--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020 TOSHIBA CORPORATION
+ * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
+ * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
+ */
+
+#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/watchdog.h>
+
+#define WDT_CNT 0x00
+#define WDT_MIN 0x04
+#define WDT_MAX 0x08
+#define WDT_CTL 0x0c
+#define WDT_CMD 0x10
+#define WDT_CMD_CLEAR 0x4352
+#define WDT_CMD_START_STOP 0x5354
+#define WDT_DIV 0x30
+
+#define VISCONTI_WDT_FREQ 2000000 /* 2MHz */
+#define WDT_DEFAULT_TIMEOUT 10U /* in seconds */
+
+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 visconti_wdt_priv {
+ struct watchdog_device wdev;
+ void __iomem *base;
+ u32 div;
+};
+
+static int visconti_wdt_start(struct watchdog_device *wdev)
+{
+ struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
+
+ writel(priv->div, priv->base + WDT_DIV);
+ writel(0, priv->base + WDT_MIN);
+ writel(timeout, priv->base + WDT_MAX);
+ writel(0, priv->base + WDT_CTL);
+ writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
+
+ return 0;
+}
+
+static int visconti_wdt_stop(struct watchdog_device *wdev)
+{
+ struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ writel(1, priv->base + WDT_CTL);
+ writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
+
+ return 0;
+}
+
+static int visconti_wdt_ping(struct watchdog_device *wdd)
+{
+ struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
+
+ return 0;
+}
+
+static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
+{
+ struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+ u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
+ u32 cnt = readl(priv->base + WDT_CNT);
+
+ if (timeout <= cnt)
+ return 0;
+ timeout -= cnt;
+
+ return timeout / VISCONTI_WDT_FREQ;
+}
+
+static int visconti_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
+{
+ u32 val;
+ struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
+
+ wdev->timeout = timeout;
+ val = wdev->timeout * VISCONTI_WDT_FREQ;
+
+ /* Clear counter before setting timeout because WDT expires */
+ writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
+ writel(val, priv->base + WDT_MAX);
+
+ return 0;
+}
+
+static const struct watchdog_info visconti_wdt_info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+ .identity = "Visconti Watchdog",
+};
+
+static const struct watchdog_ops visconti_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = visconti_wdt_start,
+ .stop = visconti_wdt_stop,
+ .ping = visconti_wdt_ping,
+ .get_timeleft = visconti_wdt_get_timeleft,
+ .set_timeout = visconti_wdt_set_timeout,
+};
+
+static void visconti_clk_disable_unprepare(void *data)
+{
+ clk_disable_unprepare(data);
+}
+
+static int visconti_wdt_probe(struct platform_device *pdev)
+{
+ struct watchdog_device *wdev;
+ struct visconti_wdt_priv *priv;
+ struct device *dev = &pdev->dev;
+ struct clk *clk;
+ int ret;
+ unsigned long clk_freq;
+
+ 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);
+
+ clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(clk))
+ return dev_err_probe(dev, PTR_ERR(clk), "Could not get clock\n");
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ dev_err(dev, "Could not enable clock\n");
+ return ret;
+ }
+
+ ret = devm_add_action_or_reset(dev, visconti_clk_disable_unprepare, clk);
+ if (ret)
+ return ret;
+
+ clk_freq = clk_get_rate(clk);
+ if (!clk_freq)
+ return -EINVAL;
+
+ priv->div = clk_freq / VISCONTI_WDT_FREQ;
+
+ /* Initialize struct watchdog_device. */
+ wdev = &priv->wdev;
+ wdev->info = &visconti_wdt_info;
+ wdev->ops = &visconti_wdt_ops;
+ wdev->parent = dev;
+ wdev->min_timeout = 1;
+ wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
+ wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
+
+ watchdog_set_drvdata(wdev, priv);
+ watchdog_set_nowayout(wdev, nowayout);
+ watchdog_stop_on_unregister(wdev);
+
+ /* This overrides the default timeout only if DT configuration was found */
+ ret = watchdog_init_timeout(wdev, 0, dev);
+ if (ret)
+ dev_warn(dev, "Specified timeout value invalid, using default\n");
+
+ return devm_watchdog_register_device(dev, wdev);
+}
+
+static const struct of_device_id visconti_wdt_of_match[] = {
+ { .compatible = "toshiba,visconti-wdt", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
+
+static struct platform_driver visconti_wdt_driver = {
+ .driver = {
+ .name = "visconti_wdt",
+ .of_match_table = visconti_wdt_of_match,
+ },
+ .probe = visconti_wdt_probe,
+};
+module_platform_driver(visconti_wdt_driver);
+
+MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
+MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp");
+MODULE_LICENSE("GPL v2");
projects / platform / kernel / linux-rpi.git / commitdiff