/*
* of_xilinx_wdt.c 1.01 A Watchdog Device Driver for Xilinx xps_timebase_wdt
*
* (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>)
*
* -----------------------
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* -----------------------
* 30-May-2011 Alejandro Cabrera <aldaya@gmail.com>
* - If "xlnx,wdt-enable-once" wasn't found on device tree the
* module will use CONFIG_WATCHDOG_NOWAYOUT
* - If the device tree parameters ("clock-frequency" and
* "xlnx,wdt-interval") wasn't found the driver won't
* know the wdt reset interval
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_address.h>
/* Register offsets for the Wdt device */
#define XWT_TWCSR0_OFFSET 0x0 /* Control/Status Register0 */
#define XWT_TWCSR1_OFFSET 0x4 /* Control/Status Register1 */
#define XWT_TBR_OFFSET 0x8 /* Timebase Register Offset */
/* Control/Status Register Masks */
#define XWT_CSR0_WRS_MASK 0x00000008 /* Reset status */
#define XWT_CSR0_WDS_MASK 0x00000004 /* Timer state */
#define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
/* Control/Status Register 0/1 bits */
#define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
/* SelfTest constants */
#define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
#define XWT_TIMER_FAILED 0xFFFFFFFF
#define WATCHDOG_NAME "Xilinx Watchdog"
#define PFX WATCHDOG_NAME ": "
struct xwdt_device {
struct resource res;
void __iomem *base;
u32 nowayout;
u32 wdt_interval;
u32 boot_status;
};
static struct xwdt_device xdev;
static u32 timeout;
static u32 control_status_reg;
static u8 expect_close;
static u8 no_timeout;
static unsigned long driver_open;
static DEFINE_SPINLOCK(spinlock);
static void xwdt_start(void)
{
spin_lock(&spinlock);
/* Clean previous status and enable the watchdog timer */
control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
xdev.base + XWT_TWCSR0_OFFSET);
iowrite32(XWT_CSRX_EWDT2_MASK, xdev.base + XWT_TWCSR1_OFFSET);
spin_unlock(&spinlock);
}
static void xwdt_stop(void)
{
spin_lock(&spinlock);
control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
xdev.base + XWT_TWCSR0_OFFSET);
iowrite32(0, xdev.base + XWT_TWCSR1_OFFSET);
spin_unlock(&spinlock);
printk(KERN_INFO PFX "Stopped!\n");
}
static void xwdt_keepalive(void)
{
spin_lock(&spinlock);
control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
iowrite32(control_status_reg, xdev.base + XWT_TWCSR0_OFFSET);
spin_unlock(&spinlock);
}
static void xwdt_get_status(int *status)
{
int new_status;
spin_lock(&spinlock);
control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
new_status = ((control_status_reg &
(XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK)) != 0);
spin_unlock(&spinlock);
*status = 0;
if (new_status & 1)
*status |= WDIOF_CARDRESET;
}
static u32 xwdt_selftest(void)
{
int i;
u32 timer_value1;
u32 timer_value2;
spin_lock(&spinlock);
timer_value1 = ioread32(xdev.base + XWT_TBR_OFFSET);
timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
for (i = 0;
((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
(timer_value2 == timer_value1)); i++) {
timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
}
spin_unlock(&spinlock);
if (timer_value2 != timer_value1)
return ~XWT_TIMER_FAILED;
else
return XWT_TIMER_FAILED;
}
static int xwdt_open(struct inode *inode, struct file *file)
{
/* Only one process can handle the wdt at a time */
if (test_and_set_bit(0, &driver_open))
return -EBUSY;
/* Make sure that the module are always loaded...*/
if (xdev.nowayout)
__module_get(THIS_MODULE);
xwdt_start();
printk(KERN_INFO PFX "Started...\n");
return nonseekable_open(inode, file);
}
static int xwdt_release(struct inode *inode, struct file *file)
{
if (expect_close == 42) {
xwdt_stop();
} else {
printk(KERN_CRIT PFX
"Unexpected close, not stopping watchdog!\n");
xwdt_keepalive();
}
clear_bit(0, &driver_open);
expect_close = 0;
return 0;
}
/*
* xwdt_write:
* @file: file handle to the watchdog
* @buf: buffer to write (unused as data does not matter here
* @count: count of bytes
* @ppos: pointer to the position to write. No seeks allowed
*
* A write to a watchdog device is defined as a keepalive signal. Any
* write of data will do, as we don't define content meaning.
*/
static ssize_t xwdt_write(struct file *file, const char __user *buf,
size_t len, loff_t *ppos)
{
if (len) {
if (!xdev.nowayout) {
size_t i;
/* In case it was set long ago */
expect_close = 0;
for (i = 0; i != len; i++) {
char c;
if (get_user(c, buf + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
xwdt_keepalive();
}
return len;
}
static const struct watchdog_info ident = {
.options = WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.firmware_version = 1,
.identity = WATCHDOG_NAME,
};
/*
* xwdt_ioctl:
* @file: file handle to the device
* @cmd: watchdog command
* @arg: argument pointer
*
* The watchdog API defines a common set of functions for all watchdogs
* according to their available features.
*/
static long xwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int status;
union {
struct watchdog_info __user *ident;
int __user *i;
} uarg;
uarg.i = (int __user *)arg;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(uarg.ident, &ident,
sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETBOOTSTATUS:
return put_user(xdev.boot_status, uarg.i);
case WDIOC_GETSTATUS:
xwdt_get_status(&status);
return put_user(status, uarg.i);
case WDIOC_KEEPALIVE:
xwdt_keepalive();
return 0;
case WDIOC_GETTIMEOUT:
if (no_timeout)
return -ENOTTY;
else
return put_user(timeout, uarg.i);
default:
return -ENOTTY;
}
}
static const struct file_operations xwdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = xwdt_write,
.open = xwdt_open,
.release = xwdt_release,
.unlocked_ioctl = xwdt_ioctl,
};
static struct miscdevice xwdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &xwdt_fops,
};
static int __devinit xwdt_probe(struct platform_device *pdev)
{
int rc;
u32 *tmptr;
u32 *pfreq;
no_timeout = 0;
pfreq = (u32 *)of_get_property(pdev->dev.of_node->parent,
"clock-frequency", NULL);
if (pfreq == NULL) {
printk(KERN_WARNING PFX
"The watchdog clock frequency cannot be obtained!\n");
no_timeout = 1;
}
rc = of_address_to_resource(pdev->dev.of_node, 0, &xdev.res);
if (rc) {
printk(KERN_WARNING PFX "invalid address!\n");
return rc;
}
tmptr = (u32 *)of_get_property(pdev->dev.of_node,
"xlnx,wdt-interval", NULL);
if (tmptr == NULL) {
printk(KERN_WARNING PFX "Parameter \"xlnx,wdt-interval\""
" not found in device tree!\n");
no_timeout = 1;
} else {
xdev.wdt_interval = *tmptr;
}
tmptr = (u32 *)of_get_property(pdev->dev.of_node,
"xlnx,wdt-enable-once", NULL);
if (tmptr == NULL) {
printk(KERN_WARNING PFX "Parameter \"xlnx,wdt-enable-once\""
" not found in device tree!\n");
xdev.nowayout = WATCHDOG_NOWAYOUT;
}
/*
* Twice of the 2^wdt_interval / freq because the first wdt overflow is
* ignored (interrupt), reset is only generated at second wdt overflow
*/
if (!no_timeout)
timeout = 2 * ((1<<xdev.wdt_interval) / *pfreq);
if (!request_mem_region(xdev.res.start,
xdev.res.end - xdev.res.start + 1, WATCHDOG_NAME)) {
rc = -ENXIO;
printk(KERN_ERR PFX "memory request failure!\n");
goto err_out;
}
xdev.base = ioremap(xdev.res.start, xdev.res.end - xdev.res.start + 1);
if (xdev.base == NULL) {
rc = -ENOMEM;
printk(KERN_ERR PFX "ioremap failure!\n");
goto release_mem;
}
rc = xwdt_selftest();
if (rc == XWT_TIMER_FAILED) {
printk(KERN_ERR PFX "SelfTest routine error!\n");
goto unmap_io;
}
xwdt_get_status(&xdev.boot_status);
rc = misc_register(&xwdt_miscdev);
if (rc) {
printk(KERN_ERR PFX
"cannot register miscdev on minor=%d (err=%d)\n",
xwdt_miscdev.minor, rc);
goto unmap_io;
}
if (no_timeout)
printk(KERN_INFO PFX
"driver loaded (timeout=? sec, nowayout=%d)\n",
xdev.nowayout);
else
printk(KERN_INFO PFX
"driver loaded (timeout=%d sec, nowayout=%d)\n",
timeout, xdev.nowayout);
expect_close = 0;
clear_bit(0, &driver_open);
return 0;
unmap_io:
iounmap(xdev.base);
release_mem:
release_mem_region(xdev.res.start, resource_size(&xdev.res));
err_out:
return rc;
}
static int __devexit xwdt_remove(struct platform_device *dev)
{
misc_deregister(&xwdt_miscdev);
iounmap(xdev.base);
release_mem_region(xdev.res.start, resource_size(&xdev.res));
return 0;
}
/* Match table for of_platform binding */
static struct of_device_id __devinitdata xwdt_of_match[] = {
{ .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
{},
};
MODULE_DEVICE_TABLE(of, xwdt_of_match);
static struct platform_driver xwdt_driver = {
.probe = xwdt_probe,
.remove = __devexit_p(xwdt_remove),
.driver = {
.owner = THIS_MODULE,
.name = WATCHDOG_NAME,
.of_match_table = xwdt_of_match,
},
};
module_platform_driver(xwdt_driver);
MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
MODULE_DESCRIPTION("Xilinx Watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
