drivers/char/rdbg.c

/*
 * Copyright (c) 2013-2015, 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/cdev.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <soc/qcom/smsm.h>
#include <linux/uaccess.h>
#include <linux/interrupt.h>

#define SMP2P_NUM_PROCS				8
#define MAX_RETRIES				20

#define SM_VERSION				1
#define SM_BLOCKSIZE				128

#define SMQ_MAGIC_INIT				0xFF00FF00
#define SMQ_MAGIC_PRODUCER			(SMQ_MAGIC_INIT | 0x1)
#define SMQ_MAGIC_CONSUMER			(SMQ_MAGIC_INIT | 0x2)

enum SMQ_STATUS {
	SMQ_SUCCESS    =  0,
	SMQ_ENOMEMORY  = -1,
	SMQ_EBADPARM   = -2,
	SMQ_UNDERFLOW  = -3,
	SMQ_OVERFLOW   = -4
};

enum smq_type {
	PRODUCER = 1,
	CONSUMER = 2,
	INVALID  = 3
};

struct smq_block_map {
	uint32_t index_read;
	uint32_t num_blocks;
	uint8_t *map;
};

struct smq_node {
	uint16_t index_block;
	uint16_t num_blocks;
} __attribute__ ((__packed__));

struct smq_hdr {
	uint8_t producer_version;
	uint8_t consumer_version;
} __attribute__ ((__packed__));

struct smq_out_state {
	uint32_t init;
	uint32_t index_check_queue_for_reset;
	uint32_t index_sent_write;
	uint32_t index_free_read;
} __attribute__ ((__packed__));

struct smq_out {
	struct smq_out_state s;
	struct smq_node sent[1];
};

struct smq_in_state {
	uint32_t init;
	uint32_t index_check_queue_for_reset_ack;
	uint32_t index_sent_read;
	uint32_t index_free_write;
} __attribute__ ((__packed__));

struct smq_in {
	struct smq_in_state s;
	struct smq_node free[1];
};

struct smq {
	struct smq_hdr *hdr;
	struct smq_out *out;
	struct smq_in *in;
	uint8_t *blocks;
	uint32_t num_blocks;
	struct mutex *lock;
	uint32_t initialized;
	struct smq_block_map block_map;
	enum smq_type type;
};

struct gpio_info {
	int gpio_base_id;
	int irq_base_id;
};

struct rdbg_data {
	struct device *device;
	struct completion work;
	struct gpio_info in;
	struct gpio_info out;
	bool   device_initialized;
	int    gpio_out_offset;
	bool   device_opened;
	void   *smem_addr;
	size_t smem_size;
	struct smq    producer_smrb;
	struct smq    consumer_smrb;
	struct mutex  write_mutex;
};

struct rdbg_device {
	struct cdev cdev;
	struct class *class;
	dev_t dev_no;
	int num_devices;
	struct rdbg_data *rdbg_data;
};

static struct rdbg_device g_rdbg_instance = {
	{ {0} },
	NULL,
	0,
	SMP2P_NUM_PROCS,
	NULL
};

struct processor_specific_info {
	char *name;
	unsigned int smem_buffer_addr;
	size_t smem_buffer_size;
};

static struct processor_specific_info proc_info[SMP2P_NUM_PROCS] = {
		{0},	/*APPS*/
		{"rdbg_modem", 0, 0},	/*MODEM*/
		{"rdbg_adsp", SMEM_LC_DEBUGGER, 16*1024},	/*ADSP*/
		{0},	/*SMP2P_RESERVED_PROC_1*/
		{"rdbg_wcnss", 0, 0},		/*WCNSS*/
		{0},	/*SMP2P_RESERVED_PROC_2*/
		{0},	/*SMP2P_POWER_PROC*/
		{0}		/*SMP2P_REMOTE_MOCK_PROC*/
};

static int smq_blockmap_get(struct smq_block_map *block_map,
	uint32_t *block_index, uint32_t n)
{
	uint32_t start;
	uint32_t mark = 0;
	uint32_t found = 0;
	uint32_t i = 0;

	start = block_map->index_read;

	if (n == 1) {
		do {
			if (!block_map->map[block_map->index_read]) {
				*block_index = block_map->index_read;
				block_map->map[block_map->index_read] = 1;
				block_map->index_read++;
				block_map->index_read %= block_map->num_blocks;
				return SMQ_SUCCESS;
			}
			block_map->index_read++;
		} while (start != (block_map->index_read %=
			block_map->num_blocks));
	} else {
		mark = block_map->num_blocks;

		do {
			if (!block_map->map[block_map->index_read]) {
				if (mark > block_map->index_read) {
					mark = block_map->index_read;
					start = block_map->index_read;
					found = 0;
				}

				found++;
				if (found == n) {
					*block_index = mark;
					for (i = 0; i < n; i++)
						block_map->map[mark + i] =
							(uint8_t)(n - i);
					block_map->index_read += block_map->map
						[block_map->index_read] - 1;
					return SMQ_SUCCESS;
				}
			} else {
				found = 0;
				block_map->index_read += block_map->map
					[block_map->index_read] - 1;
				mark = block_map->num_blocks;
			}
			block_map->index_read++;
		} while (start != (block_map->index_read %=
			block_map->num_blocks));
	}

	return SMQ_ENOMEMORY;
}

static void smq_blockmap_put(struct smq_block_map *block_map, uint32_t i)
{
	uint32_t num_blocks = block_map->map[i];

	while (num_blocks--) {
		block_map->map[i] = 0;
		i++;
	}
}

static int smq_blockmap_reset(struct smq_block_map *block_map)
{
	if (!block_map->map)
		return SMQ_ENOMEMORY;
	memset(block_map->map, 0 , block_map->num_blocks + 1);
	block_map->index_read = 0;

	return SMQ_SUCCESS;
}

static int smq_blockmap_ctor(struct smq_block_map *block_map,
	uint32_t num_blocks)
{
	if (num_blocks <= 1)
		return SMQ_ENOMEMORY;

	block_map->map = kcalloc(num_blocks, sizeof(uint8_t), GFP_KERNEL);
	if (!block_map->map)
		return SMQ_ENOMEMORY;

	block_map->num_blocks = num_blocks - 1;
	smq_blockmap_reset(block_map);

	return SMQ_SUCCESS;
}

static void smq_blockmap_dtor(struct smq_block_map *block_map)
{
	kfree(block_map->map);
	block_map->map = NULL;
}

static int smq_free(struct smq *smq, void *data)
{
	struct smq_node node;
	uint32_t index_block;
	int err = SMQ_SUCCESS;

	if (smq->lock)
		mutex_lock(smq->lock);

	if ((SM_VERSION != smq->hdr->producer_version) &&
		(SMQ_MAGIC_PRODUCER != smq->out->s.init)) {
		err = SMQ_UNDERFLOW;
		goto bail;
	}

	index_block = ((uint8_t *)data - smq->blocks) / SM_BLOCKSIZE;
	if (index_block >= smq->num_blocks) {
		err = SMQ_EBADPARM;
		goto bail;
	}

	node.index_block = (uint16_t)index_block;
	node.num_blocks = 0;
	*((struct smq_node *)(smq->in->free + smq->in->
		s.index_free_write)) = node;

	smq->in->s.index_free_write = (smq->in->s.index_free_write + 1)
		% smq->num_blocks;

bail:
	if (smq->lock)
		mutex_unlock(smq->lock);
	return err;
}

static int smq_receive(struct smq *smq, void **pp, int *pnsize, int *pbmore)
{
	struct smq_node *node;
	int err = SMQ_SUCCESS;
	int more = 0;

	if ((SM_VERSION != smq->hdr->producer_version) &&
		(SMQ_MAGIC_PRODUCER != smq->out->s.init))
		return SMQ_UNDERFLOW;

	if (smq->in->s.index_sent_read == smq->out->s.index_sent_write) {
		err = SMQ_UNDERFLOW;
		goto bail;
	}

	node = (struct smq_node *)(smq->out->sent + smq->in->s.index_sent_read);
	if (node->index_block >= smq->num_blocks) {
		err = SMQ_EBADPARM;
		goto bail;
	}

	smq->in->s.index_sent_read = (smq->in->s.index_sent_read + 1)
		% smq->num_blocks;

	*pp = smq->blocks + (node->index_block * SM_BLOCKSIZE);
	*pnsize = SM_BLOCKSIZE * node->num_blocks;

	/* Ensure that the reads and writes are updated in the memory
	when they are done and not cached. Also, ensure that the reads
	and writes are not reordered as they are shared between two cores. */
	rmb();
	if (smq->in->s.index_sent_read != smq->out->s.index_sent_write)
		more = 1;

bail:
	*pbmore = more;
	return err;
}

static int smq_alloc_send(struct smq *smq, const uint8_t *pcb, int nsize)
{
	void *pv = 0;
	int num_blocks;
	uint32_t index_block = 0;
	int err = SMQ_SUCCESS;
	struct smq_node *node = NULL;

	mutex_lock(smq->lock);

	if ((SMQ_MAGIC_CONSUMER == smq->in->s.init) &&
	 (SM_VERSION == smq->hdr->consumer_version)) {
		if (smq->out->s.index_check_queue_for_reset ==
			smq->in->s.index_check_queue_for_reset_ack) {
			while (smq->out->s.index_free_read !=
				smq->in->s.index_free_write) {
				node = (struct smq_node *)(
					smq->in->free +
					smq->out->s.index_free_read);
				if (node->index_block >= smq->num_blocks) {
					err = SMQ_EBADPARM;
					goto bail;
				}

				smq->out->s.index_free_read =
					(smq->out->s.index_free_read + 1)
						% smq->num_blocks;

				smq_blockmap_put(&smq->block_map,
					node->index_block);
				/* Ensure that the reads and writes are
				updated	in the memory when they are done
				and not cached. Also, ensure that the reads
				and writes are not reordered as they are
				shared between two cores. */
				rmb();
			}
		}
	}

	num_blocks = ALIGN(nsize, SM_BLOCKSIZE)/SM_BLOCKSIZE;
	err = smq_blockmap_get(&smq->block_map, &index_block, num_blocks);
	if (SMQ_SUCCESS != err)
		goto bail;

	pv = smq->blocks + (SM_BLOCKSIZE * index_block);

	err = copy_from_user((void *)pv, (void *)pcb, nsize);
	if (0 != err)
		goto bail;

	((struct smq_node *)(smq->out->sent +
		smq->out->s.index_sent_write))->index_block
			= (uint16_t)index_block;
	((struct smq_node *)(smq->out->sent +
		smq->out->s.index_sent_write))->num_blocks
			= (uint16_t)num_blocks;

	smq->out->s.index_sent_write = (smq->out->s.index_sent_write + 1)
		% smq->num_blocks;

bail:
	if (SMQ_SUCCESS != err) {
		if (pv)
			smq_blockmap_put(&smq->block_map, index_block);
	}
	mutex_unlock(smq->lock);
	return err;
}

static int smq_reset_producer_queue_internal(struct smq *smq,
	uint32_t reset_num)
{
	int retval = 0;
	uint32_t i;

	if (PRODUCER != smq->type)
		goto bail;

	mutex_lock(smq->lock);
	if (smq->out->s.index_check_queue_for_reset != reset_num) {
		smq->out->s.index_check_queue_for_reset = reset_num;
		for (i = 0; i < smq->num_blocks; i++)
			(smq->out->sent + i)->index_block = 0xFFFF;

		smq_blockmap_reset(&smq->block_map);
		smq->out->s.index_sent_write = 0;
		smq->out->s.index_free_read = 0;
		retval = 1;
	}
	mutex_unlock(smq->lock);

bail:
	return retval;
}

static int smq_check_queue_reset(struct smq *p_cons, struct smq *p_prod)
{
	int retval = 0;
	uint32_t reset_num, i;

	if ((CONSUMER != p_cons->type) ||
		(SMQ_MAGIC_PRODUCER != p_cons->out->s.init) ||
		(SM_VERSION != p_cons->hdr->producer_version))
		goto bail;

	reset_num = p_cons->out->s.index_check_queue_for_reset;
	if (p_cons->in->s.index_check_queue_for_reset_ack != reset_num) {
		p_cons->in->s.index_check_queue_for_reset_ack = reset_num;
		for (i = 0; i < p_cons->num_blocks; i++)
			(p_cons->in->free + i)->index_block = 0xFFFF;

		p_cons->in->s.index_sent_read = 0;
		p_cons->in->s.index_free_write = 0;

		retval = smq_reset_producer_queue_internal(p_prod, reset_num);
	}

bail:
	return retval;
}

static int check_subsystem_debug_enabled(void *base_addr, int size)
{
	int num_blocks;
	uint8_t *pb_orig;
	uint8_t *pb;
	struct smq smq;
	int err = 0;

	pb = pb_orig = (uint8_t *)base_addr;
	pb += sizeof(struct smq_hdr);
	pb = PTR_ALIGN(pb, 8);
	size -= pb - (uint8_t *)pb_orig;
	num_blocks = (int)((size - sizeof(struct smq_out_state) -
		sizeof(struct smq_in_state))/(SM_BLOCKSIZE +
		sizeof(struct smq_node) * 2));
	if (0 >= num_blocks) {
		err = SMQ_EBADPARM;
		goto bail;
	}

	pb += num_blocks * SM_BLOCKSIZE;
	smq.out = (struct smq_out *)pb;
	pb += sizeof(struct smq_out_state) + (num_blocks *
		sizeof(struct smq_node));
	smq.in = (struct smq_in *)pb;

	if (SMQ_MAGIC_CONSUMER != smq.in->s.init) {
		pr_err("%s, smq in consumer not initialized", __func__);
		err = -ECOMM;
	}

bail:
	return err;
}

static void smq_dtor(struct smq *smq)
{
	if (SMQ_MAGIC_INIT == smq->initialized) {
		switch (smq->type) {
		case PRODUCER:
			smq->out->s.init = 0;
			smq_blockmap_dtor(&smq->block_map);
			break;
		case CONSUMER:
			smq->in->s.init = 0;
			break;
		default:
		case INVALID:
			break;
		}

		smq->initialized = 0;
	}
}

/*
 * The shared memory is used as a circular ring buffer in each direction.
 * Thus we have a bi-directional shared memory channel between the AP
 * and a subsystem. We call this SMQ. Each memory channel contains a header,
 * data and a control mechanism that is used to synchronize read and write
 * of data between the AP and the remote subsystem.
 *
 * Overall SMQ memory view:
 *
 *    +------------------------------------------------+
 *    | SMEM buffer                                    |
 *    |-----------------------+------------------------|
 *    |Producer: LA           | Producer: Remote       |
 *    |Consumer: Remote       |           subsystem    |
 *    |          subsystem    | Consumer: LA           |
 *    |                       |                        |
 *    |               Producer|                Consumer|
 *    +-----------------------+------------------------+
 *    |                       |
 *    |                       |
 *    |                       +--------------------------------------+
 *    |                                                              |
 *    |                                                              |
 *    v                                                              v
 *    +--------------------------------------------------------------+
 *    |   Header  |       Data      |            Control             |
 *    +-----------+---+---+---+-----+----+--+--+-----+---+--+--+-----+
 *    |           | b | b | b |     | S  |n |n |     | S |n |n |     |
 *    |  Producer | l | l | l |     | M  |o |o |     | M |o |o |     |
 *    |    Ver    | o | o | o |     | Q  |d |d |     | Q |d |d |     |
 *    |-----------| c | c | c | ... |    |e |e | ... |   |e |e | ... |
 *    |           | k | k | k |     | O  |  |  |     | I |  |  |     |
 *    |  Consumer |   |   |   |     | u  |0 |1 |     | n |0 |1 |     |
 *    |    Ver    | 0 | 1 | 2 |     | t  |  |  |     |   |  |  |     |
 *    +-----------+---+---+---+-----+----+--+--+-----+---+--+--+-----+
 *                                       |           |
 *                                       +           |
 *                                                   |
 *                          +------------------------+
 *                          |
 *                          v
 *                        +----+----+----+----+
 *                        | SMQ Nodes         |
 *                        |----|----|----|----|
 *                 Node # |  0 |  1 |  2 | ...|
 *                        |----|----|----|----|
 * Starting Block Index # |  0 |  3 |  8 | ...|
 *                        |----|----|----|----|
 *            # of blocks |  3 |  5 |  1 | ...|
 *                        +----+----+----+----+
 *
 * Header: Contains version numbers for software compatibility to ensure
 * that both producers and consumers on the AP and subsystems know how to
 * read from and write to the queue.
 * Both the producer and consumer versions are 1.
 *     +---------+-------------------+
 *     | Size    | Field             |
 *     +---------+-------------------+
 *     | 1 byte  | Producer Version  |
 *     +---------+-------------------+
 *     | 1 byte  | Consumer Version  |
 *     +---------+-------------------+
 *
 * Data: The data portion contains multiple blocks [0..N] of a fixed size.
 * The block size SM_BLOCKSIZE is fixed to 128 bytes for header version #1.
 * Payload sent from the debug agent app is split (if necessary) and placed
 * in these blocks. The first data block is placed at the next 8 byte aligned
 * address after the header.
 *
 * The number of blocks for a given SMEM allocation is derived as follows:
 *   Number of Blocks = ((Total Size - Alignment - Size of Header
 *		- Size of SMQIn - Size of SMQOut)/(SM_BLOCKSIZE))
 *
 * The producer maintains a private block map of each of these blocks to
 * determine which of these blocks in the queue is available and which are free.
 *
 * Control:
 * The control portion contains a list of nodes [0..N] where N is number
 * of available data blocks. Each node identifies the data
 * block indexes that contain a particular debug message to be transferred,
 * and the number of blocks it took to hold the contents of the message.
 *
 * Each node has the following structure:
 *     +---------+-------------------+
 *     | Size    | Field             |
 *     +---------+-------------------+
 *     | 2 bytes |Staring Block Index|
 *     +---------+-------------------+
 *     | 2 bytes |Number of Blocks   |
 *     +---------+-------------------+
 *
 * The producer and the consumer update different parts of the control channel
 * (SMQOut / SMQIn) respectively. Each of these control data structures contains
 * information about the last node that was written / read, and the actual nodes
 * that were written/read.
 *
 * SMQOut Structure (R/W by producer, R by consumer):
 *     +---------+-------------------+
 *     | Size    | Field             |
 *     +---------+-------------------+
 *     | 4 bytes | Magic Init Number |
 *     +---------+-------------------+
 *     | 4 bytes | Reset             |
 *     +---------+-------------------+
 *     | 4 bytes | Last Sent Index   |
 *     +---------+-------------------+
 *     | 4 bytes | Index Free Read   |
 *     +---------+-------------------+
 *
 * SMQIn Structure (R/W by consumer, R by producer):
 *     +---------+-------------------+
 *     | Size    | Field             |
 *     +---------+-------------------+
 *     | 4 bytes | Magic Init Number |
 *     +---------+-------------------+
 *     | 4 bytes | Reset ACK         |
 *     +---------+-------------------+
 *     | 4 bytes | Last Read Index   |
 *     +---------+-------------------+
 *     | 4 bytes | Index Free Write  |
 *     +---------+-------------------+
 *
 * Magic Init Number:
 * Both SMQ Out and SMQ In initialize this field with a predefined magic
 * number so as to make sure that both the consumer and producer blocks
 * have fully initialized and have valid data in the shared memory control area.
 *	Producer Magic #: 0xFF00FF01
 *	Consumer Magic #: 0xFF00FF02
 */
static int smq_ctor(struct smq *smq, void *base_addr, int size,
	enum smq_type type, struct mutex *lock_ptr)
{
	int num_blocks;
	uint8_t *pb_orig;
	uint8_t *pb;
	uint32_t i;
	int err;

	if (SMQ_MAGIC_INIT == smq->initialized) {
		err = SMQ_EBADPARM;
		goto bail;
	}

	if (!base_addr || !size) {
		err = SMQ_EBADPARM;
		goto bail;
	}

	if (type == PRODUCER)
		smq->lock = lock_ptr;

	pb_orig = (uint8_t *)base_addr;
	smq->hdr = (struct smq_hdr *)pb_orig;
	pb = pb_orig;
	pb += sizeof(struct smq_hdr);
	pb = PTR_ALIGN(pb, 8);
	size -= pb - (uint8_t *)pb_orig;
	num_blocks = (int)((size - sizeof(struct smq_out_state) -
		sizeof(struct smq_in_state))/(SM_BLOCKSIZE +
		sizeof(struct smq_node) * 2));
	if (0 >= num_blocks) {
		err = SMQ_ENOMEMORY;
		goto bail;
	}

	smq->blocks = pb;
	smq->num_blocks = num_blocks;
	pb += num_blocks * SM_BLOCKSIZE;
	smq->out = (struct smq_out *)pb;
	pb += sizeof(struct smq_out_state) + (num_blocks *
		sizeof(struct smq_node));
	smq->in = (struct smq_in *)pb;
	smq->type = type;
	if (PRODUCER == type) {
		smq->hdr->producer_version = SM_VERSION;
		for (i = 0; i < smq->num_blocks; i++)
			(smq->out->sent + i)->index_block = 0xFFFF;

		err = smq_blockmap_ctor(&smq->block_map, smq->num_blocks);
		if (SMQ_SUCCESS != err)
			goto bail;

		smq->out->s.index_sent_write = 0;
		smq->out->s.index_free_read = 0;
		if (smq->out->s.init == SMQ_MAGIC_PRODUCER) {
			smq->out->s.index_check_queue_for_reset += 1;
		} else {
			smq->out->s.index_check_queue_for_reset = 1;
			smq->out->s.init = SMQ_MAGIC_PRODUCER;
		}
	} else {
		smq->hdr->consumer_version = SM_VERSION;
		for (i = 0; i < smq->num_blocks; i++)
			(smq->in->free + i)->index_block = 0xFFFF;

		smq->in->s.index_sent_read = 0;
		smq->in->s.index_free_write = 0;
		if (smq->out->s.init == SMQ_MAGIC_PRODUCER) {
			smq->in->s.index_check_queue_for_reset_ack =
				smq->out->s.index_check_queue_for_reset;
		} else {
			smq->in->s.index_check_queue_for_reset_ack = 0;
		}

		smq->in->s.init = SMQ_MAGIC_CONSUMER;
	}
	smq->initialized = SMQ_MAGIC_INIT;
	err = SMQ_SUCCESS;

bail:
	return err;
}

static void send_interrupt_to_subsystem(struct rdbg_data *rdbgdata)
{
	int offset = rdbgdata->gpio_out_offset;
	int val = 1 ^ gpio_get_value(rdbgdata->out.gpio_base_id + offset);

	gpio_set_value(rdbgdata->out.gpio_base_id + offset, val);
	rdbgdata->gpio_out_offset = (offset + 1) % 32;

	dev_dbg(rdbgdata->device, "%s: sent interrupt %d to subsystem",
		__func__, val);
}

static irqreturn_t on_interrupt_from(int irq, void *ptr)
{
	struct rdbg_data *rdbgdata = (struct rdbg_data *) ptr;

	dev_dbg(rdbgdata->device, "%s: Received interrupt %d from subsystem",
		__func__, irq);

	complete(&(rdbgdata->work));
	return IRQ_HANDLED;
}

static int initialize_smq(struct rdbg_data *rdbgdata)
{
	int err = 0;
	unsigned char *smem_consumer_buffer = rdbgdata->smem_addr;

	smem_consumer_buffer += (rdbgdata->smem_size/2);

	if (smq_ctor(&(rdbgdata->producer_smrb), (void *)(rdbgdata->smem_addr),
		((rdbgdata->smem_size)/2), PRODUCER, &rdbgdata->write_mutex)) {
		dev_err(rdbgdata->device, "%s: smq producer allocation failed",
			__func__);
		err = -ENOMEM;
		goto bail;
	}

	if (smq_ctor(&(rdbgdata->consumer_smrb), (void *)smem_consumer_buffer,
		((rdbgdata->smem_size)/2), CONSUMER, NULL)) {
		dev_err(rdbgdata->device, "%s: smq conmsumer allocation failed",
			__func__);
		err = -ENOMEM;
	}

bail:
	return err;

}

static int rdbg_open(struct inode *inode, struct file *filp)
{
	int device_id = -1;
	struct rdbg_device *device = &g_rdbg_instance;
	struct rdbg_data *rdbgdata = NULL;
	int err = 0;

	if (!inode || !device->rdbg_data) {
		pr_err("Memory not allocated yet");
		err = -ENODEV;
		goto bail;
	}

	device_id = MINOR(inode->i_rdev);
	rdbgdata = &device->rdbg_data[device_id];

	if (rdbgdata->device_opened) {
		dev_err(rdbgdata->device, "%s: Device already opened",
			__func__);
		err = -EEXIST;
		goto bail;
	}

	rdbgdata->smem_size = proc_info[device_id].smem_buffer_size;
	if (!rdbgdata->smem_size) {
		dev_err(rdbgdata->device, "%s: smem not initialized", __func__);
		err = -ENOMEM;
		goto bail;
	}

	rdbgdata->smem_addr = smem_find(proc_info[device_id].smem_buffer_addr,
		rdbgdata->smem_size, 0, SMEM_ANY_HOST_FLAG);
	if (!rdbgdata->smem_addr) {
		dev_err(rdbgdata->device, "%s: Could not allocate smem memory",
			__func__);
		err = -ENOMEM;
		goto bail;
	}
	dev_dbg(rdbgdata->device, "%s: SMEM address=0x%lx smem_size=%d",
		__func__, (unsigned long)rdbgdata->smem_addr,
		(unsigned int)rdbgdata->smem_size);

	if (check_subsystem_debug_enabled(rdbgdata->smem_addr,
		rdbgdata->smem_size/2)) {
		dev_err(rdbgdata->device, "%s: Subsystem %s is not debug enabled",
			__func__, proc_info[device_id].name);
		err = -ECOMM;
		goto bail;
	}

	init_completion(&rdbgdata->work);

	err = request_irq(rdbgdata->in.irq_base_id, on_interrupt_from,
			IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
			proc_info[device_id].name,
			(void *)&device->rdbg_data[device_id]);
	if (err) {
		dev_err(rdbgdata->device,
			"%s: Failed to register interrupt.Err=%d,irqid=%d.",
			__func__, err, rdbgdata->in.irq_base_id);
		goto irq_bail;
	}

	err = enable_irq_wake(rdbgdata->in.irq_base_id);
	if (err < 0) {
		dev_dbg(rdbgdata->device, "enable_irq_wake() failed with err=%d",
			err);
		err = 0;
	}

	mutex_init(&rdbgdata->write_mutex);

	err = initialize_smq(rdbgdata);
	if (err) {
		dev_err(rdbgdata->device, "Error initializing smq. Err=%d",
			err);
		goto smq_bail;
	}

	rdbgdata->device_opened = 1;

	filp->private_data = (void *)rdbgdata;

	return 0;

smq_bail:
	smq_dtor(&(rdbgdata->producer_smrb));
	smq_dtor(&(rdbgdata->consumer_smrb));
	mutex_destroy(&rdbgdata->write_mutex);
irq_bail:
	free_irq(rdbgdata->in.irq_base_id, (void *)
		&device->rdbg_data[device_id]);
bail:
	return err;
}

static int rdbg_release(struct inode *inode, struct file *filp)
{
	int device_id = -1;
	struct rdbg_device *rdbgdevice = &g_rdbg_instance;
	struct rdbg_data *rdbgdata = NULL;
	int err = 0;

	if (!inode || !rdbgdevice->rdbg_data) {
		pr_err("Memory not allocated yet");
		err = -ENODEV;
		goto bail;
	}

	device_id = MINOR(inode->i_rdev);
	rdbgdata = &rdbgdevice->rdbg_data[device_id];

	if (rdbgdata->device_opened == 1) {
		dev_dbg(rdbgdata->device, "%s: Destroying %s.", __func__,
			proc_info[device_id].name);
		rdbgdata->device_opened = 0;
		complete(&(rdbgdata->work));
		free_irq(rdbgdata->in.irq_base_id, (void *)
			&rdbgdevice->rdbg_data[device_id]);
		if (rdbgdevice->rdbg_data[device_id].producer_smrb.initialized)
			smq_dtor(&(rdbgdevice->rdbg_data[device_id].
				producer_smrb));
		if (rdbgdevice->rdbg_data[device_id].consumer_smrb.initialized)
			smq_dtor(&(rdbgdevice->rdbg_data[device_id].
				consumer_smrb));
		mutex_destroy(&rdbgdata->write_mutex);
	}

	filp->private_data = NULL;

bail:
	return err;
}

static ssize_t rdbg_read(struct file *filp, char __user *buf, size_t size,
	loff_t *offset)
{
	int err = 0;
	struct rdbg_data *rdbgdata = filp->private_data;
	void *p_sent_buffer = NULL;
	int nsize = 0;
	int more = 0;

	if (!rdbgdata) {
		pr_err("Invalid argument");
		err = -EINVAL;
		goto bail;
	}

	dev_dbg(rdbgdata->device, "%s: In receive", __func__);
	err = wait_for_completion_interruptible(&(rdbgdata->work));
	if (err) {
		dev_err(rdbgdata->device, "%s: Error in wait", __func__);
		goto bail;
	}

	smq_check_queue_reset(&(rdbgdata->consumer_smrb),
		&(rdbgdata->producer_smrb));
	if (SMQ_SUCCESS != smq_receive(&(rdbgdata->consumer_smrb),
			&p_sent_buffer, &nsize, &more)) {
		dev_err(rdbgdata->device, "%s: Error in smq_recv(). Err code = %d",
			__func__, err);
		err = -ENODATA;
		goto bail;
	}

	size = ((size < nsize) ? size : nsize);
	err = copy_to_user(buf, p_sent_buffer, size);
	if (err != 0) {
		dev_err(rdbgdata->device, "%s: Error in copy_to_user(). Err code = %d",
			__func__, err);
		err = -ENODATA;
		goto bail;
	}

	smq_free(&(rdbgdata->consumer_smrb), p_sent_buffer);
	err = size;
	dev_dbg(rdbgdata->device, "%s: Read data to buffer with address 0x%lx",
		__func__, (unsigned long) buf);

bail:
	return err;
}

static ssize_t rdbg_write(struct file *filp, const char __user *buf,
	size_t size, loff_t *offset)
{
	int err = 0;
	int num_retries = 0;
	struct rdbg_data *rdbgdata = filp->private_data;

	if (!rdbgdata) {
		pr_err("Invalid argument");
		err = -EINVAL;
		goto bail;
	}

	do {
		err = smq_alloc_send(&(rdbgdata->producer_smrb), buf, size);
		dev_dbg(rdbgdata->device, "%s, smq_alloc_send returned %d.",
			__func__, err);
	} while (err != 0 && num_retries++ < MAX_RETRIES);

	if (err != 0) {
		err = -ECOMM;
		goto bail;
	}

	send_interrupt_to_subsystem(rdbgdata);

	err = size;

bail:
	return err;
}


static const struct file_operations rdbg_fops = {
	.open = rdbg_open,
	.read =  rdbg_read,
	.write =  rdbg_write,
	.release = rdbg_release,
};

static int register_smp2p(char *node_name, struct gpio_info *gpio_info_ptr)
{
	struct device_node *node = NULL;
	int cnt = 0;
	int id = 0;

	node = of_find_compatible_node(NULL, NULL, node_name);
	if (node) {
		cnt = of_gpio_count(node);
		if (cnt && gpio_info_ptr) {
			id = of_get_gpio(node, 0);
			gpio_info_ptr->gpio_base_id = id;
			gpio_info_ptr->irq_base_id = gpio_to_irq(id);
			return 0;
		}
	}
	return -EINVAL;
}

static int __init rdbg_init(void)
{
	int err = 0;
	struct rdbg_device *rdbgdevice = &g_rdbg_instance;
	int minor = 0;
	int major = 0;
	int minor_nodes_created = 0;

	char *rdbg_compatible_string = "qcom,smp2pgpio_client_rdbg_";
	int max_len = strlen(rdbg_compatible_string) + strlen("xx_out");

	char *node_name = kcalloc(max_len, sizeof(char), GFP_KERNEL);

	if (!node_name) {
		err = -ENOMEM;
		goto bail;
	}

	if (rdbgdevice->num_devices < 1 ||
		rdbgdevice->num_devices > SMP2P_NUM_PROCS) {
		pr_err("rgdb: invalid num_devices");
		err = -EDOM;
		goto name_bail;
	}

	rdbgdevice->rdbg_data = kcalloc(rdbgdevice->num_devices,
		sizeof(struct rdbg_data), GFP_KERNEL);
	if (!rdbgdevice->rdbg_data) {
		err = -ENOMEM;
		goto name_bail;
	}

	err = alloc_chrdev_region(&rdbgdevice->dev_no, 0,
		rdbgdevice->num_devices, "rdbgctl");
	if (err) {
		pr_err("Error in alloc_chrdev_region.");
		goto data_bail;
	}
	major = MAJOR(rdbgdevice->dev_no);

	cdev_init(&rdbgdevice->cdev, &rdbg_fops);
	rdbgdevice->cdev.owner = THIS_MODULE;
	err = cdev_add(&rdbgdevice->cdev, MKDEV(major, 0),
		rdbgdevice->num_devices);
	if (err) {
		pr_err("Error in cdev_add");
		goto chrdev_bail;
	}

	rdbgdevice->class = class_create(THIS_MODULE, "rdbg");
	if (IS_ERR(rdbgdevice->class)) {
		err = PTR_ERR(rdbgdevice->class);
		pr_err("Error in class_create");
		goto cdev_bail;
	}

	for (minor = 0; minor < rdbgdevice->num_devices; minor++) {
		if (!proc_info[minor].name)
			continue;

		if (snprintf(node_name, max_len, "%s%d_in",
			rdbg_compatible_string, minor) <= 0) {
			pr_err("Error in snprintf");
			err = -ENOMEM;
			goto device_bail;
		}

		if (register_smp2p(node_name,
			&rdbgdevice->rdbg_data[minor].in)) {
			pr_debug("No incoming device tree entry found for %s",
				proc_info[minor].name);
			continue;
		}

		if (snprintf(node_name, max_len, "%s%d_out",
			rdbg_compatible_string, minor) <= 0) {
			pr_err("Error in snprintf");
			err = -ENOMEM;
			goto device_bail;
		}

		if (register_smp2p(node_name,
			&rdbgdevice->rdbg_data[minor].out)) {
			pr_err("No outgoing device tree entry found for %s",
				proc_info[minor].name);
			err = -EINVAL;
			goto device_bail;
		}

		rdbgdevice->rdbg_data[minor].device = device_create(
			rdbgdevice->class, NULL, MKDEV(major, minor),
			NULL, "%s", proc_info[minor].name);
		if (IS_ERR(rdbgdevice->rdbg_data[minor].device)) {
			err = PTR_ERR(rdbgdevice->rdbg_data[minor].device);
			pr_err("Error in device_create");
			goto device_bail;
		}
		rdbgdevice->rdbg_data[minor].device_initialized = 1;
		minor_nodes_created++;
		dev_dbg(rdbgdevice->rdbg_data[minor].device,
			"%s: created /dev/%s c %d %d'", __func__,
			proc_info[minor].name, major, minor);
	}

	if (!minor_nodes_created) {
		pr_err("No device tree entries found");
		err = -EINVAL;
		goto class_bail;
	}

	goto name_bail;

device_bail:
	for (--minor; minor >= 0; minor--) {
		if (rdbgdevice->rdbg_data[minor].device_initialized)
			device_destroy(rdbgdevice->class,
				MKDEV(MAJOR(rdbgdevice->dev_no), minor));
	}
class_bail:
	class_destroy(rdbgdevice->class);
cdev_bail:
	cdev_del(&rdbgdevice->cdev);
chrdev_bail:
	unregister_chrdev_region(rdbgdevice->dev_no, rdbgdevice->num_devices);
data_bail:
	kfree(rdbgdevice->rdbg_data);
name_bail:
	kfree(node_name);
bail:
	return err;
}

static void __exit rdbg_exit(void)
{
	struct rdbg_device *rdbgdevice = &g_rdbg_instance;
	int minor;

	for (minor = 0; minor < rdbgdevice->num_devices; minor++) {
		if (rdbgdevice->rdbg_data[minor].device_initialized) {
			device_destroy(rdbgdevice->class,
				MKDEV(MAJOR(rdbgdevice->dev_no), minor));
		}
	}
	class_destroy(rdbgdevice->class);
	cdev_del(&rdbgdevice->cdev);
	unregister_chrdev_region(rdbgdevice->dev_no, 1);
	kfree(rdbgdevice->rdbg_data);
}

module_init(rdbg_init);
module_exit(rdbg_exit);

MODULE_DESCRIPTION("rdbg module");
MODULE_LICENSE("GPL v2");