diff options
Diffstat (limited to 'drivers/watchdog/visconti_wdt.c')
| -rw-r--r-- | drivers/watchdog/visconti_wdt.c | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/drivers/watchdog/visconti_wdt.c b/drivers/watchdog/visconti_wdt.c new file mode 100644 index 000000000..83ef55e66 --- /dev/null +++ b/drivers/watchdog/visconti_wdt.c @@ -0,0 +1,195 @@ +// 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"); |