/* Copyright (c) 2008-2009, 2011-2014 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/err.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_address.h>

#include <asm/system.h>

#include <mach/msm_iomap.h>
#include <mach/remote_spinlock.h>
#include <mach/dal.h>
#include <mach/msm_smem.h>
#include "smd_private.h"


#define SPINLOCK_PID_APPS 1

#define AUTO_MODE -1
#define DEKKERS_MODE 1
#define SWP_MODE 2
#define LDREX_MODE 3
#define SFPB_MODE 4

#if defined(CONFIG_MSM_REMOTE_SPINLOCK_DEKKERS) ||\
		defined(CONFIG_MSM_REMOTE_SPINLOCK_SWP) ||\
		defined(CONFIG_MSM_REMOTE_SPINLOCK_LDREX) ||\
		defined(CONFIG_MSM_REMOTE_SPINLOCK_SFPB)

#ifdef CONFIG_MSM_REMOTE_SPINLOCK_DEKKERS
/*
 * Use Dekker's algorithm when LDREX/STREX and SWP are unavailable for
 * shared memory
 */
#define CURRENT_MODE_INIT DEKKERS_MODE;
#endif

#ifdef CONFIG_MSM_REMOTE_SPINLOCK_SWP
/* Use SWP-based locks when LDREX/STREX are unavailable for shared memory. */
#define CURRENT_MODE_INIT SWP_MODE;
#endif

#ifdef CONFIG_MSM_REMOTE_SPINLOCK_LDREX
/* Use LDREX/STREX for shared memory locking, when available */
#define CURRENT_MODE_INIT LDREX_MODE;
#endif

#ifdef CONFIG_MSM_REMOTE_SPINLOCK_SFPB
/* Use SFPB Hardware Mutex Registers */
#define CURRENT_MODE_INIT SFPB_MODE;
#endif

#else
/* Use DT info to configure with a fallback to LDREX if DT is missing */
#define CURRENT_MODE_INIT AUTO_MODE;
#endif

static int current_mode = CURRENT_MODE_INIT;

static int is_hw_lock_type;
static DEFINE_MUTEX(ops_init_lock);

struct spinlock_ops {
	void (*lock)(raw_remote_spinlock_t *lock);
	void (*unlock)(raw_remote_spinlock_t *lock);
	int (*trylock)(raw_remote_spinlock_t *lock);
	int (*release)(raw_remote_spinlock_t *lock, uint32_t pid);
	int (*owner)(raw_remote_spinlock_t *lock);
	void (*lock_rlock_id)(raw_remote_spinlock_t *lock, uint32_t tid);
	void (*unlock_rlock)(raw_remote_spinlock_t *lock);
};

static struct spinlock_ops current_ops;

static int remote_spinlock_init_address(int id, _remote_spinlock_t *lock);

/* dekkers implementation --------------------------------------------------- */
#define DEK_LOCK_REQUEST		1
#define DEK_LOCK_YIELD			(!DEK_LOCK_REQUEST)
#define DEK_YIELD_TURN_SELF		0
static void __raw_remote_dek_spin_lock(raw_remote_spinlock_t *lock)
{
	lock->dek.self_lock = DEK_LOCK_REQUEST;

	while (lock->dek.other_lock) {

		if (lock->dek.next_yield == DEK_YIELD_TURN_SELF)
			lock->dek.self_lock = DEK_LOCK_YIELD;

		while (lock->dek.other_lock)
			;

		lock->dek.self_lock = DEK_LOCK_REQUEST;
	}
	lock->dek.next_yield = DEK_YIELD_TURN_SELF;

	smp_mb();
}

static int __raw_remote_dek_spin_trylock(raw_remote_spinlock_t *lock)
{
	lock->dek.self_lock = DEK_LOCK_REQUEST;

	if (lock->dek.other_lock) {
		lock->dek.self_lock = DEK_LOCK_YIELD;
		return 0;
	}

	lock->dek.next_yield = DEK_YIELD_TURN_SELF;

	smp_mb();
	return 1;
}

static void __raw_remote_dek_spin_unlock(raw_remote_spinlock_t *lock)
{
	smp_mb();

	lock->dek.self_lock = DEK_LOCK_YIELD;
}

static int __raw_remote_dek_spin_release(raw_remote_spinlock_t *lock,
		uint32_t pid)
{
	return -EPERM;
}

static int __raw_remote_dek_spin_owner(raw_remote_spinlock_t *lock)
{
	return -EPERM;
}
/* end dekkers implementation ----------------------------------------------- */

#ifndef CONFIG_THUMB2_KERNEL
/* swp implementation ------------------------------------------------------- */
static void __raw_remote_swp_spin_lock(raw_remote_spinlock_t *lock)
{
	unsigned long tmp;

	__asm__ __volatile__(
"1:     swp     %0, %2, [%1]\n"
"       teq     %0, #0\n"
"       bne     1b"
	: "=&r" (tmp)
	: "r" (&lock->lock), "r" (1)
	: "cc");

	smp_mb();
}

static int __raw_remote_swp_spin_trylock(raw_remote_spinlock_t *lock)
{
	unsigned long tmp;

	__asm__ __volatile__(
"       swp     %0, %2, [%1]\n"
	: "=&r" (tmp)
	: "r" (&lock->lock), "r" (1)
	: "cc");

	if (tmp == 0) {
		smp_mb();
		return 1;
	}
	return 0;
}

static void __raw_remote_swp_spin_unlock(raw_remote_spinlock_t *lock)
{
	int lock_owner;

	smp_mb();
	lock_owner = readl_relaxed(&lock->lock);
	if (lock_owner != SPINLOCK_PID_APPS) {
		pr_err("%s: spinlock not owned by Apps (actual owner is %d)\n",
				__func__, lock_owner);
	}

	__asm__ __volatile__(
"       str     %1, [%0]"
	:
	: "r" (&lock->lock), "r" (0)
	: "cc");
}
/* end swp implementation --------------------------------------------------- */
#endif

/* ldrex implementation ----------------------------------------------------- */
static char *ldrex_compatible_string = "qcom,ipc-spinlock-ldrex";

static void __raw_remote_ex_spin_lock(raw_remote_spinlock_t *lock)
{
	unsigned long tmp;

	__asm__ __volatile__(
"1:     ldrex   %0, [%1]\n"
"       teq     %0, #0\n"
"       strexeq %0, %2, [%1]\n"
"       teqeq   %0, #0\n"
"       bne     1b"
	: "=&r" (tmp)
	: "r" (&lock->lock), "r" (SPINLOCK_PID_APPS)
	: "cc");

	smp_mb();
}

static int __raw_remote_ex_spin_trylock(raw_remote_spinlock_t *lock)
{
	unsigned long tmp;

	__asm__ __volatile__(
"       ldrex   %0, [%1]\n"
"       teq     %0, #0\n"
"       strexeq %0, %2, [%1]\n"
	: "=&r" (tmp)
	: "r" (&lock->lock), "r" (SPINLOCK_PID_APPS)
	: "cc");

	if (tmp == 0) {
		smp_mb();
		return 1;
	}
	return 0;
}

static void __raw_remote_ex_spin_unlock(raw_remote_spinlock_t *lock)
{
	int lock_owner;

	smp_mb();
	lock_owner = readl_relaxed(&lock->lock);
	if (lock_owner != SPINLOCK_PID_APPS) {
		pr_err("%s: spinlock not owned by Apps (actual owner is %d)\n",
				__func__, lock_owner);
	}

	__asm__ __volatile__(
"       str     %1, [%0]\n"
	:
	: "r" (&lock->lock), "r" (0)
	: "cc");
}
/* end ldrex implementation ------------------------------------------------- */

/* sfpb implementation ------------------------------------------------------ */
#define SFPB_SPINLOCK_COUNT 8
#define MSM_SFPB_MUTEX_REG_BASE 0x01200600
#define MSM_SFPB_MUTEX_REG_SIZE	(33 * 4)
#define SFPB_SPINLOCK_OFFSET 4
#define SFPB_SPINLOCK_SIZE 4

static uint32_t lock_count;
static phys_addr_t reg_base;
static uint32_t reg_size;
static uint32_t lock_offset; /* offset into the hardware block before lock 0 */
static uint32_t lock_size;

static void *hw_mutex_reg_base;
static DEFINE_MUTEX(hw_map_init_lock);

static char *sfpb_compatible_string = "qcom,ipc-spinlock-sfpb";

static int init_hw_mutex(struct device_node *node)
{
	struct resource r;
	int rc;

	rc = of_address_to_resource(node, 0, &r);
	if (rc)
		BUG();

	rc = of_property_read_u32(node, "qcom,num-locks", &lock_count);
	if (rc)
		BUG();

	reg_base = r.start;
	reg_size = (uint32_t)(resource_size(&r));
	lock_offset = 0;
	lock_size = reg_size / lock_count;

	return 0;
}

static void find_and_init_hw_mutex(void)
{
	struct device_node *node;

	node = of_find_compatible_node(NULL, NULL, sfpb_compatible_string);
	if (node) {
		init_hw_mutex(node);
	} else {
		lock_count = SFPB_SPINLOCK_COUNT;
		reg_base = MSM_SFPB_MUTEX_REG_BASE;
		reg_size = MSM_SFPB_MUTEX_REG_SIZE;
		lock_offset = SFPB_SPINLOCK_OFFSET;
		lock_size = SFPB_SPINLOCK_SIZE;
	}
	hw_mutex_reg_base = ioremap(reg_base, reg_size);
	BUG_ON(hw_mutex_reg_base == NULL);
}

static int remote_spinlock_init_address_hw(int id, _remote_spinlock_t *lock)
{
	/*
	 * Optimistic locking.  Init only needs to be done once by the first
	 * caller.  After that, serializing inits between different callers
	 * is unnecessary.  The second check after the lock ensures init
	 * wasn't previously completed by someone else before the lock could
	 * be grabbed.
	 */
	if (!hw_mutex_reg_base) {
		mutex_lock(&hw_map_init_lock);
		if (!hw_mutex_reg_base)
			find_and_init_hw_mutex();
		mutex_unlock(&hw_map_init_lock);
	}

	if (id >= lock_count)
		return -EINVAL;

	*lock = hw_mutex_reg_base + lock_offset + id * lock_size;
	return 0;
}

static void __raw_remote_sfpb_spin_lock(raw_remote_spinlock_t *lock)
{
	do {
		writel_relaxed(SPINLOCK_PID_APPS, lock);
		smp_mb();
	} while (readl_relaxed(lock) != SPINLOCK_PID_APPS);
}

static int __raw_remote_sfpb_spin_trylock(raw_remote_spinlock_t *lock)
{
	writel_relaxed(SPINLOCK_PID_APPS, lock);
	smp_mb();
	return readl_relaxed(lock) == SPINLOCK_PID_APPS;
}

static void __raw_remote_sfpb_spin_unlock(raw_remote_spinlock_t *lock)
{
	int lock_owner;

	lock_owner = readl_relaxed(lock);
	if (lock_owner != SPINLOCK_PID_APPS) {
		pr_err("%s: spinlock not owned by Apps (actual owner is %d)\n",
				__func__, lock_owner);
	}

	writel_relaxed(0, lock);
	smp_mb();
}

static void __raw_remote_sfpb_spin_lock_rlock_id(raw_remote_spinlock_t *lock,
						 uint32_t tid)
{
	if (unlikely(!tid)) {
		pr_err("%s: unsupported rlock tid=0\n", __func__);
		BUG();
	}

	do {
		writel_relaxed(tid, lock);
		smp_mb();
	} while (readl_relaxed(lock) != tid);
}

static void __raw_remote_sfpb_spin_unlock_rlock(raw_remote_spinlock_t *lock)
{
	writel_relaxed(0, lock);
	smp_mb();
}

/* end sfpb implementation -------------------------------------------------- */

/* common spinlock API ------------------------------------------------------ */
/**
 * Release spinlock if it is owned by @pid.
 *
 * This is only to be used for situations where the processor owning
 * the spinlock has crashed and the spinlock must be released.
 *
 * @lock: lock structure
 * @pid: processor ID of processor to release
 */
static int __raw_remote_gen_spin_release(raw_remote_spinlock_t *lock,
		uint32_t pid)
{
	int ret = 1;

	if (readl_relaxed(&lock->lock) == pid) {
		writel_relaxed(0, &lock->lock);
		wmb();
		ret = 0;
	}
	return ret;
}

/**
 * Return owner of the spinlock.
 *
 * @lock: pointer to lock structure
 * @returns: >= 0 owned PID; < 0 for error case
 *
 * Used for testing.  PID's are assumed to be 31 bits or less.
 */
static int __raw_remote_gen_spin_owner(raw_remote_spinlock_t *lock)
{
	rmb();
	return readl_relaxed(&lock->lock);
}


static int dt_node_is_valid(const struct device_node *node)
{
	const char *status;
	int statlen;

	status = of_get_property(node, "status", &statlen);
	if (status == NULL)
		return 1;

	if (statlen > 0) {
		if (!strcmp(status, "okay") || !strcmp(status, "ok"))
			return 1;
	}

	return 0;
}

static void initialize_ops(void)
{
	struct device_node *node;

	switch (current_mode) {
	case DEKKERS_MODE:
		current_ops.lock = __raw_remote_dek_spin_lock;
		current_ops.unlock = __raw_remote_dek_spin_unlock;
		current_ops.trylock = __raw_remote_dek_spin_trylock;
		current_ops.release = __raw_remote_dek_spin_release;
		current_ops.owner = __raw_remote_dek_spin_owner;
		is_hw_lock_type = 0;
		break;
#ifndef CONFIG_THUMB2_KERNEL
	case SWP_MODE:
		current_ops.lock = __raw_remote_swp_spin_lock;
		current_ops.unlock = __raw_remote_swp_spin_unlock;
		current_ops.trylock = __raw_remote_swp_spin_trylock;
		current_ops.release = __raw_remote_gen_spin_release;
		current_ops.owner = __raw_remote_gen_spin_owner;
		is_hw_lock_type = 0;
		break;
#endif
	case LDREX_MODE:
		current_ops.lock = __raw_remote_ex_spin_lock;
		current_ops.unlock = __raw_remote_ex_spin_unlock;
		current_ops.trylock = __raw_remote_ex_spin_trylock;
		current_ops.release = __raw_remote_gen_spin_release;
		current_ops.owner = __raw_remote_gen_spin_owner;
		is_hw_lock_type = 0;
		break;
	case SFPB_MODE:
		current_ops.lock = __raw_remote_sfpb_spin_lock;
		current_ops.unlock = __raw_remote_sfpb_spin_unlock;
		current_ops.trylock = __raw_remote_sfpb_spin_trylock;
		current_ops.release = __raw_remote_gen_spin_release;
		current_ops.owner = __raw_remote_gen_spin_owner;
		current_ops.lock_rlock_id =
				__raw_remote_sfpb_spin_lock_rlock_id;
		current_ops.unlock_rlock = __raw_remote_sfpb_spin_unlock_rlock;
		is_hw_lock_type = 1;
		break;
	case AUTO_MODE:
		/*
		 * of_find_compatible_node() returns a valid pointer even if
		 * the status property is "disabled", so the validity needs
		 * to be checked
		 */
		node = of_find_compatible_node(NULL, NULL,
						sfpb_compatible_string);
		if (node && dt_node_is_valid(node)) {
			current_ops.lock = __raw_remote_sfpb_spin_lock;
			current_ops.unlock = __raw_remote_sfpb_spin_unlock;
			current_ops.trylock = __raw_remote_sfpb_spin_trylock;
			current_ops.release = __raw_remote_gen_spin_release;
			current_ops.owner = __raw_remote_gen_spin_owner;
			current_ops.lock_rlock_id =
					__raw_remote_sfpb_spin_lock_rlock_id;
			current_ops.unlock_rlock =
					__raw_remote_sfpb_spin_unlock_rlock;
			is_hw_lock_type = 1;
			break;
		}

		node = of_find_compatible_node(NULL, NULL,
						ldrex_compatible_string);
		if (node && dt_node_is_valid(node)) {
			current_ops.lock = __raw_remote_ex_spin_lock;
			current_ops.unlock = __raw_remote_ex_spin_unlock;
			current_ops.trylock = __raw_remote_ex_spin_trylock;
			current_ops.release = __raw_remote_gen_spin_release;
			current_ops.owner = __raw_remote_gen_spin_owner;
			is_hw_lock_type = 0;
			break;
		}

		current_ops.lock = __raw_remote_ex_spin_lock;
		current_ops.unlock = __raw_remote_ex_spin_unlock;
		current_ops.trylock = __raw_remote_ex_spin_trylock;
		current_ops.release = __raw_remote_gen_spin_release;
		current_ops.owner = __raw_remote_gen_spin_owner;
		is_hw_lock_type = 0;
		pr_warn("Falling back to LDREX remote spinlock implementation");
		break;
	default:
		BUG();
		break;
	}
}

/**
 * Release all spinlocks owned by @pid.
 *
 * This is only to be used for situations where the processor owning
 * spinlocks has crashed and the spinlocks must be released.
 *
 * @pid - processor ID of processor to release
 */
static void remote_spin_release_all_locks(uint32_t pid, int count)
{
	int n;
	 _remote_spinlock_t lock;

	if (pid >= REMOTE_SPINLOCK_NUM_PID) {
		pr_err("%s: unsupported PID %d\n", __func__, pid);
		return;
	}

	for (n = 0; n < count; ++n) {
		if (remote_spinlock_init_address(n, &lock) == 0)
			_remote_spin_release(&lock, pid);
	}
}

void _remote_spin_release_all(uint32_t pid)
{
	remote_spin_release_all_locks(pid, lock_count);
}

static int
remote_spinlock_dal_init(const char *chunk_name, _remote_spinlock_t *lock)
{
	void *dal_smem_start, *dal_smem_end;
	uint32_t dal_smem_size;
	struct dal_chunk_header *cur_header;

	if (!chunk_name)
		return -EINVAL;

	dal_smem_start = smem_get_entry(SMEM_DAL_AREA, &dal_smem_size);
	if (!dal_smem_start)
		return -ENXIO;

	dal_smem_end = dal_smem_start + dal_smem_size;

	/* Find first chunk header */
	cur_header = (struct dal_chunk_header *)
			(((uint32_t)dal_smem_start + (4095)) & ~4095);
	*lock = NULL;
	while (cur_header->size != 0
		&& ((uint32_t)(cur_header + 1) < (uint32_t)dal_smem_end)) {

		/* Check if chunk name matches */
		if (!strncmp(cur_header->name, chunk_name,
						DAL_CHUNK_NAME_LENGTH)) {
			*lock = (_remote_spinlock_t)&cur_header->lock;
			return 0;
		}
		cur_header = (void *)cur_header + cur_header->size;
	}

	pr_err("%s: DAL remote lock \"%s\" not found.\n", __func__,
		chunk_name);
	return -EINVAL;
}

#define SMEM_SPINLOCK_COUNT 8
#define SMEM_SPINLOCK_ARRAY_SIZE (SMEM_SPINLOCK_COUNT * sizeof(uint32_t))

static int remote_spinlock_init_address_smem(int id, _remote_spinlock_t *lock)
{
	_remote_spinlock_t spinlock_start;

	if (id >= SMEM_SPINLOCK_COUNT)
		return -EINVAL;

	spinlock_start = smem_alloc(SMEM_SPINLOCK_ARRAY,
				    SMEM_SPINLOCK_ARRAY_SIZE);
	if (spinlock_start == NULL)
		return -ENXIO;

	*lock = spinlock_start + id;

	lock_count = SMEM_SPINLOCK_COUNT;

	return 0;
}

static int remote_spinlock_init_address(int id, _remote_spinlock_t *lock)
{
	if (is_hw_lock_type)
		return remote_spinlock_init_address_hw(id, lock);
	else
		return remote_spinlock_init_address_smem(id, lock);
}

int _remote_spin_lock_init(remote_spinlock_id_t id, _remote_spinlock_t *lock)
{
	BUG_ON(id == NULL);

	/*
	 * Optimistic locking.  Init only needs to be done once by the first
	 * caller.  After that, serializing inits between different callers
	 * is unnecessary.  The second check after the lock ensures init
	 * wasn't previously completed by someone else before the lock could
	 * be grabbed.
	 */
	if (!current_ops.lock) {
		mutex_lock(&ops_init_lock);
		if (!current_ops.lock)
			initialize_ops();
		mutex_unlock(&ops_init_lock);
	}

	if (id[0] == 'D' && id[1] == ':') {
		/* DAL chunk name starts after "D:" */
		return remote_spinlock_dal_init(&id[2], lock);
	} else if (id[0] == 'S' && id[1] == ':') {
		/* Single-digit lock ID follows "S:" */
		BUG_ON(id[3] != '\0');

		return remote_spinlock_init_address((((uint8_t)id[2])-'0'),
			lock);
	} else {
		return -EINVAL;
	}
}

/*
 * lock comes in as a pointer to a pointer to the lock location, so it must
 * be dereferenced and casted to the right type for the actual lock
 * implementation functions
 */
void _remote_spin_lock(_remote_spinlock_t *lock)
{
	if (unlikely(!current_ops.lock))
		BUG();
	current_ops.lock((raw_remote_spinlock_t *)(*lock));
}
EXPORT_SYMBOL(_remote_spin_lock);

void _remote_spin_unlock(_remote_spinlock_t *lock)
{
	if (unlikely(!current_ops.unlock))
		BUG();
	current_ops.unlock((raw_remote_spinlock_t *)(*lock));
}
EXPORT_SYMBOL(_remote_spin_unlock);

int _remote_spin_trylock(_remote_spinlock_t *lock)
{
	if (unlikely(!current_ops.trylock))
		BUG();
	return current_ops.trylock((raw_remote_spinlock_t *)(*lock));
}
EXPORT_SYMBOL(_remote_spin_trylock);

int _remote_spin_release(_remote_spinlock_t *lock, uint32_t pid)
{
	if (unlikely(!current_ops.release))
		BUG();
	return current_ops.release((raw_remote_spinlock_t *)(*lock), pid);
}
EXPORT_SYMBOL(_remote_spin_release);

int _remote_spin_owner(_remote_spinlock_t *lock)
{
	if (unlikely(!current_ops.owner))
		BUG();
	return current_ops.owner((raw_remote_spinlock_t *)(*lock));
}
EXPORT_SYMBOL(_remote_spin_owner);

void _remote_spin_lock_rlock_id(_remote_spinlock_t *lock, uint32_t tid)
{
	if (unlikely(!current_ops.lock_rlock_id))
		BUG();
	current_ops.lock_rlock_id((raw_remote_spinlock_t *)(*lock), tid);
}
EXPORT_SYMBOL(_remote_spin_lock_rlock_id);

void _remote_spin_unlock_rlock(_remote_spinlock_t *lock)
{
	if (unlikely(!current_ops.unlock_rlock))
		BUG();
	current_ops.unlock_rlock((raw_remote_spinlock_t *)(*lock));
}
EXPORT_SYMBOL(_remote_spin_unlock_rlock);

/* end common spinlock API -------------------------------------------------- */

/* remote mutex implementation ---------------------------------------------- */
int _remote_mutex_init(struct remote_mutex_id *id, _remote_mutex_t *lock)
{
	BUG_ON(id == NULL);

	lock->delay_us = id->delay_us;
	return _remote_spin_lock_init(id->r_spinlock_id, &(lock->r_spinlock));
}
EXPORT_SYMBOL(_remote_mutex_init);

void _remote_mutex_lock(_remote_mutex_t *lock)
{
	while (!_remote_spin_trylock(&(lock->r_spinlock))) {
		if (lock->delay_us >= 1000)
			msleep(lock->delay_us/1000);
		else
			udelay(lock->delay_us);
	}
}
EXPORT_SYMBOL(_remote_mutex_lock);

void _remote_mutex_unlock(_remote_mutex_t *lock)
{
	_remote_spin_unlock(&(lock->r_spinlock));
}
EXPORT_SYMBOL(_remote_mutex_unlock);

int _remote_mutex_trylock(_remote_mutex_t *lock)
{
	return _remote_spin_trylock(&(lock->r_spinlock));
}
EXPORT_SYMBOL(_remote_mutex_trylock);
/* end remote mutex implementation ------------------------------------------ */