LXR linux/drivers/watchdog/intel-mid

   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 */
  33enum {
  34        SCU_WATCHDOG_START = 0,
  35        SCU_WATCHDOG_STOP,
  36        SCU_WATCHDOG_KEEPALIVE,
  37};
  38
  39static 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
  44static 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
  67static 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
  79static 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
  91static 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
  99static const struct watchdog_info mid_wdt_info = {
 100        .identity = "Intel MID SCU watchdog",
 101        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 102};
 103
 104static 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
 111static 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
 177static struct platform_driver mid_wdt_driver = {
 178        .probe          = mid_wdt_probe,
 179        .driver         = {
 180                .name   = "intel_mid_wdt",
 181        },
 182};
 183
 184module_platform_driver(mid_wdt_driver);
 185
 186MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
 187MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
 188MODULE_LICENSE("GPL");
 189