Re: [RFC 5/5] watchdog: sh_mobile: add driver

[Simon Horman <horms@verge.net.au>]

On Sun, Feb 01, 2015 at 03:47:54PM +0100, Wolfram Sang wrote:
> From: Wolfram Sang <wsa+renesas@sang-engineering.com>
> 
> Add basic support for an RCLK watchdog found in at least all RCar-Gen2
> based SoCs from Renesas. It probably works even for the "Secure
> watchdog" of some of those SoCs according to the specs I have. Setting a
> timeout value is not implemented yet, I didn't need it. A restart
> handler is in place, though.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Hi Wolfram,

I don't have any particular comments on the code at this time but
as it adds a new binding it seems that it will need to be reviewed
by the DT people.

And with regards to merging, its not clear to me who if anyone
is the maintainer of watchdog drivers. But perhaps there is some
appropriate forum for review from that point of view. And perhaps
this is a candidate to submit directly to Linus rather than going
through my tree and in turn the ARM SoC tree.

> ---
>  drivers/watchdog/Kconfig         |   8 ++
>  drivers/watchdog/Makefile        |   1 +
>  drivers/watchdog/sh_mobile_wdt.c | 182 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 191 insertions(+)
>  create mode 100644 drivers/watchdog/sh_mobile_wdt.c
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 08f41add1461..70307c972b0d 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -505,6 +505,14 @@ config MESON_WATCHDOG
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called meson_wdt.
>  
> +config SH_MOBILE_WDT
> +	tristate "SH Mobile Watchdog"
> +	depends on ARCH_SHMOBILE || COMPILE_TEST
> +	select WATCHDOG_CORE
> +	help
> +	  This driver adds watchdog support for the integrated watchdog in the
> +	  Renesas SH Mobile SoCs.
> +
>  # AVR32 Architecture
>  
>  config AT32AP700X_WDT
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index c569ec8f8a76..796686e4c988 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -63,6 +63,7 @@ obj-$(CONFIG_QCOM_WDT) += qcom-wdt.o
>  obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
>  obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
>  obj-$(CONFIG_MESON_WATCHDOG) += meson_wdt.o
> +obj-$(CONFIG_SH_MOBILE_WDT) += sh_mobile_wdt.o
>  
>  # AVR32 Architecture
>  obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
> diff --git a/drivers/watchdog/sh_mobile_wdt.c b/drivers/watchdog/sh_mobile_wdt.c
> new file mode 100644
> index 000000000000..35016c147f33
> --- /dev/null
> +++ b/drivers/watchdog/sh_mobile_wdt.c
> @@ -0,0 +1,182 @@
> +/*
> + * Watchdog driver for SH mobile based SoC
> + *
> + * Copyright (C) 2015 Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
> + * Copyright (C) 2015 Renesas Electronics Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +#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/reboot.h>
> +#include <linux/watchdog.h>
> +
> +#define RWTCNT		0
> +#define RWTCSRA		4
> +#define RWTCSRA_WOVF	BIT(4)
> +#define RWTCSRA_WRFLG	BIT(5)
> +#define RWTCSRA_TME	BIT(7)
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, S_IRUGO);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
> +				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +struct sh_wdt_priv {
> +	void __iomem *base;
> +	struct watchdog_device wdev;
> +	struct clk *clk;
> +	struct notifier_block restart_handler;
> +};
> +
> +static void sh_wdt_write(struct sh_wdt_priv *priv, u32 val, unsigned reg)
> +{
> +	if (reg = RWTCNT)
> +		val |= 0x5a5a0000;
> +	else
> +		val |= 0xa5a5a500;
> +
> +	writel_relaxed(val, priv->base + reg);
> +}
> +
> +static int sh_wdt_start(struct watchdog_device *wdev)
> +{
> +	struct sh_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	clk_prepare_enable(priv->clk);
> +
> +	sh_wdt_write(priv, 0, RWTCSRA);
> +	sh_wdt_write(priv, 0, RWTCNT);
> +
> +	while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
> +		cpu_relax();
> +
> +	sh_wdt_write(priv, RWTCSRA_TME, RWTCSRA);
> +
> +	return 0;
> +}
> +
> +static int sh_wdt_ping(struct watchdog_device *wdev)
> +{
> +	struct sh_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	sh_wdt_write(priv, 0, RWTCNT);
> +
> +	return 0;
> +}
> +
> +static int sh_wdt_stop(struct watchdog_device *wdev)
> +{
> +	struct sh_wdt_priv *priv = watchdog_get_drvdata(wdev);
> +
> +	sh_wdt_write(priv, 0, RWTCSRA);
> +	clk_disable_unprepare(priv->clk);
> +
> +	return 0;
> +}
> +
> +static const struct watchdog_info sh_wdt_ident = {
> +	.options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> +	.identity = "SH Mobile Watchdog",
> +};
> +
> +static const struct watchdog_ops sh_wdt_ops = {
> +	.owner = THIS_MODULE,
> +	.start = sh_wdt_start,
> +	.ping = sh_wdt_ping,
> +	.stop = sh_wdt_stop,
> +};
> +
> +static int sh_mobile_wdt_restart_handler(struct notifier_block *nb,
> +					 unsigned long mode, void *cmd)
> +{
> +	struct sh_wdt_priv *priv = container_of(nb, struct sh_wdt_priv,
> +						restart_handler);
> +
> +	sh_wdt_start(&priv->wdev);
> +	sh_wdt_write(priv, 0xfff0, RWTCNT);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int sh_wdt_probe(struct platform_device *pdev)
> +{
> +	struct sh_wdt_priv *priv;
> +	struct resource *res;
> +	u8 val;
> +	int ret;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	priv->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(priv->base))
> +		return PTR_ERR(priv->base);
> +
> +	priv->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(priv->clk))
> +		return PTR_ERR(priv->clk);
> +
> +	clk_prepare_enable(priv->clk);
> +	val = readb_relaxed(priv->base + RWTCSRA);
> +	clk_disable_unprepare(priv->clk);
> +
> +	priv->wdev.bootstatus = (val & RWTCSRA_WOVF) ? WDIOF_CARDRESET : 0;
> +	priv->wdev.info = &sh_wdt_ident,
> +	priv->wdev.ops = &sh_wdt_ops,
> +
> +	platform_set_drvdata(pdev, priv);
> +	watchdog_set_drvdata(&priv->wdev, priv);
> +	watchdog_set_nowayout(&priv->wdev, nowayout);
> +
> +	ret = watchdog_register_device(&priv->wdev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "cannot register watchdog device\n");
> +		return ret;
> +	}
> +
> +	priv->restart_handler.notifier_call = sh_mobile_wdt_restart_handler;
> +	priv->restart_handler.priority = 192;
> +	ret = register_restart_handler(&priv->restart_handler);
> +	if (ret)
> +		dev_warn(&pdev->dev, "Failed to register restart handler (err = %d)\n", ret);
> +
> +	return 0;
> +}
> +
> +static int sh_wdt_remove(struct platform_device *pdev)
> +{
> +	struct sh_wdt_priv *priv = platform_get_drvdata(pdev);
> +
> +	unregister_restart_handler(&priv->restart_handler);
> +	watchdog_unregister_device(&priv->wdev);
> +	return 0;
> +}
> +
> +static const struct of_device_id sh_mobile_wdt_ids[] = {
> +	{ .compatible = "renesas,rwdt-rcar", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, sh_mobile_wdt_ids);
> +
> +static struct platform_driver sh_wdt_driver = {
> +	.driver = {
> +		.name = "sh_mobile_wdt",
> +		.of_match_table = sh_mobile_wdt_ids,
> +	},
> +	.probe = sh_wdt_probe,
> +	.remove = sh_wdt_remove,
> +};
> +module_platform_driver(sh_wdt_driver);
> +
> +MODULE_DESCRIPTION("SH Mobile Watchdog Driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
> -- 
> 2.1.4
> 
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