[igt-dev] [PATCH i-g-t 3/6] tools/dpcd_reg: Unify file handling.

[Rodrigo Vivi]

Besides removing few code duplication this will
allow us to read multiple regs without having
to keep closing and opening the file for every
read.

Cc: Tarun Vyas <tarun.vyas at intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 tools/dpcd_reg.c | 98 +++++++++++++++++++++++++++---------------------
 1 file changed, 55 insertions(+), 43 deletions(-)

diff --git a/tools/dpcd_reg.c b/tools/dpcd_reg.c
index d139007c..09da4109 100644
--- a/tools/dpcd_reg.c
+++ b/tools/dpcd_reg.c
@@ -53,61 +53,56 @@ static void print_usage(char *tool, int help)
 	exit((help == 1)? EXIT_SUCCESS : EXIT_FAILURE);
 }
 
-static int dpcd_read(char *device, const uint32_t offset, size_t count)
+static int dpcd_read(int fd, const uint32_t offset, size_t count)
 {
-	int fd, ret, i;
+	int ret, i;
 	void *buf = malloc(sizeof(uint8_t) * count);
 
+	ret = lseek(fd, offset, SEEK_SET);
+	if (ret < 0) {
+		igt_warn("lseek to %04x failed!\n", offset);
+		return ret;
+	}
+
 	if (NULL != buf)
 		memset(buf, 0, sizeof(uint8_t) * count);
 	else {
 		igt_warn("Can't allocate read buffer\n");
-		return EXIT_FAILURE;
+		return -1;
 	}
 
-	fd = open(device, O_RDONLY);
-	if (fd > 0) {
-		ret = pread(fd, buf, count, offset);
-		close(fd);
-		if (ret != count) {
-			igt_warn("Failed to read from %s aux device - error %s\n", device, strerror(errno));
-			ret = EXIT_FAILURE;
-			goto out;
-		}
-
-		igt_info("%04x:", offset);
-		for (i = 0; i < count; i++)
-			igt_info(" %02x", *(((uint8_t *)(buf)) + i));
-		igt_info("\n");
-	}
-	else {
-		igt_warn("Failed to open %s aux device - error: %s\n", device, strerror(errno));
-		ret = EXIT_FAILURE;
+	ret = read(fd, buf, count);
+	if (ret != count) {
+		igt_warn("Failed to read - error %s\n", strerror(errno));
+		goto out;
 	}
+
+	igt_info("%04x:", offset);
+	for (i = 0; i < count; i++)
+		igt_info(" %02x", *(((uint8_t *)(buf)) + i));
+	igt_info("\n");
+
 out:
 	free(buf);
 	return ret;
 }
 
-static int dpcd_write(char *device, const uint32_t offset, const uint8_t *val)
+static int dpcd_write(int fd, const uint32_t offset, const uint8_t *val)
 {
-	int fd, ret;
-
-	fd = open(device, O_RDWR);
-	if (fd > 0) {
-		ret = pwrite(fd, (const void *)val, sizeof(uint8_t), offset);
-		close(fd);
-		if (ret < 0) {
-			igt_warn("Failed to write to %s aux device - error %s\n", device, strerror(errno));
-			ret = EXIT_FAILURE;
-			goto out;
-		}
-		ret = dpcd_read(device, offset, sizeof(uint8_t));
+	int ret;
+
+	ret = lseek(fd, offset, SEEK_SET);
+	if (ret < 0) {
+		igt_warn("lseek to %04x failed!\n", offset);
+		return ret;
 	}
-	else {
-		igt_warn("Failed to open %s aux device - error: %s\n", device, strerror(errno));
-		ret = EXIT_FAILURE;
+
+	ret = write(fd, (const void *)val, sizeof(uint8_t));
+	if (ret < 0) {
+		igt_warn("Failed to write - error %s\n", strerror(errno));
+		goto out;
 	}
+	ret = dpcd_read(fd, offset, sizeof(uint8_t));
 out:
 	return ret;
 }
@@ -115,10 +110,11 @@ out:
 int main(int argc, char **argv)
 {
 	char dev_name[20];
-	int ret, devid, help_flg;
+	int fd, ret, devid, help_flg;
 	uint32_t offset;
 	uint8_t val;
 	size_t count;
+	int file_op = O_RDONLY;
 
 	enum command {
 		INV = -1,
@@ -157,11 +153,12 @@ int main(int argc, char **argv)
 			break;
 		/* Command parsing */
 		case 1:
-			if (strcmp(optarg, "read") == 0)
+			if (strcmp(optarg, "read") == 0) {
 				cmd = READ;
-			else if (strcmp(optarg, "write") == 0)
+			} else if (strcmp(optarg, "write") == 0) {
 				cmd = WRITE;
-			break;
+				file_op = O_RDWR;
+			} break;
 		case ':':
 			igt_warn("The -%c option of %s requires an argument\n",
 				 optopt, argv[0]);
@@ -185,20 +182,33 @@ int main(int argc, char **argv)
 	memset(dev_name, '\0', 20);
 	snprintf(dev_name, sizeof(aux_dev) + 2, "%s%d", aux_dev, devid);
 
+	fd = open(dev_name, file_op);
+	if (fd < 0) {
+		igt_warn("Failed to open %s aux device - error: %s\n", dev_name,
+			 strerror(errno));
+		return EXIT_FAILURE;
+	}
+
 	switch (cmd) {
 	case READ:
 		if (count == INVALID) {
 			igt_warn("Please specify the count in bytes\n");
 			print_usage(argv[0], 0);
 		}
-		ret = dpcd_read(dev_name, offset, count);
+		ret = dpcd_read(fd, offset, count);
+		if (ret != count)
+			igt_warn("Failed to read from %s aux device\n",
+				 dev_name);
 		break;
 	case WRITE:
 		if (val == INVALID) {
 			igt_warn("Write value is missing\n");
 			print_usage(argv[0], 0);
 		}
-		ret = dpcd_write(dev_name, offset, &val);
+		ret = dpcd_write(fd, offset, &val);
+		if (ret < 0)
+			igt_warn("Failed to write to %s aux device\n",
+				 dev_name);
 		break;
 	case INV:
 	default:
@@ -206,5 +216,7 @@ int main(int argc, char **argv)
 		print_usage(argv[0], 0);
 	}
 
+	close(fd);
+
 	return ret;
 }
-- 
2.17.1