diff options
Diffstat (limited to 'drivers/watchdog/cadence_wdt.c')
| -rw-r--r-- | drivers/watchdog/cadence_wdt.c | 516 |
1 files changed, 516 insertions, 0 deletions
diff --git a/drivers/watchdog/cadence_wdt.c b/drivers/watchdog/cadence_wdt.c new file mode 100644 index 0000000..5927c0a --- /dev/null +++ b/drivers/watchdog/cadence_wdt.c @@ -0,0 +1,516 @@ +/* + * Cadence WDT driver - Used by Xilinx Zynq + * + * Copyright (C) 2010 - 2014 Xilinx, Inc. + * + * 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/clk.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/irq.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/reboot.h> +#include <linux/watchdog.h> + +#define CDNS_WDT_DEFAULT_TIMEOUT 10 +/* Supports 1 - 516 sec */ +#define CDNS_WDT_MIN_TIMEOUT 1 +#define CDNS_WDT_MAX_TIMEOUT 516 + +/* Restart key */ +#define CDNS_WDT_RESTART_KEY 0x00001999 + +/* Counter register access key */ +#define CDNS_WDT_REGISTER_ACCESS_KEY 0x00920000 + +/* Counter value divisor */ +#define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000 + +/* Clock prescaler value and selection */ +#define CDNS_WDT_PRESCALE_64 64 +#define CDNS_WDT_PRESCALE_512 512 +#define CDNS_WDT_PRESCALE_4096 4096 +#define CDNS_WDT_PRESCALE_SELECT_64 1 +#define CDNS_WDT_PRESCALE_SELECT_512 2 +#define CDNS_WDT_PRESCALE_SELECT_4096 3 + +/* Input clock frequency */ +#define CDNS_WDT_CLK_10MHZ 10000000 +#define CDNS_WDT_CLK_75MHZ 75000000 + +/* Counter maximum value */ +#define CDNS_WDT_COUNTER_MAX 0xFFF + +static int wdt_timeout = CDNS_WDT_DEFAULT_TIMEOUT; +static int nowayout = WATCHDOG_NOWAYOUT; + +module_param(wdt_timeout, int, 0); +MODULE_PARM_DESC(wdt_timeout, + "Watchdog time in seconds. (default=" + __MODULE_STRING(CDNS_WDT_DEFAULT_TIMEOUT) ")"); + +module_param(nowayout, int, 0); +MODULE_PARM_DESC(nowayout, + "Watchdog cannot be stopped once started (default=" + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); + +/** + * struct cdns_wdt - Watchdog device structure + * @regs: baseaddress of device + * @rst: reset flag + * @clk: struct clk * of a clock source + * @prescaler: for saving prescaler value + * @ctrl_clksel: counter clock prescaler selection + * @io_lock: spinlock for IO register access + * @cdns_wdt_device: watchdog device structure + * @cdns_wdt_notifier: notifier structure + * + * Structure containing parameters specific to cadence watchdog. + */ +struct cdns_wdt { + void __iomem *regs; + bool rst; + struct clk *clk; + u32 prescaler; + u32 ctrl_clksel; + spinlock_t io_lock; + struct watchdog_device cdns_wdt_device; + struct notifier_block cdns_wdt_notifier; +}; + +/* Write access to Registers */ +static inline void cdns_wdt_writereg(struct cdns_wdt *wdt, u32 offset, u32 val) +{ + writel_relaxed(val, wdt->regs + offset); +} + +/*************************Register Map**************************************/ + +/* Register Offsets for the WDT */ +#define CDNS_WDT_ZMR_OFFSET 0x0 /* Zero Mode Register */ +#define CDNS_WDT_CCR_OFFSET 0x4 /* Counter Control Register */ +#define CDNS_WDT_RESTART_OFFSET 0x8 /* Restart Register */ +#define CDNS_WDT_SR_OFFSET 0xC /* Status Register */ + +/* + * Zero Mode Register - This register controls how the time out is indicated + * and also contains the access code to allow writes to the register (0xABC). + */ +#define CDNS_WDT_ZMR_WDEN_MASK 0x00000001 /* Enable the WDT */ +#define CDNS_WDT_ZMR_RSTEN_MASK 0x00000002 /* Enable the reset output */ +#define CDNS_WDT_ZMR_IRQEN_MASK 0x00000004 /* Enable IRQ output */ +#define CDNS_WDT_ZMR_RSTLEN_16 0x00000030 /* Reset pulse of 16 pclk cycles */ +#define CDNS_WDT_ZMR_ZKEY_VAL 0x00ABC000 /* Access key, 0xABC << 12 */ +/* + * Counter Control register - This register controls how fast the timer runs + * and the reset value and also contains the access code to allow writes to + * the register. + */ +#define CDNS_WDT_CCR_CRV_MASK 0x00003FFC /* Counter reset value */ + +/** + * cdns_wdt_stop - Stop the watchdog. + * + * @wdd: watchdog device + * + * Read the contents of the ZMR register, clear the WDEN bit + * in the register and set the access key for successful write. + * + * Return: always 0 + */ +static int cdns_wdt_stop(struct watchdog_device *wdd) +{ + struct cdns_wdt *wdt = watchdog_get_drvdata(wdd); + + spin_lock(&wdt->io_lock); + cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET, + CDNS_WDT_ZMR_ZKEY_VAL & (~CDNS_WDT_ZMR_WDEN_MASK)); + spin_unlock(&wdt->io_lock); + + return 0; +} + +/** + * cdns_wdt_reload - Reload the watchdog timer (i.e. pat the watchdog). + * + * @wdd: watchdog device + * + * Write the restart key value (0x00001999) to the restart register. + * + * Return: always 0 + */ +static int cdns_wdt_reload(struct watchdog_device *wdd) +{ + struct cdns_wdt *wdt = watchdog_get_drvdata(wdd); + + spin_lock(&wdt->io_lock); + cdns_wdt_writereg(wdt, CDNS_WDT_RESTART_OFFSET, + CDNS_WDT_RESTART_KEY); + spin_unlock(&wdt->io_lock); + + return 0; +} + +/** + * cdns_wdt_start - Enable and start the watchdog. + * + * @wdd: watchdog device + * + * The counter value is calculated according to the formula: + * calculated count = (timeout * clock) / prescaler + 1. + * The calculated count is divided by 0x1000 to obtain the field value + * to write to counter control register. + * Clears the contents of prescaler and counter reset value. Sets the + * prescaler to 4096 and the calculated count and access key + * to write to CCR Register. + * Sets the WDT (WDEN bit) and either the Reset signal(RSTEN bit) + * or Interrupt signal(IRQEN) with a specified cycles and the access + * key to write to ZMR Register. + * + * Return: always 0 + */ +static int cdns_wdt_start(struct watchdog_device *wdd) +{ + struct cdns_wdt *wdt = watchdog_get_drvdata(wdd); + unsigned int data = 0; + unsigned short count; + unsigned long clock_f = clk_get_rate(wdt->clk); + + /* + * Counter value divisor to obtain the value of + * counter reset to be written to control register. + */ + count = (wdd->timeout * (clock_f / wdt->prescaler)) / + CDNS_WDT_COUNTER_VALUE_DIVISOR + 1; + + if (count > CDNS_WDT_COUNTER_MAX) + count = CDNS_WDT_COUNTER_MAX; + + spin_lock(&wdt->io_lock); + cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET, + CDNS_WDT_ZMR_ZKEY_VAL); + + count = (count << 2) & CDNS_WDT_CCR_CRV_MASK; + + /* Write counter access key first to be able write to register */ + data = count | CDNS_WDT_REGISTER_ACCESS_KEY | wdt->ctrl_clksel; + cdns_wdt_writereg(wdt, CDNS_WDT_CCR_OFFSET, data); + data = CDNS_WDT_ZMR_WDEN_MASK | CDNS_WDT_ZMR_RSTLEN_16 | + CDNS_WDT_ZMR_ZKEY_VAL; + + /* Reset on timeout if specified in device tree. */ + if (wdt->rst) { + data |= CDNS_WDT_ZMR_RSTEN_MASK; + data &= ~CDNS_WDT_ZMR_IRQEN_MASK; + } else { + data &= ~CDNS_WDT_ZMR_RSTEN_MASK; + data |= CDNS_WDT_ZMR_IRQEN_MASK; + } + cdns_wdt_writereg(wdt, CDNS_WDT_ZMR_OFFSET, data); + cdns_wdt_writereg(wdt, CDNS_WDT_RESTART_OFFSET, + CDNS_WDT_RESTART_KEY); + spin_unlock(&wdt->io_lock); + + return 0; +} + +/** + * cdns_wdt_settimeout - Set a new timeout value for the watchdog device. + * + * @wdd: watchdog device + * @new_time: new timeout value that needs to be set + * Return: 0 on success + * + * Update the watchdog_device timeout with new value which is used when + * cdns_wdt_start is called. + */ +static int cdns_wdt_settimeout(struct watchdog_device *wdd, + unsigned int new_time) +{ + wdd->timeout = new_time; + + return cdns_wdt_start(wdd); +} + +/** + * cdns_wdt_irq_handler - Notifies of watchdog timeout. + * + * @irq: interrupt number + * @dev_id: pointer to a platform device structure + * Return: IRQ_HANDLED + * + * The handler is invoked when the watchdog times out and a + * reset on timeout has not been enabled. + */ +static irqreturn_t cdns_wdt_irq_handler(int irq, void *dev_id) +{ + struct platform_device *pdev = dev_id; + + dev_info(&pdev->dev, + "Watchdog timed out. Internal reset not enabled\n"); + + return IRQ_HANDLED; +} + +/* + * Info structure used to indicate the features supported by the device + * to the upper layers. This is defined in watchdog.h header file. + */ +static struct watchdog_info cdns_wdt_info = { + .identity = "cdns_wdt watchdog", + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | + WDIOF_MAGICCLOSE, +}; + +/* Watchdog Core Ops */ +static struct watchdog_ops cdns_wdt_ops = { + .owner = THIS_MODULE, + .start = cdns_wdt_start, + .stop = cdns_wdt_stop, + .ping = cdns_wdt_reload, + .set_timeout = cdns_wdt_settimeout, +}; + +/** + * cdns_wdt_notify_sys - Notifier for reboot or shutdown. + * + * @this: handle to notifier block + * @code: turn off indicator + * @unused: unused + * Return: NOTIFY_DONE + * + * This notifier is invoked whenever the system reboot or shutdown occur + * because we need to disable the WDT before system goes down as WDT might + * reset on the next boot. + */ +static int cdns_wdt_notify_sys(struct notifier_block *this, unsigned long code, + void *unused) +{ + struct cdns_wdt *wdt = container_of(this, struct cdns_wdt, + cdns_wdt_notifier); + if (code == SYS_DOWN || code == SYS_HALT) + cdns_wdt_stop(&wdt->cdns_wdt_device); + + return NOTIFY_DONE; +} + +/************************Platform Operations*****************************/ +/** + * cdns_wdt_probe - Probe call for the device. + * + * @pdev: handle to the platform device structure. + * Return: 0 on success, negative error otherwise. + * + * It does all the memory allocation and registration for the device. + */ +static int cdns_wdt_probe(struct platform_device *pdev) +{ + struct resource *res; + int ret, irq; + unsigned long clock_f; + struct cdns_wdt *wdt; + struct watchdog_device *cdns_wdt_device; + + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); + if (!wdt) + return -ENOMEM; + + cdns_wdt_device = &wdt->cdns_wdt_device; + cdns_wdt_device->info = &cdns_wdt_info; + cdns_wdt_device->ops = &cdns_wdt_ops; + cdns_wdt_device->timeout = CDNS_WDT_DEFAULT_TIMEOUT; + cdns_wdt_device->min_timeout = CDNS_WDT_MIN_TIMEOUT; + cdns_wdt_device->max_timeout = CDNS_WDT_MAX_TIMEOUT; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + wdt->regs = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(wdt->regs)) + return PTR_ERR(wdt->regs); + + /* Register the interrupt */ + wdt->rst = of_property_read_bool(pdev->dev.of_node, "reset-on-timeout"); + irq = platform_get_irq(pdev, 0); + if (!wdt->rst && irq >= 0) { + ret = devm_request_irq(&pdev->dev, irq, cdns_wdt_irq_handler, 0, + pdev->name, pdev); + if (ret) { + dev_err(&pdev->dev, + "cannot register interrupt handler err=%d\n", + ret); + return ret; + } + } + + /* Initialize the members of cdns_wdt structure */ + cdns_wdt_device->parent = &pdev->dev; + + ret = watchdog_init_timeout(cdns_wdt_device, wdt_timeout, &pdev->dev); + if (ret) { + dev_err(&pdev->dev, "unable to set timeout value\n"); + return ret; + } + + watchdog_set_nowayout(cdns_wdt_device, nowayout); + watchdog_set_drvdata(cdns_wdt_device, wdt); + + wdt->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(wdt->clk)) { + dev_err(&pdev->dev, "input clock not found\n"); + ret = PTR_ERR(wdt->clk); + return ret; + } + + ret = clk_prepare_enable(wdt->clk); + if (ret) { + dev_err(&pdev->dev, "unable to enable clock\n"); + return ret; + } + + clock_f = clk_get_rate(wdt->clk); + if (clock_f <= CDNS_WDT_CLK_75MHZ) { + wdt->prescaler = CDNS_WDT_PRESCALE_512; + wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512; + } else { + wdt->prescaler = CDNS_WDT_PRESCALE_4096; + wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_4096; + } + + spin_lock_init(&wdt->io_lock); + + wdt->cdns_wdt_notifier.notifier_call = &cdns_wdt_notify_sys; + ret = register_reboot_notifier(&wdt->cdns_wdt_notifier); + if (ret != 0) { + dev_err(&pdev->dev, "cannot register reboot notifier err=%d)\n", + ret); + goto err_clk_disable; + } + + ret = watchdog_register_device(cdns_wdt_device); + if (ret) { + dev_err(&pdev->dev, "Failed to register wdt device\n"); + goto err_clk_disable; + } + platform_set_drvdata(pdev, wdt); + + dev_dbg(&pdev->dev, "Xilinx Watchdog Timer at %p with timeout %ds%s\n", + wdt->regs, cdns_wdt_device->timeout, + nowayout ? ", nowayout" : ""); + + return 0; + +err_clk_disable: + clk_disable_unprepare(wdt->clk); + + return ret; +} + +/** + * cdns_wdt_remove - Probe call for the device. + * + * @pdev: handle to the platform device structure. + * Return: 0 on success, otherwise negative error. + * + * Unregister the device after releasing the resources. + */ +static int cdns_wdt_remove(struct platform_device *pdev) +{ + struct cdns_wdt *wdt = platform_get_drvdata(pdev); + + cdns_wdt_stop(&wdt->cdns_wdt_device); + watchdog_unregister_device(&wdt->cdns_wdt_device); + unregister_reboot_notifier(&wdt->cdns_wdt_notifier); + clk_disable_unprepare(wdt->clk); + + return 0; +} + +/** + * cdns_wdt_shutdown - Stop the device. + * + * @pdev: handle to the platform structure. + * + */ +static void cdns_wdt_shutdown(struct platform_device *pdev) +{ + struct cdns_wdt *wdt = platform_get_drvdata(pdev); + + cdns_wdt_stop(&wdt->cdns_wdt_device); + clk_disable_unprepare(wdt->clk); +} + +/** + * cdns_wdt_suspend - Stop the device. + * + * @dev: handle to the device structure. + * Return: 0 always. + */ +static int __maybe_unused cdns_wdt_suspend(struct device *dev) +{ + struct platform_device *pdev = container_of(dev, + struct platform_device, dev); + struct cdns_wdt *wdt = platform_get_drvdata(pdev); + + cdns_wdt_stop(&wdt->cdns_wdt_device); + clk_disable_unprepare(wdt->clk); + + return 0; +} + +/** + * cdns_wdt_resume - Resume the device. + * + * @dev: handle to the device structure. + * Return: 0 on success, errno otherwise. + */ +static int __maybe_unused cdns_wdt_resume(struct device *dev) +{ + int ret; + struct platform_device *pdev = container_of(dev, + struct platform_device, dev); + struct cdns_wdt *wdt = platform_get_drvdata(pdev); + + ret = clk_prepare_enable(wdt->clk); + if (ret) { + dev_err(dev, "unable to enable clock\n"); + return ret; + } + cdns_wdt_start(&wdt->cdns_wdt_device); + + return 0; +} + +static SIMPLE_DEV_PM_OPS(cdns_wdt_pm_ops, cdns_wdt_suspend, cdns_wdt_resume); + +static struct of_device_id cdns_wdt_of_match[] = { + { .compatible = "cdns,wdt-r1p2", }, + { /* end of table */ } +}; +MODULE_DEVICE_TABLE(of, cdns_wdt_of_match); + +/* Driver Structure */ +static struct platform_driver cdns_wdt_driver = { + .probe = cdns_wdt_probe, + .remove = cdns_wdt_remove, + .shutdown = cdns_wdt_shutdown, + .driver = { + .name = "cdns-wdt", + .owner = THIS_MODULE, + .of_match_table = cdns_wdt_of_match, + .pm = &cdns_wdt_pm_ops, + }, +}; + +module_platform_driver(cdns_wdt_driver); + +MODULE_AUTHOR("Xilinx, Inc."); +MODULE_DESCRIPTION("Watchdog driver for Cadence WDT"); +MODULE_LICENSE("GPL"); |
