From: Chris Morgan <macromor...@hotmail.com>

Support Samsung AMS495QA01 panel as found on the Anbernic RG503. Note
This panel receives video signals via DSI, however it receives
commands via 3-wire SPI.

Signed-off-by: Chris Morgan <macromor...@hotmail.com>
---
 drivers/gpu/drm/panel/Kconfig                 |  10 +
 drivers/gpu/drm/panel/Makefile                |   1 +
 .../gpu/drm/panel/panel-samsung-ams495qa01.c  | 468 ++++++++++++++++++
 3 files changed, 479 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-samsung-ams495qa01.c

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index a9043eacce97..954b66a2adee 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -444,6 +444,16 @@ config DRM_PANEL_RONBO_RB070D30
          Say Y here if you want to enable support for Ronbo Electronics
          RB070D30 1024x600 DSI panel.
 
+config DRM_PANEL_SAMSUNG_AMS495QA01
+       tristate "Samsung AMS495QA01 DSI panel"
+       depends on OF && SPI
+       depends on DRM_MIPI_DSI
+       select DRM_MIPI_DBI
+       help
+         DRM panel driver for the Samsung AMS495QA01 panel. This panel
+         receives video data via DSI but commands via 3-Wire 9-bit
+         SPI.
+
 config DRM_PANEL_SAMSUNG_ATNA33XC20
        tristate "Samsung ATNA33XC20 eDP panel"
        depends on OF
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index 34e717382dbb..de0b57baf851 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN) += 
panel-raspberrypi-touchscreen
 obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM67191) += panel-raydium-rm67191.o
 obj-$(CONFIG_DRM_PANEL_RAYDIUM_RM68200) += panel-raydium-rm68200.o
 obj-$(CONFIG_DRM_PANEL_RONBO_RB070D30) += panel-ronbo-rb070d30.o
+obj-$(CONFIG_DRM_PANEL_SAMSUNG_AMS495QA01) += panel-samsung-ams495qa01.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_ATNA33XC20) += panel-samsung-atna33xc20.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_DB7430) += panel-samsung-db7430.o
 obj-$(CONFIG_DRM_PANEL_SAMSUNG_LD9040) += panel-samsung-ld9040.o
diff --git a/drivers/gpu/drm/panel/panel-samsung-ams495qa01.c 
b/drivers/gpu/drm/panel/panel-samsung-ams495qa01.c
new file mode 100644
index 000000000000..60afea40a60e
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-samsung-ams495qa01.c
@@ -0,0 +1,468 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Samsung ams495qa01 MIPI-DSI panel driver
+ * Copyright (C) 2022 Chris Morgan
+ */
+
+#include <drm/drm_mipi_dbi.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/media-bus-format.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_graph.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <video/mipi_display.h>
+
+struct ams495qa01 {
+       /** @dev: the container device */
+       struct device *dev;
+       /** @dbi: the DBI bus abstraction handle */
+       struct mipi_dbi dbi;
+       /** @panel: the DRM panel instance for this device */
+       struct drm_panel panel;
+       /** @reset: reset GPIO line */
+       struct gpio_desc *reset;
+       /** @enable: enable GPIO line */
+       struct gpio_desc *enable;
+       /** @regulators: VDD and ELVDD supply regulators */
+       struct regulator_bulk_data regulators[2];
+       /** @dsi_dev: DSI child device (panel) */
+       struct mipi_dsi_device *dsi_dev;
+       /** @bl_dev: pseudo-backlight device for oled panel */
+       struct backlight_device *bl_dev;
+};
+
+static const struct drm_display_mode ams495qa01_mode = {
+       .clock = 33500,
+       .hdisplay = 960,
+       .hsync_start = 960 + 10,
+       .hsync_end = 960 + 10 + 2,
+       .htotal = 960 + 10 + 2 + 10,
+       .vdisplay = 544,
+       .vsync_start = 544 + 10,
+       .vsync_end = 544 + 10 + 2,
+       .vtotal = 544 + 10 + 2 + 10,
+       .width_mm = 117,
+       .height_mm = 74,
+       .flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
+};
+
+#define NUM_GAMMA_LEVELS       16
+#define GAMMA_TABLE_COUNT      23
+#define MAX_BRIGHTNESS         (NUM_GAMMA_LEVELS - 1)
+
+/* Table of gamma values provided in datasheet */
+static u8 ams495qa01_gamma[NUM_GAMMA_LEVELS][GAMMA_TABLE_COUNT] = {
+       {0x01, 0x79, 0x78, 0x8d, 0xd9, 0xdf, 0xd5, 0xcb, 0xcf, 0xc5,
+        0xe5, 0xe0, 0xe4, 0xdc, 0xb8, 0xd4, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x7d, 0x7c, 0x92, 0xd7, 0xdd, 0xd2, 0xcb, 0xd0, 0xc6,
+        0xe5, 0xe1, 0xe3, 0xda, 0xbd, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x7f, 0x7e, 0x95, 0xd7, 0xde, 0xd2, 0xcb, 0xcf, 0xc5,
+        0xe5, 0xe3, 0xe3, 0xda, 0xbf, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x82, 0x81, 0x99, 0xd6, 0xdd, 0xd1, 0xca, 0xcf, 0xc3,
+        0xe4, 0xe3, 0xe3, 0xda, 0xc2, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x84, 0x83, 0x9b, 0xd7, 0xde, 0xd2, 0xc8, 0xce, 0xc2,
+        0xe4, 0xe3, 0xe2, 0xd9, 0xc3, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x87, 0x86, 0x9f, 0xd6, 0xdd, 0xd1, 0xc7, 0xce, 0xc1,
+        0xe4, 0xe3, 0xe2, 0xd9, 0xc6, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x89, 0x89, 0xa2, 0xd5, 0xdb, 0xcf, 0xc8, 0xcf, 0xc2,
+        0xe3, 0xe3, 0xe1, 0xd9, 0xc7, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x8b, 0x8b, 0xa5, 0xd5, 0xdb, 0xcf, 0xc7, 0xce, 0xc0,
+        0xe3, 0xe3, 0xe1, 0xd8, 0xc7, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x8d, 0x8d, 0xa7, 0xd5, 0xdb, 0xcf, 0xc6, 0xce, 0xc0,
+        0xe4, 0xe4, 0xe1, 0xd7, 0xc8, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x8f, 0x8f, 0xaa, 0xd4, 0xdb, 0xce, 0xc6, 0xcd, 0xbf,
+        0xe3, 0xe3, 0xe1, 0xd7, 0xca, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x91, 0x91, 0xac, 0xd3, 0xda, 0xce, 0xc5, 0xcd, 0xbe,
+        0xe3, 0xe3, 0xe0, 0xd7, 0xca, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x93, 0x93, 0xaf, 0xd3, 0xda, 0xcd, 0xc5, 0xcd, 0xbe,
+        0xe2, 0xe3, 0xdf, 0xd6, 0xca, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x95, 0x95, 0xb1, 0xd2, 0xd9, 0xcc, 0xc4, 0xcd, 0xbe,
+        0xe2, 0xe3, 0xdf, 0xd7, 0xcc, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x99, 0x99, 0xb6, 0xd1, 0xd9, 0xcc, 0xc3, 0xcb, 0xbc,
+        0xe2, 0xe4, 0xdf, 0xd6, 0xcc, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x9c, 0x9c, 0xba, 0xd0, 0xd8, 0xcb, 0xc3, 0xcb, 0xbb,
+        0xe2, 0xe4, 0xdf, 0xd6, 0xce, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+       {0x01, 0x9f, 0x9f, 0xbe, 0xcf, 0xd7, 0xc9, 0xc2, 0xcb, 0xbb,
+        0xe1, 0xe3, 0xde, 0xd6, 0xd0, 0xd3, 0xfa, 0xed, 0xe6, 0x2f,
+        0x00, 0x2f},
+};
+
+/*
+ * Table of elvss values provided in datasheet and corresponds to
+ * gamma values.
+ */
+static u8 ams495qa01_elvss[NUM_GAMMA_LEVELS] = {
+       0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15, 0x15,
+       0x15, 0x15, 0x14, 0x14, 0x13, 0x12,
+};
+
+static inline struct ams495qa01 *to_ams495qa01(struct drm_panel *panel)
+{
+       return container_of(panel, struct ams495qa01, panel);
+}
+
+static int ams495qa01_update_gamma(struct mipi_dbi *dbi, u32 brightness)
+{
+       u32 tmp = brightness;
+
+       if (brightness > MAX_BRIGHTNESS)
+               tmp = MAX_BRIGHTNESS;
+
+       /* Set gamma values */
+       mipi_dbi_command_buf(dbi, 0xf9, ams495qa01_gamma[tmp],
+                            ARRAY_SIZE(ams495qa01_gamma[tmp]));
+       /* Set gamma change */
+       mipi_dbi_command(dbi, 0xf9, 0x00);
+       /* Undocumented command */
+       mipi_dbi_command(dbi, 0x26, 0x00);
+       /* Set ELVSS value */
+       mipi_dbi_command(dbi, 0xb2, ams495qa01_elvss[tmp]);
+
+       return 0;
+}
+
+static int ams495qa01_prepare(struct drm_panel *panel)
+{
+       struct ams495qa01 *db = to_ams495qa01(panel);
+       struct mipi_dbi *dbi = &db->dbi;
+       int ret;
+
+       /* Power up */
+       ret = regulator_bulk_enable(ARRAY_SIZE(db->regulators),
+                                   db->regulators);
+       if (ret) {
+               dev_err(db->dev, "failed to enable regulators: %d\n", ret);
+               return ret;
+       }
+
+       /* Enable */
+       if (db->enable)
+               gpiod_set_value_cansleep(db->enable, 1);
+
+       msleep(50);
+
+       /* Reset */
+       gpiod_set_value_cansleep(db->reset, 1);
+       usleep_range(1000, 5000);
+       gpiod_set_value_cansleep(db->reset, 0);
+       msleep(20);
+
+       /* Panel Init Sequence */
+
+       /* Password to start command sequence */
+       mipi_dbi_command(dbi, 0xf0, 0x5a, 0x5a);
+       mipi_dbi_command(dbi, 0xf1, 0x5a, 0x5a);
+
+       /* Undocumented commands */
+       mipi_dbi_command(dbi, 0xb0, 0x02);
+       mipi_dbi_command(dbi, 0xf3, 0x3b);
+
+       /* Analog Power condition set */
+       mipi_dbi_command(dbi, 0xf4, 0x33, 0x42, 0x00, 0x08);
+       mipi_dbi_command(dbi, 0xf5, 0x00, 0x06, 0x26, 0x35, 0x03);
+
+       /* Undocumented commands */
+       mipi_dbi_command(dbi, 0xf6, 0x02);
+       mipi_dbi_command(dbi, 0xc6, 0x0b, 0x00, 0x00, 0x3c, 0x00, 0x22,
+                        0x00, 0x00, 0x00, 0x00);
+
+       /* GTCON set */
+       mipi_dbi_command(dbi, 0xf7, 0x20);
+
+       /* TEMP_SWIRE set */
+       mipi_dbi_command(dbi, 0xb2, 0x06, 0x06, 0x06, 0x06);
+
+       /* ELVSS_CON set */
+       mipi_dbi_command(dbi, 0xb1, 0x07, 0x00, 0x10);
+
+       /* Gateless signal set */
+       mipi_dbi_command(dbi, 0xf8, 0x7f, 0x7a, 0x89, 0x67, 0x26, 0x38,
+                        0x00, 0x00, 0x09, 0x67, 0x70, 0x88, 0x7a,
+                        0x76, 0x05, 0x09, 0x23, 0x23, 0x23);
+
+       /* Undocumented commands */
+       mipi_dbi_command(dbi, 0xb5, 0xff, 0xef, 0x35, 0x42, 0x0d, 0xd7,
+                        0xff, 0x07, 0xff, 0xff, 0xfd, 0x00, 0x01,
+                        0xff, 0x05, 0x12, 0x0f, 0xff, 0xff, 0xff,
+                        0xff);
+       mipi_dbi_command(dbi, 0xb4, 0x15);
+       mipi_dbi_command(dbi, 0xb3, 0x00);
+
+       ams495qa01_update_gamma(dbi, MAX_BRIGHTNESS);
+
+       mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
+       msleep(200);
+       mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
+       usleep_range(10000, 15000);
+
+       return 0;
+}
+
+static int ams495qa01_unprepare(struct drm_panel *panel)
+{
+       struct ams495qa01 *db = to_ams495qa01(panel);
+       struct mipi_dbi *dbi = &db->dbi;
+
+       /* Panel Exit Sequence */
+       mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
+       msleep(20);
+       mipi_dbi_command(dbi, MIPI_DCS_ENTER_SLEEP_MODE);
+       usleep_range(10000, 15000);
+
+       gpiod_set_value_cansleep(db->reset, 0);
+
+       if (db->enable)
+               gpiod_set_value_cansleep(db->enable, 0);
+       regulator_bulk_disable(ARRAY_SIZE(db->regulators),
+                              db->regulators);
+       msleep(20);
+
+       return 0;
+}
+
+static int ams495qa01_get_modes(struct drm_panel *panel,
+                               struct drm_connector *connector)
+{
+       struct ams495qa01 *db = to_ams495qa01(panel);
+       struct drm_display_mode *mode;
+       static const u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24;
+
+       mode = drm_mode_duplicate(connector->dev, &ams495qa01_mode);
+       if (!mode) {
+               dev_err(db->dev, "failed to add mode\n");
+               return -ENOMEM;
+       }
+
+       connector->display_info.bpc = 8;
+       connector->display_info.width_mm = mode->width_mm;
+       connector->display_info.height_mm = mode->height_mm;
+       connector->display_info.bus_flags =
+               DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE |
+               DRM_BUS_FLAG_DE_LOW;
+       drm_display_info_set_bus_formats(&connector->display_info,
+                                        &bus_format, 1);
+
+       drm_mode_set_name(mode);
+       mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+
+       drm_mode_probed_add(connector, mode);
+
+       return 1;
+}
+
+static const struct drm_panel_funcs ams495qa01_drm_funcs = {
+       .unprepare = ams495qa01_unprepare,
+       .prepare = ams495qa01_prepare,
+       .get_modes = ams495qa01_get_modes,
+};
+
+static int ams495qa01_set_brightness(struct backlight_device *bd)
+{
+       struct ams495qa01 *db = bl_get_data(bd);
+       struct mipi_dbi *dbi = &db->dbi;
+       int brightness = bd->props.brightness;
+
+       ams495qa01_update_gamma(dbi, brightness);
+
+       return 0;
+}
+
+static const struct backlight_ops ams495qa01_backlight_ops = {
+       .update_status  = ams495qa01_set_brightness,
+};
+
+static int ams495qa01_backlight_register(struct ams495qa01 *db)
+{
+       struct backlight_properties props = {
+               .type           = BACKLIGHT_RAW,
+               .brightness     = MAX_BRIGHTNESS,
+               .max_brightness = MAX_BRIGHTNESS,
+       };
+       struct device *dev = db->dev;
+       int ret = 0;
+
+       db->bl_dev = devm_backlight_device_register(dev, "panel", dev, db,
+                                                    &ams495qa01_backlight_ops,
+                                                    &props);
+       if (IS_ERR(db->bl_dev)) {
+               ret = PTR_ERR(db->bl_dev);
+               dev_err(dev, "error registering backlight device (%d)\n", ret);
+       }
+
+       return ret;
+}
+
+static int ams495qa01_probe(struct spi_device *spi)
+{
+       struct device *dev = &spi->dev;
+       struct device_node *endpoint, *dsi_host_node;
+       struct mipi_dsi_host *dsi_host;
+       struct ams495qa01 *db;
+       int ret;
+       struct mipi_dsi_device_info info = {
+               .type = "dupa",
+               .channel = 0,
+               .node = NULL,
+       };
+
+       db = devm_kzalloc(dev, sizeof(*db), GFP_KERNEL);
+       if (!db)
+               return -ENOMEM;
+
+       spi_set_drvdata(spi, db);
+
+       db->dev = dev;
+
+       /*
+        * VCI   is the analog voltage supply
+        * VCCIO is the digital I/O voltage supply
+        */
+       db->regulators[0].supply = "vdd";
+       db->regulators[1].supply = "elvdd";
+       ret = devm_regulator_bulk_get(dev,
+                                     ARRAY_SIZE(db->regulators),
+                                     db->regulators);
+       if (ret)
+               return dev_err_probe(dev, ret, "failed to get regulators\n");
+
+       db->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
+       if (IS_ERR(db->reset)) {
+               ret = PTR_ERR(db->reset);
+               return dev_err_probe(dev, ret, "no RESET GPIO\n");
+       }
+
+       db->enable = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH);
+       if (IS_ERR(db->enable)) {
+               ret = PTR_ERR(db->enable);
+               return dev_err_probe(dev, ret, "cannot get ENABLE GPIO\n");
+       }
+
+       ret = mipi_dbi_spi_init(spi, &db->dbi, NULL);
+       if (ret)
+               return dev_err_probe(dev, ret, "MIPI DBI init failed\n");
+
+       endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+       if (!endpoint) {
+               dev_err(dev, "failed to get endpoint\n");
+               return -ENODEV;
+       }
+
+       dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+       if (!dsi_host_node) {
+               dev_err(dev, "failed to get remote port parent\n");
+               goto put_endpoint;
+       }
+
+       dsi_host = of_find_mipi_dsi_host_by_node(dsi_host_node);
+       if (!dsi_host) {
+               dev_err(dev, "failed to find dsi host\n");
+               goto put_host;
+       }
+
+       info.node = of_graph_get_remote_port(endpoint);
+       if (!info.node) {
+               dev_err(dev, "failed to get remote port node\n");
+               ret = -ENODEV;
+               goto put_host;
+       }
+
+       db->dsi_dev = devm_mipi_dsi_device_register_full(dev, dsi_host, &info);
+       if (IS_ERR(db->dsi_dev)) {
+               dev_err(dev, "failed to register dsi device: %ld\n",
+                       PTR_ERR(db->dsi_dev));
+               ret = PTR_ERR(db->dsi_dev);
+               goto put_host;
+       }
+
+       db->dsi_dev->lanes = 2;
+       db->dsi_dev->format = MIPI_DSI_FMT_RGB888;
+       db->dsi_dev->mode_flags = MIPI_DSI_MODE_VIDEO | 
MIPI_DSI_MODE_VIDEO_BURST |
+                         MIPI_DSI_MODE_LPM | MIPI_DSI_MODE_NO_EOT_PACKET;
+
+       drm_panel_init(&db->panel, dev, &ams495qa01_drm_funcs,
+                      DRM_MODE_CONNECTOR_DSI);
+
+       ret = ams495qa01_backlight_register(db);
+       if (ret < 0)
+               return ret;
+
+       drm_panel_add(&db->panel);
+
+       ret = devm_mipi_dsi_attach(dev, db->dsi_dev);
+       if (ret < 0) {
+               dev_err(dev, "mipi_dsi_attach failed: %d\n", ret);
+               drm_panel_remove(&db->panel);
+               return ret;
+       }
+
+       of_node_put(dsi_host_node);
+       of_node_put(endpoint);
+       return 0;
+
+put_host:
+       of_node_put(dsi_host_node);
+
+put_endpoint:
+       of_node_put(endpoint);
+       return -ENODEV;
+}
+
+static void ams495qa01_remove(struct spi_device *spi)
+{
+       struct ams495qa01 *db = spi_get_drvdata(spi);
+
+       drm_panel_remove(&db->panel);
+}
+
+static const struct of_device_id ams495qa01_match[] = {
+       { .compatible = "samsung,ams495qa01", },
+       {},
+};
+MODULE_DEVICE_TABLE(of, ams495qa01_match);
+
+static const struct spi_device_id ams495qa01_ids[] = {
+       { "ams495qa01", 0 },
+       {},
+};
+MODULE_DEVICE_TABLE(spi, ams495qa01_ids);
+
+static struct spi_driver ams495qa01_driver = {
+       .probe          = ams495qa01_probe,
+       .remove         = ams495qa01_remove,
+       .id_table       = ams495qa01_ids,
+       .driver         = {
+               .name   = "ams495qa01-panel",
+               .of_match_table = ams495qa01_match,
+       },
+};
+module_spi_driver(ams495qa01_driver);
+
+MODULE_AUTHOR("Chris Morgan <macromor...@hotmail.com>");
+MODULE_DESCRIPTION("Samsung ams495qa01 panel driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1

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