/*
* drivers/char/watchdog/sp805-wdt.c
*
* Watchdog driver for ARM SP805 watchdog module
*
* Copyright (C) 2010 ST Microelectronics
* Viresh Kumar <viresh.linux@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2 or later. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/device.h>
#include <linux/resource.h>
#include <linux/amba/bus.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/watchdog.h>
/* default timeout in seconds */
#define DEFAULT_TIMEOUT 60
#define MODULE_NAME "sp805-wdt"
/* watchdog register offsets and masks */
#define WDTLOAD 0x000
#define LOAD_MIN 0x00000001
#define LOAD_MAX 0xFFFFFFFF
#define WDTVALUE 0x004
#define WDTCONTROL 0x008
/* control register masks */
#define INT_ENABLE (1 << 0)
#define RESET_ENABLE (1 << 1)
#define WDTINTCLR 0x00C
#define WDTRIS 0x010
#define WDTMIS 0x014
#define INT_MASK (1 << 0)
#define WDTLOCK 0xC00
#define UNLOCK 0x1ACCE551
#define LOCK 0x00000001
/**
* struct sp805_wdt: sp805 wdt device structure
* @wdd: instance of struct watchdog_device
* @lock: spin lock protecting dev structure and io access
* @base: base address of wdt
* @clk: clock structure of wdt
* @adev: amba device structure of wdt
* @status: current status of wdt
* @load_val: load value to be set for current timeout
* @timeout: current programmed timeout
*/
struct sp805_wdt {
struct watchdog_device wdd;
spinlock_t lock;
void __iomem *base;
struct clk *clk;
struct amba_device *adev;
unsigned int load_val;
unsigned int timeout;
};
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Set to 1 to keep watchdog running after device release");
/* This routine finds load value that will reset system in required timout */
static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
{
struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
u64 load, rate;
rate = clk_get_rate(wdt->clk);
/*
* sp805 runs counter with given value twice, after the end of first
* counter it gives an interrupt and then starts counter again. If
* interrupt already occurred then it resets the system. This is why
* load is half of what should be required.
*/
load = div_u64(rate, 2) * timeout - 1;
load = (load > LOAD_MAX) ? LOAD_MAX : load;
load = (load < LOAD_MIN) ? LOAD_MIN : load;
spin_lock(&wdt->lock);
wdt->load_val = load;
/* roundup timeout to closest positive integer value */
wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
spin_unlock(&wdt->lock);
return 0;
}
/* returns number of seconds left for reset to occur */
static unsigned int wdt_timeleft(struct watchdog_device *wdd)
{
struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
u64 load, rate;
rate = clk_get_rate(wdt->clk);
spin_lock(&wdt->lock);
load = readl_relaxed(wdt->base + WDTVALUE);
/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
load += wdt->load_val + 1;
spin_unlock(&wdt->lock);
return div_u64(load, rate);
}
static int wdt_config(struct watchdog_device *wdd, bool ping)
{
struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
int ret;
if (!ping) {
ret = clk_prepare_enable(wdt->clk);
if (ret) {
dev_err(&wdt->adev->dev, "clock enable fail");
return ret;
}
}
spin_lock(&wdt->lock);
writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
if (!ping) {
writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
WDTCONTROL);
}
writel_relaxed(LOCK, wdt->base + WDTLOCK);
/* Flush posted writes. */
readl_relaxed(wdt->base + WDTLOCK);
spin_unlock(&wdt->lock);
return 0;
}
static int wdt_ping(struct watchdog_device *wdd)
{
return wdt_config(wdd, true);
}
/* enables watchdog timers reset */
static int wdt_enable(struct watchdog_device *wdd)
{
return wdt_config(wdd, false);
}
/* disables watchdog timers reset */
static int wdt_disable(struct watchdog_device *wdd)
{
struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
spin_lock(&wdt->lock);
writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
writel_relaxed(0, wdt->base + WDTCONTROL);
writel_relaxed(LOCK, wdt->base + WDTLOCK);
/* Flush posted writes. */
readl_relaxed(wdt->base + WDTLOCK);
spin_unlock(&wdt->lock);
clk_disable_unprepare(wdt->clk);
return 0;
}
static const struct watchdog_info wdt_info = {
.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
.identity = MODULE_NAME,
};
static const struct watchdog_ops wdt_ops = {
.owner = THIS_MODULE,
.start = wdt_enable,
.stop = wdt_disable,
.ping = wdt_ping,
.set_timeout = wdt_setload,
.get_timeleft = wdt_timeleft,
};
static int
sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
{
struct sp805_wdt *wdt;
int ret = 0;
if (!devm_request_mem_region(&adev->dev, adev->res.start,
resource_size(&adev->res), "sp805_wdt")) {
dev_warn(&adev->dev, "Failed to get memory region resource\n");
ret = -ENOENT;
goto err;
}
wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
if (!wdt) {
dev_warn(&adev->dev, "Kzalloc failed\n");
ret = -ENOMEM;
goto err;
}
wdt->base = devm_ioremap(&adev->dev, adev->res.start,
resource_size(&adev->res));
if (!wdt->base) {
ret = -ENOMEM;
dev_warn(&adev->dev, "ioremap fail\n");
goto err;
}
wdt->clk = devm_clk_get(&adev->dev, NULL);
if (IS_ERR(wdt->clk)) {
dev_warn(&adev->dev, "Clock not found\n");
ret = PTR_ERR(wdt->clk);
goto err;
}
wdt->adev = adev;
wdt->wdd.info = &wdt_info;
wdt->wdd.ops = &wdt_ops;
spin_lock_init(&wdt->lock);
watchdog_set_nowayout(&wdt->wdd, nowayout);
watchdog_set_drvdata(&wdt->wdd, wdt);
wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
ret = watchdog_register_device(&wdt->wdd);
if (ret) {
dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
ret);
goto err;
}
amba_set_drvdata(adev, wdt);
dev_info(&adev->dev, "registration successful\n");
return 0;
err:
dev_err(&adev->dev, "Probe Failed!!!\n");
return ret;
}
static int sp805_wdt_remove(struct amba_device *adev)
{
struct sp805_wdt *wdt = amba_get_drvdata(adev);
watchdog_unregister_device(&wdt->wdd);
watchdog_set_drvdata(&wdt->wdd, NULL);
return 0;
}
static int __maybe_unused sp805_wdt_suspend(struct device *dev)
{
struct sp805_wdt *wdt = dev_get_drvdata(dev);
if (watchdog_active(&wdt->wdd))
return wdt_disable(&wdt->wdd);
return 0;
}
static int __maybe_unused sp805_wdt_resume(struct device *dev)
{
struct sp805_wdt *wdt = dev_get_drvdata(dev);
if (watchdog_active(&wdt->wdd))
return wdt_enable(&wdt->wdd);
return 0;
}
static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
sp805_wdt_resume);
static struct amba_id sp805_wdt_ids[] = {
{
.id = 0x00141805,
.mask = 0x00ffffff,
},
{ 0, 0 },
};
MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
static struct amba_driver sp805_wdt_driver = {
.drv = {
.name = MODULE_NAME,
.pm = &sp805_wdt_dev_pm_ops,
},
.id_table = sp805_wdt_ids,
.probe = sp805_wdt_probe,
.remove = sp805_wdt_remove,
};
module_amba_driver(sp805_wdt_driver);
MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
MODULE_LICENSE("GPL");
