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

[Yong Liang <yong.liang@mediatek.com>]

On Thu, 2019-12-12 at 00:44 +0800, Philipp Zabel wrote:
> Hi,
> 
> On Thu, 2019-12-12 at 00:22 +0800, Jiaxin Yu wrote:
> > From: "yong.liang" <yong.liang@mediatek.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.
> 
> > Audio use this reset API to reset audio, and it works well.
    It is no need to add delay between assert and deassert.

> > Signed-off-by: yong.liang <yong.liang@mediatek.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?

  It is no use. I will remove it.
> 
> >  #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.
  I will 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.
  I will remove it.
> 
> > +	.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.
  I will remove it.
> 
> > +	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.
  I think it's safe. Many modules has used it in MTK inside.
> 
> regards
> Philipp
> 

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