Re: [EXTERNAL] Re: [EXTERNAL] Re: [PATCH v3 5/6] soc: ti: pruss: Add helper function to enable OCP master ports

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

On 08/03/23 16:44, Roger Quadros wrote:
> 
> 
> On 08/03/2023 13:09, Md Danish Anwar wrote:
>> Hi Roger,
>>
>> On 08/03/23 14:11, Roger Quadros wrote:
>>>
>>>
>>> On 06/03/2023 13:09, MD Danish Anwar wrote:
>>>> From: Suman Anna <s-anna@ti.com>
>>>>
>>>> The PRU-ICSS subsystem on OMAP-architecture based SoCS (AM33xx, AM437x
>>>> and AM57xx SoCs) has a control bit STANDBY_INIT in the PRUSS_CFG register
>>>> to initiate a Standby sequence (when set) and trigger a MStandby request
>>>> to the SoC's PRCM module. This same bit is also used to enable the OCP
>>>> master ports (when cleared). The clearing of the STANDBY_INIT bit requires
>>>> an acknowledgment from PRCM and is done through the monitoring of the
>>>> PRUSS_SYSCFG.SUB_MWAIT bit.
>>>>
>>>> Add a helper function pruss_cfg_ocp_master_ports() to allow the PRU
>>>> client drivers to control this bit and enable or disable the firmware
>>>> running on PRU cores access to any peripherals or memory to achieve
>>>> desired functionality. The access is disabled by default on power-up
>>>> and on any suspend (context is not maintained).
>>>>
>>>> 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>
>>>> ---
>>>>  drivers/soc/ti/pruss.c           | 81 +++++++++++++++++++++++++++++++-
>>>>  include/linux/remoteproc/pruss.h |  6 +++
>>>>  2 files changed, 85 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
>>>> index 537a3910ffd8..dc3abda0b8c2 100644
>>>> --- a/drivers/soc/ti/pruss.c
>>>> +++ b/drivers/soc/ti/pruss.c
>>>> @@ -22,14 +22,19 @@
>>>>  #include <linux/remoteproc.h>
>>>>  #include <linux/slab.h>
>>>>  
>>>> +#define SYSCFG_STANDBY_INIT	BIT(4)
>>>> +#define SYSCFG_SUB_MWAIT_READY	BIT(5)
>>>> +
>>>>  /**
>>>>   * struct pruss_private_data - PRUSS driver private data
>>>>   * @has_no_sharedram: flag to indicate the absence of PRUSS Shared Data RAM
>>>>   * @has_core_mux_clock: flag to indicate the presence of PRUSS core clock
>>>> + * @has_ocp_syscfg: flag to indicate if OCP SYSCFG is present
>>>>   */
>>>>  struct pruss_private_data {
>>>>  	bool has_no_sharedram;
>>>>  	bool has_core_mux_clock;
>>>> +	bool has_ocp_syscfg;
>>>>  };
>>>>  
>>>>  /**
>>>> @@ -205,6 +210,72 @@ int pruss_cfg_update(struct pruss *pruss, unsigned int reg,
>>>>  }
>>>>  EXPORT_SYMBOL_GPL(pruss_cfg_update);
>>>>  
>>>> +/**
>>>> + * pruss_cfg_ocp_master_ports() - configure PRUSS OCP master ports
>>>> + * @pruss: the pruss instance handle
>>>> + * @enable: set to true for enabling or false for disabling the OCP master ports
>>>> + *
>>>> + * This function programs the PRUSS_SYSCFG.STANDBY_INIT bit either to enable or
>>>> + * disable the OCP master ports (applicable only on SoCs using OCP interconnect
>>>> + * like the OMAP family). Clearing the bit achieves dual functionalities - one
>>>> + * is to deassert the MStandby signal to the device PRCM, and the other is to
>>>> + * enable OCP master ports to allow accesses outside of the PRU-ICSS. The
>>>> + * function has to wait for the PRCM to acknowledge through the monitoring of
>>>> + * the PRUSS_SYSCFG.SUB_MWAIT bit when enabling master ports. Setting the bit
>>>> + * disables the master access, and also signals the PRCM that the PRUSS is ready
>>>> + * for Standby.
>>>> + *
>>>> + * Return: 0 on success, or an error code otherwise. ETIMEDOUT is returned
>>>> + * when the ready-state fails.
>>>> + */
>>>> +int pruss_cfg_ocp_master_ports(struct pruss *pruss, bool enable)
>>>> +{
>>>> +	int ret;
>>>> +	u32 syscfg_val, i;
>>>> +	const struct pruss_private_data *data;
>>>> +
>>>> +	if (IS_ERR_OR_NULL(pruss))
>>>> +		return -EINVAL;
>>>> +
>>>> +	data = of_device_get_match_data(pruss->dev);
>>>> +
>>>> +	/* nothing to do on non OMAP-SoCs */
>>>> +	if (!data || !data->has_ocp_syscfg)
>>>> +		return 0;
>>>> +
>>>> +	/* assert the MStandby signal during disable path */
>>>> +	if (!enable)
>>>> +		return pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG,
>>>> +					SYSCFG_STANDBY_INIT,
>>>> +					SYSCFG_STANDBY_INIT);
>>>
>>> You can omit the above if() if you just encapsulate the below in
>>>
>>> if (enable) {
>>>
>>>
>> Sure, I can omit the above if() and put the below block inside if (enable) {}.
>>
>> Currently when API pruss_cfg_ocp_master_ports()is called with enable as false
>> i.e. disabling PRUSS OCP master ports is requested, we directly return
>> pruss_cfg_update() where as if we remove the above if() section and encapsulate
>> below block in if (enable) {}, then in disable scenario, call flow will
>> directly reach the label disable. In the label disable, we are updating cfg and
>> then returning "ret", but at this point the variable ret is not assigned.
>>
>> To counter this should I change the label disable to below?
>>
>> disable:
>> 	return pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG, SYSCFG_STANDBY_INIT,
>> 			 SYSCFG_STANDBY_INIT);
> 
> But you will loose the error code if we came here due to failure in pruss_cfg_read().
> 

Yes that's why I think it's better to leave it as it is.

> It's ok, don't make the change I suggested and leave it as it is.
> 

Sure

>>
>>>> +
>>>> +	/* enable the OCP master ports and disable MStandby */
>>>> +	ret = pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG, SYSCFG_STANDBY_INIT, 0);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	/* wait till we are ready for transactions - delay is arbitrary */
>>>> +	for (i = 0; i < 10; i++) {
>>>> +		ret = pruss_cfg_read(pruss, PRUSS_CFG_SYSCFG, &syscfg_val);
>>>> +		if (ret)
>>>> +			goto disable;
>>>> +
>>
>> Changing the disable label will also result in losing the return value of
>> pruss_cfg_read() API call here.
>>
>>>> +		if (!(syscfg_val & SYSCFG_SUB_MWAIT_READY))
>>>> +			return 0;
>>>> +
>>>> +		udelay(5);
>>>> +	}
>>>> +
>>>> +	dev_err(pruss->dev, "timeout waiting for SUB_MWAIT_READY\n");
>>>> +	ret = -ETIMEDOUT;
>>
>> Changing the disable label will also result in losing ret = -ETIMEDOUT here.
>>
>>>
>>> }
>>>
>>>> +
>>>> +disable:
>>>> +	pruss_cfg_update(pruss, PRUSS_CFG_SYSCFG, SYSCFG_STANDBY_INIT,
>>>> +			 SYSCFG_STANDBY_INIT);
>>>> +	return ret;
>>>> +}
>>
>> So should I do this modification or keep it as it is?
>>
>>>> +EXPORT_SYMBOL_GPL(pruss_cfg_ocp_master_ports);
>>>> +
>>>>  static void pruss_of_free_clk_provider(void *data)
>>>>  {
>>>>  	struct device_node *clk_mux_np = data;
>>>> @@ -495,10 +566,16 @@ static int pruss_remove(struct platform_device *pdev)
>>>>  /* instance-specific driver private data */
>>>>  static const struct pruss_private_data am437x_pruss1_data = {
>>>>  	.has_no_sharedram = false,
>>>> +	.has_ocp_syscfg = true,
>>>>  };
>>>>  
>>>>  static const struct pruss_private_data am437x_pruss0_data = {
>>>>  	.has_no_sharedram = true,
>>>> +	.has_ocp_syscfg = false,
>>>> +};
>>>> +
>>>> +static const struct pruss_private_data am33xx_am57xx_data = {
>>>> +	.has_ocp_syscfg = true,
>>>>  };
>>>
>>> How about keeping platform data for different platforms separate?
>>>
>>> i.e. am33xx_pruss_data and am57xx_pruss_data
>>>
>>
>> Sure. I'll split am33xx_am57xx_data into am33xx_pruss_data and
>> am57xx_pruss_data as well as am65x_j721e_pruss_data into am65x_pruss_data and
>> j721e_pruss_data.
>>
>>>>  
>>>>  static const struct pruss_private_data am65x_j721e_pruss_data = {
>>>> @@ -506,10 +583,10 @@ static const struct pruss_private_data am65x_j721e_pruss_data = {
>>>>  };
>>>>  
>>>>  static const struct of_device_id pruss_of_match[] = {
>>>> -	{ .compatible = "ti,am3356-pruss" },
>>>> +	{ .compatible = "ti,am3356-pruss", .data = &am33xx_am57xx_data },
>>>>  	{ .compatible = "ti,am4376-pruss0", .data = &am437x_pruss0_data, },
>>>>  	{ .compatible = "ti,am4376-pruss1", .data = &am437x_pruss1_data, },
>>>> -	{ .compatible = "ti,am5728-pruss" },
>>>> +	{ .compatible = "ti,am5728-pruss", .data = &am33xx_am57xx_data },
>>>>  	{ .compatible = "ti,k2g-pruss" },
>>>>  	{ .compatible = "ti,am654-icssg", .data = &am65x_j721e_pruss_data, },
>>>>  	{ .compatible = "ti,j721e-icssg", .data = &am65x_j721e_pruss_data, },
>>>> diff --git a/include/linux/remoteproc/pruss.h b/include/linux/remoteproc/pruss.h
>>>> index 7952f250301a..8cb99d3cad0d 100644
>>>> --- a/include/linux/remoteproc/pruss.h
>>>> +++ b/include/linux/remoteproc/pruss.h
>>>> @@ -168,6 +168,7 @@ int pruss_release_mem_region(struct pruss *pruss,
>>>>  int pruss_cfg_read(struct pruss *pruss, unsigned int reg, unsigned int *val);
>>>>  int pruss_cfg_update(struct pruss *pruss, unsigned int reg,
>>>>  		     unsigned int mask, unsigned int val);
>>>> +int pruss_cfg_ocp_master_ports(struct pruss *pruss, bool enable);
>>>>  
>>>>  #else
>>>>  
>>>> @@ -203,6 +204,11 @@ static inline int pruss_cfg_update(struct pruss *pruss, unsigned int reg,
>>>>  	return -EOPNOTSUPP;
>>>>  }
>>>>  
>>>> +static inline int pruss_cfg_ocp_master_ports(struct pruss *pruss, bool enable)
>>>> +{
>>>> +	return -EOPNOTSUPP;
>>>> +}
>>>> +
>>>>  #endif /* CONFIG_TI_PRUSS */
>>>>  
>>>>  #if IS_ENABLED(CONFIG_PRU_REMOTEPROC)
>>>
>>> cheers,
>>> -roger
>>
> 
> cheers,
> -roger

-- 
Thanks and Regards,
Danish.