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// SPDX-License-Identifier: GPL-2.0
/*
* OMAP hardware spinlock driver
*
* Copyright (C) 2010-2021 Texas Instruments Incorporated - https://www.ti.com
*
* Contact: Simon Que <sque@ti.com>
* Hari Kanigeri <h-kanigeri2@ti.com>
* Ohad Ben-Cohen <ohad@wizery.com>
* Suman Anna <s-anna@ti.com>
*/
#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/of.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_device *bank;
void __iomem *io_base;
int num_locks, i, ret;
/* Only a single hwspinlock block device is supported */
int base_id = 0;
io_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(io_base))
return PTR_ERR(io_base);
/*
* make sure the module is enabled and clocked before reading
* the module SYSSTATUS register
*/
devm_pm_runtime_enable(&pdev->dev);
ret = pm_runtime_resume_and_get(&pdev->dev);
if (ret < 0)
return ret;
/* Determine number of locks */
i = readl(io_base + SYSSTATUS_OFFSET);
i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
/*
* runtime PM will make sure the clock of this module is
* enabled again iff at least one lock is requested
*/
ret = pm_runtime_put(&pdev->dev);
if (ret < 0)
return ret;
/* one of the four lsb's must be set, and nothing else */
if (hweight_long(i & 0xf) != 1 || i > 8)
return -EINVAL;
num_locks = i * 32; /* actual number of locks in this device */
bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),
GFP_KERNEL);
if (!bank)
return -ENOMEM;
for (i = 0; i < num_locks; i++)
bank->lock[i].priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
return devm_hwspin_lock_register(&pdev->dev, bank, &omap_hwspinlock_ops,
base_id, num_locks);
}
static const struct of_device_id omap_hwspinlock_of_match[] = {
{ .compatible = "ti,omap4-hwspinlock", },
{ .compatible = "ti,am64-hwspinlock", },
{ .compatible = "ti,am654-hwspinlock", },
{ /* end */ },
};
MODULE_DEVICE_TABLE(of, omap_hwspinlock_of_match);
static struct platform_driver omap_hwspinlock_driver = {
.probe = omap_hwspinlock_probe,
.driver = {
.name = "omap_hwspinlock",
.of_match_table = omap_hwspinlock_of_match,
},
};
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>");
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