[5/9] drm/tinydrm: Add helper functions

Commit Message

Noralf Trønnes Jan. 22, 2017, 6:11 p.m. UTC

Add common functionality needed by many tinydrm drivers.

Signed-off-by: Noralf Trønnes <[e-mail]>
---
 Documentation/gpu/drm-kms-helpers.rst          |   6 +
 drivers/gpu/drm/tinydrm/core/Makefile          |   2 +-
 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 490 +++++++++++++++++++++++++
 include/drm/tinydrm/tinydrm-helpers.h          | 100 +++++
 4 files changed, 597 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
 create mode 100644 include/drm/tinydrm/tinydrm-helpers.h

Comments

Daniel Vetter Jan. 23, 2017, 9:32 a.m. UTC | #1

On Sun, Jan 22, 2017 at 07:11:13PM +0100, Noralf Trønnes wrote:
> Add common functionality needed by many tinydrm drivers.
> 
> Signed-off-by: Noralf Trønnes <[e-mail]>

Bunch of comments below, all optional.
-Daniel

> ---
>  Documentation/gpu/drm-kms-helpers.rst          |   6 +
>  drivers/gpu/drm/tinydrm/core/Makefile          |   2 +-
>  drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 490 +++++++++++++++++++++++++
>  include/drm/tinydrm/tinydrm-helpers.h          | 100 +++++
>  4 files changed, 597 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
>  create mode 100644 include/drm/tinydrm/tinydrm-helpers.h
> 
> diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst
> index a86bd7f..be07e76 100644
> --- a/Documentation/gpu/drm-kms-helpers.rst
> +++ b/Documentation/gpu/drm-kms-helpers.rst
> @@ -287,3 +287,9 @@ tinydrm Helper Reference
>  
>  .. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
>     :export:
> +
> +.. kernel-doc:: include/drm/tinydrm/tinydrm-helpers.h
> +   :internal:
> +
> +.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> +   :export:
> diff --git a/drivers/gpu/drm/tinydrm/core/Makefile b/drivers/gpu/drm/tinydrm/core/Makefile
> index 4f14a0f..fb221e6 100644
> --- a/drivers/gpu/drm/tinydrm/core/Makefile
> +++ b/drivers/gpu/drm/tinydrm/core/Makefile
> @@ -1,3 +1,3 @@
> -tinydrm-y := tinydrm-core.o tinydrm-pipe.o
> +tinydrm-y := tinydrm-core.o tinydrm-pipe.o tinydrm-helpers.o
>  
>  obj-$(CONFIG_DRM_TINYDRM) += tinydrm.o
> diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> new file mode 100644
> index 0000000..fc02e01
> --- /dev/null
> +++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> @@ -0,0 +1,490 @@
> +/*
> + * Copyright (C) 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.
> + */
> +
> +#include <drm/tinydrm/tinydrm.h>
> +#include <drm/tinydrm/tinydrm-helpers.h>
> +#include <linux/backlight.h>
> +#include <linux/pm.h>
> +#include <linux/spi/spi.h>
> +#include <linux/swab.h>
> +
> +static unsigned int spi_max;
> +module_param(spi_max, uint, 0400);
> +MODULE_PARM_DESC(spi_max, "Set a lower SPI max transfer size");
> +
> +/**
> + * tinydrm_merge_clips - Merge clip rectangles
> + * @dst: Destination clip rectangle
> + * @src: Source clip rectangle(s)
> + * @num_clips: Number of @src clip rectangles
> + * @flags: Dirty fb ioctl flags
> + * @max_width: Maximum width of @dst
> + * @max_height: Maximum height of @dst
> + *
> + * This function merges @src clip rectangle(s) into @dst. If @src is NULL,
> + * @max_width and @min_width is used to set a full @dst clip rectangle.
> + *
> + * Returns:
> + * true if it's a full clip, false otherwise
> + */
> +bool tinydrm_merge_clips(struct drm_clip_rect *dst,
> +			 struct drm_clip_rect *src, unsigned int num_clips,
> +			 unsigned int flags, u32 max_width, u32 max_height)
> +{
> +	unsigned int i;
> +
> +	if (!src || !num_clips) {
> +		dst->x1 = 0;
> +		dst->x2 = max_width;
> +		dst->y1 = 0;
> +		dst->y2 = max_height;
> +		return true;
> +	}
> +
> +	dst->x1 = ~0;
> +	dst->y1 = ~0;
> +	dst->x2 = 0;
> +	dst->y2 = 0;
> +
> +	for (i = 0; i < num_clips; i++) {
> +		if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY)
> +			i++;
> +		dst->x1 = min(dst->x1, src[i].x1);
> +		dst->x2 = max(dst->x2, src[i].x2);
> +		dst->y1 = min(dst->y1, src[i].y1);
> +		dst->y2 = max(dst->y2, src[i].y2);
> +	}
> +
> +	if (dst->x2 > max_width || dst->y2 > max_height ||
> +	    dst->x1 >= dst->x2 || dst->y1 >= dst->y2) {
> +		DRM_DEBUG_KMS("Illegal clip: x1=%u, x2=%u, y1=%u, y2=%u\n",
> +			      dst->x1, dst->x2, dst->y1, dst->y2);
> +		dst->x1 = 0;
> +		dst->y1 = 0;
> +		dst->x2 = max_width;
> +		dst->y2 = max_height;
> +	}
> +
> +	return (dst->x2 - dst->x1) == max_width &&
> +	       (dst->y2 - dst->y1) == max_height;
> +}
> +EXPORT_SYMBOL(tinydrm_merge_clips);

Argh, the drm_clip_rect vs. drm_rect confusion strikes again :(

> +
> +/**
> + * tinydrm_memcpy - Copy clip buffer
> + * @dst: Destination buffer
> + * @vaddr: Source buffer
> + * @fb: DRM framebuffer
> + * @clip: Clip rectangle area to copy
> + */
> +void tinydrm_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
> +		    struct drm_clip_rect *clip)
> +{
> +	unsigned int cpp = drm_format_plane_cpp(fb->format->format, 0);
> +	unsigned int pitch = fb->pitches[0];
> +	void *src = vaddr + (clip->y1 * pitch) + (clip->x1 * cpp);
> +	size_t len = (clip->x2 - clip->x1) * cpp;
> +	unsigned int y;
> +
> +	for (y = clip->y1; y < clip->y2; y++) {
> +		memcpy(dst, src, len);
> +		src += pitch;
> +		dst += len;
> +	}
> +}
> +EXPORT_SYMBOL(tinydrm_memcpy);
> +
> +/**
> + * tinydrm_swab16 - Swap bytes into clip buffer
> + * @dst: RGB565 destination buffer
> + * @vaddr: RGB565 source buffer
> + * @fb: DRM framebuffer
> + * @clip: Clip rectangle area to copy
> + */
> +
> +
> +/*
> +
> +FIXME
> +
> +Doing a memcpy to a temporary buffer before swapping bytes, increases
> +framerate by 26%, instead of swapping directly from the source buffer
> +which is drm_gem_cma_object->vaddr.
> +
> +Why is that?
> +
> +(swapping is needed because Raspberry Pi is Little Endian and doesn't
> +have 16-bit SPI support).
> +
> +# SPI @32MHz
> +$ modetest <...> 320x240@RG16 -v
> +
> +no tmp buffer
> +freq: 18.91Hz
> +
> +tmp buffer
> +freq: 23.98Hz
> +
> +
> +*/
> +static void *buf;
> +
> +void tinydrm_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
> +		    struct drm_clip_rect *clip)
> +{
> +#if 1
> +	unsigned int pitch = fb->pitches[0];
> +	unsigned int x, y;
> +	u16 *src;
> +
> +	if (!buf)
> +		buf = kmalloc(320 * 2, GFP_KERNEL);
> +	if (WARN_ON_ONCE(!buf))
> +		return;
> +
> +	for (y = clip->y1; y < clip->y2; y++) {
> +		src = vaddr + (y * pitch);
> +		src += clip->x1;
> +		memcpy(buf, src, (clip->x2 - clip->x1) * 2);
> +		src = buf;
> +		for (x = clip->x1; x < clip->x2; x++)
> +			*dst++ = swab16(*src++);
> +	}
> +#else
> +	unsigned int pitch = fb->pitches[0];
> +	unsigned int x, y;
> +	u16 *src;
> +
> +	for (y = clip->y1; y < clip->y2; y++) {
> +		src = vaddr + (y * pitch);
> +		src += clip->x1;
> +		for (x = clip->x1; x < clip->x2; x++)
> +			*dst++ = swab16(*src++);
> +	}
> +#endif
> +}
> +EXPORT_SYMBOL(tinydrm_swab16);
> +
> +/**
> + * tinydrm_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
> + * @dst: RGB565 destination buffer
> + * @vaddr: XRGB8888 source buffer
> + * @fb: DRM framebuffer
> + * @clip: Clip rectangle area to copy
> + * @swap: Swap bytes
> + *
> + * Drivers can use this function for RGB565 devices that don't natively
> + * support XRGB8888.
> + */
> +void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
> +				struct drm_framebuffer *fb,
> +				struct drm_clip_rect *clip, bool swap)
> +{
> +	unsigned int pitch = fb->pitches[0];
> +	unsigned int x, y;
> +	u16 val16;
> +	u32 *src;
> +
> +	for (y = clip->y1; y < clip->y2; y++) {
> +		src = vaddr + (y * pitch);
> +		src += clip->x1;
> +		for (x = clip->x1; x < clip->x2; x++) {
> +			val16 = ((*src & 0x00F80000) >> 8) |
> +				((*src & 0x0000FC00) >> 5) |
> +				((*src & 0x000000F8) >> 3);
> +			src++;
> +			if (swap)
> +				*dst++ = swab16(val16);
> +			else
> +				*dst++ = val16;
> +		}
> +	}
> +}
> +EXPORT_SYMBOL(tinydrm_xrgb8888_to_rgb565);

I wonder whether the above would make sense in drm core as some kind of fb
helpers. But we can do that once there's a clear need.

> +
> +#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
> +/**
> + * tinydrm_of_find_backlight - Find backlight device in device-tree
> + * @dev: Device
> + *
> + * This function looks for a DT node pointed to by a property named 'backlight'
> + * and uses of_find_backlight_by_node() to get the backlight device.
> + * Additionally if the brightness property is zero, it is set to
> + * max_brightness.
> + *
> + * Returns:
> + * NULL if there's no backlight property.
> + * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
> + * is found.
> + * If the backlight device is found, a pointer to the structure is returned.
> + */
> +struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
> +{
> +	struct backlight_device *backlight;
> +	struct device_node *np;
> +
> +	np = of_parse_phandle(dev->of_node, "backlight", 0);
> +	if (!np)
> +		return NULL;
> +
> +	backlight = of_find_backlight_by_node(np);
> +	of_node_put(np);
> +
> +	if (!backlight)
> +		return ERR_PTR(-EPROBE_DEFER);
> +
> +	if (!backlight->props.brightness) {
> +		backlight->props.brightness = backlight->props.max_brightness;
> +		DRM_DEBUG_KMS("Backlight brightness set to %d\n",
> +			      backlight->props.brightness);
> +	}

I
> +
> +	return backlight;
> +}
> +EXPORT_SYMBOL(tinydrm_of_find_backlight);
> +
> +/**
> + * tinydrm_enable_backlight - Enable backlight helper
> + * @backlight: Backlight device
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */
> +int tinydrm_enable_backlight(struct backlight_device *backlight)
> +{
> +	unsigned int old_state;
> +	int ret;
> +
> +	if (!backlight)
> +		return 0;
> +
> +	old_state = backlight->props.state;
> +	backlight->props.state &= ~BL_CORE_SUSPENDED;
> +	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
> +		      backlight->props.state);
> +
> +	ret = backlight_update_status(backlight);
> +	if (ret)
> +		DRM_ERROR("Failed to enable backlight %d\n", ret);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(tinydrm_enable_backlight);
> +
> +/**
> + * tinydrm_disable_backlight - Disable backlight helper
> + * @backlight: Backlight device
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */
> +int tinydrm_disable_backlight(struct backlight_device *backlight)
> +{
> +	unsigned int old_state;
> +	int ret;
> +
> +	if (!backlight)
> +		return 0;
> +
> +	old_state = backlight->props.state;
> +	backlight->props.state |= BL_CORE_SUSPENDED;
> +	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
> +		      backlight->props.state);
> +	ret = backlight_update_status(backlight);
> +	if (ret)
> +		DRM_ERROR("Failed to disable backlight %d\n", ret);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(tinydrm_disable_backlight);
> +#endif
> +
> +#ifdef CONFIG_SPI
> +
> +/**
> + * tinydrm_spi_max_transfer_size - Determine max SPI transfer size
> + * @spi: SPI device
> + * @max_len: Maximum buffer size needed (optional)
> + *
> + * This function returns the maximum size to use for SPI transfers. It checks
> + * the SPI master, the optional @max_len and the module parameter spi_max and
> + * returns the smallest.
> + *
> + * Returns:
> + * Maximum size for SPI transfers
> + */
> +size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len)
> +{
> +	size_t ret;
> +
> +	ret = min(spi_max_transfer_size(spi), spi->master->max_dma_len);
> +	if (max_len)
> +		ret = min(ret, max_len);
> +	if (spi_max)
> +		ret = min_t(size_t, ret, spi_max);
> +	ret &= ~0x3;
> +	if (ret < 4)
> +		ret = 4;
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(tinydrm_spi_max_transfer_size);
> +
> +/**
> + * tinydrm_spi_bpw_supported - Check if bits per word is supported
> + * @spi: SPI device
> + * @bpw: Bits per word
> + *
> + * This function checks to see if the SPI master driver supports @bpw.
> + *
> + * Returns:
> + * True if @bpw is supported, false otherwise.
> + */
> +bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw)
> +{
> +	u32 bpw_mask = spi->master->bits_per_word_mask;
> +
> +	if (bpw == 8)
> +		return true;
> +
> +	if (!bpw_mask) {
> +		dev_warn_once(&spi->dev,
> +			      "bits_per_word_mask not set, assume 8-bit only\n");
> +		return false;
> +	}
> +
> +	if (bpw_mask & SPI_BPW_MASK(bpw))
> +		return true;
> +
> +	return false;
> +}
> +EXPORT_SYMBOL(tinydrm_spi_bpw_supported);
> +
> +static void
> +tinydrm_dbg_spi_print(struct spi_device *spi, struct spi_transfer *tr,
> +		      const void *buf, int idx, bool tx)
> +{
> +	u32 speed_hz = tr->speed_hz ? tr->speed_hz : spi->max_speed_hz;
> +	char linebuf[3 * 32];
> +
> +	hex_dump_to_buffer(buf, tr->len, 16,
> +			   DIV_ROUND_UP(tr->bits_per_word, 8),
> +			   linebuf, sizeof(linebuf), false);
> +
> +	printk(KERN_DEBUG
> +	       "    tr(%i): speed=%u%s, bpw=%i, len=%u, %s_buf=[%s%s]\n", idx,
> +	       speed_hz > 1000000 ? speed_hz / 1000000 : speed_hz / 1000,
> +	       speed_hz > 1000000 ? "MHz" : "kHz", tr->bits_per_word, tr->len,
> +	       tx ? "tx" : "rx", linebuf, tr->len > 16 ? " ..." : "");
> +}
> +
> +/* called through tinydrm_dbg_spi_message() */
> +void _tinydrm_dbg_spi_message(struct spi_device *spi, struct spi_message *m)
> +{
> +	struct spi_transfer *tmp;
> +	struct list_head *pos;
> +	int i = 0;
> +
> +	list_for_each(pos, &m->transfers) {
> +		tmp = list_entry(pos, struct spi_transfer, transfer_list);
> +
> +		if (tmp->tx_buf)
> +			tinydrm_dbg_spi_print(spi, tmp, tmp->tx_buf, i, true);
> +		if (tmp->rx_buf)
> +			tinydrm_dbg_spi_print(spi, tmp, tmp->rx_buf, i, false);
> +		i++;
> +	}
> +}
> +EXPORT_SYMBOL(_tinydrm_dbg_spi_message);
> +
> +/**
> + * tinydrm_spi_transfer - SPI transfer helper
> + * @spi: SPI device
> + * @speed_hz: Override speed (optional)
> + * @header: Optional header transfer
> + * @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 master driver can handle. If the machine is Little Endian and the
> + * SPI master driver doesn't support 16 bits per word, it swaps the bytes and
> + * does a 8-bit transfer.
> + * If @header is set, it is prepended to each SPI message.
> + *
> + * Returns:
> + * Zero on success, negative error code on failure.
> + */
> +int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
> +			 struct spi_transfer *header, u8 bpw, const void *buf,
> +			 size_t len)
> +{
> +	struct spi_transfer tr = {
> +		.bits_per_word = bpw,
> +		.speed_hz = speed_hz,
> +	};
> +	struct spi_message m;
> +	u16 *swap_buf = NULL;
> +	size_t max_chunk;
> +	size_t chunk;
> +	int ret = 0;
> +
> +	if (WARN_ON_ONCE(bpw != 8 && bpw != 16))
> +		return -EINVAL;
> +
> +	max_chunk = tinydrm_spi_max_transfer_size(spi, 0);
> +
> +	if (drm_debug & DRM_UT_DRIVER)
> +		pr_debug("[drm:%s] bpw=%u, max_chunk=%zu, transfers:\n",
> +			 __func__, bpw, max_chunk);
> +
> +	if (bpw == 16 && !tinydrm_spi_bpw_supported(spi, 16)) {
> +		tr.bits_per_word = 8;
> +		if (tinydrm_machine_little_endian()) {
> +			swap_buf = kmalloc(min(len, max_chunk), GFP_KERNEL);
> +			if (!swap_buf)
> +				return -ENOMEM;
> +		}
> +	}
> +
> +	spi_message_init(&m);
> +	if (header)
> +		spi_message_add_tail(header, &m);
> +	spi_message_add_tail(&tr, &m);
> +
> +	while (len) {
> +		chunk = min(len, max_chunk);
> +
> +		tr.tx_buf = buf;
> +		tr.len = chunk;
> +
> +		if (swap_buf) {
> +			const u16 *buf16 = buf;
> +			unsigned int i;
> +
> +			for (i = 0; i < chunk / 2; i++)
> +				swap_buf[i] = swab16(buf16[i]);
> +
> +			tr.tx_buf = swap_buf;
> +		}
> +
> +		buf += chunk;
> +		len -= chunk;
> +
> +		tinydrm_dbg_spi_message(spi, &m);
> +		ret = spi_sync(spi, &m);
> +		if (ret)
> +			return ret;
> +	};
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(tinydrm_spi_transfer);

Hm, might be worth it to try and move the spi helpers into the spi core
code. But imo better to merge this now and move later on, than delay
merging tinydrm.

> +
> +#endif /* CONFIG_SPI */
> diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
> new file mode 100644
> index 0000000..78175fe
> --- /dev/null
> +++ b/include/drm/tinydrm/tinydrm-helpers.h
> @@ -0,0 +1,100 @@
> +/*
> + * Copyright (C) 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_TINYDRM_HELPERS_H
> +#define __LINUX_TINYDRM_HELPERS_H
> +
> +struct backlight_device;
> +struct tinydrm_device;
> +struct drm_clip_rect;
> +struct spi_transfer;
> +struct spi_message;
> +struct spi_device;
> +struct device;
> +
> +/**
> + * tinydrm_machine_little_endian - Machine is little endian
> + *
> + * Returns:
> + * true if *defined(__LITTLE_ENDIAN)*, false otherwise
> + */
> +static inline bool tinydrm_machine_little_endian(void)
> +{
> +#if defined(__LITTLE_ENDIAN)
> +	return true;
> +#else
> +	return false;
> +#endif
> +}
> +
> +bool tinydrm_merge_clips(struct drm_clip_rect *dst,
> +			 struct drm_clip_rect *src, unsigned int num_clips,
> +			 unsigned int flags, u32 max_width, u32 max_height);
> +void tinydrm_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
> +		    struct drm_clip_rect *clip);
> +void tinydrm_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
> +		    struct drm_clip_rect *clip);
> +void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
> +				struct drm_framebuffer *fb,
> +				struct drm_clip_rect *clip, bool swap);
> +
> +#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
> +struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
> +int tinydrm_enable_backlight(struct backlight_device *backlight);
> +int tinydrm_disable_backlight(struct backlight_device *backlight);
> +#else
> +static inline struct backlight_device *
> +tinydrm_of_find_backlight(struct device *dev)
> +{
> +	return NULL;
> +}
> +
> +static inline int tinydrm_enable_backlight(struct backlight_device *backlight)
> +{
> +	return 0;
> +}
> +
> +static inline int
> +tinydrm_disable_backlight(struct backlight_device *backlight)
> +{
> +	return 0;
> +}
> +#endif
> +
> +size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
> +bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
> +int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
> +			 struct spi_transfer *header, u8 bpw, const void *buf,
> +			 size_t len);
> +void _tinydrm_dbg_spi_message(struct spi_device *spi, struct spi_message *m);
> +
> +#ifdef DEBUG
> +/**
> + * tinydrm_dbg_spi_message - Dump SPI message
> + * @spi: SPI device
> + * @m: SPI message
> + *
> + * Dumps info about the transfers in a SPI message including buffer content.
> + * DEBUG has to be defined for this function to be enabled alongside setting
> + * the DRM_UT_DRIVER bit of &drm_debug.
> + */
> +static inline void tinydrm_dbg_spi_message(struct spi_device *spi,
> +					   struct spi_message *m)
> +{
> +	if (drm_debug & DRM_UT_DRIVER)
> +		_tinydrm_dbg_spi_message(spi, m);
> +}
> +#else
> +static inline void tinydrm_dbg_spi_message(struct spi_device *spi,
> +					   struct spi_message *m)
> +{
> +}
> +#endif /* DEBUG */
> +
> +#endif /* __LINUX_TINYDRM_HELPERS_H */
> -- 
> 2.10.2
> 
> _______________________________________________
> dri-devel mailing list
> [e-mail]
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Patch

diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst
index a86bd7f..be07e76 100644
--- a/Documentation/gpu/drm-kms-helpers.rst
+++ b/Documentation/gpu/drm-kms-helpers.rst
@@ -287,3 +287,9 @@  tinydrm Helper Reference
 
 .. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
    :export:
+
+.. kernel-doc:: include/drm/tinydrm/tinydrm-helpers.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
+   :export:
diff --git a/drivers/gpu/drm/tinydrm/core/Makefile b/drivers/gpu/drm/tinydrm/core/Makefile
index 4f14a0f..fb221e6 100644
--- a/drivers/gpu/drm/tinydrm/core/Makefile
+++ b/drivers/gpu/drm/tinydrm/core/Makefile
@@ -1,3 +1,3 @@ 
-tinydrm-y := tinydrm-core.o tinydrm-pipe.o
+tinydrm-y := tinydrm-core.o tinydrm-pipe.o tinydrm-helpers.o
 
 obj-$(CONFIG_DRM_TINYDRM) += tinydrm.o
diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
new file mode 100644
index 0000000..fc02e01
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
@@ -0,0 +1,490 @@ 
+/*
+ * Copyright (C) 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.
+ */
+
+#include <drm/tinydrm/tinydrm.h>
+#include <drm/tinydrm/tinydrm-helpers.h>
+#include <linux/backlight.h>
+#include <linux/pm.h>
+#include <linux/spi/spi.h>
+#include <linux/swab.h>
+
+static unsigned int spi_max;
+module_param(spi_max, uint, 0400);
+MODULE_PARM_DESC(spi_max, "Set a lower SPI max transfer size");
+
+/**
+ * tinydrm_merge_clips - Merge clip rectangles
+ * @dst: Destination clip rectangle
+ * @src: Source clip rectangle(s)
+ * @num_clips: Number of @src clip rectangles
+ * @flags: Dirty fb ioctl flags
+ * @max_width: Maximum width of @dst
+ * @max_height: Maximum height of @dst
+ *
+ * This function merges @src clip rectangle(s) into @dst. If @src is NULL,
+ * @max_width and @min_width is used to set a full @dst clip rectangle.
+ *
+ * Returns:
+ * true if it's a full clip, false otherwise
+ */
+bool tinydrm_merge_clips(struct drm_clip_rect *dst,
+			 struct drm_clip_rect *src, unsigned int num_clips,
+			 unsigned int flags, u32 max_width, u32 max_height)
+{
+	unsigned int i;
+
+	if (!src || !num_clips) {
+		dst->x1 = 0;
+		dst->x2 = max_width;
+		dst->y1 = 0;
+		dst->y2 = max_height;
+		return true;
+	}
+
+	dst->x1 = ~0;
+	dst->y1 = ~0;
+	dst->x2 = 0;
+	dst->y2 = 0;
+
+	for (i = 0; i < num_clips; i++) {
+		if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY)
+			i++;
+		dst->x1 = min(dst->x1, src[i].x1);
+		dst->x2 = max(dst->x2, src[i].x2);
+		dst->y1 = min(dst->y1, src[i].y1);
+		dst->y2 = max(dst->y2, src[i].y2);
+	}
+
+	if (dst->x2 > max_width || dst->y2 > max_height ||
+	    dst->x1 >= dst->x2 || dst->y1 >= dst->y2) {
+		DRM_DEBUG_KMS("Illegal clip: x1=%u, x2=%u, y1=%u, y2=%u\n",
+			      dst->x1, dst->x2, dst->y1, dst->y2);
+		dst->x1 = 0;
+		dst->y1 = 0;
+		dst->x2 = max_width;
+		dst->y2 = max_height;
+	}
+
+	return (dst->x2 - dst->x1) == max_width &&
+	       (dst->y2 - dst->y1) == max_height;
+}
+EXPORT_SYMBOL(tinydrm_merge_clips);
+
+/**
+ * tinydrm_memcpy - Copy clip buffer
+ * @dst: Destination buffer
+ * @vaddr: Source buffer
+ * @fb: DRM framebuffer
+ * @clip: Clip rectangle area to copy
+ */
+void tinydrm_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
+		    struct drm_clip_rect *clip)
+{
+	unsigned int cpp = drm_format_plane_cpp(fb->format->format, 0);
+	unsigned int pitch = fb->pitches[0];
+	void *src = vaddr + (clip->y1 * pitch) + (clip->x1 * cpp);
+	size_t len = (clip->x2 - clip->x1) * cpp;
+	unsigned int y;
+
+	for (y = clip->y1; y < clip->y2; y++) {
+		memcpy(dst, src, len);
+		src += pitch;
+		dst += len;
+	}
+}
+EXPORT_SYMBOL(tinydrm_memcpy);
+
+/**
+ * tinydrm_swab16 - Swap bytes into clip buffer
+ * @dst: RGB565 destination buffer
+ * @vaddr: RGB565 source buffer
+ * @fb: DRM framebuffer
+ * @clip: Clip rectangle area to copy
+ */
+
+
+/*
+
+FIXME
+
+Doing a memcpy to a temporary buffer before swapping bytes, increases
+framerate by 26%, instead of swapping directly from the source buffer
+which is drm_gem_cma_object->vaddr.
+
+Why is that?
+
+(swapping is needed because Raspberry Pi is Little Endian and doesn't
+have 16-bit SPI support).
+
+# SPI @32MHz
+$ modetest <...> 320x240@RG16 -v
+
+no tmp buffer
+freq: 18.91Hz
+
+tmp buffer
+freq: 23.98Hz
+
+
+*/
+static void *buf;
+
+void tinydrm_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
+		    struct drm_clip_rect *clip)
+{
+#if 1
+	unsigned int pitch = fb->pitches[0];
+	unsigned int x, y;
+	u16 *src;
+
+	if (!buf)
+		buf = kmalloc(320 * 2, GFP_KERNEL);
+	if (WARN_ON_ONCE(!buf))
+		return;
+
+	for (y = clip->y1; y < clip->y2; y++) {
+		src = vaddr + (y * pitch);
+		src += clip->x1;
+		memcpy(buf, src, (clip->x2 - clip->x1) * 2);
+		src = buf;
+		for (x = clip->x1; x < clip->x2; x++)
+			*dst++ = swab16(*src++);
+	}
+#else
+	unsigned int pitch = fb->pitches[0];
+	unsigned int x, y;
+	u16 *src;
+
+	for (y = clip->y1; y < clip->y2; y++) {
+		src = vaddr + (y * pitch);
+		src += clip->x1;
+		for (x = clip->x1; x < clip->x2; x++)
+			*dst++ = swab16(*src++);
+	}
+#endif
+}
+EXPORT_SYMBOL(tinydrm_swab16);
+
+/**
+ * tinydrm_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
+ * @dst: RGB565 destination buffer
+ * @vaddr: XRGB8888 source buffer
+ * @fb: DRM framebuffer
+ * @clip: Clip rectangle area to copy
+ * @swap: Swap bytes
+ *
+ * Drivers can use this function for RGB565 devices that don't natively
+ * support XRGB8888.
+ */
+void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
+				struct drm_framebuffer *fb,
+				struct drm_clip_rect *clip, bool swap)
+{
+	unsigned int pitch = fb->pitches[0];
+	unsigned int x, y;
+	u16 val16;
+	u32 *src;
+
+	for (y = clip->y1; y < clip->y2; y++) {
+		src = vaddr + (y * pitch);
+		src += clip->x1;
+		for (x = clip->x1; x < clip->x2; x++) {
+			val16 = ((*src & 0x00F80000) >> 8) |
+				((*src & 0x0000FC00) >> 5) |
+				((*src & 0x000000F8) >> 3);
+			src++;
+			if (swap)
+				*dst++ = swab16(val16);
+			else
+				*dst++ = val16;
+		}
+	}
+}
+EXPORT_SYMBOL(tinydrm_xrgb8888_to_rgb565);
+
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+/**
+ * tinydrm_of_find_backlight - Find backlight device in device-tree
+ * @dev: Device
+ *
+ * This function looks for a DT node pointed to by a property named 'backlight'
+ * and uses of_find_backlight_by_node() to get the backlight device.
+ * Additionally if the brightness property is zero, it is set to
+ * max_brightness.
+ *
+ * Returns:
+ * NULL if there's no backlight property.
+ * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
+ * is found.
+ * If the backlight device is found, a pointer to the structure is returned.
+ */
+struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
+{
+	struct backlight_device *backlight;
+	struct device_node *np;
+
+	np = of_parse_phandle(dev->of_node, "backlight", 0);
+	if (!np)
+		return NULL;
+
+	backlight = of_find_backlight_by_node(np);
+	of_node_put(np);
+
+	if (!backlight)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	if (!backlight->props.brightness) {
+		backlight->props.brightness = backlight->props.max_brightness;
+		DRM_DEBUG_KMS("Backlight brightness set to %d\n",
+			      backlight->props.brightness);
+	}
+
+	return backlight;
+}
+EXPORT_SYMBOL(tinydrm_of_find_backlight);
+
+/**
+ * tinydrm_enable_backlight - Enable backlight helper
+ * @backlight: Backlight device
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int tinydrm_enable_backlight(struct backlight_device *backlight)
+{
+	unsigned int old_state;
+	int ret;
+
+	if (!backlight)
+		return 0;
+
+	old_state = backlight->props.state;
+	backlight->props.state &= ~BL_CORE_SUSPENDED;
+	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
+		      backlight->props.state);
+
+	ret = backlight_update_status(backlight);
+	if (ret)
+		DRM_ERROR("Failed to enable backlight %d\n", ret);
+
+	return ret;
+}
+EXPORT_SYMBOL(tinydrm_enable_backlight);
+
+/**
+ * tinydrm_disable_backlight - Disable backlight helper
+ * @backlight: Backlight device
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int tinydrm_disable_backlight(struct backlight_device *backlight)
+{
+	unsigned int old_state;
+	int ret;
+
+	if (!backlight)
+		return 0;
+
+	old_state = backlight->props.state;
+	backlight->props.state |= BL_CORE_SUSPENDED;
+	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
+		      backlight->props.state);
+	ret = backlight_update_status(backlight);
+	if (ret)
+		DRM_ERROR("Failed to disable backlight %d\n", ret);
+
+	return ret;
+}
+EXPORT_SYMBOL(tinydrm_disable_backlight);
+#endif
+
+#ifdef CONFIG_SPI
+
+/**
+ * tinydrm_spi_max_transfer_size - Determine max SPI transfer size
+ * @spi: SPI device
+ * @max_len: Maximum buffer size needed (optional)
+ *
+ * This function returns the maximum size to use for SPI transfers. It checks
+ * the SPI master, the optional @max_len and the module parameter spi_max and
+ * returns the smallest.
+ *
+ * Returns:
+ * Maximum size for SPI transfers
+ */
+size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len)
+{
+	size_t ret;
+
+	ret = min(spi_max_transfer_size(spi), spi->master->max_dma_len);
+	if (max_len)
+		ret = min(ret, max_len);
+	if (spi_max)
+		ret = min_t(size_t, ret, spi_max);
+	ret &= ~0x3;
+	if (ret < 4)
+		ret = 4;
+
+	return ret;
+}
+EXPORT_SYMBOL(tinydrm_spi_max_transfer_size);
+
+/**
+ * tinydrm_spi_bpw_supported - Check if bits per word is supported
+ * @spi: SPI device
+ * @bpw: Bits per word
+ *
+ * This function checks to see if the SPI master driver supports @bpw.
+ *
+ * Returns:
+ * True if @bpw is supported, false otherwise.
+ */
+bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw)
+{
+	u32 bpw_mask = spi->master->bits_per_word_mask;
+
+	if (bpw == 8)
+		return true;
+
+	if (!bpw_mask) {
+		dev_warn_once(&spi->dev,
+			      "bits_per_word_mask not set, assume 8-bit only\n");
+		return false;
+	}
+
+	if (bpw_mask & SPI_BPW_MASK(bpw))
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(tinydrm_spi_bpw_supported);
+
+static void
+tinydrm_dbg_spi_print(struct spi_device *spi, struct spi_transfer *tr,
+		      const void *buf, int idx, bool tx)
+{
+	u32 speed_hz = tr->speed_hz ? tr->speed_hz : spi->max_speed_hz;
+	char linebuf[3 * 32];
+
+	hex_dump_to_buffer(buf, tr->len, 16,
+			   DIV_ROUND_UP(tr->bits_per_word, 8),
+			   linebuf, sizeof(linebuf), false);
+
+	printk(KERN_DEBUG
+	       "    tr(%i): speed=%u%s, bpw=%i, len=%u, %s_buf=[%s%s]\n", idx,
+	       speed_hz > 1000000 ? speed_hz / 1000000 : speed_hz / 1000,
+	       speed_hz > 1000000 ? "MHz" : "kHz", tr->bits_per_word, tr->len,
+	       tx ? "tx" : "rx", linebuf, tr->len > 16 ? " ..." : "");
+}
+
+/* called through tinydrm_dbg_spi_message() */
+void _tinydrm_dbg_spi_message(struct spi_device *spi, struct spi_message *m)
+{
+	struct spi_transfer *tmp;
+	struct list_head *pos;
+	int i = 0;
+
+	list_for_each(pos, &m->transfers) {
+		tmp = list_entry(pos, struct spi_transfer, transfer_list);
+
+		if (tmp->tx_buf)
+			tinydrm_dbg_spi_print(spi, tmp, tmp->tx_buf, i, true);
+		if (tmp->rx_buf)
+			tinydrm_dbg_spi_print(spi, tmp, tmp->rx_buf, i, false);
+		i++;
+	}
+}
+EXPORT_SYMBOL(_tinydrm_dbg_spi_message);
+
+/**
+ * tinydrm_spi_transfer - SPI transfer helper
+ * @spi: SPI device
+ * @speed_hz: Override speed (optional)
+ * @header: Optional header transfer
+ * @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 master driver can handle. If the machine is Little Endian and the
+ * SPI master driver doesn't support 16 bits per word, it swaps the bytes and
+ * does a 8-bit transfer.
+ * If @header is set, it is prepended to each SPI message.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
+			 struct spi_transfer *header, u8 bpw, const void *buf,
+			 size_t len)
+{
+	struct spi_transfer tr = {
+		.bits_per_word = bpw,
+		.speed_hz = speed_hz,
+	};
+	struct spi_message m;
+	u16 *swap_buf = NULL;
+	size_t max_chunk;
+	size_t chunk;
+	int ret = 0;
+
+	if (WARN_ON_ONCE(bpw != 8 && bpw != 16))
+		return -EINVAL;
+
+	max_chunk = tinydrm_spi_max_transfer_size(spi, 0);
+
+	if (drm_debug & DRM_UT_DRIVER)
+		pr_debug("[drm:%s] bpw=%u, max_chunk=%zu, transfers:\n",
+			 __func__, bpw, max_chunk);
+
+	if (bpw == 16 && !tinydrm_spi_bpw_supported(spi, 16)) {
+		tr.bits_per_word = 8;
+		if (tinydrm_machine_little_endian()) {
+			swap_buf = kmalloc(min(len, max_chunk), GFP_KERNEL);
+			if (!swap_buf)
+				return -ENOMEM;
+		}
+	}
+
+	spi_message_init(&m);
+	if (header)
+		spi_message_add_tail(header, &m);
+	spi_message_add_tail(&tr, &m);
+
+	while (len) {
+		chunk = min(len, max_chunk);
+
+		tr.tx_buf = buf;
+		tr.len = chunk;
+
+		if (swap_buf) {
+			const u16 *buf16 = buf;
+			unsigned int i;
+
+			for (i = 0; i < chunk / 2; i++)
+				swap_buf[i] = swab16(buf16[i]);
+
+			tr.tx_buf = swap_buf;
+		}
+
+		buf += chunk;
+		len -= chunk;
+
+		tinydrm_dbg_spi_message(spi, &m);
+		ret = spi_sync(spi, &m);
+		if (ret)
+			return ret;
+	};
+
+	return 0;
+}
+EXPORT_SYMBOL(tinydrm_spi_transfer);
+
+#endif /* CONFIG_SPI */
diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
new file mode 100644
index 0000000..78175fe
--- /dev/null
+++ b/include/drm/tinydrm/tinydrm-helpers.h
@@ -0,0 +1,100 @@ 
+/*
+ * Copyright (C) 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_TINYDRM_HELPERS_H
+#define __LINUX_TINYDRM_HELPERS_H
+
+struct backlight_device;
+struct tinydrm_device;
+struct drm_clip_rect;
+struct spi_transfer;
+struct spi_message;
+struct spi_device;
+struct device;
+
+/**
+ * tinydrm_machine_little_endian - Machine is little endian
+ *
+ * Returns:
+ * true if *defined(__LITTLE_ENDIAN)*, false otherwise
+ */
+static inline bool tinydrm_machine_little_endian(void)
+{
+#if defined(__LITTLE_ENDIAN)
+	return true;
+#else
+	return false;
+#endif
+}
+
+bool tinydrm_merge_clips(struct drm_clip_rect *dst,
+			 struct drm_clip_rect *src, unsigned int num_clips,
+			 unsigned int flags, u32 max_width, u32 max_height);
+void tinydrm_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
+		    struct drm_clip_rect *clip);
+void tinydrm_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
+		    struct drm_clip_rect *clip);
+void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
+				struct drm_framebuffer *fb,
+				struct drm_clip_rect *clip, bool swap);
+
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
+int tinydrm_enable_backlight(struct backlight_device *backlight);
+int tinydrm_disable_backlight(struct backlight_device *backlight);
+#else
+static inline struct backlight_device *
+tinydrm_of_find_backlight(struct device *dev)
+{
+	return NULL;
+}
+
+static inline int tinydrm_enable_backlight(struct backlight_device *backlight)
+{
+	return 0;
+}
+
+static inline int
+tinydrm_disable_backlight(struct backlight_device *backlight)
+{
+	return 0;
+}
+#endif
+
+size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
+bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
+int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
+			 struct spi_transfer *header, u8 bpw, const void *buf,
+			 size_t len);
+void _tinydrm_dbg_spi_message(struct spi_device *spi, struct spi_message *m);
+
+#ifdef DEBUG
+/**
+ * tinydrm_dbg_spi_message - Dump SPI message
+ * @spi: SPI device
+ * @m: SPI message
+ *
+ * Dumps info about the transfers in a SPI message including buffer content.
+ * DEBUG has to be defined for this function to be enabled alongside setting
+ * the DRM_UT_DRIVER bit of &drm_debug.
+ */
+static inline void tinydrm_dbg_spi_message(struct spi_device *spi,
+					   struct spi_message *m)
+{
+	if (drm_debug & DRM_UT_DRIVER)
+		_tinydrm_dbg_spi_message(spi, m);
+}
+#else
+static inline void tinydrm_dbg_spi_message(struct spi_device *spi,
+					   struct spi_message *m)
+{
+}
+#endif /* DEBUG */
+
+#endif /* __LINUX_TINYDRM_HELPERS_H */