[PATCH v3 0/5] drm/solomon: Add SSD130x OLED displays SPI support

[PATCH v3 0/5] drm/solomon: Add SSD130x OLED displays SPI support

[Javier Martinez Canillas]

Hello,

This series adds a ssd130x-spi driver that provides a 4-wire SPI transport
support for SSD130x OLED controllers that can be accessed over a SPI bus.

The driver is quite similar to existing ssd130x-i2c driver that is used by
I2C controllers, but there is a difference in the protocol used by SSD130x
depending on the transport used. The details are in patch #4 description.

Patch #1 just makes the current ssd130x-i2c compatible strings in the DT
binding to be deprecated, and add new ones that don't have an "fb-i2c".

Patch #2 extends the DT binding with the properties needed to support SPI.

Patch #3 adds the new compatible strings to the OF device ID table in the
ssd130x-i2c DRM driver and deprecate the old ones.

Patch #4 moves the device info for the different SSD130x variants from
the ssd130x-i2c transport driver to the ssd130x core driver.

Finally patch #5 adds the ssd130x-spi DRM driver for the OLED controllers
that come with a 4-wire SPI interface, instead of an I2C interface.

This is a v3 that addresses the issues pointed out in v2.

Best regards,
Javier

Changes in v3:
- Drop the "sinowealth,sh1106-i2c", wasn't in a released version (Chen-Yu Tsai)
- Continue enforcing required properties for deprecated strings (Maxime Ripard)
- Add a comment to the properties required for SPI (Geert Uytterhoeven)
- Drop the "sinowealth,sh1106-i2c", wasn't in a released version (Chen-Yu Tsai)
- s/it/they in the commit description (Geert Uytterhoeven)
- Drop unnecessary blank line (Geert Uytterhoeven)
- Export variants array and use &info[ID] in device table (Andy Shevchenko)
- Drop ssd130x_spi_get_dc() helper and open code it (Geert Uytterhoeven)
- Export variants array and use &info[ID] in device table (Andy Shevchenko)
- Add Geert Uytterhoeven's Reviewed-by tag to patches.

Changes in v2:
- Drop the -i2c suffixes from the compatible strings too (Geert Uytterhoeven)
- Don't add compatible strings with an "-spi" suffix (Geert Uytterhoeven)
- Use the compatible strings that don't have "fb-i2c" (Geert Uytterhoeven).
- Drop ssd13x_variant_to_info() and just use the array index (Neil Armstrong).
- Add the same compatible strings than I2C (Geert Uytterhoeven)
- Add Mark Brown's Acked-by tag to all patches.

Javier Martinez Canillas (5):
  dt-bindings: display: ssd1307fb: Deprecate "-i2c" compatible strings
  dt-bindings: display: ssd1307fb: Extend schema for SPI controllers
  drm/solomon: Add ssd130x new compatible strings and deprecate old
    ones.
  drm/solomon: Move device info from ssd130x-i2c to the core driver
  drm/solomon: Add SSD130x OLED displays SPI support

 .../bindings/display/solomon,ssd1307fb.yaml   |  82 ++++++--
 drivers/gpu/drm/solomon/Kconfig               |   9 +
 drivers/gpu/drm/solomon/Makefile              |   1 +
 drivers/gpu/drm/solomon/ssd130x-i2c.c         |  62 +++---
 drivers/gpu/drm/solomon/ssd130x-spi.c         | 177 ++++++++++++++++++
 drivers/gpu/drm/solomon/ssd130x.c             |  36 +++-
 drivers/gpu/drm/solomon/ssd130x.h             |  14 ++
 7 files changed, 324 insertions(+), 57 deletions(-)
 create mode 100644 drivers/gpu/drm/solomon/ssd130x-spi.c

-- 
2.35.1

[PATCH v3 1/5] dt-bindings: display: ssd1307fb: Deprecate "-i2c" compatible strings

[Javier Martinez Canillas]

The current compatible strings for SSD130x I2C controllers contain both an
"fb" and "-i2c" suffixes. It seems to indicate that are for a fbdev driver
and also that are for devices that can be accessed over an I2C bus.

But a DT is supposed to describe the hardware and not Linux implementation
details. So let's deprecate those compatible strings and add new ones that
only contain the vendor and device name, without any of these suffixes.

These will just describe the device and can be matched by both I2C and SPI
DRM drivers. The required properties should still be enforced for old ones.

While being there, just drop the "sinowealth,sh1106-i2c" compatible string
since that was never present in a released Linux version.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---

Changes in v3:
- Drop the "sinowealth,sh1106-i2c", wasn't in a released version (Chen-Yu Tsai)
- Continue enforcing required properties for deprecated strings (Maxime Ripard)

Changes in v2:
- Drop the -i2c suffixes from the compatible strings too (Geert Uytterhoeven)

 .../bindings/display/solomon,ssd1307fb.yaml   | 44 +++++++++++++------
 1 file changed, 31 insertions(+), 13 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml b/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
index ade61d502edd..7653b6c3fcb6 100644
--- a/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
+++ b/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
@@ -12,12 +12,22 @@ maintainers:
 
 properties:
   compatible:
-    enum:
-      - sinowealth,sh1106-i2c
-      - solomon,ssd1305fb-i2c
-      - solomon,ssd1306fb-i2c
-      - solomon,ssd1307fb-i2c
-      - solomon,ssd1309fb-i2c
+    oneOf:
+      # Deprecated compatible strings
+      - items:
+          - enum:
+              - solomon,ssd1305fb-i2c
+              - solomon,ssd1306fb-i2c
+              - solomon,ssd1307fb-i2c
+              - solomon,ssd1309fb-i2c
+        deprecated: true
+      - items:
+          - enum:
+              - sinowealth,sh1106
+              - solomon,ssd1305
+              - solomon,ssd1306
+              - solomon,ssd1307
+              - solomon,ssd1309
 
   reg:
     maxItems: 1
@@ -136,7 +146,7 @@ allOf:
       properties:
         compatible:
           contains:
-            const: sinowealth,sh1106-i2c
+            const: sinowealth,sh1106
     then:
       properties:
         solomon,dclk-div:
@@ -148,7 +158,9 @@ allOf:
       properties:
         compatible:
           contains:
-            const: solomon,ssd1305fb-i2c
+            enum:
+              - solomon,ssd1305-i2c
+              - solomon,ssd1305
     then:
       properties:
         solomon,dclk-div:
@@ -160,7 +172,9 @@ allOf:
       properties:
         compatible:
           contains:
-            const: solomon,ssd1306fb-i2c
+            enum:
+              - solomon,ssd1306-i2c
+              - solomon,ssd1306
     then:
       properties:
         solomon,dclk-div:
@@ -172,7 +186,9 @@ allOf:
       properties:
         compatible:
           contains:
-            const: solomon,ssd1307fb-i2c
+            enum:
+              - solomon,ssd1307-i2c
+              - solomon,ssd1307
     then:
       properties:
         solomon,dclk-div:
@@ -186,7 +202,9 @@ allOf:
       properties:
         compatible:
           contains:
-            const: solomon,ssd1309fb-i2c
+            enum:
+              - solomon,ssd1309-i2c
+              - solomon,ssd1309
     then:
       properties:
         solomon,dclk-div:
@@ -203,14 +221,14 @@ examples:
             #size-cells = <0>;
 
             ssd1307: oled@3c {
-                    compatible = "solomon,ssd1307fb-i2c";
+                    compatible = "solomon,ssd1307";
                     reg = <0x3c>;
                     pwms = <&pwm 4 3000>;
                     reset-gpios = <&gpio2 7>;
             };
 
             ssd1306: oled@3d {
-                    compatible = "solomon,ssd1306fb-i2c";
+                    compatible = "solomon,ssd1306";
                     reg = <0x3c>;
                     pwms = <&pwm 4 3000>;
                     reset-gpios = <&gpio2 7>;
-- 
2.35.1

[PATCH v3 2/5] dt-bindings: display: ssd1307fb: Extend schema for SPI controllers

[Javier Martinez Canillas]

The Solomon SSD130x OLED displays can either have an I2C or SPI interface,
add to the schema the properties and examples for OLED devices under SPI.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---

Changes in v3:
- Add a comment to the properties required for SPI (Geert Uytterhoeven)

Changes in v2:
- Don't add compatible strings with an "-spi" suffix (Geert Uytterhoeven)

 .../bindings/display/solomon,ssd1307fb.yaml   | 38 ++++++++++++++++++-
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml b/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
index 7653b6c3fcb6..7d7de92df86f 100644
--- a/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
+++ b/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
@@ -38,9 +38,16 @@ properties:
   reset-gpios:
     maxItems: 1
 
+  # Only required for SPI
+  dc-gpios:
+    maxItems: 1
+
   vbat-supply:
     description: The supply for VBAT
 
+  # Only required for SPI
+  spi-max-frequency: true
+
   solomon,height:
     $ref: /schemas/types.yaml#/definitions/uint32
     default: 16
@@ -220,14 +227,14 @@ examples:
             #address-cells = <1>;
             #size-cells = <0>;
 
-            ssd1307: oled@3c {
+            ssd1307_i2c: oled@3c {
                     compatible = "solomon,ssd1307";
                     reg = <0x3c>;
                     pwms = <&pwm 4 3000>;
                     reset-gpios = <&gpio2 7>;
             };
 
-            ssd1306: oled@3d {
+            ssd1306_i2c: oled@3d {
                     compatible = "solomon,ssd1306";
                     reg = <0x3c>;
                     pwms = <&pwm 4 3000>;
@@ -238,3 +245,30 @@ examples:
                     solomon,lookup-table = /bits/ 8 <0x3f 0x3f 0x3f 0x3f>;
             };
     };
+  - |
+    spi {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            ssd1307_spi: oled@0 {
+                    compatible = "solomon,ssd1307";
+                    reg = <0x0>;
+                    pwms = <&pwm 4 3000>;
+                    reset-gpios = <&gpio2 7>;
+                    dc-gpios = <&gpio2 8>;
+                    spi-max-frequency = <10000000>;
+            };
+
+            ssd1306_spi: oled@1 {
+                    compatible = "solomon,ssd1306";
+                    reg = <0x1>;
+                    pwms = <&pwm 4 3000>;
+                    reset-gpios = <&gpio2 7>;
+                    dc-gpios = <&gpio2 8>;
+                    spi-max-frequency = <10000000>;
+                    solomon,com-lrremap;
+                    solomon,com-invdir;
+                    solomon,com-offset = <32>;
+                    solomon,lookup-table = /bits/ 8 <0x3f 0x3f 0x3f 0x3f>;
+            };
+    };
-- 
2.35.1

[PATCH v3 3/5] drm/solomon: Add ssd130x new compatible strings and deprecate old ones.

[Javier Martinez Canillas]

The current compatible strings for SSD130x I2C controllers contain an "fb"
and "-i2c" suffixes. These have been deprecated and more correct ones were
added, that don't encode a subsystem or bus used to interface the devices.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---

Changes in v3:
- Drop the "sinowealth,sh1106-i2c", wasn't in a released version (Chen-Yu Tsai)

Changes in v2:
- Use the compatible strings that don't have "fb-i2c" (Geert Uytterhoeven).

 drivers/gpu/drm/solomon/ssd130x-i2c.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x-i2c.c b/drivers/gpu/drm/solomon/ssd130x-i2c.c
index d099b241dd3f..45867ef2bc8b 100644
--- a/drivers/gpu/drm/solomon/ssd130x-i2c.c
+++ b/drivers/gpu/drm/solomon/ssd130x-i2c.c
@@ -88,9 +88,26 @@ static struct ssd130x_deviceinfo ssd130x_ssd1309_deviceinfo = {
 
 static const struct of_device_id ssd130x_of_match[] = {
 	{
-		.compatible = "sinowealth,sh1106-i2c",
+		.compatible = "sinowealth,sh1106",
 		.data = &ssd130x_sh1106_deviceinfo,
 	},
+	{
+		.compatible = "solomon,ssd1305",
+		.data = &ssd130x_ssd1305_deviceinfo,
+	},
+	{
+		.compatible = "solomon,ssd1306",
+		.data = &ssd130x_ssd1306_deviceinfo,
+	},
+	{
+		.compatible = "solomon,ssd1307",
+		.data = &ssd130x_ssd1307_deviceinfo,
+	},
+	{
+		.compatible = "solomon,ssd1309",
+		.data = &ssd130x_ssd1309_deviceinfo,
+	},
+	/* Deprecated but kept for backward compatibility */
 	{
 		.compatible = "solomon,ssd1305fb-i2c",
 		.data = &ssd130x_ssd1305_deviceinfo,
-- 
2.35.1

[PATCH v3 4/5] drm/solomon: Move device info from ssd130x-i2c to the core driver

[Javier Martinez Canillas]

These are declared in the ssd130x-i2c transport driver but the information
is not I2C specific, and could be used by other SSD130x transport drivers.

Move them to the ssd130x core driver and just set the OF device entries to
an ID that could be used to lookup the correct device info from an array.

While being there, also move the SSD130X_DATA and SSD130X_COMMAND control
bytes. Since even though they are used by the I2C interface, they could
also be useful for other transport protocols such as SPI.

Suggested-by: Chen-Yu Tsai <wens@kernel.org>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---

Changes in v3:
- s/it/they in the commit description (Geert Uytterhoeven)
- Drop unnecessary blank line (Geert Uytterhoeven)
- Export variants array and use &info[ID] in device table (Andy Shevchenko)

Changes in v2:
- Drop ssd13x_variant_to_info() and just use the array index (Neil Armstrong).

 drivers/gpu/drm/solomon/ssd130x-i2c.c | 51 +++++----------------------
 drivers/gpu/drm/solomon/ssd130x.c     | 36 +++++++++++++++++--
 drivers/gpu/drm/solomon/ssd130x.h     | 14 ++++++++
 3 files changed, 56 insertions(+), 45 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x-i2c.c b/drivers/gpu/drm/solomon/ssd130x-i2c.c
index 45867ef2bc8b..13b0713e31ad 100644
--- a/drivers/gpu/drm/solomon/ssd130x-i2c.c
+++ b/drivers/gpu/drm/solomon/ssd130x-i2c.c
@@ -53,76 +53,43 @@ static void ssd130x_i2c_shutdown(struct i2c_client *client)
 	ssd130x_shutdown(ssd130x);
 }
 
-static struct ssd130x_deviceinfo ssd130x_sh1106_deviceinfo = {
-	.default_vcomh = 0x40,
-	.default_dclk_div = 1,
-	.default_dclk_frq = 5,
-	.page_mode_only = 1,
-};
-
-static struct ssd130x_deviceinfo ssd130x_ssd1305_deviceinfo = {
-	.default_vcomh = 0x34,
-	.default_dclk_div = 1,
-	.default_dclk_frq = 7,
-};
-
-static struct ssd130x_deviceinfo ssd130x_ssd1306_deviceinfo = {
-	.default_vcomh = 0x20,
-	.default_dclk_div = 1,
-	.default_dclk_frq = 8,
-	.need_chargepump = 1,
-};
-
-static struct ssd130x_deviceinfo ssd130x_ssd1307_deviceinfo = {
-	.default_vcomh = 0x20,
-	.default_dclk_div = 2,
-	.default_dclk_frq = 12,
-	.need_pwm = 1,
-};
-
-static struct ssd130x_deviceinfo ssd130x_ssd1309_deviceinfo = {
-	.default_vcomh = 0x34,
-	.default_dclk_div = 1,
-	.default_dclk_frq = 10,
-};
-
 static const struct of_device_id ssd130x_of_match[] = {
 	{
 		.compatible = "sinowealth,sh1106",
-		.data = &ssd130x_sh1106_deviceinfo,
+		.data = &ssd130x_variants[SH1106_ID],
 	},
 	{
 		.compatible = "solomon,ssd1305",
-		.data = &ssd130x_ssd1305_deviceinfo,
+		.data = &ssd130x_variants[SSD1305_ID],
 	},
 	{
 		.compatible = "solomon,ssd1306",
-		.data = &ssd130x_ssd1306_deviceinfo,
+		.data = &ssd130x_variants[SSD1306_ID],
 	},
 	{
 		.compatible = "solomon,ssd1307",
-		.data = &ssd130x_ssd1307_deviceinfo,
+		.data = &ssd130x_variants[SSD1307_ID],
 	},
 	{
 		.compatible = "solomon,ssd1309",
-		.data = &ssd130x_ssd1309_deviceinfo,
+		.data = &ssd130x_variants[SSD1309_ID],
 	},
 	/* Deprecated but kept for backward compatibility */
 	{
 		.compatible = "solomon,ssd1305fb-i2c",
-		.data = &ssd130x_ssd1305_deviceinfo,
+		.data = &ssd130x_variants[SSD1305_ID],
 	},
 	{
 		.compatible = "solomon,ssd1306fb-i2c",
-		.data = &ssd130x_ssd1306_deviceinfo,
+		.data = &ssd130x_variants[SSD1306_ID],
 	},
 	{
 		.compatible = "solomon,ssd1307fb-i2c",
-		.data = &ssd130x_ssd1307_deviceinfo,
+		.data = &ssd130x_variants[SSD1307_ID],
 	},
 	{
 		.compatible = "solomon,ssd1309fb-i2c",
-		.data = &ssd130x_ssd1309_deviceinfo,
+		.data = &ssd130x_variants[SSD1309_ID],
 	},
 	{ /* sentinel */ }
 };
diff --git a/drivers/gpu/drm/solomon/ssd130x.c b/drivers/gpu/drm/solomon/ssd130x.c
index a7e784518c69..c9b80ab8727b 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -39,11 +39,9 @@
 #define DRIVER_MAJOR	1
 #define DRIVER_MINOR	0
 
-#define SSD130X_DATA				0x40
-#define SSD130X_COMMAND				0x80
-
 #define SSD130X_PAGE_COL_START_LOW		0x00
 #define SSD130X_PAGE_COL_START_HIGH		0x10
+
 #define SSD130X_SET_ADDRESS_MODE		0x20
 #define SSD130X_SET_COL_RANGE			0x21
 #define SSD130X_SET_PAGE_RANGE			0x22
@@ -94,6 +92,38 @@
 
 #define MAX_CONTRAST 255
 
+const struct ssd130x_deviceinfo ssd130x_variants[] = {
+	[SH1106_ID] = {
+		.default_vcomh = 0x40,
+		.default_dclk_div = 1,
+		.default_dclk_frq = 5,
+		.page_mode_only = 1,
+	},
+	[SSD1305_ID] = {
+		.default_vcomh = 0x34,
+		.default_dclk_div = 1,
+		.default_dclk_frq = 7,
+	},
+	[SSD1306_ID] = {
+		.default_vcomh = 0x20,
+		.default_dclk_div = 1,
+		.default_dclk_frq = 8,
+		.need_chargepump = 1,
+	},
+	[SSD1307_ID] = {
+		.default_vcomh = 0x20,
+		.default_dclk_div = 2,
+		.default_dclk_frq = 12,
+		.need_pwm = 1,
+	},
+	[SSD1309_ID] = {
+		.default_vcomh = 0x34,
+		.default_dclk_div = 1,
+		.default_dclk_frq = 10,
+	}
+};
+EXPORT_SYMBOL_GPL(ssd130x_variants);
+
 static inline struct ssd130x_device *drm_to_ssd130x(struct drm_device *drm)
 {
 	return container_of(drm, struct ssd130x_device, drm);
diff --git a/drivers/gpu/drm/solomon/ssd130x.h b/drivers/gpu/drm/solomon/ssd130x.h
index f5b062576fdf..d14f78c2eb07 100644
--- a/drivers/gpu/drm/solomon/ssd130x.h
+++ b/drivers/gpu/drm/solomon/ssd130x.h
@@ -18,6 +18,18 @@
 
 #include <linux/regmap.h>
 
+#define SSD130X_DATA				0x40
+#define SSD130X_COMMAND				0x80
+
+enum ssd130x_variants {
+	SH1106_ID,
+	SSD1305_ID,
+	SSD1306_ID,
+	SSD1307_ID,
+	SSD1309_ID,
+	NR_SSD130X_VARIANTS
+};
+
 struct ssd130x_deviceinfo {
 	u32 default_vcomh;
 	u32 default_dclk_div;
@@ -71,6 +83,8 @@ struct ssd130x_device {
 	u8 page_end;
 };
 
+extern const struct ssd130x_deviceinfo ssd130x_variants[];
+
 struct ssd130x_device *ssd130x_probe(struct device *dev, struct regmap *regmap);
 int ssd130x_remove(struct ssd130x_device *ssd130x);
 void ssd130x_shutdown(struct ssd130x_device *ssd130x);
-- 
2.35.1

[PATCH v3 5/5] drm/solomon: Add SSD130x OLED displays SPI support

[Javier Martinez Canillas]

The ssd130x driver only provides the core support for these devices but it
does not have any bus transport logic. Add a driver to interface over SPI.

There is a difference in the communication protocol when using 4-wire SPI
instead of I2C. For the latter, a control byte that contains a D/C# field
has to be sent. This field tells the controller whether the data has to be
written to the command register or to the graphics display data memory.

But for 4-wire SPI that control byte is not used, instead a real D/C# line
must be pulled HIGH for commands data and LOW for graphics display data.

For this reason the standard SPI regmap can't be used and a custom .write
bus handler is needed.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
---

Changes in v3:
- Drop ssd130x_spi_get_dc() helper and open code it (Geert Uytterhoeven)
- Export variants array and use &info[ID] in device table (Andy Shevchenko)

Changes in v2:
- Add the same compatible strings than I2C (Geert Uytterhoeven)

 drivers/gpu/drm/solomon/Kconfig       |   9 ++
 drivers/gpu/drm/solomon/Makefile      |   1 +
 drivers/gpu/drm/solomon/ssd130x-spi.c | 177 ++++++++++++++++++++++++++
 3 files changed, 187 insertions(+)
 create mode 100644 drivers/gpu/drm/solomon/ssd130x-spi.c

diff --git a/drivers/gpu/drm/solomon/Kconfig b/drivers/gpu/drm/solomon/Kconfig
index 8c0a0c788385..e170716d976b 100644
--- a/drivers/gpu/drm/solomon/Kconfig
+++ b/drivers/gpu/drm/solomon/Kconfig
@@ -20,3 +20,12 @@ config DRM_SSD130X_I2C
 	  I2C bus.
 
 	  If M is selected the module will be called ssd130x-i2c.
+
+config DRM_SSD130X_SPI
+	tristate "DRM support for Solomon SSD130X OLED displays (SPI bus)"
+	depends on DRM_SSD130X && SPI
+	select REGMAP
+	help
+	  Say Y here if the SSD130x OLED display is connected via SPI bus.
+
+	  If M is selected the module will be called ssd130x-spi.
diff --git a/drivers/gpu/drm/solomon/Makefile b/drivers/gpu/drm/solomon/Makefile
index 4bfc5acb0447..b5fc792257d7 100644
--- a/drivers/gpu/drm/solomon/Makefile
+++ b/drivers/gpu/drm/solomon/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_DRM_SSD130X)	+= ssd130x.o
 obj-$(CONFIG_DRM_SSD130X_I2C)	+= ssd130x-i2c.o
+obj-$(CONFIG_DRM_SSD130X_SPI)	+= ssd130x-spi.o
diff --git a/drivers/gpu/drm/solomon/ssd130x-spi.c b/drivers/gpu/drm/solomon/ssd130x-spi.c
new file mode 100644
index 000000000000..4fda420ae0a6
--- /dev/null
+++ b/drivers/gpu/drm/solomon/ssd130x-spi.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * DRM driver for Solomon SSD130X OLED displays (SPI bus)
+ *
+ * Copyright 2022 Red Hat Inc.
+ * Authors: Javier Martinez Canillas <javierm@redhat.com>
+ */
+#include <linux/spi/spi.h>
+#include <linux/module.h>
+
+#include "ssd130x.h"
+
+#define DRIVER_NAME	"ssd130x-spi"
+#define DRIVER_DESC	"DRM driver for Solomon SSD130X OLED displays (SPI)"
+
+struct ssd130x_spi_transport {
+	struct spi_device *spi;
+	struct gpio_desc *dc;
+};
+
+static const struct regmap_config ssd130x_spi_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+/*
+ * The regmap bus .write handler, it is just a wrapper around spi_write()
+ * but toggling the Data/Command control pin (D/C#). Since for 4-wire SPI
+ * a D/C# pin is used, in contrast with I2C where a control byte is sent,
+ * prior to every data byte, that contains a bit with the D/C# value.
+ *
+ * These control bytes are considered registers by the ssd130x core driver
+ * and can be used by the ssd130x SPI driver to determine if the data sent
+ * is for a command register or for the Graphic Display Data RAM (GDDRAM).
+ */
+static int ssd130x_spi_write(void *context, const void *data, size_t count)
+{
+	struct ssd130x_spi_transport *t = context;
+	struct spi_device *spi = t->spi;
+	const u8 *reg = data;
+
+	if (*reg == SSD130X_COMMAND)
+		gpiod_set_value_cansleep(t->dc, 0);
+
+	if (*reg == SSD130X_DATA)
+		gpiod_set_value_cansleep(t->dc, 1);
+
+	/* Remove the control byte since is not used by the 4-wire SPI */
+	return spi_write(spi, ((u8 *)data) + 1, count - 1);
+}
+
+/* The ssd130x driver does not read registers but regmap expects a .read */
+static int ssd130x_spi_read(void *context, const void *reg, size_t reg_size,
+			    void *val, size_t val_size)
+{
+	return -EOPNOTSUPP;
+}
+
+/*
+ * A custom bus is needed due the special write that toggles a D/C# pin,
+ * another option could be to just have a .reg_write() callback but that
+ * will prevent to do data writes in bulk.
+ *
+ * Once the regmap API is extended to support defining a bulk write handler
+ * in the struct regmap_config, this can be simplified and the bus dropped.
+ */
+static struct regmap_bus regmap_ssd130x_spi_bus = {
+	.write = ssd130x_spi_write,
+	.read = ssd130x_spi_read,
+};
+
+static int ssd130x_spi_probe(struct spi_device *spi)
+{
+	struct ssd130x_spi_transport *t;
+	struct ssd130x_device *ssd130x;
+	struct regmap *regmap;
+	struct gpio_desc *dc;
+	struct device *dev = &spi->dev;
+
+	dc = devm_gpiod_get(dev, "dc", GPIOD_OUT_LOW);
+	if (IS_ERR(dc))
+		return dev_err_probe(dev, PTR_ERR(dc),
+				     "Failed to get dc gpio\n");
+
+	t = devm_kzalloc(dev, sizeof(*t), GFP_KERNEL);
+	if (!t)
+		return dev_err_probe(dev, -ENOMEM,
+				     "Failed to allocate SPI transport data\n");
+
+	t->spi = spi;
+	t->dc = dc;
+
+	regmap = devm_regmap_init(dev, &regmap_ssd130x_spi_bus, t,
+				  &ssd130x_spi_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ssd130x = ssd130x_probe(dev, regmap);
+	if (IS_ERR(ssd130x))
+		return PTR_ERR(ssd130x);
+
+	spi_set_drvdata(spi, ssd130x);
+
+	return 0;
+}
+
+static void ssd130x_spi_remove(struct spi_device *spi)
+{
+	struct ssd130x_device *ssd130x = spi_get_drvdata(spi);
+
+	ssd130x_remove(ssd130x);
+}
+
+static void ssd130x_spi_shutdown(struct spi_device *spi)
+{
+	struct ssd130x_device *ssd130x = spi_get_drvdata(spi);
+
+	ssd130x_shutdown(ssd130x);
+}
+
+static const struct of_device_id ssd130x_of_match[] = {
+	{
+		.compatible = "sinowealth,sh1106",
+		.data = &ssd130x_variants[SH1106_ID],
+	},
+	{
+		.compatible = "solomon,ssd1305",
+		.data = &ssd130x_variants[SSD1305_ID],
+	},
+	{
+		.compatible = "solomon,ssd1306",
+		.data = &ssd130x_variants[SSD1306_ID],
+	},
+	{
+		.compatible = "solomon,ssd1307",
+		.data = &ssd130x_variants[SSD1307_ID],
+	},
+	{
+		.compatible = "solomon,ssd1309",
+		.data = &ssd130x_variants[SSD1309_ID],
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ssd130x_of_match);
+
+/*
+ * The SPI core always reports a MODALIAS uevent of the form "spi:<dev>", even
+ * if the device was registered via OF. This means that the module will not be
+ * auto loaded, unless it contains an alias that matches the MODALIAS reported.
+ *
+ * To workaround this issue, add a SPI device ID table. Even when this should
+ * not be needed for this driver to match the registered SPI devices.
+ */
+static const struct spi_device_id ssd130x_spi_table[] = {
+	{ "sh1106",  SH1106_ID },
+	{ "ssd1305", SSD1305_ID },
+	{ "ssd1306", SSD1306_ID },
+	{ "ssd1307", SSD1307_ID },
+	{ "ssd1309", SSD1309_ID },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(spi, ssd130x_spi_table);
+
+static struct spi_driver ssd130x_spi_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = ssd130x_of_match,
+	},
+	.probe = ssd130x_spi_probe,
+	.remove = ssd130x_spi_remove,
+	.shutdown = ssd130x_spi_shutdown,
+};
+module_spi_driver(ssd130x_spi_driver);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Javier Martinez Canillas <javierm@redhat.com>");
+MODULE_LICENSE("GPL");
-- 
2.35.1

Re: [PATCH v3 2/5] dt-bindings: display: ssd1307fb: Extend schema for SPI controllers

[Geert Uytterhoeven]

Hi Javier,

On Tue, Apr 12, 2022 at 6:27 PM Javier Martinez Canillas
<javierm@redhat.com> wrote:
> The Solomon SSD130x OLED displays can either have an I2C or SPI interface,
> add to the schema the properties and examples for OLED devices under SPI.
>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> Acked-by: Mark Brown <broonie@kernel.org>
> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
>
> Changes in v3:
> - Add a comment to the properties required for SPI (Geert Uytterhoeven)

Thanks for the update!

> --- a/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
> +++ b/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
> @@ -38,9 +38,16 @@ properties:
>    reset-gpios:
>      maxItems: 1
>
> +  # Only required for SPI
> +  dc-gpios:
> +    maxItems: 1

Actually I meant to also add a description, like for vbat-supply below,
to explain the meaning of "dc".

> +
>    vbat-supply:
>      description: The supply for VBAT

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v3 2/5] dt-bindings: display: ssd1307fb: Extend schema for SPI controllers

[Javier Martinez Canillas]

Hello Geert,

On 4/13/22 10:04, Geert Uytterhoeven wrote:
> Hi Javier,
> 
> On Tue, Apr 12, 2022 at 6:27 PM Javier Martinez Canillas
> <javierm@redhat.com> wrote:
>> The Solomon SSD130x OLED displays can either have an I2C or SPI interface,
>> add to the schema the properties and examples for OLED devices under SPI.
>>
>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
>> Acked-by: Mark Brown <broonie@kernel.org>
>> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> ---
>>
>> Changes in v3:
>> - Add a comment to the properties required for SPI (Geert Uytterhoeven)
> 
> Thanks for the update!
> 
>> --- a/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
>> +++ b/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
>> @@ -38,9 +38,16 @@ properties:
>>    reset-gpios:
>>      maxItems: 1
>>
>> +  # Only required for SPI
>> +  dc-gpios:
>> +    maxItems: 1
> 
> Actually I meant to also add a description, like for vbat-supply below,
> to explain the meaning of "dc".
>

Ahh, sorry for misunderstanding you! Something like the following looks good ?

  # Only required for SPI
  dc-gpios:
    description:
      GPIO connected to the controller's D/C# (Data/Command) pin,
      that is needed for 4-wire SPI to tell the controller if the
      data sent is for a command register or the display data RAM
    maxItems: 1

If you agree with that, then can squash before pushing or add it to a v4
if another revision is needed.

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat

Re: [PATCH v3 2/5] dt-bindings: display: ssd1307fb: Extend schema for SPI controllers

[Geert Uytterhoeven]

Hi Javier,

On Wed, Apr 13, 2022 at 11:44 AM Javier Martinez Canillas
<javierm@redhat.com> wrote:
> On 4/13/22 10:04, Geert Uytterhoeven wrote:
> > On Tue, Apr 12, 2022 at 6:27 PM Javier Martinez Canillas
> > <javierm@redhat.com> wrote:
> >> The Solomon SSD130x OLED displays can either have an I2C or SPI interface,
> >> add to the schema the properties and examples for OLED devices under SPI.
> >>
> >> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> >> Acked-by: Mark Brown <broonie@kernel.org>
> >> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >> ---
> >>
> >> Changes in v3:
> >> - Add a comment to the properties required for SPI (Geert Uytterhoeven)
> >
> > Thanks for the update!
> >
> >> --- a/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
> >> +++ b/Documentation/devicetree/bindings/display/solomon,ssd1307fb.yaml
> >> @@ -38,9 +38,16 @@ properties:
> >>    reset-gpios:
> >>      maxItems: 1
> >>
> >> +  # Only required for SPI
> >> +  dc-gpios:
> >> +    maxItems: 1
> >
> > Actually I meant to also add a description, like for vbat-supply below,
> > to explain the meaning of "dc".
> >
>
> Ahh, sorry for misunderstanding you! Something like the following looks good ?
>
>   # Only required for SPI
>   dc-gpios:
>     description:
>       GPIO connected to the controller's D/C# (Data/Command) pin,
>       that is needed for 4-wire SPI to tell the controller if the
>       data sent is for a command register or the display data RAM
>     maxItems: 1
>
> If you agree with that, then can squash before pushing or add it to a v4
> if another revision is needed.

Thanks, LGTM.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v3 4/5] drm/solomon: Move device info from ssd130x-i2c to the core driver

[Andy Shevchenko]

On Tue, Apr 12, 2022 at 06:27:28PM +0200, Javier Martinez Canillas wrote:
> These are declared in the ssd130x-i2c transport driver but the information
> is not I2C specific, and could be used by other SSD130x transport drivers.
> 
> Move them to the ssd130x core driver and just set the OF device entries to
> an ID that could be used to lookup the correct device info from an array.
> 
> While being there, also move the SSD130X_DATA and SSD130X_COMMAND control
> bytes. Since even though they are used by the I2C interface, they could
> also be useful for other transport protocols such as SPI.

...

> +EXPORT_SYMBOL_GPL(ssd130x_variants);

What I meant is to use EXPORT_SYMBOL_NS_GPL() here. It might require a separate
patch to move other exports to that namespace first.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 4/5] drm/solomon: Move device info from ssd130x-i2c to the core driver

[Javier Martinez Canillas]

Hello Andy,

On 4/13/22 12:46, Andy Shevchenko wrote:
> On Tue, Apr 12, 2022 at 06:27:28PM +0200, Javier Martinez Canillas wrote:
>> These are declared in the ssd130x-i2c transport driver but the information
>> is not I2C specific, and could be used by other SSD130x transport drivers.
>>
>> Move them to the ssd130x core driver and just set the OF device entries to
>> an ID that could be used to lookup the correct device info from an array.
>>
>> While being there, also move the SSD130X_DATA and SSD130X_COMMAND control
>> bytes. Since even though they are used by the I2C interface, they could
>> also be useful for other transport protocols such as SPI.
> 
> ...
> 
>> +EXPORT_SYMBOL_GPL(ssd130x_variants);
> 
> What I meant is to use EXPORT_SYMBOL_NS_GPL() here. It might require a separate
> patch to move other exports to that namespace first.
> 

Oh, I wasn't aware of the namespace aware variant of these. Thanks for
pointing it out! I'll change and use that one instead for v4.

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat