linux-kernel - Re: [PATCH v5 17/26] mtd: nand: omap2: Implement NAND ready using gpiolib

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Message-ID: <20160305014624.GK55664@google.com>
Date:	Fri, 4 Mar 2016 17:46:24 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	Roger Quadros <rogerq@...com>
Cc:	tony@...mide.com, dwmw2@...radead.org,
	ezequiel@...guardiasur.com.ar, javier@...hile0.org, fcooper@...com,
	nsekhar@...com, linux-mtd@...ts.infradead.org,
	linux-omap@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 17/26] mtd: nand: omap2: Implement NAND ready using
 gpiolib

+ Boris

On Fri, Feb 19, 2016 at 11:15:39PM +0200, Roger Quadros wrote:
> The GPMC WAIT pin status are now available over gpiolib.
> Update the omap_dev_ready() function to use gpio instead of
> directly accessing GPMC register space.
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  .../devicetree/bindings/mtd/gpmc-nand.txt          |  2 ++
>  drivers/mtd/nand/omap2.c                           | 29 ++++++++++++++--------
>  include/linux/platform_data/mtd-nand-omap2.h       |  2 +-
>  3 files changed, 21 insertions(+), 12 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> index 810b87b..256bb86 100644
> --- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> @@ -48,6 +48,7 @@ Optional properties:
>  		locating ECC errors for BCHx algorithms. SoC devices which have
>  		ELM hardware engines should specify this device node in .dtsi
>  		Using ELM for ECC error correction frees some CPU cycles.
> + - rb-gpios:	GPIO specifier for the ready/busy# pin.

^^ Looks better, I think.

Brian

>  
>  For inline partition table parsing (optional):
>  
> @@ -78,6 +79,7 @@ Example for an AM33xx board:
>  			ti,nand-xfer-type = "polled";
>  			interrupt-parent = <&gpmc>;
>  			interrupts = <0>, <1>;
> +			rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>; /* gpmc_wait0 */
>  
>  			gpmc,sync-clk-ps = <0>;
>  			gpmc,cs-on-ns = <0>;
> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
> index 0a637c4..e7939f1 100644
> --- a/drivers/mtd/nand/omap2.c
> +++ b/drivers/mtd/nand/omap2.c
> @@ -12,6 +12,7 @@
>  #include <linux/dmaengine.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/module.h>
>  #include <linux/interrupt.h>
>  #include <linux/jiffies.h>
> @@ -183,6 +184,8 @@ struct omap_nand_info {
>  	struct nand_ecclayout		oobinfo;
>  	/* fields specific for BCHx_HW ECC scheme */
>  	struct device			*elm_dev;
> +	/* NAND ready gpio */
> +	struct gpio_desc		*ready_gpiod;
>  };
>  
>  static inline struct omap_nand_info *mtd_to_omap(struct mtd_info *mtd)
> @@ -1024,21 +1027,16 @@ static int omap_wait(struct mtd_info *mtd, struct nand_chip *chip)
>  }
>  
>  /**
> - * omap_dev_ready - calls the platform specific dev_ready function
> + * omap_dev_ready - checks the NAND Ready GPIO line
>   * @mtd: MTD device structure
> + *
> + * Returns true if ready and false if busy.
>   */
>  static int omap_dev_ready(struct mtd_info *mtd)
>  {
> -	unsigned int val = 0;
>  	struct omap_nand_info *info = mtd_to_omap(mtd);
>  
> -	val = readl(info->reg.gpmc_status);
> -
> -	if ((val & 0x100) == 0x100) {
> -		return 1;
> -	} else {
> -		return 0;
> -	}
> +	return gpiod_get_value(info->ready_gpiod);
>  }
>  
>  /**
> @@ -1754,7 +1752,9 @@ static int omap_nand_probe(struct platform_device *pdev)
>  		info->gpmc_cs = pdata->cs;
>  		info->reg = pdata->reg;
>  		info->ecc_opt = pdata->ecc_opt;
> -		info->dev_ready	= pdata->dev_ready;
> +		if (pdata->dev_ready)
> +			dev_info(&pdev->dev, "pdata->dev_ready is deprecated\n");
> +
>  		info->xfer_type = pdata->xfer_type;
>  		info->devsize = pdata->devsize;
>  		info->elm_of_node = pdata->elm_of_node;
> @@ -1786,6 +1786,13 @@ static int omap_nand_probe(struct platform_device *pdev)
>  	nand_chip->IO_ADDR_W = nand_chip->IO_ADDR_R;
>  	nand_chip->cmd_ctrl  = omap_hwcontrol;
>  
> +	info->ready_gpiod = devm_gpiod_get_optional(&pdev->dev, "rb",
> +						    GPIOD_IN);
> +	if (IS_ERR(info->ready_gpiod)) {
> +		dev_err(dev, "failed to get ready gpio\n");
> +		return PTR_ERR(info->ready_gpiod);
> +	}
> +
>  	/*
>  	 * If RDY/BSY line is connected to OMAP then use the omap ready
>  	 * function and the generic nand_wait function which reads the status
> @@ -1793,7 +1800,7 @@ static int omap_nand_probe(struct platform_device *pdev)
>  	 * chip delay which is slightly more than tR (AC Timing) of the NAND
>  	 * device and read status register until you get a failure or success
>  	 */
> -	if (info->dev_ready) {
> +	if (info->ready_gpiod) {
>  		nand_chip->dev_ready = omap_dev_ready;
>  		nand_chip->chip_delay = 0;
>  	} else {
> diff --git a/include/linux/platform_data/mtd-nand-omap2.h b/include/linux/platform_data/mtd-nand-omap2.h
> index 7f6de53..17d57a1 100644
> --- a/include/linux/platform_data/mtd-nand-omap2.h
> +++ b/include/linux/platform_data/mtd-nand-omap2.h
> @@ -71,7 +71,6 @@ struct omap_nand_platform_data {
>  	int			cs;
>  	struct mtd_partition	*parts;
>  	int			nr_parts;
> -	bool			dev_ready;
>  	bool			flash_bbt;
>  	enum nand_io		xfer_type;
>  	int			devsize;
> @@ -82,5 +81,6 @@ struct omap_nand_platform_data {
>  	/* deprecated */
>  	struct gpmc_nand_regs	reg;
>  	struct device_node	*of_node;
> +	bool			dev_ready;
>  };
>  #endif
> -- 
> 2.1.4
>