drivers/watchdog/intel-mid_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *      intel-mid_wdt: generic Intel MID SCU watchdog driver
   4  *
   5  *      Platforms supported so far:
   6  *      - Merrifield only
   7  *
   8  *      Copyright (C) 2014 Intel Corporation. All rights reserved.
   9  *      Contact: David Cohen <david.a.cohen@linux.intel.com>
  10  */
  11
  12 #include <linux/bitops.h>
  13 #include <linux/device.h>
  14 #include <linux/errno.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/math.h>
  17 #include <linux/module.h>
  18 #include <linux/panic.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/types.h>
  21 #include <linux/watchdog.h>
  22
  23 #include <linux/platform_data/x86/intel-mid_wdt.h>
  24 #include <linux/platform_data/x86/intel_scu_ipc.h>
  25
  26 #define IPC_WATCHDOG 0xf8
  27
  28 #define MID_WDT_PRETIMEOUT              15
  29 #define MID_WDT_TIMEOUT_MIN             (1 + MID_WDT_PRETIMEOUT)
  30 #define MID_WDT_TIMEOUT_MAX             170
  31 #define MID_WDT_DEFAULT_TIMEOUT         90
  32
  33 /* SCU watchdog messages */
  34 enum {
  35         SCU_WATCHDOG_START = 0,
  36         SCU_WATCHDOG_STOP,
  37         SCU_WATCHDOG_KEEPALIVE,
  38 };
  39
  40 struct mid_wdt {
  41         struct watchdog_device wd;
  42         struct device *dev;
  43         struct intel_scu_ipc_dev *scu;
  44 };
  45
  46 static inline int
  47 wdt_command(struct mid_wdt *mid, int sub, const void *in, size_t inlen, size_t size)
  48 {
  49         struct intel_scu_ipc_dev *scu = mid->scu;
  50
  51         return intel_scu_ipc_dev_command_with_size(scu, IPC_WATCHDOG, sub, in,
  52                                                    inlen, size, NULL, 0);
  53 }
  54
  55 static int wdt_start(struct watchdog_device *wd)
  56 {
  57         struct mid_wdt *mid = watchdog_get_drvdata(wd);
  58         int ret, in_size;
  59         int timeout = wd->timeout;
  60         struct ipc_wd_start {
  61                 u32 pretimeout;
  62                 u32 timeout;
  63         } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
  64
  65         /*
  66          * SCU expects the input size for watchdog IPC to be 2 which is the
  67          * size of the structure in dwords. SCU IPC normally takes bytes
  68          * but this is a special case where we specify size to be different
  69          * than inlen.
  70          */
  71         in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
  72
  73         ret = wdt_command(mid, SCU_WATCHDOG_START, &ipc_wd_start,
  74                           sizeof(ipc_wd_start), in_size);
  75         if (ret)
  76                 dev_crit(mid->dev, "error starting watchdog: %d\n", ret);
  77
  78         return ret;
  79 }
  80
  81 static int wdt_ping(struct watchdog_device *wd)
  82 {
  83         struct mid_wdt *mid = watchdog_get_drvdata(wd);
  84         int ret;
  85
  86         ret = wdt_command(mid, SCU_WATCHDOG_KEEPALIVE, NULL, 0, 0);
  87         if (ret)
  88                 dev_crit(mid->dev, "Error executing keepalive: %d\n", ret);
  89
  90         return ret;
  91 }
  92
  93 static int wdt_stop(struct watchdog_device *wd)
  94 {
  95         struct mid_wdt *mid = watchdog_get_drvdata(wd);
  96         int ret;
  97
  98         ret = wdt_command(mid, SCU_WATCHDOG_STOP, NULL, 0, 0);
  99         if (ret)
 100                 dev_crit(mid->dev, "Error stopping watchdog: %d\n", ret);
 101
 102         return ret;
 103 }
 104
 105 static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
 106 {
 107         panic("Kernel Watchdog");
 108
 109         /* This code should not be reached */
 110         return IRQ_HANDLED;
 111 }
 112
 113 static const struct watchdog_info mid_wdt_info = {
 114         .identity = "Intel MID SCU watchdog",
 115         .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 116 };
 117
 118 static const struct watchdog_ops mid_wdt_ops = {
 119         .owner = THIS_MODULE,
 120         .start = wdt_start,
 121         .stop = wdt_stop,
 122         .ping = wdt_ping,
 123 };
 124
 125 static int mid_wdt_probe(struct platform_device *pdev)
 126 {
 127         struct device *dev = &pdev->dev;
 128         struct watchdog_device *wdt_dev;
 129         struct intel_mid_wdt_pdata *pdata = dev_get_platdata(dev);
 130         struct mid_wdt *mid;
 131         int ret;
 132
 133         if (!pdata) {
 134                 dev_err(dev, "missing platform data\n");
 135                 return -EINVAL;
 136         }
 137
 138         if (pdata->probe) {
 139                 ret = pdata->probe(pdev);
 140                 if (ret)
 141                         return ret;
 142         }
 143
 144         mid = devm_kzalloc(dev, sizeof(*mid), GFP_KERNEL);
 145         if (!mid)
 146                 return -ENOMEM;
 147
 148         mid->dev = dev;
 149         wdt_dev = &mid->wd;
 150
 151         wdt_dev->info = &mid_wdt_info;
 152         wdt_dev->ops = &mid_wdt_ops;
 153         wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
 154         wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
 155         wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
 156         wdt_dev->parent = dev;
 157
 158         watchdog_set_nowayout(wdt_dev, WATCHDOG_NOWAYOUT);
 159         watchdog_set_drvdata(wdt_dev, mid);
 160
 161         mid->scu = devm_intel_scu_ipc_dev_get(dev);
 162         if (!mid->scu)
 163                 return -EPROBE_DEFER;
 164
 165         ret = devm_request_irq(dev, pdata->irq, mid_wdt_irq,
 166                                IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
 167                                wdt_dev);
 168         if (ret) {
 169                 dev_err(dev, "error requesting warning irq %d\n", pdata->irq);
 170                 return ret;
 171         }
 172
 173         /*
 174          * The firmware followed by U-Boot leaves the watchdog running
 175          * with the default threshold which may vary. When we get here
 176          * we should make a decision to prevent any side effects before
 177          * user space daemon will take care of it. The best option,
 178          * taking into consideration that there is no way to read values
 179          * back from hardware, is to enforce watchdog being run with
 180          * deterministic values.
 181          */
 182         ret = wdt_start(wdt_dev);
 183         if (ret)
 184                 return ret;
 185
 186         /* Make sure the watchdog is serviced */
 187         set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
 188
 189         ret = devm_watchdog_register_device(dev, wdt_dev);
 190         if (ret)
 191                 return ret;
 192
 193         dev_info(dev, "Intel MID watchdog device probed\n");
 194
 195         return 0;
 196 }
 197
 198 static struct platform_driver mid_wdt_driver = {
 199         .probe          = mid_wdt_probe,
 200         .driver         = {
 201                 .name   = "intel_mid_wdt",
 202         },
 203 };
 204
 205 module_platform_driver(mid_wdt_driver);
 206
 207 MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
 208 MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
 209 MODULE_LICENSE("GPL");
 210 MODULE_ALIAS("platform:intel_mid_wdt");