From 30f2bc6cf91c74c53192c58324981bd4ed446b06 Mon Sep 17 00:00:00 2001
From: Suguru Saito <sg.sgch07@gmail.com>
Date: Mon, 4 Oct 2021 12:22:07 +0900
Subject: [PATCH] drm: add st7586 driver for Sharp Brain 2nd generation SubLCD

---
 drivers/gpu/drm/tiny/brain-st7586.c | 443 ++++++++++++++++++++++++++++
 1 file changed, 443 insertions(+)
 create mode 100644 drivers/gpu/drm/tiny/brain-st7586.c

diff --git a/drivers/gpu/drm/tiny/brain-st7586.c b/drivers/gpu/drm/tiny/brain-st7586.c
new file mode 100644
index 000000000000..ced526ca3cfb
--- /dev/null
+++ b/drivers/gpu/drm/tiny/brain-st7586.c
@@ -0,0 +1,443 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * DRM driver for Sitronix ST7586 panels for Brain 2nd SubLCD
+ *
+ * Copyright 2021 Suguru Saito <sg.sgch07@gmail.com>
+ *
+ * based on st7586.c
+ * Copyright 2017 David Lechner <david@lechnology.com>
+ */
+
+#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_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_mipi_dbi.h>
+#include <drm/drm_rect.h>
+#include <drm/drm_vblank.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_OUTPUT_COM	0xb1
+#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)
+
+#define BRAIN_PAGE_OFFSET	0x28
+
+/*
+ * 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_word(u16 *dst, void *vaddr,
+				       struct drm_framebuffer *fb,
+				       struct drm_rect *clip)
+{
+	size_t len = (clip->x2 - clip->x1) * (clip->y2 - clip->y1);
+	unsigned int x, y;
+	u8 *src, *buf;
+	u16 packed;
+
+	buf = kmalloc(len, GFP_KERNEL);
+	if (!buf)
+		return;
+
+	drm_fb_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*2) {
+			/*
+			 * buf: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, ...
+			 * dst: 210543, 876ba9, ...
+			 */
+			packed = (st7586_lookup[*src++ >> 6] & 0x03) << 8;
+			packed |= st7586_lookup[*src++ >> 6] << 10;
+			packed |= st7586_lookup[*src++ >> 6] << 13;
+			packed |= (st7586_lookup[*src++ >> 6] & 0x03) << 0;
+			packed |= st7586_lookup[*src++ >> 6] << 2;
+			packed |= st7586_lookup[*src++ >> 6] << 5;
+
+			*dst++ = packed;
+		}
+	}
+
+	kfree(buf);
+}
+
+static int st7586_buf_copy(void *dst, struct drm_framebuffer *fb,
+			   struct drm_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_word(dst, src, fb, clip);
+
+	if (import_attach)
+		ret = dma_buf_end_cpu_access(import_attach->dmabuf,
+					     DMA_FROM_DEVICE);
+
+	return ret;
+}
+
+static void st7586_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect)
+{
+	struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev);
+	struct mipi_dbi *dbi = &dbidev->dbi;
+	int start_col, end_col, start_page, end_page, len, idx, ret = 0;
+
+	if (!dbidev->enabled)
+		return;
+
+	if (!drm_dev_enter(fb->dev, &idx))
+		return;
+
+	/* 3 pixels per byte, so grow clip to nearest multiple of 3 */
+	rect->x1 = rounddown(rect->x1, 3);
+	rect->x2 = roundup(rect->x2, 3);
+
+	DRM_DEBUG_KMS("Flushing [FB:%d] " DRM_RECT_FMT "\n", fb->base.id, DRM_RECT_ARG(rect));
+
+	ret = st7586_buf_copy(dbidev->tx_buf, fb, rect);
+	if (ret)
+		goto err_msg;
+
+	/* Pixels are packed 3 per byte */
+	start_col = rect->x1 / 3;
+	end_col = rect->x2 / 3;
+
+	len = (end_col - start_col) * (rect->y2 - rect->y1) / 2;
+
+	/* Write to top-side DDRAM */
+	start_page = rect->y1 + BRAIN_PAGE_OFFSET;
+	end_page = (rect->y2 - rect->y1) / 2 + BRAIN_PAGE_OFFSET;
+	mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS,
+			 (start_col >> 8) & 0xFF, start_col & 0xFF,
+			 (end_col >> 8) & 0xFF, (end_col - 1) & 0xFF);
+	mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS,
+			 (start_page >> 8) & 0xFF, start_page & 0xFF,
+			 (end_page >> 8) & 0xFF, (end_page - 1) & 0xFF);
+
+	ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START,
+				   (u8 *)dbidev->tx_buf, len);
+	if (ret)
+		goto err_msg;
+
+	/* Write to bottom-side DDRAM */
+	start_page = (rect->y2 - rect->y1) / 2 + BRAIN_PAGE_OFFSET;
+	end_page = rect->y2 + BRAIN_PAGE_OFFSET;
+	mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS,
+			 (start_col >> 8) & 0xFF, start_col & 0xFF,
+			 (end_col >> 8) & 0xFF, (end_col - 1) & 0xFF);
+	mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS,
+			 (start_page >> 8) & 0xFF, start_page & 0xFF,
+			 (end_page >> 8) & 0xFF, (end_page - 1) & 0xFF);
+
+	ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START,
+				   ((u8 *)dbidev->tx_buf) + len, len);
+err_msg:
+	if (ret)
+		dev_err_once(fb->dev->dev, "Failed to update display %d\n", ret);
+
+	drm_dev_exit(idx);
+}
+
+static void st7586_pipe_update(struct drm_simple_display_pipe *pipe,
+			       struct drm_plane_state *old_state)
+{
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_crtc *crtc = &pipe->crtc;
+	struct drm_rect rect;
+
+	if (drm_atomic_helper_damage_merged(old_state, state, &rect))
+		st7586_fb_dirty(state->fb, &rect);
+
+	if (crtc->state->event) {
+		spin_lock_irq(&crtc->dev->event_lock);
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		spin_unlock_irq(&crtc->dev->event_lock);
+		crtc->state->event = NULL;
+	}
+}
+
+static void st7586_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 drm_framebuffer *fb = plane_state->fb;
+	struct mipi_dbi *dbi = &dbidev->dbi;
+	struct drm_rect rect = {
+		.x1 = 0,
+		.x2 = fb->width,
+		.y1 = 0,
+		.y2 = fb->height,
+	};
+	int idx, ret;
+	u8 addr_mode;
+
+	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, ST7586_AUTO_READ_CTRL, 0x9f);
+	mipi_dbi_command(dbi, ST7586_OTP_RW_CTRL, 0x00);
+
+	msleep(10);
+
+	mipi_dbi_command(dbi, ST7586_OTP_READ);
+
+	msleep(20);
+
+	mipi_dbi_command(dbi, ST7586_OTP_CTRL_OUT);
+	mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
+	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);
+
+	msleep(50);
+
+	mipi_dbi_command(dbi, ST7586_SET_VOP_OFFSET, 0x00);
+	mipi_dbi_command(dbi, ST7586_SET_VOP, 0x19, 0x01);
+	mipi_dbi_command(dbi, ST7586_SET_BIAS_SYSTEM, 0x03);
+	mipi_dbi_command(dbi, ST7586_SET_BOOST_LEVEL, 0x07);
+	mipi_dbi_command(dbi, ST7586_ENABLE_ANALOG, 0x1d);
+	mipi_dbi_command(dbi, ST7586_SET_NLINE_INV, 0x00);
+	mipi_dbi_command(dbi, ST7586_DISP_MODE_GRAY);
+	mipi_dbi_command(dbi, ST7586_ENABLE_DDRAM, 0x02);
+
+	switch (dbidev->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(dbi, MIPI_DCS_SET_ADDRESS_MODE, addr_mode);
+
+	mipi_dbi_command(dbi, ST7586_SET_DISP_DUTY, 0x77);
+	mipi_dbi_command(dbi, ST7586_SET_OUTPUT_COM, BRAIN_PAGE_OFFSET);
+	mipi_dbi_command(dbi, ST7586_SET_PART_DISP, 0xa0);
+	mipi_dbi_command(dbi, MIPI_DCS_SET_PARTIAL_AREA, 0x00, 0x00, 0x00, 0x9f);
+	mipi_dbi_command(dbi, MIPI_DCS_EXIT_INVERT_MODE);
+
+	msleep(100);
+
+	dbidev->enabled = true;
+	st7586_fb_dirty(fb, &rect);
+
+	mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
+out_exit:
+	drm_dev_exit(idx);
+}
+
+static void st7586_pipe_disable(struct drm_simple_display_pipe *pipe)
+{
+	struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);
+
+	/*
+	 * This callback is not protected by drm_dev_enter/exit since we want to
+	 * turn off the display on regular driver unload. It's highly unlikely
+	 * that the underlying SPI controller is gone should this be called after
+	 * unplug.
+	 */
+
+	DRM_DEBUG_KMS("\n");
+
+	if (!dbidev->enabled)
+		return;
+
+	mipi_dbi_command(&dbidev->dbi, MIPI_DCS_SET_DISPLAY_OFF);
+	dbidev->enabled = false;
+}
+
+static const u32 st7586_formats[] = {
+	DRM_FORMAT_XRGB8888,
+};
+
+static const struct drm_simple_display_pipe_funcs st7586_pipe_funcs = {
+	.enable		= st7586_pipe_enable,
+	.disable	= st7586_pipe_disable,
+	.update		= st7586_pipe_update,
+	.prepare_fb	= drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+static const struct drm_display_mode st7586_mode = {
+	DRM_SIMPLE_MODE(240, 120, 51, 26),
+};
+
+DEFINE_DRM_GEM_CMA_FOPS(st7586_fops);
+
+static struct drm_driver st7586_driver = {
+	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+	.fops			= &st7586_fops,
+	.release		= mipi_dbi_release,
+	DRM_GEM_CMA_VMAP_DRIVER_OPS,
+	.debugfs_init		= mipi_dbi_debugfs_init,
+	.name			= "brain-st7586",
+	.desc			= "Sitronix ST7586 for Sharp Brain 2nd generation SubLCD",
+	.date			= "20211002",
+	.major			= 1,
+	.minor			= 0,
+};
+
+static const struct of_device_id st7586_of_match[] = {
+	{ .compatible = "brain,st7586" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, st7586_of_match);
+
+static const struct spi_device_id st7586_id[] = {
+	{ "brain-slcd", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, st7586_id);
+
+static int st7586_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct mipi_dbi_dev *dbidev;
+	struct drm_device *drm;
+	struct mipi_dbi *dbi;
+	u32 rotation = 0;
+	size_t bufsize;
+	int ret;
+
+	dbidev = kzalloc(sizeof(*dbidev), GFP_KERNEL);
+	if (!dbidev)
+		return -ENOMEM;
+
+	dbi = &dbidev->dbi;
+	drm = &dbidev->drm;
+	ret = devm_drm_dev_init(dev, drm, &st7586_driver);
+	if (ret) {
+		kfree(dbidev);
+		return ret;
+	}
+
+	drm_mode_config_init(drm);
+
+	bufsize = (st7586_mode.vdisplay + 2) / 3 * st7586_mode.hdisplay;
+
+	dbi->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(dbi->reset)) {
+		DRM_DEV_ERROR(dev, "Failed to get gpio 'reset'\n");
+		return PTR_ERR(dbi->reset);
+	}
+
+	device_property_read_u32(dev, "rotation", &rotation);
+
+	ret = mipi_dbi_spi_init(spi, dbi, NULL);
+	if (ret)
+		return ret;
+
+	/* Cannot read from this controller via SPI */
+	dbi->read_commands = NULL;
+
+	ret = mipi_dbi_dev_init_with_formats(dbidev, &st7586_pipe_funcs,
+					     st7586_formats, ARRAY_SIZE(st7586_formats),
+					     &st7586_mode, rotation, bufsize);
+	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 st7586_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 st7586_shutdown(struct spi_device *spi)
+{
+	drm_atomic_helper_shutdown(spi_get_drvdata(spi));
+}
+
+static struct spi_driver st7586_spi_driver = {
+	.driver = {
+		.name = "brain-st7586",
+		.owner = THIS_MODULE,
+		.of_match_table = st7586_of_match,
+	},
+	.id_table = st7586_id,
+	.probe = st7586_probe,
+	.remove = st7586_remove,
+	.shutdown = st7586_shutdown,
+};
+module_spi_driver(st7586_spi_driver);
+
+MODULE_DESCRIPTION("Sitronix ST7586 DRM driver for Sharp Brain 2nd generation SubLCD");
+MODULE_AUTHOR("Suguru Saito <sg.sgch07@gmail.com>");
+MODULE_LICENSE("GPL");