drivers/watchdog/gemini_wdt.c

   1 /*
   2  * Watchdog driver for Cortina Systems Gemini SoC
   3  *
   4  * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
   5  *
   6  * Inspired by the out-of-tree drivers from OpenWRT:
   7  * Copyright (C) 2009 Paulius Zaleckas <paulius.zaleckas@teltonika.lt>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/bitops.h>
  15 #include <linux/init.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/io.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/of_device.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/slab.h>
  23 #include <linux/watchdog.h>
  24
  25 #define GEMINI_WDCOUNTER        0x0
  26 #define GEMINI_WDLOAD           0x4
  27 #define GEMINI_WDRESTART        0x8
  28 #define GEMINI_WDCR             0xC
  29
  30 #define WDRESTART_MAGIC         0x5AB9
  31
  32 #define WDCR_CLOCK_5MHZ         BIT(4)
  33 #define WDCR_SYS_RST            BIT(1)
  34 #define WDCR_ENABLE             BIT(0)
  35
  36 #define WDT_CLOCK               5000000         /* 5 MHz */
  37
  38 struct gemini_wdt {
  39         struct watchdog_device  wdd;
  40         struct device           *dev;
  41         void __iomem            *base;
  42 };
  43
  44 static inline
  45 struct gemini_wdt *to_gemini_wdt(struct watchdog_device *wdd)
  46 {
  47         return container_of(wdd, struct gemini_wdt, wdd);
  48 }
  49
  50 static int gemini_wdt_start(struct watchdog_device *wdd)
  51 {
  52         struct gemini_wdt *gwdt = to_gemini_wdt(wdd);
  53
  54         writel(wdd->timeout * WDT_CLOCK, gwdt->base + GEMINI_WDLOAD);
  55         writel(WDRESTART_MAGIC, gwdt->base + GEMINI_WDRESTART);
  56         /* set clock before enabling */
  57         writel(WDCR_CLOCK_5MHZ | WDCR_SYS_RST,
  58                         gwdt->base + GEMINI_WDCR);
  59         writel(WDCR_CLOCK_5MHZ | WDCR_SYS_RST | WDCR_ENABLE,
  60                         gwdt->base + GEMINI_WDCR);
  61
  62         return 0;
  63 }
  64
  65 static int gemini_wdt_stop(struct watchdog_device *wdd)
  66 {
  67         struct gemini_wdt *gwdt = to_gemini_wdt(wdd);
  68
  69         writel(0, gwdt->base + GEMINI_WDCR);
  70
  71         return 0;
  72 }
  73
  74 static int gemini_wdt_ping(struct watchdog_device *wdd)
  75 {
  76         struct gemini_wdt *gwdt = to_gemini_wdt(wdd);
  77
  78         writel(WDRESTART_MAGIC, gwdt->base + GEMINI_WDRESTART);
  79
  80         return 0;
  81 }
  82
  83 static int gemini_wdt_set_timeout(struct watchdog_device *wdd,
  84                                   unsigned int timeout)
  85 {
  86         wdd->timeout = timeout;
  87         if (watchdog_active(wdd))
  88                 gemini_wdt_start(wdd);
  89
  90         return 0;
  91 }
  92
  93 static irqreturn_t gemini_wdt_interrupt(int irq, void *data)
  94 {
  95         struct gemini_wdt *gwdt = data;
  96
  97         watchdog_notify_pretimeout(&gwdt->wdd);
  98
  99         return IRQ_HANDLED;
 100 }
 101
 102 static const struct watchdog_ops gemini_wdt_ops = {
 103         .start          = gemini_wdt_start,
 104         .stop           = gemini_wdt_stop,
 105         .ping           = gemini_wdt_ping,
 106         .set_timeout    = gemini_wdt_set_timeout,
 107         .owner          = THIS_MODULE,
 108 };
 109
 110 static const struct watchdog_info gemini_wdt_info = {
 111         .options        = WDIOF_KEEPALIVEPING
 112                         | WDIOF_MAGICCLOSE
 113                         | WDIOF_SETTIMEOUT,
 114         .identity       = KBUILD_MODNAME,
 115 };
 116
 117
 118 static int gemini_wdt_probe(struct platform_device *pdev)
 119 {
 120         struct device *dev = &pdev->dev;
 121         struct resource *res;
 122         struct gemini_wdt *gwdt;
 123         unsigned int reg;
 124         int irq;
 125         int ret;
 126
 127         gwdt = devm_kzalloc(dev, sizeof(*gwdt), GFP_KERNEL);
 128         if (!gwdt)
 129                 return -ENOMEM;
 130
 131         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 132         gwdt->base = devm_ioremap_resource(dev, res);
 133         if (IS_ERR(gwdt->base))
 134                 return PTR_ERR(gwdt->base);
 135
 136         irq = platform_get_irq(pdev, 0);
 137         if (!irq)
 138                 return -EINVAL;
 139
 140         gwdt->dev = dev;
 141         gwdt->wdd.info = &gemini_wdt_info;
 142         gwdt->wdd.ops = &gemini_wdt_ops;
 143         gwdt->wdd.min_timeout = 1;
 144         gwdt->wdd.max_timeout = 0xFFFFFFFF / WDT_CLOCK;
 145         gwdt->wdd.parent = dev;
 146
 147         /*
 148          * If 'timeout-sec' unspecified in devicetree, assume a 13 second
 149          * default.
 150          */
 151         gwdt->wdd.timeout = 13U;
 152         watchdog_init_timeout(&gwdt->wdd, 0, dev);
 153
 154         reg = readw(gwdt->base + GEMINI_WDCR);
 155         if (reg & WDCR_ENABLE) {
 156                 /* Watchdog was enabled by the bootloader, disable it. */
 157                 reg &= ~WDCR_ENABLE;
 158                 writel(reg, gwdt->base + GEMINI_WDCR);
 159         }
 160
 161         ret = devm_request_irq(dev, irq, gemini_wdt_interrupt, 0,
 162                                "watchdog bark", gwdt);
 163         if (ret)
 164                 return ret;
 165
 166         ret = devm_watchdog_register_device(dev, &gwdt->wdd);
 167         if (ret) {
 168                 dev_err(&pdev->dev, "failed to register watchdog\n");
 169                 return ret;
 170         }
 171
 172         /* Set up platform driver data */
 173         platform_set_drvdata(pdev, gwdt);
 174         dev_info(dev, "Gemini watchdog driver enabled\n");
 175
 176         return 0;
 177 }
 178
 179 static int __maybe_unused gemini_wdt_suspend(struct device *dev)
 180 {
 181         struct gemini_wdt *gwdt = dev_get_drvdata(dev);
 182         unsigned int reg;
 183
 184         reg = readw(gwdt->base + GEMINI_WDCR);
 185         reg &= ~WDCR_ENABLE;
 186         writel(reg, gwdt->base + GEMINI_WDCR);
 187
 188         return 0;
 189 }
 190
 191 static int __maybe_unused gemini_wdt_resume(struct device *dev)
 192 {
 193         struct gemini_wdt *gwdt = dev_get_drvdata(dev);
 194         unsigned int reg;
 195
 196         if (watchdog_active(&gwdt->wdd)) {
 197                 reg = readw(gwdt->base + GEMINI_WDCR);
 198                 reg |= WDCR_ENABLE;
 199                 writel(reg, gwdt->base + GEMINI_WDCR);
 200         }
 201
 202         return 0;
 203 }
 204
 205 static const struct dev_pm_ops gemini_wdt_dev_pm_ops = {
 206         SET_SYSTEM_SLEEP_PM_OPS(gemini_wdt_suspend,
 207                                 gemini_wdt_resume)
 208 };
 209
 210 #ifdef CONFIG_OF
 211 static const struct of_device_id gemini_wdt_match[] = {
 212         { .compatible = "cortina,gemini-watchdog" },
 213         {},
 214 };
 215 MODULE_DEVICE_TABLE(of, gemini_wdt_match);
 216 #endif
 217
 218 static struct platform_driver gemini_wdt_driver = {
 219         .probe          = gemini_wdt_probe,
 220         .driver         = {
 221                 .name   = "gemini-wdt",
 222                 .of_match_table = of_match_ptr(gemini_wdt_match),
 223                 .pm = &gemini_wdt_dev_pm_ops,
 224         },
 225 };
 226 module_platform_driver(gemini_wdt_driver);
 227 MODULE_AUTHOR("Linus Walleij");
 228 MODULE_DESCRIPTION("Watchdog driver for Gemini");
 229 MODULE_LICENSE("GPL");