linux/drivers/watchdog/of_xilinx_wdt.c
Jean Delvare 487722cf2d watchdog: Get rid of MODULE_ALIAS_MISCDEV statements
I just can't find any value in MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR)
and MODULE_ALIAS_MISCDEV(TEMP_MINOR) statements.

Either the device is enumerated and the driver already has a module
alias (e.g. PCI, USB etc.) that will get the right driver loaded
automatically.

Or the device is not enumerated and loading its driver will lead to
more or less intrusive hardware poking. Such hardware poking should be
limited to a bare minimum, so the user should really decide which
drivers should be tried and in what order. Trying them all in
arbitrary order can't do any good.

On top of that, loading that many drivers at once bloats the kernel
log. Also many drivers will stay loaded afterward, bloating the output
of "lsmod" and wasting memory. Some modules (cs5535_mfgpt which gets
loaded as a dependency) can't even be unloaded!

If defining char-major-10-130 is needed then it should happen in
user-space.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Mike Frysinger <vapier.adi@gmail.com>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk>
Cc: Jim Cromie <jim.cromie@gmail.com>
2013-11-17 19:38:13 +01:00

408 lines
9.2 KiB
C

/*
* Watchdog Device Driver for Xilinx axi/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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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);
pr_info("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();
pr_info("Started...\n");
return nonseekable_open(inode, file);
}
static int xwdt_release(struct inode *inode, struct file *file)
{
if (expect_close == 42) {
xwdt_stop();
} else {
pr_crit("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 xwdt_probe(struct platform_device *pdev)
{
int rc;
u32 *tmptr;
u32 *pfreq;
no_timeout = 0;
pfreq = (u32 *)of_get_property(pdev->dev.of_node,
"clock-frequency", NULL);
if (pfreq == NULL) {
pr_warn("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) {
pr_warn("invalid address!\n");
return rc;
}
tmptr = (u32 *)of_get_property(pdev->dev.of_node,
"xlnx,wdt-interval", NULL);
if (tmptr == NULL) {
pr_warn("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) {
pr_warn("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;
pr_err("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;
pr_err("ioremap failure!\n");
goto release_mem;
}
rc = xwdt_selftest();
if (rc == XWT_TIMER_FAILED) {
pr_err("SelfTest routine error!\n");
goto unmap_io;
}
xwdt_get_status(&xdev.boot_status);
rc = misc_register(&xwdt_miscdev);
if (rc) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
xwdt_miscdev.minor, rc);
goto unmap_io;
}
if (no_timeout)
pr_info("driver loaded (timeout=? sec, nowayout=%d)\n",
xdev.nowayout);
else
pr_info("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 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 xwdt_of_match[] = {
{ .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
{ .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 = 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 v2");