drm/panel: Add driver for the AUO A030JTN01 TFT LCD

Add driver for the AUO A030JTN01 panel, which is a 320x480 3.0" 4:3
24-bit TFT LCD panel with non-square pixels and a delta-RGB 8-bit
interface.
Signed-off-by: Christophe Branchereau <cbranchereau@gmail.com>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230121162419.284523-3-cbranchereau@gmail.com

drivers/gpu/drm/panel/Kconfig

@@ -37,6 +37,14 @@ config DRM_PANEL_ASUS_Z00T_TM5P5_NT35596
 	  NT35596 1080x1920 video mode panel as found in some Asus
 	  Zenfone 2 Laser Z00T devices.
 
+config DRM_PANEL_AUO_A030JTN01
+	tristate "AUO A030JTN01"
+	depends on SPI
+	select REGMAP_SPI
+	help
+	  Say Y here to enable support for the AUO A030JTN01 320x480 3.0" panel
+	  as found in the YLM RS-97 handheld gaming console.
+
 config DRM_PANEL_BOE_BF060Y8M_AJ0
 	tristate "Boe BF060Y8M-AJ0 panel"
 	depends on OF

drivers/gpu/drm/panel/Makefile

@@ -2,6 +2,7 @@
 obj-$(CONFIG_DRM_PANEL_ABT_Y030XX067A) += panel-abt-y030xx067a.o
 obj-$(CONFIG_DRM_PANEL_ARM_VERSATILE) += panel-arm-versatile.o
 obj-$(CONFIG_DRM_PANEL_ASUS_Z00T_TM5P5_NT35596) += panel-asus-z00t-tm5p5-n35596.o
+obj-$(CONFIG_DRM_PANEL_AUO_A030JTN01) += panel-auo-a030jtn01.o
 obj-$(CONFIG_DRM_PANEL_BOE_BF060Y8M_AJ0) += panel-boe-bf060y8m-aj0.o
 obj-$(CONFIG_DRM_PANEL_BOE_HIMAX8279D) += panel-boe-himax8279d.o
 obj-$(CONFIG_DRM_PANEL_BOE_TV101WUM_NL6) += panel-boe-tv101wum-nl6.o

drivers/gpu/drm/panel/panel-auo-a030jtn01.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AU Optronics A030JTN01.0 TFT LCD panel driver
+ *
+ * Copyright (C) 2023, Paul Cercueil <paul@crapouillou.net>
+ * Copyright (C) 2023, Christophe Branchereau <cbranchereau@gmail.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/media-bus-format.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+
+#define REG05			0x05
+#define REG06			0x06
+#define REG07			0x07
+
+#define REG05_STDBY		BIT(0)
+#define REG06_VBLK		GENMASK(4, 0)
+#define REG07_HBLK		GENMASK(7, 0)
+
+
+struct a030jtn01_info {
+	const struct drm_display_mode *display_modes;
+	unsigned int num_modes;
+	u16 width_mm, height_mm;
+	u32 bus_format, bus_flags;
+};
+
+struct a030jtn01 {
+	struct drm_panel panel;
+	struct spi_device *spi;
+	struct regmap *map;
+
+	const struct a030jtn01_info *panel_info;
+
+	struct regulator *supply;
+	struct gpio_desc *reset_gpio;
+};
+
+static inline struct a030jtn01 *to_a030jtn01(struct drm_panel *panel)
+{
+	return container_of(panel, struct a030jtn01, panel);
+}
+
+static int a030jtn01_prepare(struct drm_panel *panel)
+{
+	struct a030jtn01 *priv = to_a030jtn01(panel);
+	struct device *dev = &priv->spi->dev;
+	unsigned int dummy;
+	int err;
+
+	err = regulator_enable(priv->supply);
+	if (err) {
+		dev_err(dev, "Failed to enable power supply: %d\n", err);
+		return err;
+	}
+
+	usleep_range(1000, 8000);
+
+	/* Reset the chip */
+	gpiod_set_value_cansleep(priv->reset_gpio, 1);
+	usleep_range(100, 8000);
+	gpiod_set_value_cansleep(priv->reset_gpio, 0);
+	usleep_range(2000, 8000);
+
+	/*
+	 * No idea why, but a register read (doesn't matter which) is needed to
+	 * properly initialize the chip after a reset; otherwise, the colors
+	 * will be wrong. It doesn't seem to be timing-related as a msleep(200)
+	 * doesn't fix it.
+	 */
+	err = regmap_read(priv->map, REG05, &dummy);
+	if (err)
+		goto err_disable_regulator;
+
+	/* Use (24 + 6) == 0x1e as the vertical back porch */
+	err = regmap_write(priv->map, REG06, FIELD_PREP(REG06_VBLK, 0x1e));
+	if (err)
+		goto err_disable_regulator;
+
+	/* Use (42 + 30) * 3 == 0xd8 as the horizontal back porch */
+	err = regmap_write(priv->map, REG07, FIELD_PREP(REG07_HBLK, 0xd8));
+	if (err)
+		goto err_disable_regulator;
+
+	return 0;
+
+err_disable_regulator:
+	gpiod_set_value_cansleep(priv->reset_gpio, 1);
+	regulator_disable(priv->supply);
+	return err;
+}
+
+static int a030jtn01_unprepare(struct drm_panel *panel)
+{
+	struct a030jtn01 *priv = to_a030jtn01(panel);
+
+	gpiod_set_value_cansleep(priv->reset_gpio, 1);
+	regulator_disable(priv->supply);
+
+	return 0;
+}
+
+static int a030jtn01_enable(struct drm_panel *panel)
+{
+	struct a030jtn01 *priv = to_a030jtn01(panel);
+	int ret;
+
+	ret = regmap_set_bits(priv->map, REG05, REG05_STDBY);
+	if (ret)
+		return ret;
+
+	/* Wait for the picture to be stable */
+	if (panel->backlight)
+		msleep(100);
+
+	return 0;
+}
+
+static int a030jtn01_disable(struct drm_panel *panel)
+{
+	struct a030jtn01 *priv = to_a030jtn01(panel);
+
+	return regmap_clear_bits(priv->map, REG05, REG05_STDBY);
+}
+
+static int a030jtn01_get_modes(struct drm_panel *panel,
+				struct drm_connector *connector)
+{
+	struct a030jtn01 *priv = to_a030jtn01(panel);
+	const struct a030jtn01_info *panel_info = priv->panel_info;
+	struct drm_display_mode *mode;
+	unsigned int i;
+
+	for (i = 0; i < panel_info->num_modes; i++) {
+		mode = drm_mode_duplicate(connector->dev,
+					  &panel_info->display_modes[i]);
+		if (!mode)
+			return -ENOMEM;
+
+		drm_mode_set_name(mode);
+
+		mode->type = DRM_MODE_TYPE_DRIVER;
+		if (panel_info->num_modes == 1)
+			mode->type |= DRM_MODE_TYPE_PREFERRED;
+
+		drm_mode_probed_add(connector, mode);
+	}
+
+	connector->display_info.bpc = 8;
+	connector->display_info.width_mm = panel_info->width_mm;
+	connector->display_info.height_mm = panel_info->height_mm;
+
+	drm_display_info_set_bus_formats(&connector->display_info,
+					 &panel_info->bus_format, 1);
+	connector->display_info.bus_flags = panel_info->bus_flags;
+
+	return panel_info->num_modes;
+}
+
+static const struct drm_panel_funcs a030jtn01_funcs = {
+	.prepare	= a030jtn01_prepare,
+	.unprepare	= a030jtn01_unprepare,
+	.enable		= a030jtn01_enable,
+	.disable	= a030jtn01_disable,
+	.get_modes	= a030jtn01_get_modes,
+};
+
+static bool a030jtn01_has_reg(struct device *dev, unsigned int reg)
+{
+	static const u32 a030jtn01_regs_mask = 0x001823f1fb;
+
+	return a030jtn01_regs_mask & BIT(reg);
+};
+
+static const struct regmap_config a030jtn01_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.read_flag_mask = 0x40,
+	.max_register = 0x1c,
+	.readable_reg = a030jtn01_has_reg,
+	.writeable_reg = a030jtn01_has_reg,
+};
+
+static int a030jtn01_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct a030jtn01 *priv;
+	int err;
+
+	spi->mode |= SPI_MODE_3 | SPI_3WIRE;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->spi = spi;
+	spi_set_drvdata(spi, priv);
+
+	priv->map = devm_regmap_init_spi(spi, &a030jtn01_regmap_config);
+	if (IS_ERR(priv->map))
+		return dev_err_probe(dev, PTR_ERR(priv->map), "Unable to init regmap");
+
+	priv->panel_info = spi_get_device_match_data(spi);
+	if (!priv->panel_info)
+		return -EINVAL;
+
+	priv->supply = devm_regulator_get(dev, "power");
+	if (IS_ERR(priv->supply))
+		return dev_err_probe(dev, PTR_ERR(priv->supply), "Failed to get power supply");
+
+	priv->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(priv->reset_gpio), "Failed to get reset GPIO");
+
+	drm_panel_init(&priv->panel, dev, &a030jtn01_funcs,
+		       DRM_MODE_CONNECTOR_DPI);
+
+	err = drm_panel_of_backlight(&priv->panel);
+	if (err)
+		return err;
+
+	drm_panel_add(&priv->panel);
+
+	return 0;
+}
+
+static void a030jtn01_remove(struct spi_device *spi)
+{
+	struct a030jtn01 *priv = spi_get_drvdata(spi);
+
+	drm_panel_remove(&priv->panel);
+	drm_panel_disable(&priv->panel);
+	drm_panel_unprepare(&priv->panel);
+}
+
+static const struct drm_display_mode a030jtn01_modes[] = {
+	{ /* 60 Hz */
+		.clock = 14400,
+		.hdisplay = 320,
+		.hsync_start = 320 + 8,
+		.hsync_end = 320 + 8 + 42,
+		.htotal = 320 + 8 + 42 + 30,
+		.vdisplay = 480,
+		.vsync_start = 480 + 90,
+		.vsync_end = 480 + 90 + 24,
+		.vtotal = 480 + 90 + 24 + 6,
+		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
+	},
+	{ /* 50 Hz */
+		.clock = 12000,
+		.hdisplay = 320,
+		.hsync_start = 320 + 8,
+		.hsync_end = 320 + 8 + 42,
+		.htotal = 320 + 8 + 42 + 30,
+		.vdisplay = 480,
+		.vsync_start = 480 + 90,
+		.vsync_end = 480 + 90 + 24,
+		.vtotal = 480 + 90 + 24 + 6,
+		.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
+	},
+};
+
+static const struct a030jtn01_info a030jtn01_info = {
+	.display_modes = a030jtn01_modes,
+	.num_modes = ARRAY_SIZE(a030jtn01_modes),
+	.width_mm = 70,
+	.height_mm = 51,
+	.bus_format = MEDIA_BUS_FMT_RGB888_3X8_DELTA,
+	.bus_flags = DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
+};
+
+static const struct spi_device_id a030jtn01_id[] = {
+	{ "a030jtn01", (kernel_ulong_t) &a030jtn01_info },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(spi, a030jtn01_id);
+
+static const struct of_device_id a030jtn01_of_match[] = {
+	{ .compatible = "auo,a030jtn01" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, a030jtn01_of_match);
+
+static struct spi_driver a030jtn01_driver = {
+	.driver = {
+		.name = "auo-a030jtn01",
+		.of_match_table = a030jtn01_of_match,
+	},
+	.id_table = a030jtn01_id,
+	.probe = a030jtn01_probe,
+	.remove = a030jtn01_remove,
+};
+module_spi_driver(a030jtn01_driver);
+
+MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
+MODULE_AUTHOR("Christophe Branchereau <cbranchereau@gmail.com>");
+MODULE_LICENSE("GPL");