1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * drivers/char/watchdog/max63xx_wdt.c 4 * 5 * Driver for max63{69,70,71,72,73,74} watchdog timers 6 * 7 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org> 8 * 9 * This driver assumes the watchdog pins are memory mapped (as it is 10 * the case for the Arcom Zeus). Should it be connected over GPIOs or 11 * another interface, some abstraction will have to be introduced. 12 */ 13 14 #include <linux/err.h> 15 #include <linux/module.h> 16 #include <linux/moduleparam.h> 17 #include <linux/mod_devicetable.h> 18 #include <linux/types.h> 19 #include <linux/kernel.h> 20 #include <linux/watchdog.h> 21 #include <linux/bitops.h> 22 #include <linux/platform_device.h> 23 #include <linux/spinlock.h> 24 #include <linux/io.h> 25 #include <linux/slab.h> 26 #include <linux/property.h> 27 28 #define DEFAULT_HEARTBEAT 60 29 #define MAX_HEARTBEAT 60 30 31 static unsigned int heartbeat = DEFAULT_HEARTBEAT; 32 static bool nowayout = WATCHDOG_NOWAYOUT; 33 34 /* 35 * Memory mapping: a single byte, 3 first lower bits to select bit 3 36 * to ping the watchdog. 37 */ 38 #define MAX6369_WDSET (7 << 0) 39 #define MAX6369_WDI (1 << 3) 40 41 #define MAX6369_WDSET_DISABLED 3 42 43 static int nodelay; 44 45 struct max63xx_wdt { 46 struct watchdog_device wdd; 47 const struct max63xx_timeout *timeout; 48 49 /* memory mapping */ 50 void __iomem *base; 51 spinlock_t lock; 52 53 /* WDI and WSET bits write access routines */ 54 void (*ping)(struct max63xx_wdt *wdt); 55 void (*set)(struct max63xx_wdt *wdt, u8 set); 56 }; 57 58 /* 59 * The timeout values used are actually the absolute minimum the chip 60 * offers. Typical values on my board are slightly over twice as long 61 * (10s setting ends up with a 25s timeout), and can be up to 3 times 62 * the nominal setting (according to the datasheet). So please take 63 * these values with a grain of salt. Same goes for the initial delay 64 * "feature". Only max6373/74 have a few settings without this initial 65 * delay (selected with the "nodelay" parameter). 66 * 67 * I also decided to remove from the tables any timeout smaller than a 68 * second, as it looked completly overkill... 69 */ 70 71 /* Timeouts in second */ 72 struct max63xx_timeout { 73 const u8 wdset; 74 const u8 tdelay; 75 const u8 twd; 76 }; 77 78 static const struct max63xx_timeout max6369_table[] = { 79 { 5, 1, 1 }, 80 { 6, 10, 10 }, 81 { 7, 60, 60 }, 82 { }, 83 }; 84 85 static const struct max63xx_timeout max6371_table[] = { 86 { 6, 60, 3 }, 87 { 7, 60, 60 }, 88 { }, 89 }; 90 91 static const struct max63xx_timeout max6373_table[] = { 92 { 2, 60, 1 }, 93 { 5, 0, 1 }, 94 { 1, 3, 3 }, 95 { 7, 60, 10 }, 96 { 6, 0, 10 }, 97 { }, 98 }; 99 100 static const struct max63xx_timeout * 101 max63xx_select_timeout(const struct max63xx_timeout *table, int value) 102 { 103 while (table->twd) { 104 if (value <= table->twd) { 105 if (nodelay && table->tdelay == 0) 106 return table; 107 108 if (!nodelay) 109 return table; 110 } 111 112 table++; 113 } 114 115 return NULL; 116 } 117 118 static int max63xx_wdt_ping(struct watchdog_device *wdd) 119 { 120 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 121 122 wdt->ping(wdt); 123 return 0; 124 } 125 126 static int max63xx_wdt_start(struct watchdog_device *wdd) 127 { 128 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 129 130 wdt->set(wdt, wdt->timeout->wdset); 131 132 /* check for a edge triggered startup */ 133 if (wdt->timeout->tdelay == 0) 134 wdt->ping(wdt); 135 return 0; 136 } 137 138 static int max63xx_wdt_stop(struct watchdog_device *wdd) 139 { 140 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 141 142 wdt->set(wdt, MAX6369_WDSET_DISABLED); 143 return 0; 144 } 145 146 static const struct watchdog_ops max63xx_wdt_ops = { 147 .owner = THIS_MODULE, 148 .start = max63xx_wdt_start, 149 .stop = max63xx_wdt_stop, 150 .ping = max63xx_wdt_ping, 151 }; 152 153 static const struct watchdog_info max63xx_wdt_info = { 154 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 155 .identity = "max63xx Watchdog", 156 }; 157 158 static void max63xx_mmap_ping(struct max63xx_wdt *wdt) 159 { 160 u8 val; 161 162 spin_lock(&wdt->lock); 163 164 val = __raw_readb(wdt->base); 165 166 __raw_writeb(val | MAX6369_WDI, wdt->base); 167 __raw_writeb(val & ~MAX6369_WDI, wdt->base); 168 169 spin_unlock(&wdt->lock); 170 } 171 172 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set) 173 { 174 u8 val; 175 176 spin_lock(&wdt->lock); 177 178 val = __raw_readb(wdt->base); 179 val &= ~MAX6369_WDSET; 180 val |= set & MAX6369_WDSET; 181 __raw_writeb(val, wdt->base); 182 183 spin_unlock(&wdt->lock); 184 } 185 186 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt) 187 { 188 wdt->base = devm_platform_ioremap_resource(p, 0); 189 if (IS_ERR(wdt->base)) 190 return PTR_ERR(wdt->base); 191 192 spin_lock_init(&wdt->lock); 193 194 wdt->ping = max63xx_mmap_ping; 195 wdt->set = max63xx_mmap_set; 196 return 0; 197 } 198 199 static int max63xx_wdt_probe(struct platform_device *pdev) 200 { 201 struct device *dev = &pdev->dev; 202 struct max63xx_wdt *wdt; 203 const struct max63xx_timeout *table; 204 int err; 205 206 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 207 if (!wdt) 208 return -ENOMEM; 209 210 /* Attempt to use fwnode first */ 211 table = device_get_match_data(dev); 212 if (!table) 213 table = (struct max63xx_timeout *)pdev->id_entry->driver_data; 214 215 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT) 216 heartbeat = DEFAULT_HEARTBEAT; 217 218 wdt->timeout = max63xx_select_timeout(table, heartbeat); 219 if (!wdt->timeout) { 220 dev_err(dev, "unable to satisfy %ds heartbeat request\n", 221 heartbeat); 222 return -EINVAL; 223 } 224 225 err = max63xx_mmap_init(pdev, wdt); 226 if (err) 227 return err; 228 229 platform_set_drvdata(pdev, &wdt->wdd); 230 watchdog_set_drvdata(&wdt->wdd, wdt); 231 232 wdt->wdd.parent = dev; 233 wdt->wdd.timeout = wdt->timeout->twd; 234 wdt->wdd.info = &max63xx_wdt_info; 235 wdt->wdd.ops = &max63xx_wdt_ops; 236 237 watchdog_set_nowayout(&wdt->wdd, nowayout); 238 239 err = devm_watchdog_register_device(dev, &wdt->wdd); 240 if (err) 241 return err; 242 243 dev_info(dev, "using %ds heartbeat with %ds initial delay\n", 244 wdt->timeout->twd, wdt->timeout->tdelay); 245 return 0; 246 } 247 248 static const struct platform_device_id max63xx_id_table[] = { 249 { "max6369_wdt", (kernel_ulong_t)max6369_table, }, 250 { "max6370_wdt", (kernel_ulong_t)max6369_table, }, 251 { "max6371_wdt", (kernel_ulong_t)max6371_table, }, 252 { "max6372_wdt", (kernel_ulong_t)max6371_table, }, 253 { "max6373_wdt", (kernel_ulong_t)max6373_table, }, 254 { "max6374_wdt", (kernel_ulong_t)max6373_table, }, 255 { }, 256 }; 257 MODULE_DEVICE_TABLE(platform, max63xx_id_table); 258 259 static const struct of_device_id max63xx_dt_id_table[] = { 260 { .compatible = "maxim,max6369", .data = max6369_table, }, 261 { .compatible = "maxim,max6370", .data = max6369_table, }, 262 { .compatible = "maxim,max6371", .data = max6371_table, }, 263 { .compatible = "maxim,max6372", .data = max6371_table, }, 264 { .compatible = "maxim,max6373", .data = max6373_table, }, 265 { .compatible = "maxim,max6374", .data = max6373_table, }, 266 { } 267 }; 268 MODULE_DEVICE_TABLE(of, max63xx_dt_id_table); 269 270 static struct platform_driver max63xx_wdt_driver = { 271 .probe = max63xx_wdt_probe, 272 .id_table = max63xx_id_table, 273 .driver = { 274 .name = "max63xx_wdt", 275 .of_match_table = max63xx_dt_id_table, 276 }, 277 }; 278 279 module_platform_driver(max63xx_wdt_driver); 280 281 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>"); 282 MODULE_DESCRIPTION("max63xx Watchdog Driver"); 283 284 module_param(heartbeat, int, 0); 285 MODULE_PARM_DESC(heartbeat, 286 "Watchdog heartbeat period in seconds from 1 to " 287 __MODULE_STRING(MAX_HEARTBEAT) ", default " 288 __MODULE_STRING(DEFAULT_HEARTBEAT)); 289 290 module_param(nowayout, bool, 0); 291 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 292 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 293 294 module_param(nodelay, int, 0); 295 MODULE_PARM_DESC(nodelay, 296 "Force selection of a timeout setting without initial delay " 297 "(max6373/74 only, default=0)"); 298 299 MODULE_LICENSE("GPL v2"); 300