/*
* drivers/char/watchdog/sp805-wdt.c
*
* Watchdog driver for ARM SP805 watchdog module
*
* Copyright (C) 2010 ST Microelectronics
* Viresh Kumar<viresh.kumar@st.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/fs.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/uaccess.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
*
* lock: spin lock protecting dev structure and io access
* base: base address of wdt
* clk: clock structure of wdt
* dev: 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 {
spinlock_t lock;
void __iomem *base;
struct clk *clk;
struct amba_device *adev;
unsigned long status;
#define WDT_BUSY 0
#define WDT_CAN_BE_CLOSED 1
unsigned int load_val;
unsigned int timeout;
};
/* local variables */
static struct sp805_wdt *wdt;
static int nowayout = WATCHDOG_NOWAYOUT;
/* This routine finds load value that will reset system in required timout */
static void wdt_setload(unsigned int timeout)
{
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);
}
/* returns number of seconds left for reset to occur */
static u32 wdt_timeleft(void)
{
u64 load, rate;
rate = clk_get_rate(wdt->clk);
spin_lock(&wdt->lock);
load = readl(wdt->base + WDTVALUE);
/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
if (!(readl(wdt->base + WDTRIS) & INT_MASK))
load += wdt->load_val + 1;
spin_unlock(&wdt->lock);
return div_u64(load, rate);
}
/* enables watchdog timers reset */
static void wdt_enable(void)
{
spin_lock(&wdt->lock);
writel(UNLOCK, wdt->base + WDTLOCK);
writel(wdt->load_val, wdt->base + WDTLOAD);
writel(INT_MASK, wdt->base + WDTINTCLR);
writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
writel(LOCK, wdt->base + WDTLOCK);
spin_unlock(&wdt->lock);
}
/* disables watchdog timers reset */
static void wdt_disable(void)
{
spin_lock(&wdt->lock);
writel(UNLOCK, wdt->base + WDTLOCK);
writel(0, wdt->base + WDTCONTROL);
writel(0, wdt->base + WDTLOAD);
writel(LOCK, wdt->base + WDTLOCK);
spin_unlock(&wdt->lock);
}
static ssize_t sp805_wdt_write(struct file *file, const char *data,
size_t len, loff_t *ppos)
{
if (len) {
if (!nowayout) {
size_t i;
clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
/* Check for Magic Close character */
if (c == 'V') {
set_bit(WDT_CAN_BE_CLOSED,
&wdt->status);
break;
}
}
}
wdt_enable();
}
return len;
}
static const struct watchdog_info ident = {
.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
.identity = MODULE_NAME,
};
static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret = -ENOTTY;
unsigned int timeout;
switch (cmd) {
case WDIOC_GETSUPPORT:
ret = copy_to_user((struct watchdog_info *)arg, &ident,
sizeof(ident)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
ret = put_user(0, (int *)arg);
break;
case WDIOC_KEEPALIVE:
wdt_enable();
ret = 0;
break;
case WDIOC_SETTIMEOUT:
ret = get_user(timeout, (unsigned int *)arg);
if (ret)
break;
wdt_setload(timeout);
wdt_enable();
/* Fall through */
case WDIOC_GETTIMEOUT:
ret = put_user(wdt->timeout, (unsigned int *)arg);
break;
case WDIOC_GETTIMELEFT:
ret = put_user(wdt_timeleft(), (unsigned int *)arg);
break;
}
return ret;
}
static int sp805_wdt_open(struct inode *inode, struct file *file)
{
int ret = 0;
if (test_and_set_bit(WDT_BUSY, &wdt->status))
return -EBUSY;
ret = clk_enable(wdt->clk);
if (ret) {
dev_err(&wdt->adev->dev, "clock enable fail");
goto err;
}
wdt_enable();
/* can not be closed, once enabled */
clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
return nonseekable_open(inode, file);
err:
clear_bit(WDT_BUSY, &wdt->status);
return ret;
}
static int sp805_wdt_release(struct inode *inode, struct file *file)
{
if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
clear_bit(WDT_BUSY, &wdt->status);
dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
return 0;
}
wdt_disable();
clk_disable(wdt->clk);
clear_bit(WDT_BUSY, &wdt->status);
return 0;
}
static const struct file_operations sp805_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = sp805_wdt_write,
.unlocked_ioctl = sp805_wdt_ioctl,
.open = sp805_wdt_open,
.release = sp805_wdt_release,
};
static struct miscdevice sp805_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &sp805_wdt_fops,
};
static int __devinit
sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
{
int ret = 0;
if (!request_mem_region(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 = kzalloc(sizeof(*wdt), GFP_KERNEL);
if (!wdt) {
dev_warn(&adev->dev, "Kzalloc failed\n");
ret = -ENOMEM;
goto err_kzalloc;
}
wdt->clk = 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_clk_get;
}
wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
if (!wdt->base) {
ret = -ENOMEM;
dev_warn(&adev->dev, "ioremap fail\n");
goto err_ioremap;
}
wdt->adev = adev;
spin_lock_init(&wdt->lock);
wdt_setload(DEFAULT_TIMEOUT);
ret = misc_register(&sp805_wdt_miscdev);
if (ret < 0) {
dev_warn(&adev->dev, "cannot register misc device\n");
goto err_misc_register;
}
dev_info(&adev->dev, "registration successful\n");
return 0;
err_misc_register:
iounmap(wdt->base);
err_ioremap:
clk_put(wdt->clk);
err_clk_get:
kfree(wdt);
wdt = NULL;
err_kzalloc:
release_mem_region(adev->res.start, resource_size(&adev->res));
err:
dev_err(&adev->dev, "Probe Failed!!!\n");
return ret;
}
static int __devexit sp805_wdt_remove(struct amba_device *adev)
{
misc_deregister(&sp805_wdt_miscdev);
iounmap(wdt->base);
clk_put(wdt->clk);
kfree(wdt);
release_mem_region(adev->res.start, resource_size(&adev->res));
return 0;
}
static struct amba_id sp805_wdt_ids[] __initdata = {
{
.id = 0x00141805,
.mask = 0x00ffffff,
},
{ 0, 0 },
};
static struct amba_driver sp805_wdt_driver = {
.drv = {
.name = MODULE_NAME,
},
.id_table = sp805_wdt_ids,
.probe = sp805_wdt_probe,
.remove = __devexit_p(sp805_wdt_remove),
};
static int __init sp805_wdt_init(void)
{
return amba_driver_register(&sp805_wdt_driver);
}
module_init(sp805_wdt_init);
static void __exit sp805_wdt_exit(void)
{
amba_driver_unregister(&sp805_wdt_driver);
}
module_exit(sp805_wdt_exit);
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
"Set to 1 to keep watchdog running after device release");
MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
