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 int bcm7038_wdt_probe(struct platform_device *pdev)
 111 {
 112         struct device *dev = &pdev->dev;
 113         struct bcm7038_watchdog *wdt;
 114         struct resource *res;
 115         int err;
 116
 117         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 118         if (!wdt)
 119                 return -ENOMEM;
 120
 121         platform_set_drvdata(pdev, wdt);
 122
 123         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 124         wdt->base = devm_ioremap_resource(dev, res);
 125         if (IS_ERR(wdt->base))
 126                 return PTR_ERR(wdt->base);
 127
 128         wdt->clk = devm_clk_get(dev, NULL);
 129         /* If unable to get clock, use default frequency */
 130         if (!IS_ERR(wdt->clk)) {
 131                 err = clk_prepare_enable(wdt->clk);
 132                 if (err)
 133                         return err;
 134                 wdt->rate = clk_get_rate(wdt->clk);
 135                 /* Prevent divide-by-zero exception */
 136                 if (!wdt->rate)
 137                         wdt->rate = WDT_DEFAULT_RATE;
 138         } else {
 139                 wdt->rate = WDT_DEFAULT_RATE;
 140                 wdt->clk = NULL;
 141         }
 142
 143         wdt->wdd.info           = &bcm7038_wdt_info;
 144         wdt->wdd.ops            = &bcm7038_wdt_ops;
 145         wdt->wdd.min_timeout    = WDT_MIN_TIMEOUT;
 146         wdt->wdd.timeout        = WDT_DEFAULT_TIMEOUT;
 147         wdt->wdd.max_timeout    = 0xffffffff / wdt->rate;
 148         wdt->wdd.parent         = dev;
 149         watchdog_set_drvdata(&wdt->wdd, wdt);
 150
 151         err = watchdog_register_device(&wdt->wdd);
 152         if (err) {
 153                 dev_err(dev, "Failed to register watchdog device\n");
 154                 clk_disable_unprepare(wdt->clk);
 155                 return err;
 156         }
 157
 158         dev_info(dev, "Registered BCM7038 Watchdog\n");
 159
 160         return 0;
 161 }
 162
 163 static int bcm7038_wdt_remove(struct platform_device *pdev)
 164 {
 165         struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
 166
 167         if (!nowayout)
 168                 bcm7038_wdt_stop(&wdt->wdd);
 169
 170         watchdog_unregister_device(&wdt->wdd);
 171         clk_disable_unprepare(wdt->clk);
 172
 173         return 0;
 174 }
 175
 176 #ifdef CONFIG_PM_SLEEP
 177 static int bcm7038_wdt_suspend(struct device *dev)
 178 {
 179         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 180
 181         if (watchdog_active(&wdt->wdd))
 182                 return bcm7038_wdt_stop(&wdt->wdd);
 183
 184         return 0;
 185 }
 186
 187 static int bcm7038_wdt_resume(struct device *dev)
 188 {
 189         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 190
 191         if (watchdog_active(&wdt->wdd))
 192                 return bcm7038_wdt_start(&wdt->wdd);
 193
 194         return 0;
 195 }
 196 #endif
 197
 198 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
 199                          bcm7038_wdt_resume);
 200
 201 static void bcm7038_wdt_shutdown(struct platform_device *pdev)
 202 {
 203         struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev);
 204
 205         if (watchdog_active(&wdt->wdd))
 206                 bcm7038_wdt_stop(&wdt->wdd);
 207 }
 208
 209 static const struct of_device_id bcm7038_wdt_match[] = {
 210         { .compatible = "brcm,bcm7038-wdt" },
 211         {},
 212 };
 213 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
 214
 215 static struct platform_driver bcm7038_wdt_driver = {
 216         .probe          = bcm7038_wdt_probe,
 217         .remove         = bcm7038_wdt_remove,
 218         .shutdown       = bcm7038_wdt_shutdown,
 219         .driver         = {
 220                 .name           = "bcm7038-wdt",
 221                 .of_match_table = bcm7038_wdt_match,
 222                 .pm             = &bcm7038_wdt_pm_ops,
 223         }
 224 };
 225 module_platform_driver(bcm7038_wdt_driver);
 226
 227 module_param(nowayout, bool, 0);
 228 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 229         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 230 MODULE_LICENSE("GPL");
 231 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
 232 MODULE_AUTHOR("Justin Chen");