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