcom_smem_get(edge->edge_id, smem_info_item, (void **)&info, &info_size);
+	if (ret)
+		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->tx_info_word = info;
+		channel->rx_info_word = info + sizeof(struct smd_channel_info_word);
+	} else if (info_size == 2 * sizeof(struct smd_channel_info)) {
+		channel->tx_info = info;
+		channel->rx_info = info + sizeof(struct smd_channel_info);
+	} else {
+		dev_err(smd->dev,
+			"channel info of size %zu not supported\n", info_size);
+		ret = -EINVAL;
+		goto free_name_and_channel;
+	}
+
+	ret = qcom_smem_get(edge->edge_id, smem_fifo_item, &fifo_base, &fifo_size);
+	if (ret)
+		goto free_name_and_channel;
+
+	/* The channel consist of a rx and tx fifo of equal size */
+	fifo_size /= 2;
+
+	dev_dbg(smd->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(smd->dev, channel->name);
+	devm_kfree(smd->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_discover_channels(struct qcom_smd_edge *edge)
+{
+	struct qcom_smd_alloc_entry *alloc_tbl;
+	struct qcom_smd_alloc_entry *entry;
+	struct qcom_smd_channel *channel;
+	struct qcom_smd *smd = edge->smd;
+	unsigned long flags;
+	unsigned fifo_id;
+	unsigned info_id;
+	int ret;
+	int tbl;
+	int i;
+
+	for (tbl = 0; tbl < SMD_ALLOC_TBL_COUNT; tbl++) {
+		ret = qcom_smem_get(edge->edge_id,
+				    smem_items[tbl].alloc_tbl_id,
+				    (void **)&alloc_tbl,
+				    NULL);
+		if (ret < 0)
+			continue;
+
+		for (i = 0; i < SMD_ALLOC_TBL_SIZE; i++) {
+			entry = &alloc_tbl[i];
+			if (test_bit(i, edge->allocated[tbl]))
+				continue;
+
+			if (entry->ref_count == 0)
+				continue;
+
+			if (!entry->name[0])
+				continue;
+
+			if (!(entry->flags & SMD_CHANNEL_FLAGS_PACKET))
+				continue;
+
+			if ((entry->flags & SMD_CHANNEL_FLAGS_EDGE_MASK) != edge->edge_id)
+				continue;
+
+			info_id = smem_items[tbl].info_base_id + entry->cid;
+			fifo_id = smem_items[tbl].fifo_base_id + entry->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(smd->dev, "new channel found: '%s'\n", channel->name);
+			set_bit(i, edge->allocated[tbl]);
+		}
+	}
+
+	schedule_work(&edge->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 is not needed to be held during the traversal
+ * of the channels list as it's done synchronously with the only writer.
+ */
+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,
+						  work);
+	unsigned remote_state;
+
+	/*
+	 * Rescan smem if we have reason to belive that there are new channels.
+	 */
+	if (edge->need_rescan) {
+		edge->need_rescan = false;
+		qcom_discover_channels(edge);
+	}
+
+	/*
+	 * Register a device for any closed channel where the remote processor
+	 * is showing interest in opening the channel.
+	 */
+	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;
+
+		qcom_smd_create_device(channel);
+	}
+
+	/*
+	 * 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;
+
+		qcom_smd_destroy_device(channel);
+	}
+}
+
+/*
+ * 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->work, qcom_channel_state_worker);
+
+	edge->of_node = of_node_get(node);
+
+	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;
+
+	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;
+	}
+
+	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;
+	}
+
+	return 0;
+}
+
+static int qcom_smd_probe(struct platform_device *pdev)
+{
+	struct qcom_smd_edge *edge;
+	struct device_node *node;
+	struct qcom_smd *smd;
+	size_t array_size;
+	int num_edges;
+	int ret;
+	int i = 0;
+
+	/* Wait for smem */
+	ret = qcom_smem_get(QCOM_SMEM_HOST_ANY, smem_items[0].alloc_tbl_id, NULL, NULL);
+	if (ret == -EPROBE_DEFER)
+		return ret;
+
+	num_edges = of_get_available_child_count(pdev->dev.of_node);
+	array_size = sizeof(*smd) + num_edges * sizeof(struct qcom_smd_edge);
+	smd = devm_kzalloc(&pdev->dev, array_size, GFP_KERNEL);
+	if (!smd)
+		return -ENOMEM;
+	smd->dev = &pdev->dev;
+
+	smd->num_edges = num_edges;
+	for_each_available_child_of_node(pdev->dev.of_node, node) {
+		edge = &smd->edges[i++];
+		edge->smd = smd;
+
+		ret = qcom_smd_parse_edge(&pdev->dev, node, edge);
+		if (ret)
+			continue;
+
+		edge->need_rescan = true;
+		schedule_work(&edge->work);
+	}
+
+	platform_set_drvdata(pdev, smd);
+
+	return 0;
+}
+
+/*
+ * 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)
+{
+	struct qcom_smd_channel *channel;
+	struct qcom_smd_edge *edge;
+	struct qcom_smd *smd = platform_get_drvdata(pdev);
+	int i;
+
+	for (i = 0; i < smd->num_edges; i++) {
+		edge = &smd->edges[i];
+
+		disable_irq(edge->irq);
+		cancel_work_sync(&edge->work);
+
+		list_for_each_entry(channel, &edge->channels, list) {
+			if (!channel->qsdev)
+				continue;
+
+			qcom_smd_destroy_device(channel);
+		}
+	}
+
+	return 0;
+}
+
+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)
+{
+	int ret;
+
+	ret = bus_register(&qcom_smd_bus);
+	if (ret) {
+		pr_err("failed to register smd bus: %d\n", ret);
+		return ret;
+	}
+
+	return platform_driver_register(&qcom_smd_driver);
+}
+postcore_initcall(qcom_smd_init);
+
+static void __exit qcom_smd_exit(void)
+{
+	platform_driver_unregister(&qcom_smd_driver);
+	bus_unregister(&qcom_smd_bus);
+}
+module_exit(qcom_smd_exit);
+
+MODULE_AUTHOR("Bjorn Andersson <bjorn.andersson@sonymobile.com>");
+MODULE_DESCRIPTION("Qualcomm Shared Memory Driver");
+MODULE_LICENSE("GPL v2");

include/linux/soc/qcom/smd.h

+#ifndef __QCOM_SMD_H__
+#define __QCOM_SMD_H__
+
+#include <linux/device.h>
+#include <linux/mod_devicetable.h>
+
+struct qcom_smd;
+struct qcom_smd_channel;
+struct qcom_smd_lookup;
+
+/**
+ * struct qcom_smd_device - smd device struct
+ * @dev:	the device struct
+ * @channel:	handle to the smd channel for this device
+ */
+struct qcom_smd_device {
+	struct device dev;
+	struct qcom_smd_channel *channel;
+};
+
+/**
+ * struct qcom_smd_driver - smd driver struct
+ * @driver:	underlying device driver
+ * @probe:	invoked when the smd channel is found
+ * @remove:	invoked when the smd channel is closed
+ * @callback:	invoked when an inbound message is received on the channel,
+ *		should return 0 on success or -EBUSY if the data cannot be
+ *		consumed at this time
+ */
+struct qcom_smd_driver {
+	struct device_driver driver;
+	int (*probe)(struct qcom_smd_device *dev);
+	void (*remove)(struct qcom_smd_device *dev);
+	int (*callback)(struct qcom_smd_device *, const void *, size_t);
+};
+
+int qcom_smd_driver_register(struct qcom_smd_driver *drv);
+void qcom_smd_driver_unregister(struct qcom_smd_driver *drv);
+
+#define module_qcom_smd_driver(__smd_driver) \
+	module_driver(__smd_driver, qcom_smd_driver_register, \
+		      qcom_smd_driver_unregister)
+
+int qcom_smd_send(struct qcom_smd_channel *channel, const void *data, int len);
+
+#endif