mtd: rawnand: ams-delta: Make the driver custom I/O ready

In order to be merged with "gpio-nand", the driver must support custom
(non-GPIO) I/O accessors.

Allow platforms to omit data GPIO port as well as NWE pin info from
device setup.  For the driver to still work on such platform, custom
I/O accessors as well as a custom probe function which initialises the
driver private structure with those accessors must be added to the
driver.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200212003929.6682-14-jmkrzyszt@gmail.com

diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
index d8eef3dffa66f5226f759ca12ddb84dd44d8f617..5a27170b28085f88681f6fe6da558ecff222c87b 100644 (file)
--- a/drivers/mtd/nand/raw/ams-delta.c
+++ b/drivers/mtd/nand/raw/ams-delta.c
@@ -43,6 +43,9 @@ struct ams_delta_nand {
        bool                    data_in;
        unsigned int            tRP;
        unsigned int            tWP;
+       u8                      (*io_read)(struct ams_delta_nand *this);
+       void                    (*io_write)(struct ams_delta_nand *this,
+                                           u8 byte);
 };
 
 static void ams_delta_write_commit(struct ams_delta_nand *priv)
@@ -116,18 +119,18 @@ static void ams_delta_write_buf(struct ams_delta_nand *priv, const u8 *buf,
                ams_delta_dir_output(priv, buf[i++]);
 
        while (i < len)
-               ams_delta_io_write(priv, buf[i++]);
+               priv->io_write(priv, buf[i++]);
 }
 
 static void ams_delta_read_buf(struct ams_delta_nand *priv, u8 *buf, int len)
 {
        int i;
 
-       if (!priv->data_in)
+       if (priv->data_gpiods && !priv->data_in)
                ams_delta_dir_input(priv);
 
        for (i = 0; i < len; i++)
-               buf[i] = ams_delta_io_read(priv);
+               buf[i] = priv->io_read(priv);
 }
 
 static void ams_delta_ctrl_cs(struct ams_delta_nand *priv, bool assert)
@@ -289,7 +292,8 @@ static int ams_delta_init(struct platform_device *pdev)
                return err;
        }
 
-       priv->gpiod_nwe = devm_gpiod_get(&pdev->dev, "nwe", GPIOD_OUT_LOW);
+       priv->gpiod_nwe = devm_gpiod_get_optional(&pdev->dev, "nwe",
+                                                 GPIOD_OUT_LOW);
        if (IS_ERR(priv->gpiod_nwe)) {
                err = PTR_ERR(priv->gpiod_nwe);
                dev_err(&pdev->dev, "NWE GPIO request failed (%d)\n", err);
@@ -311,13 +315,24 @@ static int ams_delta_init(struct platform_device *pdev)
        }
 
        /* Request array of data pins, initialize them as input */
-       priv->data_gpiods = devm_gpiod_get_array(&pdev->dev, "data", GPIOD_IN);
+       priv->data_gpiods = devm_gpiod_get_array_optional(&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);
                return err;
        }
-       priv->data_in = true;
+       if (priv->data_gpiods) {
+               if (!priv->gpiod_nwe) {
+                       dev_err(&pdev->dev,
+                               "mandatory NWE pin not provided by platform\n");
+                       return -ENODEV;
+               }
+
+               priv->io_read = ams_delta_io_read;
+               priv->io_write = ams_delta_io_write;
+               priv->data_in = true;
+       }
 
        if (pdev->id_entry)
                probe = (void *) pdev->id_entry->driver_data;
@@ -328,6 +343,11 @@ static int ams_delta_init(struct platform_device *pdev)
        if (err)
                return err;
 
+       if (!priv->io_read || !priv->io_write) {
+               dev_err(&pdev->dev, "incomplete device configuration\n");
+               return -ENODEV;
+       }
+
        /* Initialize the NAND controller object embedded in ams_delta_nand. */
        priv->base.ops = &ams_delta_ops;
        nand_controller_init(&priv->base);