| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * 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> |
| */ |
| |
| #include <linux/unaligned.h> |
| |
| #include "udl_drv.h" |
| #include "udl_proto.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) |
| |
| 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 log_bpp) |
| { |
| u16 pixel_val16; |
| if (log_bpp == 1) |
| pixel_val16 = *(const uint16_t *)pixel; |
| else |
| 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 log_bpp) |
| { |
| const int bpp = 1 << log_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; |
| |
| *cmd++ = UDL_MSG_BULK; |
| *cmd++ = UDL_CMD_WRITERLX16; |
| *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 + (min3(MAX_CMD_PIXELS + 1UL, |
| (unsigned long)(pixel_end - pixel) >> log_bpp, |
| (unsigned long)(cmd_buffer_end - 1 - cmd) / 2) << log_bpp); |
| |
| pixel_val16 = get_pixel_val16(pixel, log_bpp); |
| |
| while (pixel < cmd_pixel_end) { |
| const u8 *const start = pixel; |
| const uint16_t repeating_pixel_val16 = pixel_val16; |
| |
| put_unaligned_be16(pixel_val16, cmd); |
| |
| cmd += 2; |
| pixel += bpp; |
| |
| while (pixel < cmd_pixel_end) { |
| pixel_val16 = get_pixel_val16(pixel, log_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) >> log_bpp) + 1) & 0xFF; |
| |
| /* immediately after raw data is repeat byte */ |
| *cmd++ = (((pixel - start) >> log_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) >> log_bpp) & 0xFF; |
| } else { |
| /* undo unused byte */ |
| cmd--; |
| } |
| |
| *cmd_pixels_count_byte = ((pixel - cmd_pixel_start) >> log_bpp) & 0xFF; |
| dev_addr += ((pixel - cmd_pixel_start) >> log_bpp) * 2; |
| } |
| |
| if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) { |
| /* Fill leftover bytes with no-ops */ |
| if (cmd_buffer_end > cmd) |
| memset(cmd, UDL_MSG_BULK, 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 log_bpp, struct urb **urb_ptr, |
| const char *front, char **urb_buf_ptr, |
| u32 byte_offset, u32 device_byte_offset, |
| u32 byte_width) |
| { |
| const u8 *line_start, *line_end, *next_pixel; |
| u32 base16 = 0 + (device_byte_offset >> log_bpp) * 2; |
| struct urb *urb = *urb_ptr; |
| u8 *cmd = *urb_buf_ptr; |
| u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length; |
| |
| if (WARN_ON(!(log_bpp == 1 || log_bpp == 2))) { |
| /* need to finish URB at error from this function */ |
| udl_urb_completion(urb); |
| return -EINVAL; |
| } |
| |
| 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, log_bpp); |
| |
| if (cmd >= cmd_end) { |
| int len = cmd - (u8 *) urb->transfer_buffer; |
| int ret = udl_submit_urb(dev, urb, len); |
| if (ret) |
| return ret; |
| urb = udl_get_urb(dev); |
| if (!urb) |
| return -EAGAIN; |
| *urb_ptr = urb; |
| cmd = urb->transfer_buffer; |
| cmd_end = &cmd[urb->transfer_buffer_length]; |
| } |
| } |
| |
| *urb_buf_ptr = cmd; |
| |
| return 0; |
| } |