backlight: otm3225a: Add support for ORISE OTM3225A LCD SoC

This patch adds a LCD driver supporting the OTM3225A LCD SoC
from ORISE Technology. This device can drive TFT LC panels having a
resolution of 240x320 pixels. After initializing the OTM3225A using
it's SPI interface it switches to use 16-bib RGB as external
display interface.

Signed-off-by: Felix Brack <[e-mail]>
Acked-by: Daniel Thompson <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/video/backlight/Kconfig

···
 	  If you have a HX-8357 LCD panel, say Y to enable its LCD control
 	  driver.
 
+  config LCD_OTM3225A
+  	tristate "ORISE Technology OTM3225A support"
+  	depends on SPI
+  	help
+  	  If you have a panel based on the OTM3225A controller
+  	  chip then say y to include a driver for it.
+
 endif # LCD_CLASS_DEVICE
 
 #

drivers/video/backlight/Makefile

···
 obj-$(CONFIG_LCD_LMS283GF05)		+= lms283gf05.o
 obj-$(CONFIG_LCD_LMS501KF03)		+= lms501kf03.o
 obj-$(CONFIG_LCD_LTV350QV)		+= ltv350qv.o
+obj-$(CONFIG_LCD_OTM3225A)		+= otm3225a.o
 obj-$(CONFIG_LCD_PLATFORM)		+= platform_lcd.o
 obj-$(CONFIG_LCD_S6E63M0)		+= s6e63m0.o
 obj-$(CONFIG_LCD_TDO24M)		+= tdo24m.o

drivers/video/backlight/otm3225a.c

···
+// SPDX-License-Identifier: GPL-2.0
+/* Driver for ORISE Technology OTM3225A SOC for TFT LCD
+ * Copyright (C) 2017, EETS GmbH, Felix Brack <[e-mail]>
+ *
+ * This driver implements a lcd device for the ORISE OTM3225A display
+ * controller. The control interface to the display is SPI and the display's
+ * memory is updated over the 16-bit RGB interface.
+ * The main source of information for writing this driver was provided by the
+ * OTM3225A datasheet from ORISE Technology. Some information arise from the
+ * ILI9328 datasheet from ILITEK as well as from the datasheets and sample code
+ * provided by Crystalfontz America Inc. who sells the CFAF240320A-032T, a 3.2"
+ * TFT LC display using the OTM3225A controller.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/lcd.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#define OTM3225A_INDEX_REG	0x70
+#define OTM3225A_DATA_REG	0x72
+
+/* instruction register list */
+#define DRIVER_OUTPUT_CTRL_1	0x01
+#define DRIVER_WAVEFORM_CTRL	0x02
+#define ENTRY_MODE		0x03
+#define SCALING_CTRL		0x04
+#define DISPLAY_CTRL_1		0x07
+#define DISPLAY_CTRL_2		0x08
+#define DISPLAY_CTRL_3		0x09
+#define FRAME_CYCLE_CTRL	0x0A
+#define EXT_DISP_IFACE_CTRL_1	0x0C
+#define FRAME_MAKER_POS		0x0D
+#define EXT_DISP_IFACE_CTRL_2	0x0F
+#define POWER_CTRL_1		0x10
+#define POWER_CTRL_2		0x11
+#define POWER_CTRL_3		0x12
+#define POWER_CTRL_4		0x13
+#define GRAM_ADDR_HORIZ_SET	0x20
+#define GRAM_ADDR_VERT_SET	0x21
+#define GRAM_READ_WRITE		0x22
+#define POWER_CTRL_7		0x29
+#define FRAME_RATE_CTRL		0x2B
+#define GAMMA_CTRL_1		0x30
+#define GAMMA_CTRL_2		0x31
+#define GAMMA_CTRL_3		0x32
+#define GAMMA_CTRL_4		0x35
+#define GAMMA_CTRL_5		0x36
+#define GAMMA_CTRL_6		0x37
+#define GAMMA_CTRL_7		0x38
+#define GAMMA_CTRL_8		0x39
+#define GAMMA_CTRL_9		0x3C
+#define GAMMA_CTRL_10		0x3D
+#define WINDOW_HORIZ_RAM_START	0x50
+#define WINDOW_HORIZ_RAM_END	0x51
+#define WINDOW_VERT_RAM_START	0x52
+#define WINDOW_VERT_RAM_END	0x53
+#define DRIVER_OUTPUT_CTRL_2	0x60
+#define BASE_IMG_DISPLAY_CTRL	0x61
+#define VERT_SCROLL_CTRL	0x6A
+#define PD1_DISPLAY_POS		0x80
+#define PD1_RAM_START		0x81
+#define PD1_RAM_END		0x82
+#define PD2_DISPLAY_POS		0x83
+#define PD2_RAM_START		0x84
+#define PD2_RAM_END		0x85
+#define PANEL_IFACE_CTRL_1	0x90
+#define PANEL_IFACE_CTRL_2	0x92
+#define PANEL_IFACE_CTRL_4	0x95
+#define PANEL_IFACE_CTRL_5	0x97
+
+struct otm3225a_data {
+	struct spi_device *spi;
+	struct lcd_device *ld;
+	int power;
+};
+
+struct otm3225a_spi_instruction {
+	unsigned char reg;	/* register to write */
+	unsigned short value;	/* data to write to 'reg' */
+	unsigned short delay;	/* delay in ms after write */
+};
+
+static struct otm3225a_spi_instruction display_init[] = {
+	{ DRIVER_OUTPUT_CTRL_1,		0x0000, 0 },
+	{ DRIVER_WAVEFORM_CTRL,		0x0700, 0 },
+	{ ENTRY_MODE,			0x50A0, 0 },
+	{ SCALING_CTRL,			0x0000, 0 },
+	{ DISPLAY_CTRL_2,		0x0606, 0 },
+	{ DISPLAY_CTRL_3,		0x0000, 0 },
+	{ FRAME_CYCLE_CTRL,		0x0000, 0 },
+	{ EXT_DISP_IFACE_CTRL_1,	0x0000, 0 },
+	{ FRAME_MAKER_POS,		0x0000, 0 },
+	{ EXT_DISP_IFACE_CTRL_2,	0x0002, 0 },
+	{ POWER_CTRL_2,			0x0007, 0 },
+	{ POWER_CTRL_3,			0x0000, 0 },
+	{ POWER_CTRL_4,			0x0000, 200 },
+	{ DISPLAY_CTRL_1,		0x0101, 0 },
+	{ POWER_CTRL_1,			0x12B0, 0 },
+	{ POWER_CTRL_2,			0x0007, 0 },
+	{ POWER_CTRL_3,			0x01BB, 50 },
+	{ POWER_CTRL_4,			0x0013, 0 },
+	{ POWER_CTRL_7,			0x0010, 50 },
+	{ GAMMA_CTRL_1,			0x000A, 0 },
+	{ GAMMA_CTRL_2,			0x1326, 0 },
+	{ GAMMA_CTRL_3,			0x0A29, 0 },
+	{ GAMMA_CTRL_4,			0x0A0A, 0 },
+	{ GAMMA_CTRL_5,			0x1E03, 0 },
+	{ GAMMA_CTRL_6,			0x031E, 0 },
+	{ GAMMA_CTRL_7,			0x0706, 0 },
+	{ GAMMA_CTRL_8,			0x0303, 0 },
+	{ GAMMA_CTRL_9,			0x010E, 0 },
+	{ GAMMA_CTRL_10,		0x040E, 0 },
+	{ WINDOW_HORIZ_RAM_START,	0x0000, 0 },
+	{ WINDOW_HORIZ_RAM_END,		0x00EF, 0 },
+	{ WINDOW_VERT_RAM_START,	0x0000, 0 },
+	{ WINDOW_VERT_RAM_END,		0x013F, 0 },
+	{ DRIVER_OUTPUT_CTRL_2,		0x2700, 0 },
+	{ BASE_IMG_DISPLAY_CTRL,	0x0001, 0 },
+	{ VERT_SCROLL_CTRL,		0x0000, 0 },
+	{ PD1_DISPLAY_POS,		0x0000, 0 },
+	{ PD1_RAM_START,		0x0000, 0 },
+	{ PD1_RAM_END,			0x0000, 0 },
+	{ PD2_DISPLAY_POS,		0x0000, 0 },
+	{ PD2_RAM_START,		0x0000, 0 },
+	{ PD2_RAM_END,			0x0000, 0 },
+	{ PANEL_IFACE_CTRL_1,		0x0010, 0 },
+	{ PANEL_IFACE_CTRL_2,		0x0000, 0 },
+	{ PANEL_IFACE_CTRL_4,		0x0210, 0 },
+	{ PANEL_IFACE_CTRL_5,		0x0000, 0 },
+	{ DISPLAY_CTRL_1,		0x0133, 0 },
+};
+
+static struct otm3225a_spi_instruction display_enable_rgb_interface[] = {
+	{ ENTRY_MODE,			0x1080, 0 },
+	{ GRAM_ADDR_HORIZ_SET,		0x0000, 0 },
+	{ GRAM_ADDR_VERT_SET,		0x0000, 0 },
+	{ EXT_DISP_IFACE_CTRL_1,	0x0111, 500 },
+};
+
+static struct otm3225a_spi_instruction display_off[] = {
+	{ DISPLAY_CTRL_1,	0x0131, 100 },
+	{ DISPLAY_CTRL_1,	0x0130, 100 },
+	{ DISPLAY_CTRL_1,	0x0100, 0 },
+	{ POWER_CTRL_1,		0x0280, 0 },
+	{ POWER_CTRL_3,		0x018B, 0 },
+};
+
+static struct otm3225a_spi_instruction display_on[] = {
+	{ POWER_CTRL_1,		0x1280, 0 },
+	{ DISPLAY_CTRL_1,	0x0101, 100 },
+	{ DISPLAY_CTRL_1,	0x0121, 0 },
+	{ DISPLAY_CTRL_1,	0x0123, 100 },
+	{ DISPLAY_CTRL_1,	0x0133, 10 },
+};
+
+static void otm3225a_write(struct spi_device *spi,
+			   struct otm3225a_spi_instruction *instruction,
+			   unsigned int count)
+{
+	unsigned char buf[3];
+
+	while (count--) {
+		/* address register using index register */
+		buf[0] = OTM3225A_INDEX_REG;
+		buf[1] = 0x00;
+		buf[2] = instruction->reg;
+		spi_write(spi, buf, 3);
+
+		/* write data to addressed register */
+		buf[0] = OTM3225A_DATA_REG;
+		buf[1] = (instruction->value >> 8) & 0xff;
+		buf[2] = instruction->value & 0xff;
+		spi_write(spi, buf, 3);
+
+		/* execute delay if any */
+		if (instruction->delay)
+			msleep(instruction->delay);
+		instruction++;
+	}
+}
+
+static int otm3225a_set_power(struct lcd_device *ld, int power)
+{
+	struct otm3225a_data *dd = lcd_get_data(ld);
+
+	if (power == dd->power)
+		return 0;
+
+	if (power > FB_BLANK_UNBLANK)
+		otm3225a_write(dd->spi, display_off, ARRAY_SIZE(display_off));
+	else
+		otm3225a_write(dd->spi, display_on, ARRAY_SIZE(display_on));
+	dd->power = power;
+
+	return 0;
+}
+
+static int otm3225a_get_power(struct lcd_device *ld)
+{
+	struct otm3225a_data *dd = lcd_get_data(ld);
+
+	return dd->power;
+}
+
+static struct lcd_ops otm3225a_ops = {
+	.set_power = otm3225a_set_power,
+	.get_power = otm3225a_get_power,
+};
+
+static int otm3225a_probe(struct spi_device *spi)
+{
+	struct otm3225a_data *dd;
+	struct lcd_device *ld;
+	struct device *dev = &spi->dev;
+
+	dd = devm_kzalloc(dev, sizeof(struct otm3225a_data), GFP_KERNEL);
+	if (dd == NULL)
+		return -ENOMEM;
+
+	ld = devm_lcd_device_register(dev, dev_name(dev), dev, dd,
+				      &otm3225a_ops);
+	if (IS_ERR(ld))
+		return PTR_ERR(ld);
+
+	dd->spi = spi;
+	dd->ld = ld;
+	dev_set_drvdata(dev, dd);
+
+	dev_info(dev, "Initializing and switching to RGB interface");
+	otm3225a_write(spi, display_init, ARRAY_SIZE(display_init));
+	otm3225a_write(spi, display_enable_rgb_interface,
+		       ARRAY_SIZE(display_enable_rgb_interface));
+	return 0;
+}
+
+static struct spi_driver otm3225a_driver = {
+	.driver = {
+		.name = "otm3225a",
+		.owner = THIS_MODULE,
+	},
+	.probe = otm3225a_probe,
+};
+
+module_spi_driver(otm3225a_driver);
+
+MODULE_AUTHOR("Felix Brack <[e-mail]>");
+MODULE_DESCRIPTION("OTM3225A TFT LCD driver");
+MODULE_VERSION("1.0.0");
+MODULE_LICENSE("GPL v2");