LXR linux/drivers/watchdog/intel-mid

   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 */
  30enum {
  31        SCU_WATCHDOG_START = 0,
  32        SCU_WATCHDOG_STOP,
  33        SCU_WATCHDOG_KEEPALIVE,
  34};
  35
  36static 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
  41static 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
  64static 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
  76static 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
  88static 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
  96static const struct watchdog_info mid_wdt_info = {
  97        .identity = "Intel MID SCU watchdog",
  98        .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
  99};
 100
 101static 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
 108static 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_drvdata(wdt_dev, dev);
 138
 139        ret = devm_request_irq(dev, pdata->irq, mid_wdt_irq,
 140                               IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
 141                               wdt_dev);
 142        if (ret) {
 143                dev_err(dev, "error requesting warning irq %d\n", pdata->irq);
 144                return ret;
 145        }
 146
 147        /*
 148         * The firmware followed by U-Boot leaves the watchdog running
 149         * with the default threshold which may vary. When we get here
 150         * we should make a decision to prevent any side effects before
 151         * user space daemon will take care of it. The best option,
 152         * taking into consideration that there is no way to read values
 153         * back from hardware, is to enforce watchdog being run with
 154         * deterministic values.
 155         */
 156        ret = wdt_start(wdt_dev);
 157        if (ret)
 158                return ret;
 159
 160        /* Make sure the watchdog is serviced */
 161        set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
 162
 163        ret = devm_watchdog_register_device(dev, wdt_dev);
 164        if (ret)
 165                return ret;
 166
 167        dev_info(dev, "Intel MID watchdog device probed\n");
 168
 169        return 0;
 170}
 171
 172static struct platform_driver mid_wdt_driver = {
 173        .probe          = mid_wdt_probe,
 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