1 files changed, 386 insertions, 0 deletions
diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
new file mode 100644
index 000000000..aeee934ca
--- /dev/null
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -0,0 +1,386 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Atmel SAMA5D4 Watchdog Timer
+ *
+ * Copyright (C) 2015-2019 Microchip Technology Inc. and its subsidiaries
+ */
+
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+
+#include "at91sam9_wdt.h"
+
+/* minimum and maximum watchdog timeout, in seconds */
+#define MIN_WDT_TIMEOUT		1
+#define MAX_WDT_TIMEOUT		16
+#define WDT_DEFAULT_TIMEOUT	MAX_WDT_TIMEOUT
+
+#define WDT_SEC2TICKS(s)	((s) ? (((s) << 8) - 1) : 0)
+
+struct sama5d4_wdt {
+	struct watchdog_device	wdd;
+	void __iomem		*reg_base;
+	u32			mr;
+	u32			ir;
+	unsigned long		last_ping;
+	bool			need_irq;
+	bool			sam9x60_support;
+};
+
+static int wdt_timeout;
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+module_param(wdt_timeout, int, 0);
+MODULE_PARM_DESC(wdt_timeout,
+	"Watchdog timeout in seconds. (default = "
+	__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
+
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout,
+	"Watchdog cannot be stopped once started (default="
+	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
+
+#define wdt_read(wdt, field) \
+	readl_relaxed((wdt)->reg_base + (field))
+
+/* 4 slow clock periods is 4/32768 = 122.07µs*/
+#define WDT_DELAY	usecs_to_jiffies(123)
+
+static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
+{
+	/*
+	 * WDT_CR and WDT_MR must not be modified within three slow clock
+	 * periods following a restart of the watchdog performed by a write
+	 * access in WDT_CR.
+	 */
+	while (time_before(jiffies, wdt->last_ping + WDT_DELAY))
+		usleep_range(30, 125);
+	writel_relaxed(val, wdt->reg_base + field);
+	wdt->last_ping = jiffies;
+}
+
+static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
+{
+	if (time_before(jiffies, wdt->last_ping + WDT_DELAY))
+		udelay(123);
+	writel_relaxed(val, wdt->reg_base + field);
+	wdt->last_ping = jiffies;
+}
+
+static int sama5d4_wdt_start(struct watchdog_device *wdd)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	if (wdt->sam9x60_support) {
+		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
+		wdt->mr &= ~AT91_SAM9X60_WDDIS;
+	} else {
+		wdt->mr &= ~AT91_WDT_WDDIS;
+	}
+	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+
+	return 0;
+}
+
+static int sama5d4_wdt_stop(struct watchdog_device *wdd)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	if (wdt->sam9x60_support) {
+		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
+		wdt->mr |= AT91_SAM9X60_WDDIS;
+	} else {
+		wdt->mr |= AT91_WDT_WDDIS;
+	}
+	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
+
+	return 0;
+}
+
+static int sama5d4_wdt_ping(struct watchdog_device *wdd)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+
+	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
+
+	return 0;
+}
+
+static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
+				 unsigned int timeout)
+{
+	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
+	u32 value = WDT_SEC2TICKS(timeout);
+
+	if (wdt->sam9x60_support) {
+		wdt_write(wdt, AT91_SAM9X60_WLR,
+			  AT91_SAM9X60_SET_COUNTER(value));
+
+		wdd->timeout = timeout;
+		return 0;
+	}
+
+	wdt->mr &= ~AT91_WDT_WDV;
+	wdt->mr |= AT91_WDT_SET_WDV(value);
+
+	/*
+	 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
+	 * setting the WDDIS bit, and while it is set, the fields WDV and WDD
+	 * must not be modified.
+	 * If the watchdog is enabled, then the timeout can be updated. Else,
+	 * wait that the user enables it.
+	 */
+	if (wdt_enabled)
+		wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
+
+	wdd->timeout = timeout;
+
+	return 0;
+}
+
+static const struct watchdog_info sama5d4_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+	.identity = "Atmel SAMA5D4 Watchdog",
+};
+
+static const struct watchdog_ops sama5d4_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = sama5d4_wdt_start,
+	.stop = sama5d4_wdt_stop,
+	.ping = sama5d4_wdt_ping,
+	.set_timeout = sama5d4_wdt_set_timeout,
+};
+
+static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
+{
+	struct sama5d4_wdt *wdt = platform_get_drvdata(dev_id);
+	u32 reg;
+
+	if (wdt->sam9x60_support)
+		reg = wdt_read(wdt, AT91_SAM9X60_ISR);
+	else
+		reg = wdt_read(wdt, AT91_WDT_SR);
+
+	if (reg) {
+		pr_crit("Atmel Watchdog Software Reset\n");
+		emergency_restart();
+		pr_crit("Reboot didn't succeed\n");
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
+{
+	const char *tmp;
+
+	if (wdt->sam9x60_support)
+		wdt->mr = AT91_SAM9X60_WDDIS;
+	else
+		wdt->mr = AT91_WDT_WDDIS;
+
+	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
+	    !strcmp(tmp, "software"))
+		wdt->need_irq = true;
+
+	if (of_property_read_bool(np, "atmel,idle-halt"))
+		wdt->mr |= AT91_WDT_WDIDLEHLT;
+
+	if (of_property_read_bool(np, "atmel,dbg-halt"))
+		wdt->mr |= AT91_WDT_WDDBGHLT;
+
+	return 0;
+}
+
+static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
+{
+	u32 reg, val;
+
+	val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
+	/*
+	 * When booting and resuming, the bootloader may have changed the
+	 * watchdog configuration.
+	 * If the watchdog is already running, we can safely update it.
+	 * Else, we have to disable it properly.
+	 */
+	if (!wdt_enabled) {
+		reg = wdt_read(wdt, AT91_WDT_MR);
+		if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
+			wdt_write_nosleep(wdt, AT91_WDT_MR,
+					  reg | AT91_SAM9X60_WDDIS);
+		else if (!wdt->sam9x60_support &&
+			 (!(reg & AT91_WDT_WDDIS)))
+			wdt_write_nosleep(wdt, AT91_WDT_MR,
+					  reg | AT91_WDT_WDDIS);
+	}
+
+	if (wdt->sam9x60_support) {
+		if (wdt->need_irq)
+			wdt->ir = AT91_SAM9X60_PERINT;
+		else
+			wdt->mr |= AT91_SAM9X60_PERIODRST;
+
+		wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir);
+		wdt_write(wdt, AT91_SAM9X60_WLR, AT91_SAM9X60_SET_COUNTER(val));
+	} else {
+		wdt->mr |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(MAX_WDT_TIMEOUT));
+		wdt->mr |= AT91_WDT_SET_WDV(val);
+
+		if (wdt->need_irq)
+			wdt->mr |= AT91_WDT_WDFIEN;
+		else
+			wdt->mr |= AT91_WDT_WDRSTEN;
+	}
+
+	wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr);
+
+	return 0;
+}
+
+static int sama5d4_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	struct sama5d4_wdt *wdt;
+	void __iomem *regs;
+	u32 irq = 0;
+	int ret;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdd = &wdt->wdd;
+	wdd->timeout = WDT_DEFAULT_TIMEOUT;
+	wdd->info = &sama5d4_wdt_info;
+	wdd->ops = &sama5d4_wdt_ops;
+	wdd->min_timeout = MIN_WDT_TIMEOUT;
+	wdd->max_timeout = MAX_WDT_TIMEOUT;
+	wdt->last_ping = jiffies;
+
+	if (of_device_is_compatible(dev->of_node, "microchip,sam9x60-wdt") ||
+	    of_device_is_compatible(dev->of_node, "microchip,sama7g5-wdt"))
+		wdt->sam9x60_support = true;
+
+	watchdog_set_drvdata(wdd, wdt);
+
+	regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	wdt->reg_base = regs;
+
+	ret = of_sama5d4_wdt_init(dev->of_node, wdt);
+	if (ret)
+		return ret;
+
+	if (wdt->need_irq) {
+		irq = irq_of_parse_and_map(dev->of_node, 0);
+		if (!irq) {
+			dev_warn(dev, "failed to get IRQ from DT\n");
+			wdt->need_irq = false;
+		}
+	}
+
+	if (wdt->need_irq) {
+		ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
+				       IRQF_SHARED | IRQF_IRQPOLL |
+				       IRQF_NO_SUSPEND, pdev->name, pdev);
+		if (ret) {
+			dev_err(dev, "cannot register interrupt handler\n");
+			return ret;
+		}
+	}
+
+	watchdog_init_timeout(wdd, wdt_timeout, dev);
+
+	ret = sama5d4_wdt_init(wdt);
+	if (ret)
+		return ret;
+
+	watchdog_set_nowayout(wdd, nowayout);
+
+	watchdog_stop_on_unregister(wdd);
+	ret = devm_watchdog_register_device(dev, wdd);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, wdt);
+
+	dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
+		 wdd->timeout, nowayout);
+
+	return 0;
+}
+
+static const struct of_device_id sama5d4_wdt_of_match[] = {
+	{
+		.compatible = "atmel,sama5d4-wdt",
+	},
+	{
+		.compatible = "microchip,sam9x60-wdt",
+	},
+	{
+		.compatible = "microchip,sama7g5-wdt",
+	},
+
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sama5d4_wdt_of_match);
+
+static int sama5d4_wdt_suspend_late(struct device *dev)
+{
+	struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(&wdt->wdd))
+		sama5d4_wdt_stop(&wdt->wdd);
+
+	return 0;
+}
+
+static int sama5d4_wdt_resume_early(struct device *dev)
+{
+	struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
+
+	/*
+	 * FIXME: writing MR also pings the watchdog which may not be desired.
+	 * This should only be done when the registers are lost on suspend but
+	 * there is no way to get this information right now.
+	 */
+	sama5d4_wdt_init(wdt);
+
+	if (watchdog_active(&wdt->wdd))
+		sama5d4_wdt_start(&wdt->wdd);
+
+	return 0;
+}
+
+static const struct dev_pm_ops sama5d4_wdt_pm_ops = {
+	LATE_SYSTEM_SLEEP_PM_OPS(sama5d4_wdt_suspend_late,
+				 sama5d4_wdt_resume_early)
+};
+
+static struct platform_driver sama5d4_wdt_driver = {
+	.probe		= sama5d4_wdt_probe,
+	.driver		= {
+		.name	= "sama5d4_wdt",
+		.pm	= pm_sleep_ptr(&sama5d4_wdt_pm_ops),
+		.of_match_table = sama5d4_wdt_of_match,
+	}
+};
+module_platform_driver(sama5d4_wdt_driver);
+
+MODULE_AUTHOR("Atmel Corporation");
+MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
+MODULE_LICENSE("GPL v2");