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 */ 30 enum { 31 SCU_WATCHDOG_START = 0, 32 SCU_WATCHDOG_STOP, 33 SCU_WATCHDOG_KEEPALIVE, 34 }; 35 36 static 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 41 static 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 64 static 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 76 static 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 88 static 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 96 static const struct watchdog_info mid_wdt_info = { 97 .identity = "Intel MID SCU watchdog", 98 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, 99 }; 100 101 static const struct watchdog_ops mid_wdt_ops = { 102 .owner = THIS_MODULE, 103 .start = wdt_start, 104 .stop = wdt_stop, 105 .ping = wdt_ping, 106 }; 107 108 static 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 dev_err(dev, "error registering watchdog device\n"); 166 return ret; 167 } 168 169 dev_info(dev, "Intel MID watchdog device probed\n"); 170 171 return 0; 172 } 173 174 static struct platform_driver mid_wdt_driver = { 175 .probe = mid_wdt_probe, 176 .driver = { 177 .name = "intel_mid_wdt", 178 }, 179 }; 180 181 module_platform_driver(mid_wdt_driver); 182 183 MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>"); 184 MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform"); 185 MODULE_LICENSE("GPL"); 186