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Date:   Mon, 27 Mar 2023 14:58:41 -0600
From:   Mathieu Poirier <mathieu.poirier@linaro.org>
To:     MD Danish Anwar <danishanwar@ti.com>
Cc:     "Andrew F. Davis" <afd@ti.com>, Suman Anna <s-anna@ti.com>,
        Roger Quadros <rogerq@kernel.org>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Tero Kristo <kristo@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Nishanth Menon <nm@ti.com>, 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
Subject: Re: [PATCH v5 1/5] soc: ti: pruss: Add pruss_get()/put() API
Message-ID: <20230327205841.GA3158115@p14s>
References: <20230323062451.2925996-1-danishanwar@ti.com>
 <20230323062451.2925996-2-danishanwar@ti.com>
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In-Reply-To: <20230323062451.2925996-2-danishanwar@ti.com>
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Hi Danish

On Thu, Mar 23, 2023 at 11:54:47AM +0530, MD Danish Anwar wrote:
> From: Tero Kristo <t-kristo@ti.com>
> 
> Add two new get and put API, pruss_get() and pruss_put() to the
> PRUSS platform driver to allow client drivers to request a handle
> to a PRUSS device. This handle will be used by client drivers to
> request various operations of the PRUSS platform driver through
> additional API that will be added in the following patches.
> 
> The pruss_get() function returns the pruss handle corresponding
> to a PRUSS device referenced by a PRU remoteproc instance. The
> pruss_put() is the complimentary function to pruss_get().
> 
> Co-developed-by: Suman Anna <s-anna@ti.com>
> Signed-off-by: Suman Anna <s-anna@ti.com>
> Signed-off-by: Tero Kristo <t-kristo@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>
> Reviewed-by: Roger Quadros <rogerq@kernel.org>
> ---
>  drivers/remoteproc/pru_rproc.c                |  2 +-
>  drivers/soc/ti/pruss.c                        | 60 ++++++++++++++++++-
>  .../{pruss_driver.h => pruss_internal.h}      |  7 ++-
>  include/linux/remoteproc/pruss.h              | 19 ++++++
>  4 files changed, 83 insertions(+), 5 deletions(-)
>  rename include/linux/{pruss_driver.h => pruss_internal.h} (90%)
> 
> diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
> index b76db7fa693d..4ddd5854d56e 100644
> --- a/drivers/remoteproc/pru_rproc.c
> +++ b/drivers/remoteproc/pru_rproc.c
> @@ -19,7 +19,7 @@
>  #include <linux/of_device.h>
>  #include <linux/of_irq.h>
>  #include <linux/remoteproc/pruss.h>
> -#include <linux/pruss_driver.h>
> +#include <linux/pruss_internal.h>
>  #include <linux/remoteproc.h>
>  
>  #include "remoteproc_internal.h"
> diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
> index 6882c86b3ce5..6c2bb02a521d 100644
> --- a/drivers/soc/ti/pruss.c
> +++ b/drivers/soc/ti/pruss.c
> @@ -6,6 +6,7 @@
>   * Author(s):
>   *	Suman Anna <s-anna@ti.com>
>   *	Andrew F. Davis <afd@ti.com>
> + *	Tero Kristo <t-kristo@ti.com>
>   */
>  
>  #include <linux/clk-provider.h>
> @@ -16,8 +17,9 @@
>  #include <linux/of_address.h>
>  #include <linux/of_device.h>
>  #include <linux/pm_runtime.h>
> -#include <linux/pruss_driver.h>
> +#include <linux/pruss_internal.h>
>  #include <linux/regmap.h>
> +#include <linux/remoteproc.h>
>  #include <linux/slab.h>
>  
>  /**
> @@ -30,6 +32,62 @@ struct pruss_private_data {
>  	bool has_core_mux_clock;
>  };
>  
> +/**
> + * pruss_get() - get the pruss for a given PRU remoteproc
> + * @rproc: remoteproc handle of a PRU instance
> + *
> + * Finds the parent pruss device for a PRU given the @rproc handle of the
> + * PRU remote processor. This function increments the pruss device's refcount,
> + * so always use pruss_put() to decrement it back once pruss isn't needed
> + * anymore.
> + *
> + * Return: pruss handle on success, and an ERR_PTR on failure using one
> + * of the following error values
> + *    -EINVAL if invalid parameter
> + *    -ENODEV if PRU device or PRUSS device is not found
> + */
> +struct pruss *pruss_get(struct rproc *rproc)
> +{
> +	struct pruss *pruss;
> +	struct device *dev;
> +	struct platform_device *ppdev;
> +
> +	if (IS_ERR_OR_NULL(rproc))
> +		return ERR_PTR(-EINVAL);
> +

There is no guarantee that @rproc is valid without calling rproc_get_by_handle()
or pru_rproc_get().

> +	dev = &rproc->dev;
> +
> +	/* make sure it is PRU rproc */
> +	if (!dev->parent || !is_pru_rproc(dev->parent))
> +		return ERR_PTR(-ENODEV);
> +
> +	ppdev = to_platform_device(dev->parent->parent);
> +	pruss = platform_get_drvdata(ppdev);
> +	if (!pruss)
> +		return ERR_PTR(-ENODEV);
> +
> +	get_device(pruss->dev);
> +
> +	return pruss;
> +}
> +EXPORT_SYMBOL_GPL(pruss_get);
> +
> +/**
> + * pruss_put() - decrement pruss device's usecount
> + * @pruss: pruss handle
> + *
> + * Complimentary function for pruss_get(). Needs to be called
> + * after the PRUSS is used, and only if the pruss_get() succeeds.
> + */
> +void pruss_put(struct pruss *pruss)
> +{
> +	if (IS_ERR_OR_NULL(pruss))
> +		return;
> +
> +	put_device(pruss->dev);
> +}
> +EXPORT_SYMBOL_GPL(pruss_put);
> +
>  static void pruss_of_free_clk_provider(void *data)
>  {
>  	struct device_node *clk_mux_np = data;
> diff --git a/include/linux/pruss_driver.h b/include/linux/pruss_internal.h
> similarity index 90%
> rename from include/linux/pruss_driver.h
> rename to include/linux/pruss_internal.h
> index ecfded30ed05..8f91cb164054 100644
> --- a/include/linux/pruss_driver.h
> +++ b/include/linux/pruss_internal.h
> @@ -6,9 +6,10 @@
>   *	Suman Anna <s-anna@ti.com>
>   */
>  
> -#ifndef _PRUSS_DRIVER_H_
> -#define _PRUSS_DRIVER_H_
> +#ifndef _PRUSS_INTERNAL_H_
> +#define _PRUSS_INTERNAL_H_
>  
> +#include <linux/remoteproc/pruss.h>
>  #include <linux/types.h>
>  
>  /*
> @@ -51,4 +52,4 @@ struct pruss {
>  	struct clk *iep_clk_mux;
>  };
>  
> -#endif	/* _PRUSS_DRIVER_H_ */
> +#endif	/* _PRUSS_INTERNAL_H_ */
> diff --git a/include/linux/remoteproc/pruss.h b/include/linux/remoteproc/pruss.h
> index 039b50d58df2..93a98cac7829 100644
> --- a/include/linux/remoteproc/pruss.h
> +++ b/include/linux/remoteproc/pruss.h
> @@ -4,12 +4,14 @@
>   *
>   * Copyright (C) 2015-2022 Texas Instruments Incorporated - http://www.ti.com
>   *	Suman Anna <s-anna@ti.com>
> + *	Tero Kristo <t-kristo@ti.com>
>   */
>  
>  #ifndef __LINUX_PRUSS_H
>  #define __LINUX_PRUSS_H
>  
>  #include <linux/device.h>
> +#include <linux/err.h>
>  #include <linux/types.h>
>  
>  #define PRU_RPROC_DRVNAME "pru-rproc"
> @@ -44,6 +46,23 @@ enum pru_ctable_idx {
>  
>  struct device_node;
>  struct rproc;
> +struct pruss;
> +
> +#if IS_ENABLED(CONFIG_TI_PRUSS)
> +
> +struct pruss *pruss_get(struct rproc *rproc);
> +void pruss_put(struct pruss *pruss);
> +
> +#else
> +
> +static inline struct pruss *pruss_get(struct rproc *rproc)
> +{
> +	return ERR_PTR(-EOPNOTSUPP);
> +}
> +
> +static inline void pruss_put(struct pruss *pruss) { }
> +
> +#endif /* CONFIG_TI_PRUSS */
>  
>  #if IS_ENABLED(CONFIG_PRU_REMOTEPROC)
>  
> -- 
> 2.25.1
>