/* * 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");