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 */ 33 enum { 34 SCU_WATCHDOG_START = 0, 35 SCU_WATCHDOG_STOP, 36 SCU_WATCHDOG_KEEPALIVE, 37 }; 38 39 static 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 44 static int wdt_start(struct watchdog_device *wd) 45 { 46 struct device *dev = watchdog_get_drvdata(wd); 47 int ret, in_size; 48 int timeout = wd->timeout; 49 struct ipc_wd_start { 50 u32 pretimeout; 51 u32 timeout; 52 } ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout }; 53 54 /* 55 * SCU expects the input size for watchdog IPC to 56 * be based on 4 bytes 57 */ 58 in_size = DIV_ROUND_UP(sizeof(ipc_wd_start), 4); 59 60 ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size); 61 if (ret) 62 dev_crit(dev, "error starting watchdog: %d\n", ret); 63 64 return ret; 65 } 66 67 static int wdt_ping(struct watchdog_device *wd) 68 { 69 struct device *dev = watchdog_get_drvdata(wd); 70 int ret; 71 72 ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0); 73 if (ret) 74 dev_crit(dev, "Error executing keepalive: %d\n", ret); 75 76 return ret; 77 } 78 79 static int wdt_stop(struct watchdog_device *wd) 80 { 81 struct device *dev = watchdog_get_drvdata(wd); 82 int ret; 83 84 ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0); 85 if (ret) 86 dev_crit(dev, "Error stopping watchdog: %d\n", ret); 87 88 return ret; 89 } 90 91 static irqreturn_t mid_wdt_irq(int irq, void *dev_id) 92 { 93 panic("Kernel Watchdog"); 94 95 /* This code should not be reached */ 96 return IRQ_HANDLED; 97 } 98 99 static const struct watchdog_info mid_wdt_info = { 100 .identity = "Intel MID SCU watchdog", 101 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, 102 }; 103 104 static const struct watchdog_ops mid_wdt_ops = { 105 .owner = THIS_MODULE, 106 .start = wdt_start, 107 .stop = wdt_stop, 108 .ping = wdt_ping, 109 }; 110 111 static int mid_wdt_probe(struct platform_device *pdev) 112 { 113 struct watchdog_device *wdt_dev; 114 struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data; 115 int ret; 116 117 if (!pdata) { 118 dev_err(&pdev->dev, "missing platform data\n"); 119 return -EINVAL; 120 } 121 122 if (pdata->probe) { 123 ret = pdata->probe(pdev); 124 if (ret) 125 return ret; 126 } 127 128 wdt_dev = devm_kzalloc(&pdev->dev, sizeof(*wdt_dev), GFP_KERNEL); 129 if (!wdt_dev) 130 return -ENOMEM; 131 132 wdt_dev->info = &mid_wdt_info; 133 wdt_dev->ops = &mid_wdt_ops; 134 wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN; 135 wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX; 136 wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT; 137 wdt_dev->parent = &pdev->dev; 138 139 watchdog_set_drvdata(wdt_dev, &pdev->dev); 140 141 ret = devm_request_irq(&pdev->dev, pdata->irq, mid_wdt_irq, 142 IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog", 143 wdt_dev); 144 if (ret) { 145 dev_err(&pdev->dev, "error requesting warning irq %d\n", 146 pdata->irq); 147 return ret; 148 } 149 150 /* 151 * The firmware followed by U-Boot leaves the watchdog running 152 * with the default threshold which may vary. When we get here 153 * we should make a decision to prevent any side effects before 154 * user space daemon will take care of it. The best option, 155 * taking into consideration that there is no way to read values 156 * back from hardware, is to enforce watchdog being run with 157 * deterministic values. 158 */ 159 ret = wdt_start(wdt_dev); 160 if (ret) 161 return ret; 162 163 /* Make sure the watchdog is serviced */ 164 set_bit(WDOG_HW_RUNNING, &wdt_dev->status); 165 166 ret = devm_watchdog_register_device(&pdev->dev, wdt_dev); 167 if (ret) { 168 dev_err(&pdev->dev, "error registering watchdog device\n"); 169 return ret; 170 } 171 172 dev_info(&pdev->dev, "Intel MID watchdog device probed\n"); 173 174 return 0; 175 } 176 177 static struct platform_driver mid_wdt_driver = { 178 .probe = mid_wdt_probe, 179 .driver = { 180 .name = "intel_mid_wdt", 181 }, 182 }; 183 184 module_platform_driver(mid_wdt_driver); 185 186 MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>"); 187 MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform"); 188 MODULE_LICENSE("GPL"); 189