Add a driver that will work with most MIPI DBI compatible SPI panels.
This avoids adding a driver for every new MIPI DBI compatible controller
that is to be used by Linux. The 'compatible' Device Tree property with
a '.bin' suffix will be used to load a firmware file that contains the
controller configuration.

Example (driver will load sainsmart18.bin):

display@0 {
        compatible = "sainsmart18", "panel-mipi-dbi-spi";
        reg = <0>;
        reset-gpios = <&gpio 25 0>;
        dc-gpios = <&gpio 24 0>;
};

v2:
- Drop model property and use compatible instead (Rob)
- Add wiki entry in MAINTAINERS

Signed-off-by: Noralf Trønnes <nor...@tronnes.org>
---
 MAINTAINERS                            |   8 +
 drivers/gpu/drm/panel/Kconfig          |  11 +
 drivers/gpu/drm/panel/Makefile         |   1 +
 drivers/gpu/drm/panel/panel-mipi-dbi.c | 394 +++++++++++++++++++++++++
 4 files changed, 414 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-mipi-dbi.c

diff --git a/MAINTAINERS b/MAINTAINERS
index d03ad8da1f36..8baa98723bdc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6047,6 +6047,14 @@ T:       git git://anongit.freedesktop.org/drm/drm-misc
 F:     Documentation/devicetree/bindings/display/multi-inno,mi0283qt.txt
 F:     drivers/gpu/drm/tiny/mi0283qt.c
 
+DRM DRIVER FOR MIPI DBI compatible panels
+M:     Noralf Trønnes <nor...@tronnes.org>
+S:     Maintained
+W:     https://github.com/notro/panel-mipi-dbi/wiki
+T:     git git://anongit.freedesktop.org/drm/drm-misc
+F:     Documentation/devicetree/bindings/display/panel/panel-mipi-dbi-spi.yaml
+F:     drivers/gpu/drm/panel/panel-mipi-dbi.c
+
 DRM DRIVER FOR MSM ADRENO GPU
 M:     Rob Clark <robdcl...@gmail.com>
 M:     Sean Paul <s...@poorly.run>
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 434c2861bb40..1851cda5f877 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -274,6 +274,17 @@ config DRM_PANEL_LG_LG4573
          Say Y here if you want to enable support for LG4573 RGB panel.
          To compile this driver as a module, choose M here.
 
+config DRM_PANEL_MIPI_DBI
+       tristate "MIPI DBI compatible panel"
+       depends on SPI
+       depends on BACKLIGHT_CLASS_DEVICE
+       depends on DRM_KMS_HELPER
+       select DRM_KMS_CMA_HELPER
+       select DRM_MIPI_DBI
+       help
+         Say Y here if you want to enable support for MIPI DBI compatible 
panels.
+         To compile this driver as a module, choose M here.
+
 config DRM_PANEL_NEC_NL8048HL11
        tristate "NEC NL8048HL11 RGB panel"
        depends on GPIOLIB && OF && SPI
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index d99fbbce49d1..a90c30459964 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK050H3146W) += 
panel-leadtek-ltk050h3146w.o
 obj-$(CONFIG_DRM_PANEL_LEADTEK_LTK500HD1829) += panel-leadtek-ltk500hd1829.o
 obj-$(CONFIG_DRM_PANEL_LG_LB035Q02) += panel-lg-lb035q02.o
 obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
+obj-$(CONFIG_DRM_PANEL_MIPI_DBI) += panel-mipi-dbi.o
 obj-$(CONFIG_DRM_PANEL_NEC_NL8048HL11) += panel-nec-nl8048hl11.o
 obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35510) += panel-novatek-nt35510.o
 obj-$(CONFIG_DRM_PANEL_NOVATEK_NT35950) += panel-novatek-nt35950.o
diff --git a/drivers/gpu/drm/panel/panel-mipi-dbi.c 
b/drivers/gpu/drm/panel/panel-mipi-dbi.c
new file mode 100644
index 000000000000..6e3dc2de21d2
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-mipi-dbi.c
@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DRM driver for MIPI DBI compatible display panels
+ *
+ * Copyright 2022 Noralf Trønnes
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/firmware.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_mipi_dbi.h>
+#include <drm/drm_modeset_helper.h>
+#include <video/mipi_display.h>
+
+static const u8 panel_mipi_dbi_magic[15] = { 'M', 'I', 'P', 'I', ' ', 'D', 
'B', 'I',
+                                            0, 0, 0, 0, 0, 0, 0 };
+
+/*
+ * The display panel configuration is stored in a firmware file. The Device 
Tree 'compatible'
+ * property value with a '.bin' suffix is passed to request_firmware() to 
fetch this file.
+ */
+struct panel_mipi_dbi_config {
+       /* Magic string: panel_mipi_dbi_magic */
+       u8 magic[15];
+
+       /* Config file format version */
+       u8 file_format_version;
+
+       /* Width in pixels */
+       __be16 width;
+       /* Height in pixels */
+       __be16 height;
+
+       /* Width in millimeters (optional) */
+       __be16 width_mm;
+       /* Height in millimeters (optional) */
+       __be16 height_mm;
+
+       /* X-axis panel offset */
+       __be16 x_offset;
+       /* Y-axis panel offset */
+       __be16 y_offset;
+
+       /* 4 pad bytes, must be zero */
+       u8 pad[4];
+
+       /*
+        * Optional MIPI commands to execute when the display pipeline is 
enabled.
+        * This can be used to configure the display controller.
+        *
+        * The commands are stored in a byte array with the format:
+        *     command, num_parameters, [ parameter, ...], command, ...
+        *
+        * Some commands require a pause before the next command can be 
received.
+        * Inserting a delay in the command sequence is done by using the NOP 
command with one
+        * parameter: delay in miliseconds (the No Operation command is part of 
the MIPI Display
+        * Command Set where it has no parameters).
+        *
+        * Example:
+        *     command 0x11
+        *     sleep 120ms
+        *     command 0xb1 parameters 0x01, 0x2c, 0x2d
+        *     command 0x29
+        *
+        * Byte sequence:
+        *     0x11 0x00
+        *     0x00 0x01 0x78
+        *     0xb1 0x03 0x01 0x2c 0x2d
+        *     0x29 0x00
+        */
+       u8 commands[];
+};
+
+struct panel_mipi_dbi_commands {
+       const u8 *buf;
+       size_t len;
+};
+
+static void panel_mipi_dbi_enable(struct drm_simple_display_pipe *pipe,
+                                 struct drm_crtc_state *crtc_state,
+                                 struct drm_plane_state *plane_state)
+{
+       struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);
+       struct panel_mipi_dbi_commands *commands = dbidev->driver_private;
+       struct mipi_dbi *dbi = &dbidev->dbi;
+       unsigned int i = 0;
+       int ret, idx;
+
+       if (!drm_dev_enter(pipe->crtc.dev, &idx))
+               return;
+
+       drm_dbg(pipe->crtc.dev, "\n");
+
+       ret = mipi_dbi_poweron_conditional_reset(dbidev);
+       if (ret < 0)
+               goto out_exit;
+       if (ret == 1)
+               goto out_enable;
+
+       if (!commands)
+               goto out_enable;
+
+       while (i < commands->len) {
+               u8 command = commands->buf[i++];
+               u8 num_parameters = commands->buf[i++];
+               const u8 *parameters = &commands->buf[i];
+
+               if (command == 0x00 && num_parameters == 1)
+                       msleep(parameters[0]);
+               else if (num_parameters)
+                       mipi_dbi_command_stackbuf(dbi, command, parameters, 
num_parameters);
+               else
+                       mipi_dbi_command(dbi, command);
+
+               i += num_parameters;
+       }
+
+out_enable:
+       mipi_dbi_enable_flush(dbidev, crtc_state, plane_state);
+out_exit:
+       drm_dev_exit(idx);
+}
+
+static const struct drm_simple_display_pipe_funcs panel_mipi_dbi_pipe_funcs = {
+       .enable = panel_mipi_dbi_enable,
+       .disable = mipi_dbi_pipe_disable,
+       .update = mipi_dbi_pipe_update,
+};
+
+DEFINE_DRM_GEM_CMA_FOPS(panel_mipi_dbi_fops);
+
+static const struct drm_driver panel_mipi_dbi_driver = {
+       .driver_features        = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+       .fops                   = &panel_mipi_dbi_fops,
+       DRM_GEM_CMA_DRIVER_OPS_VMAP,
+       .debugfs_init           = mipi_dbi_debugfs_init,
+       .name                   = "panel-mipi-dbi",
+       .desc                   = "MIPI DBI compatible display panel",
+       .date                   = "20220103",
+       .major                  = 1,
+       .minor                  = 0,
+};
+
+static int panel_mipi_dbi_parse_config(struct mipi_dbi_dev *dbidev,
+                                      struct drm_display_mode *mode,
+                                      const struct firmware *fw)
+{
+       const struct panel_mipi_dbi_config *config = (struct 
panel_mipi_dbi_config *)fw->data;
+       unsigned int width, height, x_offset, y_offset;
+       struct panel_mipi_dbi_commands *commands;
+       struct drm_device *drm = &dbidev->drm;
+       struct device *dev = dbidev->drm.dev;
+       size_t size = fw->size, commands_len;
+       unsigned int i = 0;
+
+       if (size < sizeof(*config)) {
+               dev_err(dev, "config: file size=%zu is too small\n", size);
+               return -EINVAL;
+       }
+
+       if (memcmp(config->magic, panel_mipi_dbi_magic, sizeof(config->magic))) 
{
+               dev_err(dev, "config: Bad magic: %15ph\n", config->magic);
+               return -EINVAL;
+       }
+
+       if (config->file_format_version != 1) {
+               dev_err(dev, "config: version=%u is not supported\n", 
config->file_format_version);
+               return -EINVAL;
+       }
+
+       width = be16_to_cpu(config->width);
+       height = be16_to_cpu(config->height);
+       x_offset = be16_to_cpu(config->x_offset);
+       y_offset = be16_to_cpu(config->y_offset);
+
+       drm_dbg(drm, "size=%zu version=%u\n", size, 
config->file_format_version);
+       drm_dbg(drm, "width=%u height=%u\n", width, height);
+       drm_dbg(drm, "x_offset=%u y_offset=%u\n", x_offset, y_offset);
+
+       if (width && height) {
+               struct drm_display_mode simple_mode = {
+                       DRM_SIMPLE_MODE(width, height, 
be16_to_cpu(config->width_mm),
+                                       be16_to_cpu(config->height_mm))
+               };
+
+               *mode = simple_mode;
+       } else {
+               dev_err(dev, "config: width or height can't be zero\n");
+               return -EINVAL;
+       }
+
+       dbidev->left_offset = x_offset;
+       dbidev->top_offset = y_offset;
+
+       commands_len = size - sizeof(*config);
+       if (!commands_len)
+               return 0;
+
+       while ((i + 1) < commands_len) {
+               u8 command = config->commands[i++];
+               u8 num_parameters = config->commands[i++];
+               const u8 *parameters = &config->commands[i];
+
+               i += num_parameters;
+               if (i > commands_len) {
+                       dev_err(dev, "config: command=0x%02x num_parameters=%u 
overflows\n",
+                               command, num_parameters);
+                       return -EINVAL;
+               }
+
+               if (command == 0x00 && num_parameters == 1)
+                       drm_dbg(drm, "sleep %ums\n", parameters[0]);
+               else
+                       drm_dbg(drm, "command %02x %*ph\n", command, 
num_parameters, parameters);
+       }
+
+       if (i != commands_len) {
+               dev_err(dev, "config: malformed command array\n");
+               return -EINVAL;
+       }
+
+       commands = devm_kzalloc(dev, sizeof(*commands), GFP_KERNEL);
+       if (!commands)
+               return -ENOMEM;
+
+       commands->len = commands_len;
+       commands->buf = devm_kmemdup(dev, config->commands, commands->len, 
GFP_KERNEL);
+       if (!commands->buf)
+               return -ENOMEM;
+
+       dbidev->driver_private = commands;
+
+       return 0;
+}
+
+static int panel_mipi_dbi_spi_probe(struct spi_device *spi)
+{
+       struct device *dev = &spi->dev;
+       struct drm_display_mode mode;
+       struct mipi_dbi_dev *dbidev;
+       const struct firmware *fw;
+       const char *compatible;
+       struct drm_device *drm;
+       struct property *prop;
+       bool fw_found = false;
+       struct mipi_dbi *dbi;
+       struct gpio_desc *dc;
+       char fw_name[40];
+       int ret;
+
+       dbidev = devm_drm_dev_alloc(dev, &panel_mipi_dbi_driver, struct 
mipi_dbi_dev, drm);
+       if (IS_ERR(dbidev))
+               return PTR_ERR(dbidev);
+
+       dbi = &dbidev->dbi;
+       drm = &dbidev->drm;
+
+       of_property_for_each_string(dev->of_node, "compatible", prop, 
compatible) {
+               snprintf(fw_name, sizeof(fw_name), "%s.bin", compatible);
+
+               ret = firmware_request_nowarn(&fw, fw_name, dev);
+               if (ret) {
+                       drm_dbg(drm, "No config file found for compatible: '%s' 
(error=%d)\n",
+                               compatible, ret);
+                       continue;
+               }
+
+               ret = panel_mipi_dbi_parse_config(dbidev, &mode, fw);
+               release_firmware(fw);
+               if (ret)
+                       return ret;
+
+               fw_found = true;
+               break;
+       }
+
+       if (!fw_found) {
+               dev_err(dev, "No config file found\n");
+               return -ENOENT;
+       }
+
+       dbidev->regulator = devm_regulator_get(dev, "power");
+       if (IS_ERR(dbidev->regulator))
+               return dev_err_probe(dev, PTR_ERR(dbidev->regulator),
+                                    "Failed to get regulator 'power'\n");
+
+       dbi->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+       if (IS_ERR(dbi->reset))
+               return dev_err_probe(dev, PTR_ERR(dbi->reset), "Failed to get 
GPIO 'reset'\n");
+
+       dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW);
+       if (IS_ERR(dc))
+               return dev_err_probe(dev, PTR_ERR(dc), "Failed to get GPIO 
'dc'\n");
+
+       dbidev->backlight = devm_of_find_backlight(dev);
+       if (IS_ERR(dbidev->backlight))
+               return dev_err_probe(dev, PTR_ERR(dbidev->backlight), "Failed 
to get backlight\n");
+
+       ret = mipi_dbi_spi_init(spi, dbi, dc);
+       if (ret)
+               return ret;
+
+       if (device_property_present(dev, "write-only"))
+               dbi->read_commands = NULL;
+
+       ret = mipi_dbi_dev_init(dbidev, &panel_mipi_dbi_pipe_funcs, &mode, 0);
+       if (ret)
+               return ret;
+
+       drm_mode_config_reset(drm);
+
+       ret = drm_dev_register(drm, 0);
+       if (ret)
+               return ret;
+
+       spi_set_drvdata(spi, drm);
+
+       drm_fbdev_generic_setup(drm, 0);
+
+       return 0;
+}
+
+static int panel_mipi_dbi_spi_remove(struct spi_device *spi)
+{
+       struct drm_device *drm = spi_get_drvdata(spi);
+
+       drm_dev_unplug(drm);
+       drm_atomic_helper_shutdown(drm);
+
+       return 0;
+}
+
+static void panel_mipi_dbi_spi_shutdown(struct spi_device *spi)
+{
+       drm_atomic_helper_shutdown(spi_get_drvdata(spi));
+}
+
+static int __maybe_unused panel_mipi_dbi_pm_suspend(struct device *dev)
+{
+       return drm_mode_config_helper_suspend(dev_get_drvdata(dev));
+}
+
+static int __maybe_unused panel_mipi_dbi_pm_resume(struct device *dev)
+{
+       drm_mode_config_helper_resume(dev_get_drvdata(dev));
+
+       return 0;
+}
+
+static const struct dev_pm_ops panel_mipi_dbi_pm_ops = {
+       SET_SYSTEM_SLEEP_PM_OPS(panel_mipi_dbi_pm_suspend, 
panel_mipi_dbi_pm_resume)
+};
+
+static const struct of_device_id panel_mipi_dbi_spi_of_match[] = {
+       { .compatible = "panel-mipi-dbi-spi" },
+       {},
+};
+MODULE_DEVICE_TABLE(of, panel_mipi_dbi_spi_of_match);
+
+static const struct spi_device_id panel_mipi_dbi_spi_id[] = {
+       { "panel-mipi-dbi-spi", 0 },
+       { },
+};
+MODULE_DEVICE_TABLE(spi, panel_mipi_dbi_spi_id);
+
+static struct spi_driver panel_mipi_dbi_spi_driver = {
+       .driver = {
+               .name = "panel-mipi-dbi-spi",
+               .owner = THIS_MODULE,
+               .of_match_table = panel_mipi_dbi_spi_of_match,
+               .pm = &panel_mipi_dbi_pm_ops,
+       },
+       .id_table = panel_mipi_dbi_spi_id,
+       .probe = panel_mipi_dbi_spi_probe,
+       .remove = panel_mipi_dbi_spi_remove,
+       .shutdown = panel_mipi_dbi_spi_shutdown,
+};
+module_spi_driver(panel_mipi_dbi_spi_driver);
+
+MODULE_DESCRIPTION("MIPI DBI compatible display panel driver");
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");
-- 
2.33.0

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