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Diffstat (limited to 'drivers/watchdog/renesas_wdt.c')
-rw-r--r--drivers/watchdog/renesas_wdt.c346
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>");