1 files changed, 346 insertions, 0 deletions

diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
new file mode 100644
index 0000000000..12c41d6e5c
--- /dev/null
+++ b/drivers/watchdog/renesas_wdt.c
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Watchdog driver for Renesas WDT watchdog
+ *
+ * Copyright (C) 2015-17 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
+ * Copyright (C) 2015-17 Renesas Electronics Corporation
+ */
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/smp.h>
+#include <linux/sys_soc.h>
+#include <linux/watchdog.h>
+
+#define RWTCNT		0
+#define RWTCSRA		4
+#define RWTCSRA_WOVF	BIT(4)
+#define RWTCSRA_WRFLG	BIT(5)
+#define RWTCSRA_TME	BIT(7)
+#define RWTCSRB		8
+
+#define RWDT_DEFAULT_TIMEOUT 60U
+
+/*
+ * In probe, clk_rate is checked to be not more than 16 bit * biggest clock
+ * divider (12 bits). d is only a factor to fully utilize the WDT counter and
+ * will not exceed its 16 bits. Thus, no overflow, we stay below 32 bits.
+ */
+#define MUL_BY_CLKS_PER_SEC(p, d) \
+	DIV_ROUND_UP((d) * (p)->clk_rate, clk_divs[(p)->cks])
+
+/* d is 16 bit, clk_divs 12 bit -> no 32 bit overflow */
+#define DIV_BY_CLKS_PER_SEC(p, d) ((d) * clk_divs[(p)->cks] / (p)->clk_rate)
+
+static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024, 4096 };
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct rwdt_priv {
+	void __iomem *base;
+	struct watchdog_device wdev;
+	unsigned long clk_rate;
+	u8 cks;
+	struct clk *clk;
+};
+
+static void rwdt_write(struct rwdt_priv *priv, u32 val, unsigned int reg)
+{
+	if (reg == RWTCNT)
+		val |= 0x5a5a0000;
+	else
+		val |= 0xa5a5a500;
+
+	writel_relaxed(val, priv->base + reg);
+}
+
+static int rwdt_init_timeout(struct watchdog_device *wdev)
+{
+	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	rwdt_write(priv, 65536 - MUL_BY_CLKS_PER_SEC(priv, wdev->timeout), RWTCNT);
+
+	return 0;
+}
+
+static void rwdt_wait_cycles(struct rwdt_priv *priv, unsigned int cycles)
+{
+	unsigned int delay;
+
+	delay = DIV_ROUND_UP(cycles * 1000000, priv->clk_rate);
+
+	usleep_range(delay, 2 * delay);
+}
+
+static int rwdt_start(struct watchdog_device *wdev)
+{
+	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+	u8 val;
+
+	pm_runtime_get_sync(wdev->parent);
+
+	/* Stop the timer before we modify any register */
+	val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
+	rwdt_write(priv, val, RWTCSRA);
+	/* Delay 2 cycles before setting watchdog counter */
+	rwdt_wait_cycles(priv, 2);
+
+	rwdt_init_timeout(wdev);
+	rwdt_write(priv, priv->cks, RWTCSRA);
+	rwdt_write(priv, 0, RWTCSRB);
+
+	while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
+		cpu_relax();
+
+	rwdt_write(priv, priv->cks | RWTCSRA_TME, RWTCSRA);
+
+	return 0;
+}
+
+static int rwdt_stop(struct watchdog_device *wdev)
+{
+	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+
+	rwdt_write(priv, priv->cks, RWTCSRA);
+	/* Delay 3 cycles before disabling module clock */
+	rwdt_wait_cycles(priv, 3);
+	pm_runtime_put(wdev->parent);
+
+	return 0;
+}
+
+static unsigned int rwdt_get_timeleft(struct watchdog_device *wdev)
+{
+	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+	u16 val = readw_relaxed(priv->base + RWTCNT);
+
+	return DIV_BY_CLKS_PER_SEC(priv, 65536 - val);
+}
+
+/* needs to be atomic - no RPM, no usleep_range, no scheduling! */
+static int rwdt_restart(struct watchdog_device *wdev, unsigned long action,
+			void *data)
+{
+	struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+	u8 val;
+
+	clk_prepare_enable(priv->clk);
+
+	/* Stop the timer before we modify any register */
+	val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
+	rwdt_write(priv, val, RWTCSRA);
+	/* Delay 2 cycles before setting watchdog counter */
+	udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate));
+
+	rwdt_write(priv, 0xffff, RWTCNT);
+	/* smallest divider to reboot soon */
+	rwdt_write(priv, 0, RWTCSRA);
+
+	readb_poll_timeout_atomic(priv->base + RWTCSRA, val,
+				  !(val & RWTCSRA_WRFLG), 1, 100);
+
+	rwdt_write(priv, RWTCSRA_TME, RWTCSRA);
+
+	/* wait 2 cycles, so watchdog will trigger */
+	udelay(DIV_ROUND_UP(2 * 1000000, priv->clk_rate));
+
+	return 0;
+}
+
+static const struct watchdog_info rwdt_ident = {
+	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
+		WDIOF_CARDRESET,
+	.identity = "Renesas WDT Watchdog",
+};
+
+static const struct watchdog_ops rwdt_ops = {
+	.owner = THIS_MODULE,
+	.start = rwdt_start,
+	.stop = rwdt_stop,
+	.ping = rwdt_init_timeout,
+	.get_timeleft = rwdt_get_timeleft,
+	.restart = rwdt_restart,
+};
+
+#if defined(CONFIG_ARCH_RCAR_GEN2) && defined(CONFIG_SMP)
+/*
+ * Watchdog-reset integration is broken on early revisions of R-Car Gen2 SoCs
+ */
+static const struct soc_device_attribute rwdt_quirks_match[] = {
+	{
+		.soc_id = "r8a7790",
+		.revision = "ES1.*",
+		.data = (void *)1,	/* needs single CPU */
+	}, {
+		.soc_id = "r8a7791",
+		.revision = "ES1.*",
+		.data = (void *)1,	/* needs single CPU */
+	}, {
+		.soc_id = "r8a7792",
+		.data = (void *)0,	/* needs SMP disabled */
+	},
+	{ /* sentinel */ }
+};
+
+static bool rwdt_blacklisted(struct device *dev)
+{
+	const struct soc_device_attribute *attr;
+
+	attr = soc_device_match(rwdt_quirks_match);
+	if (attr && setup_max_cpus > (uintptr_t)attr->data) {
+		dev_info(dev, "Watchdog blacklisted on %s %s\n", attr->soc_id,
+			 attr->revision);
+		return true;
+	}
+
+	return false;
+}
+#else /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
+static inline bool rwdt_blacklisted(struct device *dev) { return false; }
+#endif /* !CONFIG_ARCH_RCAR_GEN2 || !CONFIG_SMP */
+
+static int rwdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rwdt_priv *priv;
+	unsigned long clks_per_sec;
+	int ret, i;
+	u8 csra;
+
+	if (rwdt_blacklisted(dev))
+		return -ENODEV;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	priv->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(priv->clk))
+		return PTR_ERR(priv->clk);
+
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+	priv->clk_rate = clk_get_rate(priv->clk);
+	csra = readb_relaxed(priv->base + RWTCSRA);
+	priv->wdev.bootstatus = csra & RWTCSRA_WOVF ? WDIOF_CARDRESET : 0;
+	pm_runtime_put(dev);
+
+	if (!priv->clk_rate) {
+		ret = -ENOENT;
+		goto out_pm_disable;
+	}
+
+	for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
+		clks_per_sec = priv->clk_rate / clk_divs[i];
+		if (clks_per_sec && clks_per_sec < 65536) {
+			priv->cks = i;
+			break;
+		}
+	}
+
+	if (i < 0) {
+		dev_err(dev, "Can't find suitable clock divider\n");
+		ret = -ERANGE;
+		goto out_pm_disable;
+	}
+
+	priv->wdev.info = &rwdt_ident;
+	priv->wdev.ops = &rwdt_ops;
+	priv->wdev.parent = dev;
+	priv->wdev.min_timeout = 1;
+	priv->wdev.max_timeout = DIV_BY_CLKS_PER_SEC(priv, 65536);
+	priv->wdev.timeout = min(priv->wdev.max_timeout, RWDT_DEFAULT_TIMEOUT);
+
+	platform_set_drvdata(pdev, priv);
+	watchdog_set_drvdata(&priv->wdev, priv);
+	watchdog_set_nowayout(&priv->wdev, nowayout);
+	watchdog_set_restart_priority(&priv->wdev, 0);
+	watchdog_stop_on_unregister(&priv->wdev);
+
+	/* This overrides the default timeout only if DT configuration was found */
+	watchdog_init_timeout(&priv->wdev, 0, dev);
+
+	/* Check if FW enabled the watchdog */
+	if (csra & RWTCSRA_TME) {
+		/* Ensure properly initialized dividers */
+		rwdt_start(&priv->wdev);
+		set_bit(WDOG_HW_RUNNING, &priv->wdev.status);
+	}
+
+	ret = watchdog_register_device(&priv->wdev);
+	if (ret < 0)
+		goto out_pm_disable;
+
+	return 0;
+
+ out_pm_disable:
+	pm_runtime_disable(dev);
+	return ret;
+}
+
+static void rwdt_remove(struct platform_device *pdev)
+{
+	struct rwdt_priv *priv = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&priv->wdev);
+	pm_runtime_disable(&pdev->dev);
+}
+
+static int __maybe_unused rwdt_suspend(struct device *dev)
+{
+	struct rwdt_priv *priv = dev_get_drvdata(dev);
+
+	if (watchdog_active(&priv->wdev))
+		rwdt_stop(&priv->wdev);
+
+	return 0;
+}
+
+static int __maybe_unused rwdt_resume(struct device *dev)
+{
+	struct rwdt_priv *priv = dev_get_drvdata(dev);
+
+	if (watchdog_active(&priv->wdev))
+		rwdt_start(&priv->wdev);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(rwdt_pm_ops, rwdt_suspend, rwdt_resume);
+
+static const struct of_device_id rwdt_ids[] = {
+	{ .compatible = "renesas,rcar-gen2-wdt", },
+	{ .compatible = "renesas,rcar-gen3-wdt", },
+	{ .compatible = "renesas,rcar-gen4-wdt", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rwdt_ids);
+
+static struct platform_driver rwdt_driver = {
+	.driver = {
+		.name = "renesas_wdt",
+		.of_match_table = rwdt_ids,
+		.pm = &rwdt_pm_ops,
+	},
+	.probe = rwdt_probe,
+	.remove_new = rwdt_remove,
+};
+module_platform_driver(rwdt_driver);
+
+MODULE_DESCRIPTION("Renesas WDT Watchdog Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");