[v5,1/2] bus: mhi: core: Introduce internal register poll helper function
diff mbox series

Message ID 1617047583-12104-2-git-send-email-bbhatt@codeaurora.org
State New, archived
Headers show
Series
  • Polling for MHI ready
Related show

Commit Message

Bhaumik Bhatt March 29, 2021, 7:53 p.m. UTC
Introduce helper function to allow MHI core driver to poll for
a value in a register field. This helps reach a common path to
read and poll register values along with a retry time interval.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
---
 drivers/bus/mhi/core/internal.h |  3 +++
 drivers/bus/mhi/core/main.c     | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+)

Comments

Manivannan Sadhasivam March 31, 2021, 1:03 p.m. UTC | #1
On Mon, Mar 29, 2021 at 12:53:02PM -0700, Bhaumik Bhatt wrote:
> Introduce helper function to allow MHI core driver to poll for
> a value in a register field. This helps reach a common path to
> read and poll register values along with a retry time interval.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> ---
>  drivers/bus/mhi/core/internal.h |  3 +++
>  drivers/bus/mhi/core/main.c     | 23 +++++++++++++++++++++++
>  2 files changed, 26 insertions(+)
> 
> diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
> index 6f80ec3..005286b 100644
> --- a/drivers/bus/mhi/core/internal.h
> +++ b/drivers/bus/mhi/core/internal.h
> @@ -643,6 +643,9 @@ int __must_check mhi_read_reg(struct mhi_controller *mhi_cntrl,
>  int __must_check mhi_read_reg_field(struct mhi_controller *mhi_cntrl,
>  				    void __iomem *base, u32 offset, u32 mask,
>  				    u32 shift, u32 *out);
> +int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
> +				    void __iomem *base, u32 offset, u32 mask,
> +				    u32 shift, u32 val, u32 delayus);
>  void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
>  		   u32 offset, u32 val);
>  void mhi_write_reg_field(struct mhi_controller *mhi_cntrl, void __iomem *base,
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 4e0131b..6f4b630 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -4,6 +4,7 @@
>   *
>   */
>  
> +#include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/dma-direction.h>
>  #include <linux/dma-mapping.h>
> @@ -37,6 +38,28 @@ int __must_check mhi_read_reg_field(struct mhi_controller *mhi_cntrl,
>  	return 0;
>  }
>  
> +int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
> +				    void __iomem *base, u32 offset,
> +				    u32 mask, u32 shift, u32 val, u32 delayus)
> +{
> +	int ret;
> +	u32 out, retry = (mhi_cntrl->timeout_ms * 1000) / delayus;
> +
> +	while (retry--) {
> +		ret = mhi_read_reg_field(mhi_cntrl, base, offset, mask, shift,
> +					 &out);
> +		if (ret)
> +			return ret;
> +
> +		if (out == val)
> +			return 0;
> +
> +		fsleep(delayus);
> +	}
> +
> +	return -ENOENT;

Maybe I'm too late on this one, but I don't think -ENOENT is the correct
error code here. The error code will be returned only when the reg field
value didn't change as expected, so in that case it should be -EINVAL or
-ETIMEDOUT, no?

Thanks,
Mani

> +}
> +
>  void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
>  		   u32 offset, u32 val)
>  {
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
Bhaumik Bhatt March 31, 2021, 5:09 p.m. UTC | #2
Hi Mani,

On 2021-03-31 06:03 AM, Manivannan Sadhasivam wrote:
> On Mon, Mar 29, 2021 at 12:53:02PM -0700, Bhaumik Bhatt wrote:
>> Introduce helper function to allow MHI core driver to poll for
>> a value in a register field. This helps reach a common path to
>> read and poll register values along with a retry time interval.
>> 
>> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
>> ---
>>  drivers/bus/mhi/core/internal.h |  3 +++
>>  drivers/bus/mhi/core/main.c     | 23 +++++++++++++++++++++++
>>  2 files changed, 26 insertions(+)
>> 
>> diff --git a/drivers/bus/mhi/core/internal.h 
>> b/drivers/bus/mhi/core/internal.h
>> index 6f80ec3..005286b 100644
>> --- a/drivers/bus/mhi/core/internal.h
>> +++ b/drivers/bus/mhi/core/internal.h
>> @@ -643,6 +643,9 @@ int __must_check mhi_read_reg(struct 
>> mhi_controller *mhi_cntrl,
>>  int __must_check mhi_read_reg_field(struct mhi_controller *mhi_cntrl,
>>  				    void __iomem *base, u32 offset, u32 mask,
>>  				    u32 shift, u32 *out);
>> +int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
>> +				    void __iomem *base, u32 offset, u32 mask,
>> +				    u32 shift, u32 val, u32 delayus);
>>  void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem 
>> *base,
>>  		   u32 offset, u32 val);
>>  void mhi_write_reg_field(struct mhi_controller *mhi_cntrl, void 
>> __iomem *base,
>> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
>> index 4e0131b..6f4b630 100644
>> --- a/drivers/bus/mhi/core/main.c
>> +++ b/drivers/bus/mhi/core/main.c
>> @@ -4,6 +4,7 @@
>>   *
>>   */
>> 
>> +#include <linux/delay.h>
>>  #include <linux/device.h>
>>  #include <linux/dma-direction.h>
>>  #include <linux/dma-mapping.h>
>> @@ -37,6 +38,28 @@ int __must_check mhi_read_reg_field(struct 
>> mhi_controller *mhi_cntrl,
>>  	return 0;
>>  }
>> 
>> +int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
>> +				    void __iomem *base, u32 offset,
>> +				    u32 mask, u32 shift, u32 val, u32 delayus)
>> +{
>> +	int ret;
>> +	u32 out, retry = (mhi_cntrl->timeout_ms * 1000) / delayus;
>> +
>> +	while (retry--) {
>> +		ret = mhi_read_reg_field(mhi_cntrl, base, offset, mask, shift,
>> +					 &out);
>> +		if (ret)
>> +			return ret;
>> +
>> +		if (out == val)
>> +			return 0;
>> +
>> +		fsleep(delayus);
>> +	}
>> +
>> +	return -ENOENT;
> 
> Maybe I'm too late on this one, but I don't think -ENOENT is the 
> correct
> error code here. The error code will be returned only when the reg 
> field
> value didn't change as expected, so in that case it should be -EINVAL 
> or
> -ETIMEDOUT, no?
> 
> Thanks,
> Mani
> 

Thanks for pointing that out.

The intention of the error code was despite polling for whatever time 
period,
we were unable to see the value changing as expected. I think the 
-ETIMEDOUT
error code would be appropriate. Will upload a v6.

>> +}
>> +
>>  void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem 
>> *base,
>>  		   u32 offset, u32 val)
>>  {
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project
>> 

Thanks,
Bhaumik
---
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum,
a Linux Foundation Collaborative Project

Patch
diff mbox series

diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 6f80ec3..005286b 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -643,6 +643,9 @@  int __must_check mhi_read_reg(struct mhi_controller *mhi_cntrl,
 int __must_check mhi_read_reg_field(struct mhi_controller *mhi_cntrl,
 				    void __iomem *base, u32 offset, u32 mask,
 				    u32 shift, u32 *out);
+int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
+				    void __iomem *base, u32 offset, u32 mask,
+				    u32 shift, u32 val, u32 delayus);
 void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
 		   u32 offset, u32 val);
 void mhi_write_reg_field(struct mhi_controller *mhi_cntrl, void __iomem *base,
diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 4e0131b..6f4b630 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -4,6 +4,7 @@ 
  *
  */
 
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/dma-direction.h>
 #include <linux/dma-mapping.h>
@@ -37,6 +38,28 @@  int __must_check mhi_read_reg_field(struct mhi_controller *mhi_cntrl,
 	return 0;
 }
 
+int __must_check mhi_poll_reg_field(struct mhi_controller *mhi_cntrl,
+				    void __iomem *base, u32 offset,
+				    u32 mask, u32 shift, u32 val, u32 delayus)
+{
+	int ret;
+	u32 out, retry = (mhi_cntrl->timeout_ms * 1000) / delayus;
+
+	while (retry--) {
+		ret = mhi_read_reg_field(mhi_cntrl, base, offset, mask, shift,
+					 &out);
+		if (ret)
+			return ret;
+
+		if (out == val)
+			return 0;
+
+		fsleep(delayus);
+	}
+
+	return -ENOENT;
+}
+
 void mhi_write_reg(struct mhi_controller *mhi_cntrl, void __iomem *base,
 		   u32 offset, u32 val)
 {