// SPDX-License-Identifier: GPL-2.0 /* * coh901327_wdt.c * * Copyright (C) 2008-2009 ST-Ericsson AB * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core * Author: Linus Walleij <linus.walleij@stericsson.com> */ #include <linux/moduleparam.h> #include <linux/mod_devicetable.h> #include <linux/types.h> #include <linux/watchdog.h> #include <linux/interrupt.h> #include <linux/pm.h> #include <linux/platform_device.h> #include <linux/io.h> #include <linux/bitops.h> #include <linux/clk.h> #include <linux/delay.h> #include <linux/err.h> #define DRV_NAME "WDOG COH 901 327" /* * COH 901 327 register definitions */ /* WDOG_FEED Register 32bit (-/W) */ #define U300_WDOG_FR 0x00 #define U300_WDOG_FR_FEED_RESTART_TIMER 0xFEEDU /* WDOG_TIMEOUT Register 32bit (R/W) */ #define U300_WDOG_TR 0x04 #define U300_WDOG_TR_TIMEOUT_MASK 0x7FFFU /* WDOG_DISABLE1 Register 32bit (-/W) */ #define U300_WDOG_D1R 0x08 #define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER 0x2BADU /* WDOG_DISABLE2 Register 32bit (R/W) */ #define U300_WDOG_D2R 0x0C #define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER 0xCAFEU #define U300_WDOG_D2R_DISABLE_STATUS_DISABLED 0xDABEU #define U300_WDOG_D2R_DISABLE_STATUS_ENABLED 0x0000U /* WDOG_STATUS Register 32bit (R/W) */ #define U300_WDOG_SR 0x10 #define U300_WDOG_SR_STATUS_TIMED_OUT 0xCFE8U #define U300_WDOG_SR_STATUS_NORMAL 0x0000U #define U300_WDOG_SR_RESET_STATUS_RESET 0xE8B4U /* WDOG_COUNT Register 32bit (R/-) */ #define U300_WDOG_CR 0x14 #define U300_WDOG_CR_VALID_IND 0x8000U #define U300_WDOG_CR_VALID_STABLE 0x0000U #define U300_WDOG_CR_COUNT_VALUE_MASK 0x7FFFU /* WDOG_JTAGOVR Register 32bit (R/W) */ #define U300_WDOG_JOR 0x18 #define U300_WDOG_JOR_JTAG_MODE_IND 0x0002U #define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE 0x0001U /* WDOG_RESTART Register 32bit (-/W) */ #define U300_WDOG_RR 0x1C #define U300_WDOG_RR_RESTART_VALUE_RESUME 0xACEDU /* WDOG_IRQ_EVENT Register 32bit (R/W) */ #define U300_WDOG_IER 0x20 #define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND 0x0001U #define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE 0x0001U /* WDOG_IRQ_MASK Register 32bit (R/W) */ #define U300_WDOG_IMR 0x24 #define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE 0x0001U /* WDOG_IRQ_FORCE Register 32bit (R/W) */ #define U300_WDOG_IFR 0x28 #define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE 0x0001U /* Default timeout in seconds = 1 minute */ #define U300_WDOG_DEFAULT_TIMEOUT 60 static unsigned int margin; static int irq; static void __iomem *virtbase; static struct device *parent; static struct clk *clk; /* * Enabling and disabling functions. */ static void coh901327_enable(u16 timeout) { u16 val; unsigned long freq; unsigned long delay_ns; /* Restart timer if it is disabled */ val = readw(virtbase + U300_WDOG_D2R); if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED) writew(U300_WDOG_RR_RESTART_VALUE_RESUME, virtbase + U300_WDOG_RR); /* Acknowledge any pending interrupt so it doesn't just fire off */ writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE, virtbase + U300_WDOG_IER); /* * The interrupt is cleared in the 32 kHz clock domain. * Wait 3 32 kHz cycles for it to take effect */ freq = clk_get_rate(clk); delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */ delay_ns = 3 * delay_ns; /* Wait 3 cycles */ ndelay(delay_ns); /* Enable the watchdog interrupt */ writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR); /* Activate the watchdog timer */ writew(timeout, virtbase + U300_WDOG_TR); /* Start the watchdog timer */ writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR); /* * Extra read so that this change propagate in the watchdog. */ (void) readw(virtbase + U300_WDOG_CR); val = readw(virtbase + U300_WDOG_D2R); if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED) dev_err(parent, "%s(): watchdog not enabled! D2R value %04x\n", __func__, val); } static void coh901327_disable(void) { u16 val; /* Disable the watchdog interrupt if it is active */ writew(0x0000U, virtbase + U300_WDOG_IMR); /* If the watchdog is currently enabled, attempt to disable it */ val = readw(virtbase + U300_WDOG_D2R); if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) { writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER, virtbase + U300_WDOG_D1R); writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER, virtbase + U300_WDOG_D2R); /* Write this twice (else problems occur) */ writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER, virtbase + U300_WDOG_D2R); } val = readw(virtbase + U300_WDOG_D2R); if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) dev_err(parent, "%s(): watchdog not disabled! D2R value %04x\n", __func__, val); } static int coh901327_start(struct watchdog_device *wdt_dev) { coh901327_enable(wdt_dev->timeout * 100); return 0; } static int coh901327_stop(struct watchdog_device *wdt_dev) { coh901327_disable(); return 0; } static int coh901327_ping(struct watchdog_device *wdd) { /* Feed the watchdog */ writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR); return 0; } static int coh901327_settimeout(struct watchdog_device *wdt_dev, unsigned int time) { wdt_dev->timeout = time; /* Set new timeout value */ writew(time * 100, virtbase + U300_WDOG_TR); /* Feed the dog */ writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR); return 0; } static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev) { u16 val; /* Read repeatedly until the value is stable! */ val = readw(virtbase + U300_WDOG_CR); while (val & U300_WDOG_CR_VALID_IND) val = readw(virtbase + U300_WDOG_CR); val &= U300_WDOG_CR_COUNT_VALUE_MASK; if (val != 0) val /= 100; return val; } /* * This interrupt occurs 10 ms before the watchdog WILL bark. */ static irqreturn_t coh901327_interrupt(int irq, void *data) { u16 val; /* * Ack IRQ? If this occurs we're FUBAR anyway, so * just acknowledge, disable the interrupt and await the imminent end. * If you at some point need a host of callbacks to be called * when the system is about to watchdog-reset, add them here! * * NOTE: on future versions of this IP-block, it will be possible * to prevent a watchdog reset by feeding the watchdog at this * point. */ val = readw(virtbase + U300_WDOG_IER); if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND) writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE, virtbase + U300_WDOG_IER); writew(0x0000U, virtbase + U300_WDOG_IMR); dev_crit(parent, "watchdog is barking!\n"); return IRQ_HANDLED; } static const struct watchdog_info coh901327_ident = { .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, .identity = DRV_NAME, }; static const struct watchdog_ops coh901327_ops = { .owner = THIS_MODULE, .start = coh901327_start, .stop = coh901327_stop, .ping = coh901327_ping, .set_timeout = coh901327_settimeout, .get_timeleft = coh901327_gettimeleft, }; static struct watchdog_device coh901327_wdt = { .info = &coh901327_ident, .ops = &coh901327_ops, /* * Max timeout is 327 since the 10ms * timeout register is max * 0x7FFF = 327670ms ~= 327s. */ .min_timeout = 1, .max_timeout = 327, .timeout = U300_WDOG_DEFAULT_TIMEOUT, }; static int __init coh901327_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; int ret; u16 val; parent = dev; virtbase = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(virtbase)) return PTR_ERR(virtbase); clk = clk_get(dev, NULL); if (IS_ERR(clk)) { ret = PTR_ERR(clk); dev_err(dev, "could not get clock\n"); return ret; } ret = clk_prepare_enable(clk); if (ret) { dev_err(dev, "could not prepare and enable clock\n"); goto out_no_clk_enable; } val = readw(virtbase + U300_WDOG_SR); switch (val) { case U300_WDOG_SR_STATUS_TIMED_OUT: dev_info(dev, "watchdog timed out since last chip reset!\n"); coh901327_wdt.bootstatus |= WDIOF_CARDRESET; /* Status will be cleared below */ break; case U300_WDOG_SR_STATUS_NORMAL: dev_info(dev, "in normal status, no timeouts have occurred.\n"); break; default: dev_info(dev, "contains an illegal status code (%08x)\n", val); break; } val = readw(virtbase + U300_WDOG_D2R); switch (val) { case U300_WDOG_D2R_DISABLE_STATUS_DISABLED: dev_info(dev, "currently disabled.\n"); break; case U300_WDOG_D2R_DISABLE_STATUS_ENABLED: dev_info(dev, "currently enabled! (disabling it now)\n"); coh901327_disable(); break; default: dev_err(dev, "contains an illegal enable/disable code (%08x)\n", val); break; } /* Reset the watchdog */ writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR); irq = platform_get_irq(pdev, 0); if (request_irq(irq, coh901327_interrupt, 0, DRV_NAME " Bark", pdev)) { ret = -EIO; goto out_no_irq; } watchdog_init_timeout(&coh901327_wdt, margin, dev); coh901327_wdt.parent = dev; ret = watchdog_register_device(&coh901327_wdt); if (ret) goto out_no_wdog; dev_info(dev, "initialized. (timeout=%d sec)\n", coh901327_wdt.timeout); return 0; out_no_wdog: free_irq(irq, pdev); out_no_irq: clk_disable_unprepare(clk); out_no_clk_enable: clk_put(clk); return ret; } #ifdef CONFIG_PM static u16 wdogenablestore; static u16 irqmaskstore; static int coh901327_suspend(struct platform_device *pdev, pm_message_t state) { irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U; wdogenablestore = readw(virtbase + U300_WDOG_D2R); /* If watchdog is on, disable it here and now */ if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) coh901327_disable(); return 0; } static int coh901327_resume(struct platform_device *pdev) { /* Restore the watchdog interrupt */ writew(irqmaskstore, virtbase + U300_WDOG_IMR); if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) { /* Restart the watchdog timer */ writew(U300_WDOG_RR_RESTART_VALUE_RESUME, virtbase + U300_WDOG_RR); writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR); } return 0; } #else #define coh901327_suspend NULL #define coh901327_resume NULL #endif /* * Mistreating the watchdog is the only way to perform a software reset of the * system on EMP platforms. So we implement this and export a symbol for it. */ void coh901327_watchdog_reset(void) { /* Enable even if on JTAG too */ writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE, virtbase + U300_WDOG_JOR); /* * Timeout = 5s, we have to wait for the watchdog reset to * actually take place: the watchdog will be reloaded with the * default value immediately, so we HAVE to reboot and get back * into the kernel in 30s, or the device will reboot again! * The boot loader will typically deactivate the watchdog, so we * need time enough for the boot loader to get to the point of * deactivating the watchdog before it is shut down by it. * * NOTE: on future versions of the watchdog, this restriction is * gone: the watchdog will be reloaded with a default value (1 min) * instead of last value, and you can conveniently set the watchdog * timeout to 10ms (value = 1) without any problems. */ coh901327_enable(500); /* Return and await doom */ } static const struct of_device_id coh901327_dt_match[] = { { .compatible = "stericsson,coh901327" }, {}, }; static struct platform_driver coh901327_driver = { .driver = { .name = "coh901327_wdog", .of_match_table = coh901327_dt_match, .suppress_bind_attrs = true, }, .suspend = coh901327_suspend, .resume = coh901327_resume, }; builtin_platform_driver_probe(coh901327_driver, coh901327_probe); /* not really modular, but ... */ module_param(margin, uint, 0); MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");