Re: [EXTERNAL] Re: [PATCH v11 3/6] remoteproc: pru: Add APIs to get and put the PRU cores

[Md Danish Anwar]

Hi Roger,

On 08/12/22 16:05, Roger Quadros wrote:
> Hi,
> 
> On 07/12/2022 13:04, MD Danish Anwar wrote:
>> Add two new APIs, pru_rproc_get() and pru_rproc_put(), to the PRU
>> driver to allow client drivers to acquire and release the remoteproc
>> device associated with a PRU core. The PRU cores are treated as
>> resources with only one client owning it at a time.
>>
>> The pru_rproc_get() function returns the rproc handle corresponding
>> to a PRU core identified by the device tree "ti,prus" property under
>> the client node. The pru_rproc_put() is the complementary function
>> to pru_rproc_get().
>>
>> Signed-off-by: Suman Anna <s-anna@xxxxxx>
>> Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>
>> Signed-off-by: MD Danish Anwar <danishanwar@xxxxxx>
>> ---
>>  drivers/remoteproc/pru_rproc.c | 133 ++++++++++++++++++++++++++++++++-
>>  include/linux/pruss.h          |  29 +++++++
>>  2 files changed, 160 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
>> index a1a208b31846..7d4ed39b3772 100644
>> --- a/drivers/remoteproc/pru_rproc.c
>> +++ b/drivers/remoteproc/pru_rproc.c
>> @@ -2,12 +2,14 @@
>>  /*
>>   * PRU-ICSS remoteproc driver for various TI SoCs
>>   *
>> - * Copyright (C) 2014-2020 Texas Instruments Incorporated - https://www.ti.com/
>> + * Copyright (C) 2014-2022 Texas Instruments Incorporated - https://www.ti.com/
>>   *
>>   * Author(s):
>>   *	Suman Anna <s-anna@xxxxxx>
>>   *	Andrew F. Davis <afd@xxxxxx>
>>   *	Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx> for Texas Instruments
>> + *	Puranjay Mohan <p-mohan@xxxxxx>
>> + *	Md Danish Anwar <danishanwar@xxxxxx>
>>   */
>>  
>>  #include <linux/bitops.h>
>> @@ -112,6 +114,8 @@ struct pru_private_data {
>>   * @rproc: remoteproc pointer for this PRU core
>>   * @data: PRU core specific data
>>   * @mem_regions: data for each of the PRU memory regions
>> + * @client_np: client device node
>> + * @lock: mutex to protect client usage
>>   * @fw_name: name of firmware image used during loading
>>   * @mapped_irq: virtual interrupt numbers of created fw specific mapping
>>   * @pru_interrupt_map: pointer to interrupt mapping description (firmware)
>> @@ -127,6 +131,8 @@ struct pru_rproc {
>>  	struct rproc *rproc;
>>  	const struct pru_private_data *data;
>>  	struct pruss_mem_region mem_regions[PRU_IOMEM_MAX];
>> +	struct device_node *client_np;
>> +	struct mutex lock;
>>  	const char *fw_name;
>>  	unsigned int *mapped_irq;
>>  	struct pru_irq_rsc *pru_interrupt_map;
>> @@ -147,6 +153,125 @@ void pru_control_write_reg(struct pru_rproc *pru, unsigned int reg, u32 val)
>>  	writel_relaxed(val, pru->mem_regions[PRU_IOMEM_CTRL].va + reg);
>>  }
>>  
>> +static struct rproc *__pru_rproc_get(struct device_node *np, int index)
>> +{
>> +	struct rproc *rproc;
>> +	phandle rproc_phandle;
>> +	int ret;
>> +
>> +	ret = of_property_read_u32_index(np, "ti,prus", index, &rproc_phandle);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	rproc = rproc_get_by_phandle(rproc_phandle);
>> +	if (!rproc) {
>> +		ret = -EPROBE_DEFER;
>> +		goto err_no_rproc_handle;
>> +	}
>> +
>> +	/* make sure it is PRU rproc */
>> +	if (!is_pru_rproc(rproc->dev.parent)) {
>> +		rproc_put(rproc);
>> +		return ERR_PTR(-ENODEV);
>> +	}
>> +
>> +	return rproc;
>> +
>> +err_no_rproc_handle:
>> +	rproc_put(rproc);
>> +	return ERR_PTR(ret);
>> +}
>> +
>> +/**
>> + * pru_rproc_get() - get the PRU rproc instance from a device node
>> + * @np: the user/client device node
>> + * @index: index to use for the ti,prus property
>> + * @pru_id: optional pointer to return the PRU remoteproc processor id
>> + *
>> + * This function looks through a client device node's "ti,prus" property at
>> + * index @index and returns the rproc handle for a valid PRU remote processor if
>> + * found. The function allows only one user to own the PRU rproc resource at a
>> + * time. Caller must call pru_rproc_put() when done with using the rproc, not
>> + * required if the function returns a failure.
>> + *
>> + * When optional @pru_id pointer is passed the PRU remoteproc processor id is
>> + * returned.
>> + *
>> + * Return: rproc handle on success, and an ERR_PTR on failure using one
>> + * of the following error values
>> + *    -ENODEV if device is not found
>> + *    -EBUSY if PRU is already acquired by anyone
>> + *    -EPROBE_DEFER is PRU device is not probed yet
>> + */
>> +struct rproc *pru_rproc_get(struct device_node *np, int index,
>> +			    enum pruss_pru_id *pru_id)
>> +{
>> +	struct rproc *rproc;
>> +	struct pru_rproc *pru;
>> +	struct device *dev;
>> +	int ret;
>> +
>> +	rproc = __pru_rproc_get(np, index);
>> +	if (IS_ERR(rproc))
>> +		return rproc;
>> +
>> +	pru = rproc->priv;
>> +	dev = &rproc->dev;
>> +
>> +	mutex_lock(&pru->lock);
>> +
>> +	if (pru->client_np) {
>> +		mutex_unlock(&pru->lock);
>> +		put_device(dev);
> 
> Is this put_device() to counter balance the get_device() you had earlier?
> Is it still needed?
>> Did we do the right thing by getting rid of the additional get_device()?
> I didn't see a reason for it.
> 

The previous get_device() in __pru_rproc_get() was additional/not required as
the same get_device() was called by rproc_get_by_phandle() API before it's
completion.

So that get_device() is not needed.

The put_device() here is to counter the get_device() called by
rproc_get_by_phandle() in the API __pru_rproc_get().

So I think, this put_device() is still needed.

>> +		ret = -EBUSY;
>> +		goto err_no_rproc_handle;
>> +	}
>> +
>> +	pru->client_np = np;
>> +
>> +	mutex_unlock(&pru->lock);
>> +
>> +	if (pru_id)
>> +		*pru_id = pru->id;
>> +
>> +	return rproc;
>> +
>> +err_no_rproc_handle:
>> +	rproc_put(rproc);
>> +	return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL_GPL(pru_rproc_get);
>> +
>> +/**
>> + * pru_rproc_put() - release the PRU rproc resource
>> + * @rproc: the rproc resource to release
>> + *
>> + * Releases the PRU rproc resource and makes it available to other
>> + * users.
>> + */
>> +void pru_rproc_put(struct rproc *rproc)
>> +{
>> +	struct pru_rproc *pru;
>> +
>> +	if (IS_ERR_OR_NULL(rproc) || !is_pru_rproc(rproc->dev.parent))
>> +		return;
>> +
>> +	pru = rproc->priv;
>> +
>> +	mutex_lock(&pru->lock);
>> +
>> +	if (!pru->client_np) {
>> +		mutex_unlock(&pru->lock);
>> +		return;
>> +	}
>> +
>> +	pru->client_np = NULL;
>> +	mutex_unlock(&pru->lock);
>> +
>> +	rproc_put(rproc);
>> +}
>> +EXPORT_SYMBOL_GPL(pru_rproc_put);
>> +
>>  static inline u32 pru_debug_read_reg(struct pru_rproc *pru, unsigned int reg)
>>  {
>>  	return readl_relaxed(pru->mem_regions[PRU_IOMEM_DEBUG].va + reg);
>> @@ -817,6 +942,8 @@ static int pru_rproc_probe(struct platform_device *pdev)
>>  	pru->pruss = platform_get_drvdata(ppdev);
>>  	pru->rproc = rproc;
>>  	pru->fw_name = fw_name;
>> +	pru->client_np = NULL;
>> +	mutex_init(&pru->lock);
>>  
>>  	for (i = 0; i < ARRAY_SIZE(mem_names); i++) {
>>  		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> @@ -905,7 +1032,7 @@ MODULE_DEVICE_TABLE(of, pru_rproc_match);
>>  
>>  static struct platform_driver pru_rproc_driver = {
>>  	.driver = {
>> -		.name   = "pru-rproc",
>> +		.name   = PRU_RPROC_DRVNAME,
>>  		.of_match_table = pru_rproc_match,
>>  		.suppress_bind_attrs = true,
>>  	},
>> @@ -917,5 +1044,7 @@ module_platform_driver(pru_rproc_driver);
>>  MODULE_AUTHOR("Suman Anna <s-anna@xxxxxx>");
>>  MODULE_AUTHOR("Andrew F. Davis <afd@xxxxxx>");
>>  MODULE_AUTHOR("Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>");
>> +MODULE_AUTHOR("Puranjay Mohan <p-mohan@xxxxxx>");
>> +MODULE_AUTHOR("Md Danish Anwar <danishanwar@xxxxxx>");
>>  MODULE_DESCRIPTION("PRU-ICSS Remote Processor Driver");
>>  MODULE_LICENSE("GPL v2");
>> diff --git a/include/linux/pruss.h b/include/linux/pruss.h
>> index fbe4fbb45807..6ea737e995e9 100644
>> --- a/include/linux/pruss.h
>> +++ b/include/linux/pruss.h
>> @@ -28,5 +28,34 @@ enum pruss_pru_id {
>>  	PRUSS_NUM_PRUS,
>>  };
>>  
>> +struct device_node;
>> +
>> +#if IS_ENABLED(CONFIG_PRU_REMOTEPROC)
>> +
>> +struct rproc *pru_rproc_get(struct device_node *np, int index,
>> +			    enum pruss_pru_id *pru_id);
>> +void pru_rproc_put(struct rproc *rproc);
>> +
>> +#else
>> +
>> +static inline struct rproc *
>> +pru_rproc_get(struct device_node *np, int index, enum pruss_pru_id *pru_id)
>> +{
>> +	return ERR_PTR(-EOPNOTSUPP);
>> +}
>> +
>> +static inline void pru_rproc_put(struct rproc *rproc) { }
>> +
>> +#endif /* CONFIG_PRU_REMOTEPROC */
>> +
>> +static inline bool is_pru_rproc(struct device *dev)
>> +{
>> +	const char *drv_name = dev_driver_string(dev);
>> +
>> +	if (strncmp(drv_name, PRU_RPROC_DRVNAME, sizeof(PRU_RPROC_DRVNAME)))
>> +		return false;
>> +
>> +	return true;
>> +}
>>  
>>  #endif /* __LINUX_PRUSS_H */
>> \ No newline at end of file
> 
> --
> cheers,
> -roger

Thanks,
Danish