u8500_hsem.c
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/*
* u8500 HWSEM driver
*
* Copyright (C) 2010-2011 ST-Ericsson
*
* Implements u8500 semaphore handling for protocol 1, no interrupts.
*
* Author: Mathieu Poirier <mathieu.poirier@linaro.org>
* Heavily borrowed from the work of :
* 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/module.h>
#include <linux/delay.h>
#include <linux/io.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"
/*
* Implementation of STE's HSem protocol 1 without interrutps.
* The only masterID we allow is '0x01' to force people to use
* HSems for synchronisation between processors rather than processes
* on the ARM core.
*/
#define U8500_MAX_SEMAPHORE 32 /* a total of 32 semaphore */
#define RESET_SEMAPHORE (0) /* free */
/*
* CPU ID for master running u8500 kernel.
* Hswpinlocks should only be used to synchonise operations
* between the Cortex A9 core and the other CPUs. Hence
* forcing the masterID to a preset value.
*/
#define HSEM_MASTER_ID 0x01
#define HSEM_REGISTER_OFFSET 0x08
#define HSEM_CTRL_REG 0x00
#define HSEM_ICRALL 0x90
#define HSEM_PROTOCOL_1 0x01
static int u8500_hsem_trylock(struct hwspinlock *lock)
{
void __iomem *lock_addr = lock->priv;
writel(HSEM_MASTER_ID, lock_addr);
/* get only first 4 bit and compare to masterID.
* if equal, we have the semaphore, otherwise
* someone else has it.
*/
return (HSEM_MASTER_ID == (0x0F & readl(lock_addr)));
}
static void u8500_hsem_unlock(struct hwspinlock *lock)
{
void __iomem *lock_addr = lock->priv;
/* release the lock by writing 0 to it */
writel(RESET_SEMAPHORE, lock_addr);
}
/*
* u8500: what value is recommended here ?
*/
static void u8500_hsem_relax(struct hwspinlock *lock)
{
ndelay(50);
}
static const struct hwspinlock_ops u8500_hwspinlock_ops = {
.trylock = u8500_hsem_trylock,
.unlock = u8500_hsem_unlock,
.relax = u8500_hsem_relax,
};
static int u8500_hsem_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 i, ret, num_locks = U8500_MAX_SEMAPHORE;
ulong val;
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;
/* make sure protocol 1 is selected */
val = readl(io_base + HSEM_CTRL_REG);
writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG);
/* clear all interrupts */
writel(0xFFFF, io_base + HSEM_ICRALL);
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 + HSEM_REGISTER_OFFSET + sizeof(u32) * i;
/* no pm needed for HSem but required to comply with hwspilock core */
pm_runtime_enable(&pdev->dev);
ret = hwspin_lock_register(bank, &pdev->dev, &u8500_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 u8500_hsem_remove(struct platform_device *pdev)
{
struct hwspinlock_device *bank = platform_get_drvdata(pdev);
void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET;
int ret;
/* clear all interrupts */
writel(0xFFFF, io_base + HSEM_ICRALL);
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 u8500_hsem_driver = {
.probe = u8500_hsem_probe,
.remove = u8500_hsem_remove,
.driver = {
.name = "u8500_hsem",
},
};
static int __init u8500_hsem_init(void)
{
return platform_driver_register(&u8500_hsem_driver);
}
/* board init code might need to reserve hwspinlocks for predefined purposes */
postcore_initcall(u8500_hsem_init);
static void __exit u8500_hsem_exit(void)
{
platform_driver_unregister(&u8500_hsem_driver);
}
module_exit(u8500_hsem_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Hardware Spinlock driver for u8500");
MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");