From: Ben Harris <bjh21@bjh21.me.uk>
Date: Thu, 22 Nov 2018 23:46:46 +0000 (+0000)
Subject: Add support for operating GPIO lines through libgpiod.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~bjharris/git?a=commitdiff_plain;h=568bbbe5f3160923617d3b1f4bf2fdd36f9a0857;p=clunk.git

Add support for operating GPIO lines through libgpiod.

Untested, since the Raspberry Pi at my disposal doesn't yet have
libgpiod.
---

diff --git a/Makefile b/Makefile
index 7d4839e..387c3ab 100644
--- a/Makefile
+++ b/Makefile
@@ -1 +1,3 @@
-LDLIBS=-lrt
+all: clunk
+LDLIBS+=-lrt $$(pkg-config --libs libgpiod)
+CFLAGS+=$$(pkg-config --cflags libgpiod)
diff --git a/clunk.c b/clunk.c
index c6b847a..1879e70 100644
--- a/clunk.c
+++ b/clunk.c
@@ -1,6 +1,7 @@
 #include <err.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <gpiod.h>
 #include <signal.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -53,6 +54,19 @@ dummy_out(bool state)
 		fflush(stdout);
 	}
 }
+
+static struct gpiod_line *libgpiod_line;
+
+static void
+libgpiod_out(bool state)
+{
+
+	if (gpiod_line_set_value(libgpiod_line, state) == -1)
+		err(1, "gpiod_line_set_value");
+}
+
+static void (*outfn)(bool) = &dummy_out;
+
 static void
 record_tick()
 {
@@ -88,12 +102,12 @@ pulse()
 
 	if (sigprocmask(SIG_BLOCK, &signals_to_block, &saved_mask) != 0)
 		err(1, "sigprocmask(block)");
-	dummy_out(true);
+	(*outfn)(true);
 	record_tick();
 	errno = clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL);
 	if (errno != 0)
 		err(1, "clock_nanosleep");
-	dummy_out(false);
+	(*outfn)(false);
 	if (sigprocmask(SIG_SETMASK, &saved_mask, NULL) != 0)
 		err(1, "sigprocmask(restore)");
 }
@@ -124,6 +138,17 @@ init_statefile(char const *statefilename)
 	}
 }
 
+static void
+init_libgpiod(char const *gpio_name)
+{
+
+	libgpiod_line = gpiod_line_find(gpio_name);
+	if (libgpiod_line == NULL)
+		err(1, "GPIO line '%s'", gpio_name);
+	if (gpiod_line_request_output(libgpiod_line, "clunk", false) == -1)
+		err(1, "requesting '%s'", gpio_name);
+}
+
 static void
 alrm_handler(int signo)
 {
@@ -160,7 +185,7 @@ init(int argc, char **argv)
 	if (localtime_r(&ts.tv_sec, &displayed) == NULL)
 		err(1, "localtime_r");
 	displayed.tm_sec = (displayed.tm_sec >= 30) ? 30 : 0;
-	while ((opt = getopt(argc, argv, "f:s:")) != -1) {
+	while ((opt = getopt(argc, argv, "f:g:s:")) != -1) {
 		switch (opt) {
 		case 'f':
 			statefile = optarg;
@@ -168,6 +193,9 @@ init(int argc, char **argv)
 		case 's':
 			statestr = optarg;
 			break;
+		case 'g':
+			init_libgpiod(optarg);
+			break;
 		}
 	}
 	if (statefile != NULL)