linux-kernel - Re: [PATCH v3 2/3] spi: spi-mem: Extend the SPI mem interface to set a custom memory name

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Date:   Thu, 2 Aug 2018 15:12:36 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Frieder Schrempf <frieder.schrempf@...eet.de>
Cc:     dwmw2@...radead.org, computersforpeace@...il.com,
        marek.vasut@...il.com, richard@....at, broonie@...nel.org,
        linux-mtd@...ts.infradead.org, linux-spi@...r.kernel.org,
        cyrille.pitchen@...ev4u.fr, pp@...ix.com, Zhiqiang.Hou@....com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/3] spi: spi-mem: Extend the SPI mem interface to
 set a custom memory name

On Thu,  2 Aug 2018 14:53:53 +0200
Frieder Schrempf <frieder.schrempf@...eet.de> wrote:

> When porting (Q)SPI controller drivers from the MTD layer to the SPI
> layer, the naming scheme for the memory devices changes. To be able
> to keep compatibility with the old drivers naming scheme, a name
> field is added to struct spi_mem and a hook is added to let controller
> drivers set a custom name for the memory device.
> 
> Example for the FSL QSPI driver:
> 
> Name with the old driver: 21e0000.qspi,
> or with multiple devices: 21e0000.qspi-0, 21e0000.qspi-1, ...
> 
> Name with the new driver without spi_mem_get_name: spi4.0
> 
> Suggested-by: Boris Brezillon <boris.brezillon@...tlin.com>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@...eet.de>

Reviewed-by: Boris Brezillon <boris.brezillon@...tlin.com>

> ---
>  drivers/spi/spi-mem.c       | 28 ++++++++++++++++++++++++++++
>  include/linux/spi/spi-mem.h | 12 ++++++++++++
>  2 files changed, 40 insertions(+)
> 
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index 990770d..e43842c 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -311,6 +311,24 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
>  EXPORT_SYMBOL_GPL(spi_mem_exec_op);
>  
>  /**
> + * spi_mem_get_name() - Return the SPI mem device name to be used by the
> + *			upper layer if necessary
> + * @mem: the SPI memory
> + *
> + * This function allows SPI mem users to retrieve the SPI mem device name.
> + * It is useful if the upper layer needs to expose a custom name for
> + * compatibility reasons.
> + *
> + * Return: a string containing the name of the memory device to be used
> + *	   by the SPI mem user
> + */
> +const char *spi_mem_get_name(struct spi_mem *mem)
> +{
> +	return mem->name;
> +}
> +EXPORT_SYMBOL_GPL(spi_mem_get_name);
> +
> +/**
>   * spi_mem_adjust_op_size() - Adjust the data size of a SPI mem operation to
>   *			      match controller limitations
>   * @mem: the SPI memory
> @@ -344,6 +362,7 @@ static inline struct spi_mem_driver *to_spi_mem_drv(struct device_driver *drv)
>  static int spi_mem_probe(struct spi_device *spi)
>  {
>  	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
> +	struct spi_controller *ctlr = spi->controller;
>  	struct spi_mem *mem;
>  
>  	mem = devm_kzalloc(&spi->dev, sizeof(*mem), GFP_KERNEL);
> @@ -351,6 +370,15 @@ static int spi_mem_probe(struct spi_device *spi)
>  		return -ENOMEM;
>  
>  	mem->spi = spi;
> +
> +	if (ctlr->mem_ops && ctlr->mem_ops->get_name)
> +		mem->name = ctlr->mem_ops->get_name(mem);
> +	else
> +		mem->name = dev_name(&spi->dev);
> +
> +	if (IS_ERR_OR_NULL(mem->name))
> +		return PTR_ERR(mem->name);
> +
>  	spi_set_drvdata(spi, mem);
>  
>  	return memdrv->probe(mem);
> diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
> index 72cc9bc..0d41826 100644
> --- a/include/linux/spi/spi-mem.h
> +++ b/include/linux/spi/spi-mem.h
> @@ -125,6 +125,7 @@ struct spi_mem_op {
>   * struct spi_mem - describes a SPI memory device
>   * @spi: the underlying SPI device
>   * @drvpriv: spi_mem_driver private data
> + * @name: name of the SPI memory device
>   *
>   * Extra information that describe the SPI memory device and may be needed by
>   * the controller to properly handle this device should be placed here.
> @@ -135,6 +136,7 @@ struct spi_mem_op {
>  struct spi_mem {
>  	struct spi_device *spi;
>  	void *drvpriv;
> +	char *name;
>  };
>  
>  /**
> @@ -167,6 +169,13 @@ static inline void *spi_mem_get_drvdata(struct spi_mem *mem)
>   *		    limitations)
>   * @supports_op: check if an operation is supported by the controller
>   * @exec_op: execute a SPI memory operation
> + * @get_name: get a custom name for the SPI mem device from the controller.
> + *	      This might be needed if the controller driver has been ported
> + *	      to use the SPI mem layer and a custom name is used to keep
> + *	      mtdparts compatible.
> + *	      Note that if the implementation of this function allocates memory
> + *	      dynamically, then it should do so with devm_xxx(), as we don't
> + *	      have a ->free_name() function.
>   *
>   * This interface should be implemented by SPI controllers providing an
>   * high-level interface to execute SPI memory operation, which is usually the
> @@ -178,6 +187,7 @@ struct spi_controller_mem_ops {
>  			    const struct spi_mem_op *op);
>  	int (*exec_op)(struct spi_mem *mem,
>  		       const struct spi_mem_op *op);
> +	const char *(*get_name)(struct spi_mem *mem);
>  };
>  
>  /**
> @@ -236,6 +246,8 @@ bool spi_mem_supports_op(struct spi_mem *mem,
>  int spi_mem_exec_op(struct spi_mem *mem,
>  		    const struct spi_mem_op *op);
>  
> +const char *spi_mem_get_name(struct spi_mem *mem);
> +
>  int spi_mem_driver_register_with_owner(struct spi_mem_driver *drv,
>  				       struct module *owner);
>