[RFC 4/5] drm/tinydrm: Add mipi-dbi support

["Noralf Trønnes" <noralf@tronnes.org>]

Add support for MIPI DBI interfaced controllers.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/tinydrm/Kconfig    |   3 +
 drivers/gpu/drm/tinydrm/Makefile   |   3 +
 drivers/gpu/drm/tinydrm/mipi-dbi.c | 231 +++++++++++++++++++++++++++++++++++++
 include/drm/tinydrm/mipi-dbi.h     |  24 ++++
 4 files changed, 261 insertions(+)
 create mode 100644 drivers/gpu/drm/tinydrm/mipi-dbi.c
 create mode 100644 include/drm/tinydrm/mipi-dbi.h

diff --git a/drivers/gpu/drm/tinydrm/Kconfig b/drivers/gpu/drm/tinydrm/Kconfig
index 671239f..a7929e0 100644
--- a/drivers/gpu/drm/tinydrm/Kconfig
+++ b/drivers/gpu/drm/tinydrm/Kconfig
@@ -10,4 +10,7 @@ menuconfig DRM_TINYDRM
 	  Choose this option if you have a tinydrm supported display.
 	  If M is selected the module will be called tinydrm.
 
+config TINYDRM_MIPI_DBI
+	tristate
+
 source "drivers/gpu/drm/tinydrm/lcdreg/Kconfig"
diff --git a/drivers/gpu/drm/tinydrm/Makefile b/drivers/gpu/drm/tinydrm/Makefile
index f4a92d9..35ba822 100644
--- a/drivers/gpu/drm/tinydrm/Makefile
+++ b/drivers/gpu/drm/tinydrm/Makefile
@@ -1,2 +1,5 @@
 obj-$(CONFIG_DRM_TINYDRM)		+= core/
 obj-$(CONFIG_LCDREG)			+= lcdreg/
+
+# Controllers
+obj-$(CONFIG_TINYDRM_MIPI_DBI)		+= mipi-dbi.o
diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
new file mode 100644
index 0000000..3021349
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -0,0 +1,231 @@
+//#define DEBUG
+/*
+ * MIPI Display Bus Interface (DBI) LCD controller support
+ *
+ * Copyright 2016 Noralf Trønnes
+ *
+ * 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 <drm/drm_gem_cma_helper.h>
+#include <drm/tinydrm/lcdreg.h>
+#include <drm/tinydrm/tinydrm.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/swab.h>
+#include <video/mipi_display.h>
+
+#define DCS_POWER_MODE_DISPLAY			BIT(2)
+#define DCS_POWER_MODE_DISPLAY_NORMAL_MODE	BIT(3)
+#define DCS_POWER_MODE_SLEEP_MODE		BIT(4)
+#define DCS_POWER_MODE_PARTIAL_MODE		BIT(5)
+#define DCS_POWER_MODE_IDLE_MODE		BIT(6)
+#define DCS_POWER_MODE_RESERVED_MASK		(BIT(0) | BIT(1) | BIT(7))
+
+/* TODO: Move common functions to a separate module */
+void tinydrm_xrgb8888_to_rgb565(u32 *src, u16 *dst, unsigned num_pixels, bool swap_bytes)
+{
+	int i;
+
+	for (i = 0; i < num_pixels; i++) {
+		*dst = ((*src & 0x00F80000) >> 8) |
+		       ((*src & 0x0000FC00) >> 5) |
+		       ((*src & 0x000000F8) >> 3);
+		if (swap_bytes)
+			*dst = swab16(*dst);
+		src++;
+		dst++;
+	}
+}
+
+// TODO: Pass in regnr
+int tinydrm_update_rgb565_lcdreg(struct tinydrm_device *tdev, struct drm_framebuffer *fb, void *vmem, struct drm_clip_rect *clip)
+{
+	unsigned num_pixels = (clip->x2 - clip->x1 + 1) *
+			      (clip->y2 - clip->y1 + 1);
+	struct lcdreg_transfer tr = {
+		.index = 1,
+		.width = 16,
+		.count = num_pixels
+	};
+	bool byte_swap = false;
+	u16 *buf = NULL;
+	int ret;
+
+	dev_err_once(tdev->base->dev, "pixel_format = %s, bpw = 0x%08x\n", drm_get_format_name(fb->pixel_format), tdev->lcdreg->bits_per_word_mask);
+
+	switch (fb->pixel_format) {
+	case DRM_FORMAT_RGB565:
+		tr.buf = vmem;
+		break;
+	case DRM_FORMAT_XRGB8888:
+		buf = kmalloc(num_pixels * sizeof(u16), GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+
+#if defined(__LITTLE_ENDIAN)
+		byte_swap = !lcdreg_bpw_supported(tdev->lcdreg, 16);
+#endif
+		tinydrm_xrgb8888_to_rgb565(vmem, buf, num_pixels, byte_swap);
+		tr.buf = buf;
+		if (byte_swap) {
+			tr.width = 8;
+			tr.count *= 2;
+		}
+		break;
+	default:
+		dev_err_once(tdev->base->dev,
+			     "pixel_format '%s' is not supported\n",
+			     drm_get_format_name(fb->pixel_format));
+		return -EINVAL;
+	}
+
+	ret = lcdreg_write(tdev->lcdreg, MIPI_DCS_WRITE_MEMORY_START, &tr);
+	kfree(buf);
+
+	return ret;
+}
+
+static void mipi_dbi_deferred_update(struct work_struct *work)
+{
+	struct tinydrm_device *tdev = work_to_tinydrm(work);
+	struct lcdreg *reg = tdev->lcdreg;
+	struct tinydrm_fb_clip fb_clip;
+	struct drm_clip_rect *clip = &fb_clip.clip;
+	int ret;
+
+	dev_dbg(tdev->base->dev, "%s\n", __func__);
+
+	if (!tinydrm_deferred_begin(tdev, &fb_clip))
+		return;
+
+	dev_dbg(tdev->base->dev, "%s: vmem=%p, x1=%u, x2=%u, y1=%u, y2=%u\n", __func__, fb_clip.vmem, clip->x1, clip->x2, clip->y1, clip->y2);
+
+	lcdreg_writereg(reg, MIPI_DCS_SET_COLUMN_ADDRESS,
+			(clip->x1 >> 8) & 0xFF, clip->x1 & 0xFF,
+			(clip->x2 >> 8) & 0xFF, clip->x2 & 0xFF);
+	lcdreg_writereg(reg, MIPI_DCS_SET_PAGE_ADDRESS,
+			(clip->y1 >> 8) & 0xFF, clip->y1 & 0xFF,
+			(clip->y2 >> 8) & 0xFF, clip->y2 & 0xFF);
+
+	ret = tinydrm_update_rgb565_lcdreg(tdev, fb_clip.fb, fb_clip.vmem, clip);
+	if (ret)
+		dev_err_once(tdev->base->dev, "Failed to update display %d\n", ret);
+
+	tinydrm_deferred_end(tdev);
+}
+
+int mipi_dbi_init(struct device *dev, struct tinydrm_device *tdev)
+{
+	tdev->deferred = devm_kzalloc(dev, sizeof(*tdev->deferred),
+				      GFP_KERNEL);
+	if (!tdev->deferred)
+		return -ENOMEM;
+
+	INIT_DELAYED_WORK(&tdev->deferred->dwork, mipi_dbi_deferred_update);
+	tinydrm_reset_clip(&tdev->deferred->fb_clip.clip);
+	tdev->lcdreg->def_width = 8;
+	tdev->dirtyfb = tinydrm_dirtyfb;
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dbi_init);
+
+/* Returns true if the display can be verified to be on */
+bool mipi_dbi_display_is_on(struct lcdreg *reg)
+{
+	u32 val;
+
+	if (!lcdreg_is_readable(reg))
+		return false;
+
+	if (lcdreg_readreg_buf32(reg, MIPI_DCS_GET_POWER_MODE, &val, 1))
+		return false;
+
+	val &= ~DCS_POWER_MODE_RESERVED_MASK;
+
+	if (val != (DCS_POWER_MODE_DISPLAY |
+	    DCS_POWER_MODE_DISPLAY_NORMAL_MODE | DCS_POWER_MODE_SLEEP_MODE))
+		return false;
+
+	DRM_DEBUG_DRIVER("Display is ON\n");
+
+	return true;
+}
+EXPORT_SYMBOL(mipi_dbi_display_is_on);
+
+void mipi_dbi_debug_dump_regs(struct lcdreg *reg)
+{
+	u32 val[4];
+	int ret;
+
+	if (!(lcdreg_is_readable(reg) && (drm_debug & DRM_UT_DRIVER)))
+		return;
+
+	ret = lcdreg_readreg_buf32(reg, MIPI_DCS_GET_DISPLAY_ID, val, 3);
+	if (ret) {
+		dev_warn(reg->dev,
+			 "failed to read from controller: %d", ret);
+		return;
+	}
+
+	/* RDDID is not part of the MIPI standard, but seems to be common */
+	DRM_DEBUG_DRIVER("Display ID (%02x): %02x %02x %02x\n",
+			 MIPI_DCS_GET_DISPLAY_ID, val[0], val[1], val[2]);
+
+	lcdreg_readreg_buf32(reg, MIPI_DCS_GET_DISPLAY_STATUS, val, 4);
+	DRM_DEBUG_DRIVER("Display status (%02x): %02x %02x %02x %02x\n",
+			 MIPI_DCS_GET_DISPLAY_STATUS, val[0], val[1], val[2], val[3]);
+
+	lcdreg_readreg_buf32(reg, MIPI_DCS_GET_POWER_MODE, val, 1);
+	DRM_DEBUG_DRIVER("Power mode (%02x): %02x\n",
+			 MIPI_DCS_GET_POWER_MODE, val[0]);
+
+	lcdreg_readreg_buf32(reg, MIPI_DCS_GET_ADDRESS_MODE, val, 1);
+	DRM_DEBUG_DRIVER("Address mode (%02x): %02x\n",
+			 MIPI_DCS_GET_ADDRESS_MODE, val[0]);
+
+	lcdreg_readreg_buf32(reg, MIPI_DCS_GET_PIXEL_FORMAT, val, 1);
+	DRM_DEBUG_DRIVER("Pixel format (%02x): %02x\n",
+			 MIPI_DCS_GET_PIXEL_FORMAT, val[0]);
+
+	lcdreg_readreg_buf32(reg, MIPI_DCS_GET_DISPLAY_MODE, val, 1);
+	DRM_DEBUG_DRIVER("Display mode (%02x): %02x\n",
+			 MIPI_DCS_GET_DISPLAY_MODE, val[0]);
+
+	lcdreg_readreg_buf32(reg, MIPI_DCS_GET_SIGNAL_MODE, val, 1);
+	DRM_DEBUG_DRIVER("Display signal mode (%02x): %02x\n",
+			 MIPI_DCS_GET_SIGNAL_MODE, val[0]);
+
+	lcdreg_readreg_buf32(reg, MIPI_DCS_GET_DIAGNOSTIC_RESULT, val, 1);
+	DRM_DEBUG_DRIVER("Diagnostic result (%02x): %02x\n",
+			 MIPI_DCS_GET_DIAGNOSTIC_RESULT, val[0]);
+}
+EXPORT_SYMBOL(mipi_dbi_debug_dump_regs);
+
+int mipi_dbi_panel_unprepare(struct drm_panel *panel)
+{
+	struct tinydrm_device *tdev = tinydrm_from_panel(panel);
+	struct lcdreg *reg = tdev->lcdreg;
+
+	/*
+	 * Only do this if we have turned off backlight because if it's on the
+	 * display will in most cases turn all white when the pixels are
+	 * turned off.
+	 */
+	if (tdev->backlight) {
+		lcdreg_writereg(reg, MIPI_DCS_SET_DISPLAY_OFF);
+		lcdreg_writereg(reg, MIPI_DCS_ENTER_SLEEP_MODE);
+	}
+
+	if (tdev->regulator)
+		regulator_disable(tdev->regulator);
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dbi_panel_unprepare);
+
+MODULE_LICENSE("GPL");
diff --git a/include/drm/tinydrm/mipi-dbi.h b/include/drm/tinydrm/mipi-dbi.h
new file mode 100644
index 0000000..108a73b
--- /dev/null
+++ b/include/drm/tinydrm/mipi-dbi.h
@@ -0,0 +1,24 @@
+/*
+ * MIPI Display Bus Interface (DBI) LCD controller support
+ *
+ * Copyright 2016 Noralf Trønnes
+ *
+ * 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.
+ */
+
+#ifndef __LINUX_MIPI_DBI_H
+#define __LINUX_MIPI_DBI_H
+
+struct tinydrm_device;
+struct drm_panel;
+struct lcdreg;
+
+int mipi_dbi_init(struct device *dev, struct tinydrm_device *tdev);
+bool mipi_dbi_display_is_on(struct lcdreg *reg);
+void mipi_dbi_debug_dump_regs(struct lcdreg *reg);
+int mipi_dbi_panel_unprepare(struct drm_panel *panel);
+
+#endif /* __LINUX_MIPI_DBI_H */
-- 
2.2.2

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