// SPDX-License-Identifier: GPL-2.0 /* * Driver for STM32 Independent Watchdog * * Copyright (C) STMicroelectronics 2017 * Author: Yannick Fertre for STMicroelectronics. * * This driver is based on tegra_wdt.c * */ #include #include #include #include #include #include #include #include #include #include #include /* IWDG registers */ #define IWDG_KR 0x00 /* Key register */ #define IWDG_PR 0x04 /* Prescaler Register */ #define IWDG_RLR 0x08 /* ReLoad Register */ #define IWDG_SR 0x0C /* Status Register */ #define IWDG_WINR 0x10 /* Windows Register */ /* IWDG_KR register bit mask */ #define KR_KEY_RELOAD 0xAAAA /* reload counter enable */ #define KR_KEY_ENABLE 0xCCCC /* peripheral enable */ #define KR_KEY_EWA 0x5555 /* write access enable */ #define KR_KEY_DWA 0x0000 /* write access disable */ /* IWDG_PR register */ #define PR_SHIFT 2 #define PR_MIN BIT(PR_SHIFT) /* IWDG_RLR register values */ #define RLR_MIN 0x2 /* min value recommended */ #define RLR_MAX GENMASK(11, 0) /* max value of reload register */ /* IWDG_SR register bit mask */ #define SR_PVU BIT(0) /* Watchdog prescaler value update */ #define SR_RVU BIT(1) /* Watchdog counter reload value update */ /* set timeout to 100000 us */ #define TIMEOUT_US 100000 #define SLEEP_US 1000 struct stm32_iwdg_data { bool has_pclk; u32 max_prescaler; }; static const struct stm32_iwdg_data stm32_iwdg_data = { .has_pclk = false, .max_prescaler = 256, }; static const struct stm32_iwdg_data stm32mp1_iwdg_data = { .has_pclk = true, .max_prescaler = 1024, }; struct stm32_iwdg { struct watchdog_device wdd; const struct stm32_iwdg_data *data; void __iomem *regs; struct clk *clk_lsi; struct clk *clk_pclk; unsigned int rate; }; static inline u32 reg_read(void __iomem *base, u32 reg) { return readl_relaxed(base + reg); } static inline void reg_write(void __iomem *base, u32 reg, u32 val) { writel_relaxed(val, base + reg); } static int stm32_iwdg_start(struct watchdog_device *wdd) { struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); u32 tout, presc, iwdg_rlr, iwdg_pr, iwdg_sr; int ret; dev_dbg(wdd->parent, "%s\n", __func__); tout = clamp_t(unsigned int, wdd->timeout, wdd->min_timeout, wdd->max_hw_heartbeat_ms / 1000); presc = DIV_ROUND_UP(tout * wdt->rate, RLR_MAX + 1); /* The prescaler is align on power of 2 and start at 2 ^ PR_SHIFT. */ presc = roundup_pow_of_two(presc); iwdg_pr = presc <= 1 << PR_SHIFT ? 0 : ilog2(presc) - PR_SHIFT; iwdg_rlr = ((tout * wdt->rate) / presc) - 1; /* enable write access */ reg_write(wdt->regs, IWDG_KR, KR_KEY_EWA); /* set prescaler & reload registers */ reg_write(wdt->regs, IWDG_PR, iwdg_pr); reg_write(wdt->regs, IWDG_RLR, iwdg_rlr); reg_write(wdt->regs, IWDG_KR, KR_KEY_ENABLE); /* wait for the registers to be updated (max 100ms) */ ret = readl_relaxed_poll_timeout(wdt->regs + IWDG_SR, iwdg_sr, !(iwdg_sr & (SR_PVU | SR_RVU)), SLEEP_US, TIMEOUT_US); if (ret) { dev_err(wdd->parent, "Fail to set prescaler, reload regs\n"); return ret; } /* reload watchdog */ reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD); return 0; } static int stm32_iwdg_ping(struct watchdog_device *wdd) { struct stm32_iwdg *wdt = watchdog_get_drvdata(wdd); dev_dbg(wdd->parent, "%s\n", __func__); /* reload watchdog */ reg_write(wdt->regs, IWDG_KR, KR_KEY_RELOAD); return 0; } static int stm32_iwdg_set_timeout(struct watchdog_device *wdd, unsigned int timeout) { dev_dbg(wdd->parent, "%s timeout: %d sec\n", __func__, timeout); wdd->timeout = timeout; if (watchdog_active(wdd)) return stm32_iwdg_start(wdd); return 0; } static void stm32_clk_disable_unprepare(void *data) { clk_disable_unprepare(data); } static int stm32_iwdg_clk_init(struct platform_device *pdev, struct stm32_iwdg *wdt) { struct device *dev = &pdev->dev; u32 ret; wdt->clk_lsi = devm_clk_get(dev, "lsi"); if (IS_ERR(wdt->clk_lsi)) { if (PTR_ERR(wdt->clk_lsi) != -EPROBE_DEFER) dev_err(dev, "Unable to get lsi clock\n"); return PTR_ERR(wdt->clk_lsi); } /* optional peripheral clock */ if (wdt->data->has_pclk) { wdt->clk_pclk = devm_clk_get(dev, "pclk"); if (IS_ERR(wdt->clk_pclk)) { if (PTR_ERR(wdt->clk_pclk) != -EPROBE_DEFER) dev_err(dev, "Unable to get pclk clock\n"); return PTR_ERR(wdt->clk_pclk); } ret = clk_prepare_enable(wdt->clk_pclk); if (ret) { dev_err(dev, "Unable to prepare pclk clock\n"); return ret; } ret = devm_add_action_or_reset(dev, stm32_clk_disable_unprepare, wdt->clk_pclk); if (ret) return ret; } ret = clk_prepare_enable(wdt->clk_lsi); if (ret) { dev_err(dev, "Unable to prepare lsi clock\n"); return ret; } ret = devm_add_action_or_reset(dev, stm32_clk_disable_unprepare, wdt->clk_lsi); if (ret) return ret; wdt->rate = clk_get_rate(wdt->clk_lsi); return 0; } static const struct watchdog_info stm32_iwdg_info = { .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, .identity = "STM32 Independent Watchdog", }; static const struct watchdog_ops stm32_iwdg_ops = { .owner = THIS_MODULE, .start = stm32_iwdg_start, .ping = stm32_iwdg_ping, .set_timeout = stm32_iwdg_set_timeout, }; static const struct of_device_id stm32_iwdg_of_match[] = { { .compatible = "st,stm32-iwdg", .data = &stm32_iwdg_data }, { .compatible = "st,stm32mp1-iwdg", .data = &stm32mp1_iwdg_data }, { /* end node */ } }; MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match); static int stm32_iwdg_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct watchdog_device *wdd; struct stm32_iwdg *wdt; int ret; wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); if (!wdt) return -ENOMEM; wdt->data = of_device_get_match_data(&pdev->dev); if (!wdt->data) return -ENODEV; /* This is the timer base. */ wdt->regs = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(wdt->regs)) { dev_err(dev, "Could not get resource\n"); return PTR_ERR(wdt->regs); } ret = stm32_iwdg_clk_init(pdev, wdt); if (ret) return ret; /* Initialize struct watchdog_device. */ wdd = &wdt->wdd; wdd->parent = dev; wdd->info = &stm32_iwdg_info; wdd->ops = &stm32_iwdg_ops; wdd->min_timeout = DIV_ROUND_UP((RLR_MIN + 1) * PR_MIN, wdt->rate); wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler * 1000) / wdt->rate; watchdog_set_drvdata(wdd, wdt); watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT); watchdog_init_timeout(wdd, 0, dev); /* * In case of CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set * (Means U-Boot/bootloaders leaves the watchdog running) * When we get here we should make a decision to prevent * any side effects before user space daemon will take care of it. * The best option, taking into consideration that there is no * way to read values back from hardware, is to enforce watchdog * being run with deterministic values. */ if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) { ret = stm32_iwdg_start(wdd); if (ret) return ret; /* Make sure the watchdog is serviced */ set_bit(WDOG_HW_RUNNING, &wdd->status); } ret = devm_watchdog_register_device(dev, wdd); if (ret) return ret; platform_set_drvdata(pdev, wdt); return 0; } static struct platform_driver stm32_iwdg_driver = { .probe = stm32_iwdg_probe, .driver = { .name = "iwdg", .of_match_table = of_match_ptr(stm32_iwdg_of_match), }, }; module_platform_driver(stm32_iwdg_driver); MODULE_AUTHOR("Yannick Fertre "); MODULE_DESCRIPTION("STMicroelectronics STM32 Independent Watchdog Driver"); MODULE_LICENSE("GPL v2");