1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Watchdog driver for TS-4800 based boards 4 * 5 * Copyright (c) 2015 - Savoir-faire Linux 6 * 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/mfd/syscon.h> 11 #include <linux/module.h> 12 #include <linux/of.h> 13 #include <linux/platform_device.h> 14 #include <linux/regmap.h> 15 #include <linux/watchdog.h> 16 17 static bool nowayout = WATCHDOG_NOWAYOUT; 18 module_param(nowayout, bool, 0); 19 MODULE_PARM_DESC(nowayout, 20 "Watchdog cannot be stopped once started (default=" 21 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 22 23 /* possible feed values */ 24 #define TS4800_WDT_FEED_2S 0x1 25 #define TS4800_WDT_FEED_10S 0x2 26 #define TS4800_WDT_DISABLE 0x3 27 28 struct ts4800_wdt { 29 struct watchdog_device wdd; 30 struct regmap *regmap; 31 u32 feed_offset; 32 u32 feed_val; 33 }; 34 35 /* 36 * TS-4800 supports the following timeout values: 37 * 38 * value desc 39 * --------------------- 40 * 0 feed for 338ms 41 * 1 feed for 2.706s 42 * 2 feed for 10.824s 43 * 3 disable watchdog 44 * 45 * Keep the regmap/timeout map ordered by timeout 46 */ 47 static const struct { 48 const int timeout; 49 const int regval; 50 } ts4800_wdt_map[] = { 51 { 2, TS4800_WDT_FEED_2S }, 52 { 10, TS4800_WDT_FEED_10S }, 53 }; 54 55 #define MAX_TIMEOUT_INDEX (ARRAY_SIZE(ts4800_wdt_map) - 1) 56 57 static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val) 58 { 59 regmap_write(wdt->regmap, wdt->feed_offset, val); 60 } 61 62 static int ts4800_wdt_start(struct watchdog_device *wdd) 63 { 64 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd); 65 66 ts4800_write_feed(wdt, wdt->feed_val); 67 return 0; 68 } 69 70 static int ts4800_wdt_stop(struct watchdog_device *wdd) 71 { 72 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd); 73 74 ts4800_write_feed(wdt, TS4800_WDT_DISABLE); 75 return 0; 76 } 77 78 static int ts4800_wdt_set_timeout(struct watchdog_device *wdd, 79 unsigned int timeout) 80 { 81 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd); 82 int i; 83 84 for (i = 0; i < MAX_TIMEOUT_INDEX; i++) { 85 if (ts4800_wdt_map[i].timeout >= timeout) 86 break; 87 } 88 89 wdd->timeout = ts4800_wdt_map[i].timeout; 90 wdt->feed_val = ts4800_wdt_map[i].regval; 91 92 return 0; 93 } 94 95 static const struct watchdog_ops ts4800_wdt_ops = { 96 .owner = THIS_MODULE, 97 .start = ts4800_wdt_start, 98 .stop = ts4800_wdt_stop, 99 .set_timeout = ts4800_wdt_set_timeout, 100 }; 101 102 static const struct watchdog_info ts4800_wdt_info = { 103 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING, 104 .identity = "TS-4800 Watchdog", 105 }; 106 107 static int ts4800_wdt_probe(struct platform_device *pdev) 108 { 109 struct device *dev = &pdev->dev; 110 struct device_node *np = dev->of_node; 111 struct device_node *syscon_np; 112 struct watchdog_device *wdd; 113 struct ts4800_wdt *wdt; 114 u32 reg; 115 int ret; 116 117 syscon_np = of_parse_phandle(np, "syscon", 0); 118 if (!syscon_np) { 119 dev_err(dev, "no syscon property\n"); 120 return -ENODEV; 121 } 122 123 ret = of_property_read_u32_index(np, "syscon", 1, ®); 124 if (ret < 0) { 125 dev_err(dev, "no offset in syscon\n"); 126 of_node_put(syscon_np); 127 return ret; 128 } 129 130 /* allocate memory for watchdog struct */ 131 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 132 if (!wdt) { 133 of_node_put(syscon_np); 134 return -ENOMEM; 135 } 136 137 /* set regmap and offset to know where to write */ 138 wdt->feed_offset = reg; 139 wdt->regmap = syscon_node_to_regmap(syscon_np); 140 of_node_put(syscon_np); 141 if (IS_ERR(wdt->regmap)) { 142 dev_err(dev, "cannot get parent's regmap\n"); 143 return PTR_ERR(wdt->regmap); 144 } 145 146 /* Initialize struct watchdog_device */ 147 wdd = &wdt->wdd; 148 wdd->parent = dev; 149 wdd->info = &ts4800_wdt_info; 150 wdd->ops = &ts4800_wdt_ops; 151 wdd->min_timeout = ts4800_wdt_map[0].timeout; 152 wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout; 153 154 watchdog_set_drvdata(wdd, wdt); 155 watchdog_set_nowayout(wdd, nowayout); 156 watchdog_init_timeout(wdd, 0, dev); 157 158 /* 159 * As this watchdog supports only a few values, ts4800_wdt_set_timeout 160 * must be called to initialize timeout and feed_val with valid values. 161 * Default to maximum timeout if none, or an invalid one, is provided in 162 * device tree. 163 */ 164 if (!wdd->timeout) 165 wdd->timeout = wdd->max_timeout; 166 ts4800_wdt_set_timeout(wdd, wdd->timeout); 167 168 /* 169 * The feed register is write-only, so it is not possible to determine 170 * watchdog's state. Disable it to be in a known state. 171 */ 172 ts4800_wdt_stop(wdd); 173 174 ret = devm_watchdog_register_device(dev, wdd); 175 if (ret) 176 return ret; 177 178 platform_set_drvdata(pdev, wdt); 179 180 dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n", 181 wdd->timeout, nowayout); 182 183 return 0; 184 } 185 186 static const struct of_device_id ts4800_wdt_of_match[] = { 187 { .compatible = "technologic,ts4800-wdt", }, 188 { }, 189 }; 190 MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match); 191 192 static struct platform_driver ts4800_wdt_driver = { 193 .probe = ts4800_wdt_probe, 194 .driver = { 195 .name = "ts4800_wdt", 196 .of_match_table = ts4800_wdt_of_match, 197 }, 198 }; 199 200 module_platform_driver(ts4800_wdt_driver); 201 202 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>"); 203 MODULE_LICENSE("GPL v2"); 204 MODULE_ALIAS("platform:ts4800_wdt"); 205