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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright (C) 2020 ROHM Semiconductors4 *5 * ROHM BD9576MUF and BD9573MUF Watchdog driver6 */7 8#include <linux/err.h>9#include <linux/gpio/consumer.h>10#include <linux/mfd/rohm-bd957x.h>11#include <linux/module.h>12#include <linux/platform_device.h>13#include <linux/property.h>14#include <linux/regmap.h>15#include <linux/watchdog.h>16 17static bool nowayout;18module_param(nowayout, bool, 0);19MODULE_PARM_DESC(nowayout,20 "Watchdog cannot be stopped once started (default=\"false\")");21 22#define HW_MARGIN_MIN 223#define HW_MARGIN_MAX 441624#define BD957X_WDT_DEFAULT_MARGIN 441625#define WATCHDOG_TIMEOUT 3026 27struct bd9576_wdt_priv {28 struct gpio_desc *gpiod_ping;29 struct gpio_desc *gpiod_en;30 struct device *dev;31 struct regmap *regmap;32 struct watchdog_device wdd;33};34 35static void bd9576_wdt_disable(struct bd9576_wdt_priv *priv)36{37 gpiod_set_value_cansleep(priv->gpiod_en, 0);38}39 40static int bd9576_wdt_ping(struct watchdog_device *wdd)41{42 struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);43 44 /* Pulse */45 gpiod_set_value_cansleep(priv->gpiod_ping, 1);46 gpiod_set_value_cansleep(priv->gpiod_ping, 0);47 48 return 0;49}50 51static int bd9576_wdt_start(struct watchdog_device *wdd)52{53 struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);54 55 gpiod_set_value_cansleep(priv->gpiod_en, 1);56 57 return bd9576_wdt_ping(wdd);58}59 60static int bd9576_wdt_stop(struct watchdog_device *wdd)61{62 struct bd9576_wdt_priv *priv = watchdog_get_drvdata(wdd);63 64 bd9576_wdt_disable(priv);65 66 return 0;67}68 69static const struct watchdog_info bd957x_wdt_ident = {70 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |71 WDIOF_SETTIMEOUT,72 .identity = "BD957x Watchdog",73};74 75static const struct watchdog_ops bd957x_wdt_ops = {76 .owner = THIS_MODULE,77 .start = bd9576_wdt_start,78 .stop = bd9576_wdt_stop,79 .ping = bd9576_wdt_ping,80};81 82/* Unit is hundreds of uS */83#define FASTNG_MIN 2384 85static int find_closest_fast(int target, int *sel, int *val)86{87 int i;88 int window = FASTNG_MIN;89 90 for (i = 0; i < 8 && window < target; i++)91 window <<= 1;92 93 *val = window;94 *sel = i;95 96 if (i == 8)97 return -EINVAL;98 99 return 0;100 101}102 103static int find_closest_slow_by_fast(int fast_val, int target, int *slowsel)104{105 int sel;106 static const int multipliers[] = {2, 3, 7, 15};107 108 for (sel = 0; sel < ARRAY_SIZE(multipliers) &&109 multipliers[sel] * fast_val < target; sel++)110 ;111 112 if (sel == ARRAY_SIZE(multipliers))113 return -EINVAL;114 115 *slowsel = sel;116 117 return 0;118}119 120static int find_closest_slow(int target, int *slow_sel, int *fast_sel)121{122 static const int multipliers[] = {2, 3, 7, 15};123 int i, j;124 int val = 0;125 int window = FASTNG_MIN;126 127 for (i = 0; i < 8; i++) {128 for (j = 0; j < ARRAY_SIZE(multipliers); j++) {129 int slow;130 131 slow = window * multipliers[j];132 if (slow >= target && (!val || slow < val)) {133 val = slow;134 *fast_sel = i;135 *slow_sel = j;136 }137 }138 window <<= 1;139 }140 if (!val)141 return -EINVAL;142 143 return 0;144}145 146#define BD957X_WDG_TYPE_WINDOW BIT(5)147#define BD957X_WDG_TYPE_SLOW 0148#define BD957X_WDG_TYPE_MASK BIT(5)149#define BD957X_WDG_NG_RATIO_MASK 0x18150#define BD957X_WDG_FASTNG_MASK 0x7151 152static int bd957x_set_wdt_mode(struct bd9576_wdt_priv *priv, int hw_margin,153 int hw_margin_min)154{155 int ret, fastng, slowng, type, reg, mask;156 struct device *dev = priv->dev;157 158 /* convert to 100uS */159 hw_margin *= 10;160 hw_margin_min *= 10;161 if (hw_margin_min) {162 int min;163 164 type = BD957X_WDG_TYPE_WINDOW;165 dev_dbg(dev, "Setting type WINDOW 0x%x\n", type);166 ret = find_closest_fast(hw_margin_min, &fastng, &min);167 if (ret) {168 dev_err(dev, "bad WDT window for fast timeout\n");169 return ret;170 }171 172 ret = find_closest_slow_by_fast(min, hw_margin, &slowng);173 if (ret) {174 dev_err(dev, "bad WDT window\n");175 return ret;176 }177 178 } else {179 type = BD957X_WDG_TYPE_SLOW;180 dev_dbg(dev, "Setting type SLOW 0x%x\n", type);181 ret = find_closest_slow(hw_margin, &slowng, &fastng);182 if (ret) {183 dev_err(dev, "bad WDT window\n");184 return ret;185 }186 }187 188 slowng <<= ffs(BD957X_WDG_NG_RATIO_MASK) - 1;189 reg = type | slowng | fastng;190 mask = BD957X_WDG_TYPE_MASK | BD957X_WDG_NG_RATIO_MASK |191 BD957X_WDG_FASTNG_MASK;192 ret = regmap_update_bits(priv->regmap, BD957X_REG_WDT_CONF,193 mask, reg);194 195 return ret;196}197 198static int bd9576_wdt_probe(struct platform_device *pdev)199{200 struct device *dev = &pdev->dev;201 struct bd9576_wdt_priv *priv;202 u32 hw_margin[2];203 u32 hw_margin_max = BD957X_WDT_DEFAULT_MARGIN, hw_margin_min = 0;204 int count;205 int ret;206 207 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);208 if (!priv)209 return -ENOMEM;210 211 platform_set_drvdata(pdev, priv);212 213 priv->dev = dev;214 priv->regmap = dev_get_regmap(dev->parent, NULL);215 if (!priv->regmap) {216 dev_err(dev, "No regmap found\n");217 return -ENODEV;218 }219 220 priv->gpiod_en = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),221 "rohm,watchdog-enable",222 GPIOD_OUT_LOW,223 "watchdog-enable");224 if (IS_ERR(priv->gpiod_en))225 return dev_err_probe(dev, PTR_ERR(priv->gpiod_en),226 "getting watchdog-enable GPIO failed\n");227 228 priv->gpiod_ping = devm_fwnode_gpiod_get(dev, dev_fwnode(dev->parent),229 "rohm,watchdog-ping",230 GPIOD_OUT_LOW,231 "watchdog-ping");232 if (IS_ERR(priv->gpiod_ping))233 return dev_err_probe(dev, PTR_ERR(priv->gpiod_ping),234 "getting watchdog-ping GPIO failed\n");235 236 count = device_property_count_u32(dev->parent, "rohm,hw-timeout-ms");237 if (count < 0 && count != -EINVAL)238 return count;239 240 if (count > 0) {241 if (count > ARRAY_SIZE(hw_margin))242 return -EINVAL;243 244 ret = device_property_read_u32_array(dev->parent,245 "rohm,hw-timeout-ms",246 hw_margin, count);247 if (ret < 0)248 return ret;249 250 if (count == 1)251 hw_margin_max = hw_margin[0];252 253 if (count == 2) {254 hw_margin_max = hw_margin[1];255 hw_margin_min = hw_margin[0];256 }257 }258 259 ret = bd957x_set_wdt_mode(priv, hw_margin_max, hw_margin_min);260 if (ret)261 return ret;262 263 watchdog_set_drvdata(&priv->wdd, priv);264 265 priv->wdd.info = &bd957x_wdt_ident;266 priv->wdd.ops = &bd957x_wdt_ops;267 priv->wdd.min_hw_heartbeat_ms = hw_margin_min;268 priv->wdd.max_hw_heartbeat_ms = hw_margin_max;269 priv->wdd.parent = dev;270 priv->wdd.timeout = WATCHDOG_TIMEOUT;271 272 watchdog_init_timeout(&priv->wdd, 0, dev);273 watchdog_set_nowayout(&priv->wdd, nowayout);274 275 watchdog_stop_on_reboot(&priv->wdd);276 277 return devm_watchdog_register_device(dev, &priv->wdd);278}279 280static struct platform_driver bd9576_wdt_driver = {281 .driver = {282 .name = "bd9576-wdt",283 },284 .probe = bd9576_wdt_probe,285};286 287module_platform_driver(bd9576_wdt_driver);288 289MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");290MODULE_DESCRIPTION("ROHM BD9576/BD9573 Watchdog driver");291MODULE_LICENSE("GPL");292MODULE_ALIAS("platform:bd9576-wdt");293