Message-ID: <20718115-7606-a77b-7e4d-511ca9c1d798@ti.com>
Date:   Thu, 16 Mar 2023 17:14:59 +0530
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Subject: Re: [PATCH v4 4/5] soc: ti: pruss: Add helper functions to set GPI
 mode, MII_RT_event and XFR
Content-Language: en-US
To:     Roger Quadros <rogerq@kernel.org>,
        MD Danish Anwar <danishanwar@ti.com>,
        "Andrew F. Davis" <afd@ti.com>, Suman Anna <s-anna@ti.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Nishanth Menon <nm@ti.com>
CC:     <linux-remoteproc@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <linux-omap@vger.kernel.org>,
        <srk@ti.com>, <devicetree@vger.kernel.org>,
        <netdev@vger.kernel.org>
References: <20230313111127.1229187-1-danishanwar@ti.com>
 <20230313111127.1229187-5-danishanwar@ti.com>
 <d168e7dd-42a0-b728-5c4c-e97209c13871@kernel.org>
 <b1409f34-86b5-14e8-f352-5032aa57ca46@ti.com>
 <60e73395-f670-6eaa-0eb7-389553320a71@kernel.org>
From:   Md Danish Anwar <a0501179@ti.com>
Organization: Texas Instruments
In-Reply-To: <60e73395-f670-6eaa-0eb7-389553320a71@kernel.org>
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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).

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 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;
> 
>>
>> In pruss_cfg_xfr_enable() API, I will use switch case, and for first three
>> enums, I will calculate the mask.
>>
>> If input is anything other than first three, I will retun -EINVAL. This will
>> serve as check for valid xfr_shift_type.
>>
>> The API will look like this.
>>
>> int pruss_cfg_xfr_enable(struct pruss *pruss, enum xfr_shift_type xfr_type,
>> 			 bool enable);
>> {
>> 	u32 mask;
>>
>> 	switch (xfr_type) {
>> 	case XFR_SHIFT_PRU:
>> 		mask = PRUSS_SPP_XFER_SHIFT_EN;
>> 		break;
>> 	case XFR_SHIFT_RTU:
>> 		mask = PRUSS_SPP_RTU_XFR_SHIFT_EN;
>> 		break;
>> 	case XFR_SHIFT_PRU_RTU:
>> 		mask = PRUSS_SPP_XFER_SHIFT_EN | PRUSS_SPP_RTU_XFR_SHIFT_EN;
>> 		break;
>> 	default:
>> 		return -EINVAL;
>> 	}
>>
>> 	u32 set = enable ? mask : 0;
>>
>> 	return pruss_cfg_update(pruss, PRUSS_CFG_SPP, mask, set);
>> }
>>
>> This entire change I will keep as part of this patch only.
>>
>> Please let me know if this looks OK to you.
>>
>>
> 
> cheers,
> -roger

-- 
Thanks and Regards,
Danish.