Re: [PATCH v4 3/7] drm/tinydrm: Add MIPI DBI support

[Daniel Vetter]

On Sat, Feb 11, 2017 at 07:48:54PM +0100, Noralf Trønnes wrote:
> +static int mipi_dbi_buf_copy(void *dst, struct drm_framebuffer *fb,
> +				struct drm_clip_rect *clip, bool swap)
> +{
> +	struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
> +	struct dma_buf_attachment *import_attach = cma_obj->base.import_attach;
> +	struct drm_format_name_buf format_name;
> +	void *src = cma_obj->vaddr;
> +	int ret = 0;
> +
> +	if (import_attach) {
> +		ret = dma_buf_begin_cpu_access(import_attach->dmabuf,
> +					       DMA_FROM_DEVICE);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	switch (fb->format->format) {
> +	case DRM_FORMAT_RGB565:
> +		if (swap)
> +			tinydrm_swab16(dst, src, fb, clip);
> +		else
> +			tinydrm_memcpy(dst, src, fb, clip);
> +		break;
> +	case DRM_FORMAT_XRGB8888:
> +		tinydrm_xrgb8888_to_rgb565(dst, src, fb, clip, swap);
> +		break;

Already mentioned in my other mail that this here is kinda not cool. At
least I think we'll digg ourselves into a big hole if we start to convert
xrgb8888 into whatever the device actually supports in drm drivers. This
works for devices behind a slow upload link (because the cpu is likely
much faster), but for anything else userspace really must support the
native pixel format. And rgb565 is a rather common format, there should be
no reason to duct-tape around it.

> +	default:
> +		dev_err_once(fb->dev->dev, "Format is not supported: %s\n",
> +			     drm_get_format_name(fb->format->format,
> +						 &format_name));
> +		return -EINVAL;
> +	}
> +
> +	if (import_attach)
> +		ret = dma_buf_end_cpu_access(import_attach->dmabuf,
> +					     DMA_FROM_DEVICE);
> +	return ret;
> +}
> +
> +static int mipi_dbi_fb_dirty(struct drm_framebuffer *fb,
> +			     struct drm_file *file_priv,
> +			     unsigned int flags, unsigned int color,
> +			     struct drm_clip_rect *clips,
> +			     unsigned int num_clips)
> +{
> +	struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
> +	struct tinydrm_device *tdev = fb->dev->dev_private;
> +	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
> +	bool swap = mipi->swap_bytes;
> +	struct drm_clip_rect clip;
> +	int ret = 0;
> +	bool full;
> +	void *tr;
> +
> +	mutex_lock(&tdev->dirty_lock);
> +
> +	if (!mipi->enabled)
> +		goto out_unlock;

Here's the real reason I replied: I think long term-ish we need to rework
what you use as the main upload function in tinydrm. I realize just using
fb->dirty is convenient, because simple_pipe->upload doesn't take a dirty
rectangle. But long term I think we need to fix that, because otherwise
we'll reinvent the same few lines of boilerplate (like here and in the
other tinydrm drivers you have queued).

Rough sketch of a plan:

- Add a struct drm_rect dirty_clip to drm_crtc_state. When duplicating the
  crtc state, clear that to the max values, x/y = 0 and w/h = MAX_INT, in
  __drm_atomic_helper_crtc_duplicate_state().

> +
> +	/* fbdev can flush even when we're not interested */
> +	if (tdev->pipe.plane.fb != fb)
> +		goto out_unlock;
> +
> +	full = tinydrm_merge_clips(&clip, clips, num_clips, flags,
> +				   fb->width, fb->height);

- Move tinydrm_merge_clips into drm_framebuffer.c, dropping the tinydrm_
  prefix ofc and using drm_fb_. drm_framebuffer.c makes sense since this
  is a function useful to implement the fb->dirty function.

- Create a new drm_fb_dirty function which does essentially what you do
  here, but generic. You can use e.g. drm_atomic_helper_update_plane as
  the template. But instead of doing a simple full-screen plane update,
  this new helper also sets crtc_state->dirty_clip to the right
  coordinates. And of course it needs to check whether the fb is actually
  active (and maybe where), so there's some book-keeping involved. There's
  also some good fun involved in scaling things appropriately. For that
  case we might simply give up and declare the entire area covered by the
  plane as dirty.

Tinydrm drivers (and really, anything using drm_simple_pipe) then just
implement the ->update hook, obeying the dirty_clip rectangle, and you can
remove tinydrm_display_pipe_update().

The upshot of all this is two-fold:

- You get rid of a tiny bit of book-keeping in each tinydrm driver (the
  merge_clips above, plus the "is this the current fb on our hw" check).

- There's lots more manual upload devices than just tinydrm, or
  drm_simple_pipe, this would benefit any atomic driver.

- Long-term we want to expose the dirty_clip as properties to userspace,
  since the compositor already computes this anyway for each atomic update
  (at least good compositors do this). Test-driving these new properties
  within the kernel would help in catching issues.

The only downside is that we won't have a clip rect list anymore, but no
one (except for vmwgfx) seems to use that anyway.
-Daniel

> +
> +	DRM_DEBUG("Flushing [FB:%d] x1=%u, x2=%u, y1=%u, y2=%u\n", fb->base.id,
> +		  clip.x1, clip.x2, clip.y1, clip.y2);
> +
> +	if (!mipi->dc || !full || swap ||
> +	    fb->format->format == DRM_FORMAT_XRGB8888) {
> +		tr = mipi->tx_buf;
> +		ret = mipi_dbi_buf_copy(mipi->tx_buf, fb, &clip, swap);
> +		if (ret)
> +			goto out_unlock;
> +	} else {
> +		tr = cma_obj->vaddr;
> +	}
> +
> +	mipi_dbi_command(mipi, MIPI_DCS_SET_COLUMN_ADDRESS,
> +			 (clip.x1 >> 8) & 0xFF, clip.x1 & 0xFF,
> +			 (clip.x2 >> 8) & 0xFF, (clip.x2 - 1) & 0xFF);
> +	mipi_dbi_command(mipi, MIPI_DCS_SET_PAGE_ADDRESS,
> +			 (clip.y1 >> 8) & 0xFF, clip.y1 & 0xFF,
> +			 (clip.y2 >> 8) & 0xFF, (clip.y2 - 1) & 0xFF);
> +
> +	ret = mipi_dbi_command_buf(mipi, MIPI_DCS_WRITE_MEMORY_START, tr,
> +				(clip.x2 - clip.x1) * (clip.y2 - clip.y1) * 2);
> +
> +out_unlock:
> +	mutex_unlock(&tdev->dirty_lock);
> +
> +	if (ret)
> +		dev_err_once(fb->dev->dev, "Failed to update display %d\n",
> +			     ret);
> +
> +	return ret;
> +}
> +
> +static const struct drm_framebuffer_funcs mipi_dbi_fb_funcs = {
> +	.destroy	= drm_fb_cma_destroy,
> +	.create_handle	= drm_fb_cma_create_handle,
> +	.dirty		= mipi_dbi_fb_dirty,
> +};
> +
> +/**
> + * mipi_dbi_pipe_enable - MIPI DBI pipe enable helper
> + * @pipe: Display pipe
> + * @crtc_state: CRTC state
> + *
> + * This function enables backlight. Drivers can use this as their
> + * &drm_simple_display_pipe_funcs->enable callback.
> + */
> +void mipi_dbi_pipe_enable(struct drm_simple_display_pipe *pipe,
> +			  struct drm_crtc_state *crtc_state)
> +{
> +	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
> +	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
> +	struct drm_framebuffer *fb = pipe->plane.fb;
> +
> +	DRM_DEBUG_KMS("\n");
> +
> +	mipi->enabled = true;
> +	if (fb)
> +		fb->funcs->dirty(fb, NULL, 0, 0, NULL, 0);
> +
> +	tinydrm_enable_backlight(mipi->backlight);
> +}
> +EXPORT_SYMBOL(mipi_dbi_pipe_enable);
> +
> +static void mipi_dbi_blank(struct mipi_dbi *mipi)
> +{
> +	struct drm_device *drm = mipi->tinydrm.drm;
> +	u16 height = drm->mode_config.min_height;
> +	u16 width = drm->mode_config.min_width;
> +	size_t len = width * height * 2;
> +
> +	memset(mipi->tx_buf, 0, len);
> +
> +	mipi_dbi_command(mipi, MIPI_DCS_SET_COLUMN_ADDRESS, 0, 0,
> +			 (width >> 8) & 0xFF, (width - 1) & 0xFF);
> +	mipi_dbi_command(mipi, MIPI_DCS_SET_PAGE_ADDRESS, 0, 0,
> +			 (height >> 8) & 0xFF, (height - 1) & 0xFF);
> +	mipi_dbi_command_buf(mipi, MIPI_DCS_WRITE_MEMORY_START,
> +			     (u8 *)mipi->tx_buf, len);
> +}
> +
> +/**
> + * mipi_dbi_pipe_disable - MIPI DBI pipe disable helper
> + * @pipe: Display pipe
> + *
> + * This function disables backlight if present or if not the
> + * display memory is blanked. Drivers can use this as their
> + * &drm_simple_display_pipe_funcs->disable callback.
> + */
> +void mipi_dbi_pipe_disable(struct drm_simple_display_pipe *pipe)
> +{
> +	struct tinydrm_device *tdev = pipe_to_tinydrm(pipe);
> +	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
> +
> +	DRM_DEBUG_KMS("\n");
> +
> +	mipi->enabled = false;
> +
> +	if (mipi->backlight)
> +		tinydrm_disable_backlight(mipi->backlight);
> +	else
> +		mipi_dbi_blank(mipi);
> +}
> +EXPORT_SYMBOL(mipi_dbi_pipe_disable);
> +
> +static const uint32_t mipi_dbi_formats[] = {
> +	DRM_FORMAT_RGB565,
> +	DRM_FORMAT_XRGB8888,
> +};
> +
> +/**
> + * mipi_dbi_init - MIPI DBI initialization
> + * @dev: Parent device
> + * @mipi: &mipi_dbi structure to initialize
> + * @pipe_funcs: Display pipe functions
> + * @driver: DRM driver
> + * @mode: Display mode
> + * @rotation: Initial rotation in degrees Counter Clock Wise
> + *
> + * This function initializes a &mipi_dbi structure and it's underlying
> + * @tinydrm_device. It also sets up the display pipeline.
> + *
> + * Supported formats: Native RGB565 and emulated XRGB8888.
> + *
> + * Objects created by this function will be automatically freed on driver
> + * detach (devres).
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */
> +int mipi_dbi_init(struct device *dev, struct mipi_dbi *mipi,
> +		  const struct drm_simple_display_pipe_funcs *pipe_funcs,
> +		  struct drm_driver *driver,
> +		  const struct drm_display_mode *mode, unsigned int rotation)
> +{
> +	size_t bufsize = mode->vdisplay * mode->hdisplay * sizeof(u16);
> +	struct tinydrm_device *tdev = &mipi->tinydrm;
> +	int ret;
> +
> +	if (!mipi->command)
> +		return -EINVAL;
> +
> +	mutex_init(&mipi->cmdlock);
> +
> +	mipi->tx_buf = devm_kmalloc(dev, bufsize, GFP_KERNEL);
> +	if (!mipi->tx_buf)
> +		return -ENOMEM;
> +
> +	ret = devm_tinydrm_init(dev, tdev, &mipi_dbi_fb_funcs, driver);
> +	if (ret)
> +		return ret;
> +
> +	/* TODO: Maybe add DRM_MODE_CONNECTOR_SPI */
> +	ret = tinydrm_display_pipe_init(tdev, pipe_funcs,
> +					DRM_MODE_CONNECTOR_VIRTUAL,
> +					mipi_dbi_formats,
> +					ARRAY_SIZE(mipi_dbi_formats), mode,
> +					rotation);
> +	if (ret)
> +		return ret;
> +
> +	tdev->drm->mode_config.preferred_depth = 16;
> +	mipi->rotation = rotation;
> +
> +	drm_mode_config_reset(tdev->drm);
> +
> +	DRM_DEBUG_KMS("preferred_depth=%u, rotation = %u\n",
> +		      tdev->drm->mode_config.preferred_depth, rotation);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(mipi_dbi_init);
> +
> +/**
> + * mipi_dbi_hw_reset - Hardware reset of controller
> + * @mipi: MIPI DBI structure
> + *
> + * Reset controller if the &mipi_dbi->reset gpio is set.
> + */
> +void mipi_dbi_hw_reset(struct mipi_dbi *mipi)
> +{
> +	if (!mipi->reset)
> +		return;
> +
> +	gpiod_set_value_cansleep(mipi->reset, 0);
> +	msleep(20);
> +	gpiod_set_value_cansleep(mipi->reset, 1);
> +	msleep(120);
> +}
> +EXPORT_SYMBOL(mipi_dbi_hw_reset);
> +
> +/**
> + * mipi_dbi_display_is_on - Check if display is on
> + * @mipi: 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 *mipi)
> +{
> +	u8 val;
> +
> +	if (mipi_dbi_command_read(mipi, MIPI_DCS_GET_POWER_MODE, &val))
> +		return false;
> +
> +	val &= ~DCS_POWER_MODE_RESERVED_MASK;
> +
> +	if (val != (DCS_POWER_MODE_DISPLAY |
> +	    DCS_POWER_MODE_DISPLAY_NORMAL_MODE | DCS_POWER_MODE_SLEEP_MODE))
> +		return false;
> +
> +	DRM_DEBUG_DRIVER("Display is ON\n");
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(mipi_dbi_display_is_on);
> +
> +#if IS_ENABLED(CONFIG_SPI)
> +
> +/*
> + * 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.
> + */
> +static 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);
> +}
> +
> +/*
> + * MIPI DBI Type C Option 1
> + *
> + * If the SPI controller doesn't have 9 bits per word support,
> + * use blocks of 9 bytes to send 8x 9-bit words using a 8-bit SPI transfer.
> + * Pad partial blocks with MIPI_DCS_NOP (zero).
> + * This is how the D/C bit (x) is added:
> + *     x7654321
> + *     0x765432
> + *     10x76543
> + *     210x7654
> + *     3210x765
> + *     43210x76
> + *     543210x7
> + *     6543210x
> + *     76543210
> + */
> +
> +static int mipi_dbi_spi1e_transfer(struct mipi_dbi *mipi, int dc,
> +				   const void *buf, size_t len,
> +				   unsigned int bpw)
> +{
> +	bool swap_bytes = (bpw == 16 && tinydrm_machine_little_endian());
> +	size_t chunk, max_chunk = mipi->tx_buf9_len;
> +	struct spi_device *spi = mipi->spi;
> +	struct spi_transfer tr = {
> +		.tx_buf = mipi->tx_buf9,
> +		.bits_per_word = 8,
> +	};
> +	struct spi_message m;
> +	const u8 *src = buf;
> +	int i, ret;
> +	u8 *dst;
> +
> +	if (drm_debug & DRM_UT_DRIVER)
> +		pr_debug("[drm:%s] dc=%d, max_chunk=%zu, transfers:\n",
> +			 __func__, dc, max_chunk);
> +
> +	tr.speed_hz = mipi_dbi_spi_cmd_max_speed(spi, len);
> +	spi_message_init_with_transfers(&m, &tr, 1);
> +
> +	if (!dc) {
> +		if (WARN_ON_ONCE(len != 1))
> +			return -EINVAL;
> +
> +		/* Command: pad no-op's (zeroes) at beginning of block */
> +		dst = mipi->tx_buf9;
> +		memset(dst, 0, 9);
> +		dst[8] = *src;
> +		tr.len = 9;
> +
> +		tinydrm_dbg_spi_message(spi, &m);
> +
> +		return spi_sync(spi, &m);
> +	}
> +
> +	/* max with room for adding one bit per byte */
> +	max_chunk = max_chunk / 9 * 8;
> +	/* but no bigger than len */
> +	max_chunk = min(max_chunk, len);
> +	/* 8 byte blocks */
> +	max_chunk = max_t(size_t, 8, max_chunk & ~0x7);
> +
> +	while (len) {
> +		size_t added = 0;
> +
> +		chunk = min(len, max_chunk);
> +		len -= chunk;
> +		dst = mipi->tx_buf9;
> +
> +		if (chunk < 8) {
> +			u8 val, carry = 0;
> +
> +			/* Data: pad no-op's (zeroes) at end of block */
> +			memset(dst, 0, 9);
> +
> +			if (swap_bytes) {
> +				for (i = 1; i < (chunk + 1); i++) {
> +					val = src[1];
> +					*dst++ = carry | BIT(8 - i) | (val >> i);
> +					carry = val << (8 - i);
> +					i++;
> +					val = src[0];
> +					*dst++ = carry | BIT(8 - i) | (val >> i);
> +					carry = val << (8 - i);
> +					src += 2;
> +				}
> +				*dst++ = carry;
> +			} else {
> +				for (i = 1; i < (chunk + 1); i++) {
> +					val = *src++;
> +					*dst++ = carry | BIT(8 - i) | (val >> i);
> +					carry = val << (8 - i);
> +				}
> +				*dst++ = carry;
> +			}
> +
> +			chunk = 8;
> +			added = 1;
> +		} else {
> +			for (i = 0; i < chunk; i += 8) {
> +				if (swap_bytes) {
> +					*dst++ =                 BIT(7) | (src[1] >> 1);
> +					*dst++ = (src[1] << 7) | BIT(6) | (src[0] >> 2);
> +					*dst++ = (src[0] << 6) | BIT(5) | (src[3] >> 3);
> +					*dst++ = (src[3] << 5) | BIT(4) | (src[2] >> 4);
> +					*dst++ = (src[2] << 4) | BIT(3) | (src[5] >> 5);
> +					*dst++ = (src[5] << 3) | BIT(2) | (src[4] >> 6);
> +					*dst++ = (src[4] << 2) | BIT(1) | (src[7] >> 7);
> +					*dst++ = (src[7] << 1) | BIT(0);
> +					*dst++ = src[6];
> +				} else {
> +					*dst++ =                 BIT(7) | (src[0] >> 1);
> +					*dst++ = (src[0] << 7) | BIT(6) | (src[1] >> 2);
> +					*dst++ = (src[1] << 6) | BIT(5) | (src[2] >> 3);
> +					*dst++ = (src[2] << 5) | BIT(4) | (src[3] >> 4);
> +					*dst++ = (src[3] << 4) | BIT(3) | (src[4] >> 5);
> +					*dst++ = (src[4] << 3) | BIT(2) | (src[5] >> 6);
> +					*dst++ = (src[5] << 2) | BIT(1) | (src[6] >> 7);
> +					*dst++ = (src[6] << 1) | BIT(0);
> +					*dst++ = src[7];
> +				}
> +
> +				src += 8;
> +				added++;
> +			}
> +		}
> +
> +		tr.len = chunk + added;
> +
> +		tinydrm_dbg_spi_message(spi, &m);
> +		ret = spi_sync(spi, &m);
> +		if (ret)
> +			return ret;
> +	};
> +
> +	return 0;
> +}
> +
> +static int mipi_dbi_spi1_transfer(struct mipi_dbi *mipi, int dc,
> +				  const void *buf, size_t len,
> +				  unsigned int bpw)
> +{
> +	struct spi_device *spi = mipi->spi;
> +	struct spi_transfer tr = {
> +		.bits_per_word = 9,
> +	};
> +	const u16 *src16 = buf;
> +	const u8 *src8 = buf;
> +	struct spi_message m;
> +	size_t max_chunk;
> +	u16 *dst16;
> +	int ret;
> +
> +	if (!tinydrm_spi_bpw_supported(spi, 9))
> +		return mipi_dbi_spi1e_transfer(mipi, dc, buf, len, bpw);
> +
> +	tr.speed_hz = mipi_dbi_spi_cmd_max_speed(spi, len);
> +	max_chunk = mipi->tx_buf9_len;
> +	dst16 = mipi->tx_buf9;
> +
> +	if (drm_debug & DRM_UT_DRIVER)
> +		pr_debug("[drm:%s] dc=%d, max_chunk=%zu, transfers:\n",
> +			 __func__, dc, max_chunk);
> +
> +	max_chunk = min(max_chunk / 2, len);
> +
> +	spi_message_init_with_transfers(&m, &tr, 1);
> +	tr.tx_buf = dst16;
> +
> +	while (len) {
> +		size_t chunk = min(len, max_chunk);
> +		unsigned int i;
> +
> +		if (bpw == 16 && tinydrm_machine_little_endian()) {
> +			for (i = 0; i < (chunk * 2); i += 2) {
> +				dst16[i]     = *src16 >> 8;
> +				dst16[i + 1] = *src16++ & 0xFF;
> +				if (dc) {
> +					dst16[i]     |= 0x0100;
> +					dst16[i + 1] |= 0x0100;
> +				}
> +			}
> +		} else {
> +			for (i = 0; i < chunk; i++) {
> +				dst16[i] = *src8++;
> +				if (dc)
> +					dst16[i] |= 0x0100;
> +			}
> +		}
> +
> +		tr.len = chunk;
> +		len -= chunk;
> +
> +		tinydrm_dbg_spi_message(spi, &m);
> +		ret = spi_sync(spi, &m);
> +		if (ret)
> +			return ret;
> +	};
> +
> +	return 0;
> +}
> +
> +static int mipi_dbi_typec1_command(struct mipi_dbi *mipi, u8 cmd,
> +				   u8 *parameters, size_t num)
> +{
> +	unsigned int bpw = (cmd == MIPI_DCS_WRITE_MEMORY_START) ? 16 : 8;
> +	int ret;
> +
> +	if (mipi_dbi_command_is_read(mipi, cmd))
> +		return -ENOTSUPP;
> +
> +	MIPI_DBI_DEBUG_COMMAND(cmd, parameters, num);
> +
> +	ret = mipi_dbi_spi1_transfer(mipi, 0, &cmd, 1, 8);
> +	if (ret || !num)
> +		return ret;
> +
> +	return mipi_dbi_spi1_transfer(mipi, 1, parameters, num, bpw);
> +}
> +
> +/* MIPI DBI Type C Option 3 */
> +
> +static int mipi_dbi_typec3_command_read(struct mipi_dbi *mipi, u8 cmd,
> +					u8 *data, size_t len)
> +{
> +	struct spi_device *spi = mipi->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_cansleep(mipi->dc, 0);
> +
> +	spi_message_init_with_transfers(&m, tr, ARRAY_SIZE(tr));
> +	ret = spi_sync(spi, &m);
> +	if (ret)
> +		goto err_free;
> +
> +	tinydrm_dbg_spi_message(spi, &m);
> +
> +	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] & BIT(7));
> +	}
> +
> +	MIPI_DBI_DEBUG_COMMAND(cmd, data, len);
> +
> +err_free:
> +	kfree(buf);
> +
> +	return ret;
> +}
> +
> +static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 cmd,
> +				   u8 *par, size_t num)
> +{
> +	struct spi_device *spi = mipi->spi;
> +	unsigned int bpw = 8;
> +	u32 speed_hz;
> +	int ret;
> +
> +	if (mipi_dbi_command_is_read(mipi, cmd))
> +		return mipi_dbi_typec3_command_read(mipi, cmd, par, num);
> +
> +	MIPI_DBI_DEBUG_COMMAND(cmd, par, num);
> +
> +	gpiod_set_value_cansleep(mipi->dc, 0);
> +	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
> +	ret = tinydrm_spi_transfer(spi, speed_hz, NULL, 8, &cmd, 1);
> +	if (ret || !num)
> +		return ret;
> +
> +	if (cmd == MIPI_DCS_WRITE_MEMORY_START && !mipi->swap_bytes)
> +		bpw = 16;
> +
> +	gpiod_set_value_cansleep(mipi->dc, 1);
> +	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
> +
> +	return tinydrm_spi_transfer(spi, speed_hz, NULL, bpw, par, num);
> +}
> +
> +/**
> + * mipi_dbi_spi_init - Initialize MIPI DBI SPI interfaced controller
> + * @spi: SPI device
> + * @dc: D/C gpio (optional)
> + * @mipi: &mipi_dbi structure to initialize
> + * @pipe_funcs: Display pipe functions
> + * @driver: DRM driver
> + * @mode: Display mode
> + * @rotation: Initial rotation in degrees Counter Clock Wise
> + *
> + * This function sets &mipi_dbi->command, enables &mipi->read_commands for the
> + * usual read commands and initializes @mipi using mipi_dbi_init().
> + *
> + * If @dc is set, a Type C Option 3 interface is assumed, if not
> + * Type C Option 1.
> + *
> + * 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 *mipi,
> +		      struct gpio_desc *dc,
> +		      const struct drm_simple_display_pipe_funcs *pipe_funcs,
> +		      struct drm_driver *driver,
> +		      const struct drm_display_mode *mode,
> +		      unsigned int rotation)
> +{
> +	size_t tx_size = tinydrm_spi_max_transfer_size(spi, 0);
> +	struct device *dev = &spi->dev;
> +	int ret;
> +
> +	if (tx_size < 16) {
> +		DRM_ERROR("SPI transmit buffer too small: %zu\n", tx_size);
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * Even though it's not the SPI device that does DMA (the master does),
> +	 * the dma mask is necessary for the dma_alloc_wc() in
> +	 * drm_gem_cma_create(). The dma_addr returned will be a physical
> +	 * adddress which might be different from the bus address, but this is
> +	 * not a problem since the address will not be used.
> +	 * The virtual address is used in the transfer and the SPI core
> +	 * re-maps it on the SPI master device using the DMA streaming API
> +	 * (spi_map_buf()).
> +	 */
> +	if (!dev->coherent_dma_mask) {
> +		ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
> +		if (ret) {
> +			dev_warn(dev, "Failed to set dma mask %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	mipi->spi = spi;
> +	mipi->read_commands = mipi_dbi_dcs_read_commands;
> +
> +	if (dc) {
> +		mipi->command = mipi_dbi_typec3_command;
> +		mipi->dc = dc;
> +		if (tinydrm_machine_little_endian() &&
> +		    !tinydrm_spi_bpw_supported(spi, 16))
> +			mipi->swap_bytes = true;
> +	} else {
> +		mipi->command = mipi_dbi_typec1_command;
> +		mipi->tx_buf9_len = tx_size;
> +		mipi->tx_buf9 = devm_kmalloc(dev, tx_size, GFP_KERNEL);
> +		if (!mipi->tx_buf9)
> +			return -ENOMEM;
> +	}
> +
> +	return mipi_dbi_init(dev, mipi, pipe_funcs, driver, mode, rotation);
> +}
> +EXPORT_SYMBOL(mipi_dbi_spi_init);
> +
> +#endif /* CONFIG_SPI */
> +
> +#ifdef CONFIG_DEBUG_FS
> +
> +static ssize_t mipi_dbi_debugfs_command_write(struct file *file,
> +					      const char __user *ubuf,
> +					      size_t count, loff_t *ppos)
> +{
> +	struct seq_file *m = file->private_data;
> +	struct mipi_dbi *mipi = m->private;
> +	u8 val, cmd, parameters[64];
> +	char *buf, *pos, *token;
> +	unsigned int i;
> +	int ret;
> +
> +	buf = memdup_user_nul(ubuf, count);
> +	if (IS_ERR(buf))
> +		return PTR_ERR(buf);
> +
> +	/* strip trailing whitespace */
> +	for (i = count - 1; i > 0; i--)
> +		if (isspace(buf[i]))
> +			buf[i] = '\0';
> +		else
> +			break;
> +	i = 0;
> +	pos = buf;
> +	while (pos) {
> +		token = strsep(&pos, " ");
> +		if (!token) {
> +			ret = -EINVAL;
> +			goto err_free;
> +		}
> +
> +		ret = kstrtou8(token, 16, &val);
> +		if (ret < 0)
> +			goto err_free;
> +
> +		if (token == buf)
> +			cmd = val;
> +		else
> +			parameters[i++] = val;
> +
> +		if (i == 64) {
> +			ret = -E2BIG;
> +			goto err_free;
> +		}
> +	}
> +
> +	ret = mipi_dbi_command_buf(mipi, cmd, parameters, i);
> +
> +err_free:
> +	kfree(buf);
> +
> +	return ret < 0 ? ret : count;
> +}
> +
> +static int mipi_dbi_debugfs_command_show(struct seq_file *m, void *unused)
> +{
> +	struct mipi_dbi *mipi = m->private;
> +	u8 cmd, val[4];
> +	size_t len, i;
> +	int ret;
> +
> +	for (cmd = 0; cmd < 255; cmd++) {
> +		if (!mipi_dbi_command_is_read(mipi, cmd))
> +			continue;
> +
> +		switch (cmd) {
> +		case MIPI_DCS_READ_MEMORY_START:
> +		case MIPI_DCS_READ_MEMORY_CONTINUE:
> +			len = 2;
> +			break;
> +		case MIPI_DCS_GET_DISPLAY_ID:
> +			len = 3;
> +			break;
> +		case MIPI_DCS_GET_DISPLAY_STATUS:
> +			len = 4;
> +			break;
> +		default:
> +			len = 1;
> +			break;
> +		}
> +
> +		seq_printf(m, "%02x: ", cmd);
> +		ret = mipi_dbi_command_buf(mipi, cmd, val, len);
> +		if (ret) {
> +			seq_puts(m, "XX\n");
> +			continue;
> +		}
> +
> +		for (i = 0; i < len; i++)
> +			seq_printf(m, "%02x", val[i]);
> +		seq_puts(m, "\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static int mipi_dbi_debugfs_command_open(struct inode *inode,
> +					 struct file *file)
> +{
> +	return single_open(file, mipi_dbi_debugfs_command_show,
> +			   inode->i_private);
> +}
> +
> +static const struct file_operations mipi_dbi_debugfs_command_fops = {
> +	.owner = THIS_MODULE,
> +	.open = mipi_dbi_debugfs_command_open,
> +	.read = seq_read,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +	.write = mipi_dbi_debugfs_command_write,
> +};
> +
> +static const struct drm_info_list mipi_dbi_debugfs_list[] = {
> +	{ "fb",   drm_fb_cma_debugfs_show, 0 },
> +};
> +
> +/**
> + * mipi_dbi_debugfs_init - Create debugfs entries
> + * @minor: DRM minor
> + *
> + * This function creates a 'command' debugfs file for sending commands to the
> + * controller or getting the read command values.
> + * Drivers can use this as their &drm_driver->debugfs_init callback.
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */
> +int mipi_dbi_debugfs_init(struct drm_minor *minor)
> +{
> +	struct tinydrm_device *tdev = minor->dev->dev_private;
> +	struct mipi_dbi *mipi = mipi_dbi_from_tinydrm(tdev);
> +	umode_t mode = S_IFREG | S_IWUSR;
> +
> +	if (mipi->read_commands)
> +		mode |= S_IRUGO;
> +	debugfs_create_file("command", mode, minor->debugfs_root, mipi,
> +			    &mipi_dbi_debugfs_command_fops);
> +
> +	return drm_debugfs_create_files(mipi_dbi_debugfs_list,
> +					ARRAY_SIZE(mipi_dbi_debugfs_list),
> +					minor->debugfs_root, minor);
> +}
> +EXPORT_SYMBOL(mipi_dbi_debugfs_init);
> +
> +#endif
> +
> +MODULE_LICENSE("GPL");
> diff --git a/include/drm/tinydrm/mipi-dbi.h b/include/drm/tinydrm/mipi-dbi.h
> new file mode 100644
> index 0000000..d137b16
> --- /dev/null
> +++ b/include/drm/tinydrm/mipi-dbi.h
> @@ -0,0 +1,107 @@
> +/*
> + * MIPI Display Bus Interface (DBI) LCD controller support
> + *
> + * Copyright 2016 Noralf Trønnes
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#ifndef __LINUX_MIPI_DBI_H
> +#define __LINUX_MIPI_DBI_H
> +
> +#include <drm/tinydrm/tinydrm.h>
> +
> +struct spi_device;
> +struct gpio_desc;
> +struct regulator;
> +
> +/**
> + * struct mipi_dbi - MIPI DBI controller
> + * @tinydrm: tinydrm base
> + * @spi: SPI device
> + * @enabled: Pipeline is enabled
> + * @cmdlock: Command lock
> + * @command: Bus specific callback executing commands.
> + * @read_commands: Array of read commands terminated by a zero entry.
> + *                 Reading is disabled if this is NULL.
> + * @dc: Optional D/C gpio.
> + * @tx_buf: Buffer used for transfer (copy clip rect area)
> + * @tx_buf9: Buffer used for Option 1 9-bit conversion
> + * @tx_buf9_len: Size of tx_buf9.
> + * @swap_bytes: Swap bytes in buffer before transfer
> + * @reset: Optional reset gpio
> + * @rotation: initial rotation in degrees Counter Clock Wise
> + * @backlight: backlight device (optional)
> + * @regulator: power regulator (optional)
> + */
> +struct mipi_dbi {
> +	struct tinydrm_device tinydrm;
> +	struct spi_device *spi;
> +	bool enabled;
> +	struct mutex cmdlock;
> +	int (*command)(struct mipi_dbi *mipi, u8 cmd, u8 *param, size_t num);
> +	const u8 *read_commands;
> +	struct gpio_desc *dc;
> +	u16 *tx_buf;
> +	void *tx_buf9;
> +	size_t tx_buf9_len;
> +	bool swap_bytes;
> +	struct gpio_desc *reset;
> +	unsigned int rotation;
> +	struct backlight_device *backlight;
> +	struct regulator *regulator;
> +};
> +
> +static inline struct mipi_dbi *
> +mipi_dbi_from_tinydrm(struct tinydrm_device *tdev)
> +{
> +	return container_of(tdev, struct mipi_dbi, tinydrm);
> +}
> +
> +int mipi_dbi_spi_init(struct spi_device *spi, struct mipi_dbi *mipi,
> +		      struct gpio_desc *dc,
> +		      const struct drm_simple_display_pipe_funcs *pipe_funcs,
> +		      struct drm_driver *driver,
> +		      const struct drm_display_mode *mode,
> +		      unsigned int rotation);
> +int mipi_dbi_init(struct device *dev, struct mipi_dbi *mipi,
> +		  const struct drm_simple_display_pipe_funcs *pipe_funcs,
> +		  struct drm_driver *driver,
> +		  const struct drm_display_mode *mode, unsigned int rotation);
> +void mipi_dbi_pipe_enable(struct drm_simple_display_pipe *pipe,
> +			  struct drm_crtc_state *crtc_state);
> +void mipi_dbi_pipe_disable(struct drm_simple_display_pipe *pipe);
> +void mipi_dbi_hw_reset(struct mipi_dbi *mipi);
> +bool mipi_dbi_display_is_on(struct mipi_dbi *mipi);
> +
> +int mipi_dbi_command_read(struct mipi_dbi *mipi, u8 cmd, u8 *val);
> +int mipi_dbi_command_buf(struct mipi_dbi *mipi, u8 cmd, u8 *data, size_t len);
> +
> +/**
> + * mipi_dbi_command - MIPI DCS command with optional parameter(s)
> + * @mipi: MIPI structure
> + * @cmd: Command
> + * @seq...: Optional parameter(s)
> + *
> + * Send MIPI DCS command to the controller. Use mipi_dbi_command_read() for
> + * get/read.
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */
> +#define mipi_dbi_command(mipi, cmd, seq...) \
> +({ \
> +	u8 d[] = { seq }; \
> +	mipi_dbi_command_buf(mipi, cmd, d, ARRAY_SIZE(d)); \
> +})
> +
> +#ifdef CONFIG_DEBUG_FS
> +int mipi_dbi_debugfs_init(struct drm_minor *minor);
> +#else
> +#define mipi_dbi_debugfs_init		NULL
> +#endif
> +
> +#endif /* __LINUX_MIPI_DBI_H */
> --
> 2.10.2
> 
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> dri-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch