/*
* drivers/char/watchdog/max63xx_wdt.c
*
* Driver for max63{69,70,71,72,73,74} watchdog timers
*
* Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*
* This driver assumes the watchdog pins are memory mapped (as it is
* the case for the Arcom Zeus). Should it be connected over GPIOs or
* another interface, some abstraction will have to be introduced.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/device.h>
#define DEFAULT_HEARTBEAT 60
#define MAX_HEARTBEAT 60
static int heartbeat = DEFAULT_HEARTBEAT;
static int nowayout = WATCHDOG_NOWAYOUT;
/*
* Memory mapping: a single byte, 3 first lower bits to select bit 3
* to ping the watchdog.
*/
#define MAX6369_WDSET (7 << 0)
#define MAX6369_WDI (1 << 3)
static DEFINE_SPINLOCK(io_lock);
static unsigned long wdt_status;
#define WDT_IN_USE 0
#define WDT_RUNNING 1
#define WDT_OK_TO_CLOSE 2
static int nodelay;
static struct resource *wdt_mem;
static void __iomem *wdt_base;
static struct platform_device *max63xx_pdev;
/*
* The timeout values used are actually the absolute minimum the chip
* offers. Typical values on my board are slightly over twice as long
* (10s setting ends up with a 25s timeout), and can be up to 3 times
* the nominal setting (according to the datasheet). So please take
* these values with a grain of salt. Same goes for the initial delay
* "feature". Only max6373/74 have a few settings without this initial
* delay (selected with the "nodelay" parameter).
*
* I also decided to remove from the tables any timeout smaller than a
* second, as it looked completly overkill...
*/
/* Timeouts in second */
struct max63xx_timeout {
u8 wdset;
u8 tdelay;
u8 twd;
};
static struct max63xx_timeout max6369_table[] = {
{ 5, 1, 1 },
{ 6, 10, 10 },
{ 7, 60, 60 },
{ },
};
static struct max63xx_timeout max6371_table[] = {
{ 6, 60, 3 },
{ 7, 60, 60 },
{ },
};
static struct max63xx_timeout max6373_table[] = {
{ 2, 60, 1 },
{ 5, 0, 1 },
{ 1, 3, 3 },
{ 7, 60, 10 },
{ 6, 0, 10 },
{ },
};
static struct max63xx_timeout *current_timeout;
static struct max63xx_timeout *
max63xx_select_timeout(struct max63xx_timeout *table, int value)
{
while (table->twd) {
if (value <= table->twd) {
if (nodelay && table->tdelay == 0)
return table;
if (!nodelay)
return table;
}
table++;
}
return NULL;
}
static void max63xx_wdt_ping(void)
{
u8 val;
spin_lock(&io_lock);
val = __raw_readb(wdt_base);
__raw_writeb(val | MAX6369_WDI, wdt_base);
__raw_writeb(val & ~MAX6369_WDI, wdt_base);
spin_unlock(&io_lock);
}
static void max63xx_wdt_enable(struct max63xx_timeout *entry)
{
u8 val;
if (test_and_set_bit(WDT_RUNNING, &wdt_status))
return;
spin_lock(&io_lock);
val = __raw_readb(wdt_base);
val &= ~MAX6369_WDSET;
val |= entry->wdset;
__raw_writeb(val, wdt_base);
spin_unlock(&io_lock);
/* check for a edge triggered startup */
if (entry->tdelay == 0)
max63xx_wdt_ping();
}
static void max63xx_wdt_disable(void)
{
spin_lock(&io_lock);
__raw_writeb(3, wdt_base);
spin_unlock(&io_lock);
clear_bit(WDT_RUNNING, &wdt_status);
}
static int max63xx_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(WDT_IN_USE, &wdt_status))
return -EBUSY;
max63xx_wdt_enable(current_timeout);
clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
return nonseekable_open(inode, file);
}
static ssize_t max63xx_wdt_write(struct file *file, const char *data,
size_t len, loff_t *ppos)
{
if (len) {
if (!nowayout) {
size_t i;
clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
set_bit(WDT_OK_TO_CLOSE, &wdt_status);
}
}
max63xx_wdt_ping();
}
return len;
}
static const struct watchdog_info ident = {
.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
.identity = "max63xx Watchdog",
};
static long max63xx_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int ret = -ENOTTY;
switch (cmd) {
case WDIOC_GETSUPPORT:
ret = copy_to_user((struct watchdog_info *)arg, &ident,
sizeof(ident)) ? -EFAULT : 0;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
ret = put_user(0, (int *)arg);
break;
case WDIOC_KEEPALIVE:
max63xx_wdt_ping();
ret = 0;
break;
case WDIOC_GETTIMEOUT:
ret = put_user(heartbeat, (int *)arg);
break;
}
return ret;
}
static int max63xx_wdt_release(struct inode *inode, struct file *file)
{
if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
max63xx_wdt_disable();
else
dev_crit(&max63xx_pdev->dev,
"device closed unexpectedly - timer will not stop\n");
clear_bit(WDT_IN_USE, &wdt_status);
clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
return 0;
}
static const struct file_operations max63xx_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = max63xx_wdt_write,
.unlocked_ioctl = max63xx_wdt_ioctl,
.open = max63xx_wdt_open,
.release = max63xx_wdt_release,
};
static struct miscdevice max63xx_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &max63xx_wdt_fops,
};
static int __devinit max63xx_wdt_probe(struct platform_device *pdev)
{
int ret = 0;
int size;
struct resource *res;
struct device *dev = &pdev->dev;
struct max63xx_timeout *table;
table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
heartbeat = DEFAULT_HEARTBEAT;
dev_info(dev, "requesting %ds heartbeat\n", heartbeat);
current_timeout = max63xx_select_timeout(table, heartbeat);
if (!current_timeout) {
dev_err(dev, "unable to satisfy heartbeat request\n");
return -EINVAL;
}
dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
current_timeout->twd, current_timeout->tdelay);
heartbeat = current_timeout->twd;
max63xx_pdev = pdev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res == NULL) {
dev_err(dev, "failed to get memory region resource\n");
return -ENOENT;
}
size = resource_size(res);
wdt_mem = request_mem_region(res->start, size, pdev->name);
if (wdt_mem == NULL) {
dev_err(dev, "failed to get memory region\n");
return -ENOENT;
}
wdt_base = ioremap(res->start, size);
if (!wdt_base) {
dev_err(dev, "failed to map memory region\n");
ret = -ENOMEM;
goto out_request;
}
ret = misc_register(&max63xx_wdt_miscdev);
if (ret < 0) {
dev_err(dev, "cannot register misc device\n");
goto out_unmap;
}
return 0;
out_unmap:
iounmap(wdt_base);
out_request:
release_resource(wdt_mem);
kfree(wdt_mem);
return ret;
}
static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
{
misc_deregister(&max63xx_wdt_miscdev);
if (wdt_mem) {
release_resource(wdt_mem);
kfree(wdt_mem);
wdt_mem = NULL;
}
if (wdt_base)
iounmap(wdt_base);
return 0;
}
static struct platform_device_id max63xx_id_table[] = {
{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
{ },
};
MODULE_DEVICE_TABLE(platform, max63xx_id_table);
static struct platform_driver max63xx_wdt_driver = {
.probe = max63xx_wdt_probe,
.remove = __devexit_p(max63xx_wdt_remove),
.id_table = max63xx_id_table,
.driver = {
.name = "max63xx_wdt",
.owner = THIS_MODULE,
},
};
static int __init max63xx_wdt_init(void)
{
return platform_driver_register(&max63xx_wdt_driver);
}
static void __exit max63xx_wdt_exit(void)
{
platform_driver_unregister(&max63xx_wdt_driver);
}
module_init(max63xx_wdt_init);
module_exit(max63xx_wdt_exit);
MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
MODULE_DESCRIPTION("max63xx Watchdog Driver");
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
"Watchdog heartbeat period in seconds from 1 to "
__MODULE_STRING(MAX_HEARTBEAT) ", default "
__MODULE_STRING(DEFAULT_HEARTBEAT));
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
module_param(nodelay, int, 0);
MODULE_PARM_DESC(nodelay,
"Force selection of a timeout setting without initial delay "
"(max6373/74 only, default=0)");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
