[RFC PATCH 8/8] mtd: rawnand: ams-delta: Use GPIO callbacks for data I/O

Janusz Krzysztofik
2018-07-18T23:57:07Z

Don't readw()/writew() data directly from/to GPIO port which is under
control of gpio-omap driver, use GPIO chip callbacks instead.

Thanks to utilization of get/set_multiple() callbacks, performance
degrade is minor for typical data transfers.

The driver should now work with any 8+-bit bidirectional GPIO port,
not only OMAP.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>

# Conflicts:
# drivers/mtd/nand/raw/ams-delta.c
---
arch/arm/mach-omap1/board-ams-delta.c | 11 ----
drivers/mtd/nand/raw/ams-delta.c | 119 +++++++++++++++-------------------
2 files changed, 52 insertions(+), 78 deletions(-)

diff --git a/arch/arm/mach-omap1/board-ams-delta.c b/arch/arm/mach-omap1/board-ams-delta.c
index 16f7bbe47607..08e732bc1cd2 100644
--- a/arch/arm/mach-omap1/board-ams-delta.c
+++ b/arch/arm/mach-omap1/board-ams-delta.c
@@ -321,20 +321,9 @@ struct modem_private_data {

static struct modem_private_data modem_priv;

-static struct resource ams_delta_nand_resources[] = {
- [0] = {
- .start = OMAP1_MPUIO_BASE,
- .end = OMAP1_MPUIO_BASE +
- OMAP_MPUIO_IO_CNTL + sizeof(u32) - 1,
- .flags = IORESOURCE_MEM,
- },
-};
-
static struct platform_device ams_delta_nand_device = {
.name = "ams-delta-nand",
.id = -1,
- .num_resources = ARRAY_SIZE(ams_delta_nand_resources),
- .resource = ams_delta_nand_resources,
};

#define OMAP_GPIO_LABEL "gpio-0-15"
diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
index bd501f385e78..8fac8d2a444a 100644
--- a/drivers/mtd/nand/raw/ams-delta.c
+++ b/drivers/mtd/nand/raw/ams-delta.c
@@ -25,13 +25,11 @@
#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)
*/
@@ -45,7 +43,9 @@ 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_chip *data_gpioc;
+ unsigned long data_mask;
+ int data_width;
};

/*
@@ -73,43 +73,55 @@ static const struct mtd_partition partition_info[] = {
.size = 3 * SZ_256K },
};

-static void ams_delta_write_next_byte(struct ams_delta_nand *priv, u_char byte)
+static void ams_delta_write_commit(struct ams_delta_nand *priv)
{
- struct nand_chip *this = &priv->nand_chip;
-
- writew(byte, this->IO_ADDR_W);
gpiod_set_value(priv->gpiod_nwe, 0);
ndelay(40);
gpiod_set_value(priv->gpiod_nwe, 1);
}

+static void ams_delta_write_next_byte(struct ams_delta_nand *priv, u_char byte)
+{
+ struct gpio_chip *data_gpioc = priv->data_gpioc;
+ unsigned long bits = byte;
+
+ data_gpioc->set_multiple(data_gpioc, &priv->data_mask, &bits);
+
+ ams_delta_write_commit(priv);
+}
+
static void ams_delta_write_first_byte(struct ams_delta_nand *priv, u_char byte)
{
- void __iomem *io_base = priv->io_base;
+ struct gpio_chip *data_gpioc = priv->data_gpioc;
+ unsigned long bits = byte;
+ int i;

- writew(0, io_base + OMAP_MPUIO_IO_CNTL);
+ for (i = 0; i < priv->data_width; i++)
+ data_gpioc->direction_output(data_gpioc, i, test_bit(i, &bits));

- ams_delta_write_next_byte(priv, byte);
+ ams_delta_write_commit(priv);
}

static u_char ams_delta_read_next_byte(struct ams_delta_nand *priv)
{
- struct nand_chip *this = &priv->nand_chip;
- u_char res;
+ struct gpio_chip *data_gpioc = priv->data_gpioc;
+ unsigned long bits;

gpiod_set_value(priv->gpiod_nre, 0);
ndelay(40);
- res = readw(this->IO_ADDR_R);
+ data_gpioc->get_multiple(data_gpioc, &priv->data_mask, &bits);
gpiod_set_value(priv->gpiod_nre, 1);

- return res;
+ return bits;
}

static u_char ams_delta_read_first_byte(struct ams_delta_nand *priv)
{
- void __iomem *io_base = priv->io_base;
+ struct gpio_chip *data_gpioc = priv->data_gpioc;
+ int i;

- writew(~0, io_base + OMAP_MPUIO_IO_CNTL);
+ for (i = 0; i < priv->data_width; i++)
+ data_gpioc->direction_input(data_gpioc, i);

return ams_delta_read_next_byte(priv);
}
@@ -188,16 +200,11 @@ 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;
struct gpio_chip *data_gpioc;
unsigned long mask, bits;
int i, 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);
@@ -210,25 +217,8 @@ 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;
@@ -238,7 +228,7 @@ 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)
@@ -256,49 +246,49 @@ 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 output and set low */
data_gpiods = devm_gpiod_get_array(&pdev->dev, "data", GPIOD_OUT_LOW);
if (IS_ERR(data_gpiods)) {
err = PTR_ERR(data_gpiods);
dev_err(&pdev->dev, "data GPIO request failed: %d\n", err);
- goto out_mtd;
+ return err;
}

/* Use GPIO chip of first data GPIO pin descriptor */
@@ -312,7 +302,7 @@ static int ams_delta_init(struct platform_device *pdev)
err = -EINVAL;
dev_err(&pdev->dev,
"data GPIO chip does not support get/set_multiple()\n");
- goto out_mtd;
+ return err;
}

/* Verify if get_multiple() returns all pins low as initialized above */
@@ -321,13 +311,13 @@ static int ams_delta_init(struct platform_device *pdev)
if (err) {
dev_err(&pdev->dev,
"data GPIO chip get_multiple() failed: %d\n", err);
- goto out_mtd;
+ return err;
}
if (bits) {
err = -EINVAL;
dev_err(&pdev->dev,
"mismmatch of data GPIO initial value: %lu\n", bits);
- goto out_mtd;
+ return err;
}

/* Verify each data GPIO pin */
@@ -337,7 +327,7 @@ static int ams_delta_init(struct platform_device *pdev)
err = -EINVAL;
dev_err(&pdev->dev, "GPIO chip mismatch of data bit %d\n",
i);
- goto out_mtd;
+ return err;
}

/* Require all pins active high (not inverted) */
@@ -346,7 +336,7 @@ static int ams_delta_init(struct platform_device *pdev)
dev_err(&pdev->dev,
"unsupported polarity of data GPIO bit %d\n",
i);
- goto out_mtd;
+ return err;
}

/*
@@ -360,13 +350,13 @@ static int ams_delta_init(struct platform_device *pdev)
dev_err(&pdev->dev,
"data bit %d GPIO chip get() failed: %d\n", i,
err);
- goto out_mtd;
+ return err;
}
if (!err) {
err = -EINVAL;
dev_err(&pdev->dev, "mismatch of data GPIO bit %d value\n",
i);
- goto out_mtd;
+ return err;
}

/*
@@ -379,14 +369,18 @@ static int ams_delta_init(struct platform_device *pdev)
dev_err(&pdev->dev,
"unsupported mode of data GPIO bit %d\n",
i);
- goto out_mtd;
+ return err;
}
}

+ priv->data_gpioc = data_gpioc;
+ priv->data_width = data_gpiods->ndescs;
+ priv->data_mask = (1 << data_gpiods->ndescs) - 1;
+
/* Scan to find existence of the device */
err = nand_scan(mtd, 1);
if (err)
- goto out_mtd;
+ return err;

/* As soon as the device is found, release write protection */
gpiod_set_value(priv->gpiod_nwp, 1);
@@ -394,13 +388,7 @@ static int ams_delta_init(struct platform_device *pdev)
/* 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;
}

/*
@@ -410,16 +398,13 @@ 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;

/* Apply write protection */
gpiod_set_value(priv->gpiod_nwp, 0);

- /* Release resources, unregister device */
+ /* Unregister device */
nand_release(mtd);

- iounmap(io_base);
-
return 0;
}

--
2.16.4