--- /dev/null
+/*
+ * Watchdog driver for Renesas WDT watchdog
+ *
+ * Copyright (C) 2015-16 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
+ * Copyright (C) 2015-16 Renesas Electronics Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/io.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/watchdog.h>
+
+#define RWTCNT 0
+#define RWTCSRA 4
+#define RWTCSRA_WOVF BIT(4)
+#define RWTCSRA_WRFLG BIT(5)
+#define RWTCSRA_TME BIT(7)
+
+#define RWDT_DEFAULT_TIMEOUT 60U
+
+static const unsigned int clk_divs[] = { 1, 4, 16, 32, 64, 128, 1024 };
+
+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;
+ struct clk *clk;
+ unsigned int clks_per_sec;
+ u8 cks;
+};
+
+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 - wdev->timeout * priv->clks_per_sec, RWTCNT);
+
+ return 0;
+}
+
+static int rwdt_start(struct watchdog_device *wdev)
+{
+ struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ clk_prepare_enable(priv->clk);
+
+ rwdt_write(priv, priv->cks, RWTCSRA);
+ rwdt_init_timeout(wdev);
+
+ 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);
+ clk_disable_unprepare(priv->clk);
+
+ 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_ROUND_CLOSEST(65536 - val, priv->clks_per_sec);
+}
+
+static const struct watchdog_info rwdt_ident = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+ .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,
+};
+
+static int rwdt_probe(struct platform_device *pdev)
+{
+ struct rwdt_priv *priv;
+ struct resource *res;
+ unsigned long rate;
+ unsigned int clks_per_sec;
+ int ret, i;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ priv->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(priv->base))
+ return PTR_ERR(priv->base);
+
+ priv->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(priv->clk))
+ return PTR_ERR(priv->clk);
+
+ rate = clk_get_rate(priv->clk);
+ if (!rate)
+ return -ENOENT;
+
+ for (i = ARRAY_SIZE(clk_divs) - 1; i >= 0; i--) {
+ clks_per_sec = DIV_ROUND_UP(rate, clk_divs[i]);
+ if (clks_per_sec) {
+ priv->clks_per_sec = clks_per_sec;
+ priv->cks = i;
+ break;
+ }
+ }
+
+ if (!clks_per_sec) {
+ dev_err(&pdev->dev, "Can't find suitable clock divider\n");
+ return -ERANGE;
+ }
+
+ pm_runtime_enable(&pdev->dev);
+ pm_runtime_get_sync(&pdev->dev);
+
+ priv->wdev.info = &rwdt_ident,
+ priv->wdev.ops = &rwdt_ops,
+ priv->wdev.parent = &pdev->dev;
+ priv->wdev.min_timeout = 1;
+ priv->wdev.max_timeout = 65536 / clks_per_sec;
+ 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);
+
+ /* This overrides the default timeout only if DT configuration was found */
+ ret = watchdog_init_timeout(&priv->wdev, 0, &pdev->dev);
+ if (ret)
+ dev_warn(&pdev->dev, "Specified timeout value invalid, using default\n");
+
+ ret = watchdog_register_device(&priv->wdev);
+ if (ret < 0) {
+ pm_runtime_put(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int rwdt_remove(struct platform_device *pdev)
+{
+ struct rwdt_priv *priv = platform_get_drvdata(pdev);
+
+ watchdog_unregister_device(&priv->wdev);
+ pm_runtime_put(&pdev->dev);
+ pm_runtime_disable(&pdev->dev);
+
+ return 0;
+}
+
+/*
+ * This driver does also fit for R-Car Gen2 (r8a779[0-4]) WDT. However, for SMP
+ * to work there, one also needs a RESET (RST) driver which does not exist yet
+ * due to HW issues. This needs to be solved before adding compatibles here.
+ */
+static const struct of_device_id rwdt_ids[] = {
+ { .compatible = "renesas,rcar-gen3-wdt", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rwdt_ids);
+
+static struct platform_driver rwdt_driver = {
+ .driver = {
+ .name = "renesas_wdt",
+ .of_match_table = rwdt_ids,
+ },
+ .probe = rwdt_probe,
+ .remove = 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>");
projects / cascardo / linux.git / commitdiff