diff mbox series

[23/60] drm/panel: Add driver for the Toppology TD028TTEC1 panel

Message ID 20190707181937.6250-20-laurent.pinchart@ideasonboard.com (mailing list archive)
State New, archived
Headers show
Series drm/omap: Replace custom display drivers with drm_bridge and drm_panel | expand

Commit Message

Laurent Pinchart July 7, 2019, 6:19 p.m. UTC
This panel is used on the OpenMoko Neo FreeRunner and Neo 1973.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/gpu/drm/panel/Kconfig                |   8 +
 drivers/gpu/drm/panel/Makefile               |   1 +
 drivers/gpu/drm/panel/panel-tpo-td028ttec1.c | 382 +++++++++++++++++++
 3 files changed, 391 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-tpo-td028ttec1.c

Comments

Sam Ravnborg July 10, 2019, 7:48 a.m. UTC | #1
Hi Laurent.

This driver looks very good.

On Sun, Jul 07, 2019 at 09:19:00PM +0300, Laurent Pinchart wrote:
> This panel is used on the OpenMoko Neo FreeRunner and Neo 1973.
Add info in Kconfig help entry?

> 
> +config DRM_PANEL_TPO_TD028TTEC1
> +	tristate "TPO TD028TTEC1 panel driver"
Maybe spell out TPO like "TPO (Topology) TD028..."

> +	depends on OF && SPI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	help
> +	  Say Y here if you want to enable support for TPO TD028TTEC1 480x640
> +	  2.8" panel.
> +
>  config DRM_PANEL_TPO_TPG110
>  	tristate "TPO TPG 800x400 panel"
>  	depends on OF && SPI && GPIOLIB
>  obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o
> diff --git a/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c b/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
> new file mode 100644
> index 000000000000..05af9ea6339c
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
> +
> +static int jbt_ret_write_0(struct td028ttec1_device *lcd, u8 reg, int *err)
> +{
> +	struct spi_device *spi = lcd->spi;
> +	u16 tx_buf = JBT_COMMAND | reg;
> +	int ret;
> +
> +	if (err && *err)
> +		return *err;
> +
> +	ret = spi_write(spi, (u8 *)&tx_buf, sizeof(tx_buf));
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "%s: SPI write failed: %d\n", __func__, ret);
> +		if (err)
> +			*err = ret;
> +	}
> +
> +	return ret;
> +}
I like the way *err is used here.
So if one call fails, the remaining calls are ignored.

The way the code is written above it will only work on a little endian
box, as the values are stored in an u16 that is later seen as an array of
bytes.
This is also true for the remaing similar functions and may be OK.
We do not see any real demands for big endian anyway.

> +static int td028ttec1_enable(struct drm_panel *panel)
> +{
> +	struct td028ttec1_device *lcd = to_td028ttec1_device(panel);
> +	unsigned int i;
> +	int ret = 0;
> +
> +	/* Three times command zero */
> +	for (i = 0; i < 3; ++i) {
> +		jbt_ret_write_0(lcd, 0x00, &ret);
> +		usleep_range(1000, 2000);
> +	}
> +
> +	if (ret)
> +		return ret;
This if (ret) is really not needed.
It somehow short-circuit the principle used in the rest of the function
here. All jbt_reg_write() will be nop if ret != 0.

> +
> +	/* deep standby out */
> +	jbt_reg_write_1(lcd, JBT_REG_POWER_ON_OFF, 0x17, &ret);
> +
> +	/* RGB I/F on, RAM write off, QVGA through, SIGCON enable */
> +	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE, 0x80, &ret);
> +
> +	/* Quad mode off */
> +	jbt_reg_write_1(lcd, JBT_REG_QUAD_RATE, 0x00, &ret);
> +
> +	/* AVDD on, XVDD on */
> +	jbt_reg_write_1(lcd, JBT_REG_POWER_ON_OFF, 0x16, &ret);
> +
> +	/* Output control */
> +	jbt_reg_write_2(lcd, JBT_REG_OUTPUT_CONTROL, 0xfff9, &ret);
> +
> +	/* Sleep mode off */
> +	jbt_ret_write_0(lcd, JBT_REG_SLEEP_OUT, &ret);
> +
> +	/* at this point we have like 50% grey */
> +
> +	/* initialize register set */
> +	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE1, 0x01, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE2, 0x00, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_RGB_FORMAT, 0x60, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_DRIVE_SYSTEM, 0x10, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_OP, 0x56, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_MODE, 0x33, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_FREQ, 0x11, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_FREQ, 0x11, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_OPAMP_SYSCLK, 0x02, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_VSC_VOLTAGE, 0x2b, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_VCOM_VOLTAGE, 0x40, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_EXT_DISPL, 0x03, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_DCCLK_DCEV, 0x04, &ret);
> +	/*
> +	 * default of 0x02 in JBT_REG_ASW_SLEW responsible for 72Hz requirement
> +	 * to avoid red / blue flicker
> +	 */
> +	jbt_reg_write_1(lcd, JBT_REG_ASW_SLEW, 0x04, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_DUMMY_DISPLAY, 0x00, &ret);
> +
> +	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_A, 0x11, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_B, 0x11, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_C, 0x11, &ret);
> +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_D, 0x2040, &ret);
> +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_E, 0x60c0, &ret);
> +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_F, 0x1020, &ret);
> +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_G, 0x60c0, &ret);
> +
> +	jbt_reg_write_2(lcd, JBT_REG_GAMMA1_FINE_1, 0x5533, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_FINE_2, 0x00, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_INCLINATION, 0x00, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_BLUE_OFFSET, 0x00, &ret);
> +
> +	jbt_reg_write_2(lcd, JBT_REG_HCLOCK_VGA, 0x1f0, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_BLANK_CONTROL, 0x02, &ret);
> +	jbt_reg_write_2(lcd, JBT_REG_BLANK_TH_TV, 0x0804, &ret);
> +
> +	jbt_reg_write_1(lcd, JBT_REG_CKV_ON_OFF, 0x01, &ret);
> +	jbt_reg_write_2(lcd, JBT_REG_CKV_1_2, 0x0000, &ret);
> +
> +	jbt_reg_write_2(lcd, JBT_REG_OEV_TIMING, 0x0d0e, &ret);
> +	jbt_reg_write_2(lcd, JBT_REG_ASW_TIMING_1, 0x11a4, &ret);
> +	jbt_reg_write_1(lcd, JBT_REG_ASW_TIMING_2, 0x0e, &ret);
> +
> +	jbt_ret_write_0(lcd, JBT_REG_DISPLAY_ON, &ret);
> +
> +	if (ret)
> +		return ret;
> +
> +	backlight_enable(lcd->backlight);
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode td028ttec1_mode = {
> +	.clock = 22153,
> +	.hdisplay = 480,
> +	.hsync_start = 480 + 24,
> +	.hsync_end = 480 + 24 + 8,
> +	.htotal = 480 + 24 + 8 + 8,
> +	.vdisplay = 640,
> +	.vsync_start = 640 + 4,
> +	.vsync_end = 640 + 4 + 2,
> +	.vtotal = 640 + 4 + 2 + 2,
> +	.vrefresh = 66,
> +	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
> +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> +};
Add width_mm + height_mm.

> +static int td028ttec1_remove(struct spi_device *spi)
> +{
> +	struct td028ttec1_device *lcd = spi_get_drvdata(spi);
> +
> +	drm_panel_remove(&lcd->panel);
> +	td028ttec1_disable(&lcd->panel);
Use drm_panel_disable();

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id td028ttec1_of_match[] = {
> +	{ .compatible = "tpo,td028ttec1", },
> +	/* DT backward compatibility. */
> +	{ .compatible = "toppoly,td028ttec1", },
> +	{},
{ /* sentinel */ },

With the above nits fixed/considered:
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>

	Sam
Laurent Pinchart Aug. 8, 2019, 3:43 p.m. UTC | #2
Hi Sam,

On Wed, Jul 10, 2019 at 09:48:55AM +0200, Sam Ravnborg wrote:
> Hi Laurent.
> 
> This driver looks very good.
> 
> On Sun, Jul 07, 2019 at 09:19:00PM +0300, Laurent Pinchart wrote:
> > This panel is used on the OpenMoko Neo FreeRunner and Neo 1973.
> 
> Add info in Kconfig help entry?
> 
> > +config DRM_PANEL_TPO_TD028TTEC1
> > +	tristate "TPO TD028TTEC1 panel driver"
> 
> Maybe spell out TPO like "TPO (Topology) TD028..."
>
> > +	depends on OF && SPI
> > +	depends on BACKLIGHT_CLASS_DEVICE
> > +	help
> > +	  Say Y here if you want to enable support for TPO TD028TTEC1 480x640
> > +	  2.8" panel.
> > +
> >  config DRM_PANEL_TPO_TPG110
> >  	tristate "TPO TPG 800x400 panel"
> >  	depends on OF && SPI && GPIOLIB
> >  obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o
> > diff --git a/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c b/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
> > new file mode 100644
> > index 000000000000..05af9ea6339c
> > --- /dev/null
> > +++ b/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
> > +
> > +static int jbt_ret_write_0(struct td028ttec1_device *lcd, u8 reg, int *err)
> > +{
> > +	struct spi_device *spi = lcd->spi;
> > +	u16 tx_buf = JBT_COMMAND | reg;
> > +	int ret;
> > +
> > +	if (err && *err)
> > +		return *err;
> > +
> > +	ret = spi_write(spi, (u8 *)&tx_buf, sizeof(tx_buf));
> > +	if (ret < 0) {
> > +		dev_err(&spi->dev, "%s: SPI write failed: %d\n", __func__, ret);
> > +		if (err)
> > +			*err = ret;
> > +	}
> > +
> > +	return ret;
> > +}
> 
> I like the way *err is used here.
> So if one call fails, the remaining calls are ignored.

I think it's a construct that could be used in more drivers, when
dealing with large sequences of writes.

> The way the code is written above it will only work on a little endian
> box, as the values are stored in an u16 that is later seen as an array of
> bytes.
> This is also true for the remaing similar functions and may be OK.
> We do not see any real demands for big endian anyway.

This could be fixed if desired, but I would do so on top of this patch
to minimise the changes compared to the omapdrm-specific panel driver.

> > +static int td028ttec1_enable(struct drm_panel *panel)
> > +{
> > +	struct td028ttec1_device *lcd = to_td028ttec1_device(panel);
> > +	unsigned int i;
> > +	int ret = 0;
> > +
> > +	/* Three times command zero */
> > +	for (i = 0; i < 3; ++i) {
> > +		jbt_ret_write_0(lcd, 0x00, &ret);
> > +		usleep_range(1000, 2000);
> > +	}
> > +
> > +	if (ret)
> > +		return ret;
> 
> This if (ret) is really not needed.
> It somehow short-circuit the principle used in the rest of the function
> here. All jbt_reg_write() will be nop if ret != 0.

I'll drop it.

> > +
> > +	/* deep standby out */
> > +	jbt_reg_write_1(lcd, JBT_REG_POWER_ON_OFF, 0x17, &ret);
> > +
> > +	/* RGB I/F on, RAM write off, QVGA through, SIGCON enable */
> > +	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE, 0x80, &ret);
> > +
> > +	/* Quad mode off */
> > +	jbt_reg_write_1(lcd, JBT_REG_QUAD_RATE, 0x00, &ret);
> > +
> > +	/* AVDD on, XVDD on */
> > +	jbt_reg_write_1(lcd, JBT_REG_POWER_ON_OFF, 0x16, &ret);
> > +
> > +	/* Output control */
> > +	jbt_reg_write_2(lcd, JBT_REG_OUTPUT_CONTROL, 0xfff9, &ret);
> > +
> > +	/* Sleep mode off */
> > +	jbt_ret_write_0(lcd, JBT_REG_SLEEP_OUT, &ret);
> > +
> > +	/* at this point we have like 50% grey */
> > +
> > +	/* initialize register set */
> > +	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE1, 0x01, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE2, 0x00, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_RGB_FORMAT, 0x60, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_DRIVE_SYSTEM, 0x10, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_OP, 0x56, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_MODE, 0x33, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_FREQ, 0x11, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_FREQ, 0x11, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_OPAMP_SYSCLK, 0x02, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_VSC_VOLTAGE, 0x2b, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_VCOM_VOLTAGE, 0x40, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_EXT_DISPL, 0x03, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_DCCLK_DCEV, 0x04, &ret);
> > +	/*
> > +	 * default of 0x02 in JBT_REG_ASW_SLEW responsible for 72Hz requirement
> > +	 * to avoid red / blue flicker
> > +	 */
> > +	jbt_reg_write_1(lcd, JBT_REG_ASW_SLEW, 0x04, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_DUMMY_DISPLAY, 0x00, &ret);
> > +
> > +	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_A, 0x11, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_B, 0x11, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_C, 0x11, &ret);
> > +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_D, 0x2040, &ret);
> > +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_E, 0x60c0, &ret);
> > +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_F, 0x1020, &ret);
> > +	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_G, 0x60c0, &ret);
> > +
> > +	jbt_reg_write_2(lcd, JBT_REG_GAMMA1_FINE_1, 0x5533, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_FINE_2, 0x00, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_INCLINATION, 0x00, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_BLUE_OFFSET, 0x00, &ret);
> > +
> > +	jbt_reg_write_2(lcd, JBT_REG_HCLOCK_VGA, 0x1f0, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_BLANK_CONTROL, 0x02, &ret);
> > +	jbt_reg_write_2(lcd, JBT_REG_BLANK_TH_TV, 0x0804, &ret);
> > +
> > +	jbt_reg_write_1(lcd, JBT_REG_CKV_ON_OFF, 0x01, &ret);
> > +	jbt_reg_write_2(lcd, JBT_REG_CKV_1_2, 0x0000, &ret);
> > +
> > +	jbt_reg_write_2(lcd, JBT_REG_OEV_TIMING, 0x0d0e, &ret);
> > +	jbt_reg_write_2(lcd, JBT_REG_ASW_TIMING_1, 0x11a4, &ret);
> > +	jbt_reg_write_1(lcd, JBT_REG_ASW_TIMING_2, 0x0e, &ret);
> > +
> > +	jbt_ret_write_0(lcd, JBT_REG_DISPLAY_ON, &ret);
> > +
> > +	if (ret)
> > +		return ret;
> > +
> > +	backlight_enable(lcd->backlight);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct drm_display_mode td028ttec1_mode = {
> > +	.clock = 22153,
> > +	.hdisplay = 480,
> > +	.hsync_start = 480 + 24,
> > +	.hsync_end = 480 + 24 + 8,
> > +	.htotal = 480 + 24 + 8 + 8,
> > +	.vdisplay = 640,
> > +	.vsync_start = 640 + 4,
> > +	.vsync_end = 640 + 4 + 2,
> > +	.vtotal = 640 + 4 + 2 + 2,
> > +	.vrefresh = 66,
> > +	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
> > +	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
> > +};
> 
> Add width_mm + height_mm.
> 
> > +static int td028ttec1_remove(struct spi_device *spi)
> > +{
> > +	struct td028ttec1_device *lcd = spi_get_drvdata(spi);
> > +
> > +	drm_panel_remove(&lcd->panel);
> > +	td028ttec1_disable(&lcd->panel);
> 
> Use drm_panel_disable();
> 
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id td028ttec1_of_match[] = {
> > +	{ .compatible = "tpo,td028ttec1", },
> > +	/* DT backward compatibility. */
> > +	{ .compatible = "toppoly,td028ttec1", },
> > +	{},
> 
> { /* sentinel */ },
> 
> With the above nits fixed/considered:
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> 
> 	Sam
diff mbox series

Patch

diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index dc10f727689a..b7099d211061 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -304,6 +304,14 @@  config DRM_PANEL_SONY_ACX565AKM
 	  Say Y here if you want to enable support for the Sony ACX565AKM
 	  800x600 3.5" panel.
 
+config DRM_PANEL_TPO_TD028TTEC1
+	tristate "TPO TD028TTEC1 panel driver"
+	depends on OF && SPI
+	depends on BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y here if you want to enable support for TPO TD028TTEC1 480x640
+	  2.8" panel.
+
 config DRM_PANEL_TPO_TPG110
 	tristate "TPO TPG 800x400 panel"
 	depends on OF && SPI && GPIOLIB
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index 84cbc069f6cd..a1d4de64c0b1 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -32,5 +32,6 @@  obj-$(CONFIG_DRM_PANEL_SHARP_LS043T1LE01) += panel-sharp-ls043t1le01.o
 obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7701) += panel-sitronix-st7701.o
 obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
 obj-$(CONFIG_DRM_PANEL_SONY_ACX565AKM) += panel-sony-acx565akm.o
+obj-$(CONFIG_DRM_PANEL_TPO_TD028TTEC1) += panel-tpo-td028ttec1.o
 obj-$(CONFIG_DRM_PANEL_TPO_TPG110) += panel-tpo-tpg110.o
 obj-$(CONFIG_DRM_PANEL_TRULY_NT35597_WQXGA) += panel-truly-nt35597.o
diff --git a/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c b/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
new file mode 100644
index 000000000000..05af9ea6339c
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-tpo-td028ttec1.c
@@ -0,0 +1,382 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Toppoly TD028TTEC1 Panel Driver
+ *
+ * Copyright (C) 2019 Texas Instruments Incorporated
+ *
+ * Based on the omapdrm-specific panel-tpo-td028ttec1 driver
+ *
+ * Copyright (C) 2008 Nokia Corporation
+ * Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
+ *
+ * Neo 1973 code (jbt6k74.c):
+ * Copyright (C) 2006-2007 OpenMoko, Inc.
+ * Author: Harald Welte <laforge@openmoko.org>
+ *
+ * Ported and adapted from Neo 1973 U-Boot by:
+ * H. Nikolaus Schaller <hns@goldelico.com>
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#include <drm/drm_connector.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+
+#define JBT_COMMAND			0x000
+#define JBT_DATA			0x100
+
+#define JBT_REG_SLEEP_IN		0x10
+#define JBT_REG_SLEEP_OUT		0x11
+
+#define JBT_REG_DISPLAY_OFF		0x28
+#define JBT_REG_DISPLAY_ON		0x29
+
+#define JBT_REG_RGB_FORMAT		0x3a
+#define JBT_REG_QUAD_RATE		0x3b
+
+#define JBT_REG_POWER_ON_OFF		0xb0
+#define JBT_REG_BOOSTER_OP		0xb1
+#define JBT_REG_BOOSTER_MODE		0xb2
+#define JBT_REG_BOOSTER_FREQ		0xb3
+#define JBT_REG_OPAMP_SYSCLK		0xb4
+#define JBT_REG_VSC_VOLTAGE		0xb5
+#define JBT_REG_VCOM_VOLTAGE		0xb6
+#define JBT_REG_EXT_DISPL		0xb7
+#define JBT_REG_OUTPUT_CONTROL		0xb8
+#define JBT_REG_DCCLK_DCEV		0xb9
+#define JBT_REG_DISPLAY_MODE1		0xba
+#define JBT_REG_DISPLAY_MODE2		0xbb
+#define JBT_REG_DISPLAY_MODE		0xbc
+#define JBT_REG_ASW_SLEW		0xbd
+#define JBT_REG_DUMMY_DISPLAY		0xbe
+#define JBT_REG_DRIVE_SYSTEM		0xbf
+
+#define JBT_REG_SLEEP_OUT_FR_A		0xc0
+#define JBT_REG_SLEEP_OUT_FR_B		0xc1
+#define JBT_REG_SLEEP_OUT_FR_C		0xc2
+#define JBT_REG_SLEEP_IN_LCCNT_D	0xc3
+#define JBT_REG_SLEEP_IN_LCCNT_E	0xc4
+#define JBT_REG_SLEEP_IN_LCCNT_F	0xc5
+#define JBT_REG_SLEEP_IN_LCCNT_G	0xc6
+
+#define JBT_REG_GAMMA1_FINE_1		0xc7
+#define JBT_REG_GAMMA1_FINE_2		0xc8
+#define JBT_REG_GAMMA1_INCLINATION	0xc9
+#define JBT_REG_GAMMA1_BLUE_OFFSET	0xca
+
+#define JBT_REG_BLANK_CONTROL		0xcf
+#define JBT_REG_BLANK_TH_TV		0xd0
+#define JBT_REG_CKV_ON_OFF		0xd1
+#define JBT_REG_CKV_1_2			0xd2
+#define JBT_REG_OEV_TIMING		0xd3
+#define JBT_REG_ASW_TIMING_1		0xd4
+#define JBT_REG_ASW_TIMING_2		0xd5
+
+#define JBT_REG_HCLOCK_VGA		0xec
+#define JBT_REG_HCLOCK_QVGA		0xed
+
+struct td028ttec1_device {
+	struct drm_panel panel;
+
+	struct spi_device *spi;
+	struct backlight_device *backlight;
+};
+
+#define to_td028ttec1_device(p) container_of(p, struct td028ttec1_device, panel)
+
+static int jbt_ret_write_0(struct td028ttec1_device *lcd, u8 reg, int *err)
+{
+	struct spi_device *spi = lcd->spi;
+	u16 tx_buf = JBT_COMMAND | reg;
+	int ret;
+
+	if (err && *err)
+		return *err;
+
+	ret = spi_write(spi, (u8 *)&tx_buf, sizeof(tx_buf));
+	if (ret < 0) {
+		dev_err(&spi->dev, "%s: SPI write failed: %d\n", __func__, ret);
+		if (err)
+			*err = ret;
+	}
+
+	return ret;
+}
+
+static int jbt_reg_write_1(struct td028ttec1_device *lcd,
+			   u8 reg, u8 data, int *err)
+{
+	struct spi_device *spi = lcd->spi;
+	u16 tx_buf[2];
+	int ret;
+
+	if (err && *err)
+		return *err;
+
+	tx_buf[0] = JBT_COMMAND | reg;
+	tx_buf[1] = JBT_DATA | data;
+
+	ret = spi_write(spi, (u8 *)tx_buf, sizeof(tx_buf));
+	if (ret < 0) {
+		dev_err(&spi->dev, "%s: SPI write failed: %d\n", __func__, ret);
+		if (err)
+			*err = ret;
+	}
+
+	return ret;
+}
+
+static int jbt_reg_write_2(struct td028ttec1_device *lcd,
+			   u8 reg, u16 data, int *err)
+{
+	struct spi_device *spi = lcd->spi;
+	u16 tx_buf[3];
+	int ret;
+
+	if (err && *err)
+		return *err;
+
+	tx_buf[0] = JBT_COMMAND | reg;
+	tx_buf[1] = JBT_DATA | (data >> 8);
+	tx_buf[2] = JBT_DATA | (data & 0xff);
+
+	ret = spi_write(spi, (u8 *)tx_buf, sizeof(tx_buf));
+	if (ret < 0) {
+		dev_err(&spi->dev, "%s: SPI write failed: %d\n", __func__, ret);
+		if (err)
+			*err = ret;
+	}
+
+	return ret;
+}
+
+static int td028ttec1_disable(struct drm_panel *panel)
+{
+	struct td028ttec1_device *lcd = to_td028ttec1_device(panel);
+
+	backlight_disable(lcd->backlight);
+
+	jbt_ret_write_0(lcd, JBT_REG_DISPLAY_OFF, NULL);
+	jbt_reg_write_2(lcd, JBT_REG_OUTPUT_CONTROL, 0x8002, NULL);
+	jbt_ret_write_0(lcd, JBT_REG_SLEEP_IN, NULL);
+	jbt_reg_write_1(lcd, JBT_REG_POWER_ON_OFF, 0x00, NULL);
+
+	return 0;
+}
+
+static int td028ttec1_enable(struct drm_panel *panel)
+{
+	struct td028ttec1_device *lcd = to_td028ttec1_device(panel);
+	unsigned int i;
+	int ret = 0;
+
+	/* Three times command zero */
+	for (i = 0; i < 3; ++i) {
+		jbt_ret_write_0(lcd, 0x00, &ret);
+		usleep_range(1000, 2000);
+	}
+
+	if (ret)
+		return ret;
+
+	/* deep standby out */
+	jbt_reg_write_1(lcd, JBT_REG_POWER_ON_OFF, 0x17, &ret);
+
+	/* RGB I/F on, RAM write off, QVGA through, SIGCON enable */
+	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE, 0x80, &ret);
+
+	/* Quad mode off */
+	jbt_reg_write_1(lcd, JBT_REG_QUAD_RATE, 0x00, &ret);
+
+	/* AVDD on, XVDD on */
+	jbt_reg_write_1(lcd, JBT_REG_POWER_ON_OFF, 0x16, &ret);
+
+	/* Output control */
+	jbt_reg_write_2(lcd, JBT_REG_OUTPUT_CONTROL, 0xfff9, &ret);
+
+	/* Sleep mode off */
+	jbt_ret_write_0(lcd, JBT_REG_SLEEP_OUT, &ret);
+
+	/* at this point we have like 50% grey */
+
+	/* initialize register set */
+	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE1, 0x01, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_DISPLAY_MODE2, 0x00, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_RGB_FORMAT, 0x60, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_DRIVE_SYSTEM, 0x10, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_OP, 0x56, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_MODE, 0x33, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_FREQ, 0x11, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_BOOSTER_FREQ, 0x11, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_OPAMP_SYSCLK, 0x02, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_VSC_VOLTAGE, 0x2b, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_VCOM_VOLTAGE, 0x40, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_EXT_DISPL, 0x03, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_DCCLK_DCEV, 0x04, &ret);
+	/*
+	 * default of 0x02 in JBT_REG_ASW_SLEW responsible for 72Hz requirement
+	 * to avoid red / blue flicker
+	 */
+	jbt_reg_write_1(lcd, JBT_REG_ASW_SLEW, 0x04, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_DUMMY_DISPLAY, 0x00, &ret);
+
+	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_A, 0x11, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_B, 0x11, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_SLEEP_OUT_FR_C, 0x11, &ret);
+	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_D, 0x2040, &ret);
+	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_E, 0x60c0, &ret);
+	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_F, 0x1020, &ret);
+	jbt_reg_write_2(lcd, JBT_REG_SLEEP_IN_LCCNT_G, 0x60c0, &ret);
+
+	jbt_reg_write_2(lcd, JBT_REG_GAMMA1_FINE_1, 0x5533, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_FINE_2, 0x00, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_INCLINATION, 0x00, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_GAMMA1_BLUE_OFFSET, 0x00, &ret);
+
+	jbt_reg_write_2(lcd, JBT_REG_HCLOCK_VGA, 0x1f0, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_BLANK_CONTROL, 0x02, &ret);
+	jbt_reg_write_2(lcd, JBT_REG_BLANK_TH_TV, 0x0804, &ret);
+
+	jbt_reg_write_1(lcd, JBT_REG_CKV_ON_OFF, 0x01, &ret);
+	jbt_reg_write_2(lcd, JBT_REG_CKV_1_2, 0x0000, &ret);
+
+	jbt_reg_write_2(lcd, JBT_REG_OEV_TIMING, 0x0d0e, &ret);
+	jbt_reg_write_2(lcd, JBT_REG_ASW_TIMING_1, 0x11a4, &ret);
+	jbt_reg_write_1(lcd, JBT_REG_ASW_TIMING_2, 0x0e, &ret);
+
+	jbt_ret_write_0(lcd, JBT_REG_DISPLAY_ON, &ret);
+
+	if (ret)
+		return ret;
+
+	backlight_enable(lcd->backlight);
+
+	return 0;
+}
+
+static const struct drm_display_mode td028ttec1_mode = {
+	.clock = 22153,
+	.hdisplay = 480,
+	.hsync_start = 480 + 24,
+	.hsync_end = 480 + 24 + 8,
+	.htotal = 480 + 24 + 8 + 8,
+	.vdisplay = 640,
+	.vsync_start = 640 + 4,
+	.vsync_end = 640 + 4 + 2,
+	.vtotal = 640 + 4 + 2 + 2,
+	.vrefresh = 66,
+	.type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
+	.flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
+};
+
+static int td028ttec1_get_modes(struct drm_panel *panel)
+{
+	struct drm_connector *connector = panel->connector;
+	struct drm_display_mode *mode;
+
+	mode = drm_mode_duplicate(panel->drm, &td028ttec1_mode);
+	if (!mode)
+		return -ENOMEM;
+
+	drm_mode_set_name(mode);
+	drm_mode_probed_add(connector, mode);
+
+	connector->display_info.width_mm = 43;
+	connector->display_info.height_mm = 58;
+	/*
+	 * FIXME: According to the datasheet sync signals are sampled on the
+	 * rising edge of the clock, but the code running on the OpenMoko Neo
+	 * FreeRunner and Neo 1973 indicates sampling on the falling edge. This
+	 * should be tested on a real device.
+	 */
+	connector->display_info.bus_flags = DRM_BUS_FLAG_DE_HIGH
+					  | DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE
+					  | DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE;
+
+	return 1;
+}
+
+static const struct drm_panel_funcs td028ttec1_funcs = {
+	.disable = td028ttec1_disable,
+	.enable = td028ttec1_enable,
+	.get_modes = td028ttec1_get_modes,
+};
+
+static int td028ttec1_probe(struct spi_device *spi)
+{
+	struct td028ttec1_device *lcd;
+	int ret;
+
+	lcd = devm_kzalloc(&spi->dev, sizeof(*lcd), GFP_KERNEL);
+	if (lcd == NULL)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, lcd);
+	lcd->spi = spi;
+
+	lcd->backlight = devm_of_find_backlight(&spi->dev);
+	if (IS_ERR(lcd->backlight))
+		return PTR_ERR(lcd->backlight);
+
+	spi->mode = SPI_MODE_3;
+	spi->bits_per_word = 9;
+
+	ret = spi_setup(spi);
+	if (ret < 0) {
+		dev_err(&spi->dev, "failed to setup SPI: %d\n", ret);
+		return ret;
+	}
+
+	drm_panel_init(&lcd->panel);
+	lcd->panel.dev = &lcd->spi->dev;
+	lcd->panel.funcs = &td028ttec1_funcs;
+
+	return drm_panel_add(&lcd->panel);
+}
+
+static int td028ttec1_remove(struct spi_device *spi)
+{
+	struct td028ttec1_device *lcd = spi_get_drvdata(spi);
+
+	drm_panel_remove(&lcd->panel);
+	td028ttec1_disable(&lcd->panel);
+
+	return 0;
+}
+
+static const struct of_device_id td028ttec1_of_match[] = {
+	{ .compatible = "tpo,td028ttec1", },
+	/* DT backward compatibility. */
+	{ .compatible = "toppoly,td028ttec1", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, td028ttec1_of_match);
+
+static const struct spi_device_id td028ttec1_ids[] = {
+	{ "tpo,td028ttec1", 0},
+	{ "toppoly,td028ttec1", 0 },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(spi, td028ttec1_ids);
+
+static struct spi_driver td028ttec1_driver = {
+	.probe		= td028ttec1_probe,
+	.remove		= td028ttec1_remove,
+	.id_table	= td028ttec1_ids,
+	.driver		= {
+		.name   = "panel-tpo-td028ttec1",
+		.of_match_table = td028ttec1_of_match,
+	},
+};
+
+module_spi_driver(td028ttec1_driver);
+
+MODULE_AUTHOR("H. Nikolaus Schaller <hns@goldelico.com>");
+MODULE_DESCRIPTION("Toppoly TD028TTEC1 panel driver");
+MODULE_LICENSE("GPL");