2 files changed, 41 insertions, 0 deletions

diff --git a/drivers/firewire/fw-cdev.c b/drivers/firewire/fw-cdev.c
index b960fd996918..290d9f036199 100644
--- a/drivers/firewire/fw-cdev.c
+++ b/drivers/firewire/fw-cdev.c
@@ -25,11 +25,14 @@
 #include <linux/device.h>
 #include <linux/vmalloc.h>
 #include <linux/poll.h>
+#include <linux/preempt.h>
+#include <linux/time.h>
 #include <linux/delay.h>
 #include <linux/mm.h>
 #include <linux/idr.h>
 #include <linux/compat.h>
 #include <linux/firewire-cdev.h>
+#include <asm/system.h>
 #include <asm/uaccess.h>
 #include "fw-transaction.h"
 #include "fw-topology.h"
@@ -811,6 +814,28 @@ static int ioctl_stop_iso(struct client *client, void *buffer)
         return fw_iso_context_stop(client->iso_context);
 }
 
+static int ioctl_get_cycle_timer(struct client *client, void *buffer)
+{
+        struct fw_cdev_get_cycle_timer *request = buffer;
+        struct fw_card *card = client->device->card;
+        unsigned long long bus_time;
+        struct timeval tv;
+        unsigned long flags;
+
+        preempt_disable();
+        local_irq_save(flags);
+
+        bus_time = card->driver->get_bus_time(card);
+        do_gettimeofday(&tv);
+
+        local_irq_restore(flags);
+        preempt_enable();
+
+        request->local_time = tv.tv_sec * 1000000ULL + tv.tv_usec;
+        request->cycle_timer = bus_time & 0xffffffff;
+        return 0;
+}
+
 static int (* const ioctl_handlers[])(struct client *client, void *buffer) = {
         ioctl_get_info,
         ioctl_send_request,
@@ -824,6 +849,7 @@ static int (* const ioctl_handlers[])(struct client *client, void *buffer) = {
         ioctl_queue_iso,
         ioctl_start_iso,
         ioctl_stop_iso,
+        ioctl_get_cycle_timer,
 };
 
 static int
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index 1a45d6f41b09..0f0e271f97fa 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -178,6 +178,7 @@ union fw_cdev_event {
 #define FW_CDEV_IOC_QUEUE_ISO           _IOWR('#', 0x09, struct fw_cdev_queue_iso)
 #define FW_CDEV_IOC_START_ISO           _IOW('#', 0x0a, struct fw_cdev_start_iso)
 #define FW_CDEV_IOC_STOP_ISO            _IOW('#', 0x0b, struct fw_cdev_stop_iso)
+#define FW_CDEV_IOC_GET_CYCLE_TIMER     _IOR('#', 0x0c, struct fw_cdev_get_cycle_timer)
 
 /* FW_CDEV_VERSION History
  *
@@ -459,4 +460,18 @@ struct fw_cdev_stop_iso {
         __u32 handle;
 };
 
+/**
+ * struct fw_cdev_get_cycle_timer - read cycle timer register
+ * @local_time:   system time, in microseconds since the Epoch
+ * @cycle_timer:  isochronous cycle timer, as per OHCI 1.1 clause 5.13
+ *
+ * The %FW_CDEV_IOC_GET_CYCLE_TIMER ioctl reads the isochronous cycle timer
+ * and also the system clock.  This allows to express the receive time of an
+ * isochronous packet as a system time with microsecond accuracy.
+ */
+struct fw_cdev_get_cycle_timer {
+        __u64 local_time;
+        __u32 cycle_timer;
+};
+
 #endif /* _LINUX_FIREWIRE_CDEV_H */