1 /* 2 * drivers/char/watchdog/max63xx_wdt.c 3 * 4 * Driver for max63{69,70,71,72,73,74} watchdog timers 5 * 6 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org> 7 * 8 * This file is licensed under the terms of the GNU General Public 9 * License version 2. This program is licensed "as is" without any 10 * warranty of any kind, whether express or implied. 11 * 12 * This driver assumes the watchdog pins are memory mapped (as it is 13 * the case for the Arcom Zeus). Should it be connected over GPIOs or 14 * another interface, some abstraction will have to be introduced. 15 */ 16 17 #include <linux/err.h> 18 #include <linux/module.h> 19 #include <linux/moduleparam.h> 20 #include <linux/types.h> 21 #include <linux/kernel.h> 22 #include <linux/watchdog.h> 23 #include <linux/init.h> 24 #include <linux/bitops.h> 25 #include <linux/platform_device.h> 26 #include <linux/spinlock.h> 27 #include <linux/io.h> 28 #include <linux/slab.h> 29 30 #define DEFAULT_HEARTBEAT 60 31 #define MAX_HEARTBEAT 60 32 33 static unsigned int heartbeat = DEFAULT_HEARTBEAT; 34 static bool nowayout = WATCHDOG_NOWAYOUT; 35 36 /* 37 * Memory mapping: a single byte, 3 first lower bits to select bit 3 38 * to ping the watchdog. 39 */ 40 #define MAX6369_WDSET (7 << 0) 41 #define MAX6369_WDI (1 << 3) 42 43 static DEFINE_SPINLOCK(io_lock); 44 45 static int nodelay; 46 static void __iomem *wdt_base; 47 48 /* 49 * The timeout values used are actually the absolute minimum the chip 50 * offers. Typical values on my board are slightly over twice as long 51 * (10s setting ends up with a 25s timeout), and can be up to 3 times 52 * the nominal setting (according to the datasheet). So please take 53 * these values with a grain of salt. Same goes for the initial delay 54 * "feature". Only max6373/74 have a few settings without this initial 55 * delay (selected with the "nodelay" parameter). 56 * 57 * I also decided to remove from the tables any timeout smaller than a 58 * second, as it looked completly overkill... 59 */ 60 61 /* Timeouts in second */ 62 struct max63xx_timeout { 63 u8 wdset; 64 u8 tdelay; 65 u8 twd; 66 }; 67 68 static struct max63xx_timeout max6369_table[] = { 69 { 5, 1, 1 }, 70 { 6, 10, 10 }, 71 { 7, 60, 60 }, 72 { }, 73 }; 74 75 static struct max63xx_timeout max6371_table[] = { 76 { 6, 60, 3 }, 77 { 7, 60, 60 }, 78 { }, 79 }; 80 81 static struct max63xx_timeout max6373_table[] = { 82 { 2, 60, 1 }, 83 { 5, 0, 1 }, 84 { 1, 3, 3 }, 85 { 7, 60, 10 }, 86 { 6, 0, 10 }, 87 { }, 88 }; 89 90 static struct max63xx_timeout *current_timeout; 91 92 static struct max63xx_timeout * 93 max63xx_select_timeout(struct max63xx_timeout *table, int value) 94 { 95 while (table->twd) { 96 if (value <= table->twd) { 97 if (nodelay && table->tdelay == 0) 98 return table; 99 100 if (!nodelay) 101 return table; 102 } 103 104 table++; 105 } 106 107 return NULL; 108 } 109 110 static int max63xx_wdt_ping(struct watchdog_device *wdd) 111 { 112 u8 val; 113 114 spin_lock(&io_lock); 115 116 val = __raw_readb(wdt_base); 117 118 __raw_writeb(val | MAX6369_WDI, wdt_base); 119 __raw_writeb(val & ~MAX6369_WDI, wdt_base); 120 121 spin_unlock(&io_lock); 122 return 0; 123 } 124 125 static int max63xx_wdt_start(struct watchdog_device *wdd) 126 { 127 struct max63xx_timeout *entry = watchdog_get_drvdata(wdd); 128 u8 val; 129 130 spin_lock(&io_lock); 131 132 val = __raw_readb(wdt_base); 133 val &= ~MAX6369_WDSET; 134 val |= entry->wdset; 135 __raw_writeb(val, wdt_base); 136 137 spin_unlock(&io_lock); 138 139 /* check for a edge triggered startup */ 140 if (entry->tdelay == 0) 141 max63xx_wdt_ping(wdd); 142 return 0; 143 } 144 145 static int max63xx_wdt_stop(struct watchdog_device *wdd) 146 { 147 u8 val; 148 149 spin_lock(&io_lock); 150 151 val = __raw_readb(wdt_base); 152 val &= ~MAX6369_WDSET; 153 val |= 3; 154 __raw_writeb(val, wdt_base); 155 156 spin_unlock(&io_lock); 157 return 0; 158 } 159 160 static const struct watchdog_info max63xx_wdt_info = { 161 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 162 .identity = "max63xx Watchdog", 163 }; 164 165 static const struct watchdog_ops max63xx_wdt_ops = { 166 .owner = THIS_MODULE, 167 .start = max63xx_wdt_start, 168 .stop = max63xx_wdt_stop, 169 .ping = max63xx_wdt_ping, 170 }; 171 172 static struct watchdog_device max63xx_wdt_dev = { 173 .info = &max63xx_wdt_info, 174 .ops = &max63xx_wdt_ops, 175 }; 176 177 static int max63xx_wdt_probe(struct platform_device *pdev) 178 { 179 struct resource *wdt_mem; 180 struct max63xx_timeout *table; 181 182 table = (struct max63xx_timeout *)pdev->id_entry->driver_data; 183 184 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT) 185 heartbeat = DEFAULT_HEARTBEAT; 186 187 dev_info(&pdev->dev, "requesting %ds heartbeat\n", heartbeat); 188 current_timeout = max63xx_select_timeout(table, heartbeat); 189 190 if (!current_timeout) { 191 dev_err(&pdev->dev, "unable to satisfy heartbeat request\n"); 192 return -EINVAL; 193 } 194 195 dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n", 196 current_timeout->twd, current_timeout->tdelay); 197 198 heartbeat = current_timeout->twd; 199 200 wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); 201 wdt_base = devm_ioremap_resource(&pdev->dev, wdt_mem); 202 if (IS_ERR(wdt_base)) 203 return PTR_ERR(wdt_base); 204 205 max63xx_wdt_dev.timeout = heartbeat; 206 watchdog_set_nowayout(&max63xx_wdt_dev, nowayout); 207 watchdog_set_drvdata(&max63xx_wdt_dev, current_timeout); 208 209 return watchdog_register_device(&max63xx_wdt_dev); 210 } 211 212 static int max63xx_wdt_remove(struct platform_device *pdev) 213 { 214 watchdog_unregister_device(&max63xx_wdt_dev); 215 return 0; 216 } 217 218 static struct platform_device_id max63xx_id_table[] = { 219 { "max6369_wdt", (kernel_ulong_t)max6369_table, }, 220 { "max6370_wdt", (kernel_ulong_t)max6369_table, }, 221 { "max6371_wdt", (kernel_ulong_t)max6371_table, }, 222 { "max6372_wdt", (kernel_ulong_t)max6371_table, }, 223 { "max6373_wdt", (kernel_ulong_t)max6373_table, }, 224 { "max6374_wdt", (kernel_ulong_t)max6373_table, }, 225 { }, 226 }; 227 MODULE_DEVICE_TABLE(platform, max63xx_id_table); 228 229 static struct platform_driver max63xx_wdt_driver = { 230 .probe = max63xx_wdt_probe, 231 .remove = max63xx_wdt_remove, 232 .id_table = max63xx_id_table, 233 .driver = { 234 .name = "max63xx_wdt", 235 .owner = THIS_MODULE, 236 }, 237 }; 238 239 module_platform_driver(max63xx_wdt_driver); 240 241 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>"); 242 MODULE_DESCRIPTION("max63xx Watchdog Driver"); 243 244 module_param(heartbeat, int, 0); 245 MODULE_PARM_DESC(heartbeat, 246 "Watchdog heartbeat period in seconds from 1 to " 247 __MODULE_STRING(MAX_HEARTBEAT) ", default " 248 __MODULE_STRING(DEFAULT_HEARTBEAT)); 249 250 module_param(nowayout, bool, 0); 251 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 252 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 253 254 module_param(nodelay, int, 0); 255 MODULE_PARM_DESC(nodelay, 256 "Force selection of a timeout setting without initial delay " 257 "(max6373/74 only, default=0)"); 258 259 MODULE_LICENSE("GPL"); 260