drivers/watchdog/bcm7038_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2015 Broadcom Corporation
   4  *
   5  */
   6
   7 #include <linux/clk.h>
   8 #include <linux/init.h>
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/pm.h>
  14 #include <linux/watchdog.h>
  15
  16 #define WDT_START_1             0xff00
  17 #define WDT_START_2             0x00ff
  18 #define WDT_STOP_1              0xee00
  19 #define WDT_STOP_2              0x00ee
  20
  21 #define WDT_TIMEOUT_REG         0x0
  22 #define WDT_CMD_REG             0x4
  23
  24 #define WDT_MIN_TIMEOUT         1 /* seconds */
  25 #define WDT_DEFAULT_TIMEOUT     30 /* seconds */
  26 #define WDT_DEFAULT_RATE        27000000
  27
  28 struct bcm7038_watchdog {
  29         void __iomem            *base;
  30         struct watchdog_device  wdd;
  31         u32                     rate;
  32         struct clk              *clk;
  33 };
  34
  35 static bool nowayout = WATCHDOG_NOWAYOUT;
  36
  37 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
  38 {
  39         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
  40         u32 timeout;
  41
  42         timeout = wdt->rate * wdog->timeout;
  43
  44         writel(timeout, wdt->base + WDT_TIMEOUT_REG);
  45 }
  46
  47 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
  48 {
  49         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
  50
  51         writel(WDT_START_1, wdt->base + WDT_CMD_REG);
  52         writel(WDT_START_2, wdt->base + WDT_CMD_REG);
  53
  54         return 0;
  55 }
  56
  57 static int bcm7038_wdt_start(struct watchdog_device *wdog)
  58 {
  59         bcm7038_wdt_set_timeout_reg(wdog);
  60         bcm7038_wdt_ping(wdog);
  61
  62         return 0;
  63 }
  64
  65 static int bcm7038_wdt_stop(struct watchdog_device *wdog)
  66 {
  67         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
  68
  69         writel(WDT_STOP_1, wdt->base + WDT_CMD_REG);
  70         writel(WDT_STOP_2, wdt->base + WDT_CMD_REG);
  71
  72         return 0;
  73 }
  74
  75 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
  76                                    unsigned int t)
  77 {
  78         /* Can't modify timeout value if watchdog timer is running */
  79         bcm7038_wdt_stop(wdog);
  80         wdog->timeout = t;
  81         bcm7038_wdt_start(wdog);
  82
  83         return 0;
  84 }
  85
  86 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
  87 {
  88         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
  89         u32 time_left;
  90
  91         time_left = readl(wdt->base + WDT_CMD_REG);
  92
  93         return time_left / wdt->rate;
  94 }
  95
  96 static const struct watchdog_info bcm7038_wdt_info = {
  97         .identity       = "Broadcom BCM7038 Watchdog Timer",
  98         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
  99                                 WDIOF_MAGICCLOSE
 100 };
 101
 102 static const struct watchdog_ops bcm7038_wdt_ops = {
 103         .owner          = THIS_MODULE,
 104         .start          = bcm7038_wdt_start,
 105         .stop           = bcm7038_wdt_stop,
 106         .set_timeout    = bcm7038_wdt_set_timeout,
 107         .get_timeleft   = bcm7038_wdt_get_timeleft,
 108 };
 109
 110 static void bcm7038_clk_disable_unprepare(void *data)
 111 {
 112         clk_disable_unprepare(data);
 113 }
 114
 115 static int bcm7038_wdt_probe(struct platform_device *pdev)
 116 {
 117         struct device *dev = &pdev->dev;
 118         struct bcm7038_watchdog *wdt;
 119         int err;
 120
 121         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 122         if (!wdt)
 123                 return -ENOMEM;
 124
 125         platform_set_drvdata(pdev, wdt);
 126
 127         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 128         if (IS_ERR(wdt->base))
 129                 return PTR_ERR(wdt->base);
 130
 131         wdt->clk = devm_clk_get(dev, NULL);
 132         /* If unable to get clock, use default frequency */
 133         if (!IS_ERR(wdt->clk)) {
 134                 err = clk_prepare_enable(wdt->clk);
 135                 if (err)
 136                         return err;
 137                 err = devm_add_action_or_reset(dev,
 138                                                bcm7038_clk_disable_unprepare,
 139                                                wdt->clk);
 140                 if (err)
 141                         return err;
 142                 wdt->rate = clk_get_rate(wdt->clk);
 143                 /* Prevent divide-by-zero exception */
 144                 if (!wdt->rate)
 145                         wdt->rate = WDT_DEFAULT_RATE;
 146         } else {
 147                 wdt->rate = WDT_DEFAULT_RATE;
 148                 wdt->clk = NULL;
 149         }
 150
 151         wdt->wdd.info           = &bcm7038_wdt_info;
 152         wdt->wdd.ops            = &bcm7038_wdt_ops;
 153         wdt->wdd.min_timeout    = WDT_MIN_TIMEOUT;
 154         wdt->wdd.timeout        = WDT_DEFAULT_TIMEOUT;
 155         wdt->wdd.max_timeout    = 0xffffffff / wdt->rate;
 156         wdt->wdd.parent         = dev;
 157         watchdog_set_drvdata(&wdt->wdd, wdt);
 158
 159         watchdog_stop_on_reboot(&wdt->wdd);
 160         watchdog_stop_on_unregister(&wdt->wdd);
 161         err = devm_watchdog_register_device(dev, &wdt->wdd);
 162         if (err)
 163                 return err;
 164
 165         dev_info(dev, "Registered BCM7038 Watchdog\n");
 166
 167         return 0;
 168 }
 169
 170 #ifdef CONFIG_PM_SLEEP
 171 static int bcm7038_wdt_suspend(struct device *dev)
 172 {
 173         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 174
 175         if (watchdog_active(&wdt->wdd))
 176                 return bcm7038_wdt_stop(&wdt->wdd);
 177
 178         return 0;
 179 }
 180
 181 static int bcm7038_wdt_resume(struct device *dev)
 182 {
 183         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 184
 185         if (watchdog_active(&wdt->wdd))
 186                 return bcm7038_wdt_start(&wdt->wdd);
 187
 188         return 0;
 189 }
 190 #endif
 191
 192 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
 193                          bcm7038_wdt_resume);
 194
 195 static const struct of_device_id bcm7038_wdt_match[] = {
 196         { .compatible = "brcm,bcm7038-wdt" },
 197         {},
 198 };
 199 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
 200
 201 static struct platform_driver bcm7038_wdt_driver = {
 202         .probe          = bcm7038_wdt_probe,
 203         .driver         = {
 204                 .name           = "bcm7038-wdt",
 205                 .of_match_table = bcm7038_wdt_match,
 206                 .pm             = &bcm7038_wdt_pm_ops,
 207         }
 208 };
 209 module_platform_driver(bcm7038_wdt_driver);
 210
 211 module_param(nowayout, bool, 0);
 212 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 213         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 214 MODULE_LICENSE("GPL");
 215 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
 216 MODULE_AUTHOR("Justin Chen");