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/bitops.h> 24 #include <linux/platform_device.h> 25 #include <linux/spinlock.h> 26 #include <linux/io.h> 27 #include <linux/slab.h> 28 29 #define DEFAULT_HEARTBEAT 60 30 #define MAX_HEARTBEAT 60 31 32 static unsigned int heartbeat = DEFAULT_HEARTBEAT; 33 static bool nowayout = WATCHDOG_NOWAYOUT; 34 35 /* 36 * Memory mapping: a single byte, 3 first lower bits to select bit 3 37 * to ping the watchdog. 38 */ 39 #define MAX6369_WDSET (7 << 0) 40 #define MAX6369_WDI (1 << 3) 41 42 #define MAX6369_WDSET_DISABLED 3 43 44 static int nodelay; 45 46 struct max63xx_wdt { 47 struct watchdog_device wdd; 48 const struct max63xx_timeout *timeout; 49 50 /* memory mapping */ 51 void __iomem *base; 52 spinlock_t lock; 53 54 /* WDI and WSET bits write access routines */ 55 void (*ping)(struct max63xx_wdt *wdt); 56 void (*set)(struct max63xx_wdt *wdt, u8 set); 57 }; 58 59 /* 60 * The timeout values used are actually the absolute minimum the chip 61 * offers. Typical values on my board are slightly over twice as long 62 * (10s setting ends up with a 25s timeout), and can be up to 3 times 63 * the nominal setting (according to the datasheet). So please take 64 * these values with a grain of salt. Same goes for the initial delay 65 * "feature". Only max6373/74 have a few settings without this initial 66 * delay (selected with the "nodelay" parameter). 67 * 68 * I also decided to remove from the tables any timeout smaller than a 69 * second, as it looked completly overkill... 70 */ 71 72 /* Timeouts in second */ 73 struct max63xx_timeout { 74 const u8 wdset; 75 const u8 tdelay; 76 const u8 twd; 77 }; 78 79 static const struct max63xx_timeout max6369_table[] = { 80 { 5, 1, 1 }, 81 { 6, 10, 10 }, 82 { 7, 60, 60 }, 83 { }, 84 }; 85 86 static const struct max63xx_timeout max6371_table[] = { 87 { 6, 60, 3 }, 88 { 7, 60, 60 }, 89 { }, 90 }; 91 92 static const struct max63xx_timeout max6373_table[] = { 93 { 2, 60, 1 }, 94 { 5, 0, 1 }, 95 { 1, 3, 3 }, 96 { 7, 60, 10 }, 97 { 6, 0, 10 }, 98 { }, 99 }; 100 101 static struct max63xx_timeout * 102 max63xx_select_timeout(struct max63xx_timeout *table, int value) 103 { 104 while (table->twd) { 105 if (value <= table->twd) { 106 if (nodelay && table->tdelay == 0) 107 return table; 108 109 if (!nodelay) 110 return table; 111 } 112 113 table++; 114 } 115 116 return NULL; 117 } 118 119 static int max63xx_wdt_ping(struct watchdog_device *wdd) 120 { 121 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 122 123 wdt->ping(wdt); 124 return 0; 125 } 126 127 static int max63xx_wdt_start(struct watchdog_device *wdd) 128 { 129 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 130 131 wdt->set(wdt, wdt->timeout->wdset); 132 133 /* check for a edge triggered startup */ 134 if (wdt->timeout->tdelay == 0) 135 wdt->ping(wdt); 136 return 0; 137 } 138 139 static int max63xx_wdt_stop(struct watchdog_device *wdd) 140 { 141 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 142 143 wdt->set(wdt, MAX6369_WDSET_DISABLED); 144 return 0; 145 } 146 147 static const struct watchdog_ops max63xx_wdt_ops = { 148 .owner = THIS_MODULE, 149 .start = max63xx_wdt_start, 150 .stop = max63xx_wdt_stop, 151 .ping = max63xx_wdt_ping, 152 }; 153 154 static const struct watchdog_info max63xx_wdt_info = { 155 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 156 .identity = "max63xx Watchdog", 157 }; 158 159 static void max63xx_mmap_ping(struct max63xx_wdt *wdt) 160 { 161 u8 val; 162 163 spin_lock(&wdt->lock); 164 165 val = __raw_readb(wdt->base); 166 167 __raw_writeb(val | MAX6369_WDI, wdt->base); 168 __raw_writeb(val & ~MAX6369_WDI, wdt->base); 169 170 spin_unlock(&wdt->lock); 171 } 172 173 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set) 174 { 175 u8 val; 176 177 spin_lock(&wdt->lock); 178 179 val = __raw_readb(wdt->base); 180 val &= ~MAX6369_WDSET; 181 val |= set & MAX6369_WDSET; 182 __raw_writeb(val, wdt->base); 183 184 spin_unlock(&wdt->lock); 185 } 186 187 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt) 188 { 189 struct resource *mem = platform_get_resource(p, IORESOURCE_MEM, 0); 190 191 wdt->base = devm_ioremap_resource(&p->dev, mem); 192 if (IS_ERR(wdt->base)) 193 return PTR_ERR(wdt->base); 194 195 spin_lock_init(&wdt->lock); 196 197 wdt->ping = max63xx_mmap_ping; 198 wdt->set = max63xx_mmap_set; 199 return 0; 200 } 201 202 static int max63xx_wdt_probe(struct platform_device *pdev) 203 { 204 struct max63xx_wdt *wdt; 205 struct max63xx_timeout *table; 206 int err; 207 208 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); 209 if (!wdt) 210 return -ENOMEM; 211 212 table = (struct max63xx_timeout *)pdev->id_entry->driver_data; 213 214 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT) 215 heartbeat = DEFAULT_HEARTBEAT; 216 217 wdt->timeout = max63xx_select_timeout(table, heartbeat); 218 if (!wdt->timeout) { 219 dev_err(&pdev->dev, "unable to satisfy %ds heartbeat request\n", 220 heartbeat); 221 return -EINVAL; 222 } 223 224 err = max63xx_mmap_init(pdev, wdt); 225 if (err) 226 return err; 227 228 platform_set_drvdata(pdev, &wdt->wdd); 229 watchdog_set_drvdata(&wdt->wdd, wdt); 230 231 wdt->wdd.parent = &pdev->dev; 232 wdt->wdd.timeout = wdt->timeout->twd; 233 wdt->wdd.info = &max63xx_wdt_info; 234 wdt->wdd.ops = &max63xx_wdt_ops; 235 236 watchdog_set_nowayout(&wdt->wdd, nowayout); 237 238 err = watchdog_register_device(&wdt->wdd); 239 if (err) 240 return err; 241 242 dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n", 243 wdt->timeout->twd, wdt->timeout->tdelay); 244 return 0; 245 } 246 247 static int max63xx_wdt_remove(struct platform_device *pdev) 248 { 249 struct watchdog_device *wdd = platform_get_drvdata(pdev); 250 251 watchdog_unregister_device(wdd); 252 return 0; 253 } 254 255 static const struct platform_device_id max63xx_id_table[] = { 256 { "max6369_wdt", (kernel_ulong_t)max6369_table, }, 257 { "max6370_wdt", (kernel_ulong_t)max6369_table, }, 258 { "max6371_wdt", (kernel_ulong_t)max6371_table, }, 259 { "max6372_wdt", (kernel_ulong_t)max6371_table, }, 260 { "max6373_wdt", (kernel_ulong_t)max6373_table, }, 261 { "max6374_wdt", (kernel_ulong_t)max6373_table, }, 262 { }, 263 }; 264 MODULE_DEVICE_TABLE(platform, max63xx_id_table); 265 266 static struct platform_driver max63xx_wdt_driver = { 267 .probe = max63xx_wdt_probe, 268 .remove = max63xx_wdt_remove, 269 .id_table = max63xx_id_table, 270 .driver = { 271 .name = "max63xx_wdt", 272 }, 273 }; 274 275 module_platform_driver(max63xx_wdt_driver); 276 277 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>"); 278 MODULE_DESCRIPTION("max63xx Watchdog Driver"); 279 280 module_param(heartbeat, int, 0); 281 MODULE_PARM_DESC(heartbeat, 282 "Watchdog heartbeat period in seconds from 1 to " 283 __MODULE_STRING(MAX_HEARTBEAT) ", default " 284 __MODULE_STRING(DEFAULT_HEARTBEAT)); 285 286 module_param(nowayout, bool, 0); 287 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 288 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 289 290 module_param(nodelay, int, 0); 291 MODULE_PARM_DESC(nodelay, 292 "Force selection of a timeout setting without initial delay " 293 "(max6373/74 only, default=0)"); 294 295 MODULE_LICENSE("GPL"); 296