[EXTERNAL] Re: [PATCH v7 2/5] remoteproc: pru: Add APIs to get and put the PRU cores

[Md Danish Anwar]

Hi Roger,

I had responded to two of your comments on this patch earlier but missed one
comment. Responding to that comment now.

On 04/11/22 18:25, Roger Quadros wrote:
> Hi Danish,
> 
> On 31/10/2022 09:37, MD Danish Anwar wrote:
>> From: Tero Kristo <t-kristo at ti.com>
>>
>> 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().
>>
>> Co-developed-by: Suman Anna <s-anna at ti.com>
>> Signed-off-by: Suman Anna <s-anna at ti.com>
>> Signed-off-by: Tero Kristo <t-kristo at ti.com>
>> Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk at linaro.org>
>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk at linaro.org>
>> Co-developed-by: Puranjay Mohan <p-mohan at ti.com>
>> Signed-off-by: Puranjay Mohan <p-mohan at ti.com>
>> Signed-off-by: MD Danish Anwar <danishanwar at ti.com>
>> ---
>>  drivers/remoteproc/pru_rproc.c | 142 +++++++++++++++++++++++++++++++--
>>  include/linux/pruss.h          |  56 +++++++++++++
>>  2 files changed, 193 insertions(+), 5 deletions(-)
>>  create mode 100644 include/linux/pruss.h
>>
>> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
>> index 128bf9912f2c..9ba73cfc29e2 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 at ti.com>
>>   *	Andrew F. Davis <afd at ti.com>
>>   *	Grzegorz Jaszczyk <grzegorz.jaszczyk at linaro.org> for Texas Instruments
>> + *	Puranjay Mohan <p-mohan at ti.com>
>> + *	Md Danish Anwar <danishanwar at ti.com>
>>   */
>>  
>>  #include <linux/bitops.h>
>> @@ -16,6 +18,7 @@
>>  #include <linux/module.h>
>>  #include <linux/of_device.h>
>>  #include <linux/of_irq.h>
>> +#include <linux/pruss.h>
>>  #include <linux/pruss_driver.h>
>>  #include <linux/remoteproc.h>
>>  
>> @@ -111,6 +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)
>> @@ -126,6 +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; /* client access lock */
>>  	const char *fw_name;
>>  	unsigned int *mapped_irq;
>>  	struct pru_irq_rsc *pru_interrupt_map;
>> @@ -146,6 +153,127 @@ 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);
>> +	}
>> +
>> +	get_device(&rproc->dev);
> 
> Why do you need a get_device() here?
> rproc_get_by_phandle() does it right?
> 
>> +
>> +	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;
> 
> Why bother doing __pru_rproc_get() if pru->client_np exists?
> 
> You could do the below if check first and exit if pru->client_np exists.
> 
>> +
>> +	pru = rproc->priv;
>> +	dev = &rproc->dev;
>> +
>> +	mutex_lock(&pru->lock);
>> +
>> +	if (pru->client_np) {
>> +		mutex_unlock(&pru->lock);
>> +		put_device(dev);
>> +		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);
>> @@ -438,7 +566,7 @@ static void *pru_d_da_to_va(struct pru_rproc *pru, u32 da, size_t len)
>>  	dram0 = pruss->mem_regions[PRUSS_MEM_DRAM0];
>>  	dram1 = pruss->mem_regions[PRUSS_MEM_DRAM1];
>>  	/* PRU1 has its local RAM addresses reversed */
>> -	if (pru->id == 1)
>> +	if (pru->id == PRUSS_PRU1)
> 
> Introduction of PRUSS_PRU0/1 enum could have been a separate patch.
>

Yes, Introduction of PRUSS_PRU0/1 enum could have been a separated patch in the
same series. But from the v1 of this series, this enum has been part of this
patch and that's why I kept it that way. We can introduce a new patch for this
enum (and the APIs that are using the enum) in next version of the series if
it's okay with you and Mathieu.

>>  		swap(dram0, dram1);
>>  	shrd_ram = pruss->mem_regions[PRUSS_MEM_SHRD_RAM2];
>>  
>> @@ -747,14 +875,14 @@ static int pru_rproc_set_id(struct pru_rproc *pru)
>>  	case RTU0_IRAM_ADDR_MASK:
>>  		fallthrough;
>>  	case PRU0_IRAM_ADDR_MASK:
>> -		pru->id = 0;
>> +		pru->id = PRUSS_PRU0;
>>  		break;
>>  	case TX_PRU1_IRAM_ADDR_MASK:
>>  		fallthrough;
>>  	case RTU1_IRAM_ADDR_MASK:
>>  		fallthrough;
>>  	case PRU1_IRAM_ADDR_MASK:
>> -		pru->id = 1;
>> +		pru->id = PRUSS_PRU1;
>>  		break;
>>  	default:
>>  		ret = -EINVAL;
>> @@ -816,6 +944,8 @@ 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,
>> @@ -904,7 +1034,7 @@ 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,
>>  	},
>> @@ -916,5 +1046,7 @@ module_platform_driver(pru_rproc_driver);
>>  MODULE_AUTHOR("Suman Anna <s-anna at ti.com>");
>>  MODULE_AUTHOR("Andrew F. Davis <afd at ti.com>");
>>  MODULE_AUTHOR("Grzegorz Jaszczyk <grzegorz.jaszczyk at linaro.org>");
>> +MODULE_AUTHOR("Puranjay Mohan <p-mohan at ti.com>");
>> +MODULE_AUTHOR("Md Danish Anwar <danishanwar at ti.com>");
>>  MODULE_DESCRIPTION("PRU-ICSS Remote Processor Driver");
>>  MODULE_LICENSE("GPL v2");
>> diff --git a/include/linux/pruss.h b/include/linux/pruss.h
>> new file mode 100644
>> index 000000000000..fdc719b43db0
>> --- /dev/null
>> +++ b/include/linux/pruss.h
>> @@ -0,0 +1,56 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/**
>> + * PRU-ICSS Subsystem user interfaces
>> + *
>> + * Copyright (C) 2015-2022 Texas Instruments Incorporated - http://www.ti.com
>> + *	Suman Anna <s-anna at ti.com>
>> + */
>> +
>> +#ifndef __LINUX_PRUSS_H
>> +#define __LINUX_PRUSS_H
>> +
>> +#include <linux/device.h>
>> +#include <linux/types.h>
>> +
>> +#define PRU_RPROC_DRVNAME "pru-rproc"
>> +
>> +/*
>> + * enum pruss_pru_id - PRU core identifiers
>> + */
>> +enum pruss_pru_id {
>> +	PRUSS_PRU0 = 0,
>> +	PRUSS_PRU1,
>> +	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 */
> 
> cheers,
> -roger

Thanks,
Danish.