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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * intel-mid_wdt: generic Intel MID SCU watchdog driver4 *5 * Platforms supported so far:6 * - Merrifield only7 *8 * Copyright (C) 2014 Intel Corporation. All rights reserved.9 * Contact: David Cohen <david.a.cohen@linux.intel.com>10 */11 12#include <linux/bitops.h>13#include <linux/device.h>14#include <linux/errno.h>15#include <linux/interrupt.h>16#include <linux/math.h>17#include <linux/module.h>18#include <linux/panic.h>19#include <linux/platform_device.h>20#include <linux/types.h>21#include <linux/watchdog.h>22 23#include <linux/platform_data/x86/intel-mid_wdt.h>24#include <linux/platform_data/x86/intel_scu_ipc.h>25 26#define IPC_WATCHDOG 0xf827 28#define MID_WDT_PRETIMEOUT 1529#define MID_WDT_TIMEOUT_MIN (1 + MID_WDT_PRETIMEOUT)30#define MID_WDT_TIMEOUT_MAX 17031#define MID_WDT_DEFAULT_TIMEOUT 9032 33/* SCU watchdog messages */34enum {35 SCU_WATCHDOG_START = 0,36 SCU_WATCHDOG_STOP,37 SCU_WATCHDOG_KEEPALIVE,38};39 40struct mid_wdt {41 struct watchdog_device wd;42 struct device *dev;43 struct intel_scu_ipc_dev *scu;44};45 46static inline int47wdt_command(struct mid_wdt *mid, int sub, const void *in, size_t inlen, size_t size)48{49 struct intel_scu_ipc_dev *scu = mid->scu;50 51 return intel_scu_ipc_dev_command_with_size(scu, IPC_WATCHDOG, sub, in,52 inlen, size, NULL, 0);53}54 55static int wdt_start(struct watchdog_device *wd)56{57 struct mid_wdt *mid = watchdog_get_drvdata(wd);58 int ret, in_size;59 int timeout = wd->timeout;60 struct ipc_wd_start {61 u32 pretimeout;62 u32 timeout;63 } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };64 65 /*66 * SCU expects the input size for watchdog IPC to be 2 which is the67 * size of the structure in dwords. SCU IPC normally takes bytes68 * but this is a special case where we specify size to be different69 * than inlen.70 */71 in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4);72 73 ret = wdt_command(mid, SCU_WATCHDOG_START, &ipc_wd_start,74 sizeof(ipc_wd_start), in_size);75 if (ret)76 dev_crit(mid->dev, "error starting watchdog: %d\n", ret);77 78 return ret;79}80 81static int wdt_ping(struct watchdog_device *wd)82{83 struct mid_wdt *mid = watchdog_get_drvdata(wd);84 int ret;85 86 ret = wdt_command(mid, SCU_WATCHDOG_KEEPALIVE, NULL, 0, 0);87 if (ret)88 dev_crit(mid->dev, "Error executing keepalive: %d\n", ret);89 90 return ret;91}92 93static int wdt_stop(struct watchdog_device *wd)94{95 struct mid_wdt *mid = watchdog_get_drvdata(wd);96 int ret;97 98 ret = wdt_command(mid, SCU_WATCHDOG_STOP, NULL, 0, 0);99 if (ret)100 dev_crit(mid->dev, "Error stopping watchdog: %d\n", ret);101 102 return ret;103}104 105static irqreturn_t mid_wdt_irq(int irq, void *dev_id)106{107 panic("Kernel Watchdog");108 109 /* This code should not be reached */110 return IRQ_HANDLED;111}112 113static const struct watchdog_info mid_wdt_info = {114 .identity = "Intel MID SCU watchdog",115 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,116};117 118static const struct watchdog_ops mid_wdt_ops = {119 .owner = THIS_MODULE,120 .start = wdt_start,121 .stop = wdt_stop,122 .ping = wdt_ping,123};124 125static int mid_wdt_probe(struct platform_device *pdev)126{127 struct device *dev = &pdev->dev;128 struct watchdog_device *wdt_dev;129 struct intel_mid_wdt_pdata *pdata = dev_get_platdata(dev);130 struct mid_wdt *mid;131 int ret;132 133 if (!pdata) {134 dev_err(dev, "missing platform data\n");135 return -EINVAL;136 }137 138 if (pdata->probe) {139 ret = pdata->probe(pdev);140 if (ret)141 return ret;142 }143 144 mid = devm_kzalloc(dev, sizeof(*mid), GFP_KERNEL);145 if (!mid)146 return -ENOMEM;147 148 mid->dev = dev;149 wdt_dev = &mid->wd;150 151 wdt_dev->info = &mid_wdt_info;152 wdt_dev->ops = &mid_wdt_ops;153 wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;154 wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;155 wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;156 wdt_dev->parent = dev;157 158 watchdog_set_nowayout(wdt_dev, WATCHDOG_NOWAYOUT);159 watchdog_set_drvdata(wdt_dev, mid);160 161 mid->scu = devm_intel_scu_ipc_dev_get(dev);162 if (!mid->scu)163 return -EPROBE_DEFER;164 165 ret = devm_request_irq(dev, pdata->irq, mid_wdt_irq,166 IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",167 wdt_dev);168 if (ret) {169 dev_err(dev, "error requesting warning irq %d\n", pdata->irq);170 return ret;171 }172 173 /*174 * The firmware followed by U-Boot leaves the watchdog running175 * with the default threshold which may vary. When we get here176 * we should make a decision to prevent any side effects before177 * user space daemon will take care of it. The best option,178 * taking into consideration that there is no way to read values179 * back from hardware, is to enforce watchdog being run with180 * deterministic values.181 */182 ret = wdt_start(wdt_dev);183 if (ret)184 return ret;185 186 /* Make sure the watchdog is serviced */187 set_bit(WDOG_HW_RUNNING, &wdt_dev->status);188 189 ret = devm_watchdog_register_device(dev, wdt_dev);190 if (ret)191 return ret;192 193 dev_info(dev, "Intel MID watchdog device probed\n");194 195 return 0;196}197 198static struct platform_driver mid_wdt_driver = {199 .probe = mid_wdt_probe,200 .driver = {201 .name = "intel_mid_wdt",202 },203};204 205module_platform_driver(mid_wdt_driver);206 207MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");208MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");209MODULE_LICENSE("GPL");210MODULE_ALIAS("platform:intel_mid_wdt");211