initial import

3 files changed, 163 insertions, 0 deletions

diff --git a/Makefile b/Makefile
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+++ b/Makefile
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+CFLAGS?=-Wall -Os -ggdb
+
+all: hidptp
+
+clean:
+	rm -f hidptp *.o
diff --git a/README b/README
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+++ b/README
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+hidptp -- a quick and dirty utility to debug Precision Touchpad (PTP) devices
+
+Build hidptp by typing "make".
+
+Use the utility as follows:
+
+./hidptp <hiddev device node> <enable or disable PTP mode>
+
+For example,
+./hidptp /dev/usb/hiddev0 0
+
+will disable PTP mode in device hiddev0. It is hard to know which physical device
+"hiddev0" represents, but on my Surface Pro 2 it is the Type Cover v2. You may
+need to test hiddev1, hiddev2, etc.
+
+The utility will print the name of the device (so for a Type/Touch Cover 1/2 it
+should be "MICROSOFT SAM"), and then enable or disable PTP mode as requested.
+
+Current Linux versions can't work when the touchpad is configured in PTP mode.
+So in most scenarios you want to disable PTP mode.
+
+As an additional feature the tool will start listening and dumping events from
+the selected device. Stop with Ctrl+C.
diff --git a/hidptp.c b/hidptp.c
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+++ b/hidptp.c
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+#include <stdlib.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <assert.h>
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <fcntl.h>
+
+#include <linux/ioctl.h>
+#include <linux/hiddev.h>
+
+static int devfd;
+
+static char *get_device_name()
+{
+	static char buf[1024];
+
+	if (ioctl(devfd, HIDIOCGNAME(sizeof(buf)), buf) >= 0) {
+		return buf;
+	}
+
+	return NULL;
+}
+
+static void process_event(struct hiddev_usage_ref *ev)
+{
+	printf("0x%x (0x%x): %d\n", ev->usage_code, ev->report_id, ev->value);
+}
+
+static bool send_report(unsigned int report_type, unsigned int report_id)
+{
+	struct hiddev_report_info rinfo;
+	rinfo.report_type = report_type;
+	rinfo.report_id = report_id;
+	rinfo.num_fields = 0;
+
+	if (ioctl(devfd, HIDIOCSREPORT, &rinfo) < 0) {
+		perror("HIDIOCSREPORT");
+		return false;
+	}
+
+	printf("Report 0x%x sent\n", rinfo.report_id);
+
+	return true;
+}
+
+static __s32 read_usage(unsigned int report_type, unsigned int usage_code)
+{
+	struct hiddev_usage_ref uref;
+	uref.report_type = report_type;
+	uref.report_id = HID_REPORT_ID_UNKNOWN;
+	uref.usage_code = usage_code;
+
+	if (ioctl(devfd, HIDIOCGUSAGE, &uref) < 0) {
+		perror("HIDIOCGUSAGE");
+		return -1;
+	}
+
+	printf("0x%x: %d\n", uref.usage_code, uref.value);
+
+	return uref.value;
+}
+
+static void write_usage(unsigned int report_type, unsigned int usage_code, __s32 value)
+{
+	struct hiddev_usage_ref uref;
+	uref.report_type = report_type;
+	uref.report_id = HID_REPORT_ID_UNKNOWN;
+	uref.usage_code = usage_code;
+
+	if (ioctl(devfd, HIDIOCGUSAGE, &uref) < 0) {
+		perror("HIDIOCGUSAGE");
+		return;
+	}
+
+	uref.value = value;
+	if (ioctl(devfd, HIDIOCSUSAGE, &uref) < 0)
+	{
+		perror("HIDIOCSUSAGE");
+		return;
+	}
+
+	printf("0x%x := %d\n", uref.usage_code, uref.value);
+
+	send_report(uref.report_type, uref.report_id);
+}
+
+int main(int argc, const char *argv[])
+{
+	if (argc != 3) {
+		fprintf(stderr, "Usage: %s <device> <0|1>\n", argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	const char *device = argv[1];
+	const bool enable_ptp = strtol(argv[2], NULL, 10);
+
+	printf("Opening %s...\n", device);
+	devfd = open(device, O_RDONLY);
+
+	if (devfd == -1) {
+		perror("Could not open device");
+		return EXIT_FAILURE;
+	}
+
+	printf("Found '%s'\n", get_device_name());
+
+	// Setup flags
+	int flags = HIDDEV_FLAG_UREF | HIDDEV_FLAG_REPORT;
+	if (ioctl(devfd, HIDIOCSFLAG, &flags) < 0) {
+		perror("HIDIOCSFLAG");
+		return EXIT_FAILURE;
+	}
+
+	write_usage(HID_REPORT_TYPE_FEATURE, 0x0d0052, enable_ptp ? 3 : 0);
+
+	int rc;
+	do {
+		struct hiddev_usage_ref ev;
+		rc = read(devfd, &ev, sizeof(ev));
+		if (rc < 0) {
+			perror("Could not read events from device");
+			return EXIT_FAILURE;
+		} else if (rc == 0) {
+		}
+
+		process_event(&ev);
+	} while (rc > 0);
+
+	return EXIT_SUCCESS;
+}