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 ---

(no changes since v3)

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>;

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 ---

(no changes since v3)

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,

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 Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be ---

Changes in v5: - Remove cast by just using u8 *reg instead of void *data (Geert Uytterhoeven). - Add Geert Uytterhoeven's Reviewed-by tag to patch 5/5.

Changes in v4: - Use MODULE_IMPORT_NS(DRM_SSD130X) in the ssd130x-spi driver (Andy Shevchenko)

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 | 178 ++++++++++++++++++++++++++ 3 files changed, 188 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..43722adab1f8 --- /dev/null +++ b/drivers/gpu/drm/solomon/ssd130x-spi.c @@ -0,0 +1,178 @@ +// 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 control byte since is not used in a 4-wire SPI interface */ + return spi_write(spi, reg + 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"); +MODULE_IMPORT_NS(DRM_SSD130X);