1 files changed, 253 insertions, 0 deletions

diff --git a/drivers/gpu/drm/udl/udl_transfer.c b/drivers/gpu/drm/udl/udl_transfer.c
new file mode 100644
index 000000000000..b9320e2608dd
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_transfer.c
@@ -0,0 +1,253 @@
+/*
+ * 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 "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_be16p(const uint8_t *pixel)
+{
+        uint32_t pix = *(uint32_t *)pixel;
+        u16 retval;
+
+        retval =  (((pix >> 3) & 0x001f) |
+                   ((pix >> 5) & 0x07e0) |
+                   ((pix >> 8) & 0xf800));
+        return retval;
+}
+
+/*
+ * 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 = 0;
+                uint8_t *cmd_pixels_count_byte = 0;
+                const u8 *raw_pixel_start = 0;
+                const u8 *cmd_pixel_start, *cmd_pixel_end = 0;
+
+                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);
+
+                while (pixel < cmd_pixel_end) {
+                        const u8 * const repeating_pixel = pixel;
+
+                        if (bpp == 2)
+                                *(uint16_t *)cmd = cpu_to_be16p((uint16_t *)pixel);
+                        else if (bpp == 4)
+                                *(uint16_t *)cmd = cpu_to_be16(pixel32_to_be16p(pixel));
+
+                        cmd += 2;
+                        pixel += bpp;
+
+                        if (unlikely((pixel < cmd_pixel_end) &&
+                                     (!memcmp(pixel, repeating_pixel, bpp)))) {
+                                /* go back and fill in raw pixel count */
+                                *raw_pixels_count_byte = (((repeating_pixel -
+                                                raw_pixel_start) / bpp) + 1) & 0xFF;
+
+                                while ((pixel < cmd_pixel_end)
+                                       && (!memcmp(pixel, repeating_pixel, bpp))) {
+                                        pixel += bpp;
+                                }
+
+                                /* immediately after raw data is repeat byte */
+                                *cmd++ = (((pixel - repeating_pixel) / 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 byte_width,
+                     int *ident_ptr, int *sent_ptr)
+{
+        const u8 *line_start, *line_end, *next_pixel;
+        u32 base16 = 0 + (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;
+
+        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;
+}
+