video: add MIPI DBI Type C Option 3 support

Import the Linux v5.15 state of the driver to allow easy porting of
MIPI-DBI displays like the Ilitek 9431 added in a follow-up commit.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.barebox.org/20220202223023.341817-4-a.fatoum@pengutronix.de
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 471 insertions, 0 deletions

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 1b8672fdea..70d1d80953 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -129,6 +129,9 @@ config DRIVER_VIDEO_EDID
 	  This enabled support for reading and parsing EDID data from an attached
 	  monitor.
 
+config DRIVER_VIDEO_MIPI_DBI
+	bool
+
 config DRIVER_VIDEO_BACKLIGHT
 	bool "Add backlight support"
 	help
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 7f44292789..a7b70d8207 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_VIDEO_VPL) += vpl.o
 obj-$(CONFIG_DRIVER_VIDEO_MTL017) += mtl017.o
 obj-$(CONFIG_DRIVER_VIDEO_TC358767) += tc358767.o
 obj-$(CONFIG_DRIVER_VIDEO_SIMPLE_PANEL) += simple-panel.o
+obj-$(CONFIG_DRIVER_VIDEO_MIPI_DBI) += mipi_dbi.o
 
 obj-$(CONFIG_DRIVER_VIDEO_ATMEL) += atmel_lcdfb.o atmel_lcdfb_core.o
 obj-$(CONFIG_DRIVER_VIDEO_ATMEL_HLCD) += atmel_hlcdfb.o atmel_lcdfb_core.o
diff --git a/drivers/video/mipi_dbi.c b/drivers/video/mipi_dbi.c
new file mode 100644
index 0000000000..48b1110f72
--- /dev/null
+++ b/drivers/video/mipi_dbi.c
@@ -0,0 +1,467 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * MIPI Display Bus Interface (DBI) LCD controller support
+ *
+ * Copyright 2016 Noralf Trønnes
+ */
+
+#define pr_fmt(fmt) "mipi-dbi: " fmt
+
+#include <common.h>
+#include <linux/kernel.h>
+#include <linux/sizes.h>
+#include <gpiod.h>
+#include <regulator.h>
+#include <spi/spi.h>
+#include <video/mipi_dbi.h>
+
+#include <video/vpl.h>
+#include <video/mipi_display.h>
+#include <video/fourcc.h>
+
+#define MIPI_DBI_MAX_SPI_READ_SPEED 2000000 /* 2MHz */
+
+#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))
+
+LIST_HEAD(mipi_dbi_list);
+EXPORT_SYMBOL(mipi_dbi_list);
+
+/**
+ * DOC: overview
+ *
+ * This library provides helpers for MIPI Display Bus Interface (DBI)
+ * compatible display controllers.
+ *
+ * Many controllers for tiny lcd displays are MIPI compliant and can use this
+ * library. If a controller uses registers 0x2A and 0x2B to set the area to
+ * update and uses register 0x2C to write to frame memory, it is most likely
+ * MIPI compliant.
+ *
+ * Only MIPI Type 1 displays are supported since a full frame memory is needed.
+ *
+ * There are 3 MIPI DBI implementation types:
+ *
+ * A. Motorola 6800 type parallel bus
+ *
+ * B. Intel 8080 type parallel bus
+ *
+ * C. SPI type with 3 options:
+ *
+ *    1. 9-bit with the Data/Command signal as the ninth bit
+ *    2. Same as above except it's sent as 16 bits
+ *    3. 8-bit with the Data/Command signal as a separate D/CX pin
+ *
+ * Currently barebox mipi_dbi only supports Type C option 3 with
+ * mipi_dbi_spi_init().
+ */
+
+#define MIPI_DBI_DEBUG_COMMAND(cmd, data, len) \
+({ \
+	if (!len) \
+		pr_debug("cmd=%02x\n", cmd); \
+	else if (len <= 32) \
+		pr_debug("cmd=%02x, par=%*ph\n", cmd, (int)len, data);\
+	else \
+		pr_debug("cmd=%02x, len=%zu\n", cmd, len); \
+})
+
+static const u8 mipi_dbi_dcs_read_commands[] = {
+	MIPI_DCS_GET_DISPLAY_ID,
+	MIPI_DCS_GET_RED_CHANNEL,
+	MIPI_DCS_GET_GREEN_CHANNEL,
+	MIPI_DCS_GET_BLUE_CHANNEL,
+	MIPI_DCS_GET_DISPLAY_STATUS,
+	MIPI_DCS_GET_POWER_MODE,
+	MIPI_DCS_GET_ADDRESS_MODE,
+	MIPI_DCS_GET_PIXEL_FORMAT,
+	MIPI_DCS_GET_DISPLAY_MODE,
+	MIPI_DCS_GET_SIGNAL_MODE,
+	MIPI_DCS_GET_DIAGNOSTIC_RESULT,
+	MIPI_DCS_READ_MEMORY_START,
+	MIPI_DCS_READ_MEMORY_CONTINUE,
+	MIPI_DCS_GET_SCANLINE,
+	MIPI_DCS_GET_DISPLAY_BRIGHTNESS,
+	MIPI_DCS_GET_CONTROL_DISPLAY,
+	MIPI_DCS_GET_POWER_SAVE,
+	MIPI_DCS_GET_CABC_MIN_BRIGHTNESS,
+	MIPI_DCS_READ_DDB_START,
+	MIPI_DCS_READ_DDB_CONTINUE,
+	0, /* sentinel */
+};
+
+bool mipi_dbi_command_is_read(struct mipi_dbi *dbi, u8 cmd)
+{
+	unsigned int i;
+
+	if (!dbi->read_commands)
+		return false;
+
+	for (i = 0; i < 0xff; i++) {
+		if (!dbi->read_commands[i])
+			return false;
+		if (cmd == dbi->read_commands[i])
+			return true;
+	}
+
+	return false;
+}
+
+int mipi_dbi_command_read_len(int cmd)
+{
+	switch (cmd) {
+	case MIPI_DCS_READ_MEMORY_START:
+	case MIPI_DCS_READ_MEMORY_CONTINUE:
+		return 2;
+	case MIPI_DCS_GET_DISPLAY_ID:
+		return 3;
+	case MIPI_DCS_GET_DISPLAY_STATUS:
+		return 4;
+	default:
+		return 1;
+	}
+}
+
+/**
+ * mipi_dbi_command_read - MIPI DCS read command
+ * @dbi: MIPI DBI structure
+ * @cmd: Command
+ * @val: Value read
+ *
+ * Send MIPI DCS read command to the controller.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int mipi_dbi_command_read(struct mipi_dbi *dbi, u8 cmd, u8 *val)
+{
+	if (!dbi->read_commands)
+		return -EACCES;
+
+	if (!mipi_dbi_command_is_read(dbi, cmd))
+		return -EINVAL;
+
+	return mipi_dbi_command_buf(dbi, cmd, val, 1);
+}
+EXPORT_SYMBOL(mipi_dbi_command_read);
+
+/**
+ * mipi_dbi_command_buf - MIPI DCS command with parameter(s) in an array
+ * @dbi: MIPI DBI structure
+ * @cmd: Command
+ * @data: Parameter buffer
+ * @len: Buffer length
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int mipi_dbi_command_buf(struct mipi_dbi *dbi, u8 cmd, u8 *data, size_t len)
+{
+	u8 *cmdbuf;
+	int ret;
+
+	/* SPI requires dma-safe buffers */
+	cmdbuf = kmemdup(&cmd, 1, GFP_KERNEL);
+	if (!cmdbuf)
+		return -ENOMEM;
+
+	ret = dbi->command(dbi, cmdbuf, data, len);
+
+	kfree(cmdbuf);
+
+	return ret;
+}
+EXPORT_SYMBOL(mipi_dbi_command_buf);
+
+/* This should only be used by mipi_dbi_command() */
+int mipi_dbi_command_stackbuf(struct mipi_dbi *dbi, u8 cmd, const u8 *data,
+			      size_t len)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kmemdup(data, len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = mipi_dbi_command_buf(dbi, cmd, buf, len);
+
+	kfree(buf);
+
+	return ret;
+}
+EXPORT_SYMBOL(mipi_dbi_command_stackbuf);
+
+/**
+ * mipi_dbi_hw_reset - Hardware reset of controller
+ * @dbi: MIPI DBI structure
+ *
+ * Reset controller if the &mipi_dbi->reset gpio is set.
+ */
+void mipi_dbi_hw_reset(struct mipi_dbi *dbi)
+{
+	if (!gpio_is_valid(dbi->reset))
+		return;
+
+	gpiod_set_value(dbi->reset, 0);
+	udelay(20);
+	gpiod_set_value(dbi->reset, 1);
+	mdelay(120);
+}
+EXPORT_SYMBOL(mipi_dbi_hw_reset);
+
+/**
+ * mipi_dbi_display_is_on - Check if display is on
+ * @dbi: MIPI DBI structure
+ *
+ * This function checks the Power Mode register (if readable) to see if
+ * display output is turned on. This can be used to see if the bootloader
+ * has already turned on the display avoiding flicker when the pipeline is
+ * enabled.
+ *
+ * Returns:
+ * true if the display can be verified to be on, false otherwise.
+ */
+bool mipi_dbi_display_is_on(struct mipi_dbi *dbi)
+{
+	u8 val;
+
+	if (mipi_dbi_command_read(dbi, MIPI_DCS_GET_POWER_MODE, &val))
+		return false;
+
+	val &= ~DCS_POWER_MODE_RESERVED_MASK;
+
+	/* The poweron/reset value is 08h DCS_POWER_MODE_DISPLAY_NORMAL_MODE */
+	if (val != (DCS_POWER_MODE_DISPLAY |
+	    DCS_POWER_MODE_DISPLAY_NORMAL_MODE | DCS_POWER_MODE_SLEEP_MODE))
+		return false;
+
+	pr_debug("Display is ON\n");
+
+	return true;
+}
+EXPORT_SYMBOL(mipi_dbi_display_is_on);
+
+#if IS_ENABLED(CONFIG_SPI)
+
+/**
+ * mipi_dbi_spi_cmd_max_speed - get the maximum SPI bus speed
+ * @spi: SPI device
+ * @len: The transfer buffer length.
+ *
+ * Many controllers have a max speed of 10MHz, but can be pushed way beyond
+ * that. Increase reliability by running pixel data at max speed and the rest
+ * at 10MHz, preventing transfer glitches from messing up the init settings.
+ */
+u32 mipi_dbi_spi_cmd_max_speed(struct spi_device *spi, size_t len)
+{
+	if (len > 64)
+		return 0; /* use default */
+
+	return min_t(u32, 10000000, spi->max_speed_hz);
+}
+EXPORT_SYMBOL(mipi_dbi_spi_cmd_max_speed);
+
+static bool mipi_dbi_machine_little_endian(void)
+{
+#if defined(__LITTLE_ENDIAN)
+	return true;
+#else
+	return false;
+#endif
+}
+
+/* MIPI DBI Type C Option 3 */
+
+static int mipi_dbi_typec3_command_read(struct mipi_dbi *dbi, u8 *cmd,
+					u8 *data, size_t len)
+{
+	struct spi_device *spi = dbi->spi;
+	u32 speed_hz = min_t(u32, MIPI_DBI_MAX_SPI_READ_SPEED,
+			     spi->max_speed_hz / 2);
+	struct spi_transfer tr[2] = {
+		{
+			.speed_hz = speed_hz,
+			.tx_buf = cmd,
+			.len = 1,
+		}, {
+			.speed_hz = speed_hz,
+			.len = len,
+		},
+	};
+	struct spi_message m;
+	u8 *buf;
+	int ret;
+
+	if (!len)
+		return -EINVAL;
+
+	/*
+	 * Support non-standard 24-bit and 32-bit Nokia read commands which
+	 * start with a dummy clock, so we need to read an extra byte.
+	 */
+	if (*cmd == MIPI_DCS_GET_DISPLAY_ID ||
+	    *cmd == MIPI_DCS_GET_DISPLAY_STATUS) {
+		if (!(len == 3 || len == 4))
+			return -EINVAL;
+
+		tr[1].len = len + 1;
+	}
+
+	buf = kmalloc(tr[1].len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	tr[1].rx_buf = buf;
+	gpiod_set_value(dbi->dc, 0);
+
+	spi_message_init_with_transfers(&m, tr, ARRAY_SIZE(tr));
+	ret = spi_sync(spi, &m);
+	if (ret)
+		goto err_free;
+
+	if (tr[1].len == len) {
+		memcpy(data, buf, len);
+	} else {
+		unsigned int i;
+
+		for (i = 0; i < len; i++)
+			data[i] = (buf[i] << 1) | (buf[i + 1] >> 7);
+	}
+
+	MIPI_DBI_DEBUG_COMMAND(*cmd, data, len);
+
+err_free:
+	kfree(buf);
+
+	return ret;
+}
+
+static int mipi_dbi_typec3_command(struct mipi_dbi *dbi, u8 *cmd,
+				   u8 *par, size_t num)
+{
+	struct spi_device *spi = dbi->spi;
+	unsigned int bpw = 8;
+	u32 speed_hz;
+	int ret;
+
+	if (mipi_dbi_command_is_read(dbi, *cmd))
+		return mipi_dbi_typec3_command_read(dbi, cmd, par, num);
+
+	MIPI_DBI_DEBUG_COMMAND(*cmd, par, num);
+
+	gpiod_set_value(dbi->dc, 0);
+	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
+	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
+	if (ret || !num)
+		return ret;
+
+	if (*cmd == MIPI_DCS_WRITE_MEMORY_START && !dbi->swap_bytes)
+		bpw = 16;
+
+	gpiod_set_value(dbi->dc, 1);
+	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
+
+	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
+}
+
+/**
+ * mipi_dbi_spi_init - Initialize MIPI DBI SPI interface
+ * @spi: SPI device
+ * @dbi: MIPI DBI structure to initialize
+ * @dc: D/C gpio
+ *
+ * This function sets &mipi_dbi->command, enables &mipi_dbi->read_commands for the
+ * usual read commands. It should be followed by a call to mipi_dbi_dev_init() or
+ * a driver-specific init.
+ *
+ * Type C Option 3 interface is assumed, Type C Option 1 is not yet supported,
+ * because barebox has no generic way yet to require a 9-bit SPI transfer
+ *
+ * If the SPI master driver doesn't support the necessary bits per word,
+ * the following transformation is used:
+ *
+ * - 9-bit: reorder buffer as 9x 8-bit words, padded with no-op command.
+ * - 16-bit: if big endian send as 8-bit, if little endian swap bytes
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int mipi_dbi_spi_init(struct spi_device *spi, struct mipi_dbi *dbi,
+		      int dc)
+{
+	struct device_d *dev = &spi->dev;
+
+	dbi->spi = spi;
+	dbi->read_commands = mipi_dbi_dcs_read_commands;
+
+	if (!gpio_is_valid(dc)) {
+		dev_dbg(dev, "MIPI DBI Type-C 1 unsupported\n");
+		return -ENOSYS;
+	}
+
+	dbi->command = mipi_dbi_typec3_command;
+	dbi->dc = dc;
+	// TODO: can we just force 16 bit?
+	if (mipi_dbi_machine_little_endian() && spi->bits_per_word != 16)
+		dbi->swap_bytes = true;
+
+	dev_dbg(dev, "SPI speed: %uMHz\n", spi->max_speed_hz / 1000000);
+
+	list_add(&dbi->list, &mipi_dbi_list);
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dbi_spi_init);
+
+/**
+ * mipi_dbi_spi_transfer - SPI transfer helper
+ * @spi: SPI device
+ * @speed_hz: Override speed (optional)
+ * @bpw: Bits per word
+ * @buf: Buffer to transfer
+ * @len: Buffer length
+ *
+ * This SPI transfer helper breaks up the transfer of @buf into chunks which
+ * the SPI controller driver can handle.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
+			  u8 bpw, const void *buf, size_t len)
+{
+	size_t max_chunk = spi_max_transfer_size(spi);
+	struct spi_transfer tr = {
+		.bits_per_word = bpw,
+		.speed_hz = speed_hz,
+	};
+	struct spi_message m;
+	size_t chunk;
+	int ret;
+
+	spi_message_init_with_transfers(&m, &tr, 1);
+
+	while (len) {
+		chunk = min(len, max_chunk);
+
+		tr.tx_buf = buf;
+		tr.len = chunk;
+		buf += chunk;
+		len -= chunk;
+
+		ret = spi_sync(spi, &m);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dbi_spi_transfer);
+
+#endif /* CONFIG_SPI */
+
+MODULE_LICENSE("GPL");