linux-kernel - Re: [PATCH v6 2/2] watchdog: mtk_wdt: mt8183: Add reset controller

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Message-ID: <fe8b8b2aac6d92a1d7ffc32ea012db9898ab6857.camel@pengutronix.de>
Date:   Wed, 11 Dec 2019 17:44:55 +0100
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Jiaxin Yu <jiaxin.yu@...iatek.com>, yong.liang@...iatek.com,
        wim@...ux-watchdog.org, linux@...ck-us.net, matthias.bgg@...il.com,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org
Cc:     yingjoe.chen@...iatek.com, sboyd@...nel.org
Subject: Re: [PATCH v6 2/2] watchdog: mtk_wdt: mt8183: Add reset controller

Hi,

On Thu, 2019-12-12 at 00:22 +0800, Jiaxin Yu wrote:
> From: "yong.liang" <yong.liang@...iatek.com>
> 
> Add reset controller API in watchdog driver.
> Besides watchdog, MTK toprgu module alsa provide sub-system (eg, audio,
> camera, codec and connectivity) software reset functionality.

Do any of the listed sub-systems use the reset_control_reset()
functionality? Is there no delay requirement between assert and
deassert? Otherwise it would be safer not to implement the .reset()
operation at all.

> 
> Signed-off-by: yong.liang <yong.liang@...iatek.com>
> ---
>  drivers/watchdog/Kconfig   |   1 +
>  drivers/watchdog/mtk_wdt.c | 109 ++++++++++++++++++++++++++++++++++++-
>  2 files changed, 109 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 2e07caab9db2..629249fe5305 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -717,6 +717,7 @@ config MEDIATEK_WATCHDOG
>  	tristate "Mediatek SoCs watchdog support"
>  	depends on ARCH_MEDIATEK || COMPILE_TEST
>  	select WATCHDOG_CORE
> +	select RESET_CONTROLLER
>  	help
>  	  Say Y here to include support for the watchdog timer
>  	  in Mediatek SoCs.
> diff --git a/drivers/watchdog/mtk_wdt.c b/drivers/watchdog/mtk_wdt.c
> index 9c3d0033260d..667380031dfd 100644
> --- a/drivers/watchdog/mtk_wdt.c
> +++ b/drivers/watchdog/mtk_wdt.c
> @@ -9,6 +9,9 @@
>   * Based on sunxi_wdt.c
>   */
>  
> +#include <dt-bindings/reset-controller/mt2712-resets.h>
> +#include <dt-bindings/reset-controller/mt8183-resets.h>
> +#include <linux/delay.h>
>  #include <linux/err.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> @@ -16,10 +19,12 @@
>  #include <linux/module.h>
>  #include <linux/moduleparam.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
>  #include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +#include <linux/slab.h>

What is this required for?

>  #include <linux/types.h>
>  #include <linux/watchdog.h>
> -#include <linux/delay.h>
>
>  #define WDT_MAX_TIMEOUT		31
>  #define WDT_MIN_TIMEOUT		1
> @@ -44,6 +49,9 @@
>  #define WDT_SWRST		0x14
>  #define WDT_SWRST_KEY		0x1209
>  
> +#define WDT_SWSYSRST		0x18U
> +#define WDT_SWSYS_RST_KEY	0x88000000
> +
>  #define DRV_NAME		"mtk-wdt"
>  #define DRV_VERSION		"1.0"
>  
> @@ -53,8 +61,97 @@ static unsigned int timeout;
>  struct mtk_wdt_dev {
>  	struct watchdog_device wdt_dev;
>  	void __iomem *wdt_base;
> +	spinlock_t lock; /* protects WDT_SWSYSRST reg */
> +	struct reset_controller_dev rcdev;
> +};
> +
> +struct mtk_wdt_data {
> +	int infracfg_sw_rst_num;

This is not used at all, better remove it.

> +	int toprgu_sw_rst_num;
> +};
> +
> +static const struct mtk_wdt_data mt2712_data = {
> +	.toprgu_sw_rst_num = MT2712_TOPRGU_SW_RST_NUM,
> +};
> +
> +static const struct mtk_wdt_data mt8183_data = {
> +	.infracfg_sw_rst_num = MT8183_INFRACFG_SW_RST_NUM,

Same as above.

> +	.toprgu_sw_rst_num = MT8183_TOPRGU_SW_RST_NUM,
> +};
> +
> +static int toprgu_reset_update(struct reset_controller_dev *rcdev,
> +			       unsigned long id, bool assert)
> +{
> +	unsigned int tmp;
> +	unsigned long flags;
> +

This empty line can be removed.

> +	struct mtk_wdt_dev *data =
> +		 container_of(rcdev, struct mtk_wdt_dev, rcdev);
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +
> +	tmp = readl(data->wdt_base + WDT_SWSYSRST);
> +	if (assert)
> +		tmp |= BIT(id);
> +	else
> +		tmp &= ~BIT(id);
> +	tmp |= WDT_SWSYS_RST_KEY;
> +	writel(tmp, data->wdt_base + WDT_SWSYSRST);
> +
> +	spin_unlock_irqrestore(&data->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int toprgu_reset_assert(struct reset_controller_dev *rcdev,
> +			       unsigned long id)
> +{
> +	return toprgu_reset_update(rcdev, id, true);
> +}
> +
> +static int toprgu_reset_deassert(struct reset_controller_dev *rcdev,
> +				 unsigned long id)
> +{
> +	return toprgu_reset_update(rcdev, id, false);
> +}
> +
> +static int toprgu_reset(struct reset_controller_dev *rcdev,
> +			unsigned long id)
> +{
> +	int ret;
> +
> +	ret = toprgu_reset_assert(rcdev, id);
> +	if (ret)
> +		return ret;
> +
> +	return toprgu_reset_deassert(rcdev, id);
> +}

As mentioned above, is this needed? Does this work for all modules?
Only implement this if you are sure both are true.

regards
Philipp