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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2012 Red Hat4 * based in parts on udlfb.c:5 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>6 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>7 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>8 */9 10#include <linux/unaligned.h>11 12#include "udl_drv.h"13#include "udl_proto.h"14 15#define MAX_CMD_PIXELS 25516 17#define RLX_HEADER_BYTES 718#define MIN_RLX_PIX_BYTES 419#define MIN_RLX_CMD_BYTES (RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)20 21#define RLE_HEADER_BYTES 622#define MIN_RLE_PIX_BYTES 323#define MIN_RLE_CMD_BYTES (RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)24 25#define RAW_HEADER_BYTES 626#define MIN_RAW_PIX_BYTES 227#define MIN_RAW_CMD_BYTES (RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)28 29static inline u16 pixel32_to_be16(const uint32_t pixel)30{31 return (((pixel >> 3) & 0x001f) |32 ((pixel >> 5) & 0x07e0) |33 ((pixel >> 8) & 0xf800));34}35 36static inline u16 get_pixel_val16(const uint8_t *pixel, int log_bpp)37{38 u16 pixel_val16;39 if (log_bpp == 1)40 pixel_val16 = *(const uint16_t *)pixel;41 else42 pixel_val16 = pixel32_to_be16(*(const uint32_t *)pixel);43 return pixel_val16;44}45 46/*47 * Render a command stream for an encoded horizontal line segment of pixels.48 *49 * A command buffer holds several commands.50 * It always begins with a fresh command header51 * (the protocol doesn't require this, but we enforce it to allow52 * multiple buffers to be potentially encoded and sent in parallel).53 * A single command encodes one contiguous horizontal line of pixels54 *55 * The function relies on the client to do all allocation, so that56 * rendering can be done directly to output buffers (e.g. USB URBs).57 * The function fills the supplied command buffer, providing information58 * on where it left off, so the client may call in again with additional59 * buffers if the line will take several buffers to complete.60 *61 * A single command can transmit a maximum of 256 pixels,62 * regardless of the compression ratio (protocol design limit).63 * To the hardware, 0 for a size byte means 25664 *65 * Rather than 256 pixel commands which are either rl or raw encoded,66 * the rlx command simply assumes alternating raw and rl spans within one cmd.67 * This has a slightly larger header overhead, but produces more even results.68 * It also processes all data (read and write) in a single pass.69 * Performance benchmarks of common cases show it having just slightly better70 * compression than 256 pixel raw or rle commands, with similar CPU consumpion.71 * But for very rl friendly data, will compress not quite as well.72 */73static void udl_compress_hline16(74 const u8 **pixel_start_ptr,75 const u8 *const pixel_end,76 uint32_t *device_address_ptr,77 uint8_t **command_buffer_ptr,78 const uint8_t *const cmd_buffer_end, int log_bpp)79{80 const int bpp = 1 << log_bpp;81 const u8 *pixel = *pixel_start_ptr;82 uint32_t dev_addr = *device_address_ptr;83 uint8_t *cmd = *command_buffer_ptr;84 85 while ((pixel_end > pixel) &&86 (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {87 uint8_t *raw_pixels_count_byte = NULL;88 uint8_t *cmd_pixels_count_byte = NULL;89 const u8 *raw_pixel_start = NULL;90 const u8 *cmd_pixel_start, *cmd_pixel_end = NULL;91 uint16_t pixel_val16;92 93 *cmd++ = UDL_MSG_BULK;94 *cmd++ = UDL_CMD_WRITERLX16;95 *cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);96 *cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);97 *cmd++ = (uint8_t) ((dev_addr) & 0xFF);98 99 cmd_pixels_count_byte = cmd++; /* we'll know this later */100 cmd_pixel_start = pixel;101 102 raw_pixels_count_byte = cmd++; /* we'll know this later */103 raw_pixel_start = pixel;104 105 cmd_pixel_end = pixel + (min3(MAX_CMD_PIXELS + 1UL,106 (unsigned long)(pixel_end - pixel) >> log_bpp,107 (unsigned long)(cmd_buffer_end - 1 - cmd) / 2) << log_bpp);108 109 pixel_val16 = get_pixel_val16(pixel, log_bpp);110 111 while (pixel < cmd_pixel_end) {112 const u8 *const start = pixel;113 const uint16_t repeating_pixel_val16 = pixel_val16;114 115 put_unaligned_be16(pixel_val16, cmd);116 117 cmd += 2;118 pixel += bpp;119 120 while (pixel < cmd_pixel_end) {121 pixel_val16 = get_pixel_val16(pixel, log_bpp);122 if (pixel_val16 != repeating_pixel_val16)123 break;124 pixel += bpp;125 }126 127 if (unlikely(pixel > start + bpp)) {128 /* go back and fill in raw pixel count */129 *raw_pixels_count_byte = (((start -130 raw_pixel_start) >> log_bpp) + 1) & 0xFF;131 132 /* immediately after raw data is repeat byte */133 *cmd++ = (((pixel - start) >> log_bpp) - 1) & 0xFF;134 135 /* Then start another raw pixel span */136 raw_pixel_start = pixel;137 raw_pixels_count_byte = cmd++;138 }139 }140 141 if (pixel > raw_pixel_start) {142 /* finalize last RAW span */143 *raw_pixels_count_byte = ((pixel - raw_pixel_start) >> log_bpp) & 0xFF;144 } else {145 /* undo unused byte */146 cmd--;147 }148 149 *cmd_pixels_count_byte = ((pixel - cmd_pixel_start) >> log_bpp) & 0xFF;150 dev_addr += ((pixel - cmd_pixel_start) >> log_bpp) * 2;151 }152 153 if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {154 /* Fill leftover bytes with no-ops */155 if (cmd_buffer_end > cmd)156 memset(cmd, UDL_MSG_BULK, cmd_buffer_end - cmd);157 cmd = (uint8_t *) cmd_buffer_end;158 }159 160 *command_buffer_ptr = cmd;161 *pixel_start_ptr = pixel;162 *device_address_ptr = dev_addr;163 164 return;165}166 167/*168 * There are 3 copies of every pixel: The front buffer that the fbdev169 * client renders to, the actual framebuffer across the USB bus in hardware170 * (that we can only write to, slowly, and can never read), and (optionally)171 * our shadow copy that tracks what's been sent to that hardware buffer.172 */173int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr,174 const char *front, char **urb_buf_ptr,175 u32 byte_offset, u32 device_byte_offset,176 u32 byte_width)177{178 const u8 *line_start, *line_end, *next_pixel;179 u32 base16 = 0 + (device_byte_offset >> log_bpp) * 2;180 struct urb *urb = *urb_ptr;181 u8 *cmd = *urb_buf_ptr;182 u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;183 184 if (WARN_ON(!(log_bpp == 1 || log_bpp == 2))) {185 /* need to finish URB at error from this function */186 udl_urb_completion(urb);187 return -EINVAL;188 }189 190 line_start = (u8 *) (front + byte_offset);191 next_pixel = line_start;192 line_end = next_pixel + byte_width;193 194 while (next_pixel < line_end) {195 196 udl_compress_hline16(&next_pixel,197 line_end, &base16,198 (u8 **) &cmd, (u8 *) cmd_end, log_bpp);199 200 if (cmd >= cmd_end) {201 int len = cmd - (u8 *) urb->transfer_buffer;202 int ret = udl_submit_urb(dev, urb, len);203 if (ret)204 return ret;205 urb = udl_get_urb(dev);206 if (!urb)207 return -EAGAIN;208 *urb_ptr = urb;209 cmd = urb->transfer_buffer;210 cmd_end = &cmd[urb->transfer_buffer_length];211 }212 }213 214 *urb_buf_ptr = cmd;215 216 return 0;217}218