diff options
Diffstat (limited to 'drivers/watchdog/realtek_otto_wdt.c')
| -rw-r--r-- | drivers/watchdog/realtek_otto_wdt.c | 372 |
1 files changed, 372 insertions, 0 deletions
diff --git a/drivers/watchdog/realtek_otto_wdt.c b/drivers/watchdog/realtek_otto_wdt.c new file mode 100644 index 000000000..2c30ddd57 --- /dev/null +++ b/drivers/watchdog/realtek_otto_wdt.c @@ -0,0 +1,372 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * Realtek Otto MIPS platform watchdog + * + * Watchdog timer that will reset the system after timeout, using the selected + * reset mode. + * + * Counter scaling and timeouts: + * - Base prescale of (2 << 25), providing tick duration T_0: 168ms @ 200MHz + * - PRESCALE: logarithmic prescaler adding a factor of {1, 2, 4, 8} + * - Phase 1: Times out after (PHASE1 + 1) × PRESCALE × T_0 + * Generates an interrupt, WDT cannot be stopped after phase 1 + * - Phase 2: starts after phase 1, times out after (PHASE2 + 1) × PRESCALE × T_0 + * Resets the system according to RST_MODE + */ + +#include <linux/bits.h> +#include <linux/bitfield.h> +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/math.h> +#include <linux/minmax.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/platform_device.h> +#include <linux/property.h> +#include <linux/reboot.h> +#include <linux/watchdog.h> + +#define OTTO_WDT_REG_CNTR 0x0 +#define OTTO_WDT_CNTR_PING BIT(31) + +#define OTTO_WDT_REG_INTR 0x4 +#define OTTO_WDT_INTR_PHASE_1 BIT(31) +#define OTTO_WDT_INTR_PHASE_2 BIT(30) + +#define OTTO_WDT_REG_CTRL 0x8 +#define OTTO_WDT_CTRL_ENABLE BIT(31) +#define OTTO_WDT_CTRL_PRESCALE GENMASK(30, 29) +#define OTTO_WDT_CTRL_PHASE1 GENMASK(26, 22) +#define OTTO_WDT_CTRL_PHASE2 GENMASK(19, 15) +#define OTTO_WDT_CTRL_RST_MODE GENMASK(1, 0) +#define OTTO_WDT_MODE_SOC 0 +#define OTTO_WDT_MODE_CPU 1 +#define OTTO_WDT_MODE_SOFTWARE 2 +#define OTTO_WDT_CTRL_DEFAULT OTTO_WDT_MODE_CPU + +#define OTTO_WDT_PRESCALE_MAX 3 + +/* + * One higher than the max values contained in PHASE{1,2}, since a value of 0 + * corresponds to one tick. + */ +#define OTTO_WDT_PHASE_TICKS_MAX 32 + +/* + * The maximum reset delay is actually 2×32 ticks, but that would require large + * pretimeout values for timeouts longer than 32 ticks. Limit the maximum timeout + * to 32 + 1 to ensure small pretimeout values can be configured as expected. + */ +#define OTTO_WDT_TIMEOUT_TICKS_MAX (OTTO_WDT_PHASE_TICKS_MAX + 1) + +struct otto_wdt_ctrl { + struct watchdog_device wdev; + struct device *dev; + void __iomem *base; + unsigned int clk_rate_khz; + int irq_phase1; +}; + +static int otto_wdt_start(struct watchdog_device *wdev) +{ + struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev); + u32 v; + + v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL); + v |= OTTO_WDT_CTRL_ENABLE; + iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL); + + return 0; +} + +static int otto_wdt_stop(struct watchdog_device *wdev) +{ + struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev); + u32 v; + + v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL); + v &= ~OTTO_WDT_CTRL_ENABLE; + iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL); + + return 0; +} + +static int otto_wdt_ping(struct watchdog_device *wdev) +{ + struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev); + + iowrite32(OTTO_WDT_CNTR_PING, ctrl->base + OTTO_WDT_REG_CNTR); + + return 0; +} + +static int otto_wdt_tick_ms(struct otto_wdt_ctrl *ctrl, int prescale) +{ + return DIV_ROUND_CLOSEST(1 << (25 + prescale), ctrl->clk_rate_khz); +} + +/* + * The timer asserts the PHASE1/PHASE2 IRQs when the number of ticks exceeds + * the value stored in those fields. This means each phase will run for at least + * one tick, so small values need to be clamped to correctly reflect the timeout. + */ +static inline unsigned int div_round_ticks(unsigned int val, unsigned int tick_duration, + unsigned int min_ticks) +{ + return max(min_ticks, DIV_ROUND_UP(val, tick_duration)); +} + +static int otto_wdt_determine_timeouts(struct watchdog_device *wdev, unsigned int timeout, + unsigned int pretimeout) +{ + struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev); + unsigned int pretimeout_ms = pretimeout * 1000; + unsigned int timeout_ms = timeout * 1000; + unsigned int prescale_next = 0; + unsigned int phase1_ticks; + unsigned int phase2_ticks; + unsigned int total_ticks; + unsigned int prescale; + unsigned int tick_ms; + u32 v; + + do { + prescale = prescale_next; + if (prescale > OTTO_WDT_PRESCALE_MAX) + return -EINVAL; + + tick_ms = otto_wdt_tick_ms(ctrl, prescale); + total_ticks = div_round_ticks(timeout_ms, tick_ms, 2); + phase1_ticks = div_round_ticks(timeout_ms - pretimeout_ms, tick_ms, 1); + phase2_ticks = total_ticks - phase1_ticks; + + prescale_next++; + } while (phase1_ticks > OTTO_WDT_PHASE_TICKS_MAX + || phase2_ticks > OTTO_WDT_PHASE_TICKS_MAX); + + v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL); + + v &= ~(OTTO_WDT_CTRL_PRESCALE | OTTO_WDT_CTRL_PHASE1 | OTTO_WDT_CTRL_PHASE2); + v |= FIELD_PREP(OTTO_WDT_CTRL_PHASE1, phase1_ticks - 1); + v |= FIELD_PREP(OTTO_WDT_CTRL_PHASE2, phase2_ticks - 1); + v |= FIELD_PREP(OTTO_WDT_CTRL_PRESCALE, prescale); + + iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL); + + timeout_ms = total_ticks * tick_ms; + ctrl->wdev.timeout = timeout_ms / 1000; + + pretimeout_ms = phase2_ticks * tick_ms; + ctrl->wdev.pretimeout = pretimeout_ms / 1000; + + return 0; +} + +static int otto_wdt_set_timeout(struct watchdog_device *wdev, unsigned int val) +{ + return otto_wdt_determine_timeouts(wdev, val, min(wdev->pretimeout, val - 1)); +} + +static int otto_wdt_set_pretimeout(struct watchdog_device *wdev, unsigned int val) +{ + return otto_wdt_determine_timeouts(wdev, wdev->timeout, val); +} + +static int otto_wdt_restart(struct watchdog_device *wdev, unsigned long reboot_mode, + void *data) +{ + struct otto_wdt_ctrl *ctrl = watchdog_get_drvdata(wdev); + u32 reset_mode; + u32 v; + + disable_irq(ctrl->irq_phase1); + + switch (reboot_mode) { + case REBOOT_SOFT: + reset_mode = OTTO_WDT_MODE_SOFTWARE; + break; + case REBOOT_WARM: + reset_mode = OTTO_WDT_MODE_CPU; + break; + default: + reset_mode = OTTO_WDT_MODE_SOC; + break; + } + + /* Configure for shortest timeout and wait for reset to occur */ + v = FIELD_PREP(OTTO_WDT_CTRL_RST_MODE, reset_mode) | OTTO_WDT_CTRL_ENABLE; + iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL); + + mdelay(3 * otto_wdt_tick_ms(ctrl, 0)); + + return 0; +} + +static irqreturn_t otto_wdt_phase1_isr(int irq, void *dev_id) +{ + struct otto_wdt_ctrl *ctrl = dev_id; + + iowrite32(OTTO_WDT_INTR_PHASE_1, ctrl->base + OTTO_WDT_REG_INTR); + dev_crit(ctrl->dev, "phase 1 timeout\n"); + watchdog_notify_pretimeout(&ctrl->wdev); + + return IRQ_HANDLED; +} + +static const struct watchdog_ops otto_wdt_ops = { + .owner = THIS_MODULE, + .start = otto_wdt_start, + .stop = otto_wdt_stop, + .ping = otto_wdt_ping, + .set_timeout = otto_wdt_set_timeout, + .set_pretimeout = otto_wdt_set_pretimeout, + .restart = otto_wdt_restart, +}; + +static const struct watchdog_info otto_wdt_info = { + .identity = "Realtek Otto watchdog timer", + .options = WDIOF_KEEPALIVEPING | + WDIOF_MAGICCLOSE | + WDIOF_SETTIMEOUT | + WDIOF_PRETIMEOUT, +}; + +static int otto_wdt_probe_clk(struct otto_wdt_ctrl *ctrl) +{ + struct clk *clk; + + clk = devm_clk_get_enabled(ctrl->dev, NULL); + if (IS_ERR(clk)) + return dev_err_probe(ctrl->dev, PTR_ERR(clk), "Failed to get clock\n"); + + ctrl->clk_rate_khz = clk_get_rate(clk) / 1000; + if (ctrl->clk_rate_khz == 0) + return dev_err_probe(ctrl->dev, -ENXIO, "Failed to get clock rate\n"); + + return 0; +} + +static int otto_wdt_probe_reset_mode(struct otto_wdt_ctrl *ctrl) +{ + static const char *mode_property = "realtek,reset-mode"; + const struct fwnode_handle *node = ctrl->dev->fwnode; + int mode_count; + u32 mode; + u32 v; + + if (!node) + return -ENXIO; + + mode_count = fwnode_property_string_array_count(node, mode_property); + if (mode_count < 0) + return mode_count; + else if (mode_count == 0) + return 0; + else if (mode_count != 1) + return -EINVAL; + + if (fwnode_property_match_string(node, mode_property, "soc") == 0) + mode = OTTO_WDT_MODE_SOC; + else if (fwnode_property_match_string(node, mode_property, "cpu") == 0) + mode = OTTO_WDT_MODE_CPU; + else if (fwnode_property_match_string(node, mode_property, "software") == 0) + mode = OTTO_WDT_MODE_SOFTWARE; + else + return -EINVAL; + + v = ioread32(ctrl->base + OTTO_WDT_REG_CTRL); + v &= ~OTTO_WDT_CTRL_RST_MODE; + v |= FIELD_PREP(OTTO_WDT_CTRL_RST_MODE, mode); + iowrite32(v, ctrl->base + OTTO_WDT_REG_CTRL); + + return 0; +} + +static int otto_wdt_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct otto_wdt_ctrl *ctrl; + unsigned int max_tick_ms; + int ret; + + ctrl = devm_kzalloc(dev, sizeof(*ctrl), GFP_KERNEL); + if (!ctrl) + return -ENOMEM; + + ctrl->dev = dev; + ctrl->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(ctrl->base)) + return PTR_ERR(ctrl->base); + + /* Clear any old interrupts and reset initial state */ + iowrite32(OTTO_WDT_INTR_PHASE_1 | OTTO_WDT_INTR_PHASE_2, + ctrl->base + OTTO_WDT_REG_INTR); + iowrite32(OTTO_WDT_CTRL_DEFAULT, ctrl->base + OTTO_WDT_REG_CTRL); + + ret = otto_wdt_probe_clk(ctrl); + if (ret) + return ret; + + ctrl->irq_phase1 = platform_get_irq_byname(pdev, "phase1"); + if (ctrl->irq_phase1 < 0) + return ctrl->irq_phase1; + + ret = devm_request_irq(dev, ctrl->irq_phase1, otto_wdt_phase1_isr, 0, + "realtek-otto-wdt", ctrl); + if (ret) + return dev_err_probe(dev, ret, "Failed to get IRQ for phase1\n"); + + ret = otto_wdt_probe_reset_mode(ctrl); + if (ret) + return dev_err_probe(dev, ret, "Invalid reset mode specified\n"); + + ctrl->wdev.parent = dev; + ctrl->wdev.info = &otto_wdt_info; + ctrl->wdev.ops = &otto_wdt_ops; + + /* + * Since pretimeout cannot be disabled, min. timeout is twice the + * subsystem resolution. Max. timeout is ca. 43s at a bus clock of 200MHz. + */ + ctrl->wdev.min_timeout = 2; + max_tick_ms = otto_wdt_tick_ms(ctrl, OTTO_WDT_PRESCALE_MAX); + ctrl->wdev.max_hw_heartbeat_ms = max_tick_ms * OTTO_WDT_TIMEOUT_TICKS_MAX; + ctrl->wdev.timeout = min(30U, ctrl->wdev.max_hw_heartbeat_ms / 1000); + + watchdog_set_drvdata(&ctrl->wdev, ctrl); + watchdog_init_timeout(&ctrl->wdev, 0, dev); + watchdog_stop_on_reboot(&ctrl->wdev); + watchdog_set_restart_priority(&ctrl->wdev, 128); + + ret = otto_wdt_determine_timeouts(&ctrl->wdev, ctrl->wdev.timeout, 1); + if (ret) + return dev_err_probe(dev, ret, "Failed to set timeout\n"); + + return devm_watchdog_register_device(dev, &ctrl->wdev); +} + +static const struct of_device_id otto_wdt_ids[] = { + { .compatible = "realtek,rtl8380-wdt" }, + { .compatible = "realtek,rtl8390-wdt" }, + { .compatible = "realtek,rtl9300-wdt" }, + { .compatible = "realtek,rtl9310-wdt" }, + { } +}; +MODULE_DEVICE_TABLE(of, otto_wdt_ids); + +static struct platform_driver otto_wdt_driver = { + .probe = otto_wdt_probe, + .driver = { + .name = "realtek-otto-watchdog", + .of_match_table = otto_wdt_ids, + }, +}; +module_platform_driver(otto_wdt_driver); + +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Sander Vanheule <sander@svanheule.net>"); +MODULE_DESCRIPTION("Realtek Otto watchdog timer driver"); |