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

* [igt-dev] [PATCH i-g-t v3] tools: Add a simple tool to read/write/decode dpcd registers
@ 2018-09-14 23:57 Tarun Vyas
  2018-09-15  0:24 ` [igt-dev] ✓ Fi.CI.BAT: success for tools: Add a simple tool to read/write/decode dpcd registers (rev3) Patchwork
                   ` (3 more replies)
  0 siblings, 4 replies; 8+ messages in thread
From: Tarun Vyas @ 2018-09-14 23:57 UTC (permalink / raw)
  To: igt-dev; +Cc: dhinakaran.pandiyan, rodrigo.vivi

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

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