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Release 4.10 drivers/watchdog/cadence_wdt.c

Directory: drivers/watchdog
/*
 * 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/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
 *
 * 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); }

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/*************************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; }

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/** * 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; }

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/** * 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; }

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/** * 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); }

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/** * 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; }

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/* * 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 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, }; /************************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_stop_on_reboot(cdns_wdt_device); 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); 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; }

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/** * 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); clk_disable_unprepare(wdt->clk); return 0; }

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/** * 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); }

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/** * 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 = to_platform_device(dev); struct cdns_wdt *wdt = platform_get_drvdata(pdev); if (watchdog_active(&wdt->cdns_wdt_device)) { cdns_wdt_stop(&wdt->cdns_wdt_device); clk_disable_unprepare(wdt->clk); } return 0; }

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/** * 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 = to_platform_device(dev); struct cdns_wdt *wdt = platform_get_drvdata(pdev); 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; }

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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", .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");

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Directory: drivers/watchdog
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