Unbind and rebind the driver to the device after firmware update so that the driver reinitializes

based on the updated values and ensure the device is powered on.

3 files changed, 135 insertions, 3 deletions

diff --git a/rmi4update/main.cpp b/rmi4update/main.cpp
index b2b5fcb..a807f43 100644
--- a/rmi4update/main.cpp
+++ b/rmi4update/main.cpp
@@ -20,7 +20,11 @@
 #include <errno.h>
 #include <getopt.h>
 #include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #include <dirent.h>
+#include <unistd.h>
+#include <time.h>
 
 #include "hiddevice.h"
 #include "rmi4update.h"
@@ -52,6 +56,116 @@ int UpdateDevice(FirmwareImage & image, bool force, const char * deviceFile)
 	return rc;
 }
 
+int WriteDeviceNameToFile(const char * file, const char * str)
+{
+	int fd;
+	ssize_t size;
+
+	fd = open(file, O_WRONLY);
+	if (fd < 0)
+		return UPDATE_FAIL;
+
+	for (;;) {
+		size = write(fd, str, 19);
+		if (size < 0) {
+			if (errno == EINTR)
+				continue;
+
+			return UPDATE_FAIL;
+		}
+		break;
+	}
+
+	close(fd);
+
+	return UPDATE_SUCCESS;
+}
+
+/*
+ * We need to rebind the driver to the device after firmware update for two reasons
+ * 	a) The parameters of the device may have changed in the new firmware so the
+ *	   driver should redo the initialization to read the new values.
+ *	b) Kernel commit 0f5a24c6 will now power down the device once we close the
+ *	   file descriptor for the hidraw device file. Reloading the driver powers the
+ *	   device back on.
+ */
+void RebindDriver(const char * hidraw)
+{
+	int rc;
+	ssize_t size;
+	char bindFile[PATH_MAX];
+	char unbindFile[PATH_MAX];
+	char deviceLink[PATH_MAX];
+	char driverName[PATH_MAX];
+	char driverLink[PATH_MAX];
+	char linkBuf[PATH_MAX];
+	char hidDeviceString[20];
+	int i;
+
+	snprintf(unbindFile, PATH_MAX, "/sys/class/hidraw/%s/device/driver/unbind", hidraw);
+	snprintf(deviceLink, PATH_MAX, "/sys/class/hidraw/%s/device", hidraw);
+
+	size = readlink(deviceLink, linkBuf, PATH_MAX);
+	if (size < 0) {
+		fprintf(stderr, "Failed to find the HID string for this device: %s\n",
+			hidraw);
+		return;
+	}
+	linkBuf[size] = 0;
+
+	strncpy(hidDeviceString, StripPath(linkBuf, size), 20);
+
+	snprintf(driverLink, PATH_MAX, "/sys/class/hidraw/%s/device/driver", hidraw);
+
+	size = readlink(driverLink, linkBuf, PATH_MAX);
+	if (size < 0) {
+		fprintf(stderr, "Failed to find the HID string for this device: %s\n",
+			hidraw);
+		return;
+	}
+	linkBuf[size] = 0;
+
+	strncpy(driverName, StripPath(linkBuf, size), PATH_MAX);
+
+	snprintf(bindFile, PATH_MAX, "/sys/bus/hid/drivers/%s/bind", driverName);
+
+	rc = WriteDeviceNameToFile(unbindFile, hidDeviceString);
+	if (rc != UPDATE_SUCCESS) {
+		fprintf(stderr, "Failed to unbind HID device %s: %s\n",
+			hidDeviceString, strerror(errno));
+		return;
+	}
+
+	for (i = 0;; ++i) {
+		struct timespec req;
+		struct timespec rem;
+
+		rc = WriteDeviceNameToFile(bindFile, hidDeviceString);
+		if (rc == UPDATE_SUCCESS)
+			return;
+
+		if (i <= 4)
+			break;
+
+		/* device might not be ready yet to bind to */
+		req.tv_sec = 0;
+		req.tv_nsec = 100 * 1000 * 1000; /* 100 ms */
+		for (;;) {
+			rc = nanosleep(&req, &rem);
+			if (rc < 0) {
+				if (errno == EINTR) {
+					req = rem;
+					continue;
+				}
+			}
+			break;
+		}
+	}
+
+	fprintf(stderr, "Failed to bind HID device %s: %s\n",
+		hidDeviceString, strerror(errno));
+}
+
 int main(int argc, char **argv)
 {
 	int rc;
@@ -103,7 +217,8 @@ int main(int argc, char **argv)
 	if (deviceName) {
 		return UpdateDevice(image, force, deviceName);
 	} else {
-		char buf[PATH_MAX];
+		char rawDevice[PATH_MAX];
+		char deviceFile[PATH_MAX];
 		bool found = false;
 
 		devDir = opendir("/dev");
@@ -112,12 +227,14 @@ int main(int argc, char **argv)
 
 		while ((devDirEntry = readdir(devDir)) != NULL) {
 			if (strstr(devDirEntry->d_name, "hidraw")) {
-				snprintf(buf, PATH_MAX, "/dev/%s", devDirEntry->d_name);
-				rc = UpdateDevice(image, force, buf);
+				strncpy(rawDevice, devDirEntry->d_name, PATH_MAX);
+				snprintf(deviceFile, PATH_MAX, "/dev/%s", devDirEntry->d_name);
+				rc = UpdateDevice(image, force, deviceFile);
 				if (rc != 0) {
 					continue;
 				} else {
 					found = true;
+					RebindDriver(rawDevice);
 					break;
 				}
 			}
diff --git a/rmi4update/updateutil.cpp b/rmi4update/updateutil.cpp
index 7950e4c..5b27e71 100644
--- a/rmi4update/updateutil.cpp
+++ b/rmi4update/updateutil.cpp
@@ -15,6 +15,8 @@
  * limitations under the License.
  */
 
+#include <sys/types.h>
+
 #include "updateutil.h"
 
 const char *update_error_str[] = {
@@ -68,4 +70,16 @@ unsigned short extract_short(const unsigned char *data)
 {
 	return (unsigned long)data [0]
 		+ (unsigned long)data [1] * 0x100;
+}
+
+const char * StripPath(char * path, ssize_t size)
+{
+	int i;
+	char * str;
+
+	for (i = size - 1, str = &path[size - 1]; i > 0; --i, --str)
+		if (path[i - 1] == '/')
+			break;
+
+	return str;
 }
\ No newline at end of file
diff --git a/rmi4update/updateutil.h b/rmi4update/updateutil.h
index 92c934d..70fc8a0 100644
--- a/rmi4update/updateutil.h
+++ b/rmi4update/updateutil.h
@@ -56,5 +56,6 @@ const char * update_err_to_string(int err);
 
 unsigned long extract_long(const unsigned char *data);
 unsigned short extract_short(const unsigned char *data);
+const char * StripPath(char * path, ssize_t size);
 
 #endif // _UPDATEUTIL_H_
\ No newline at end of file