drivers/watchdog/ixp4xx_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * drivers/char/watchdog/ixp4xx_wdt.c
   4  *
   5  * Watchdog driver for Intel IXP4xx network processors
   6  *
   7  * Author: Deepak Saxena <dsaxena@plexity.net>
   8  * Author: Linus Walleij <linus.walleij@linaro.org>
   9  *
  10  * Copyright 2004 (c) MontaVista, Software, Inc.
  11  * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/types.h>
  16 #include <linux/kernel.h>
  17 #include <linux/watchdog.h>
  18 #include <linux/bits.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/clk.h>
  21 #include <linux/soc/ixp4xx/cpu.h>
  22
  23 struct ixp4xx_wdt {
  24         struct watchdog_device wdd;
  25         void __iomem *base;
  26         unsigned long rate;
  27 };
  28
  29 /* Fallback if we do not have a clock for this */
  30 #define IXP4XX_TIMER_FREQ       66666000
  31
  32 /* Registers after the timer registers */
  33 #define IXP4XX_OSWT_OFFSET      0x14  /* Watchdog Timer */
  34 #define IXP4XX_OSWE_OFFSET      0x18  /* Watchdog Enable */
  35 #define IXP4XX_OSWK_OFFSET      0x1C  /* Watchdog Key */
  36 #define IXP4XX_OSST_OFFSET      0x20  /* Timer Status */
  37
  38 #define IXP4XX_OSST_TIMER_WDOG_PEND     0x00000008
  39 #define IXP4XX_OSST_TIMER_WARM_RESET    0x00000010
  40 #define IXP4XX_WDT_KEY                  0x0000482E
  41 #define IXP4XX_WDT_RESET_ENABLE         0x00000001
  42 #define IXP4XX_WDT_IRQ_ENABLE           0x00000002
  43 #define IXP4XX_WDT_COUNT_ENABLE         0x00000004
  44
  45 static inline
  46 struct ixp4xx_wdt *to_ixp4xx_wdt(struct watchdog_device *wdd)
  47 {
  48         return container_of(wdd, struct ixp4xx_wdt, wdd);
  49 }
  50
  51 static int ixp4xx_wdt_start(struct watchdog_device *wdd)
  52 {
  53         struct ixp4xx_wdt *iwdt = to_ixp4xx_wdt(wdd);
  54
  55         __raw_writel(IXP4XX_WDT_KEY, iwdt->base + IXP4XX_OSWK_OFFSET);
  56         __raw_writel(0, iwdt->base + IXP4XX_OSWE_OFFSET);
  57         __raw_writel(wdd->timeout * iwdt->rate,
  58                      iwdt->base + IXP4XX_OSWT_OFFSET);
  59         __raw_writel(IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE,
  60                      iwdt->base + IXP4XX_OSWE_OFFSET);
  61         __raw_writel(0, iwdt->base + IXP4XX_OSWK_OFFSET);
  62
  63         return 0;
  64 }
  65
  66 static int ixp4xx_wdt_stop(struct watchdog_device *wdd)
  67 {
  68         struct ixp4xx_wdt *iwdt = to_ixp4xx_wdt(wdd);
  69
  70         __raw_writel(IXP4XX_WDT_KEY, iwdt->base + IXP4XX_OSWK_OFFSET);
  71         __raw_writel(0, iwdt->base + IXP4XX_OSWE_OFFSET);
  72         __raw_writel(0, iwdt->base + IXP4XX_OSWK_OFFSET);
  73
  74         return 0;
  75 }
  76
  77 static int ixp4xx_wdt_set_timeout(struct watchdog_device *wdd,
  78                                   unsigned int timeout)
  79 {
  80         wdd->timeout = timeout;
  81         if (watchdog_active(wdd))
  82                 ixp4xx_wdt_start(wdd);
  83
  84         return 0;
  85 }
  86
  87 static int ixp4xx_wdt_restart(struct watchdog_device *wdd,
  88                               unsigned long action, void *data)
  89 {
  90         struct ixp4xx_wdt *iwdt = to_ixp4xx_wdt(wdd);
  91
  92         __raw_writel(IXP4XX_WDT_KEY, iwdt->base + IXP4XX_OSWK_OFFSET);
  93         __raw_writel(0, iwdt->base + IXP4XX_OSWT_OFFSET);
  94         __raw_writel(IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE,
  95                      iwdt->base + IXP4XX_OSWE_OFFSET);
  96
  97         return 0;
  98 }
  99
 100 static const struct watchdog_ops ixp4xx_wdt_ops = {
 101         .start = ixp4xx_wdt_start,
 102         .stop = ixp4xx_wdt_stop,
 103         .set_timeout = ixp4xx_wdt_set_timeout,
 104         .restart = ixp4xx_wdt_restart,
 105         .owner = THIS_MODULE,
 106 };
 107
 108 /*
 109  * The A0 version of the IXP422 had a bug in the watchdog making
 110  * is useless, but we still need to use it to restart the system
 111  * as it is the only way, so in this special case we register a
 112  * "dummy" watchdog that doesn't really work, but will support
 113  * the restart operation.
 114  */
 115 static int ixp4xx_wdt_dummy(struct watchdog_device *wdd)
 116 {
 117         return 0;
 118 }
 119
 120 static const struct watchdog_ops ixp4xx_wdt_restart_only_ops = {
 121         .start = ixp4xx_wdt_dummy,
 122         .stop = ixp4xx_wdt_dummy,
 123         .restart = ixp4xx_wdt_restart,
 124         .owner = THIS_MODULE,
 125 };
 126
 127 static const struct watchdog_info ixp4xx_wdt_info = {
 128         .options = WDIOF_KEEPALIVEPING
 129                 | WDIOF_MAGICCLOSE
 130                 | WDIOF_SETTIMEOUT,
 131         .identity = KBUILD_MODNAME,
 132 };
 133
 134 static int ixp4xx_wdt_probe(struct platform_device *pdev)
 135 {
 136         static const struct watchdog_ops *iwdt_ops;
 137         struct device *dev = &pdev->dev;
 138         struct ixp4xx_wdt *iwdt;
 139         struct clk *clk;
 140         int ret;
 141
 142         if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
 143                 dev_info(dev, "Rev. A0 IXP42x CPU detected - only restart supported\n");
 144                 iwdt_ops = &ixp4xx_wdt_restart_only_ops;
 145         } else {
 146                 iwdt_ops = &ixp4xx_wdt_ops;
 147         }
 148
 149         iwdt = devm_kzalloc(dev, sizeof(*iwdt), GFP_KERNEL);
 150         if (!iwdt)
 151                 return -ENOMEM;
 152         iwdt->base = (void __iomem *)dev->platform_data;
 153
 154         /*
 155          * Retrieve rate from a fixed clock from the device tree if
 156          * the parent has that, else use the default clock rate.
 157          */
 158         clk = devm_clk_get_enabled(dev->parent, NULL);
 159         if (!IS_ERR(clk))
 160                 iwdt->rate = clk_get_rate(clk);
 161
 162         if (!iwdt->rate)
 163                 iwdt->rate = IXP4XX_TIMER_FREQ;
 164
 165         iwdt->wdd.info = &ixp4xx_wdt_info;
 166         iwdt->wdd.ops = iwdt_ops;
 167         iwdt->wdd.min_timeout = 1;
 168         iwdt->wdd.max_timeout = U32_MAX / iwdt->rate;
 169         iwdt->wdd.parent = dev;
 170         /* Default to 60 seconds */
 171         iwdt->wdd.timeout = 60U;
 172         watchdog_init_timeout(&iwdt->wdd, 0, dev);
 173
 174         if (__raw_readl(iwdt->base + IXP4XX_OSST_OFFSET) &
 175             IXP4XX_OSST_TIMER_WARM_RESET)
 176                 iwdt->wdd.bootstatus = WDIOF_CARDRESET;
 177
 178         ret = devm_watchdog_register_device(dev, &iwdt->wdd);
 179         if (ret)
 180                 return ret;
 181
 182         dev_info(dev, "IXP4xx watchdog available\n");
 183
 184         return 0;
 185 }
 186
 187 static struct platform_driver ixp4xx_wdt_driver = {
 188         .probe = ixp4xx_wdt_probe,
 189         .driver = {
 190                 .name   = "ixp4xx-watchdog",
 191         },
 192 };
 193 module_platform_driver(ixp4xx_wdt_driver);
 194
 195 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 196 MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
 197 MODULE_LICENSE("GPL");