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/*
* intel-mid_wdt: generic Intel MID SCU watchdog driver
*
* Platforms supported so far:
* - Merrifield only
*
* Copyright (C) 2014 Intel Corporation. All rights reserved.
* Contact: David Cohen <david.a.cohen@linux.intel.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General
* Public License as published by the Free Software Foundation.
*/
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/nmi.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/platform_data/intel-mid_wdt.h>
#include <asm/intel_scu_ipc.h>
#include <asm/intel-mid.h>
#define IPC_WATCHDOG 0xf8
#define MID_WDT_PRETIMEOUT 15
#define MID_WDT_TIMEOUT_MIN (1 + MID_WDT_PRETIMEOUT)
#define MID_WDT_TIMEOUT_MAX 170
#define MID_WDT_DEFAULT_TIMEOUT 90
/* SCU watchdog messages */
enum {
SCU_WATCHDOG_START = 0,
SCU_WATCHDOG_STOP,
SCU_WATCHDOG_KEEPALIVE,
};
static inline int wdt_command(int sub, u32 *in, int inlen)
{
return intel_scu_ipc_command(IPC_WATCHDOG, sub, in, inlen, NULL, 0);
}
static int wdt_start(struct watchdog_device *wd)
{
struct device *dev = watchdog_get_drvdata(wd);
int ret, in_size;
int timeout = wd->timeout;
struct ipc_wd_start {
u32 pretimeout;
u32 timeout;
} ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
/*
* SCU expects the input size for watchdog IPC to
* be based on 4 bytes
*/
in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);
ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size);
if (ret)
dev_crit(dev, "error starting watchdog: %d\n", ret);
return ret;
}
static int wdt_ping(struct watchdog_device *wd)
{
struct device *dev = watchdog_get_drvdata(wd);
int ret;
ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0);
if (ret)
dev_crit(dev, "Error executing keepalive: %d\n", ret);
return ret;
}
static int wdt_stop(struct watchdog_device *wd)
{
struct device *dev = watchdog_get_drvdata(wd);
int ret;
ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0);
if (ret)
dev_crit(dev, "Error stopping watchdog: %d\n", ret);
return ret;
}
static irqreturn_t mid_wdt_irq(int irq, void *dev_id)
{
panic("Kernel Watchdog");
/* This code should not be reached */
return IRQ_HANDLED;
}
static const struct watchdog_info mid_wdt_info = {
.identity = "Intel MID SCU watchdog",
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
};
static const struct watchdog_ops mid_wdt_ops = {
.owner = THIS_MODULE,
.start = wdt_start,
.stop = wdt_stop,
.ping = wdt_ping,
};
static int mid_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct watchdog_device *wdt_dev;
struct intel_mid_wdt_pdata *pdata = dev->platform_data;
int ret;
if (!pdata) {
dev_err(dev, "missing platform data\n");
return -EINVAL;
}
if (pdata->probe) {
ret = pdata->probe(pdev);
if (ret)
return ret;
}
wdt_dev = devm_kzalloc(dev, sizeof(*wdt_dev), GFP_KERNEL);
if (!wdt_dev)
return -ENOMEM;
wdt_dev->info = &mid_wdt_info;
wdt_dev->ops = &mid_wdt_ops;
wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
wdt_dev->parent = dev;
watchdog_set_drvdata(wdt_dev, dev);
ret = devm_request_irq(dev, pdata->irq, mid_wdt_irq,
IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
wdt_dev);
if (ret) {
dev_err(dev, "error requesting warning irq %d\n", pdata->irq);
return ret;
}
/*
* The firmware followed by U-Boot leaves the watchdog running
* with the default threshold which may vary. When we get here
* we should make a decision to prevent any side effects before
* user space daemon will take care of it. The best option,
* taking into consideration that there is no way to read values
* back from hardware, is to enforce watchdog being run with
* deterministic values.
*/
ret = wdt_start(wdt_dev);
if (ret)
return ret;
/* Make sure the watchdog is serviced */
set_bit(WDOG_HW_RUNNING, &wdt_dev->status);
ret = devm_watchdog_register_device(dev, wdt_dev);
if (ret) {
dev_err(dev, "error registering watchdog device\n");
return ret;
}
dev_info(dev, "Intel MID watchdog device probed\n");
return 0;
}
static struct platform_driver mid_wdt_driver = {
.probe = mid_wdt_probe,
.driver = {
.name = "intel_mid_wdt",
},
};
module_platform_driver(mid_wdt_driver);
MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
MODULE_LICENSE("GPL");
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