drm/tinydrm: add support for LEGO MINDSTORMS EV3 LCD

LEGO MINDSTORMS EV3 has an LCD with a ST7586 controller. This adds a new
module for the ST7586 controller with parameters for the LEGO MINDSTORMS
EV3 LCD display.
Signed-off-by: David Lechner <david@lechnology.com>
Reviewed-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1502127581-10517-4-git-send-email-david@lechnology.com

MAINTAINERS

@@ -4380,6 +4380,12 @@ S:	Orphan / Obsolete
 F:	drivers/gpu/drm/sis/
 F:	include/uapi/drm/sis_drm.h
 
+DRM DRIVER FOR SITRONIX ST7586 PANELS
+M:	David Lechner <david@lechnology.com>
+S:	Maintained
+F:	drivers/gpu/drm/tinydrm/st7586.c
+F:	Documentation/devicetree/bindings/display/st7586.txt
+
 DRM DRIVER FOR TDFX VIDEO CARDS
 S:	Orphan / Obsolete
 F:	drivers/gpu/drm/tdfx/

drivers/gpu/drm/tinydrm/Kconfig

@@ -32,3 +32,13 @@ config TINYDRM_REPAPER
 	  2.71" TFT EPD Panel (E2271CS021)
 
 	  If M is selected the module will be called repaper.
+
+config TINYDRM_ST7586
+	tristate "DRM support for Sitronix ST7586 display panels"
+	depends on DRM_TINYDRM && SPI
+	select TINYDRM_MIPI_DBI
+	help
+	  DRM driver for the following Sitronix ST7586 panels:
+	  * LEGO MINDSTORMS EV3
+
+	  If M is selected the module will be called st7586.

drivers/gpu/drm/tinydrm/Makefile

@@ -6,3 +6,4 @@ obj-$(CONFIG_TINYDRM_MIPI_DBI)		+= mipi-dbi.o
 # Displays
 obj-$(CONFIG_TINYDRM_MI0283QT)		+= mi0283qt.o
 obj-$(CONFIG_TINYDRM_REPAPER)		+= repaper.o
+obj-$(CONFIG_TINYDRM_ST7586)		+= st7586.o

drivers/gpu/drm/tinydrm/st7586.c

+/*
+ * DRM driver for Sitronix ST7586 panels
+ *
+ * Copyright 2017 David Lechner <david@lechnology.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#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/tinydrm/mipi-dbi.h>
+#include <drm/tinydrm/tinydrm-helpers.h>
+
+/* controller-specific commands */
+#define ST7586_DISP_MODE_GRAY	0x38
+#define ST7586_DISP_MODE_MONO	0x39
+#define ST7586_ENABLE_DDRAM	0x3a
+#define ST7586_SET_DISP_DUTY	0xb0
+#define ST7586_SET_PART_DISP	0xb4
+#define ST7586_SET_NLINE_INV	0xb5
+#define ST7586_SET_VOP		0xc0
+#define ST7586_SET_BIAS_SYSTEM	0xc3
+#define ST7586_SET_BOOST_LEVEL	0xc4
+#define ST7586_SET_VOP_OFFSET	0xc7
+#define ST7586_ENABLE_ANALOG	0xd0
+#define ST7586_AUTO_READ_CTRL	0xd7
+#define ST7586_OTP_RW_CTRL	0xe0
+#define ST7586_OTP_CTRL_OUT	0xe1
+#define ST7586_OTP_READ		0xe3
+
+#define ST7586_DISP_CTRL_MX	BIT(6)
+#define ST7586_DISP_CTRL_MY	BIT(7)
+
+/*
+ * The ST7586 controller has an unusual pixel format where 2bpp grayscale is
+ * packed 3 pixels per byte with the first two pixels using 3 bits and the 3rd
+ * pixel using only 2 bits.
+ *
+ * |  D7  |  D6  |  D5  ||      |      || 2bpp |
+ * | (D4) | (D3) | (D2) ||  D1  |  D0  || GRAY |
+ * +------+------+------++------+------++------+
+ * |  1   |  1   |  1   ||  1   |  1   || 0  0 | black
+ * |  1   |  0   |  0   ||  1   |  0   || 0  1 | dark gray
+ * |  0   |  1   |  0   ||  0   |  1   || 1  0 | light gray
+ * |  0   |  0   |  0   ||  0   |  0   || 1  1 | white
+ */
+
+static const u8 st7586_lookup[] = { 0x7, 0x4, 0x2, 0x0 };
+
+static void st7586_xrgb8888_to_gray332(u8 *dst, void *vaddr,
+				       struct drm_framebuffer *fb,
+				       struct drm_clip_rect *clip)
+{
+	size_t len = (clip->x2 - clip->x1) * (clip->y2 - clip->y1);
+	unsigned int x, y;
+	u8 *src, *buf, val;
+
+	buf = kmalloc(len, GFP_KERNEL);
+	if (!buf)
+		return;
+
+	tinydrm_xrgb8888_to_gray8(buf, vaddr, fb, clip);
+	src = buf;
+
+	for (y = clip->y1; y < clip->y2; y++) {
+		for (x = clip->x1; x < clip->x2; x += 3) {
+			val = st7586_lookup[*src++ >> 6] << 5;
+			val |= st7586_lookup[*src++ >> 6] << 2;
+			val |= st7586_lookup[*src++ >> 6] >> 1;
+			*dst++ = val;
+		}
+	}
+
+	kfree(buf);
+}
+
+static int st7586_buf_copy(void *dst, struct drm_framebuffer *fb,
+			   struct drm_clip_rect *clip)
+{
+	struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
+	struct dma_buf_attachment *import_attach = cma_obj->base.import_attach;
+	void *src = cma_obj->vaddr;
+	int ret = 0;
+
+	if (import_attach) {
+		ret = dma_buf_begin_cpu_access(import_attach->dmabuf,
+					       DMA_FROM_DEVICE);
+		if (ret)
+			return ret;
+	}
+
+	st7586_xrgb8888_to_gray332(dst, src, fb, clip);
+
+	if (import_attach)
+		ret = dma_buf_end_cpu_access(import_attach->dmabuf,
+					     DMA_FROM_DEVICE);
+
+	return ret;
+}
+
+static int st7586_fb_dirty(struct drm_framebuffer *fb,
+			   struct drm_file *file_priv, unsigned int flags,
+			   unsigned int color, struct drm_clip_rect *clips,
+			   unsigned int num_clips)
+{
+	struct tinydrm_device *tdev = fb->dev->dev_private;
+	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
+	struct drm_clip_rect clip;
+	int start, end;
+	int ret = 0;
+
+	mutex_lock(&tdev->dirty_lock);
+
+	if (!mipi->enabled)
+		goto out_unlock;
+
+	/* fbdev can flush even when we're not interested */
+	if (tdev->pipe.plane.fb != fb)
+		goto out_unlock;
+
+	tinydrm_merge_clips(&clip, clips, num_clips, flags, fb->width,
+			    fb->height);
+
+	/* 3 pixels per byte, so grow clip to nearest multiple of 3 */
+	clip.x1 = rounddown(clip.x1, 3);
+	clip.x2 = roundup(clip.x2, 3);
+
+	DRM_DEBUG("Flushing [FB:%d] x1=%u, x2=%u, y1=%u, y2=%u\n", fb->base.id,
+		  clip.x1, clip.x2, clip.y1, clip.y2);
+
+	ret = st7586_buf_copy(mipi->tx_buf, fb, &clip);
+	if (ret)
+		goto out_unlock;
+
+	/* Pixels are packed 3 per byte */
+	start = clip.x1 / 3;
+	end = clip.x2 / 3;
+
+	mipi_dbi_command(mipi, MIPI_DCS_SET_COLUMN_ADDRESS,
+			 (start >> 8) & 0xFF, start & 0xFF,
+			 (end >> 8) & 0xFF, (end - 1) & 0xFF);
+	mipi_dbi_command(mipi, MIPI_DCS_SET_PAGE_ADDRESS,
+			 (clip.y1 >> 8) & 0xFF, clip.y1 & 0xFF,
+			 (clip.y2 >> 8) & 0xFF, (clip.y2 - 1) & 0xFF);
+
+	ret = mipi_dbi_command_buf(mipi, MIPI_DCS_WRITE_MEMORY_START,
+				   (u8 *)mipi->tx_buf,
+				   (end - start) * (clip.y2 - clip.y1));
+
+out_unlock:
+	mutex_unlock(&tdev->dirty_lock);
+
+	if (ret)
+		dev_err_once(fb->dev->dev, "Failed to update display %d\n",
+			     ret);
+
+	return ret;
+}
+
+static const struct drm_framebuffer_funcs st7586_fb_funcs = {
+	.destroy	= drm_fb_cma_destroy,
+	.create_handle	= drm_fb_cma_create_handle,
+	.dirty		= st7586_fb_dirty,
+};
+
+void st7586_pipe_enable(struct drm_simple_display_pipe *pipe,
+			struct drm_crtc_state *crtc_state)
+{
+	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
+	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
+	struct drm_framebuffer *fb = pipe->plane.fb;
+	struct device *dev = tdev->drm->dev;
+	int ret;
+	u8 addr_mode;
+
+	DRM_DEBUG_KMS("\n");
+
+	mipi_dbi_hw_reset(mipi);
+	ret = mipi_dbi_command(mipi, ST7586_AUTO_READ_CTRL, 0x9f);
+	if (ret) {
+		dev_err(dev, "Error sending command %d\n", ret);
+		return;
+	}
+
+	mipi_dbi_command(mipi, ST7586_OTP_RW_CTRL, 0x00);
+
+	msleep(10);
+
+	mipi_dbi_command(mipi, ST7586_OTP_READ);
+
+	msleep(20);
+
+	mipi_dbi_command(mipi, ST7586_OTP_CTRL_OUT);
+	mipi_dbi_command(mipi, MIPI_DCS_EXIT_SLEEP_MODE);
+	mipi_dbi_command(mipi, MIPI_DCS_SET_DISPLAY_OFF);
+
+	msleep(50);
+
+	mipi_dbi_command(mipi, ST7586_SET_VOP_OFFSET, 0x00);
+	mipi_dbi_command(mipi, ST7586_SET_VOP, 0xe3, 0x00);
+	mipi_dbi_command(mipi, ST7586_SET_BIAS_SYSTEM, 0x02);
+	mipi_dbi_command(mipi, ST7586_SET_BOOST_LEVEL, 0x04);
+	mipi_dbi_command(mipi, ST7586_ENABLE_ANALOG, 0x1d);
+	mipi_dbi_command(mipi, ST7586_SET_NLINE_INV, 0x00);
+	mipi_dbi_command(mipi, ST7586_DISP_MODE_GRAY);
+	mipi_dbi_command(mipi, ST7586_ENABLE_DDRAM, 0x02);
+
+	switch (mipi->rotation) {
+	default:
+		addr_mode = 0x00;
+		break;
+	case 90:
+		addr_mode = ST7586_DISP_CTRL_MY;
+		break;
+	case 180:
+		addr_mode = ST7586_DISP_CTRL_MX | ST7586_DISP_CTRL_MY;
+		break;
+	case 270:
+		addr_mode = ST7586_DISP_CTRL_MX;
+		break;
+	}
+	mipi_dbi_command(mipi, MIPI_DCS_SET_ADDRESS_MODE, addr_mode);
+
+	mipi_dbi_command(mipi, ST7586_SET_DISP_DUTY, 0x7f);
+	mipi_dbi_command(mipi, ST7586_SET_PART_DISP, 0xa0);
+	mipi_dbi_command(mipi, MIPI_DCS_SET_PARTIAL_AREA, 0x00, 0x00, 0x00, 0x77);
+	mipi_dbi_command(mipi, MIPI_DCS_EXIT_INVERT_MODE);
+
+	msleep(100);
+
+	mipi_dbi_command(mipi, MIPI_DCS_SET_DISPLAY_ON);
+
+	mipi->enabled = true;
+
+	if (fb)
+		fb->funcs->dirty(fb, NULL, 0, 0, NULL, 0);
+}
+
+static void st7586_pipe_disable(struct drm_simple_display_pipe *pipe)
+{
+	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
+	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
+
+	DRM_DEBUG_KMS("\n");
+
+	if (!mipi->enabled)
+		return;
+
+	mipi_dbi_command(mipi, MIPI_DCS_SET_DISPLAY_OFF);
+	mipi->enabled = false;
+}
+
+static const u32 st7586_formats[] = {
+	DRM_FORMAT_XRGB8888,
+};
+
+static int st7586_init(struct device *dev, struct mipi_dbi *mipi,
+		const struct drm_simple_display_pipe_funcs *pipe_funcs,
+		struct drm_driver *driver, const struct drm_display_mode *mode,
+		unsigned int rotation)
+{
+	size_t bufsize = (mode->vdisplay + 2) / 3 * mode->hdisplay;
+	struct tinydrm_device *tdev = &mipi->tinydrm;
+	int ret;
+
+	mutex_init(&mipi->cmdlock);
+
+	mipi->tx_buf = devm_kmalloc(dev, bufsize, GFP_KERNEL);
+	if (!mipi->tx_buf)
+		return -ENOMEM;
+
+	ret = devm_tinydrm_init(dev, tdev, &st7586_fb_funcs, driver);
+	if (ret)
+		return ret;
+
+	ret = tinydrm_display_pipe_init(tdev, pipe_funcs,
+					DRM_MODE_CONNECTOR_VIRTUAL,
+					st7586_formats,
+					ARRAY_SIZE(st7586_formats),
+					mode, rotation);
+	if (ret)
+		return ret;
+
+	tdev->drm->mode_config.preferred_depth = 32;
+	mipi->rotation = rotation;
+
+	drm_mode_config_reset(tdev->drm);
+
+	DRM_DEBUG_KMS("preferred_depth=%u, rotation = %u\n",
+		      tdev->drm->mode_config.preferred_depth, rotation);
+
+	return 0;
+}
+
+static const struct drm_simple_display_pipe_funcs st7586_pipe_funcs = {
+	.enable		= st7586_pipe_enable,
+	.disable	= st7586_pipe_disable,
+	.update		= tinydrm_display_pipe_update,
+	.prepare_fb	= tinydrm_display_pipe_prepare_fb,
+};
+
+static const struct drm_display_mode st7586_mode = {
+	TINYDRM_MODE(178, 128, 37, 27),
+};
+
+DEFINE_DRM_GEM_CMA_FOPS(st7586_fops);
+
+static struct drm_driver st7586_driver = {
+	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME |
+				  DRIVER_ATOMIC,
+	.fops			= &st7586_fops,
+	TINYDRM_GEM_DRIVER_OPS,
+	.lastclose		= tinydrm_lastclose,
+	.debugfs_init		= mipi_dbi_debugfs_init,
+	.name			= "st7586",
+	.desc			= "Sitronix ST7586",
+	.date			= "20170801",
+	.major			= 1,
+	.minor			= 0,
+};
+
+static const struct of_device_id st7586_of_match[] = {
+	{ .compatible = "lego,ev3-lcd" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, st7586_of_match);
+
+static const struct spi_device_id st7586_id[] = {
+	{ "ev3-lcd", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, st7586_id);
+
+static int st7586_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct tinydrm_device *tdev;
+	struct mipi_dbi *mipi;
+	struct gpio_desc *a0;
+	u32 rotation = 0;
+	int ret;
+
+	mipi = devm_kzalloc(dev, sizeof(*mipi), GFP_KERNEL);
+	if (!mipi)
+		return -ENOMEM;
+
+	mipi->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(mipi->reset)) {
+		dev_err(dev, "Failed to get gpio 'reset'\n");
+		return PTR_ERR(mipi->reset);
+	}
+
+	a0 = devm_gpiod_get(dev, "a0", GPIOD_OUT_LOW);
+	if (IS_ERR(a0)) {
+		dev_err(dev, "Failed to get gpio 'a0'\n");
+		return PTR_ERR(a0);
+	}
+
+	device_property_read_u32(dev, "rotation", &rotation);
+
+	ret = mipi_dbi_spi_init(spi, mipi, a0);
+	if (ret)
+		return ret;
+
+	/* Cannot read from this controller via SPI */
+	mipi->read_commands = NULL;
+
+	/*
+	 * we are using 8-bit data, so we are not actually swapping anything,
+	 * but setting mipi->swap_bytes makes mipi_dbi_typec3_command() do the
+	 * right thing and not use 16-bit transfers (which results in swapped
+	 * bytes on little-endian systems and causes out of order data to be
+	 * sent to the display).
+	 */
+	mipi->swap_bytes = true;
+
+	ret = st7586_init(&spi->dev, mipi, &st7586_pipe_funcs, &st7586_driver,
+			  &st7586_mode, rotation);
+	if (ret)
+		return ret;
+
+	tdev = &mipi->tinydrm;
+
+	ret = devm_tinydrm_register(tdev);
+	if (ret)
+		return ret;
+
+	spi_set_drvdata(spi, mipi);
+
+	DRM_DEBUG_DRIVER("Initialized %s:%s @%uMHz on minor %d\n",
+			 tdev->drm->driver->name, dev_name(dev),
+			 spi->max_speed_hz / 1000000,
+			 tdev->drm->primary->index);
+
+	return 0;
+}
+
+static void st7586_shutdown(struct spi_device *spi)
+{
+	struct mipi_dbi *mipi = spi_get_drvdata(spi);
+
+	tinydrm_shutdown(&mipi->tinydrm);
+}
+
+static struct spi_driver st7586_spi_driver = {
+	.driver = {
+		.name = "st7586",
+		.owner = THIS_MODULE,
+		.of_match_table = st7586_of_match,
+	},
+	.id_table = st7586_id,
+	.probe = st7586_probe,
+	.shutdown = st7586_shutdown,
+};
+module_spi_driver(st7586_spi_driver);
+
+MODULE_DESCRIPTION("Sitronix ST7586 DRM driver");
+MODULE_AUTHOR("David Lechner <david@lechnology.com>");
+MODULE_LICENSE("GPL");