diff options
Diffstat (limited to 'drivers/watchdog/aspeed_wdt.c')
| -rw-r--r-- | drivers/watchdog/aspeed_wdt.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c new file mode 100644 index 000000000000..a1ea4c286e6c --- /dev/null +++ b/drivers/watchdog/aspeed_wdt.c @@ -0,0 +1,224 @@ +/* + * Copyright 2015 IBM Corp. + * + * Joel Stanley <joel@jms.id.au> + * + * Based on the qcom-watchdog driver + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/reboot.h> +#include <linux/watchdog.h> +#include <linux/platform_device.h> +#include <linux/clk.h> +#include <linux/io.h> + +struct aspeed_wdt { + struct watchdog_device wdd; + struct clk *clk; + unsigned long rate; + struct notifier_block restart_nb; + void __iomem *base; +}; + +static const struct of_device_id aspeed_wdt_of_table[] = { + { .compatible = "aspeed,wdt", }, + { }, +}; +MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table); + +#define WDT_STATUS 0x00 +#define WDT_RELOAD_VALUE 0x04 +#define WDT_RESTART 0x08 +#define WDT_CTRL 0x0C +#define WDT_CTRL_RESET_MODE_SOC (0x00 << 5) +#define WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5) +#define WDT_CTRL_RESET_SYSTEM (0x1 << 1) +#define WDT_CTRL_ENABLE (0x1 << 0) + +#define WDT_RESTART_MAGIC 0x4755 + +static void aspeed_wdt_enable(struct aspeed_wdt *wdt, int count) +{ + u32 ctrl = WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM | + WDT_CTRL_ENABLE; + + writel(0, wdt->base + WDT_CTRL); + writel(count, wdt->base + WDT_RELOAD_VALUE); + writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART); + writel(ctrl, wdt->base + WDT_CTRL); +} + +static int aspeed_wdt_start(struct watchdog_device *wdd) +{ + struct aspeed_wdt *wdt = container_of(wdd, struct aspeed_wdt, wdd); + dev_dbg(wdd->dev, "starting with timeout of %d (rate %lu)\n", + wdd->timeout, wdt->rate); + aspeed_wdt_enable(wdt, wdd->timeout * wdt->rate); + return 0; +} + +static int aspeed_wdt_stop(struct watchdog_device *wdd) +{ + struct aspeed_wdt *wdt = container_of(wdd, struct aspeed_wdt, wdd); + + writel(0, wdt->base + WDT_CTRL); + return 0; +} + +static int aspeed_wdt_ping(struct watchdog_device *wdd) +{ + struct aspeed_wdt *wdt = container_of(wdd, struct aspeed_wdt, wdd); + + dev_dbg(wdd->dev, "ping\n"); + writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART); + return 0; +} + +static int aspeed_wdt_set_timeout(struct watchdog_device *wdd, + unsigned int timeout) +{ + dev_dbg(wdd->dev, "timeout set to %u\n", timeout); + wdd->timeout = timeout; + return aspeed_wdt_start(wdd); +} + +static int aspeed_wdt_restart(struct notifier_block *nb, unsigned long action, + void *data) +{ + struct aspeed_wdt *wdt = container_of(nb, + struct aspeed_wdt, restart_nb); + + /* + * Trigger watchdog bite: + * Setup reload count to be 128ms, and enable WDT. + */ + aspeed_wdt_enable(wdt, 128 * wdt->rate / 1000); + + return NOTIFY_DONE; +} + +static const struct watchdog_ops aspeed_wdt_ops = { + .start = aspeed_wdt_start, + .stop = aspeed_wdt_stop, + .ping = aspeed_wdt_ping, + .set_timeout = aspeed_wdt_set_timeout, + .owner = THIS_MODULE, +}; + +static const struct watchdog_info aspeed_wdt_info = { + .options = WDIOF_KEEPALIVEPING + | WDIOF_MAGICCLOSE + | WDIOF_SETTIMEOUT, + .identity = KBUILD_MODNAME, +}; + +static int aspeed_wdt_remove(struct platform_device *pdev) +{ + struct aspeed_wdt *wdt = platform_get_drvdata(pdev); + + unregister_restart_handler(&wdt->restart_nb); + watchdog_unregister_device(&wdt->wdd); + clk_disable_unprepare(wdt->clk); + return 0; +} + +static int aspeed_wdt_probe(struct platform_device *pdev) +{ + struct aspeed_wdt *wdt; + struct resource *res; + int ret; + + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); + if (!wdt) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + wdt->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(wdt->base)) + return PTR_ERR(wdt->base); + + wdt->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(wdt->clk)) { + dev_err(&pdev->dev, "failed to get input clock\n"); + return PTR_ERR(wdt->clk); + } + + ret = clk_prepare_enable(wdt->clk); + if (ret) { + dev_err(&pdev->dev, "failed to setup clock\n"); + goto err; + } + + /* + * We use the clock rate to calculate the max timeout, so ensure it's + * not zero to avoid a divide-by-zero exception. + * + * WATCHDOG_CORE assumes units of seconds, if the WDT is clocked such + * that it would bite before a second elapses it's usefulness is + * limited. Bail if this is the case. + */ + wdt->rate = clk_get_rate(wdt->clk); + if (wdt->rate == 0 || + wdt->rate > 0x10000000U) { + dev_err(&pdev->dev, "invalid clock rate\n"); + ret = -EINVAL; + goto err; + } + + wdt->wdd.dev = &pdev->dev; + wdt->wdd.info = &aspeed_wdt_info; + wdt->wdd.ops = &aspeed_wdt_ops; + wdt->wdd.min_timeout = 1; + wdt->wdd.max_timeout = 0x10000000U / wdt->rate; + + /* + * If 'timeout-sec' unspecified in devicetree, assume a 30 second + * default, unless the max timeout is less than 30 seconds, then use + * the max instead. + */ + wdt->wdd.timeout = min(wdt->wdd.max_timeout, 30U); + watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev); + + ret = watchdog_register_device(&wdt->wdd); + if (ret) { + dev_err(&pdev->dev, "failed to register\n"); + goto err; + } + + /* + * WDT restart notifier has priority 0 (use as a last resort) + */ + wdt->restart_nb.notifier_call = aspeed_wdt_restart; + ret = register_restart_handler(&wdt->restart_nb); + if (ret) + dev_err(&pdev->dev, "failed to setup restart handler\n"); + + dev_info(&pdev->dev, "rate %lu, max timeout %u, timeout %d\n", + wdt->rate, wdt->wdd.max_timeout, wdt->wdd.timeout); + + platform_set_drvdata(pdev, wdt); + return 0; + +err: + clk_disable_unprepare(wdt->clk); + return ret; +} + +static struct platform_driver aspeed_watchdog_driver = { + .probe = aspeed_wdt_probe, + .remove = aspeed_wdt_remove, + .driver = { + .name = KBUILD_MODNAME, + .of_match_table = of_match_ptr(aspeed_wdt_of_table), + }, +}; +module_platform_driver(aspeed_watchdog_driver); + +MODULE_DESCRIPTION("Aspeed AST23/4xx Watchdog Driver"); |