1 /* 2 * Watchdog driver for TS-4800 based boards 3 * 4 * Copyright (c) 2015 - Savoir-faire Linux 5 * 6 * This file is licensed under the terms of the GNU General Public 7 * License version 2. This program is licensed "as is" without any 8 * warranty of any kind, whether express or implied. 9 */ 10 11 #include <linux/kernel.h> 12 #include <linux/mfd/syscon.h> 13 #include <linux/module.h> 14 #include <linux/of.h> 15 #include <linux/platform_device.h> 16 #include <linux/regmap.h> 17 #include <linux/watchdog.h> 18 19 static bool nowayout = WATCHDOG_NOWAYOUT; 20 module_param(nowayout, bool, 0); 21 MODULE_PARM_DESC(nowayout, 22 "Watchdog cannot be stopped once started (default=" 23 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 24 25 /* possible feed values */ 26 #define TS4800_WDT_FEED_2S 0x1 27 #define TS4800_WDT_FEED_10S 0x2 28 #define TS4800_WDT_DISABLE 0x3 29 30 struct ts4800_wdt { 31 struct watchdog_device wdd; 32 struct regmap *regmap; 33 u32 feed_offset; 34 u32 feed_val; 35 }; 36 37 /* 38 * TS-4800 supports the following timeout values: 39 * 40 * value desc 41 * --------------------- 42 * 0 feed for 338ms 43 * 1 feed for 2.706s 44 * 2 feed for 10.824s 45 * 3 disable watchdog 46 * 47 * Keep the regmap/timeout map ordered by timeout 48 */ 49 static const struct { 50 const int timeout; 51 const int regval; 52 } ts4800_wdt_map[] = { 53 { 2, TS4800_WDT_FEED_2S }, 54 { 10, TS4800_WDT_FEED_10S }, 55 }; 56 57 #define MAX_TIMEOUT_INDEX (ARRAY_SIZE(ts4800_wdt_map) - 1) 58 59 static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val) 60 { 61 regmap_write(wdt->regmap, wdt->feed_offset, val); 62 } 63 64 static int ts4800_wdt_start(struct watchdog_device *wdd) 65 { 66 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd); 67 68 ts4800_write_feed(wdt, wdt->feed_val); 69 return 0; 70 } 71 72 static int ts4800_wdt_stop(struct watchdog_device *wdd) 73 { 74 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd); 75 76 ts4800_write_feed(wdt, TS4800_WDT_DISABLE); 77 return 0; 78 } 79 80 static int ts4800_wdt_set_timeout(struct watchdog_device *wdd, 81 unsigned int timeout) 82 { 83 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd); 84 int i; 85 86 for (i = 0; i < MAX_TIMEOUT_INDEX; i++) { 87 if (ts4800_wdt_map[i].timeout >= timeout) 88 break; 89 } 90 91 wdd->timeout = ts4800_wdt_map[i].timeout; 92 wdt->feed_val = ts4800_wdt_map[i].regval; 93 94 return 0; 95 } 96 97 static const struct watchdog_ops ts4800_wdt_ops = { 98 .owner = THIS_MODULE, 99 .start = ts4800_wdt_start, 100 .stop = ts4800_wdt_stop, 101 .set_timeout = ts4800_wdt_set_timeout, 102 }; 103 104 static const struct watchdog_info ts4800_wdt_info = { 105 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, 106 .identity = "TS-4800 Watchdog", 107 }; 108 109 static int ts4800_wdt_probe(struct platform_device *pdev) 110 { 111 struct device *dev = &pdev->dev; 112 struct device_node *np = dev->of_node; 113 struct device_node *syscon_np; 114 struct watchdog_device *wdd; 115 struct ts4800_wdt *wdt; 116 u32 reg; 117 int ret; 118 119 syscon_np = of_parse_phandle(np, "syscon", 0); 120 if (!syscon_np) { 121 dev_err(dev, "no syscon property\n"); 122 return -ENODEV; 123 } 124 125 ret = of_property_read_u32_index(np, "syscon", 1, ®); 126 if (ret < 0) { 127 dev_err(dev, "no offset in syscon\n"); 128 of_node_put(syscon_np); 129 return ret; 130 } 131 132 /* allocate memory for watchdog struct */ 133 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 134 if (!wdt) { 135 of_node_put(syscon_np); 136 return -ENOMEM; 137 } 138 139 /* set regmap and offset to know where to write */ 140 wdt->feed_offset = reg; 141 wdt->regmap = syscon_node_to_regmap(syscon_np); 142 of_node_put(syscon_np); 143 if (IS_ERR(wdt->regmap)) { 144 dev_err(dev, "cannot get parent's regmap\n"); 145 return PTR_ERR(wdt->regmap); 146 } 147 148 /* Initialize struct watchdog_device */ 149 wdd = &wdt->wdd; 150 wdd->parent = dev; 151 wdd->info = &ts4800_wdt_info; 152 wdd->ops = &ts4800_wdt_ops; 153 wdd->min_timeout = ts4800_wdt_map[0].timeout; 154 wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout; 155 156 watchdog_set_drvdata(wdd, wdt); 157 watchdog_set_nowayout(wdd, nowayout); 158 watchdog_init_timeout(wdd, 0, dev); 159 160 /* 161 * As this watchdog supports only a few values, ts4800_wdt_set_timeout 162 * must be called to initialize timeout and feed_val with valid values. 163 * Default to maximum timeout if none, or an invalid one, is provided in 164 * device tree. 165 */ 166 if (!wdd->timeout) 167 wdd->timeout = wdd->max_timeout; 168 ts4800_wdt_set_timeout(wdd, wdd->timeout); 169 170 /* 171 * The feed register is write-only, so it is not possible to determine 172 * watchdog's state. Disable it to be in a known state. 173 */ 174 ts4800_wdt_stop(wdd); 175 176 ret = devm_watchdog_register_device(dev, wdd); 177 if (ret) 178 return ret; 179 180 platform_set_drvdata(pdev, wdt); 181 182 dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n", 183 wdd->timeout, nowayout); 184 185 return 0; 186 } 187 188 static const struct of_device_id ts4800_wdt_of_match[] = { 189 { .compatible = "technologic,ts4800-wdt", }, 190 { }, 191 }; 192 MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match); 193 194 static struct platform_driver ts4800_wdt_driver = { 195 .probe = ts4800_wdt_probe, 196 .driver = { 197 .name = "ts4800_wdt", 198 .of_match_table = ts4800_wdt_of_match, 199 }, 200 }; 201 202 module_platform_driver(ts4800_wdt_driver); 203 204 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>"); 205 MODULE_LICENSE("GPL v2"); 206 MODULE_ALIAS("platform:ts4800_wdt"); 207