Re: [PATCH 3/4] video: add MIPI DBI Type C Option 3 support

[Thorsten Scherer <t.scherer@eckelmann.de>]

Hi Ahmad,

uups.  I did not see v3 of this patch. Sorry for the noise.

On Wed, Feb 02, 2022 at 10:55:53AM +0100, Ahmad Fatoum wrote:
> 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>
> ---
>  commands/Kconfig         |  23 ++
>  commands/Makefile        |   1 +
>  drivers/video/Kconfig    |   3 +
>  drivers/video/Makefile   |   1 +
>  drivers/video/mipi_dbi.c | 467 +++++++++++++++++++++++++++++++++++++++
>  include/spi/spi.h        |  20 ++
>  6 files changed, 515 insertions(+)
>  create mode 100644 drivers/video/mipi_dbi.c
> 
> diff --git a/commands/Kconfig b/commands/Kconfig
> index ba8ca5cdebce..af60f7be1587 100644
> --- a/commands/Kconfig
> +++ b/commands/Kconfig
> @@ -1969,6 +1969,29 @@ config CMD_SPI
>  		  -w BIT	bits per word (default 8)
>  		  -v		verbose
>  
> +config CMD_MIPI_DBI
> +	bool
> +	depends on DRIVER_VIDEO_MIPI_DBI && SPI
> +	select PRINTF_HEXSTR
> +	prompt "mipi_dbi command"
> +	help
> +	  write/read from MIPI DBI SPI device
> +
> +	  Usage: mipi_dbi [-wld] [REG] [DATA...]
> +
> +	  Options:
> +		  -l		list all MIPI DBI devices
> +		  -d DEVICE	select specific device (default is first registered)
> +		  -w		issue write command
> +
> +BAREBOX_CMD_START(mipi_dbi)
> +	.cmd		= do_mipi_dbi,
> +	BAREBOX_CMD_DESC("write/read from MIPI DBI SPI device")
> +	BAREBOX_CMD_OPTS("[-wld] [REG] [DATA...]")
> +	BAREBOX_CMD_GROUP(CMD_GRP_HWMANIP)
> +	BAREBOX_CMD_HELP(cmd_mipi_dbi_help)
> +BAREBOX_CMD_END
> +
>  config CMD_LED_TRIGGER
>  	bool
>  	depends on LED_TRIGGERS
> diff --git a/commands/Makefile b/commands/Makefile
> index db78d0b877f6..fffb6d979e82 100644
> --- a/commands/Makefile
> +++ b/commands/Makefile
> @@ -67,6 +67,7 @@ obj-$(CONFIG_CMD_GPIO)		+= gpio.o
>  obj-$(CONFIG_CMD_UNCOMPRESS)	+= uncompress.o
>  obj-$(CONFIG_CMD_I2C)		+= i2c.o
>  obj-$(CONFIG_CMD_SPI)		+= spi.o
> +obj-$(CONFIG_CMD_MIPI_DBI)	+= mipi_dbi.o
>  obj-$(CONFIG_CMD_UBI)		+= ubi.o
>  obj-$(CONFIG_CMD_UBIFORMAT)	+= ubiformat.o
>  obj-$(CONFIG_CMD_MENU)		+= menu.o
> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
> index 1b8672fdea82..70d1d809536b 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 7f4429278987..a7b70d82072a 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 000000000000..48b1110f72ab
> --- /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");
> diff --git a/include/spi/spi.h b/include/spi/spi.h
> index c5ad6bd39ff9..d133e0e21265 100644
> --- a/include/spi/spi.h
> +++ b/include/spi/spi.h
> @@ -409,6 +409,26 @@ spi_message_add_tail(struct spi_transfer *t, struct spi_message *m)
>  	list_add_tail(&t->transfer_list, &m->transfers);
>  }
>  
> +/**
> + * spi_message_init_with_transfers - Initialize spi_message and append transfers
> + * @m: spi_message to be initialized
> + * @xfers: An array of spi transfers
> + * @num_xfers: Number of items in the xfer array
> + *
> + * This function initializes the given spi_message and adds each spi_transfer in
> + * the given array to the message.
> + */
> +static inline void
> +spi_message_init_with_transfers(struct spi_message *m,
> +struct spi_transfer *xfers, unsigned int num_xfers)
> +{
> +	unsigned int i;
> +
> +	spi_message_init(m);
> +	for (i = 0; i < num_xfers; ++i)
> +		spi_message_add_tail(&xfers[i], m);
> +}
> +
>  static inline void
>  spi_transfer_del(struct spi_transfer *t)
>  {
> -- 
> 2.30.2
> 
> 
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Best regards
Thorsten

--
Thorsten Scherer | Eckelmann AG | www.eckelmann.de |

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