| // SPDX-License-Identifier: GPL-2.0+ |
| /* |
| * Cadence WDT driver - Used by Xilinx Zynq |
| * |
| * Copyright (C) 2010 - 2014 Xilinx, Inc. |
| * |
| */ |
| |
| #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/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; |
| static int nowayout = WATCHDOG_NOWAYOUT; |
| |
| module_param(wdt_timeout, int, 0644); |
| MODULE_PARM_DESC(wdt_timeout, |
| "Watchdog time in seconds. (default=" |
| __MODULE_STRING(CDNS_WDT_DEFAULT_TIMEOUT) ")"); |
| |
| module_param(nowayout, int, 0644); |
| 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 |
| * |
| * 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; |
| }; |
| |
| /* 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 const struct watchdog_info cdns_wdt_info = { |
| .identity = "cdns_wdt watchdog", |
| .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | |
| WDIOF_MAGICCLOSE, |
| }; |
| |
| /* Watchdog Core Ops */ |
| static const 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, |
| }; |
| |
| static void cdns_clk_disable_unprepare(void *data) |
| { |
| clk_disable_unprepare(data); |
| } |
| |
| /************************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 device *dev = &pdev->dev; |
| int ret, irq; |
| unsigned long clock_f; |
| struct cdns_wdt *wdt; |
| struct watchdog_device *cdns_wdt_device; |
| |
| wdt = devm_kzalloc(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; |
| |
| wdt->regs = devm_platform_ioremap_resource(pdev, 0); |
| if (IS_ERR(wdt->regs)) |
| return PTR_ERR(wdt->regs); |
| |
| /* Register the interrupt */ |
| wdt->rst = of_property_read_bool(dev->of_node, "reset-on-timeout"); |
| irq = platform_get_irq(pdev, 0); |
| if (!wdt->rst && irq >= 0) { |
| ret = devm_request_irq(dev, irq, cdns_wdt_irq_handler, 0, |
| pdev->name, pdev); |
| if (ret) { |
| dev_err(dev, |
| "cannot register interrupt handler err=%d\n", |
| ret); |
| return ret; |
| } |
| } |
| |
| /* Initialize the members of cdns_wdt structure */ |
| cdns_wdt_device->parent = dev; |
| |
| watchdog_init_timeout(cdns_wdt_device, wdt_timeout, dev); |
| watchdog_set_nowayout(cdns_wdt_device, nowayout); |
| watchdog_stop_on_reboot(cdns_wdt_device); |
| watchdog_set_drvdata(cdns_wdt_device, wdt); |
| |
| wdt->clk = devm_clk_get(dev, NULL); |
| if (IS_ERR(wdt->clk)) { |
| ret = PTR_ERR(wdt->clk); |
| if (ret != -EPROBE_DEFER) |
| dev_err(dev, "input clock not found\n"); |
| return ret; |
| } |
| |
| ret = clk_prepare_enable(wdt->clk); |
| if (ret) { |
| dev_err(dev, "unable to enable clock\n"); |
| return ret; |
| } |
| ret = devm_add_action_or_reset(dev, cdns_clk_disable_unprepare, |
| wdt->clk); |
| if (ret) |
| 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); |
| |
| watchdog_stop_on_reboot(cdns_wdt_device); |
| watchdog_stop_on_unregister(cdns_wdt_device); |
| ret = devm_watchdog_register_device(dev, cdns_wdt_device); |
| if (ret) |
| return ret; |
| platform_set_drvdata(pdev, wdt); |
| |
| dev_info(dev, "Xilinx Watchdog Timer with timeout %ds%s\n", |
| cdns_wdt_device->timeout, nowayout ? ", nowayout" : ""); |
| |
| return 0; |
| } |
| |
| /** |
| * 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 cdns_wdt *wdt = dev_get_drvdata(dev); |
| |
| if (watchdog_active(&wdt->cdns_wdt_device)) { |
| 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 cdns_wdt *wdt = dev_get_drvdata(dev); |
| |
| if (watchdog_active(&wdt->cdns_wdt_device)) { |
| 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 const 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, |
| .driver = { |
| .name = "cdns-wdt", |
| .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"); |