Re: [EXTERNAL] Re: [PATCH v4 4/5] soc: ti: pruss: Add helper functions to set GPI mode, MII_RT_event and XFR

[Md Danish Anwar <a0501179@ti.com>]

On 16/03/23 17:49, Roger Quadros wrote:
> 
> 
> On 16/03/2023 13:44, Md Danish Anwar wrote:
>>
>> On 16/03/23 17:06, Roger Quadros wrote:
>>> Hi,
>>>
>>> On 16/03/2023 13:05, Md Danish Anwar wrote:
>>>> Hi Roger,
>>>>
>>>> On 15/03/23 17:52, Roger Quadros wrote:
>>>>>
>>>>>
>>>>> On 13/03/2023 13:11, MD Danish Anwar wrote:
>>>>>> From: Suman Anna <s-anna@ti.com>
>>>>>>
>>>>>> The PRUSS CFG module is represented as a syscon node and is currently
>>>>>> managed by the PRUSS platform driver. Add easy accessor functions to set
>>>>>> GPI mode, MII_RT event enable/disable and XFR (XIN XOUT) enable/disable
>>>>>> to enable the PRUSS Ethernet usecase. These functions reuse the generic
>>>>>> pruss_cfg_update() API function.
>>>>>>
>>>>>> Signed-off-by: Suman Anna <s-anna@ti.com>
>>>>>> Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
>>>>>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@linaro.org>
>>>>>> Signed-off-by: Puranjay Mohan <p-mohan@ti.com>
>>>>>> Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
>>>>>> ---
>>>>>>  drivers/soc/ti/pruss.c           | 60 ++++++++++++++++++++++++++++++++
>>>>>>  include/linux/remoteproc/pruss.h | 22 ++++++++++++
>>>>>>  2 files changed, 82 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
>>>>>> index 26d8129b515c..2f04b7922ddb 100644
>>>>>> --- a/drivers/soc/ti/pruss.c
>>>>>> +++ b/drivers/soc/ti/pruss.c
>>>>>> @@ -203,6 +203,66 @@ static int pruss_cfg_update(struct pruss *pruss, unsigned int reg,
>>>>>>  	return regmap_update_bits(pruss->cfg_regmap, reg, mask, val);
>>>>>>  }
>>>>>>  
>>>>>> +/**
>>>>>> + * pruss_cfg_gpimode() - set the GPI mode of the PRU
>>>>>> + * @pruss: the pruss instance handle
>>>>>> + * @pru_id: id of the PRU core within the PRUSS
>>>>>> + * @mode: GPI mode to set
>>>>>> + *
>>>>>> + * Sets the GPI mode for a given PRU by programming the
>>>>>> + * corresponding PRUSS_CFG_GPCFGx register
>>>>>> + *
>>>>>> + * Return: 0 on success, or an error code otherwise
>>>>>> + */
>>>>>> +int pruss_cfg_gpimode(struct pruss *pruss, enum pruss_pru_id pru_id,
>>>>>> +		      enum pruss_gpi_mode mode)
>>>>>> +{
>>>>>> +	if (pru_id < 0 || pru_id >= PRUSS_NUM_PRUS)
>>>>>> +		return -EINVAL;
>>>>>> +
>>>>>> +	if (mode < 0 || mode > PRUSS_GPI_MODE_MAX)
>>>>>> +		return -EINVAL;
>>>>>> +
>>>>>> +	return pruss_cfg_update(pruss, PRUSS_CFG_GPCFG(pru_id),
>>>>>> +				PRUSS_GPCFG_PRU_GPI_MODE_MASK,
>>>>>> +				mode << PRUSS_GPCFG_PRU_GPI_MODE_SHIFT);
>>>>>> +}
>>>>>> +EXPORT_SYMBOL_GPL(pruss_cfg_gpimode);
>>>>>> +
>>>>>> +/**
>>>>>> + * pruss_cfg_miirt_enable() - Enable/disable MII RT Events
>>>>>> + * @pruss: the pruss instance
>>>>>> + * @enable: enable/disable
>>>>>> + *
>>>>>> + * Enable/disable the MII RT Events for the PRUSS.
>>>>>> + *
>>>>>> + * Return: 0 on success, or an error code otherwise
>>>>>> + */
>>>>>> +int pruss_cfg_miirt_enable(struct pruss *pruss, bool enable)
>>>>>> +{
>>>>>> +	u32 set = enable ? PRUSS_MII_RT_EVENT_EN : 0;
>>>>>> +
>>>>>> +	return pruss_cfg_update(pruss, PRUSS_CFG_MII_RT,
>>>>>> +				PRUSS_MII_RT_EVENT_EN, set);
>>>>>> +}
>>>>>> +EXPORT_SYMBOL_GPL(pruss_cfg_miirt_enable);
>>>>>> +
>>>>>> +/**
>>>>>> + * pruss_cfg_xfr_enable() - Enable/disable XIN XOUT shift functionality
>>>>>> + * @pruss: the pruss instance
>>>>>> + * @enable: enable/disable
>>>>>> + * @mask: Mask for PRU / RTU
>>>>>
>>>>> You should not expect the user to provide the mask but only
>>>>> the core type e.g. 
>>>>>
>>>>> enum pru_type {
>>>>>         PRU_TYPE_PRU = 0,
>>>>>         PRU_TYPE_RTU,
>>>>>         PRU_TYPE_TX_PRU,
>>>>>         PRU_TYPE_MAX,
>>>>> };
>>>>>
>>>>> Then you figure out the mask in the function.
>>>>> Also check for invalid pru_type and return error if so.
>>>>>
>>>>
>>>> Sure Roger, I will create a enum and take it as parameter in API. Based on
>>>> these enum I will calculate mask and do XFR shifting inside the API
>>>> pruss_cfg_xfr_enable().
>>>>
>>>> There are two registers for XFR shift.
>>>>
>>>> #define PRUSS_SPP_XFER_SHIFT_EN                 BIT(1)
>>>> #define PRUSS_SPP_RTU_XFR_SHIFT_EN              BIT(3)
>>>>
>>>> For PRU XFR shifting, the mask should be PRUSS_SPP_XFER_SHIFT_EN,
>>>> for RTU shifting mask should be PRUSS_SPP_RTU_XFR_SHIFT_EN and for PRU and RTU
>>>> shifting mask should be (PRUSS_SPP_XFER_SHIFT_EN | PRUSS_SPP_RTU_XFR_SHIFT_EN)
>>>>
>>>> So the enum would be something like this.
>>>>
>>>> /**
>>>>  * enum xfr_shift_type - XFR shift type
>>>>  * @XFR_SHIFT_PRU: Enables XFR shift for PRU
>>>>  * @XFR_SHIFT_RTU: Enables XFR shift for RTU
>>>>  * @XFR_SHIFT_PRU_RTU: Enables XFR shift for both PRU and RTU
>>>
>>> This is not required. User can call the API twice. once for PRU and once for RTU.
>>>
>>>>  * @XFR_SHIFT_MAX: Total number of XFR shift types available.
>>>>  *
>>>>  */
>>>>
>>>> enum xfr_shift_type {
>>>>         XFR_SHIFT_PRU = 0,
>>>>         XFR_SHIFT_RTU,
>>>>         XFR_SHIFT_PRU_RTU,
>>>>         XFR_SHIFT_MAX,
>>>> };
>>>
>>> Why do you need this new enum definition?
>>> We already have pru_type defined somewhere. You can move it to a public header
>>> if not there yet.
>>>
>>> enum pru_type {
>>>          PRU_TYPE_PRU = 0,
>>>          PRU_TYPE_RTU,
>>>          PRU_TYPE_TX_PRU,
>>>          PRU_TYPE_MAX,
>>> };
>>>
>>
>> This enum is present in drivers/remoteproc/pru_rproc.c file. But the problem
>> with this enum is that in [1] we need to enable XFR shift for both PRU and RTU
>> for which the mask will be OR of PRUSS_SPP_XFER_SHIFT_EN (mask for PRU) and
>> PRUSS_SPP_RTU_XFR_SHIFT_EN (mask of RTU).
> 
> Is there any limitation that you have to enable both simultaneously?
> The driver can first do enable for PRU and then later for RTU.
> 
> As you will do a read modify write, the previous enable state of register
> shouldn't be affected.
> 
>>
>> Now this enum doesn't have a field for both PRU and RTU. Also we don't need
>> need the XFR shift for PRU_TYPE_TX_PRU as only two XFR shift register bits are
>> defined.
> 
> That is OK. You can return error if not RTU or PRU.
> 
>>
>> That is why I thought of introducing new enum.
>>
>> [1] drivers/net/ethernet/ti/icssg_config.c
>>
>> /* enable XFR shift for PRU and RTU */
>> 	mask = PRUSS_SPP_XFER_SHIFT_EN | PRUSS_SPP_RTU_XFR_SHIFT_EN;
> 
> Driver can do like so
> 
> 	pruss_cfg_xfr_enable(pruss, PRU_TYPE_PRU, true);
> 	pruss_cfg_xfr_enable(pruss, PRU_TYPE_RTU, true);
> 
> The second call should not disable the PRU XFR as you will do a
> read-modify-write only affecting the RTU bit.

Sure, then I will use the existing enum pru_type.

The enum pru_type is currently in drivers/remoteproc/pruss.c I will move this
enum definition from there to include/linux/remoteproc/pruss.h

> 
> cheers,
> -roger

-- 
Thanks and Regards,
Danish.