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[PATCH 2/3] i2c: k1: add reset support

Encrow Thorne posted 3 patches 2 months, 3 weeks ago
There is a newer version of this series
[PATCH 2/3] i2c: k1: add reset support
Posted by Encrow Thorne 2 months, 3 weeks ago 
Add reset control handling to the K1 I2C driver.

Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
---
 drivers/i2c/busses/i2c-k1.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c
index 6b918770e612..64d817d8315d 100644
--- a/drivers/i2c/busses/i2c-k1.c
+++ b/drivers/i2c/busses/i2c-k1.c
@@ -10,6 +10,7 @@
  #include <linux/module.h>
  #include <linux/of_address.h>
  #include <linux/platform_device.h>
+ #include <linux/reset.h>
 
 /* spacemit i2c registers */
 #define SPACEMIT_ICR		 0x0		/* Control register */
@@ -113,6 +114,7 @@ struct spacemit_i2c_dev {
 	void __iomem *base;
 	int irq;
 	u32 clock_freq;
+	struct reset_control *resets;
 
 	struct i2c_msg *msgs;
 	u32 msg_num;
@@ -571,6 +573,15 @@ static int spacemit_i2c_probe(struct platform_device *pdev)
 	if (IS_ERR(clk))
 		return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock");
 
+	i2c->resets = devm_reset_control_get_optional(dev, NULL);
+	if (IS_ERR(i2c->resets))
+		return dev_err_probe(dev, PTR_ERR(i2c->resets),
+				    "failed to get reset\n");
+
+	reset_control_assert(i2c->resets);
+	udelay(2);
+	reset_control_deassert(i2c->resets);
+
 	spacemit_i2c_reset(i2c);
 
 	i2c_set_adapdata(&i2c->adapt, i2c);

-- 
2.25.1
Re: [PATCH 2/3] i2c: k1: add reset support
Posted by Guodong Xu 2 months ago 
On Wed, Nov 19, 2025 at 07:46:44PM +0800, Encrow Thorne wrote:
> Add reset control handling to the K1 I2C driver.
>
> Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
> ---
>  drivers/i2c/busses/i2c-k1.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c
> index 6b918770e612..64d817d8315d 100644
> --- a/drivers/i2c/busses/i2c-k1.c
> +++ b/drivers/i2c/busses/i2c-k1.c
> @@ -10,6 +10,7 @@
>   #include <linux/module.h>
>   #include <linux/of_address.h>
>   #include <linux/platform_device.h>
> + #include <linux/reset.h>
>
>  /* spacemit i2c registers */
>  #define SPACEMIT_ICR		 0x0		/* Control register */
> @@ -113,6 +114,7 @@ struct spacemit_i2c_dev {
>  	void __iomem *base;
>  	int irq;
>  	u32 clock_freq;
> +	struct reset_control *resets;

Thanks for the patch! A few suggestions to simplify this:

The reset_control structure doesn't need to be stored in the device
struct since the devm API automatically manages the resource lifecycle.

>
>  	struct i2c_msg *msgs;
>  	u32 msg_num;
> @@ -571,6 +573,15 @@ static int spacemit_i2c_probe(struct platform_device *pdev)

Please use a local variable in the probe function instead:

       struct reset_control *rst;

>  	if (IS_ERR(clk))
>  		return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock");
>
> +	i2c->resets = devm_reset_control_get_optional(dev, NULL);

There is a new API, I would suggest this:
       rst = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);


> +	if (IS_ERR(i2c->resets))
> +		return dev_err_probe(dev, PTR_ERR(i2c->resets),
> +				    "failed to get reset\n");
> +
> +	reset_control_assert(i2c->resets);
> +	udelay(2);
> +	reset_control_deassert(i2c->resets);
> +

Why you need to call assert() then deassert()?
Wouldn't the single API fit?

Best regards,
Guodong

>  	spacemit_i2c_reset(i2c);
>
>  	i2c_set_adapdata(&i2c->adapt, i2c);
>
Re: [PATCH 2/3] i2c: k1: add reset support
Posted by Encrow Thorne 1 month, 3 weeks ago 
On Thu, Dec 11, 2025 at 03:35:26PM +0800, Guodong Xu wrote:
> On Wed, Nov 19, 2025 at 07:46:44PM +0800, Encrow Thorne wrote:
> > Add reset control handling to the K1 I2C driver.
> >
> > Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
> > ---
> >  drivers/i2c/busses/i2c-k1.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c
> > index 6b918770e612..64d817d8315d 100644
> > --- a/drivers/i2c/busses/i2c-k1.c
> > +++ b/drivers/i2c/busses/i2c-k1.c
> > @@ -10,6 +10,7 @@
> >   #include <linux/module.h>
> >   #include <linux/of_address.h>
> >   #include <linux/platform_device.h>
> > + #include <linux/reset.h>
> >
> >  /* spacemit i2c registers */
> >  #define SPACEMIT_ICR		 0x0		/* Control register */
> > @@ -113,6 +114,7 @@ struct spacemit_i2c_dev {
> >  	void __iomem *base;
> >  	int irq;
> >  	u32 clock_freq;
> > +	struct reset_control *resets;
> 
> Thanks for the patch! A few suggestions to simplify this:
> 
> The reset_control structure doesn't need to be stored in the device
> struct since the devm API automatically manages the resource lifecycle.
> 
> >
> >  	struct i2c_msg *msgs;
> >  	u32 msg_num;
> > @@ -571,6 +573,15 @@ static int spacemit_i2c_probe(struct platform_device *pdev)
> 
> Please use a local variable in the probe function instead:
> 
>        struct reset_control *rst;
> 
> >  	if (IS_ERR(clk))
> >  		return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock");
> >
> > +	i2c->resets = devm_reset_control_get_optional(dev, NULL);
>
  
> There is a new API, I would suggest this:
>        rst = devm_reset_control_get_optional_exclusive_deasserted(dev, NULL);
> 
> 
> > +	if (IS_ERR(i2c->resets))
> > +		return dev_err_probe(dev, PTR_ERR(i2c->resets),
> > +				    "failed to get reset\n");
> > +
> > +	reset_control_assert(i2c->resets);
> > +	udelay(2);
> > +	reset_control_deassert(i2c->resets);
> > +
> 
> Why you need to call assert() then deassert()?
> Wouldn't the single API fit?
> 
 Good point.
 
 Thank you for your suggestions, I will fix them in v2.

 				- Encrow
> Best regards,
> Guodong
> 
> >  	spacemit_i2c_reset(i2c);
> >
> >  	i2c_set_adapdata(&i2c->adapt, i2c);
> >
Re: [PATCH 2/3] i2c: k1: add reset support
Posted by Troy Mitchell 2 months, 3 weeks ago 
Hi Encrow,

On Wed, Nov 19, 2025 at 07:46:44PM +0800, Encrow Thorne wrote:
> Add reset control handling to the K1 I2C driver.
> 
> Signed-off-by: Encrow Thorne <jyc0019@gmail.com>
> ---
>  drivers/i2c/busses/i2c-k1.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c
> index 6b918770e612..64d817d8315d 100644
> --- a/drivers/i2c/busses/i2c-k1.c
> +++ b/drivers/i2c/busses/i2c-k1.c
> @@ -10,6 +10,7 @@
>   #include <linux/module.h>
>   #include <linux/of_address.h>
>   #include <linux/platform_device.h>
> + #include <linux/reset.h>
>  
>  /* spacemit i2c registers */
>  #define SPACEMIT_ICR		 0x0		/* Control register */
> @@ -113,6 +114,7 @@ struct spacemit_i2c_dev {
>  	void __iomem *base;
>  	int irq;
>  	u32 clock_freq;
> +	struct reset_control *resets;
>  
>  	struct i2c_msg *msgs;
>  	u32 msg_num;
> @@ -571,6 +573,15 @@ static int spacemit_i2c_probe(struct platform_device *pdev)
>  	if (IS_ERR(clk))
>  		return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock");
>  
> +	i2c->resets = devm_reset_control_get_optional(dev, NULL);
> +	if (IS_ERR(i2c->resets))
> +		return dev_err_probe(dev, PTR_ERR(i2c->resets),
> +				    "failed to get reset\n");
Please align.

> +
> +	reset_control_assert(i2c->resets);
> +	udelay(2);
This seems to be a very small value. If this
has been verified multiple times?

                        - Troy
> +	reset_control_deassert(i2c->resets);
> +
>  	spacemit_i2c_reset(i2c);
>  
>  	i2c_set_adapdata(&i2c->adapt, i2c);
> 
> -- 
> 2.25.1
> 
>

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