diff options
Diffstat (limited to 'drivers/watchdog/apple_wdt.c')
| -rw-r--r-- | drivers/watchdog/apple_wdt.c | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/drivers/watchdog/apple_wdt.c b/drivers/watchdog/apple_wdt.c new file mode 100644 index 000000000..16aca21f1 --- /dev/null +++ b/drivers/watchdog/apple_wdt.c @@ -0,0 +1,226 @@ +// SPDX-License-Identifier: GPL-2.0-only OR MIT +/* + * Apple SoC Watchdog driver + * + * Copyright (C) The Asahi Linux Contributors + */ + +#include <linux/bits.h> +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/limits.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/watchdog.h> + +/* + * Apple Watchdog MMIO registers + * + * This HW block has three separate watchdogs. WD0 resets the machine + * to recovery mode and is not very useful for us. WD1 and WD2 trigger a normal + * machine reset. WD0 additionally supports a configurable interrupt. + * This information can be used to implement pretimeout support at a later time. + * + * APPLE_WDT_WDx_CUR_TIME is a simple counter incremented for each tick of the + * reference clock. It can also be overwritten to any value. + * Whenever APPLE_WDT_CTRL_RESET_EN is set in APPLE_WDT_WDx_CTRL and + * APPLE_WDT_WDx_CUR_TIME >= APPLE_WDT_WDx_BITE_TIME the entire machine is + * reset. + * Whenever APPLE_WDT_CTRL_IRQ_EN is set and APPLE_WDTx_WD1_CUR_TIME >= + * APPLE_WDTx_WD1_BARK_TIME an interrupt is triggered and + * APPLE_WDT_CTRL_IRQ_STATUS is set. The interrupt can be cleared by writing + * 1 to APPLE_WDT_CTRL_IRQ_STATUS. + */ +#define APPLE_WDT_WD0_CUR_TIME 0x00 +#define APPLE_WDT_WD0_BITE_TIME 0x04 +#define APPLE_WDT_WD0_BARK_TIME 0x08 +#define APPLE_WDT_WD0_CTRL 0x0c + +#define APPLE_WDT_WD1_CUR_TIME 0x10 +#define APPLE_WDT_WD1_BITE_TIME 0x14 +#define APPLE_WDT_WD1_CTRL 0x1c + +#define APPLE_WDT_WD2_CUR_TIME 0x20 +#define APPLE_WDT_WD2_BITE_TIME 0x24 +#define APPLE_WDT_WD2_CTRL 0x2c + +#define APPLE_WDT_CTRL_IRQ_EN BIT(0) +#define APPLE_WDT_CTRL_IRQ_STATUS BIT(1) +#define APPLE_WDT_CTRL_RESET_EN BIT(2) + +#define APPLE_WDT_TIMEOUT_DEFAULT 30 + +struct apple_wdt { + struct watchdog_device wdd; + void __iomem *regs; + unsigned long clk_rate; +}; + +static struct apple_wdt *to_apple_wdt(struct watchdog_device *wdd) +{ + return container_of(wdd, struct apple_wdt, wdd); +} + +static int apple_wdt_start(struct watchdog_device *wdd) +{ + struct apple_wdt *wdt = to_apple_wdt(wdd); + + writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME); + writel_relaxed(APPLE_WDT_CTRL_RESET_EN, wdt->regs + APPLE_WDT_WD1_CTRL); + + return 0; +} + +static int apple_wdt_stop(struct watchdog_device *wdd) +{ + struct apple_wdt *wdt = to_apple_wdt(wdd); + + writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CTRL); + + return 0; +} + +static int apple_wdt_ping(struct watchdog_device *wdd) +{ + struct apple_wdt *wdt = to_apple_wdt(wdd); + + writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME); + + return 0; +} + +static int apple_wdt_set_timeout(struct watchdog_device *wdd, unsigned int s) +{ + struct apple_wdt *wdt = to_apple_wdt(wdd); + + writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME); + writel_relaxed(wdt->clk_rate * s, wdt->regs + APPLE_WDT_WD1_BITE_TIME); + + wdd->timeout = s; + + return 0; +} + +static unsigned int apple_wdt_get_timeleft(struct watchdog_device *wdd) +{ + struct apple_wdt *wdt = to_apple_wdt(wdd); + u32 cur_time, reset_time; + + cur_time = readl_relaxed(wdt->regs + APPLE_WDT_WD1_CUR_TIME); + reset_time = readl_relaxed(wdt->regs + APPLE_WDT_WD1_BITE_TIME); + + return (reset_time - cur_time) / wdt->clk_rate; +} + +static int apple_wdt_restart(struct watchdog_device *wdd, unsigned long mode, + void *cmd) +{ + struct apple_wdt *wdt = to_apple_wdt(wdd); + + writel_relaxed(APPLE_WDT_CTRL_RESET_EN, wdt->regs + APPLE_WDT_WD1_CTRL); + writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_BITE_TIME); + writel_relaxed(0, wdt->regs + APPLE_WDT_WD1_CUR_TIME); + + /* + * Flush writes and then wait for the SoC to reset. Even though the + * reset is queued almost immediately experiments have shown that it + * can take up to ~20-25ms until the SoC is actually reset. Just wait + * 50ms here to be safe. + */ + (void)readl_relaxed(wdt->regs + APPLE_WDT_WD1_CUR_TIME); + mdelay(50); + + return 0; +} + +static void apple_wdt_clk_disable_unprepare(void *data) +{ + clk_disable_unprepare(data); +} + +static struct watchdog_ops apple_wdt_ops = { + .owner = THIS_MODULE, + .start = apple_wdt_start, + .stop = apple_wdt_stop, + .ping = apple_wdt_ping, + .set_timeout = apple_wdt_set_timeout, + .get_timeleft = apple_wdt_get_timeleft, + .restart = apple_wdt_restart, +}; + +static struct watchdog_info apple_wdt_info = { + .identity = "Apple SoC Watchdog", + .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT, +}; + +static int apple_wdt_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct apple_wdt *wdt; + struct clk *clk; + u32 wdt_ctrl; + int ret; + + wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); + if (!wdt) + return -ENOMEM; + + wdt->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(wdt->regs)) + return PTR_ERR(wdt->regs); + + clk = devm_clk_get(dev, NULL); + if (IS_ERR(clk)) + return PTR_ERR(clk); + + ret = clk_prepare_enable(clk); + if (ret) + return ret; + + ret = devm_add_action_or_reset(dev, apple_wdt_clk_disable_unprepare, + clk); + if (ret) + return ret; + + wdt->clk_rate = clk_get_rate(clk); + if (!wdt->clk_rate) + return -EINVAL; + + wdt->wdd.ops = &apple_wdt_ops; + wdt->wdd.info = &apple_wdt_info; + wdt->wdd.max_timeout = U32_MAX / wdt->clk_rate; + wdt->wdd.timeout = APPLE_WDT_TIMEOUT_DEFAULT; + + wdt_ctrl = readl_relaxed(wdt->regs + APPLE_WDT_WD1_CTRL); + if (wdt_ctrl & APPLE_WDT_CTRL_RESET_EN) + set_bit(WDOG_HW_RUNNING, &wdt->wdd.status); + + watchdog_init_timeout(&wdt->wdd, 0, dev); + apple_wdt_set_timeout(&wdt->wdd, wdt->wdd.timeout); + watchdog_stop_on_unregister(&wdt->wdd); + watchdog_set_restart_priority(&wdt->wdd, 128); + + return devm_watchdog_register_device(dev, &wdt->wdd); +} + +static const struct of_device_id apple_wdt_of_match[] = { + { .compatible = "apple,wdt" }, + {}, +}; +MODULE_DEVICE_TABLE(of, apple_wdt_of_match); + +static struct platform_driver apple_wdt_driver = { + .driver = { + .name = "apple-watchdog", + .of_match_table = apple_wdt_of_match, + }, + .probe = apple_wdt_probe, +}; +module_platform_driver(apple_wdt_driver); + +MODULE_DESCRIPTION("Apple SoC watchdog driver"); +MODULE_AUTHOR("Sven Peter <sven@svenpeter.dev>"); +MODULE_LICENSE("Dual MIT/GPL"); |