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    Subject[PATCH v4 04/11] watchdog: add support for sl28cpld watchdog
    Date
    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>
    ---
    drivers/watchdog/Kconfig | 11 ++
    drivers/watchdog/Makefile | 1 +
    drivers/watchdog/sl28cpld_wdt.c | 231 ++++++++++++++++++++++++++++++++
    3 files changed, 243 insertions(+)
    create mode 100644 drivers/watchdog/sl28cpld_wdt.c

    diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
    index 55b910c453da..2c7b0f10151e 100644
    --- a/drivers/watchdog/Kconfig
    +++ b/drivers/watchdog/Kconfig
    @@ -340,6 +340,17 @@ config MLX_WDT
    To compile this driver as a module, choose M here: the
    module will be called mlx-wdt.

    +config SL28CPLD_WATCHDOG
    + tristate "Kontron sl28 watchdog"
    + depends on MFD_SL28CPLD
    + select WATCHDOG_CORE
    + help
    + Say Y here to include support for the watchdog timer
    + on the Kontron sl28 CPLD.
    +
    + To compile this driver as a module, choose M here: the
    + module will be called sl28cpld_wdt.
    +
    # ALPHA Architecture

    # ARM Architecture
    diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
    index 97bed1d3d97c..aa6e41126901 100644
    --- a/drivers/watchdog/Makefile
    +++ b/drivers/watchdog/Makefile
    @@ -225,3 +225,4 @@ obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
    obj-$(CONFIG_MENZ069_WATCHDOG) += menz69_wdt.o
    obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
    obj-$(CONFIG_STPMIC1_WATCHDOG) += stpmic1_wdt.o
    +obj-$(CONFIG_SL28CPLD_WATCHDOG) += sl28cpld_wdt.o
    diff --git a/drivers/watchdog/sl28cpld_wdt.c b/drivers/watchdog/sl28cpld_wdt.c
    new file mode 100644
    index 000000000000..6c9518dc454a
    --- /dev/null
    +++ b/drivers/watchdog/sl28cpld_wdt.c
    @@ -0,0 +1,231 @@
    +// SPDX-License-Identifier: GPL-2.0-only
    +/*
    + * sl28cpld watchdog driver.
    + *
    + * Copyright 2019 Kontron Europe GmbH
    + */
    +
    +#include <linux/kernel.h>
    +#include <linux/module.h>
    +#include <linux/of_device.h>
    +#include <linux/platform_device.h>
    +#include <linux/regmap.h>
    +#include <linux/watchdog.h>
    +
    +/*
    + * Watchdog timer block registers.
    + */
    +#define WDT_CTRL 0x00
    +#define WDT_CTRL_EN BIT(0)
    +#define WDT_CTRL_LOCK BIT(2)
    +#define WDT_CTRL_ASSERT_SYS_RESET BIT(6)
    +#define WDT_CTRL_ASSERT_WDT_TIMEOUT BIT(7)
    +#define WDT_TIMEOUT 0x01
    +#define WDT_KICK 0x02
    +#define WDT_KICK_VALUE 0x6b
    +#define WDT_COUNT 0x03
    +
    +#define WDT_DEFAULT_TIMEOUT 10
    +
    +static bool nowayout = WATCHDOG_NOWAYOUT;
    +module_param(nowayout, bool, 0);
    +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
    + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
    +
    +static int timeout;
    +module_param(timeout, int, 0);
    +MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
    +
    +struct sl28cpld_wdt {
    + struct watchdog_device wdd;
    + struct regmap *regmap;
    + u32 offset;
    + bool assert_wdt_timeout;
    +};
    +
    +static int sl28cpld_wdt_ping(struct watchdog_device *wdd)
    +{
    + struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
    +
    + return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,
    + WDT_KICK_VALUE);
    +}
    +
    +static int sl28cpld_wdt_start(struct watchdog_device *wdd)
    +{
    + struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
    + unsigned int val;
    +
    + val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;
    + if (wdt->assert_wdt_timeout)
    + val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;
    + if (nowayout)
    + val |= WDT_CTRL_LOCK;
    +
    + return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
    + val, val);
    +}
    +
    +static int sl28cpld_wdt_stop(struct watchdog_device *wdd)
    +{
    + struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
    +
    + return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
    + WDT_CTRL_EN, 0);
    +}
    +
    +static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)
    +{
    + struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
    + unsigned int val;
    + int ret;
    +
    + ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);
    +
    + return (ret < 0) ? 0 : val;
    +}
    +
    +static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,
    + unsigned int timeout)
    +{
    + struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
    + int ret;
    +
    + ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);
    + if (!ret)
    + wdd->timeout = timeout;
    +
    + return ret;
    +}
    +
    +static const struct watchdog_info sl28cpld_wdt_info = {
    + .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
    + .identity = "sl28cpld watchdog",
    +};
    +
    +static struct watchdog_ops sl28cpld_wdt_ops = {
    + .owner = THIS_MODULE,
    + .start = sl28cpld_wdt_start,
    + .stop = sl28cpld_wdt_stop,
    + .ping = sl28cpld_wdt_ping,
    + .set_timeout = sl28cpld_wdt_set_timeout,
    + .get_timeleft = sl28cpld_wdt_get_timeleft,
    +};
    +
    +static int sl28cpld_wdt_probe(struct platform_device *pdev)
    +{
    + struct watchdog_device *wdd;
    + struct sl28cpld_wdt *wdt;
    + unsigned int status;
    + unsigned int val;
    + int ret;
    +
    + if (!pdev->dev.parent)
    + return -ENODEV;
    +
    + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
    + if (!wdt)
    + return -ENOMEM;
    +
    + wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);
    + if (!wdt->regmap)
    + return -ENODEV;
    +
    + ret = device_property_read_u32(&pdev->dev, "reg", &wdt->offset);
    + if (ret)
    + return -EINVAL;
    +
    + wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,
    + "kontron,assert-wdt-timeout-pin");
    +
    + /* initialize struct watchdog_device */
    + wdd = &wdt->wdd;
    + wdd->parent = &pdev->dev;
    + wdd->info = &sl28cpld_wdt_info;
    + wdd->ops = &sl28cpld_wdt_ops;
    + wdd->min_timeout = 1;
    + wdd->max_timeout = 255;
    +
    + watchdog_set_drvdata(wdd, wdt);
    + watchdog_stop_on_reboot(wdd);
    +
    + /*
    + * Read the status early, in case of an error, we haven't modified the
    + * hardware.
    + */
    + ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);
    + if (ret < 0)
    + return ret;
    +
    + /*
    + * Initial timeout value, may be overwritten by device tree or module
    + * parmeter in watchdog_init_timeout().
    + *
    + * Reading a zero here means that either the hardware has a default
    + * value of zero (which is very unlikely and definitely a hardware
    + * bug) or the bootloader set it to zero. In any case, we handle
    + * this case gracefully and set out own timeout.
    + */
    + ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);
    + if (ret < 0)
    + return ret;
    +
    + if (val)
    + wdd->timeout = val;
    + else
    + wdd->timeout = WDT_DEFAULT_TIMEOUT;
    +
    + watchdog_init_timeout(wdd, timeout, &pdev->dev);
    + sl28cpld_wdt_set_timeout(wdd, wdd->timeout);
    +
    + /* if the watchdog is locked, we set nowayout */
    + if (status & WDT_CTRL_LOCK)
    + nowayout = true;
    + watchdog_set_nowayout(wdd, nowayout);
    +
    + /*
    + * If watchdog is already running, keep it enabled, but make
    + * sure its mode is set correctly.
    + */
    + if (status & WDT_CTRL_EN) {
    + sl28cpld_wdt_start(wdd);
    + set_bit(WDOG_HW_RUNNING, &wdd->status);
    + }
    +
    + ret = devm_watchdog_register_device(&pdev->dev, wdd);
    + if (ret < 0) {
    + dev_err(&pdev->dev, "failed to register watchdog device\n");
    + return ret;
    + }
    +
    + dev_info(&pdev->dev, "initial timeout %d sec%s\n",
    + wdd->timeout, nowayout ? ", nowayout" : "");
    +
    + return 0;
    +}
    +
    +static const struct of_device_id sl28cpld_wdt_of_match[] = {
    + { .compatible = "kontron,sl28cpld-wdt" },
    + {},
    +};
    +MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);
    +
    +static const struct platform_device_id sl28cpld_wdt_id_table[] = {
    + { "sl28cpld-wdt" },
    + {},
    +};
    +MODULE_DEVICE_TABLE(platform, sl28cpld_wdt_id_table);
    +
    +static struct platform_driver sl28cpld_wdt_driver = {
    + .probe = sl28cpld_wdt_probe,
    + .id_table = sl28cpld_wdt_id_table,
    + .driver = {
    + .name = KBUILD_MODNAME,
    + .of_match_table = sl28cpld_wdt_of_match,
    + },
    +};
    +module_platform_driver(sl28cpld_wdt_driver);
    +
    +MODULE_DESCRIPTION("sl28cpld Watchdog Driver");
    +MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
    +MODULE_LICENSE("GPL");
    --
    2.20.1
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      Last update: 2020-06-04 23:13    [W:3.265 / U:1.556 seconds]
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