/*
* mv64x60_wdt.c - MV64X60 (Marvell Discovery) watchdog userspace interface
*
* Author: James Chapman <jchapman@katalix.com>
*
* Platform-specific setup code should configure the dog to generate
* interrupt or reset as required. This code only enables/disables
* and services the watchdog.
*
* Derived from mpc8xx_wdt.c, with the following copyright.
*
* 2002 (c) Florian Schirmer <jolt@tuxbox.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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/mv643xx.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#define MV64x60_WDT_WDC_OFFSET 0
/*
* The watchdog configuration register contains a pair of 2-bit fields,
* 1. a reload field, bits 27-26, which triggers a reload of
* the countdown register, and
* 2. an enable field, bits 25-24, which toggles between
* enabling and disabling the watchdog timer.
* Bit 31 is a read-only field which indicates whether the
* watchdog timer is currently enabled.
*
* The low 24 bits contain the timer reload value.
*/
#define MV64x60_WDC_ENABLE_SHIFT 24
#define MV64x60_WDC_SERVICE_SHIFT 26
#define MV64x60_WDC_ENABLED_SHIFT 31
#define MV64x60_WDC_ENABLED_TRUE 1
#define MV64x60_WDC_ENABLED_FALSE 0
/* Flags bits */
#define MV64x60_WDOG_FLAG_OPENED 0
static unsigned long wdt_flags;
static int wdt_status;
static void __iomem *mv64x60_wdt_regs;
static int mv64x60_wdt_timeout;
static int mv64x60_wdt_count;
static unsigned int bus_clk;
static char expect_close;
static DEFINE_SPINLOCK(mv64x60_wdt_spinlock);
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static int mv64x60_wdt_toggle_wdc(int enabled_predicate, int field_shift)
{
u32 data;
u32 enabled;
int ret = 0;
spin_lock(&mv64x60_wdt_spinlock);
data = readl(mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
enabled = (data >> MV64x60_WDC_ENABLED_SHIFT) & 1;
/* only toggle the requested field if enabled state matches predicate */
if ((enabled ^ enabled_predicate) == 0) {
/* We write a 1, then a 2 -- to the appropriate field */
data = (1 << field_shift) | mv64x60_wdt_count;
writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
data = (2 << field_shift) | mv64x60_wdt_count;
writel(data, mv64x60_wdt_regs + MV64x60_WDT_WDC_OFFSET);
ret = 1;
}
spin_unlock(&mv64x60_wdt_spinlock);
return ret;
}
static void mv64x60_wdt_service(void)
{
mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
MV64x60_WDC_SERVICE_SHIFT);
}
static void mv64x60_wdt_handler_enable(void)
{
if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_FALSE,
MV64x60_WDC_ENABLE_SHIFT)) {
mv64x60_wdt_service();
pr_notice("watchdog activated\n");
}
}
static void mv64x60_wdt_handler_disable(void)
{
if (mv64x60_wdt_toggle_wdc(MV64x60_WDC_ENABLED_TRUE,
MV64x60_WDC_ENABLE_SHIFT))
pr_notice("watchdog deactivated\n");
}
static void mv64x60_wdt_set_timeout(unsigned int timeout)
{
/* maximum bus cycle count is 0xFFFFFFFF */
if (timeout > 0xFFFFFFFF / bus_clk)
timeout = 0xFFFFFFFF / bus_clk;
mv64x60_wdt_count = timeout * bus_clk >> 8;
mv64x60_wdt_timeout = timeout;
}
static int mv64x60_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
mv64x60_wdt_handler_enable();
return nonseekable_open(inode, file);
}
static int mv64x60_wdt_release(struct inode *inode, struct file *file)
{
if (expect_close == 42)
mv64x60_wdt_handler_disable();
else {
pr_crit("unexpected close, not stopping timer!\n");
mv64x60_wdt_service();
}
expect_close = 0;
clear_bit(MV64x60_WDOG_FLAG_OPENED, &wdt_flags);
return 0;
}
static ssize_t mv64x60_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
if (len) {
if (!nowayout) {
size_t i;
expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
mv64x60_wdt_service();
}
return len;
}
static long mv64x60_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
int timeout;
int options;
void __user *argp = (void __user *)arg;
static const struct watchdog_info info = {
.options = WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.firmware_version = 0,
.identity = "MV64x60 watchdog",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &info, sizeof(info)))
return -EFAULT;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
if (put_user(wdt_status, (int __user *)argp))
return -EFAULT;
wdt_status &= ~WDIOF_KEEPALIVEPING;
break;
case WDIOC_GETTEMP:
return -EOPNOTSUPP;
case WDIOC_SETOPTIONS:
if (get_user(options, (int __user *)argp))
return -EFAULT;
if (options & WDIOS_DISABLECARD)
mv64x60_wdt_handler_disable();
if (options & WDIOS_ENABLECARD)
mv64x60_wdt_handler_enable();
break;
case WDIOC_KEEPALIVE:
mv64x60_wdt_service();
wdt_status |= WDIOF_KEEPALIVEPING;
break;
case WDIOC_SETTIMEOUT:
if (get_user(timeout, (int __user *)argp))
return -EFAULT;
mv64x60_wdt_set_timeout(timeout);
/* Fall through */
case WDIOC_GETTIMEOUT:
if (put_user(mv64x60_wdt_timeout, (int __user *)argp))
return -EFAULT;
break;
default:
return -ENOTTY;
}
return 0;
}
static const struct file_operations mv64x60_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = mv64x60_wdt_write,
.unlocked_ioctl = mv64x60_wdt_ioctl,
.open = mv64x60_wdt_open,
.release = mv64x60_wdt_release,
};
static struct miscdevice mv64x60_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &mv64x60_wdt_fops,
};
static int mv64x60_wdt_probe(struct platform_device *dev)
{
struct mv64x60_wdt_pdata *pdata = dev->dev.platform_data;
struct resource *r;
int timeout = 10;
bus_clk = 133; /* in MHz */
if (pdata) {
timeout = pdata->timeout;
bus_clk = pdata->bus_clk;
}
/* Since bus_clk is truncated MHz, actual frequency could be
* up to 1MHz higher. Round up, since it's better to time out
* too late than too soon.
*/
bus_clk++;
bus_clk *= 1000000; /* convert to Hz */
r = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (!r)
return -ENODEV;
mv64x60_wdt_regs = ioremap(r->start, resource_size(r));
if (mv64x60_wdt_regs == NULL)
return -ENOMEM;
mv64x60_wdt_set_timeout(timeout);
mv64x60_wdt_handler_disable(); /* in case timer was already running */
return misc_register(&mv64x60_wdt_miscdev);
}
static int mv64x60_wdt_remove(struct platform_device *dev)
{
misc_deregister(&mv64x60_wdt_miscdev);
mv64x60_wdt_handler_disable();
iounmap(mv64x60_wdt_regs);
return 0;
}
static struct platform_driver mv64x60_wdt_driver = {
.probe = mv64x60_wdt_probe,
.remove = mv64x60_wdt_remove,
.driver = {
.owner = THIS_MODULE,
.name = MV64x60_WDT_NAME,
},
};
static int __init mv64x60_wdt_init(void)
{
pr_info("MV64x60 watchdog driver\n");
return platform_driver_register(&mv64x60_wdt_driver);
}
static void __exit mv64x60_wdt_exit(void)
{
platform_driver_unregister(&mv64x60_wdt_driver);
}
module_init(mv64x60_wdt_init);
module_exit(mv64x60_wdt_exit);
MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("MV64x60 watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:" MV64x60_WDT_NAME);