From 899f24ed8d3a6d87734dc4252b4c3511b1128ad4 Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Sun, 23 Feb 2020 13:18:41 +0100
Subject: drm/panel: Add driver for Novatek NT35510-based panels

This adds a driver for panels based on the Novatek NT35510
display driver IC, such as the Hydis HVA40WV1 panel found
in the Samsung GT-S7710.

The NT35510 can be used with both internal and external
backlight (such as GPIO backlight) so we support both:
if no external backlight is found, we register a subdriver
for the internal backlight.

Cc: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200223121841.26836-3-linus.walleij@linaro.org
---
 drivers/gpu/drm/panel/panel-novatek-nt35510.c | 1098 +++++++++++++++++++++++++
 1 file changed, 1098 insertions(+)
 create mode 100644 drivers/gpu/drm/panel/panel-novatek-nt35510.c

(limited to 'drivers/gpu/drm/panel/panel-novatek-nt35510.c')

diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35510.c b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
new file mode 100644
index 000000000000..b4c014126781
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-novatek-nt35510.c
@@ -0,0 +1,1098 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Novatek NT35510 panel driver
+ * Copyright (C) 2020 Linus Walleij <linus.walleij@linaro.org>
+ * Based on code by Robert Teather (C) 2012 Samsung
+ *
+ * This display driver (and I refer to the physical component NT35510,
+ * not this Linux kernel software driver) can handle:
+ * 480x864, 480x854, 480x800, 480x720 and 480x640 pixel displays.
+ * It has 480x840x24bit SRAM embedded for storing a frame.
+ * When powered on the display is by default in 480x800 mode.
+ *
+ * The actual panels using this component have different names, but
+ * the code needed to set up and configure the panel will be similar,
+ * so they should all use the NT35510 driver with appropriate configuration
+ * per-panel, e.g. for physical size.
+ *
+ * This driver is for the DSI interface to panels using the NT35510.
+ *
+ * The NT35510 can also use an RGB (DPI) interface combined with an
+ * I2C or SPI interface for setting up the NT35510. If this is needed
+ * this panel driver should be refactored to also support that use
+ * case.
+ */
+#include <linux/backlight.h>
+#include <linux/bitops.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
+#include <video/mipi_display.h>
+
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_print.h>
+
+#define MCS_CMD_MAUCCTR		0xF0 /* Manufacturer command enable */
+#define MCS_CMD_READ_ID1	0xDA
+#define MCS_CMD_READ_ID2	0xDB
+#define MCS_CMD_READ_ID3	0xDC
+#define MCS_CMD_MTP_READ_SETTING 0xF8 /* Uncertain about name */
+#define MCS_CMD_MTP_READ_PARAM 0xFF /* Uncertain about name */
+
+/*
+ * These manufacturer commands are available after we enable manufacturer
+ * command set (MCS) for page 0.
+ */
+#define NT35510_P0_DOPCTR 0xB1
+#define NT35510_P0_SDHDTCTR 0xB6
+#define NT35510_P0_GSEQCTR 0xB7
+#define NT35510_P0_SDEQCTR 0xB8
+#define NT35510_P0_SDVPCTR 0xBA
+#define NT35510_P0_DPFRCTR1 0xBD
+#define NT35510_P0_DPFRCTR2 0xBE
+#define NT35510_P0_DPFRCTR3 0xBF
+#define NT35510_P0_DPMCTR12 0xCC
+
+#define NT35510_P0_DOPCTR_LEN 2
+#define NT35510_P0_GSEQCTR_LEN 2
+#define NT35510_P0_SDEQCTR_LEN 4
+#define NT35510_P0_SDVPCTR_LEN 1
+#define NT35510_P0_DPFRCTR1_LEN 5
+#define NT35510_P0_DPFRCTR2_LEN 5
+#define NT35510_P0_DPFRCTR3_LEN 5
+#define NT35510_P0_DPMCTR12_LEN 3
+
+#define NT35510_DOPCTR_0_RAMKP BIT(7) /* Contents kept in sleep */
+#define NT35510_DOPCTR_0_DSITE BIT(6) /* Enable TE signal */
+#define NT35510_DOPCTR_0_DSIG BIT(5) /* Enable generic read/write */
+#define NT35510_DOPCTR_0_DSIM BIT(4) /* Enable video mode on DSI */
+#define NT35510_DOPCTR_0_EOTP BIT(3) /* Support EoTP */
+#define NT35510_DOPCTR_0_N565 BIT(2) /* RGB or BGR pixel format */
+#define NT35510_DOPCTR_1_TW_PWR_SEL BIT(4) /* TE power selector */
+#define NT35510_DOPCTR_1_CRGB BIT(3) /* RGB or BGR byte order */
+#define NT35510_DOPCTR_1_CTB BIT(2) /* Vertical scanning direction */
+#define NT35510_DOPCTR_1_CRL BIT(1) /* Source driver data shift */
+#define NT35510_P0_SDVPCTR_PRG BIT(2) /* 0 = normal operation, 1 = VGLO */
+#define NT35510_P0_SDVPCTR_AVDD 0 /* source driver output = AVDD */
+#define NT35510_P0_SDVPCTR_OFFCOL 1 /* source driver output = off color */
+#define NT35510_P0_SDVPCTR_AVSS 2 /* source driver output = AVSS */
+#define NT35510_P0_SDVPCTR_HI_Z 3 /* source driver output = High impedance */
+
+/*
+ * These manufacturer commands are available after we enable manufacturer
+ * command set (MCS) for page 1.
+ */
+#define NT35510_P1_SETAVDD 0xB0
+#define NT35510_P1_SETAVEE 0xB1
+#define NT35510_P1_SETVCL 0xB2
+#define NT35510_P1_SETVGH 0xB3
+#define NT35510_P1_SETVRGH 0xB4
+#define NT35510_P1_SETVGL 0xB5
+#define NT35510_P1_BT1CTR 0xB6
+#define NT35510_P1_BT2CTR 0xB7
+#define NT35510_P1_BT3CTR 0xB8
+#define NT35510_P1_BT4CTR 0xB9 /* VGH boosting times/freq */
+#define NT35510_P1_BT5CTR 0xBA
+#define NT35510_P1_PFMCTR 0xBB
+#define NT35510_P1_SETVGP 0xBC
+#define NT35510_P1_SETVGN 0xBD
+#define NT35510_P1_SETVCMOFF 0xBE
+#define NT35510_P1_VGHCTR 0xBF /* VGH output ctrl */
+#define NT35510_P1_SET_GAMMA_RED_POS 0xD1
+#define NT35510_P1_SET_GAMMA_GREEN_POS 0xD2
+#define NT35510_P1_SET_GAMMA_BLUE_POS 0xD3
+#define NT35510_P1_SET_GAMMA_RED_NEG 0xD4
+#define NT35510_P1_SET_GAMMA_GREEN_NEG 0xD5
+#define NT35510_P1_SET_GAMMA_BLUE_NEG 0xD6
+
+/* AVDD and AVEE setting 3 bytes */
+#define NT35510_P1_AVDD_LEN 3
+#define NT35510_P1_AVEE_LEN 3
+#define NT35510_P1_VGH_LEN 3
+#define NT35510_P1_VGL_LEN 3
+#define NT35510_P1_VGP_LEN 3
+#define NT35510_P1_VGN_LEN 3
+/* BT1CTR thru BT5CTR setting 3 bytes */
+#define NT35510_P1_BT1CTR_LEN 3
+#define NT35510_P1_BT2CTR_LEN 3
+#define NT35510_P1_BT4CTR_LEN 3
+#define NT35510_P1_BT5CTR_LEN 3
+/* 52 gamma parameters times two per color: positive and negative */
+#define NT35510_P1_GAMMA_LEN 52
+
+/**
+ * struct nt35510_config - the display-specific NT35510 configuration
+ *
+ * Some of the settings provide an array of bytes, A, B C which mean:
+ * A = normal / idle off mode
+ * B = idle on mode
+ * C = partial / idle off mode
+ *
+ * Gamma correction arrays are 10bit numbers, two consecutive bytes
+ * makes out one point on the gamma correction curve. The points are
+ * not linearly placed along the X axis, we get points 0, 1, 3, 5
+ * 7, 11, 15, 23, 31, 47, 63, 95, 127, 128, 160, 192, 208, 224, 232,
+ * 240, 244, 248, 250, 252, 254, 255. The voltages tuples form
+ * V0, V1, V3 ... V255, with 0x0000 being the lowest voltage and
+ * 0x03FF being the highest voltage.
+ *
+ * Each value must be strictly higher than the previous value forming
+ * a rising curve like this:
+ *
+ * ^
+ * |                                        V255
+ * |                                 V254
+ * |                         ....
+ * |                    V5
+ * |           V3
+ * |     V1
+ * | V0
+ * +------------------------------------------->
+ *
+ * The details about all settings can be found in the NT35510 Application
+ * Note.
+ */
+struct nt35510_config {
+	/**
+	 * @width_mm: physical panel width [mm]
+	 */
+	u32 width_mm;
+	/**
+	 * @height_mm: physical panel height [mm]
+	 */
+	u32 height_mm;
+	/**
+	 * @mode: the display mode. This is only relevant outside the panel
+	 * in video mode: in command mode this is configuring the internal
+	 * timing in the display controller.
+	 */
+	const struct drm_display_mode mode;
+	/**
+	 * @avdd: setting for AVDD ranging from 0x00 = 6.5V to 0x14 = 4.5V
+	 * in 0.1V steps the default is 0x05 which means 6.0V
+	 */
+	u8 avdd[NT35510_P1_AVDD_LEN];
+	/**
+	 * @bt1ctr: setting for boost power control for the AVDD step-up
+	 * circuit (1)
+	 * bits 0..2 in the lower nibble controls PCK, the booster clock
+	 * frequency for the step-up circuit:
+	 * 0 = Hsync/32
+	 * 1 = Hsync/16
+	 * 2 = Hsync/8
+	 * 3 = Hsync/4
+	 * 4 = Hsync/2
+	 * 5 = Hsync
+	 * 6 = Hsync x 2
+	 * 7 = Hsync x 4
+	 * bits 4..6 in the upper nibble controls BTP, the boosting
+	 * amplification for the the step-up circuit:
+	 * 0 = Disable
+	 * 1 = 1.5 x VDDB
+	 * 2 = 1.66 x VDDB
+	 * 3 = 2 x VDDB
+	 * 4 = 2.5 x VDDB
+	 * 5 = 3 x VDDB
+	 * The defaults are 4 and 4 yielding 0x44
+	 */
+	u8 bt1ctr[NT35510_P1_BT1CTR_LEN];
+	/**
+	 * @avee: setting for AVEE ranging from 0x00 = -6.5V to 0x14 = -4.5V
+	 * in 0.1V steps the default is 0x05 which means -6.0V
+	 */
+	u8 avee[NT35510_P1_AVEE_LEN];
+	/**
+	 * @bt2ctr: setting for boost power control for the AVEE step-up
+	 * circuit (2)
+	 * bits 0..2 in the lower nibble controls NCK, the booster clock
+	 * frequency, the values are the same as for PCK in @bt1ctr.
+	 * bits 4..5 in the upper nibble controls BTN, the boosting
+	 * amplification for the the step-up circuit.
+	 * 0 = Disable
+	 * 1 = -1.5 x VDDB
+	 * 2 = -2 x VDDB
+	 * 3 = -2.5 x VDDB
+	 * 4 = -3 x VDDB
+	 * The defaults are 4 and 3 yielding 0x34
+	 */
+	u8 bt2ctr[NT35510_P1_BT2CTR_LEN];
+	/**
+	 * @vgh: setting for VGH ranging from 0x00 = 7.0V to 0x0B = 18.0V
+	 * in 1V steps, the default is 0x08 which means 15V
+	 */
+	u8 vgh[NT35510_P1_VGH_LEN];
+	/**
+	 * @bt4ctr: setting for boost power control for the VGH step-up
+	 * circuit (4)
+	 * bits 0..2 in the lower nibble controls HCK, the booster clock
+	 * frequency, the values are the same as for PCK in @bt1ctr.
+	 * bits 4..5 in the upper nibble controls BTH, the boosting
+	 * amplification for the the step-up circuit.
+	 * 0 = AVDD + VDDB
+	 * 1 = AVDD - AVEE
+	 * 2 = AVDD - AVEE + VDDB
+	 * 3 = AVDD x 2 - AVEE
+	 * The defaults are 4 and 3 yielding 0x34
+	 */
+	u8 bt4ctr[NT35510_P1_BT4CTR_LEN];
+	/**
+	 * @vgl: setting for VGL ranging from 0x00 = -2V to 0x0f = -15V in
+	 * 1V steps, the default is 0x08 which means -10V
+	 */
+	u8 vgl[NT35510_P1_VGL_LEN];
+	/**
+	 * @bt5ctr: setting for boost power control for the VGL step-up
+	 * circuit (5)
+	 * bits 0..2 in the lower nibble controls LCK, the booster clock
+	 * frequency, the values are the same as for PCK in @bt1ctr.
+	 * bits 4..5 in the upper nibble controls BTL, the boosting
+	 * amplification for the the step-up circuit.
+	 * 0 = AVEE + VCL
+	 * 1 = AVEE - AVDD
+	 * 2 = AVEE + VCL - AVDD
+	 * 3 = AVEE x 2 - AVDD
+	 * The defaults are 3 and 2 yielding 0x32
+	 */
+	u8 bt5ctr[NT35510_P1_BT5CTR_LEN];
+	/**
+	 * @vgp: setting for VGP, the positive gamma divider voltages
+	 * VGMP the high voltage and VGSP the low voltage.
+	 * The first byte contains bit 8 of VGMP and VGSP in bits 4 and 0
+	 * The second byte contains bit 0..7 of VGMP
+	 * The third byte contains bit 0..7 of VGSP
+	 * VGMP 0x00 = 3.0V .. 0x108 = 6.3V in steps of 12.5mV
+	 * VGSP 0x00 = 0V .. 0x111 = 3.7V in steps of 12.5mV
+	 */
+	u8 vgp[NT35510_P1_VGP_LEN];
+	/**
+	 * @vgn: setting for VGN, the negative gamma divider voltages,
+	 * same layout of bytes as @vgp.
+	 */
+	u8 vgn[NT35510_P1_VGN_LEN];
+	/**
+	 * @sdeqctr: Source driver control settings, first byte is
+	 * 0 for mode 1 and 1 for mode 2. Mode 1 uses two steps and
+	 * mode 2 uses three steps meaning EQS3 is not used in mode
+	 * 1. Mode 2 is default. The last three parameters are EQS1, EQS2
+	 * and EQS3, setting the rise time for each equalizer step:
+	 * 0x00 = 0.0 us to 0x0f = 7.5 us in steps of 0.5us. The default
+	 * is 0x07 = 3.5 us.
+	 */
+	u8 sdeqctr[NT35510_P0_SDEQCTR_LEN];
+	/**
+	 * @sdvpctr: power/voltage behaviour during vertical porch time
+	 */
+	u8 sdvpctr;
+	/**
+	 * @t1: the number of pixel clocks on one scanline, range
+	 * 0x100 (258 ticks) .. 0x3FF (1024 ticks) so the value + 1
+	 * clock ticks.
+	 */
+	u16 t1;
+	/**
+	 * @vbp: vertical back porch toward the PANEL note: not toward
+	 * the DSI host; these are separate interfaces, in from DSI host
+	 * and out to the panel.
+	 */
+	u8 vbp;
+	/**
+	 * @vfp: vertical front porch toward the PANEL.
+	 */
+	u8 vfp;
+	/**
+	 * @psel: pixel clock divisor: 0 = 1, 1 = 2, 2 = 4, 3 = 8.
+	 */
+	u8 psel;
+	/**
+	 * @dpmctr12: Display timing control 12
+	 * Byte 1 bit 4 selects LVGL voltage level: 0 = VGLX, 1 = VGL_REG
+	 * Byte 1 bit 1 selects gate signal mode: 0 = non-overlap, 1 = overlap
+	 * Byte 1 bit 0 selects output signal control R/L swap, 0 = normal
+	 * 1 = swap all O->E, L->R
+	 * Byte 2 is CLW delay clock for CK O/E and CKB O/E signals:
+	 * 0x00 = 0us .. 0xFF = 12.75us in 0.05us steps
+	 * Byte 3 is FTI_H0 delay time for STP O/E signals:
+	 * 0x00 = 0us .. 0xFF = 12.75us in 0.05us steps
+	 */
+	u8 dpmctr12[NT35510_P0_DPMCTR12_LEN];
+	/**
+	 * @gamma_corr_pos_r: Red gamma correction parameters, positive
+	 */
+	u8 gamma_corr_pos_r[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_pos_g: Green gamma correction parameters, positive
+	 */
+	u8 gamma_corr_pos_g[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_pos_b: Blue gamma correction parameters, positive
+	 */
+	u8 gamma_corr_pos_b[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_neg_r: Red gamma correction parameters, negative
+	 */
+	u8 gamma_corr_neg_r[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_neg_g: Green gamma correction parameters, negative
+	 */
+	u8 gamma_corr_neg_g[NT35510_P1_GAMMA_LEN];
+	/**
+	 * @gamma_corr_neg_b: Blue gamma correction parameters, negative
+	 */
+	u8 gamma_corr_neg_b[NT35510_P1_GAMMA_LEN];
+};
+
+/**
+ * struct nt35510 - state container for the NT35510 panel
+ */
+struct nt35510 {
+	/**
+	 * @dev: the container device
+	 */
+	struct device *dev;
+	/**
+	 * @conf: the specific panel configuration, as the NT35510
+	 * can be combined with many physical panels, they can have
+	 * different physical dimensions and gamma correction etc,
+	 * so this is stored in the config.
+	 */
+	const struct nt35510_config *conf;
+	/**
+	 * @panel: the DRM panel object for the instance
+	 */
+	struct drm_panel panel;
+	/**
+	 * @supplies: regulators supplying the panel
+	 */
+	struct regulator_bulk_data supplies[2];
+	/**
+	 * @reset_gpio: the reset line
+	 */
+	struct gpio_desc *reset_gpio;
+};
+
+/* Manufacturer command has strictly this byte sequence */
+static const u8 nt35510_mauc_select_page_0[] = { 0x55, 0xAA, 0x52, 0x08, 0x00 };
+static const u8 nt35510_mauc_select_page_1[] = { 0x55, 0xAA, 0x52, 0x08, 0x01 };
+static const u8 nt35510_vgh_on[] = { 0x01 };
+
+static inline struct nt35510 *panel_to_nt35510(struct drm_panel *panel)
+{
+	return container_of(panel, struct nt35510, panel);
+}
+
+#define NT35510_ROTATE_0_SETTING	0x02
+#define NT35510_ROTATE_180_SETTING	0x00
+
+static int nt35510_send_long(struct nt35510 *nt, struct mipi_dsi_device *dsi,
+			     u8 cmd, u8 cmdlen, const u8 *seq)
+{
+	const u8 *seqp = seq;
+	int cmdwritten = 0;
+	int chunk = cmdlen;
+	int ret;
+
+	if (chunk > 15)
+		chunk = 15;
+	ret = mipi_dsi_dcs_write(dsi, cmd, seqp, chunk);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev,
+			      "error sending DCS command seq cmd %02x\n",
+			      cmd);
+		return ret;
+	}
+	cmdwritten += chunk;
+	seqp += chunk;
+
+	while (cmdwritten < cmdlen) {
+		chunk = cmdlen - cmdwritten;
+		if (chunk > 15)
+			chunk = 15;
+		ret = mipi_dsi_generic_write(dsi, seqp, chunk);
+		if (ret < 0) {
+			DRM_DEV_ERROR(nt->dev,
+				      "error sending generic write seq %02x\n",
+				      cmd);
+			return ret;
+		}
+		cmdwritten += chunk;
+		seqp += chunk;
+	}
+	DRM_DEV_DEBUG(nt->dev, "sent command %02x %02x bytes\n",
+		      cmd, cmdlen);
+	return 0;
+}
+
+static int nt35510_read_id(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	u8 id1, id2, id3;
+	int ret;
+
+	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID1, &id1, 1);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev, "could not read MTP ID1\n");
+		return ret;
+	}
+	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID2, &id2, 1);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev, "could not read MTP ID2\n");
+		return ret;
+	}
+	ret = mipi_dsi_dcs_read(dsi, MCS_CMD_READ_ID3, &id3, 1);
+	if (ret < 0) {
+		DRM_DEV_ERROR(nt->dev, "could not read MTP ID3\n");
+		return ret;
+	}
+
+	/*
+	 * Multi-Time Programmable (?) memory contains manufacturer
+	 * ID (e.g. Hydis 0x55), driver ID (e.g. NT35510 0xc0) and
+	 * version.
+	 */
+	DRM_DEV_INFO(nt->dev,
+		     "MTP ID manufacturer: %02x version: %02x driver: %02x\n",
+		     id1, id2, id3);
+
+	return 0;
+}
+
+/**
+ * nt35510_setup_power() - set up power config in page 1
+ * @nt: the display instance to set up
+ */
+static int nt35510_setup_power(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETAVDD,
+				NT35510_P1_AVDD_LEN,
+				nt->conf->avdd);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT1CTR,
+				NT35510_P1_BT1CTR_LEN,
+				nt->conf->bt1ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETAVEE,
+				NT35510_P1_AVEE_LEN,
+				nt->conf->avee);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT2CTR,
+				NT35510_P1_BT2CTR_LEN,
+				nt->conf->bt2ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGH,
+				NT35510_P1_VGH_LEN,
+				nt->conf->vgh);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT4CTR,
+				NT35510_P1_BT4CTR_LEN,
+				nt->conf->bt4ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_VGHCTR,
+				ARRAY_SIZE(nt35510_vgh_on),
+				nt35510_vgh_on);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGL,
+				NT35510_P1_VGL_LEN,
+				nt->conf->vgl);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_BT5CTR,
+				NT35510_P1_BT5CTR_LEN,
+				nt->conf->bt5ctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGP,
+				NT35510_P1_VGP_LEN,
+				nt->conf->vgp);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SETVGN,
+				NT35510_P1_VGN_LEN,
+				nt->conf->vgn);
+	if (ret)
+		return ret;
+
+	/* Typically 10 ms */
+	usleep_range(10000, 20000);
+
+	return 0;
+}
+
+/**
+ * nt35510_setup_display() - set up display config in page 0
+ * @nt: the display instance to set up
+ */
+static int nt35510_setup_display(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	const struct nt35510_config *conf = nt->conf;
+	u8 dopctr[NT35510_P0_DOPCTR_LEN];
+	u8 gseqctr[NT35510_P0_GSEQCTR_LEN];
+	u8 dpfrctr[NT35510_P0_DPFRCTR1_LEN];
+	/* FIXME: set up any rotation (assume none for now) */
+	u8 addr_mode = NT35510_ROTATE_0_SETTING;
+	u8 val;
+	int ret;
+
+	/* Enable TE, EoTP and RGB pixel format */
+	dopctr[0] = NT35510_DOPCTR_0_DSITE | NT35510_DOPCTR_0_EOTP |
+		NT35510_DOPCTR_0_N565;
+	dopctr[1] = NT35510_DOPCTR_1_CTB;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DOPCTR,
+				NT35510_P0_DOPCTR_LEN,
+				dopctr);
+	if (ret)
+		return ret;
+
+	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_ADDRESS_MODE, &addr_mode,
+				 sizeof(addr_mode));
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Source data hold time, default 0x05 = 2.5us
+	 * 0x00..0x3F = 0 .. 31.5us in steps of 0.5us
+	 * 0x0A = 5us
+	 */
+	val = 0x0A;
+	ret = mipi_dsi_dcs_write(dsi, NT35510_P0_SDHDTCTR, &val,
+				 sizeof(val));
+	if (ret < 0)
+		return ret;
+
+	/* EQ control for gate signals, 0x00 = 0 us */
+	gseqctr[0] = 0x00;
+	gseqctr[1] = 0x00;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_GSEQCTR,
+				NT35510_P0_GSEQCTR_LEN,
+				gseqctr);
+	if (ret)
+		return ret;
+
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_SDEQCTR,
+				NT35510_P0_SDEQCTR_LEN,
+				conf->sdeqctr);
+	if (ret)
+		return ret;
+
+	ret = mipi_dsi_dcs_write(dsi, NT35510_P0_SDVPCTR,
+				 &conf->sdvpctr, 1);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Display timing control for active and idle off mode:
+	 * the first byte contains
+	 * the two high bits of T1A and second byte the low 8 bits, and
+	 * the valid range is 0x100 (257) to 0x3ff (1023) representing
+	 * 258..1024 (+1) pixel clock ticks for one scanline. At 20MHz pixel
+	 * clock this covers the range of 12.90us .. 51.20us in steps of
+	 * 0.05us, the default is 0x184 (388) representing 389 ticks.
+	 * The third byte is VBPDA, vertical back porch display active
+	 * and the fourth VFPDA, vertical front porch display active,
+	 * both given in number of scanlines in the range 0x02..0xff
+	 * for 2..255 scanlines. The fifth byte is 2 bits selecting
+	 * PSEL for active and idle off mode, how much the 20MHz clock
+	 * is divided by 0..3.  This needs to be adjusted to get the right
+	 * frame rate.
+	 */
+	dpfrctr[0] = (conf->t1 >> 8) & 0xFF;
+	dpfrctr[1] = conf->t1 & 0xFF;
+	/* Vertical back porch */
+	dpfrctr[2] = conf->vbp;
+	/* Vertical front porch */
+	dpfrctr[3] = conf->vfp;
+	dpfrctr[4] = conf->psel;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR1,
+				NT35510_P0_DPFRCTR1_LEN,
+				dpfrctr);
+	if (ret)
+		return ret;
+	/* For idle and partial idle off mode we decrease front porch by one */
+	dpfrctr[3]--;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR2,
+				NT35510_P0_DPFRCTR2_LEN,
+				dpfrctr);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPFRCTR3,
+				NT35510_P0_DPFRCTR3_LEN,
+				dpfrctr);
+	if (ret)
+		return ret;
+
+	/* Enable TE on vblank */
+	ret = mipi_dsi_dcs_set_tear_on(dsi, MIPI_DSI_DCS_TEAR_MODE_VBLANK);
+	if (ret)
+		return ret;
+
+	/* Turn on the pads? */
+	ret = nt35510_send_long(nt, dsi, NT35510_P0_DPMCTR12,
+				NT35510_P0_DPMCTR12_LEN,
+				conf->dpmctr12);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int nt35510_set_brightness(struct backlight_device *bl)
+{
+	struct nt35510 *nt = bl_get_data(bl);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	u8 brightness = bl->props.brightness;
+	int ret;
+
+	DRM_DEV_DEBUG(nt->dev, "set brightness %d\n", brightness);
+	ret = mipi_dsi_dcs_write(dsi, MIPI_DCS_SET_DISPLAY_BRIGHTNESS,
+				 &brightness,
+				 sizeof(brightness));
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static const struct backlight_ops nt35510_bl_ops = {
+	.update_status = nt35510_set_brightness,
+};
+
+/*
+ * This power-on sequence
+ */
+static int nt35510_power_on(struct nt35510 *nt)
+{
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(nt->supplies), nt->supplies);
+	if (ret < 0) {
+		dev_err(nt->dev, "unable to enable regulators\n");
+		return ret;
+	}
+
+	/* Toggle RESET in accordance with datasheet page 370 */
+	if (nt->reset_gpio) {
+		gpiod_set_value(nt->reset_gpio, 1);
+		/* Active min 10 us according to datasheet, let's say 20 */
+		usleep_range(20, 1000);
+		gpiod_set_value(nt->reset_gpio, 0);
+		/*
+		 * 5 ms during sleep mode, 120 ms during sleep out mode
+		 * according to datasheet, let's use 120-140 ms.
+		 */
+		usleep_range(120000, 140000);
+	}
+
+	ret = nt35510_read_id(nt);
+	if (ret)
+		return ret;
+
+	/* Set up stuff in  manufacturer control, page 1 */
+	ret = nt35510_send_long(nt, dsi, MCS_CMD_MAUCCTR,
+				ARRAY_SIZE(nt35510_mauc_select_page_1),
+				nt35510_mauc_select_page_1);
+	if (ret)
+		return ret;
+
+	ret = nt35510_setup_power(nt);
+	if (ret)
+		return ret;
+
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_RED_POS,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_pos_r);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_GREEN_POS,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_pos_g);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_BLUE_POS,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_pos_b);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_RED_NEG,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_neg_r);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_GREEN_NEG,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_neg_g);
+	if (ret)
+		return ret;
+	ret = nt35510_send_long(nt, dsi, NT35510_P1_SET_GAMMA_BLUE_NEG,
+				NT35510_P1_GAMMA_LEN,
+				nt->conf->gamma_corr_neg_b);
+	if (ret)
+		return ret;
+
+	/* Set up stuff in  manufacturer control, page 0 */
+	ret = nt35510_send_long(nt, dsi, MCS_CMD_MAUCCTR,
+				ARRAY_SIZE(nt35510_mauc_select_page_0),
+				nt35510_mauc_select_page_0);
+	if (ret)
+		return ret;
+
+	ret = nt35510_setup_display(nt);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int nt35510_power_off(struct nt35510 *nt)
+{
+	int ret;
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(nt->supplies), nt->supplies);
+	if (ret)
+		return ret;
+
+	if (nt->reset_gpio)
+		gpiod_set_value(nt->reset_gpio, 1);
+
+	return 0;
+}
+
+static int nt35510_unprepare(struct drm_panel *panel)
+{
+	struct nt35510 *nt = panel_to_nt35510(panel);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = mipi_dsi_dcs_set_display_off(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to turn display off (%d)\n",
+			      ret);
+		return ret;
+	}
+	usleep_range(10000, 20000);
+
+	/* Enter sleep mode */
+	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to enter sleep mode (%d)\n",
+			      ret);
+		return ret;
+	}
+
+	/* Wait 4 frames, how much is that 5ms in the vendor driver */
+	usleep_range(5000, 10000);
+
+	ret = nt35510_power_off(nt);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int nt35510_prepare(struct drm_panel *panel)
+{
+	struct nt35510 *nt = panel_to_nt35510(panel);
+	struct mipi_dsi_device *dsi = to_mipi_dsi_device(nt->dev);
+	int ret;
+
+	ret = nt35510_power_on(nt);
+	if (ret)
+		return ret;
+
+	/* Exit sleep mode */
+	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to exit sleep mode (%d)\n",
+			      ret);
+		return ret;
+	}
+	/* Up to 120 ms */
+	usleep_range(120000, 150000);
+
+	ret = mipi_dsi_dcs_set_display_on(dsi);
+	if (ret) {
+		DRM_DEV_ERROR(nt->dev, "failed to turn display on (%d)\n",
+			      ret);
+		return ret;
+	}
+	/* Some 10 ms */
+	usleep_range(10000, 20000);
+
+	return 0;
+}
+
+static int nt35510_get_modes(struct drm_panel *panel,
+			     struct drm_connector *connector)
+{
+	struct nt35510 *nt = panel_to_nt35510(panel);
+	struct drm_display_mode *mode;
+	struct drm_display_info *info;
+
+	info = &connector->display_info;
+	info->width_mm = nt->conf->width_mm;
+	info->height_mm = nt->conf->height_mm;
+	mode = drm_mode_duplicate(connector->dev, &nt->conf->mode);
+	if (!mode) {
+		DRM_ERROR("bad mode or failed to add mode\n");
+		return -EINVAL;
+	}
+	drm_mode_set_name(mode);
+	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
+
+	mode->width_mm = nt->conf->width_mm;
+	mode->height_mm = nt->conf->height_mm;
+	drm_mode_probed_add(connector, mode);
+
+	return 1; /* Number of modes */
+}
+
+static const struct drm_panel_funcs nt35510_drm_funcs = {
+	.unprepare = nt35510_unprepare,
+	.prepare = nt35510_prepare,
+	.get_modes = nt35510_get_modes,
+};
+
+static int nt35510_probe(struct mipi_dsi_device *dsi)
+{
+	struct device *dev = &dsi->dev;
+	struct nt35510 *nt;
+	int ret;
+
+	nt = devm_kzalloc(dev, sizeof(struct nt35510), GFP_KERNEL);
+	if (!nt)
+		return -ENOMEM;
+	mipi_dsi_set_drvdata(dsi, nt);
+	nt->dev = dev;
+
+	dsi->lanes = 2;
+	dsi->format = MIPI_DSI_FMT_RGB888;
+	/*
+	 * Datasheet suggests max HS rate for NT35510 is 250 MHz
+	 * (period time 4ns, see figure 7.6.4 page 365) and max LP rate is
+	 * 20 MHz (period time 50ns, see figure 7.6.6. page 366).
+	 * However these frequencies appear in source code for the Hydis
+	 * HVA40WV1 panel and setting up the LP frequency makes the panel
+	 * not work.
+	 *
+	 * TODO: if other panels prove to be closer to the datasheet,
+	 * maybe make this a per-panel config in struct nt35510_config?
+	 */
+	dsi->hs_rate = 349440000;
+	dsi->lp_rate = 9600000;
+	dsi->mode_flags = MIPI_DSI_CLOCK_NON_CONTINUOUS |
+		MIPI_DSI_MODE_EOT_PACKET;
+
+	/*
+	 * Every new incarnation of this display must have a unique
+	 * data entry for the system in this driver.
+	 */
+	nt->conf = of_device_get_match_data(dev);
+	if (!nt->conf) {
+		dev_err(dev, "missing device configuration\n");
+		return -ENODEV;
+	}
+
+	nt->supplies[0].supply = "vdd"; /* 2.3-4.8 V */
+	nt->supplies[1].supply = "vddi"; /* 1.65-3.3V */
+	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(nt->supplies),
+				      nt->supplies);
+	if (ret < 0)
+		return ret;
+	ret = regulator_set_voltage(nt->supplies[0].consumer,
+				    2300000, 4800000);
+	if (ret)
+		return ret;
+	ret = regulator_set_voltage(nt->supplies[1].consumer,
+				    1650000, 3300000);
+	if (ret)
+		return ret;
+
+	nt->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_ASIS);
+	if (IS_ERR(nt->reset_gpio)) {
+		dev_err(dev, "error getting RESET GPIO\n");
+		return PTR_ERR(nt->reset_gpio);
+	}
+
+	drm_panel_init(&nt->panel, dev, &nt35510_drm_funcs,
+		       DRM_MODE_CONNECTOR_DSI);
+
+	/*
+	 * First, try to locate an external backlight (such as on GPIO)
+	 * if this fails, assume we will want to use the internal backlight
+	 * control.
+	 */
+	ret = drm_panel_of_backlight(&nt->panel);
+	if (ret) {
+		dev_err(dev, "error getting external backlight %d\n", ret);
+		return ret;
+	}
+	if (!nt->panel.backlight) {
+		struct backlight_device *bl;
+
+		bl = devm_backlight_device_register(dev, "nt35510", dev, nt,
+						    &nt35510_bl_ops, NULL);
+		if (IS_ERR(bl)) {
+			DRM_DEV_ERROR(dev, "failed to register backlight device\n");
+			return PTR_ERR(bl);
+		}
+		bl->props.max_brightness = 255;
+		bl->props.brightness = 255;
+		bl->props.power = FB_BLANK_POWERDOWN;
+		nt->panel.backlight = bl;
+	}
+
+	ret = drm_panel_add(&nt->panel);
+	if (ret < 0)
+		return ret;
+
+	ret = mipi_dsi_attach(dsi);
+	if (ret < 0)
+		drm_panel_remove(&nt->panel);
+
+	return 0;
+}
+
+static int nt35510_remove(struct mipi_dsi_device *dsi)
+{
+	struct nt35510 *nt = mipi_dsi_get_drvdata(dsi);
+	int ret;
+
+	mipi_dsi_detach(dsi);
+	/* Power off */
+	ret = nt35510_power_off(nt);
+	drm_panel_remove(&nt->panel);
+
+	return ret;
+}
+
+/*
+ * These gamma correction values are 10bit tuples, so only bits 0 and 1 is
+ * ever used in the first byte. They form a positive and negative gamma
+ * correction curve for each color, values must be strictly higher for each
+ * step on the curve. As can be seen these default curves goes from 0x0001
+ * to 0x03FE.
+ */
+#define NT35510_GAMMA_POS_DEFAULT 0x00, 0x01, 0x00, 0x43, 0x00, \
+		0x6B, 0x00, 0x87, 0x00, 0xA3, 0x00, 0xCE, 0x00, 0xF1, 0x01, \
+		0x27, 0x01, 0x53, 0x01, 0x98, 0x01, 0xCE, 0x02, 0x22, 0x02, \
+		0x83, 0x02, 0x78, 0x02, 0x9E, 0x02, 0xDD, 0x03, 0x00, 0x03, \
+		0x2E, 0x03, 0x54, 0x03, 0x7F, 0x03, 0x95, 0x03, 0xB3, 0x03, \
+		0xC2, 0x03, 0xE1, 0x03, 0xF1, 0x03, 0xFE
+
+#define NT35510_GAMMA_NEG_DEFAULT 0x00, 0x01, 0x00, 0x43, 0x00, \
+		0x6B, 0x00, 0x87, 0x00, 0xA3, 0x00, 0xCE, 0x00, 0xF1, 0x01, \
+		0x27, 0x01, 0x53, 0x01, 0x98, 0x01, 0xCE, 0x02, 0x22, 0x02, \
+		0x43, 0x02, 0x50, 0x02, 0x9E, 0x02, 0xDD, 0x03, 0x00, 0x03, \
+		0x2E, 0x03, 0x54, 0x03, 0x7F, 0x03, 0x95, 0x03, 0xB3, 0x03, \
+		0xC2, 0x03, 0xE1, 0x03, 0xF1, 0x03, 0xFE
+
+/*
+ * The Hydis HVA40WV1 panel
+ */
+static const struct nt35510_config nt35510_hydis_hva40wv1 = {
+	.width_mm = 52,
+	.height_mm = 86,
+	/**
+	 * As the Hydis panel is used in command mode, the porches etc
+	 * are settings programmed internally into the NT35510 controller
+	 * and generated toward the physical display. As the panel is not
+	 * used in video mode, these are not really exposed to the DSI
+	 * host.
+	 *
+	 * Display frame rate control:
+	 * Frame rate = (20 MHz / 1) / (389 * (7 + 50 + 800)) ~= 60 Hz
+	 */
+	.mode = {
+		/* The internal pixel clock of the NT35510 is 20 MHz */
+		.clock = 20000000,
+		.hdisplay = 480,
+		.hsync_start = 480 + 2, /* HFP = 2 */
+		.hsync_end = 480 + 2 + 0, /* HSync = 0 */
+		.htotal = 480 + 2 + 0 + 5, /* HFP = 5 */
+		.vdisplay = 800,
+		.vsync_start = 800 + 2, /* VFP = 2 */
+		.vsync_end = 800 + 2 + 0, /* VSync = 0 */
+		.vtotal = 800 + 2 + 0 + 5, /* VBP = 5 */
+		.vrefresh = 60, /* Calculated */
+		.flags = 0,
+	},
+	/* 0x09: AVDD = 5.6V */
+	.avdd = { 0x09, 0x09, 0x09 },
+	/* 0x34: PCK = Hsync/2, BTP = 2 x VDDB */
+	.bt1ctr = { 0x34, 0x34, 0x34 },
+	/* 0x09: AVEE = -5.6V */
+	.avee = { 0x09, 0x09, 0x09 },
+	/* 0x24: NCK = Hsync/2, BTN =  -2 x VDDB */
+	.bt2ctr = { 0x24, 0x24, 0x24 },
+	/* 0x05 = 12V */
+	.vgh = { 0x05, 0x05, 0x05 },
+	/* 0x24: NCKA = Hsync/2, VGH = 2 x AVDD - AVEE */
+	.bt4ctr = { 0x24, 0x24, 0x24 },
+	/* 0x0B = -13V */
+	.vgl = { 0x0B, 0x0B, 0x0B },
+	/* 0x24: LCKA = Hsync, VGL = AVDD + VCL - AVDD */
+	.bt5ctr = { 0x24, 0x24, 0x24 },
+	/* VGMP: 0x0A3 = 5.0375V, VGSP = 0V */
+	.vgp = { 0x00, 0xA3, 0x00 },
+	/* VGMP: 0x0A3 = 5.0375V, VGSP = 0V */
+	.vgn = { 0x00, 0xA3, 0x00 },
+	/* SDEQCTR: source driver EQ mode 2, 2.5 us rise time on each step */
+	.sdeqctr = { 0x01, 0x05, 0x05, 0x05 },
+	/* SDVPCTR: Normal operation off color during v porch */
+	.sdvpctr = 0x01,
+	/* T1: number of pixel clocks on one scanline: 0x184 = 389 clocks */
+	.t1 = 0x0184,
+	/* VBP: vertical back porch toward the panel */
+	.vbp = 7,
+	/* VFP: vertical front porch toward the panel */
+	.vfp = 50,
+	/* PSEL: divide pixel clock 20MHz with 1 (no clock downscaling) */
+	.psel = 0,
+	/* DPTMCTR12: 0x03: LVGL = VGLX, overlap mode, swap R->L O->E */
+	.dpmctr12 = { 0x03, 0x00, 0x00, },
+	/* Default gamma correction values */
+	.gamma_corr_pos_r = { NT35510_GAMMA_POS_DEFAULT },
+	.gamma_corr_pos_g = { NT35510_GAMMA_POS_DEFAULT },
+	.gamma_corr_pos_b = { NT35510_GAMMA_POS_DEFAULT },
+	.gamma_corr_neg_r = { NT35510_GAMMA_NEG_DEFAULT },
+	.gamma_corr_neg_g = { NT35510_GAMMA_NEG_DEFAULT },
+	.gamma_corr_neg_b = { NT35510_GAMMA_NEG_DEFAULT },
+};
+
+static const struct of_device_id nt35510_of_match[] = {
+	{
+		.compatible = "hydis,hva40wv1",
+		.data = &nt35510_hydis_hva40wv1,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, nt35510_of_match);
+
+static struct mipi_dsi_driver nt35510_driver = {
+	.probe = nt35510_probe,
+	.remove = nt35510_remove,
+	.driver = {
+		.name = "panel-novatek-nt35510",
+		.of_match_table = nt35510_of_match,
+	},
+};
+module_mipi_dsi_driver(nt35510_driver);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");
+MODULE_DESCRIPTION("NT35510-based panel driver");
+MODULE_LICENSE("GPL v2");
-- 
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