[igt-dev] [PATCH i-g-t v3] tools: Add a simple tool to read/write/decode dpcd registers

Tarun Vyas
2018-09-14T23:57:36Z

This tool serves as a wrapper around the constructs provided by the
drm_dpcd_aux_dev kernel module by working on the /dev/drm_dp_aux[n]
devices created by the kernel module.
It supports reading and writing dpcd registers on the connected aux
channels.
In the follow-up patch, support for decoding these registers will be
added to facilate debugging panel related issues.

v2: (Fixes by Rodrigo but no functional changes yet):
- Indentations, Typo, Missed spaces
- Removing mentioning to decode and spec that is not implemented yet.
- Add Makefile.sources back
- Missed s/printf/igt_warn

v3:
- Addres DK's review comments from v2 above.
- Squash Rodrigo's file handling unification patch.
- Make count, offset and device id optional.

Suggested-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: Tarun Vyas <tarun.vyas@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
tools/Makefile.sources | 1 +
tools/dpcd_reg.c | 213 +++++++++++++++++++++++++++++++++++++++++++++++++
tools/meson.build | 1 +
3 files changed, 215 insertions(+)
create mode 100644 tools/dpcd_reg.c

diff --git a/tools/Makefile.sources b/tools/Makefile.sources
index abd23a0f..50706f41 100644
--- a/tools/Makefile.sources
+++ b/tools/Makefile.sources
@@ -7,6 +7,7 @@ noinst_PROGRAMS = \

tools_prog_lists = \
igt_stats \
+ dpcd_reg \
intel_audio_dump \
intel_reg \
intel_backlight \
diff --git a/tools/dpcd_reg.c b/tools/dpcd_reg.c
new file mode 100644
index 00000000..cd9fed4f
--- /dev/null
+++ b/tools/dpcd_reg.c
@@ -0,0 +1,213 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * DPCD register read/write tool
+ * This tool wraps around DRM_DP_AUX_DEV module to provide DPCD register read
+ * and write, so CONFIG_DRM_DP_AUX_DEV needs to be set.
+ */
+
+#include "igt_core.h"
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+
+#define MAX_OFFSET 0xf02ff
+
+const char aux_dev[] = "/dev/drm_dp_aux";
+
+static void print_usage(char *tool, int exit_code)
+{
+ printf("DPCD register read and write tool\n\n");
+ printf("This tool requires CONFIG_DRM_DP_AUX_CHARDEV\n"
+ "to be set in the kernel config.\n\n");
+ printf("Usage: %s [OPTION ...] COMMAND\n\n", tool);
+ printf("COMMAND is one of:\n");
+ printf(" read: Read [count] bytes dpcd reg at an offset\n");
+ printf(" write: Write a dpcd reg at an offset\n\n");
+ printf("Options for the above COMMANDS are\n");
+ printf(" --device=DEVID Aux device id, as listed in /dev/drm_dp_aux_dev[n]."
+ "Defaults to 0\n");
+ printf(" --offset=REG_ADDR DPCD register offset in hex. Defaults to 0x00\n");
+ printf(" --count=BYTES For reads, specify number of bytes to be read from"
+ "the offset. Defaults to 1\n");
+ printf(" --val For writes, specify a hex value to be written\n\n");
+
+ printf(" --help: print the usage\n");
+
+ exit(exit_code);
+}
+
+static int dpcd_read(int fd, const uint32_t offset, size_t count)
+{
+ int ret, i;
+ void *buf = calloc(count, sizeof(uint8_t));
+
+ if (!buf) {
+ fprintf(stderr, "Can't allocate read buffer\n");
+ return ENOMEM;
+ }
+
+ ret = pread(fd, buf, count, offset);
+ if (ret != count) {
+ fprintf(stderr, "Failed to read - %s\n", strerror(errno));
+ ret = errno;
+ goto out;
+ } else
+ ret = EXIT_SUCCESS;
+
+ printf("Read %zu byte(s) starting at offset %x\n\n", count, offset);
+ for (i = 0; i < count; i++)
+ printf(" %02x", *(((uint8_t *)(buf)) + i));
+ printf("\n");
+
+out:
+ free(buf);
+ return ret;
+}
+
+static int dpcd_write(int fd, const uint32_t offset, const uint8_t val)
+{
+ int ret;
+
+ ret = pwrite(fd, (const void *)&val, sizeof(uint8_t), offset);
+ if (ret < 0) {
+ fprintf(stderr, "Failed to write - %s\n", strerror(errno));
+ return errno;
+ } else
+ return EXIT_SUCCESS;
+}
+
+int main(int argc, char **argv)
+{
+ char dev_name[20];
+ int ret, devid, fd, vflag = 0;
+ uint32_t offset;
+ uint8_t val;
+ size_t count;
+ int file_op = O_RDONLY;
+
+ enum command {
+ INV = -1,
+ READ = 2,
+ WRITE,
+ } cmd = INV;
+
+ struct option longopts[] = {
+ { "count", required_argument, NULL, 'c' },
+ { "device", required_argument, NULL, 'd' },
+ { "help", no_argument, NULL, 'h' },
+ { "offset", required_argument, NULL, 'o' },
+ { "value", required_argument, &vflag, 'v' },
+ { 0 }
+ };
+
+ devid = 0, count = 1, offset = 0x0;
+
+ while ((ret = getopt_long(argc, argv, "-:c:d:h:o:", longopts, NULL)) != -1) {
+ switch (ret) {
+ case 'c':
+ count = strtoul(optarg, NULL, 10);
+ if (count == ULONG_MAX) {
+ fprintf(stderr, "Count argument too big\n");
+ exit(ERANGE);
+ }
+ break;
+ case 'd':
+ devid = strtoul(optarg, NULL, 10);
+ if (devid == ULONG_MAX) {
+ fprintf(stderr, "Devid argument too big\n");
+ exit(ERANGE);
+ }
+ break;
+ case 'h':
+ print_usage(argv[0], EXIT_SUCCESS);
+ break;
+ case 'o':
+ offset = strtoul(optarg, NULL, 16);
+ if (offset > MAX_OFFSET) {
+ fprintf(stderr, "Offset should be <= 0xf02ff\n");
+ exit(ERANGE);
+ }
+ break;
+ case 0:
+ if (vflag == 'v' && optarg)
+ val = (uint8_t) strtoul(optarg, NULL, 16);
+ break;
+ /* Command parsing */
+ case 1:
+ if (strcmp(optarg, "read") == 0) {
+ cmd = READ;
+ } else if (strcmp(optarg, "write") == 0) {
+ cmd = WRITE;
+ file_op = O_WRONLY;
+ }
+ break;
+ case ':':
+ fprintf(stderr, "The -%c option of %s requires an argument\n",
+ optopt, argv[0]);
+ print_usage(argv[0], EXIT_FAILURE);
+ case '?':
+ default:
+ fprintf(stderr, "%s - option %c is invalid\n", argv[0],
+ optopt);
+ print_usage(argv[0], EXIT_FAILURE);
+ }
+ }
+
+ if ((count + offset) > (MAX_OFFSET + 1)) {
+ fprintf(stderr, "Out of bounds. Count + Offset <= 0xf0300\n");
+ exit(ERANGE);
+ }
+
+ if ((cmd == WRITE) && (vflag != 'v')) {
+ fprintf(stderr, "Write value is missing\n");
+ print_usage(argv[0], EXIT_FAILURE);
+ }
+
+ memset(dev_name, '\0', 20);
+ snprintf(dev_name, strlen(aux_dev) + 3, "%s%d", aux_dev, devid);
+
+ fd = open(dev_name, file_op);
+ if (fd < 0) {
+ fprintf(stderr, "Failed to open %s aux device - error: %s\n", dev_name,
+ strerror(errno));
+ return errno;
+ }
+
+ switch (cmd) {
+ case READ:
+ ret = dpcd_read(fd, offset, count);
+ break;
+ case WRITE:
+ ret = dpcd_write(fd, offset, val);
+ break;
+ case INV:
+ default:
+ fprintf(stderr, "Please specify a command: read/write. See usage\n");
+ close(fd);
+ print_usage(argv[0], EXIT_FAILURE);
+ }
+
+ close(fd);
+
+ return ret;
+}
diff --git a/tools/meson.build b/tools/meson.build
index e4517d66..79f36aa9 100644
--- a/tools/meson.build
+++ b/tools/meson.build
@@ -36,6 +36,7 @@ tools_progs = [
'intel_watermark',
'intel_gem_info',
'intel_gvtg_test',
+ 'dpcd_reg',
]
tool_deps = igt_deps

--
2.14.1