1 /* 2 * Watchdog timer driver for the WinSystems EBC-C384 3 * Copyright (C) 2016 William Breathitt Gray 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License, version 2, as 7 * published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it will be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * General Public License for more details. 13 */ 14 #include <linux/device.h> 15 #include <linux/dmi.h> 16 #include <linux/errno.h> 17 #include <linux/io.h> 18 #include <linux/ioport.h> 19 #include <linux/isa.h> 20 #include <linux/kernel.h> 21 #include <linux/module.h> 22 #include <linux/moduleparam.h> 23 #include <linux/types.h> 24 #include <linux/watchdog.h> 25 26 #define MODULE_NAME "ebc-c384_wdt" 27 #define WATCHDOG_TIMEOUT 60 28 /* 29 * The timeout value in minutes must fit in a single byte when sent to the 30 * watchdog timer; the maximum timeout possible is 15300 (255 * 60) seconds. 31 */ 32 #define WATCHDOG_MAX_TIMEOUT 15300 33 #define BASE_ADDR 0x564 34 #define ADDR_EXTENT 5 35 #define CFG_ADDR (BASE_ADDR + 1) 36 #define PET_ADDR (BASE_ADDR + 2) 37 38 static bool nowayout = WATCHDOG_NOWAYOUT; 39 module_param(nowayout, bool, 0); 40 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 41 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 42 43 static unsigned timeout; 44 module_param(timeout, uint, 0); 45 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default=" 46 __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 47 48 static int ebc_c384_wdt_start(struct watchdog_device *wdev) 49 { 50 unsigned t = wdev->timeout; 51 52 /* resolution is in minutes for timeouts greater than 255 seconds */ 53 if (t > 255) 54 t = DIV_ROUND_UP(t, 60); 55 56 outb(t, PET_ADDR); 57 58 return 0; 59 } 60 61 static int ebc_c384_wdt_stop(struct watchdog_device *wdev) 62 { 63 outb(0x00, PET_ADDR); 64 65 return 0; 66 } 67 68 static int ebc_c384_wdt_set_timeout(struct watchdog_device *wdev, unsigned t) 69 { 70 /* resolution is in minutes for timeouts greater than 255 seconds */ 71 if (t > 255) { 72 /* round second resolution up to minute granularity */ 73 wdev->timeout = roundup(t, 60); 74 75 /* set watchdog timer for minutes */ 76 outb(0x00, CFG_ADDR); 77 } else { 78 wdev->timeout = t; 79 80 /* set watchdog timer for seconds */ 81 outb(0x80, CFG_ADDR); 82 } 83 84 return 0; 85 } 86 87 static const struct watchdog_ops ebc_c384_wdt_ops = { 88 .start = ebc_c384_wdt_start, 89 .stop = ebc_c384_wdt_stop, 90 .set_timeout = ebc_c384_wdt_set_timeout 91 }; 92 93 static const struct watchdog_info ebc_c384_wdt_info = { 94 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT, 95 .identity = MODULE_NAME 96 }; 97 98 static int ebc_c384_wdt_probe(struct device *dev, unsigned int id) 99 { 100 struct watchdog_device *wdd; 101 102 if (!devm_request_region(dev, BASE_ADDR, ADDR_EXTENT, dev_name(dev))) { 103 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n", 104 BASE_ADDR, BASE_ADDR + ADDR_EXTENT); 105 return -EBUSY; 106 } 107 108 wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL); 109 if (!wdd) 110 return -ENOMEM; 111 112 wdd->info = &ebc_c384_wdt_info; 113 wdd->ops = &ebc_c384_wdt_ops; 114 wdd->timeout = WATCHDOG_TIMEOUT; 115 wdd->min_timeout = 1; 116 wdd->max_timeout = WATCHDOG_MAX_TIMEOUT; 117 118 watchdog_set_nowayout(wdd, nowayout); 119 120 if (watchdog_init_timeout(wdd, timeout, dev)) 121 dev_warn(dev, "Invalid timeout (%u seconds), using default (%u seconds)\n", 122 timeout, WATCHDOG_TIMEOUT); 123 124 dev_set_drvdata(dev, wdd); 125 126 return watchdog_register_device(wdd); 127 } 128 129 static int ebc_c384_wdt_remove(struct device *dev, unsigned int id) 130 { 131 struct watchdog_device *wdd = dev_get_drvdata(dev); 132 133 watchdog_unregister_device(wdd); 134 135 return 0; 136 } 137 138 static struct isa_driver ebc_c384_wdt_driver = { 139 .probe = ebc_c384_wdt_probe, 140 .driver = { 141 .name = MODULE_NAME 142 }, 143 .remove = ebc_c384_wdt_remove 144 }; 145 146 static int __init ebc_c384_wdt_init(void) 147 { 148 if (!dmi_match(DMI_BOARD_NAME, "EBC-C384 SBC")) 149 return -ENODEV; 150 151 return isa_register_driver(&ebc_c384_wdt_driver, 1); 152 } 153 154 static void __exit ebc_c384_wdt_exit(void) 155 { 156 isa_unregister_driver(&ebc_c384_wdt_driver); 157 } 158 159 module_init(ebc_c384_wdt_init); 160 module_exit(ebc_c384_wdt_exit); 161 162 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>"); 163 MODULE_DESCRIPTION("WinSystems EBC-C384 watchdog timer driver"); 164 MODULE_LICENSE("GPL v2"); 165 MODULE_ALIAS("isa:" MODULE_NAME); 166