Re: [PATCH v4 3/4] mtd: rawnand: ams-delta: Use GPIO API for data I/O

[Boris Brezillon <boris.brezillon@bootlin.com>]

On Wed, 21 Nov 2018 12:08:05 +0100
Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:

> Don't readw()/writew() data directly from/to GPIO port which is under
> control of gpio-omap driver, use GPIO consumer API instead.
> 
> The driver should now work with any 8-bit bidirectional GPIO port, not
> only OMAP.
> 
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

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

And thanks a lot for keeping up with that. I like the new ams-delta
driver, and I wonder if we couldn't extend it to replace the gpio-nand
driver.

> ---
>  drivers/mtd/nand/raw/ams-delta.c | 109 +++++++++++++++++--------------
>  1 file changed, 61 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
> index bb50dda05654..8312182088c1 100644
> --- a/drivers/mtd/nand/raw/ams-delta.c
> +++ b/drivers/mtd/nand/raw/ams-delta.c
> @@ -18,11 +18,10 @@
>  #include <linux/module.h>
>  #include <linux/delay.h>
>  #include <linux/gpio/consumer.h>
> -#include <linux/io.h>
>  #include <linux/mtd/mtd.h>
>  #include <linux/mtd/rawnand.h>
>  #include <linux/mtd/partitions.h>
> -#include <linux/platform_data/gpio-omap.h>
> +#include <linux/platform_device.h>
>  #include <linux/sizes.h>
>  
>  /*
> @@ -38,7 +37,7 @@ struct ams_delta_nand {
>  	struct gpio_desc	*gpiod_nwe;
>  	struct gpio_desc	*gpiod_ale;
>  	struct gpio_desc	*gpiod_cle;
> -	void __iomem		*io_base;
> +	struct gpio_descs	*data_gpiods;
>  	bool			data_in;
>  };
>  
> @@ -67,42 +66,78 @@ static const struct mtd_partition partition_info[] = {
>  	  .size		=  3 * SZ_256K },
>  };
>  
> -static void ams_delta_io_write(struct ams_delta_nand *priv, u8 byte)
> +static void ams_delta_write_commit(struct ams_delta_nand *priv)
>  {
> -	writew(byte, priv->io_base + OMAP_MPUIO_OUTPUT);
>  	gpiod_set_value(priv->gpiod_nwe, 0);
>  	ndelay(40);
>  	gpiod_set_value(priv->gpiod_nwe, 1);
>  }
>  
> +static void ams_delta_io_write(struct ams_delta_nand *priv, u8 byte)
> +{
> +	struct gpio_descs *data_gpiods = priv->data_gpiods;
> +	DECLARE_BITMAP(values, BITS_PER_TYPE(byte)) = { byte, };
> +
> +	gpiod_set_raw_array_value(data_gpiods->ndescs, data_gpiods->desc,
> +				  data_gpiods->info, values);
> +
> +	ams_delta_write_commit(priv);
> +}
> +
> +static void ams_delta_dir_output(struct ams_delta_nand *priv, u8 byte)
> +{
> +	struct gpio_descs *data_gpiods = priv->data_gpiods;
> +	DECLARE_BITMAP(values, BITS_PER_TYPE(byte)) = { byte, };
> +	int i;
> +
> +	for (i = 0; i < data_gpiods->ndescs; i++)
> +		gpiod_direction_output_raw(data_gpiods->desc[i],
> +					   test_bit(i, values));
> +
> +	ams_delta_write_commit(priv);
> +
> +	priv->data_in = false;
> +}
> +
>  static u8 ams_delta_io_read(struct ams_delta_nand *priv)
>  {
>  	u8 res;
> +	struct gpio_descs *data_gpiods = priv->data_gpiods;
> +	DECLARE_BITMAP(values, BITS_PER_TYPE(res)) = { 0, };
>  
>  	gpiod_set_value(priv->gpiod_nre, 0);
>  	ndelay(40);
> -	res = readw(priv->io_base + OMAP_MPUIO_INPUT_LATCH);
> +
> +	gpiod_get_raw_array_value(data_gpiods->ndescs, data_gpiods->desc,
> +				  data_gpiods->info, values);
> +
>  	gpiod_set_value(priv->gpiod_nre, 1);
>  
> +	res = values[0];
>  	return res;
>  }
>  
> -static void ams_delta_dir_input(struct ams_delta_nand *priv, bool in)
> +static void ams_delta_dir_input(struct ams_delta_nand *priv)
>  {
> -	writew(in ? ~0 : 0, priv->io_base + OMAP_MPUIO_IO_CNTL);
> -	priv->data_in = in;
> +	struct gpio_descs *data_gpiods = priv->data_gpiods;
> +	int i;
> +
> +	for (i = 0; i < data_gpiods->ndescs; i++)
> +		gpiod_direction_input(data_gpiods->desc[i]);
> +
> +	priv->data_in = true;
>  }
>  
>  static void ams_delta_write_buf(struct ams_delta_nand *priv, const u8 *buf,
>  				int len)
>  {
> -	int i;
> +	int i = 0;
>  
> -	if (priv->data_in)
> -		ams_delta_dir_input(priv, false);
> +	if (len > 0 && priv->data_in)
> +		ams_delta_dir_output(priv, buf[i++]);
>  
> -	for (i = 0; i < len; i++)
> -		ams_delta_io_write(priv, buf[i]);
> +	while (i < len)
> +		ams_delta_io_write(priv, buf[i++]);
>  }
>  
>  static void ams_delta_read_buf(struct ams_delta_nand *priv, u8 *buf, int len)
> @@ -110,7 +145,7 @@ static void ams_delta_read_buf(struct ams_delta_nand *priv, u8 *buf, int len)
>  	int i;
>  
>  	if (!priv->data_in)
> -		ams_delta_dir_input(priv, true);
> +		ams_delta_dir_input(priv);
>  
>  	for (i = 0; i < len; i++)
>  		buf[i] = ams_delta_io_read(priv);
> @@ -188,14 +223,9 @@ static int ams_delta_init(struct platform_device *pdev)
>  	struct ams_delta_nand *priv;
>  	struct nand_chip *this;
>  	struct mtd_info *mtd;
> -	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	void __iomem *io_base;
>  	struct gpio_descs *data_gpiods;
>  	int err = 0;
>  
> -	if (!res)
> -		return -ENXIO;
> -
>  	/* Allocate memory for MTD device structure and private data */
>  	priv = devm_kzalloc(&pdev->dev, sizeof(struct ams_delta_nand),
>  			    GFP_KERNEL);
> @@ -207,25 +237,13 @@ static int ams_delta_init(struct platform_device *pdev)
>  	mtd = nand_to_mtd(this);
>  	mtd->dev.parent = &pdev->dev;
>  
> -	/*
> -	 * Don't try to request the memory region from here,
> -	 * it should have been already requested from the
> -	 * gpio-omap driver and requesting it again would fail.
> -	 */
> -	io_base = ioremap(res->start, resource_size(res));
> -	if (!io_base) {
> -		dev_err(&pdev->dev, "ioremap failed\n");
> -		return -EIO;
> -	}
> -
> -	priv->io_base = io_base;
>  	nand_set_controller_data(this, priv);
>  
>  	priv->gpiod_rdy = devm_gpiod_get_optional(&pdev->dev, "rdy", GPIOD_IN);
>  	if (IS_ERR(priv->gpiod_rdy)) {
>  		err = PTR_ERR(priv->gpiod_rdy);
>  		dev_warn(&pdev->dev, "RDY GPIO request failed (%d)\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
>  
>  	this->ecc.mode = NAND_ECC_SOFT;
> @@ -238,42 +256,42 @@ static int ams_delta_init(struct platform_device *pdev)
>  	if (IS_ERR(priv->gpiod_nwp)) {
>  		err = PTR_ERR(priv->gpiod_nwp);
>  		dev_err(&pdev->dev, "NWP GPIO request failed (%d)\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
>  
>  	priv->gpiod_nce = devm_gpiod_get(&pdev->dev, "nce", GPIOD_OUT_HIGH);
>  	if (IS_ERR(priv->gpiod_nce)) {
>  		err = PTR_ERR(priv->gpiod_nce);
>  		dev_err(&pdev->dev, "NCE GPIO request failed (%d)\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
>  
>  	priv->gpiod_nre = devm_gpiod_get(&pdev->dev, "nre", GPIOD_OUT_HIGH);
>  	if (IS_ERR(priv->gpiod_nre)) {
>  		err = PTR_ERR(priv->gpiod_nre);
>  		dev_err(&pdev->dev, "NRE GPIO request failed (%d)\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
>  
>  	priv->gpiod_nwe = devm_gpiod_get(&pdev->dev, "nwe", GPIOD_OUT_HIGH);
>  	if (IS_ERR(priv->gpiod_nwe)) {
>  		err = PTR_ERR(priv->gpiod_nwe);
>  		dev_err(&pdev->dev, "NWE GPIO request failed (%d)\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
>  
>  	priv->gpiod_ale = devm_gpiod_get(&pdev->dev, "ale", GPIOD_OUT_LOW);
>  	if (IS_ERR(priv->gpiod_ale)) {
>  		err = PTR_ERR(priv->gpiod_ale);
>  		dev_err(&pdev->dev, "ALE GPIO request failed (%d)\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
>  
>  	priv->gpiod_cle = devm_gpiod_get(&pdev->dev, "cle", GPIOD_OUT_LOW);
>  	if (IS_ERR(priv->gpiod_cle)) {
>  		err = PTR_ERR(priv->gpiod_cle);
>  		dev_err(&pdev->dev, "CLE GPIO request failed (%d)\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
>  
>  	/* Request array of data pins, initialize them as input */
> @@ -281,8 +299,9 @@ static int ams_delta_init(struct platform_device *pdev)
>  	if (IS_ERR(data_gpiods)) {
>  		err = PTR_ERR(data_gpiods);
>  		dev_err(&pdev->dev, "data GPIO request failed: %d\n", err);
> -		goto err_unmap;
> +		return err;
>  	}
> +	priv->data_gpiods = data_gpiods;
>  	priv->data_in = true;
>  
>  	/* Initialize the NAND controller object embedded in ams_delta_nand. */
> @@ -293,7 +312,7 @@ static int ams_delta_init(struct platform_device *pdev)
>  	/* Scan to find existence of the device */
>  	err = nand_scan(this, 1);
>  	if (err)
> -		goto err_unmap;
> +		return err;
>  
>  	/* Register the partitions */
>  	err = mtd_device_register(mtd, partition_info,
> @@ -306,9 +325,6 @@ static int ams_delta_init(struct platform_device *pdev)
>  err_nand_cleanup:
>  	nand_cleanup(this);
>  
> -err_unmap:
> -	iounmap(io_base);
> -
>  	return err;
>  }
>  
> @@ -319,13 +335,10 @@ static int ams_delta_cleanup(struct platform_device *pdev)
>  {
>  	struct ams_delta_nand *priv = platform_get_drvdata(pdev);
>  	struct mtd_info *mtd = nand_to_mtd(&priv->nand_chip);
> -	void __iomem *io_base = priv->io_base;
>  
> -	/* Release resources, unregister device */
> +	/* Unregister device */
>  	nand_release(mtd_to_nand(mtd));
>  
> -	iounmap(io_base);
> -
>  	return 0;
>  }
>