[PATCH v4 2/7] drm/tinydrm: Add helper functions

Noralf Trønnes
2017-02-11T18:49:13Z

Add common functionality needed by many tinydrm drivers.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Thierry Reding <treding@nvidia.com>
---

Changes since version 3:
- Fix backlight dependency by selecting it
- Use #if IS_ENABLED(CONFIG_SPI) instead of #ifdef to handle tristate

Documentation/gpu/tinydrm.rst | 9 +
drivers/gpu/drm/tinydrm/Kconfig | 2 +
drivers/gpu/drm/tinydrm/core/Makefile | 2 +-
drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 460 +++++++++++++++++++++++++
include/drm/tinydrm/tinydrm-helpers.h | 100 ++++++
5 files changed, 572 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/tinydrm.rst b/Documentation/gpu/tinydrm.rst
index ec4a20d..fb256d2 100644
--- a/Documentation/gpu/tinydrm.rst
+++ b/Documentation/gpu/tinydrm.rst
@@ -19,3 +19,12 @@ Core functionality

.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
:export:
+
+Additional helpers
+==================
+
+.. 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/Kconfig b/drivers/gpu/drm/tinydrm/Kconfig
index ffb873f..adf3626 100644
--- a/drivers/gpu/drm/tinydrm/Kconfig
+++ b/drivers/gpu/drm/tinydrm/Kconfig
@@ -3,6 +3,8 @@ menuconfig DRM_TINYDRM
depends on DRM
select DRM_KMS_HELPER
select DRM_KMS_CMA_HELPER
+ select BACKLIGHT_LCD_SUPPORT
+ select BACKLIGHT_CLASS_DEVICE
help
Choose this option if you have a tinydrm supported display.
If M is selected the module will be called tinydrm.
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..3ccda6c
--- /dev/null
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
@@ -0,0 +1,460 @@
+/*
+ * 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
+ */
+void tinydrm_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
+ struct drm_clip_rect *clip)
+{
+ size_t len = (clip->x2 - clip->x1) * sizeof(u16);
+ unsigned int x, y;
+ u16 *src, *buf;
+
+ /*
+ * The cma memory is write-combined so reads are uncached.
+ * Speed up by fetching one line at a time.
+ */
+ buf = kmalloc(len, GFP_KERNEL);
+ if (!buf)
+ return;
+
+ for (y = clip->y1; y < clip->y2; y++) {
+ src = vaddr + (y * fb->pitches[0]);
+ src += clip->x1;
+ memcpy(buf, src, len);
+ src = buf;
+ for (x = clip->x1; x < clip->x2; x++)
+ *dst++ = swab16(*src++);
+ }
+
+ kfree(buf);
+}
+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)
+{
+ size_t len = (clip->x2 - clip->x1) * sizeof(u32);
+ unsigned int x, y;
+ u32 *src, *buf;
+ u16 val16;
+
+ buf = kmalloc(len, GFP_KERNEL);
+ if (!buf)
+ return;
+
+ for (y = clip->y1; y < clip->y2; y++) {
+ src = vaddr + (y * fb->pitches[0]);
+ src += clip->x1;
+ memcpy(buf, src, len);
+ src = buf;
+ 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;
+ }
+ }
+
+ kfree(buf);
+}
+EXPORT_SYMBOL(tinydrm_xrgb8888_to_rgb565);
+
+/**
+ * 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_FBBLANK;
+ 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_FBBLANK;
+ 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);
+
+#if IS_ENABLED(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 */
--
2.10.2