drivers/watchdog/intel-mid_wdt.c

   1 /*
   2  *      intel-mid_wdt: generic Intel MID SCU watchdog driver
   3  *
   4  *      Platforms supported so far:
   5  *      - Merrifield only
   6  *
   7  *      Copyright (C) 2014 Intel Corporation. All rights reserved.
   8  *      Contact: David Cohen <david.a.cohen@linux.intel.com>
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of version 2 of the GNU General
  12  *      Public License as published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/interrupt.h>
  16 #include <linux/module.h>
  17 #include <linux/nmi.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/watchdog.h>
  20 #include <linux/platform_data/intel-mid_wdt.h>
  21
  22 #include <asm/intel_scu_ipc.h>
  23 #include <asm/intel-mid.h>
  24
  25 #define IPC_WATCHDOG 0xf8
  26
  27 #define MID_WDT_PRETIMEOUT              15
  28 #define MID_WDT_TIMEOUT_MIN             (1 + MID_WDT_PRETIMEOUT)
  29 #define MID_WDT_TIMEOUT_MAX             170
  30 #define MID_WDT_DEFAULT_TIMEOUT         90
  31
  32 /* SCU watchdog messages */
  33 enum {
  34         SCU_WATCHDOG_START = 0,
  35         SCU_WATCHDOG_STOP,
  36         SCU_WATCHDOG_KEEPALIVE,
  37 };
  38
  39 static inline int wdt_command(int sub, u32 *in, int inlen)
  40 {
  41         return intel_scu_ipc_command(IPC_WATCHDOG, sub, in, inlen, NULL, 0);
  42 }
  43
  44 static int wdt_start(struct watchdog_device *wd)
  45 {
  46         struct device *dev = watchdog_get_drvdata(wd);
  47         int ret, in_size;
  48         int timeout = wd->timeout;
  49         struct ipc_wd_start {
  50                 u32 pretimeout;
  51                 u32 timeout;
  52         } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
  53
  54         /*
  55          * SCU expects the input size for watchdog IPC to
  56          * be based on 4 bytes
  57          */
  58         in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
  59
  60         ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size);
  61         if (ret)
  62                 dev_crit(dev, "error starting watchdog: %d\n", ret);
  63
  64         return ret;
  65 }
  66
  67 static int wdt_ping(struct watchdog_device *wd)
  68 {
  69         struct device *dev = watchdog_get_drvdata(wd);
  70         int ret;
  71
  72         ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0);
  73         if (ret)
  74                 dev_crit(dev, "Error executing keepalive: %d\n", ret);
  75
  76         return ret;
  77 }
  78
  79 static int wdt_stop(struct watchdog_device *wd)
  80 {
  81         struct device *dev = watchdog_get_drvdata(wd);
  82         int ret;
  83
  84         ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0);
  85         if (ret)
  86                 dev_crit(dev, "Error stopping watchdog: %d\n", ret);
  87
  88         return ret;
  89 }
  90
  91 static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
  92 {
  93         panic("Kernel Watchdog");
  94
  95         /* This code should not be reached */
  96         return IRQ_HANDLED;
  97 }
  98
  99 static const struct watchdog_info mid_wdt_info = {
 100         .identity = "Intel MID SCU watchdog",
 101         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 102 };
 103
 104 static const struct watchdog_ops mid_wdt_ops = {
 105         .owner = THIS_MODULE,
 106         .start = wdt_start,
 107         .stop = wdt_stop,
 108         .ping = wdt_ping,
 109 };
 110
 111 static int mid_wdt_probe(struct platform_device *pdev)
 112 {
 113         struct watchdog_device *wdt_dev;
 114         struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data;
 115         int ret;
 116
 117         if (!pdata) {
 118                 dev_err(&pdev->dev, "missing platform data\n");
 119                 return -EINVAL;
 120         }
 121
 122         if (pdata->probe) {
 123                 ret = pdata->probe(pdev);
 124                 if (ret)
 125                         return ret;
 126         }
 127
 128         wdt_dev = devm_kzalloc(&pdev->dev, sizeof(*wdt_dev), GFP_KERNEL);
 129         if (!wdt_dev)
 130                 return -ENOMEM;
 131
 132         wdt_dev->info = &mid_wdt_info;
 133         wdt_dev->ops = &mid_wdt_ops;
 134         wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
 135         wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
 136         wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
 137         wdt_dev->parent = &pdev->dev;
 138
 139         watchdog_set_drvdata(wdt_dev, &pdev->dev);
 140
 141         ret = devm_request_irq(&pdev->dev, pdata->irq, mid_wdt_irq,
 142                                IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
 143                                wdt_dev);
 144         if (ret) {
 145                 dev_err(&pdev->dev, "error requesting warning irq %d\n",
 146                         pdata->irq);
 147                 return ret;
 148         }
 149
 150         /*
 151          * The firmware followed by U-Boot leaves the watchdog running
 152          * with the default threshold which may vary. When we get here
 153          * we should make a decision to prevent any side effects before
 154          * user space daemon will take care of it. The best option,
 155          * taking into consideration that there is no way to read values
 156          * back from hardware, is to enforce watchdog being run with
 157          * deterministic values.
 158          */
 159         ret = wdt_start(wdt_dev);
 160         if (ret)
 161                 return ret;
 162
 163         /* Make sure the watchdog is serviced */
 164         set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
 165
 166         ret = devm_watchdog_register_device(&pdev->dev, wdt_dev);
 167         if (ret) {
 168                 dev_err(&pdev->dev, "error registering watchdog device\n");
 169                 return ret;
 170         }
 171
 172         dev_info(&pdev->dev, "Intel MID watchdog device probed\n");
 173
 174         return 0;
 175 }
 176
 177 static struct platform_driver mid_wdt_driver = {
 178         .probe          = mid_wdt_probe,
 179         .driver         = {
 180                 .name   = "intel_mid_wdt",
 181         },
 182 };
 183
 184 module_platform_driver(mid_wdt_driver);
 185
 186 MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
 187 MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
 188 MODULE_LICENSE("GPL");