diff options
Diffstat (limited to 'drivers/watchdog/aspeed_wdt.c')
| -rw-r--r-- | drivers/watchdog/aspeed_wdt.c | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c new file mode 100644 index 000000000..814041d4e --- /dev/null +++ b/drivers/watchdog/aspeed_wdt.c @@ -0,0 +1,353 @@ +/* + * Copyright 2016 IBM Corporation + * + * Joel Stanley <joel@jms.id.au> + * + * 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/delay.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> + +struct aspeed_wdt { + struct watchdog_device wdd; + void __iomem *base; + u32 ctrl; +}; + +struct aspeed_wdt_config { + u32 ext_pulse_width_mask; +}; + +static const struct aspeed_wdt_config ast2400_config = { + .ext_pulse_width_mask = 0xff, +}; + +static const struct aspeed_wdt_config ast2500_config = { + .ext_pulse_width_mask = 0xfffff, +}; + +static const struct of_device_id aspeed_wdt_of_table[] = { + { .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config }, + { .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config }, + { .compatible = "aspeed,ast2600-wdt", .data = &ast2500_config }, + { }, +}; +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_BOOT_SECONDARY BIT(7) +#define WDT_CTRL_RESET_MODE_SOC (0x00 << 5) +#define WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5) +#define WDT_CTRL_RESET_MODE_ARM_CPU (0x10 << 5) +#define WDT_CTRL_1MHZ_CLK BIT(4) +#define WDT_CTRL_WDT_EXT BIT(3) +#define WDT_CTRL_WDT_INTR BIT(2) +#define WDT_CTRL_RESET_SYSTEM BIT(1) +#define WDT_CTRL_ENABLE BIT(0) +#define WDT_TIMEOUT_STATUS 0x10 +#define WDT_TIMEOUT_STATUS_BOOT_SECONDARY BIT(1) + +/* + * WDT_RESET_WIDTH controls the characteristics of the external pulse (if + * enabled), specifically: + * + * * Pulse duration + * * Drive mode: push-pull vs open-drain + * * Polarity: Active high or active low + * + * Pulse duration configuration is available on both the AST2400 and AST2500, + * though the field changes between SoCs: + * + * AST2400: Bits 7:0 + * AST2500: Bits 19:0 + * + * This difference is captured in struct aspeed_wdt_config. + * + * The AST2500 exposes the drive mode and polarity options, but not in a + * regular fashion. For read purposes, bit 31 represents active high or low, + * and bit 30 represents push-pull or open-drain. With respect to write, magic + * values need to be written to the top byte to change the state of the drive + * mode and polarity bits. Any other value written to the top byte has no + * effect on the state of the drive mode or polarity bits. However, the pulse + * width value must be preserved (as desired) if written. + */ +#define WDT_RESET_WIDTH 0x18 +#define WDT_RESET_WIDTH_ACTIVE_HIGH BIT(31) +#define WDT_ACTIVE_HIGH_MAGIC (0xA5 << 24) +#define WDT_ACTIVE_LOW_MAGIC (0x5A << 24) +#define WDT_RESET_WIDTH_PUSH_PULL BIT(30) +#define WDT_PUSH_PULL_MAGIC (0xA8 << 24) +#define WDT_OPEN_DRAIN_MAGIC (0x8A << 24) + +#define WDT_RESTART_MAGIC 0x4755 + +/* 32 bits at 1MHz, in milliseconds */ +#define WDT_MAX_TIMEOUT_MS 4294967 +#define WDT_DEFAULT_TIMEOUT 30 +#define WDT_RATE_1MHZ 1000000 + +static struct aspeed_wdt *to_aspeed_wdt(struct watchdog_device *wdd) +{ + return container_of(wdd, struct aspeed_wdt, wdd); +} + +static void aspeed_wdt_enable(struct aspeed_wdt *wdt, int count) +{ + wdt->ctrl |= 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(wdt->ctrl, wdt->base + WDT_CTRL); +} + +static int aspeed_wdt_start(struct watchdog_device *wdd) +{ + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd); + + aspeed_wdt_enable(wdt, wdd->timeout * WDT_RATE_1MHZ); + + return 0; +} + +static int aspeed_wdt_stop(struct watchdog_device *wdd) +{ + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd); + + wdt->ctrl &= ~WDT_CTRL_ENABLE; + writel(wdt->ctrl, wdt->base + WDT_CTRL); + + return 0; +} + +static int aspeed_wdt_ping(struct watchdog_device *wdd) +{ + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd); + + writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART); + + return 0; +} + +static int aspeed_wdt_set_timeout(struct watchdog_device *wdd, + unsigned int timeout) +{ + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd); + u32 actual; + + wdd->timeout = timeout; + + actual = min(timeout, wdd->max_hw_heartbeat_ms / 1000); + + writel(actual * WDT_RATE_1MHZ, wdt->base + WDT_RELOAD_VALUE); + writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART); + + return 0; +} + +static int aspeed_wdt_restart(struct watchdog_device *wdd, + unsigned long action, void *data) +{ + struct aspeed_wdt *wdt = to_aspeed_wdt(wdd); + + wdt->ctrl &= ~WDT_CTRL_BOOT_SECONDARY; + aspeed_wdt_enable(wdt, 128 * WDT_RATE_1MHZ / 1000); + + mdelay(1000); + + return 0; +} + +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, + .restart = aspeed_wdt_restart, + .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_probe(struct platform_device *pdev) +{ + const struct aspeed_wdt_config *config; + const struct of_device_id *ofdid; + struct aspeed_wdt *wdt; + struct resource *res; + struct device_node *np; + const char *reset_type; + u32 duration; + u32 status; + 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->wdd.info = &aspeed_wdt_info; + wdt->wdd.ops = &aspeed_wdt_ops; + wdt->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS; + wdt->wdd.parent = &pdev->dev; + + wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT; + watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev); + + np = pdev->dev.of_node; + + ofdid = of_match_node(aspeed_wdt_of_table, np); + if (!ofdid) + return -EINVAL; + config = ofdid->data; + + /* + * On clock rates: + * - ast2400 wdt can run at PCLK, or 1MHz + * - ast2500 only runs at 1MHz, hard coding bit 4 to 1 + * - ast2600 always runs at 1MHz + * + * Set the ast2400 to run at 1MHz as it simplifies the driver. + */ + if (of_device_is_compatible(np, "aspeed,ast2400-wdt")) + wdt->ctrl = WDT_CTRL_1MHZ_CLK; + + /* + * Control reset on a per-device basis to ensure the + * host is not affected by a BMC reboot + */ + ret = of_property_read_string(np, "aspeed,reset-type", &reset_type); + if (ret) { + wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM; + } else { + if (!strcmp(reset_type, "cpu")) + wdt->ctrl |= WDT_CTRL_RESET_MODE_ARM_CPU | + WDT_CTRL_RESET_SYSTEM; + else if (!strcmp(reset_type, "soc")) + wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | + WDT_CTRL_RESET_SYSTEM; + else if (!strcmp(reset_type, "system")) + wdt->ctrl |= WDT_CTRL_RESET_MODE_FULL_CHIP | + WDT_CTRL_RESET_SYSTEM; + else if (strcmp(reset_type, "none")) + return -EINVAL; + } + if (of_property_read_bool(np, "aspeed,external-signal")) + wdt->ctrl |= WDT_CTRL_WDT_EXT; + if (of_property_read_bool(np, "aspeed,alt-boot")) + wdt->ctrl |= WDT_CTRL_BOOT_SECONDARY; + + if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE) { + /* + * The watchdog is running, but invoke aspeed_wdt_start() to + * write wdt->ctrl to WDT_CTRL to ensure the watchdog's + * configuration conforms to the driver's expectations. + * Primarily, ensure we're using the 1MHz clock source. + */ + aspeed_wdt_start(&wdt->wdd); + set_bit(WDOG_HW_RUNNING, &wdt->wdd.status); + } + + if ((of_device_is_compatible(np, "aspeed,ast2500-wdt")) || + (of_device_is_compatible(np, "aspeed,ast2600-wdt"))) { + u32 reg = readl(wdt->base + WDT_RESET_WIDTH); + + reg &= config->ext_pulse_width_mask; + if (of_property_read_bool(np, "aspeed,ext-push-pull")) + reg |= WDT_PUSH_PULL_MAGIC; + else + reg |= WDT_OPEN_DRAIN_MAGIC; + + writel(reg, wdt->base + WDT_RESET_WIDTH); + + reg &= config->ext_pulse_width_mask; + if (of_property_read_bool(np, "aspeed,ext-active-high")) + reg |= WDT_ACTIVE_HIGH_MAGIC; + else + reg |= WDT_ACTIVE_LOW_MAGIC; + + writel(reg, wdt->base + WDT_RESET_WIDTH); + } + + if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) { + u32 max_duration = config->ext_pulse_width_mask + 1; + + if (duration == 0 || duration > max_duration) { + dev_err(&pdev->dev, "Invalid pulse duration: %uus\n", + duration); + duration = max(1U, min(max_duration, duration)); + dev_info(&pdev->dev, "Pulse duration set to %uus\n", + duration); + } + + /* + * The watchdog is always configured with a 1MHz source, so + * there is no need to scale the microsecond value. However we + * need to offset it - from the datasheet: + * + * "This register decides the asserting duration of wdt_ext and + * wdt_rstarm signal. The default value is 0xFF. It means the + * default asserting duration of wdt_ext and wdt_rstarm is + * 256us." + * + * This implies a value of 0 gives a 1us pulse. + */ + writel(duration - 1, wdt->base + WDT_RESET_WIDTH); + } + + status = readl(wdt->base + WDT_TIMEOUT_STATUS); + if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) + wdt->wdd.bootstatus = WDIOF_CARDRESET; + + ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd); + if (ret) { + dev_err(&pdev->dev, "failed to register\n"); + return ret; + } + + return 0; +} + +static struct platform_driver aspeed_watchdog_driver = { + .probe = aspeed_wdt_probe, + .driver = { + .name = KBUILD_MODNAME, + .of_match_table = of_match_ptr(aspeed_wdt_of_table), + }, +}; + +static int __init aspeed_wdt_init(void) +{ + return platform_driver_register(&aspeed_watchdog_driver); +} +arch_initcall(aspeed_wdt_init); + +static void __exit aspeed_wdt_exit(void) +{ + platform_driver_unregister(&aspeed_watchdog_driver); +} +module_exit(aspeed_wdt_exit); + +MODULE_DESCRIPTION("Aspeed Watchdog Driver"); +MODULE_LICENSE("GPL"); |