Date:   Thu, 8 Dec 2022 12:35:01 +0200
From:   Roger Quadros <rogerq@...nel.org>
To:     MD Danish Anwar <danishanwar@...com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
Cc:     Suman Anna <s-anna@...com>, "Andrew F . Davis" <afd@...com>,
        nm@...com, vigneshr@...com, srk@...com,
        linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v11 3/6] remoteproc: pru: Add APIs to get and put the PRU
 cores

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@...com>
> Signed-off-by: Tero Kristo <t-kristo@...com>
> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
> Signed-off-by: MD Danish Anwar <danishanwar@...com>
> ---
>  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@...com>
>   *	Andrew F. Davis <afd@...com>
>   *	Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org> for Texas Instruments
> + *	Puranjay Mohan <p-mohan@...com>
> + *	Md Danish Anwar <danishanwar@...com>
>   */
>  
>  #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.

> +		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@...com>");
>  MODULE_AUTHOR("Andrew F. Davis <afd@...com>");
>  MODULE_AUTHOR("Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>");
> +MODULE_AUTHOR("Puranjay Mohan <p-mohan@...com>");
> +MODULE_AUTHOR("Md Danish Anwar <danishanwar@...com>");
>  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

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