1 files changed, 344 insertions, 0 deletions
diff --git a/drivers/watchdog/shwdt.c b/drivers/watchdog/shwdt.c
new file mode 100644
index 000000000..f55533e0e
--- /dev/null
+++ b/drivers/watchdog/shwdt.c
@@ -0,0 +1,344 @@
+// 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) ")");