omap_hwspinlock.c
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/*
* OMAP hardware spinlock driver
*
* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
*
* Contact: Simon Que <sque@ti.com>
* Hari Kanigeri <h-kanigeri2@ti.com>
* Ohad Ben-Cohen <ohad@wizery.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* 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/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/bitops.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/hwspinlock.h>
#include <linux/platform_device.h>
#include "hwspinlock_internal.h"
/* Spinlock register offsets */
#define SYSSTATUS_OFFSET 0x0014
#define LOCK_BASE_OFFSET 0x0800
#define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
/* Possible values of SPINLOCK_LOCK_REG */
#define SPINLOCK_NOTTAKEN (0) /* free */
#define SPINLOCK_TAKEN (1) /* locked */
static int omap_hwspinlock_trylock(struct hwspinlock *lock)
{
void __iomem *lock_addr = lock->priv;
/* attempt to acquire the lock by reading its value */
return (SPINLOCK_NOTTAKEN == readl(lock_addr));
}
static void omap_hwspinlock_unlock(struct hwspinlock *lock)
{
void __iomem *lock_addr = lock->priv;
/* release the lock by writing 0 to it */
writel(SPINLOCK_NOTTAKEN, lock_addr);
}
/*
* relax the OMAP interconnect while spinning on it.
*
* The specs recommended that the retry delay time will be
* just over half of the time that a requester would be
* expected to hold the lock.
*
* The number below is taken from an hardware specs example,
* obviously it is somewhat arbitrary.
*/
static void omap_hwspinlock_relax(struct hwspinlock *lock)
{
ndelay(50);
}
static const struct hwspinlock_ops omap_hwspinlock_ops = {
.trylock = omap_hwspinlock_trylock,
.unlock = omap_hwspinlock_unlock,
.relax = omap_hwspinlock_relax,
};
static int omap_hwspinlock_probe(struct platform_device *pdev)
{
struct hwspinlock_pdata *pdata = pdev->dev.platform_data;
struct hwspinlock_device *bank;
struct hwspinlock *hwlock;
struct resource *res;
void __iomem *io_base;
int num_locks, i, ret;
if (!pdata)
return -ENODEV;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENODEV;
io_base = ioremap(res->start, resource_size(res));
if (!io_base)
return -ENOMEM;
/* Determine number of locks */
i = readl(io_base + SYSSTATUS_OFFSET);
i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
/* one of the four lsb's must be set, and nothing else */
if (hweight_long(i & 0xf) != 1 || i > 8) {
ret = -EINVAL;
goto iounmap_base;
}
num_locks = i * 32; /* actual number of locks in this device */
bank = kzalloc(sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL);
if (!bank) {
ret = -ENOMEM;
goto iounmap_base;
}
platform_set_drvdata(pdev, bank);
for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
/*
* runtime PM will make sure the clock of this module is
* enabled iff at least one lock is requested
*/
pm_runtime_enable(&pdev->dev);
ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops,
pdata->base_id, num_locks);
if (ret)
goto reg_fail;
return 0;
reg_fail:
pm_runtime_disable(&pdev->dev);
kfree(bank);
iounmap_base:
iounmap(io_base);
return ret;
}
static int omap_hwspinlock_remove(struct platform_device *pdev)
{
struct hwspinlock_device *bank = platform_get_drvdata(pdev);
void __iomem *io_base = bank->lock[0].priv - LOCK_BASE_OFFSET;
int ret;
ret = hwspin_lock_unregister(bank);
if (ret) {
dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
return ret;
}
pm_runtime_disable(&pdev->dev);
iounmap(io_base);
kfree(bank);
return 0;
}
static struct platform_driver omap_hwspinlock_driver = {
.probe = omap_hwspinlock_probe,
.remove = omap_hwspinlock_remove,
.driver = {
.name = "omap_hwspinlock",
.owner = THIS_MODULE,
},
};
static int __init omap_hwspinlock_init(void)
{
return platform_driver_register(&omap_hwspinlock_driver);
}
/* board init code might need to reserve hwspinlocks for predefined purposes */
postcore_initcall(omap_hwspinlock_init);
static void __exit omap_hwspinlock_exit(void)
{
platform_driver_unregister(&omap_hwspinlock_driver);
}
module_exit(omap_hwspinlock_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
MODULE_AUTHOR("Simon Que <sque@ti.com>");
MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");