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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * sl28cpld watchdog driver4 *5 * Copyright 2020 Kontron Europe GmbH6 */7 8#include <linux/kernel.h>9#include <linux/mod_devicetable.h>10#include <linux/module.h>11#include <linux/platform_device.h>12#include <linux/property.h>13#include <linux/regmap.h>14#include <linux/watchdog.h>15 16/*17 * Watchdog timer block registers.18 */19#define WDT_CTRL 0x0020#define WDT_CTRL_EN BIT(0)21#define WDT_CTRL_LOCK BIT(2)22#define WDT_CTRL_ASSERT_SYS_RESET BIT(6)23#define WDT_CTRL_ASSERT_WDT_TIMEOUT BIT(7)24#define WDT_TIMEOUT 0x0125#define WDT_KICK 0x0226#define WDT_KICK_VALUE 0x6b27#define WDT_COUNT 0x0328 29#define WDT_DEFAULT_TIMEOUT 1030 31static bool nowayout = WATCHDOG_NOWAYOUT;32module_param(nowayout, bool, 0);33MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="34 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");35 36static int timeout;37module_param(timeout, int, 0);38MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");39 40struct sl28cpld_wdt {41 struct watchdog_device wdd;42 struct regmap *regmap;43 u32 offset;44 bool assert_wdt_timeout;45};46 47static int sl28cpld_wdt_ping(struct watchdog_device *wdd)48{49 struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);50 51 return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,52 WDT_KICK_VALUE);53}54 55static int sl28cpld_wdt_start(struct watchdog_device *wdd)56{57 struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);58 unsigned int val;59 60 val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;61 if (wdt->assert_wdt_timeout)62 val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;63 if (nowayout)64 val |= WDT_CTRL_LOCK;65 66 return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,67 val, val);68}69 70static int sl28cpld_wdt_stop(struct watchdog_device *wdd)71{72 struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);73 74 return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,75 WDT_CTRL_EN, 0);76}77 78static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)79{80 struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);81 unsigned int val;82 int ret;83 84 ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);85 if (ret)86 return 0;87 88 return val;89}90 91static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,92 unsigned int timeout)93{94 struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);95 int ret;96 97 ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);98 if (ret)99 return ret;100 101 wdd->timeout = timeout;102 103 return 0;104}105 106static const struct watchdog_info sl28cpld_wdt_info = {107 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,108 .identity = "sl28cpld watchdog",109};110 111static const struct watchdog_ops sl28cpld_wdt_ops = {112 .owner = THIS_MODULE,113 .start = sl28cpld_wdt_start,114 .stop = sl28cpld_wdt_stop,115 .ping = sl28cpld_wdt_ping,116 .set_timeout = sl28cpld_wdt_set_timeout,117 .get_timeleft = sl28cpld_wdt_get_timeleft,118};119 120static int sl28cpld_wdt_probe(struct platform_device *pdev)121{122 struct watchdog_device *wdd;123 struct sl28cpld_wdt *wdt;124 unsigned int status;125 unsigned int val;126 int ret;127 128 if (!pdev->dev.parent)129 return -ENODEV;130 131 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);132 if (!wdt)133 return -ENOMEM;134 135 wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);136 if (!wdt->regmap)137 return -ENODEV;138 139 ret = device_property_read_u32(&pdev->dev, "reg", &wdt->offset);140 if (ret)141 return -EINVAL;142 143 wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,144 "kontron,assert-wdt-timeout-pin");145 146 /* initialize struct watchdog_device */147 wdd = &wdt->wdd;148 wdd->parent = &pdev->dev;149 wdd->info = &sl28cpld_wdt_info;150 wdd->ops = &sl28cpld_wdt_ops;151 wdd->min_timeout = 1;152 wdd->max_timeout = 255;153 154 watchdog_set_drvdata(wdd, wdt);155 watchdog_stop_on_reboot(wdd);156 157 /*158 * Read the status early, in case of an error, we haven't modified the159 * hardware.160 */161 ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);162 if (ret)163 return ret;164 165 /*166 * Initial timeout value, may be overwritten by device tree or module167 * parameter in watchdog_init_timeout().168 *169 * Reading a zero here means that either the hardware has a default170 * value of zero (which is very unlikely and definitely a hardware171 * bug) or the bootloader set it to zero. In any case, we handle172 * this case gracefully and set out own timeout.173 */174 ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);175 if (ret)176 return ret;177 178 if (val)179 wdd->timeout = val;180 else181 wdd->timeout = WDT_DEFAULT_TIMEOUT;182 183 watchdog_init_timeout(wdd, timeout, &pdev->dev);184 sl28cpld_wdt_set_timeout(wdd, wdd->timeout);185 186 /* if the watchdog is locked, we set nowayout */187 if (status & WDT_CTRL_LOCK)188 nowayout = true;189 watchdog_set_nowayout(wdd, nowayout);190 191 /*192 * If watchdog is already running, keep it enabled, but make193 * sure its mode is set correctly.194 */195 if (status & WDT_CTRL_EN) {196 sl28cpld_wdt_start(wdd);197 set_bit(WDOG_HW_RUNNING, &wdd->status);198 }199 200 ret = devm_watchdog_register_device(&pdev->dev, wdd);201 if (ret < 0) {202 dev_err(&pdev->dev, "failed to register watchdog device\n");203 return ret;204 }205 206 dev_info(&pdev->dev, "initial timeout %d sec%s\n",207 wdd->timeout, nowayout ? ", nowayout" : "");208 209 return 0;210}211 212static const struct of_device_id sl28cpld_wdt_of_match[] = {213 { .compatible = "kontron,sl28cpld-wdt" },214 {}215};216MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);217 218static struct platform_driver sl28cpld_wdt_driver = {219 .probe = sl28cpld_wdt_probe,220 .driver = {221 .name = "sl28cpld-wdt",222 .of_match_table = sl28cpld_wdt_of_match,223 },224};225module_platform_driver(sl28cpld_wdt_driver);226 227MODULE_DESCRIPTION("sl28cpld Watchdog Driver");228MODULE_AUTHOR("Michael Walle <michael@walle.cc>");229MODULE_LICENSE("GPL");230