Re: [libgpiod PATCH 4/7] tools: gpioget: Add by-name support

[Zev Weiss <zweiss@xxxxxxxxxxx>]

On Wed, Feb 02, 2022 at 08:21:31PM PST, Joel Stanley wrote:
>Allow users to get the values of gpios by passing the gpio name. The
>gpipchip is not specified, instead it is discovered using the same
>method as gpiofind.
>
> $ gpioget --by-name switch-state
> 1
>
> $ gpioget --by-name led-fault led-identify led-attention
> 1 0 1
>
>Signed-off-by: Joel Stanley <joel@xxxxxxxxx>
>---
> tools/gpioget.c | 57 +++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 41 insertions(+), 16 deletions(-)
>
>diff --git a/tools/gpioget.c b/tools/gpioget.c
>index 51cecb6a18a9..9d2c82b0d64b 100644
>--- a/tools/gpioget.c
>+++ b/tools/gpioget.c
>@@ -15,15 +15,18 @@ static const struct option longopts[] = {
> 	{ "active-low",	no_argument,		NULL,	'l' },
> 	{ "dir-as-is",	no_argument,		NULL,	'n' },
> 	{ "bias",	required_argument,	NULL,	'B' },
>+	{ "by-name",	no_argument,		NULL,	'N' },
> 	{ GETOPT_NULL_LONGOPT },
> };
>
>-static const char *const shortopts = "+hvlnB:";
>+static const char *const shortopts = "+hvlnB:N";
>
> static void print_help(void)
> {
> 	printf("Usage: %s [OPTIONS] <chip name/number> <offset 1> <offset 2> ...\n",
> 	       get_progname());
>+	printf("       %s [OPTIONS] -L <line name1> <line name2> ...\n",

I'm guessing this -L was supposed to be -N?

>+	       get_progname());
> 	printf("\n");
> 	printf("Read line value(s) from a GPIO chip\n");
> 	printf("\n");
>@@ -34,6 +37,7 @@ static void print_help(void)
> 	printf("  -n, --dir-as-is:\tdon't force-reconfigure line direction\n");
> 	printf("  -B, --bias=[as-is|disable|pull-down|pull-up] (defaults to 'as-is'):\n");
> 	printf("		set the line bias\n");
>+	printf("  -N, --by-name:\tget line by name. All lines must be from the same gpiochip\n");
> 	printf("\n");
> 	print_bias_help();
> }
>@@ -46,7 +50,8 @@ int main(int argc, char **argv)
> 	unsigned int *offsets, i, num_lines;
> 	struct gpiod_line_bulk *lines;
> 	struct gpiod_chip *chip;
>-	char *device, *end;
>+	bool by_name = false;
>+	char *end;
>
> 	for (;;) {
> 		optc = getopt_long(argc, argv, shortopts, longopts, &opti);
>@@ -69,6 +74,9 @@ int main(int argc, char **argv)
> 		case 'B':
> 			flags |= bias_flags(optarg);
> 			break;
>+		case 'N':
>+			by_name = true;
>+			break;
> 		case '?':
> 			die("try %s --help", get_progname());
> 		default:
>@@ -79,30 +87,47 @@ int main(int argc, char **argv)
> 	argc -= optind;
> 	argv += optind;
>
>-	if (argc < 1)
>-		die("gpiochip must be specified");
>+	if (by_name) {
>+		if (argc < 1)
>+			die("at least one line name must be specified");
>+
>+		/* line0 line1 ... lineN */
>+		num_lines = argc;
>
>-	if (argc < 2)
>-		die("at least one GPIO line offset must be specified");
>+		chip = chip_by_line_name(argv[0]);
>+		if (!chip)
>+			die("unable to find gpiochip");

The next patch has a slightly more informative corresponding error
message for gpioset; might be nice to make this match that.

>+	} else {
>+		/* gpiochip offset0 offset1 ... offsetN */
>+		if (argc < 1)
>+			die("gpiochip must be specified");
>
>-	device = argv[0];
>-	num_lines = argc - 1;
>+		if (argc < 2)
>+			die("at least one GPIO line offset must be specified");
>+
>+		chip = chip_open_lookup(argv[0]);
>+		if (!chip)
>+			die_perror("unable to open %s", argv[0]);
>+
>+		argv++;
>+		num_lines = argc - 1;
>+	}
>
> 	values = malloc(sizeof(*values) * num_lines);
> 	offsets = malloc(sizeof(*offsets) * num_lines);
> 	if (!values || !offsets)
> 		die("out of memory");
>
>-	for (i = 0; i < num_lines; i++) {
>-		offsets[i] = strtoul(argv[i + 1], &end, 10);
>-		if (*end != '\0' || offsets[i] > INT_MAX)
>-			die("invalid GPIO offset: %s", argv[i + 1]);
>+	if (by_name) {
>+		line_names_to_offsets(chip, argv, offsets, NULL, num_lines);
>+	} else {
>+		for (i = 0; i < num_lines; i++) {
>+			offsets[i] = strtoul(argv[i], &end, 10);
>+			if (*end != '\0' || offsets[i] > INT_MAX)
>+				die("invalid GPIO offset: %s", argv[i]);
>+		}
> 	}
>
>-	chip = chip_open_lookup(device);
>-	if (!chip)
>-		die_perror("unable to open %s", device);
>-
> 	lines = gpiod_chip_get_lines(chip, offsets, num_lines);
> 	if (!lines)
> 		die_perror("unable to retrieve GPIO lines from chip");
>-- 
>2.34.1
>