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Subject[PATCH v4 3/5] drm/tinydrm: add support for LEGO MINDSTORMS EV3 LCD
Date
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>
---

v4 changes:
* correct order for MAINTAINERS entry
* Drop code not used by LEGO EV3 (regulator, backlight, suspend/resume)
* Make gpios required
* Use lookup table for pixel packing algorithm
* Don't modify clip when used as function parameter
* Use roundup/rounddown macros


MAINTAINERS | 6 +
drivers/gpu/drm/tinydrm/Kconfig | 10 +
drivers/gpu/drm/tinydrm/Makefile | 1 +
drivers/gpu/drm/tinydrm/st7586.c | 428 +++++++++++++++++++++++++++++++++++++++
4 files changed, 445 insertions(+)
create mode 100644 drivers/gpu/drm/tinydrm/st7586.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a1e772e..19ca3e6 100644
--- a/MAINTAINERS
+++ b/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/
diff --git a/drivers/gpu/drm/tinydrm/Kconfig b/drivers/gpu/drm/tinydrm/Kconfig
index f17c3ca..2e790e7 100644
--- a/drivers/gpu/drm/tinydrm/Kconfig
+++ b/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.
diff --git a/drivers/gpu/drm/tinydrm/Makefile b/drivers/gpu/drm/tinydrm/Makefile
index 95bb4d4..0c184bd 100644
--- a/drivers/gpu/drm/tinydrm/Makefile
+++ b/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
diff --git a/drivers/gpu/drm/tinydrm/st7586.c b/drivers/gpu/drm/tinydrm/st7586.c
new file mode 100644
index 0000000..1b39d3f
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/st7586.c
@@ -0,0 +1,428 @@
+/*
+ * 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");
--
2.7.4
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