firewire: adopt read cycle timer ABI from raw1394

This duplicates the read cycle timer feature of raw1394 (added in Linux
2.6.21) in firewire-core's userspace ABI.  The argument to the ioctl is
reordered though to ensure 32/64 bit compatibility.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Kristian Høgsberg <krh@redhat.com>

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

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 */