--- /dev/null
+/*
+ * Copyright (C) 2012 Red Hat
+ * based in parts on udlfb.c:
+ * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
+ * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
+ * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License v2. See the file COPYING in the main directory of this archive for
+ * more details.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/fb.h>
+#include <linux/prefetch.h>
+
+#include <drm/drmP.h>
+#include "udl_drv.h"
+
+#define MAX_CMD_PIXELS 255
+
+#define RLX_HEADER_BYTES 7
+#define MIN_RLX_PIX_BYTES 4
+#define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)
+
+#define RLE_HEADER_BYTES 6
+#define MIN_RLE_PIX_BYTES 3
+#define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)
+
+#define RAW_HEADER_BYTES 6
+#define MIN_RAW_PIX_BYTES 2
+#define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)
+
+/*
+ * Trims identical data from front and back of line
+ * Sets new front buffer address and width
+ * And returns byte count of identical pixels
+ * Assumes CPU natural alignment (unsigned long)
+ * for back and front buffer ptrs and width
+ */
+#if 0
+static int udl_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
+{
+ int j, k;
+ const unsigned long *back = (const unsigned long *) bback;
+ const unsigned long *front = (const unsigned long *) *bfront;
+ const int width = *width_bytes / sizeof(unsigned long);
+ int identical = width;
+ int start = width;
+ int end = width;
+
+ prefetch((void *) front);
+ prefetch((void *) back);
+
+ for (j = 0; j < width; j++) {
+ if (back[j] != front[j]) {
+ start = j;
+ break;
+ }
+ }
+
+ for (k = width - 1; k > j; k--) {
+ if (back[k] != front[k]) {
+ end = k+1;
+ break;
+ }
+ }
+
+ identical = start + (width - end);
+ *bfront = (u8 *) &front[start];
+ *width_bytes = (end - start) * sizeof(unsigned long);
+
+ return identical * sizeof(unsigned long);
+}
+#endif
+
+static inline u16 pixel32_to_be16(const uint32_t pixel)
+{
+ return (((pixel >> 3) & 0x001f) |
+ ((pixel >> 5) & 0x07e0) |
+ ((pixel >> 8) & 0xf800));
+}
+
+static inline u16 get_pixel_val16(const uint8_t *pixel, int bpp)
+{
+ u16 pixel_val16 = 0;
+ if (bpp == 2)
+ pixel_val16 = *(const uint16_t *)pixel;
+ else if (bpp == 4)
+ pixel_val16 = pixel32_to_be16(*(const uint32_t *)pixel);
+ return pixel_val16;
+}
+
+/*
+ * Render a command stream for an encoded horizontal line segment of pixels.
+ *
+ * A command buffer holds several commands.
+ * It always begins with a fresh command header
+ * (the protocol doesn't require this, but we enforce it to allow
+ * multiple buffers to be potentially encoded and sent in parallel).
+ * A single command encodes one contiguous horizontal line of pixels
+ *
+ * The function relies on the client to do all allocation, so that
+ * rendering can be done directly to output buffers (e.g. USB URBs).
+ * The function fills the supplied command buffer, providing information
+ * on where it left off, so the client may call in again with additional
+ * buffers if the line will take several buffers to complete.
+ *
+ * A single command can transmit a maximum of 256 pixels,
+ * regardless of the compression ratio (protocol design limit).
+ * To the hardware, 0 for a size byte means 256
+ *
+ * Rather than 256 pixel commands which are either rl or raw encoded,
+ * the rlx command simply assumes alternating raw and rl spans within one cmd.
+ * This has a slightly larger header overhead, but produces more even results.
+ * It also processes all data (read and write) in a single pass.
+ * Performance benchmarks of common cases show it having just slightly better
+ * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
+ * But for very rl friendly data, will compress not quite as well.
+ */
+static void udl_compress_hline16(
+ const u8 **pixel_start_ptr,
+ const u8 *const pixel_end,
+ uint32_t *device_address_ptr,
+ uint8_t **command_buffer_ptr,
+ const uint8_t *const cmd_buffer_end, int bpp)
+{
+ const u8 *pixel = *pixel_start_ptr;
+ uint32_t dev_addr = *device_address_ptr;
+ uint8_t *cmd = *command_buffer_ptr;
+
+ while ((pixel_end > pixel) &&
+ (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
+ uint8_t *raw_pixels_count_byte = NULL;
+ uint8_t *cmd_pixels_count_byte = NULL;
+ const u8 *raw_pixel_start = NULL;
+ const u8 *cmd_pixel_start, *cmd_pixel_end = NULL;
+ uint16_t pixel_val16;
+
+ prefetchw((void *) cmd); /* pull in one cache line at least */
+
+ *cmd++ = 0xaf;
+ *cmd++ = 0x6b;
+ *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
+ *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
+ *cmd++ = (uint8_t) ((dev_addr) & 0xFF);
+
+ cmd_pixels_count_byte = cmd++; /* we'll know this later */
+ cmd_pixel_start = pixel;
+
+ raw_pixels_count_byte = cmd++; /* we'll know this later */
+ raw_pixel_start = pixel;
+
+ cmd_pixel_end = pixel + (min(MAX_CMD_PIXELS + 1,
+ min((int)(pixel_end - pixel) / bpp,
+ (int)(cmd_buffer_end - cmd) / 2))) * bpp;
+
+ prefetch_range((void *) pixel, (cmd_pixel_end - pixel) * bpp);
+ pixel_val16 = get_pixel_val16(pixel, bpp);
+
+ while (pixel < cmd_pixel_end) {
+ const u8 *const start = pixel;
+ const uint16_t repeating_pixel_val16 = pixel_val16;
+
+ *(uint16_t *)cmd = cpu_to_be16(pixel_val16);
+
+ cmd += 2;
+ pixel += bpp;
+
+ while (pixel < cmd_pixel_end) {
+ pixel_val16 = get_pixel_val16(pixel, bpp);
+ if (pixel_val16 != repeating_pixel_val16)
+ break;
+ pixel += bpp;
+ }
+
+ if (unlikely(pixel > start + bpp)) {
+ /* go back and fill in raw pixel count */
+ *raw_pixels_count_byte = (((start -
+ raw_pixel_start) / bpp) + 1) & 0xFF;
+
+ /* immediately after raw data is repeat byte */
+ *cmd++ = (((pixel - start) / bpp) - 1) & 0xFF;
+
+ /* Then start another raw pixel span */
+ raw_pixel_start = pixel;
+ raw_pixels_count_byte = cmd++;
+ }
+ }
+
+ if (pixel > raw_pixel_start) {
+ /* finalize last RAW span */
+ *raw_pixels_count_byte = ((pixel-raw_pixel_start) / bpp) & 0xFF;
+ }
+
+ *cmd_pixels_count_byte = ((pixel - cmd_pixel_start) / bpp) & 0xFF;
+ dev_addr += ((pixel - cmd_pixel_start) / bpp) * 2;
+ }
+
+ if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
+ /* Fill leftover bytes with no-ops */
+ if (cmd_buffer_end > cmd)
+ memset(cmd, 0xAF, cmd_buffer_end - cmd);
+ cmd = (uint8_t *) cmd_buffer_end;
+ }
+
+ *command_buffer_ptr = cmd;
+ *pixel_start_ptr = pixel;
+ *device_address_ptr = dev_addr;
+
+ return;
+}
+
+/*
+ * There are 3 copies of every pixel: The front buffer that the fbdev
+ * client renders to, the actual framebuffer across the USB bus in hardware
+ * (that we can only write to, slowly, and can never read), and (optionally)
+ * our shadow copy that tracks what's been sent to that hardware buffer.
+ */
+int udl_render_hline(struct drm_device *dev, int bpp, struct urb **urb_ptr,
+ const char *front, char **urb_buf_ptr,
+ u32 byte_offset, u32 device_byte_offset,
+ u32 byte_width,
+ int *ident_ptr, int *sent_ptr)
+{
+ const u8 *line_start, *line_end, *next_pixel;
+ u32 base16 = 0 + (device_byte_offset / bpp) * 2;
+ struct urb *urb = *urb_ptr;
+ u8 *cmd = *urb_buf_ptr;
+ u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
+
+ BUG_ON(!(bpp == 2 || bpp == 4));
+
+ line_start = (u8 *) (front + byte_offset);
+ next_pixel = line_start;
+ line_end = next_pixel + byte_width;
+
+ while (next_pixel < line_end) {
+
+ udl_compress_hline16(&next_pixel,
+ line_end, &base16,
+ (u8 **) &cmd, (u8 *) cmd_end, bpp);
+
+ if (cmd >= cmd_end) {
+ int len = cmd - (u8 *) urb->transfer_buffer;
+ if (udl_submit_urb(dev, urb, len))
+ return 1; /* lost pixels is set */
+ *sent_ptr += len;
+ urb = udl_get_urb(dev);
+ if (!urb)
+ return 1; /* lost_pixels is set */
+ *urb_ptr = urb;
+ cmd = urb->transfer_buffer;
+ cmd_end = &cmd[urb->transfer_buffer_length];
+ }
+ }
+
+ *urb_buf_ptr = cmd;
+
+ return 0;
+}
+
Code Review / kvmfornfv.git / blobdiff