[PATCH 4/4] video: Add MIPI DBI compatible SPI driver

[Philipp Zabel <p.zabel@pengutronix.de>]

Port the panel-mipi-dbi driver from the Linux kernel. It works 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 Barebox. 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";
...
};

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/video/Kconfig          |  12 ++
 drivers/video/Makefile         |   1 +
 drivers/video/panel-mipi-dbi.c | 330 +++++++++++++++++++++++++++++++++
 3 files changed, 343 insertions(+)
 create mode 100644 drivers/video/panel-mipi-dbi.c

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 01bdaf47bfca..0e710bb25f79 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -198,4 +198,16 @@ config DRIVER_VIDEO_PANEL_ILITEK_ILI9341
 	  QVGA (240x320) RGB panels. support serial & parallel rgb
 	  interface.
 
+config DRIVER_VIDEO_PANEL_MIPI_DBI
+	tristate "DRM support for MIPI DBI compatible panels"
+	depends on OFTREE && SPI
+	select DRIVER_VIDEO_MIPI_DBI
+	select FIRMWARE
+	select VIDEO_VPL
+	help
+          Say Y here if you want to enable support for MIPI DBI compatible
+          panels. The controller command setup can be provided using a
+          firmware file. For more information see
+          https://github.com/notro/panel-mipi-dbi/wiki.
+
 endif
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index d50d2d3ba562..7718b63f448a 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_DRIVER_VIDEO_TC358767) += tc358767.o
 obj-$(CONFIG_DRIVER_VIDEO_SIMPLE_PANEL) += simple-panel.o
 obj-$(CONFIG_DRIVER_VIDEO_MIPI_DBI) += mipi_dbi.o
 obj-$(CONFIG_DRIVER_VIDEO_PANEL_ILITEK_ILI9341) += panel-ilitek-ili9341.o
+obj-$(CONFIG_DRIVER_VIDEO_PANEL_MIPI_DBI) += panel-mipi-dbi.o
 
 obj-$(CONFIG_DRIVER_VIDEO_ATMEL) += atmel_lcdfb.o atmel_lcdfb_core.o
 obj-$(CONFIG_DRIVER_VIDEO_ATMEL_HLCD) += atmel_hlcdfb.o atmel_lcdfb_core.o
diff --git a/drivers/video/panel-mipi-dbi.c b/drivers/video/panel-mipi-dbi.c
new file mode 100644
index 000000000000..ac6f585be32c
--- /dev/null
+++ b/drivers/video/panel-mipi-dbi.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DRM driver for MIPI DBI compatible display panels
+ *
+ * Copyright 2022 Noralf Trønnes
+ */
+
+#include <clock.h>
+#include <common.h>
+#include <fb.h>
+#include <firmware.h>
+#include <gpiod.h>
+#include <linux/printk.h>
+#include <of.h>
+#include <regulator.h>
+#include <spi/spi.h>
+
+#include <video/backlight.h>
+#include <video/mipi_dbi.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 controller 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;
+
+	/*
+	 * MIPI commands to execute when the display pipeline is enabled.
+	 * This is 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 struct panel_mipi_dbi_commands *
+panel_mipi_dbi_check_commands(struct device *dev, const struct firmware *fw)
+{
+	const struct panel_mipi_dbi_config *config = (struct panel_mipi_dbi_config *)fw->data;
+	struct panel_mipi_dbi_commands *commands;
+	size_t size = fw->size, commands_len;
+	unsigned int i = 0;
+
+	if (size < sizeof(*config) + 2) { /* At least 1 command */
+		dev_err(dev, "config: file size=%zu is too small\n", size);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (memcmp(config->magic, panel_mipi_dbi_magic, sizeof(config->magic))) {
+		dev_err(dev, "config: Bad magic: %15ph\n", config->magic);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (config->file_format_version != 1) {
+		dev_err(dev, "config: version=%u is not supported\n", config->file_format_version);
+		return ERR_PTR(-EINVAL);
+	}
+
+	dev_dbg(dev, "size=%zu version=%u\n", size, config->file_format_version);
+
+	commands_len = size - sizeof(*config);
+
+	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 ERR_PTR(-EINVAL);
+		}
+
+		if (command == 0x00 && num_parameters == 1)
+			dev_dbg(dev, "sleep %ums\n", parameters[0]);
+		else
+			dev_dbg(dev, "command %02x %*ph\n",
+				command, num_parameters, parameters);
+	}
+
+	if (i != commands_len) {
+		dev_err(dev, "config: malformed command array\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	commands = kzalloc(sizeof(*commands), GFP_KERNEL);
+	if (!commands)
+		return ERR_PTR(-ENOMEM);
+
+	commands->len = commands_len;
+	commands->buf = kmemdup(config->commands, commands->len, GFP_KERNEL);
+	if (!commands->buf)
+		return ERR_PTR(-ENOMEM);
+
+	return commands;
+}
+
+static struct panel_mipi_dbi_commands *panel_mipi_dbi_commands_from_fw(struct device *dev)
+{
+	struct panel_mipi_dbi_commands *commands;
+	const struct firmware *fw;
+	const char *compatible;
+	char fw_name[40];
+	int ret;
+
+	ret = of_property_read_string_index(dev->of_node, "compatible", 0, &compatible);
+	if (ret)
+		return ERR_PTR(ret);
+
+	snprintf(fw_name, sizeof(fw_name), "%s.bin", compatible);
+	ret = request_firmware(&fw, fw_name, dev);
+	if (ret) {
+		dev_err(dev, "No config file found for compatible '%s' (error=%d)\n",
+			compatible, ret);
+
+		return ERR_PTR(ret);
+	}
+
+	commands = panel_mipi_dbi_check_commands(dev, fw);
+	release_firmware(fw);
+
+	return commands;
+}
+
+static void panel_mipi_dbi_commands_execute(struct mipi_dbi *dbi,
+					    struct panel_mipi_dbi_commands *commands)
+{
+	unsigned int i = 0;
+
+	if (!commands)
+		return;
+
+	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)
+			mdelay(parameters[0]);
+		else if (num_parameters)
+			mipi_dbi_command_stackbuf(dbi, command, parameters, num_parameters);
+		else
+			mipi_dbi_command(dbi, command);
+
+		i += num_parameters;
+	}
+}
+
+static void panel_mipi_dbi_enable(struct fb_info *info)
+{
+	struct mipi_dbi_dev *dbidev = container_of(info, struct mipi_dbi_dev, info);
+	struct mipi_dbi *dbi = &dbidev->dbi;
+	int ret;
+
+	if (!info->mode) {
+		dev_err(dbidev->dev, "No valid mode found\n");
+		return;
+	}
+
+	if (dbidev->backlight_node && !dbidev->backlight) {
+		dbidev->backlight = of_backlight_find(dbidev->backlight_node);
+		if (!dbidev->backlight)
+			dev_err(dbidev->dev, "No backlight found\n");
+	}
+
+	if (!dbidev->driver_private) {
+		dbidev->driver_private = panel_mipi_dbi_commands_from_fw(dbidev->dev);
+		if (IS_ERR(dbidev->driver_private)) {
+			dbidev->driver_private = NULL;
+			return;
+		}
+	}
+
+	ret = mipi_dbi_poweron_conditional_reset(dbidev);
+	if (ret < 0)
+		return;
+	if (!ret)
+		panel_mipi_dbi_commands_execute(dbi, dbidev->driver_private);
+
+	mipi_dbi_enable_flush(dbidev, info);
+}
+
+
+static struct fb_ops panel_mipi_dbi_ops = {
+	.fb_enable = panel_mipi_dbi_enable,
+	.fb_disable = mipi_dbi_fb_disable,
+	.fb_flush = mipi_dbi_fb_flush,
+};
+
+
+static int panel_mipi_dbi_get_mode(struct mipi_dbi_dev *dbidev, struct fb_videomode *mode)
+{
+	struct device *dev = dbidev->dev;
+	int ret;
+
+	ret = of_get_display_timing(dev->of_node, "panel-timing", mode);
+	if (ret) {
+		dev_err(dev, "%pOF: failed to get panel-timing (error=%d)\n", dev->of_node, ret);
+		return ret;
+	}
+
+	/*
+	 * Make sure width and height are set and that only back porch and
+	 * pixelclock are set in the other timing values. Also check that
+	 * width and height don't exceed the 16-bit value specified by MIPI DCS.
+	 */
+	if (!mode->xres || !mode->yres || mode->display_flags ||
+	    mode->right_margin || mode->hsync_len || (mode->left_margin + mode->xres) > 0xffff ||
+	    mode->lower_margin || mode->vsync_len || (mode->upper_margin + mode->yres) > 0xffff) {
+		dev_err(dev, "%pOF: panel-timing out of bounds\n", dev->of_node);
+		return -EINVAL;
+	}
+
+	/* The driver doesn't use the pixel clock but it is mandatory so fake one if not set */
+	if (!mode->pixclock) {
+		mode->pixclock =
+			(mode->left_margin + mode->xres + mode->right_margin + mode->hsync_len) *
+			(mode->upper_margin + mode->yres + mode->lower_margin + mode->vsync_len) *
+			60 / 1000;
+	}
+
+	return 0;
+}
+
+static int panel_mipi_dbi_spi_probe(struct device *dev)
+{
+	struct mipi_dbi_dev *dbidev;
+	struct spi_device *spi = to_spi_device(dev);
+	struct mipi_dbi *dbi;
+	struct fb_info *info;
+	int dc;
+	int ret;
+
+	dbidev = kzalloc(sizeof(*dbidev), GFP_KERNEL);
+	if (!dbidev)
+		return -ENOMEM;
+
+	dbidev->dev = dev;
+	dbi = &dbidev->dbi;
+	info = &dbidev->info;
+
+	ret = panel_mipi_dbi_get_mode(dbidev, &dbidev->mode);
+	if (ret)
+		return ret;
+
+	dbidev->regulator = regulator_get(dev, "power");
+	if (IS_ERR(dbidev->regulator))
+		return dev_err_probe(dev, PTR_ERR(dbidev->regulator),
+				     "Failed to get regulator 'power'\n");
+
+	dbidev->io_regulator = regulator_get(dev, "io");
+	if (IS_ERR(dbidev->io_regulator))
+		return dev_err_probe(dev, PTR_ERR(dbidev->io_regulator),
+				     "Failed to get regulator 'io'\n");
+
+	dbidev->backlight_node = of_parse_phandle(dev->of_node, "backlight", 0);
+
+	dbi->reset = gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (dbi->reset < 0 && dbi->reset != -ENOENT)
+		return dev_err_probe(dev, dbi->reset, "Failed to get GPIO 'reset'\n");
+
+	dc = gpiod_get(dev, "dc", GPIOD_OUT_LOW);
+	if (dc < 0 && dc != -ENOENT)
+		return dev_err_probe(dev, dc, "Failed to get GPIO 'dc'\n");
+
+	ret = mipi_dbi_spi_init(spi, dbi, dc);
+	if (ret)
+		return ret;
+
+	ret = mipi_dbi_dev_init(dbidev, &panel_mipi_dbi_ops, &dbidev->mode);
+	if (ret)
+		return ret;
+
+	ret = register_framebuffer(info);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to register framebuffer\n");
+
+	return 0;
+}
+
+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 struct driver panel_mipi_dbi_spi_driver = {
+	.name = "panel-mipi-dbi-spi",
+	.probe = panel_mipi_dbi_spi_probe,
+	.of_compatible = DRV_OF_COMPAT(panel_mipi_dbi_spi_of_match),
+};
+device_spi_driver(panel_mipi_dbi_spi_driver);
+
+MODULE_DESCRIPTION("MIPI DBI compatible display panel driver");
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");
-- 
2.39.2