[PATCH v4 2/2] watchdog: Add Toshiba Visconti watchdog driver

[Guenter Roeck]

On Mon, Sep 21, 2020 at 06:12:35PM +0900, Nobuhiro Iwamatsu wrote:
> Add the watchdog driver for Toshiba Visconti series.
> 
> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu at toshiba.co.jp>
> Reviewed-by: Punit Agrawal <punit1.agrawal at toshiba.co.jp>
> ---
>  drivers/watchdog/Kconfig        |   8 ++
>  drivers/watchdog/Makefile       |   1 +
>  drivers/watchdog/visconti_wdt.c | 189 ++++++++++++++++++++++++++++++++
>  3 files changed, 198 insertions(+)
>  create mode 100644 drivers/watchdog/visconti_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index ab7aad5a1e69..0cb078ce5e9d 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1004,6 +1004,14 @@ config PM8916_WATCHDOG
>  	  Say Y here to include support watchdog timer embedded into the
>  	  pm8916 module.
>  
> +config VISCONTI_WATCHDOG
> +	tristate "Toshiba Visconti series watchdog support"
> +	depends on ARCH_VISCONTI || COMPILE_TEST
> +	select WATCHDOG_CORE
> +	help
> +	  Say Y here to include support for the watchdog timer in Toshiba
> +	  Visconti SoCs.
> +
>  # X86 (i386 + ia64 + x86_64) Architecture
>  
>  config ACQUIRE_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 97bed1d3d97c..a7747e76fd29 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -95,6 +95,7 @@ obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o
>  obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
>  obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
>  obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
> +obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
>  
>  # X86 (i386 + ia64 + x86_64) Architecture
>  obj-$(CONFIG_ACQUIRE_WDT) += acquirewdt.o
> diff --git a/drivers/watchdog/visconti_wdt.c b/drivers/watchdog/visconti_wdt.c
> new file mode 100644
> index 000000000000..9448eaaa51b6
> --- /dev/null
> +++ b/drivers/watchdog/visconti_wdt.c
> @@ -0,0 +1,189 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2020 TOSHIBA CORPORATION
> + * Copyright (c) 2020 Toshiba Electronic Devices & Storage Corporation
> + * Copyright (c) 2020 Nobuhiro Iwamatsu <nobuhiro1.iwamatsu at toshiba.co.jp>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/watchdog.h>
> +
> +#define WDT_CNT			0x00
> +#define WDT_MIN			0x04
> +#define WDT_MAX			0x08
> +#define WDT_CTL			0x0c
> +#define WDT_CMD			0x10
> +#define WDT_CMD_CLEAR		0x4352
> +#define WDT_CMD_START_STOP	0x5354
> +#define WDT_DIV			0x30
> +
> +#define VISCONTI_WDT_FREQ	2000000 /* 2MHz */
> +#define WDT_DEFAULT_TIMEOUT	10U /* in seconds */
> +
> +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)")");
> +
> +struct visconti_wdt_priv {
> +	struct watchdog_device wdev;
> +	void __iomem *base;
> +	u32 div;
> +};
> +
> +static int visconti_wdt_start(struct watchdog_device *wdev)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
> +
> +	writel(priv->div, priv->base + WDT_DIV);
> +	writel(0, priv->base + WDT_MIN);
> +	writel(timeout, priv->base + WDT_MAX);
> +	writel(0, priv->base + WDT_CTL);
> +	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
> +
> +	return 0;
> +}
> +
> +static int visconti_wdt_stop(struct watchdog_device *wdev)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	writel(1, priv->base + WDT_CTL);
> +	writel(WDT_CMD_START_STOP, priv->base + WDT_CMD);
> +
> +	return 0;
> +}
> +
> +static int visconti_wdt_ping(struct watchdog_device *wdd)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdd);
> +
> +	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
> +
> +	return 0;
> +}
> +
> +static unsigned int visconti_wdt_get_timeleft(struct watchdog_device *wdev)
> +{
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +	u32 timeout = wdev->timeout * VISCONTI_WDT_FREQ;
> +	u32 cnt = readl(priv->base + WDT_CNT);
> +
> +	if (timeout <= cnt)
> +		return 0;
> +	timeout -= cnt;
> +
> +	return timeout / VISCONTI_WDT_FREQ;
> +}
> +
> +static int visconti_wdt_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
> +{
> +	u32 val;
> +	struct visconti_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	wdev->timeout = timeout;
> +	val = wdev->timeout * VISCONTI_WDT_FREQ;
> +
> +	/* Clear counter before setting timeout because WDT expires */
> +	writel(WDT_CMD_CLEAR, priv->base + WDT_CMD);
> +	writel(val, priv->base + WDT_MAX);
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info visconti_wdt_info = {
> +	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> +	.identity = "Visconti Watchdog",
> +};
> +
> +static const struct watchdog_ops visconti_wdt_ops = {
> +	.owner		= THIS_MODULE,
> +	.start		= visconti_wdt_start,
> +	.stop		= visconti_wdt_stop,
> +	.ping		= visconti_wdt_ping,
> +	.get_timeleft	= visconti_wdt_get_timeleft,
> +	.set_timeout	= visconti_wdt_set_timeout,
> +};
> +
> +static int visconti_wdt_probe(struct platform_device *pdev)
> +{
> +	struct watchdog_device *wdev;
> +	struct visconti_wdt_priv *priv;
> +	struct device *dev = &pdev->dev;
> +	struct clk *clk;
> +	int ret;
> +	unsigned long clk_freq;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(priv->base))
> +		return PTR_ERR(priv->base);
> +
> +	clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(clk))
> +		return dev_err_probe(dev, PTR_ERR(clk), "Could not get clock\n");
> +
> +	ret = clk_prepare_enable(clk);
> +	if (ret) {
> +		dev_err(dev, "Could not enable clock\n");
> +		return ret;
> +	}

There is no clk_disable_unprepare() when the driver is removed, or when
devm_watchdog_register_device() fails. For situations like this I suggest
to handle cleanup with devm_add_action_or_reset(), which would also
simplify error handling. There are lots of examples in other watchdog
drivers.

Guenter

> +
> +	clk_freq = clk_get_rate(clk);
> +	if (!clk_freq) {
> +		clk_disable_unprepare(clk);
> +		dev_err(dev, "Could not get clock rate\n");
> +		return -EINVAL;
> +	}
> +
> +	priv->div = clk_freq / VISCONTI_WDT_FREQ;
> +
> +	/* Initialize struct watchdog_device. */
> +	wdev = &priv->wdev;
> +	wdev->info = &visconti_wdt_info;
> +	wdev->ops = &visconti_wdt_ops;
> +	wdev->parent = dev;
> +	wdev->min_timeout = 1;
> +	wdev->max_timeout = 0xffffffff / VISCONTI_WDT_FREQ;
> +	wdev->timeout = min(wdev->max_timeout, WDT_DEFAULT_TIMEOUT);
> +
> +	watchdog_set_drvdata(wdev, priv);
> +	watchdog_set_nowayout(wdev, nowayout);
> +	watchdog_stop_on_unregister(wdev);
> +
> +	/* This overrides the default timeout only if DT configuration was found */
> +	ret = watchdog_init_timeout(wdev, 0, dev);
> +	if (ret)
> +		dev_warn(dev, "Specified timeout value invalid, using default\n");
> +
> +	return devm_watchdog_register_device(dev, wdev);
> +}
> +
> +static const struct of_device_id visconti_wdt_of_match[] = {
> +	{ .compatible = "toshiba,visconti-wdt", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, visconti_wdt_of_match);
> +
> +static struct platform_driver visconti_wdt_driver = {
> +	.driver = {
> +			.name = "visconti_wdt",
> +			.of_match_table = visconti_wdt_of_match,
> +		},
> +	.probe = visconti_wdt_probe,
> +};
> +module_platform_driver(visconti_wdt_driver);
> +
> +MODULE_DESCRIPTION("TOSHIBA Visconti Watchdog Driver");
> +MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu at toshiba.co.jp");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.27.0
>