Re: [RFC PATCH v2 05/12] mtd: rawnand: ams-delta: use GPIO API for data read/write

Marek Vasut
2018-08-06T23:58:44Z

On 08/07/2018 12:29 AM, Janusz Krzysztofik wrote:
> Don't readw()/writew() data directly from/to GPIO port which is under
> control of gpio-omap driver, use GPIO API instead.
>
> Degrade of performance on Amstrad Delta is completely not acceptable.

I'd expect that changing from direct PIO to access through GPIO API
would degrade the performance. Maybe I misunderstood something ?

> The driver should work with any 8+-bit bidirectional GPIO port, not
> only OMAP.
>
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
> ---
> drivers/mtd/nand/raw/ams-delta.c | 97 ++++++++++++++++------------------------
> 1 file changed, 38 insertions(+), 59 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
> index 09d6901fc94d..78996ddf82e0 100644
> --- a/drivers/mtd/nand/raw/ams-delta.c
> +++ b/drivers/mtd/nand/raw/ams-delta.c
> @@ -24,13 +24,10 @@
> #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 <asm/io.h>
> #include <asm/sizes.h>
>
> -#include <mach/hardware.h>
> -
> /*
> * MTD structure for E3 (Delta)
> */
> @@ -44,7 +41,7 @@ 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;
> };
>
> /*
> @@ -76,10 +73,14 @@ static void ams_delta_write_byte(struct mtd_info *mtd, u_char byte)
> {
> struct nand_chip *this = mtd_to_nand(mtd);
> struct ams_delta_nand *priv = nand_get_controller_data(this);
> - void __iomem *io_base = priv->io_base;
> + struct gpio_descs *data_gpiods = priv->data_gpiods;
> + unsigned long bits = byte;
> + int i;
> +
> + for (i = 0; i < data_gpiods->ndescs; i++)
> + gpiod_direction_output_raw(data_gpiods->desc[i],
> + test_bit(i, &bits));
>
> - writew(0, io_base + OMAP_MPUIO_IO_CNTL);
> - writew(byte, this->IO_ADDR_W);
> gpiod_set_value(priv->gpiod_nwe, 0);
> ndelay(40);
> gpiod_set_value(priv->gpiod_nwe, 1);
> @@ -87,18 +88,28 @@ static void ams_delta_write_byte(struct mtd_info *mtd, u_char byte)
>
> static u_char ams_delta_read_byte(struct mtd_info *mtd)
> {
> - u_char res;
> struct nand_chip *this = mtd_to_nand(mtd);
> struct ams_delta_nand *priv = nand_get_controller_data(this);
> - void __iomem *io_base = priv->io_base;
> + struct gpio_descs *data_gpiods = priv->data_gpiods;
> + unsigned long bits = 0;
> + int i, value_array[data_gpiods->ndescs];
> +
> + for (i = 0; i < data_gpiods->ndescs; i++)
> + gpiod_direction_input(data_gpiods->desc[i]);
>
> gpiod_set_value(priv->gpiod_nre, 0);
> ndelay(40);
> - writew(~0, io_base + OMAP_MPUIO_IO_CNTL);
> - res = readw(this->IO_ADDR_R);
> +
> + gpiod_get_raw_array_value(data_gpiods->ndescs, data_gpiods->desc,
> + value_array);
> +
> gpiod_set_value(priv->gpiod_nre, 1);
>
> - return res;
> + for (i = 0; i < data_gpiods->ndescs; i++)
> + if (value_array[i])
> + __set_bit(i, &bits);
> +
> + return bits;
> }
>
> static void ams_delta_write_buf(struct mtd_info *mtd, const u_char *buf,
> @@ -159,14 +170,8 @@ 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);
> @@ -179,25 +184,8 @@ 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 == NULL) {
> - dev_err(&pdev->dev, "ioremap failed\n");
> - err = -EIO;
> - goto out_free;
> - }
> -
> - priv->io_base = io_base;
> nand_set_controller_data(this, priv);
>
> - /* Set address of NAND IO lines */
> - this->IO_ADDR_R = io_base + OMAP_MPUIO_INPUT_LATCH;
> - this->IO_ADDR_W = io_base + OMAP_MPUIO_OUTPUT;
> this->read_byte = ams_delta_read_byte;
> this->write_buf = ams_delta_write_buf;
> this->read_buf = ams_delta_read_buf;
> @@ -207,7 +195,7 @@ static int ams_delta_init(struct platform_device *pdev)
> if (IS_ERR(priv->gpiod_rdy)) {
> err = PTR_ERR(priv->gpiod_rdy);
> dev_warn(&pdev->dev, "RDY GPIO request failed (%d)\n", err);
> - goto out_mtd;
> + return err;
> }
>
> if (priv->gpiod_rdy)
> @@ -225,66 +213,60 @@ 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 out_mtd;
> + 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 out_mtd;
> + 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 out_mtd;
> + 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 out_mtd;
> + 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 out_mtd;
> + 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 out_mtd;
> + return err;
> }
> /* Request array of data pins, initialize them as input */
> - data_gpiods = devm_gpiod_get_array(&pdev->dev, "data", GPIOD_IN);
> - if (IS_ERR(data_gpiods)) {
> - err = PTR_ERR(data_gpiods);
> + priv->data_gpiods = devm_gpiod_get_array(&pdev->dev, "data", GPIOD_IN);
> + if (IS_ERR(priv->data_gpiods)) {
> + err = PTR_ERR(priv->data_gpiods);
> dev_err(&pdev->dev, "data GPIO request failed: %d\n", err);
> - goto out_mtd;
> + return err;
> }
>
> /* Scan to find existence of the device */
> err = nand_scan(mtd, 1);
> if (err)
> - goto out_mtd;
> + return err;
>
> /* Register the partitions */
> mtd_device_register(mtd, partition_info, ARRAY_SIZE(partition_info));
>
> - goto out;
> -
> - out_mtd:
> - iounmap(io_base);
> -out_free:
> - out:
> - return err;
> + return 0;
> }
>
> /*
> @@ -294,13 +276,10 @@ 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);
>
> - iounmap(io_base);
> -
> return 0;
> }
>
>

--
Best regards,
Marek Vasut