3 files changed, 116 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1d5825c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.o
+intelgpio
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..66f60bb
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,25 @@
+## SPDX-License-Identifier: GPL-2.0-only
+
+CC = gcc
+CFLAGS = -O2 -Wall -Wextra -Werror
+PROGRAM = intelgpio
+INSTALL = /usr/bin/env install
+PREFIX	= /usr/local
+
+all: $(PROGRAM)
+
+$(PROGRAM): intelgpio.o
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
+install: $(PROGRAM)
+	$(INSTALL) $(PROGRAM) $(PREFIX)/sbin
+
+clean:
+	rm -f *.o $(PROGRAM)
+
+distclean: clean
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $^ -I. -o $@
+
+.PHONY: all install clean distclean
diff --git a/intelgpio.c b/intelgpio.c
new file mode 100644
index 0000000..0f4011d
--- /dev/null
+++ b/intelgpio.c
@@ -0,0 +1,89 @@
+#include <stdio.h>
+#include <getopt.h>
+#include <sys/io.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+
+#define GPIO_BASE	0x48
+#define GP_LVL		0x0c
+#define GP_LVL2		0x38
+#define GP_LVL3		0x48
+#define MAX_GPIO_NUMBER	75
+#define LPC_DEV_CONFIG	"/sys/bus/pci/devices/0000:00:1f.0/config"
+
+void usage(const char *name)
+{
+	printf("usage: %s OPTIONS\n", name);
+	printf("Options:\n"
+	       "	-h: Print this help\n"
+	       "	-n: GPIO pin number\n");
+}
+
+int get_gpio(int base, int num)
+{
+	static const int gpio_reg_offsets[] = {GP_LVL, GP_LVL2, GP_LVL3};
+	int index, bit;
+
+	index = num / 32;
+	bit = num % 32;
+
+	return (inl(base + gpio_reg_offsets[index]) >> bit) & 1;
+}
+
+int main(int argc, char *argv[])
+{
+	int c;
+	int num = -1;
+	uint16_t base;
+	while ((c = getopt(argc, argv, "hn:")) != -1) {
+		switch (c) {
+		case 'h':
+			usage(argv[0]);
+			return 0;
+		case 'n':
+			num = strtoul(optarg, NULL, 10);
+			if (num > MAX_GPIO_NUMBER) {
+				fprintf(stderr, "error: invalid number\n");
+				return 1;
+			}
+			break;
+		case '?':
+			return -1;
+		}
+	}
+
+	if (num == -1) {
+		usage(argv[0]);
+		return 0;
+	}
+
+	if (geteuid() != 0) {
+		fprintf(stderr, "error: you must be root\n");
+		return 1;
+	}
+
+	FILE *f = fopen(LPC_DEV_CONFIG, "r");
+	if (!f) {
+		fprintf(stderr, "failed to open %s: %s\n", LPC_DEV_CONFIG, strerror(errno));
+		return 1;
+	}
+
+	fseek(f, GPIO_BASE, SEEK_SET);
+	fread(&base, 2, 1, f);
+	fclose(f);
+
+	base &= 0xfffe;
+
+	if (ioperm(base, 0x100, 1)) {
+		fprintf(stderr, "ioperm: %s\n", strerror(errno));
+		exit(1);
+	}
+
+	int val = get_gpio(base, num);
+	printf("%d\n", val);
+
+	return 0;
+}
+\ No newline at end of file