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Add support for the watchdog of the sl28cpld board management controller. This is part of a multi-function device driver. Signed-off-by: Michael Walle <michael@walle.cc> Acked-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Lee Jones <lee.jones@linaro.org>
230 lines
5.5 KiB
C
230 lines
5.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* sl28cpld watchdog driver
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*
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* Copyright 2020 Kontron Europe GmbH
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*/
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#include <linux/kernel.h>
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#include <linux/mod_devicetable.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/regmap.h>
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#include <linux/watchdog.h>
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/*
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* Watchdog timer block registers.
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*/
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#define WDT_CTRL 0x00
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#define WDT_CTRL_EN BIT(0)
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#define WDT_CTRL_LOCK BIT(2)
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#define WDT_CTRL_ASSERT_SYS_RESET BIT(6)
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#define WDT_CTRL_ASSERT_WDT_TIMEOUT BIT(7)
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#define WDT_TIMEOUT 0x01
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#define WDT_KICK 0x02
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#define WDT_KICK_VALUE 0x6b
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#define WDT_COUNT 0x03
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#define WDT_DEFAULT_TIMEOUT 10
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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static int timeout;
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module_param(timeout, int, 0);
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MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
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struct sl28cpld_wdt {
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struct watchdog_device wdd;
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struct regmap *regmap;
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u32 offset;
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bool assert_wdt_timeout;
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};
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static int sl28cpld_wdt_ping(struct watchdog_device *wdd)
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{
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struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
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return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,
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WDT_KICK_VALUE);
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}
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static int sl28cpld_wdt_start(struct watchdog_device *wdd)
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{
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struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
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unsigned int val;
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val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;
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if (wdt->assert_wdt_timeout)
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val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;
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if (nowayout)
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val |= WDT_CTRL_LOCK;
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return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
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val, val);
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}
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static int sl28cpld_wdt_stop(struct watchdog_device *wdd)
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{
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struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
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return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
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WDT_CTRL_EN, 0);
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}
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static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)
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{
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struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
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unsigned int val;
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int ret;
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ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);
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if (ret)
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return 0;
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return val;
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}
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static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,
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unsigned int timeout)
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{
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struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
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int ret;
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ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);
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if (ret)
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return ret;
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wdd->timeout = timeout;
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return 0;
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}
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static const struct watchdog_info sl28cpld_wdt_info = {
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.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
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.identity = "sl28cpld watchdog",
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};
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static struct watchdog_ops sl28cpld_wdt_ops = {
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.owner = THIS_MODULE,
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.start = sl28cpld_wdt_start,
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.stop = sl28cpld_wdt_stop,
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.ping = sl28cpld_wdt_ping,
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.set_timeout = sl28cpld_wdt_set_timeout,
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.get_timeleft = sl28cpld_wdt_get_timeleft,
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};
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static int sl28cpld_wdt_probe(struct platform_device *pdev)
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{
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struct watchdog_device *wdd;
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struct sl28cpld_wdt *wdt;
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unsigned int status;
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unsigned int val;
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int ret;
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if (!pdev->dev.parent)
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return -ENODEV;
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wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
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if (!wdt)
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return -ENOMEM;
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wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);
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if (!wdt->regmap)
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return -ENODEV;
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ret = device_property_read_u32(&pdev->dev, "reg", &wdt->offset);
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if (ret)
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return -EINVAL;
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wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,
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"kontron,assert-wdt-timeout-pin");
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/* initialize struct watchdog_device */
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wdd = &wdt->wdd;
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wdd->parent = &pdev->dev;
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wdd->info = &sl28cpld_wdt_info;
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wdd->ops = &sl28cpld_wdt_ops;
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wdd->min_timeout = 1;
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wdd->max_timeout = 255;
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watchdog_set_drvdata(wdd, wdt);
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watchdog_stop_on_reboot(wdd);
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/*
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* Read the status early, in case of an error, we haven't modified the
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* hardware.
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*/
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ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);
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if (ret)
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return ret;
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/*
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* Initial timeout value, may be overwritten by device tree or module
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* parmeter in watchdog_init_timeout().
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*
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* Reading a zero here means that either the hardware has a default
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* value of zero (which is very unlikely and definitely a hardware
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* bug) or the bootloader set it to zero. In any case, we handle
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* this case gracefully and set out own timeout.
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*/
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ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);
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if (ret)
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return ret;
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if (val)
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wdd->timeout = val;
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else
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wdd->timeout = WDT_DEFAULT_TIMEOUT;
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watchdog_init_timeout(wdd, timeout, &pdev->dev);
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sl28cpld_wdt_set_timeout(wdd, wdd->timeout);
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/* if the watchdog is locked, we set nowayout */
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if (status & WDT_CTRL_LOCK)
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nowayout = true;
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watchdog_set_nowayout(wdd, nowayout);
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/*
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* If watchdog is already running, keep it enabled, but make
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* sure its mode is set correctly.
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*/
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if (status & WDT_CTRL_EN) {
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sl28cpld_wdt_start(wdd);
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set_bit(WDOG_HW_RUNNING, &wdd->status);
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}
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ret = devm_watchdog_register_device(&pdev->dev, wdd);
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if (ret < 0) {
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dev_err(&pdev->dev, "failed to register watchdog device\n");
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return ret;
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}
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dev_info(&pdev->dev, "initial timeout %d sec%s\n",
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wdd->timeout, nowayout ? ", nowayout" : "");
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return 0;
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}
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static const struct of_device_id sl28cpld_wdt_of_match[] = {
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{ .compatible = "kontron,sl28cpld-wdt" },
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{}
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};
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MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);
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static struct platform_driver sl28cpld_wdt_driver = {
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.probe = sl28cpld_wdt_probe,
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.driver = {
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.name = "sl28cpld-wdt",
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.of_match_table = sl28cpld_wdt_of_match,
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},
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};
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module_platform_driver(sl28cpld_wdt_driver);
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MODULE_DESCRIPTION("sl28cpld Watchdog Driver");
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MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
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MODULE_LICENSE("GPL");
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