linux/drivers/watchdog/intel-mid_wdt.c
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   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        int ret, in_size;
  47        int timeout = wd->timeout;
  48        struct ipc_wd_start {
  49                u32 pretimeout;
  50                u32 timeout;
  51        } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
  52
  53        /*
  54         * SCU expects the input size for watchdog IPC to
  55         * be based on 4 bytes
  56         */
  57        in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
  58
  59        ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size);
  60        if (ret) {
  61                struct device *dev = watchdog_get_drvdata(wd);
  62                dev_crit(dev, "error starting watchdog: %d\n", ret);
  63        }
  64
  65        return ret;
  66}
  67
  68static int wdt_ping(struct watchdog_device *wd)
  69{
  70        int ret;
  71
  72        ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0);
  73        if (ret) {
  74                struct device *dev = watchdog_get_drvdata(wd);
  75                dev_crit(dev, "Error executing keepalive: 0x%x\n", ret);
  76        }
  77
  78        return ret;
  79}
  80
  81static int wdt_stop(struct watchdog_device *wd)
  82{
  83        int ret;
  84
  85        ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0);
  86        if (ret) {
  87                struct device *dev = watchdog_get_drvdata(wd);
  88                dev_crit(dev, "Error stopping watchdog: 0x%x\n", ret);
  89        }
  90
  91        return ret;
  92}
  93
  94static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
  95{
  96        panic("Kernel Watchdog");
  97
  98        /* This code should not be reached */
  99        return IRQ_HANDLED;
 100}
 101
 102static const struct watchdog_info mid_wdt_info = {
 103        .identity = "Intel MID SCU watchdog",
 104        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
 105};
 106
 107static const struct watchdog_ops mid_wdt_ops = {
 108        .owner = THIS_MODULE,
 109        .start = wdt_start,
 110        .stop = wdt_stop,
 111        .ping = wdt_ping,
 112};
 113
 114static int mid_wdt_probe(struct platform_device *pdev)
 115{
 116        struct watchdog_device *wdt_dev;
 117        struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data;
 118        int ret;
 119
 120        if (!pdata) {
 121                dev_err(&pdev->dev, "missing platform data\n");
 122                return -EINVAL;
 123        }
 124
 125        if (pdata->probe) {
 126                ret = pdata->probe(pdev);
 127                if (ret)
 128                        return ret;
 129        }
 130
 131        wdt_dev = devm_kzalloc(&pdev->dev, sizeof(*wdt_dev), GFP_KERNEL);
 132        if (!wdt_dev)
 133                return -ENOMEM;
 134
 135        wdt_dev->info = &mid_wdt_info;
 136        wdt_dev->ops = &mid_wdt_ops;
 137        wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
 138        wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
 139        wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
 140
 141        watchdog_set_drvdata(wdt_dev, &pdev->dev);
 142        platform_set_drvdata(pdev, wdt_dev);
 143
 144        ret = devm_request_irq(&pdev->dev, pdata->irq, mid_wdt_irq,
 145                               IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
 146                               wdt_dev);
 147        if (ret) {
 148                dev_err(&pdev->dev, "error requesting warning irq %d\n",
 149                        pdata->irq);
 150                return ret;
 151        }
 152
 153        ret = watchdog_register_device(wdt_dev);
 154        if (ret) {
 155                dev_err(&pdev->dev, "error registering watchdog device\n");
 156                return ret;
 157        }
 158
 159        dev_info(&pdev->dev, "Intel MID watchdog device probed\n");
 160
 161        return 0;
 162}
 163
 164static int mid_wdt_remove(struct platform_device *pdev)
 165{
 166        struct watchdog_device *wd = platform_get_drvdata(pdev);
 167        watchdog_unregister_device(wd);
 168        return 0;
 169}
 170
 171static struct platform_driver mid_wdt_driver = {
 172        .probe          = mid_wdt_probe,
 173        .remove         = mid_wdt_remove,
 174        .driver         = {
 175                .name   = "intel_mid_wdt",
 176        },
 177};
 178
 179module_platform_driver(mid_wdt_driver);
 180
 181MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
 182MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
 183MODULE_LICENSE("GPL");
 184
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