linux/drivers/watchdog/shwdt.c
Thomas Gleixner 2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
Based on 1 normalized pattern(s):

  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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00

345 lines
8.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* drivers/watchdog/shwdt.c
*
* Watchdog driver for integrated watchdog in the SuperH processors.
*
* Copyright (C) 2001 - 2012 Paul Mundt <lethal@linux-sh.org>
*
* 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
* Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
*
* 19-Apr-2002 Rob Radez <rob@osinvestor.com>
* Added expect close support, made emulated timeout runtime changeable
* general cleanups, add some ioctls
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/watchdog.h>
#include <linux/pm_runtime.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <asm/watchdog.h>
#define DRV_NAME "sh-wdt"
/*
* Default clock division ratio is 5.25 msecs. For an additional table of
* values, consult the asm-sh/watchdog.h. Overload this at module load
* time.
*
* In order for this to work reliably we need to have HZ set to 1000 or
* something quite higher than 100 (or we need a proper high-res timer
* implementation that will deal with this properly), otherwise the 10ms
* resolution of a jiffy is enough to trigger the overflow. For things like
* the SH-4 and SH-5, this isn't necessarily that big of a problem, though
* for the SH-2 and SH-3, this isn't recommended unless the WDT is absolutely
* necssary.
*
* As a result of this timing problem, the only modes that are particularly
* feasible are the 4096 and the 2048 divisors, which yield 5.25 and 2.62ms
* overflow periods respectively.
*
* Also, since we can't really expect userspace to be responsive enough
* before the overflow happens, we maintain two separate timers .. One in
* the kernel for clearing out WOVF every 2ms or so (again, this depends on
* HZ == 1000), and another for monitoring userspace writes to the WDT device.
*
* As such, we currently use a configurable heartbeat interval which defaults
* to 30s. In this case, the userspace daemon is only responsible for periodic
* writes to the device before the next heartbeat is scheduled. If the daemon
* misses its deadline, the kernel timer will allow the WDT to overflow.
*/
static int clock_division_ratio = WTCSR_CKS_4096;
#define next_ping_period(cks) (jiffies + msecs_to_jiffies(cks - 4))
#define WATCHDOG_HEARTBEAT 30 /* 30 sec default heartbeat */
static int heartbeat = WATCHDOG_HEARTBEAT; /* in seconds */
static bool nowayout = WATCHDOG_NOWAYOUT;
static unsigned long next_heartbeat;
struct sh_wdt {
void __iomem *base;
struct device *dev;
struct clk *clk;
spinlock_t lock;
struct timer_list timer;
};
static int sh_wdt_start(struct watchdog_device *wdt_dev)
{
struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
unsigned long flags;
u8 csr;
pm_runtime_get_sync(wdt->dev);
clk_enable(wdt->clk);
spin_lock_irqsave(&wdt->lock, flags);
next_heartbeat = jiffies + (heartbeat * HZ);
mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
csr = sh_wdt_read_csr();
csr |= WTCSR_WT | clock_division_ratio;
sh_wdt_write_csr(csr);
sh_wdt_write_cnt(0);
/*
* These processors have a bit of an inconsistent initialization
* process.. starting with SH-3, RSTS was moved to WTCSR, and the
* RSTCSR register was removed.
*
* On the SH-2 however, in addition with bits being in different
* locations, we must deal with RSTCSR outright..
*/
csr = sh_wdt_read_csr();
csr |= WTCSR_TME;
csr &= ~WTCSR_RSTS;
sh_wdt_write_csr(csr);
#ifdef CONFIG_CPU_SH2
csr = sh_wdt_read_rstcsr();
csr &= ~RSTCSR_RSTS;
sh_wdt_write_rstcsr(csr);
#endif
spin_unlock_irqrestore(&wdt->lock, flags);
return 0;
}
static int sh_wdt_stop(struct watchdog_device *wdt_dev)
{
struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
unsigned long flags;
u8 csr;
spin_lock_irqsave(&wdt->lock, flags);
del_timer(&wdt->timer);
csr = sh_wdt_read_csr();
csr &= ~WTCSR_TME;
sh_wdt_write_csr(csr);
spin_unlock_irqrestore(&wdt->lock, flags);
clk_disable(wdt->clk);
pm_runtime_put_sync(wdt->dev);
return 0;
}
static int sh_wdt_keepalive(struct watchdog_device *wdt_dev)
{
struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
unsigned long flags;
spin_lock_irqsave(&wdt->lock, flags);
next_heartbeat = jiffies + (heartbeat * HZ);
spin_unlock_irqrestore(&wdt->lock, flags);
return 0;
}
static int sh_wdt_set_heartbeat(struct watchdog_device *wdt_dev, unsigned t)
{
struct sh_wdt *wdt = watchdog_get_drvdata(wdt_dev);
unsigned long flags;
if (unlikely(t < 1 || t > 3600)) /* arbitrary upper limit */
return -EINVAL;
spin_lock_irqsave(&wdt->lock, flags);
heartbeat = t;
wdt_dev->timeout = t;
spin_unlock_irqrestore(&wdt->lock, flags);
return 0;
}
static void sh_wdt_ping(struct timer_list *t)
{
struct sh_wdt *wdt = from_timer(wdt, t, timer);
unsigned long flags;
spin_lock_irqsave(&wdt->lock, flags);
if (time_before(jiffies, next_heartbeat)) {
u8 csr;
csr = sh_wdt_read_csr();
csr &= ~WTCSR_IOVF;
sh_wdt_write_csr(csr);
sh_wdt_write_cnt(0);
mod_timer(&wdt->timer, next_ping_period(clock_division_ratio));
} else
dev_warn(wdt->dev, "Heartbeat lost! Will not ping "
"the watchdog\n");
spin_unlock_irqrestore(&wdt->lock, flags);
}
static const struct watchdog_info sh_wdt_info = {
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE,
.firmware_version = 1,
.identity = "SH WDT",
};
static const struct watchdog_ops sh_wdt_ops = {
.owner = THIS_MODULE,
.start = sh_wdt_start,
.stop = sh_wdt_stop,
.ping = sh_wdt_keepalive,
.set_timeout = sh_wdt_set_heartbeat,
};
static struct watchdog_device sh_wdt_dev = {
.info = &sh_wdt_info,
.ops = &sh_wdt_ops,
};
static int sh_wdt_probe(struct platform_device *pdev)
{
struct sh_wdt *wdt;
int rc;
/*
* As this driver only covers the global watchdog case, reject
* any attempts to register per-CPU watchdogs.
*/
if (pdev->id != -1)
return -EINVAL;
wdt = devm_kzalloc(&pdev->dev, sizeof(struct sh_wdt), GFP_KERNEL);
if (unlikely(!wdt))
return -ENOMEM;
wdt->dev = &pdev->dev;
wdt->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(wdt->clk)) {
/*
* Clock framework support is optional, continue on
* anyways if we don't find a matching clock.
*/
wdt->clk = NULL;
}
wdt->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(wdt->base))
return PTR_ERR(wdt->base);
watchdog_set_nowayout(&sh_wdt_dev, nowayout);
watchdog_set_drvdata(&sh_wdt_dev, wdt);
sh_wdt_dev.parent = &pdev->dev;
spin_lock_init(&wdt->lock);
rc = sh_wdt_set_heartbeat(&sh_wdt_dev, heartbeat);
if (unlikely(rc)) {
/* Default timeout if invalid */
sh_wdt_set_heartbeat(&sh_wdt_dev, WATCHDOG_HEARTBEAT);
dev_warn(&pdev->dev,
"heartbeat value must be 1<=x<=3600, using %d\n",
sh_wdt_dev.timeout);
}
dev_info(&pdev->dev, "configured with heartbeat=%d sec (nowayout=%d)\n",
sh_wdt_dev.timeout, nowayout);
rc = watchdog_register_device(&sh_wdt_dev);
if (unlikely(rc)) {
dev_err(&pdev->dev, "Can't register watchdog (err=%d)\n", rc);
return rc;
}
timer_setup(&wdt->timer, sh_wdt_ping, 0);
wdt->timer.expires = next_ping_period(clock_division_ratio);
dev_info(&pdev->dev, "initialized.\n");
pm_runtime_enable(&pdev->dev);
return 0;
}
static int sh_wdt_remove(struct platform_device *pdev)
{
watchdog_unregister_device(&sh_wdt_dev);
pm_runtime_disable(&pdev->dev);
return 0;
}
static void sh_wdt_shutdown(struct platform_device *pdev)
{
sh_wdt_stop(&sh_wdt_dev);
}
static struct platform_driver sh_wdt_driver = {
.driver = {
.name = DRV_NAME,
},
.probe = sh_wdt_probe,
.remove = sh_wdt_remove,
.shutdown = sh_wdt_shutdown,
};
static int __init sh_wdt_init(void)
{
if (unlikely(clock_division_ratio < 0x5 ||
clock_division_ratio > 0x7)) {
clock_division_ratio = WTCSR_CKS_4096;
pr_info("divisor must be 0x5<=x<=0x7, using %d\n",
clock_division_ratio);
}
return platform_driver_register(&sh_wdt_driver);
}
static void __exit sh_wdt_exit(void)
{
platform_driver_unregister(&sh_wdt_driver);
}
module_init(sh_wdt_init);
module_exit(sh_wdt_exit);
MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("SuperH watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);
module_param(clock_division_ratio, int, 0);
MODULE_PARM_DESC(clock_division_ratio,
"Clock division ratio. Valid ranges are from 0x5 (1.31ms) "
"to 0x7 (5.25ms). (default=" __MODULE_STRING(WTCSR_CKS_4096) ")");
module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
"Watchdog heartbeat in seconds. (1 <= heartbeat <= 3600, default="
__MODULE_STRING(WATCHDOG_HEARTBEAT) ")");
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");