[PATCH 3/4] drm/tiny: add simple-dbi driver

[Icenowy Zheng]

Add a driver for generic MIPI DBI panels initialized with MIPI DCS
commands.

Currently a ST7789V-based panel is added to it. This panel has its
configuration pre-programmed into the controller, so no vendor-specific
configuration is needed.

Signed-off-by: Icenowy Zheng <icenowy@xxxxxxxxxx>
---
 drivers/gpu/drm/tiny/Kconfig      |  12 ++
 drivers/gpu/drm/tiny/Makefile     |   1 +
 drivers/gpu/drm/tiny/simple-dbi.c | 244 ++++++++++++++++++++++++++++++
 3 files changed, 257 insertions(+)
 create mode 100644 drivers/gpu/drm/tiny/simple-dbi.c

diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index d31be274a2bd..6cfc57b68a46 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -144,6 +144,18 @@ config TINYDRM_REPAPER
 
 	  If M is selected the module will be called repaper.
 
+config TINYDRM_SIMPLE_DBI
+	tristate "DRM support for generic MIPI DBI panels"
+	depends on DRM && SPI
+	select DRM_KMS_HELPER
+	select DRM_KMS_CMA_HELPER
+	select DRM_MIPI_DBI
+	help
+	  DRM driver for generic DBI panels that are MIPI DCS compatible
+	  and needs no vendor-specific setup commands.
+
+	  If M is selected the module will be called simple-dbi.
+
 config TINYDRM_ST7586
 	tristate "DRM support for Sitronix ST7586 display panels"
 	depends on DRM && SPI
diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
index e09942895c77..2553de651aa3 100644
--- a/drivers/gpu/drm/tiny/Makefile
+++ b/drivers/gpu/drm/tiny/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_TINYDRM_MI0283QT)		+= mi0283qt.o
 obj-$(CONFIG_TINYDRM_REPAPER)		+= repaper.o
 obj-$(CONFIG_TINYDRM_ST7586)		+= st7586.o
 obj-$(CONFIG_TINYDRM_ST7735R)		+= st7735r.o
+obj-$(CONFIG_TINYDRM_SIMPLE_DBI)	+= simple-dbi.o
diff --git a/drivers/gpu/drm/tiny/simple-dbi.c b/drivers/gpu/drm/tiny/simple-dbi.c
new file mode 100644
index 000000000000..2b207e43d500
--- /dev/null
+++ b/drivers/gpu/drm/tiny/simple-dbi.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * DRM driver for display panels with configuration preset and needs only
+ * standard MIPI DCS commands to bring up.
+ *
+ * Copyright (C) 2021 Sipeed
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/dma-buf.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/spi/spi.h>
+#include <video/mipi_display.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>
+
+#define MIPI_DCS_ADDRESS_MODE_BGR		BIT(3)
+#define MIPI_DCS_ADDRESS_MODE_REVERSE		BIT(5)
+#define MIPI_DCS_ADDRESS_MODE_RTL		BIT(6)
+#define MIPI_DCS_ADDRESS_MODE_BTT		BIT(7)
+
+struct simple_dbi_cfg {
+	const struct drm_display_mode mode;
+	unsigned int left_offset;
+	unsigned int top_offset;
+	bool inverted;
+	bool write_only;
+	bool bgr;
+	bool right_to_left;
+	bool bottom_to_top;
+};
+
+struct simple_dbi_priv {
+	struct mipi_dbi_dev dbidev;	/* Must be first for .release() */
+	const struct simple_dbi_cfg *cfg;
+};
+
+static void simple_dbi_pipe_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 simple_dbi_priv *priv = container_of(dbidev,
+						    struct simple_dbi_priv,
+						    dbidev);
+	struct mipi_dbi *dbi = &dbidev->dbi;
+	int ret, idx;
+	u8 addr_mode = 0x00;
+
+	if (!drm_dev_enter(pipe->crtc.dev, &idx))
+		return;
+
+	DRM_DEBUG_KMS("\n");
+
+	ret = mipi_dbi_poweron_reset(dbidev);
+	if (ret)
+		goto out_exit;
+
+	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
+	msleep(5);
+
+	/* Currently tinydrm supports 16bit only now */
+	mipi_dbi_command(dbi, MIPI_DCS_SET_PIXEL_FORMAT,
+			 MIPI_DCS_PIXEL_FMT_16BIT);
+
+	if (priv->cfg->inverted)
+		mipi_dbi_command(dbi, MIPI_DCS_ENTER_INVERT_MODE);
+	else
+		mipi_dbi_command(dbi, MIPI_DCS_EXIT_INVERT_MODE);
+
+	if (priv->cfg->bgr)
+		addr_mode |= MIPI_DCS_ADDRESS_MODE_BGR;
+
+	if (priv->cfg->right_to_left)
+		addr_mode |= MIPI_DCS_ADDRESS_MODE_RTL;
+
+	if (priv->cfg->bottom_to_top)
+		addr_mode |= MIPI_DCS_ADDRESS_MODE_BTT;
+
+	switch (dbidev->rotation) {
+	default:
+		break;
+	case 90:
+		addr_mode ^= MIPI_DCS_ADDRESS_MODE_REVERSE;
+		addr_mode ^= MIPI_DCS_ADDRESS_MODE_RTL;
+		break;
+	case 180:
+		addr_mode ^= MIPI_DCS_ADDRESS_MODE_RTL;
+		addr_mode ^= MIPI_DCS_ADDRESS_MODE_BTT;
+		break;
+	case 270:
+		addr_mode ^= MIPI_DCS_ADDRESS_MODE_REVERSE;
+		addr_mode ^= MIPI_DCS_ADDRESS_MODE_BTT;
+		break;
+	}
+
+	mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, addr_mode);
+
+	mipi_dbi_command(dbi, MIPI_DCS_ENTER_NORMAL_MODE);
+
+	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
+
+	mipi_dbi_enable_flush(dbidev, crtc_state, plane_state);
+out_exit:
+	drm_dev_exit(idx);
+}
+
+static const struct drm_simple_display_pipe_funcs simple_dbi_pipe_funcs = {
+	.enable		= simple_dbi_pipe_enable,
+	.disable	= mipi_dbi_pipe_disable,
+	.update		= mipi_dbi_pipe_update,
+	.prepare_fb	= drm_gem_simple_display_pipe_prepare_fb,
+};
+
+static const struct simple_dbi_cfg zsx154_b1206_cfg = {
+	.mode		= { DRM_SIMPLE_MODE(240, 240, 28, 28) },
+	.inverted	= true,
+	.write_only	= true,
+};
+
+DEFINE_DRM_GEM_CMA_FOPS(simple_dbi_fops);
+
+static const struct drm_driver simple_dbi_driver = {
+	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+	.fops			= &simple_dbi_fops,
+	DRM_GEM_CMA_DRIVER_OPS_VMAP,
+	.debugfs_init		= mipi_dbi_debugfs_init,
+	.name			= "simple-dbi",
+	.desc			= "Generic MIPI-DCS compatible DBI panel",
+	.date			= "20210723",
+	.major			= 1,
+	.minor			= 0,
+};
+
+static const struct of_device_id simple_dbi_of_match[] = {
+	{ .compatible = "zsx,zsx154-b1206", .data = &zsx154_b1206_cfg },
+	{ },
+}
+MODULE_DEVICE_TABLE(of, simple_dbi_of_match);
+
+static int simple_dbi_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	const struct simple_dbi_cfg *cfg;
+	struct mipi_dbi_dev *dbidev;
+	struct simple_dbi_priv *priv;
+	struct drm_device *drm;
+	struct mipi_dbi *dbi;
+	struct gpio_desc *dc;
+	u32 rotation = 0;
+	int ret;
+
+	cfg = device_get_match_data(&spi->dev);
+	if (!cfg)
+		cfg = (void *)spi_get_device_id(spi)->driver_data;
+
+	priv = devm_drm_dev_alloc(dev, &simple_dbi_driver,
+				  struct simple_dbi_priv, dbidev.drm);
+	if (IS_ERR(priv))
+		return PTR_ERR(priv);
+
+	dbidev = &priv->dbidev;
+	priv->cfg = cfg;
+
+	dbi = &dbidev->dbi;
+	drm = &dbidev->drm;
+
+	dbi->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(dbi->reset))
+		return dev_err_probe(dev, PTR_ERR(dbi->reset), "Failed to get reset GPIO\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 D/C GPIO\n");
+
+	dbidev->backlight = devm_of_find_backlight(dev);
+	if (IS_ERR(dbidev->backlight))
+		return PTR_ERR(dbidev->backlight);
+
+	device_property_read_u32(dev, "rotation", &rotation);
+
+	ret = mipi_dbi_spi_init(spi, dbi, dc);
+	if (ret)
+		return ret;
+
+	if (cfg->write_only)
+		dbi->read_commands = NULL;
+
+	ret = mipi_dbi_dev_init(dbidev, &simple_dbi_pipe_funcs, &cfg->mode,
+				rotation);
+	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 simple_dbi_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 simple_dbi_shutdown(struct spi_device *spi)
+{
+	drm_atomic_helper_shutdown(spi_get_drvdata(spi));
+}
+
+static struct spi_driver simple_dbi_spi_driver = {
+	.driver = {
+		.name = "simple-dbi",
+		.of_match_table = simple_dbi_of_match,
+	},
+	.probe = simple_dbi_probe,
+	.remove = simple_dbi_remove,
+	.shutdown = simple_dbi_shutdown,
+};
+module_spi_driver(simple_dbi_spi_driver);
+
+MODULE_DESCRIPTION("Simple DBI panel DRM driver");
+MODULE_AUTHOR("Icenowy Zheng <icenowy@xxxxxxx>");
+MODULE_LICENSE("GPL");
-- 
2.30.2