Create an interface independent layer for the probe function. This is to
make it possible to add support for other interfaces.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
---
 drivers/gpu/drm/sitronix/st7571-i2c.c | 165 +++++++++++++++++++++++-----------
 drivers/gpu/drm/sitronix/st7571.h     |  25 +-----
 2 files changed, 113 insertions(+), 77 deletions(-)

diff --git a/drivers/gpu/drm/sitronix/st7571-i2c.c b/drivers/gpu/drm/sitronix/st7571-i2c.c
index af27658a5e15..f994ace40739 100644
--- a/drivers/gpu/drm/sitronix/st7571-i2c.c
+++ b/drivers/gpu/drm/sitronix/st7571-i2c.c
@@ -80,6 +80,33 @@
 #define DRIVER_MAJOR 1
 #define DRIVER_MINOR 0
 
+struct st7571_i2c_transport {
+	struct i2c_client *client;
+
+	/*
+	 * Depending on the hardware design, the acknowledge signal may be hard to
+	 * recognize as a valid logic "0" level.
+	 * Therefor, ignore NAK if possible to stay compatible with most hardware designs
+	 * and off-the-shelf panels out there.
+	 *
+	 * From section 6.4 MICROPOCESSOR INTERFACE section in the datasheet:
+	 *
+	 * "By connecting SDA_OUT to SDA_IN externally, the SDA line becomes fully
+	 * I2C interface compatible.
+	 * Separating acknowledge-output from serial data
+	 * input is advantageous for chip-on-glass (COG) applications. In COG
+	 * applications, the ITO resistance and the pull-up resistor will form a
+	 * voltage  divider, which affects acknowledge-signal level. Larger ITO
+	 * resistance will raise the acknowledged-signal level and system cannot
+	 * recognize this level as a valid logic “0” level. By separating SDA_IN from
+	 * SDA_OUT, the IC can be used in a mode that ignores the acknowledge-bit.
+	 * For applications which check acknowledge-bit, it is necessary to minimize
+	 * the ITO resistance of the SDA_OUT trace to guarantee a valid low level."
+	 *
+	 */
+	bool ignore_nak;
+};
+
 static inline struct st7571_device *drm_to_st7571(struct drm_device *drm)
 {
 	return container_of(drm, struct st7571_device, drm);
@@ -87,18 +114,17 @@ static inline struct st7571_device *drm_to_st7571(struct drm_device *drm)
 
 static int st7571_regmap_write(void *context, const void *data, size_t count)
 {
-	struct i2c_client *client = context;
-	struct st7571_device *st7571 = i2c_get_clientdata(client);
+	struct st7571_i2c_transport *t = context;
 	int ret;
 
 	struct i2c_msg msg = {
-		.addr = st7571->client->addr,
-		.flags = st7571->ignore_nak ? I2C_M_IGNORE_NAK : 0,
+		.addr = t->client->addr,
+		.flags = t->ignore_nak ? I2C_M_IGNORE_NAK : 0,
 		.len = count,
 		.buf = (u8 *)data
 	};
 
-	ret = i2c_transfer(st7571->client->adapter, &msg, 1);
+	ret = i2c_transfer(t->client->adapter, &msg, 1);
 
 	/*
 	 * Unfortunately, there is no way to check if the transfer failed because of
@@ -106,7 +132,7 @@ static int st7571_regmap_write(void *context, const void *data, size_t count)
 	 *
 	 * However, if the transfer fails and ignore_nak is set, we know it is an error.
 	 */
-	if (ret < 0 && st7571->ignore_nak)
+	if (ret < 0 && t->ignore_nak)
 		return ret;
 
 	return 0;
@@ -845,102 +871,135 @@ static int st7571_lcd_init(struct st7571_device *st7571)
 	return st7571_send_command_list(st7571, commands, ARRAY_SIZE(commands));
 }
 
-static int st7571_probe(struct i2c_client *client)
+static struct st7571_device *st7571_probe(struct device *dev,
+					  struct regmap *regmap)
 {
 	struct st7571_device *st7571;
 	struct drm_device *drm;
 	int ret;
 
-	st7571 = devm_drm_dev_alloc(&client->dev, &st7571_driver,
+	st7571 = devm_drm_dev_alloc(dev, &st7571_driver,
 				    struct st7571_device, drm);
 	if (IS_ERR(st7571))
-		return PTR_ERR(st7571);
+		return st7571;
 
 	drm = &st7571->drm;
-	st7571->dev = &client->dev;
-	st7571->client = client;
-	i2c_set_clientdata(client, st7571);
+	st7571->dev = dev;
 	st7571->pdata = device_get_match_data(st7571->dev);
 
 	ret = st7571->pdata->parse_dt(st7571);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 
 	ret = st7571_validate_parameters(st7571);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 
 	st7571->mode = st7571_mode(st7571);
+	st7571->regmap = regmap;
 
-	/*
-	 * The hardware design could make it hard to detect a NAK on the I2C bus.
-	 * If the adapter does not support protocol mangling do
-	 * not set the I2C_M_IGNORE_NAK flag at the expense * of possible
-	 * cruft in the logs.
-	 */
-	if (i2c_check_functionality(client->adapter, I2C_FUNC_PROTOCOL_MANGLING))
-		st7571->ignore_nak = true;
-
-	st7571->regmap = devm_regmap_init(st7571->dev, &st7571_regmap_bus,
-					  client, &st7571_regmap_config);
-	if (IS_ERR(st7571->regmap)) {
-		return dev_err_probe(st7571->dev, PTR_ERR(st7571->regmap),
-				     "Failed to initialize regmap\n");
-	}
 
 	st7571->hwbuf = devm_kzalloc(st7571->dev,
 				     (st7571->nlines * st7571->ncols * st7571->bpp) / 8,
 				     GFP_KERNEL);
 	if (!st7571->hwbuf)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	st7571->row = devm_kzalloc(st7571->dev,
 				   (st7571->ncols * st7571->bpp),
 				   GFP_KERNEL);
 	if (!st7571->row)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	ret = st7571_mode_config_init(st7571);
-	if (ret)
-		return dev_err_probe(st7571->dev, ret,
-				     "Failed to initialize mode config\n");
+	if (ret) {
+		dev_err(st7571->dev, "Failed to initialize mode config\n");
+		return ERR_PTR(ret);
+	}
 
 	ret = st7571_plane_init(st7571, st7571->pformat);
-	if (ret)
-		return dev_err_probe(st7571->dev, ret,
-				     "Failed to initialize primary plane\n");
+	if (ret) {
+		dev_err(st7571->dev, "Failed to initialize primary plane\n");
+		return ERR_PTR(ret);
+	}
 
 	ret = st7571_crtc_init(st7571);
-	if (ret < 0)
-		return dev_err_probe(st7571->dev, ret,
-				     "Failed to initialize CRTC\n");
+	if (ret < 0) {
+		dev_err(st7571->dev, "Failed to initialize CRTC\n");
+		return ERR_PTR(ret);
+	}
 
 	ret = st7571_encoder_init(st7571);
-	if (ret < 0)
-		return dev_err_probe(st7571->dev, ret,
-				     "Failed to initialize encoder\n");
+	if (ret < 0) {
+		dev_err(st7571->dev, "Failed to initialize encoder\n");
+		return ERR_PTR(ret);
+	}
 
 	ret = st7571_connector_init(st7571);
-	if (ret < 0)
-		return dev_err_probe(st7571->dev, ret,
-				     "Failed to initialize connector\n");
+	if (ret < 0) {
+		dev_err(st7571->dev, "Failed to initialize connector\n");
+		return ERR_PTR(ret);
+	}
 
 	drm_mode_config_reset(drm);
 
 	ret = drm_dev_register(drm, 0);
-	if (ret)
-		return dev_err_probe(st7571->dev, ret,
-				     "Failed to register DRM device\n");
+	if (ret) {
+		dev_err(st7571->dev, "Failed to register DRM device\n");
+		return ERR_PTR(ret);
+	}
 
 	drm_client_setup(drm, NULL);
+	return st7571;
+}
+
+static void st7571_remove(struct st7571_device *st7571)
+{
+	drm_dev_unplug(&st7571->drm);
+}
+
+static int st7571_i2c_probe(struct i2c_client *client)
+{
+	struct st7571_device *st7571;
+	struct st7571_i2c_transport *t;
+	struct regmap *regmap;
+
+	t = devm_kzalloc(&client->dev, sizeof(*t), GFP_KERNEL);
+	if (!t)
+		return -ENOMEM;
+
+	t->client = client;
+
+	/*
+	 * The hardware design could make it hard to detect a NAK on the I2C bus.
+	 * If the adapter does not support protocol mangling do
+	 * not set the I2C_M_IGNORE_NAK flag at the expense * of possible
+	 * cruft in the logs.
+	 */
+	if (i2c_check_functionality(client->adapter, I2C_FUNC_PROTOCOL_MANGLING))
+		t->ignore_nak = true;
+
+	regmap = devm_regmap_init(&client->dev, &st7571_regmap_bus,
+				  t, &st7571_regmap_config);
+	if (IS_ERR(regmap)) {
+		return dev_err_probe(&client->dev, PTR_ERR(regmap),
+				     "Failed to initialize regmap\n");
+	}
+
+	st7571 = st7571_probe(&client->dev, regmap);
+	if (IS_ERR(st7571))
+		return dev_err_probe(&client->dev, PTR_ERR(st7571),
+				     "Failed to initialize regmap\n");
+
+	i2c_set_clientdata(client, st7571);
 	return 0;
 }
 
-static void st7571_remove(struct i2c_client *client)
+static void st7571_i2c_remove(struct i2c_client *client)
 {
 	struct st7571_device *st7571 = i2c_get_clientdata(client);
 
-	drm_dev_unplug(&st7571->drm);
+	st7571_remove(st7571);
 }
 
 static const struct st7571_panel_data st7567_config = {
@@ -986,8 +1045,8 @@ static struct i2c_driver st7571_i2c_driver = {
 		.name = "st7571",
 		.of_match_table = st7571_of_match,
 	},
-	.probe = st7571_probe,
-	.remove = st7571_remove,
+	.probe = st7571_i2c_probe,
+	.remove = st7571_i2c_remove,
 	.id_table = st7571_id,
 };
 
diff --git a/drivers/gpu/drm/sitronix/st7571.h b/drivers/gpu/drm/sitronix/st7571.h
index c6fd6f1d3aa3..f62c57ddb99e 100644
--- a/drivers/gpu/drm/sitronix/st7571.h
+++ b/drivers/gpu/drm/sitronix/st7571.h
@@ -13,6 +13,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_encoder.h>
+#include <drm/drm_format_helper.h>
 
 #include <linux/regmap.h>
 
@@ -62,33 +63,9 @@ struct st7571_device {
 
 	const struct st7571_panel_format *pformat;
 	const struct st7571_panel_data *pdata;
-	struct i2c_client *client;
 	struct gpio_desc *reset;
 	struct regmap *regmap;
 
-	/*
-	 * Depending on the hardware design, the acknowledge signal may be hard to
-	 * recognize as a valid logic "0" level.
-	 * Therefor, ignore NAK if possible to stay compatible with most hardware designs
-	 * and off-the-shelf panels out there.
-	 *
-	 * From section 6.4 MICROPOCESSOR INTERFACE section in the datasheet:
-	 *
-	 * "By connecting SDA_OUT to SDA_IN externally, the SDA line becomes fully
-	 * I2C interface compatible.
-	 * Separating acknowledge-output from serial data
-	 * input is advantageous for chip-on-glass (COG) applications. In COG
-	 * applications, the ITO resistance and the pull-up resistor will form a
-	 * voltage  divider, which affects acknowledge-signal level. Larger ITO
-	 * resistance will raise the acknowledged-signal level and system cannot
-	 * recognize this level as a valid logic “0” level. By separating SDA_IN from
-	 * SDA_OUT, the IC can be used in a mode that ignores the acknowledge-bit.
-	 * For applications which check acknowledge-bit, it is necessary to minimize
-	 * the ITO resistance of the SDA_OUT trace to guarantee a valid low level."
-	 *
-	 */
-	bool ignore_nak;
-
 	bool grayscale;
 	bool inverted;
 	u32 height_mm;

-- 
2.51.2