diff options
Diffstat (limited to 'drivers/watchdog/renesas_wdt.c')
| -rw-r--r-- | drivers/watchdog/renesas_wdt.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c new file mode 100644 index 000000000000..cf61c92f7ecd --- /dev/null +++ b/drivers/watchdog/renesas_wdt.c @@ -0,0 +1,213 @@ +/* + * 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>"); |