ieee1394: cycle timer read extension for raw1394

This implements the simultaneous read of the isochronous cycle timer and
the system clock (in usecs).  This allows to express the exact receive
time of an ISO packet as a system time with microsecond accuracy.
http://bugzilla.kernel.org/show_bug.cgi?id=7773

The counterpart patch for libraw1394 can be found at
http://thread.gmane.org/gmane.linux.kernel.firewire.devel/8934

Patch update (Stefan R.):  Disable preemption and local interrupts.
Prevent integer overflow.  Add paranoid error checks and kerneldoc to
hpsb_read_cycle_timer.  Move it to other ieee1394_core high-level API
functions.  Change comments.  Adjust whitespace.  Rename struct
_raw1394_cycle_timer.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Pieter Palmers <pieterp@joow.be>
Acked-by: Dan Dennedy <dan@dennedy.org>

diff --git a/drivers/ieee1394/ieee1394-ioctl.h b/drivers/ieee1394/ieee1394-ioctl.h
index 8f207508ed1dae62dc4ba417df8a5cb14089d62a..46878fef136c24d091fa05146c54cd8e7b873c10 100644 (file)
--- a/drivers/ieee1394/ieee1394-ioctl.h
+++ b/drivers/ieee1394/ieee1394-ioctl.h
@@ -100,5 +100,7 @@
        _IO  ('#', 0x28)
 #define RAW1394_IOC_ISO_RECV_FLUSH             \
        _IO  ('#', 0x29)
+#define RAW1394_IOC_GET_CYCLE_TIMER            \
+       _IOR ('#', 0x30, struct raw1394_cycle_timer)
 
 #endif /* __IEEE1394_IOCTL_H */

diff --git a/drivers/ieee1394/ieee1394_core.c b/drivers/ieee1394/ieee1394_core.c
index 1521e57e124bb63119b705804f8ff81d41ed77ed..d791d08c743ce22d100ad34e440f3cdb932ca30f 100644 (file)
--- a/drivers/ieee1394/ieee1394_core.c
+++ b/drivers/ieee1394/ieee1394_core.c
@@ -33,7 +33,10 @@
 #include <linux/skbuff.h>
 #include <linux/suspend.h>
 #include <linux/kthread.h>
+#include <linux/preempt.h>
+#include <linux/time.h>
 
+#include <asm/system.h>
 #include <asm/byteorder.h>
 
 #include "ieee1394_types.h"
@@ -186,6 +189,45 @@ int hpsb_reset_bus(struct hpsb_host *host, int type)
        }
 }
 
+/**
+ * hpsb_read_cycle_timer - read cycle timer register and system time
+ * @host: host whose isochronous cycle timer register is read
+ * @cycle_timer: address of bitfield to return the register contents
+ * @local_time: address to return the system time
+ *
+ * The format of * @cycle_timer, is described in OHCI 1.1 clause 5.13. This
+ * format is also read from non-OHCI controllers. * @local_time contains the
+ * system time in microseconds since the Epoch, read at the moment when the
+ * cycle timer was read.
+ *
+ * Return value: 0 for success or error number otherwise.
+ */
+int hpsb_read_cycle_timer(struct hpsb_host *host, u32 *cycle_timer,
+                         u64 *local_time)
+{
+       int ctr;
+       struct timeval tv;
+       unsigned long flags;
+
+       if (!host || !cycle_timer || !local_time)
+               return -EINVAL;
+
+       preempt_disable();
+       local_irq_save(flags);
+
+       ctr = host->driver->devctl(host, GET_CYCLE_COUNTER, 0);
+       if (ctr)
+               do_gettimeofday(&tv);
+
+       local_irq_restore(flags);
+       preempt_enable();
+
+       if (!ctr)
+               return -EIO;
+       *cycle_timer = ctr;
+       *local_time = tv.tv_sec * 1000000ULL + tv.tv_usec;
+       return 0;
+}
 
 int hpsb_bus_reset(struct hpsb_host *host)
 {
@@ -1190,6 +1232,7 @@ EXPORT_SYMBOL(hpsb_alloc_packet);
 EXPORT_SYMBOL(hpsb_free_packet);
 EXPORT_SYMBOL(hpsb_send_packet);
 EXPORT_SYMBOL(hpsb_reset_bus);
+EXPORT_SYMBOL(hpsb_read_cycle_timer);
 EXPORT_SYMBOL(hpsb_bus_reset);
 EXPORT_SYMBOL(hpsb_selfid_received);
 EXPORT_SYMBOL(hpsb_selfid_complete);

diff --git a/drivers/ieee1394/ieee1394_core.h b/drivers/ieee1394/ieee1394_core.h
index 536ba3f580fd49995fc812353167d8cc65307570..bd29d8ef5bbd9c58c7a698901c86558421367e2f 100644 (file)
--- a/drivers/ieee1394/ieee1394_core.h
+++ b/drivers/ieee1394/ieee1394_core.h
@@ -127,6 +127,9 @@ int hpsb_send_packet_and_wait(struct hpsb_packet *packet);
  * progress, 0 otherwise. */
 int hpsb_reset_bus(struct hpsb_host *host, int type);
 
+int hpsb_read_cycle_timer(struct hpsb_host *host, u32 *cycle_timer,
+                         u64 *local_time);
+
 /*
  * The following functions are exported for host driver module usage.  All of
  * them are safe to use in interrupt contexts, although some are quite

diff --git a/drivers/ieee1394/raw1394.c b/drivers/ieee1394/raw1394.c
index a77a832828c84220d6d504c9be4d55101e5754ea..5d08d7450f96c25f6953aaeb99e822b575fbca0c 100644 (file)
--- a/drivers/ieee1394/raw1394.c
+++ b/drivers/ieee1394/raw1394.c
@@ -2669,6 +2669,18 @@ static void raw1394_iso_shutdown(struct file_info *fi)
        fi->iso_state = RAW1394_ISO_INACTIVE;
 }
 
+static int raw1394_read_cycle_timer(struct file_info *fi, void __user * uaddr)
+{
+       struct raw1394_cycle_timer ct;
+       int err;
+
+       err = hpsb_read_cycle_timer(fi->host, &ct.cycle_timer, &ct.local_time);
+       if (!err)
+               if (copy_to_user(uaddr, &ct, sizeof(ct)))
+                       err = -EFAULT;
+       return err;
+}
+
 /* mmap the rawiso xmit/recv buffer */
 static int raw1394_mmap(struct file *file, struct vm_area_struct *vma)
 {
@@ -2777,6 +2789,14 @@ static int raw1394_ioctl(struct inode *inode, struct file *file,
                break;
        }
 
+       /* state-independent commands */
+       switch(cmd) {
+       case RAW1394_IOC_GET_CYCLE_TIMER:
+               return raw1394_read_cycle_timer(fi, argp);
+       default:
+               break;
+       }
+
        return -EINVAL;
 }
 

diff --git a/drivers/ieee1394/raw1394.h b/drivers/ieee1394/raw1394.h
index 35bfc38f013c25f681dda5f3a70c2fbfed6c1819..7bd22ee1afbb1d56a2a71e9c86cd86b3ad5bfc43 100644 (file)
--- a/drivers/ieee1394/raw1394.h
+++ b/drivers/ieee1394/raw1394.h
@@ -178,4 +178,14 @@ struct raw1394_iso_status {
        __s16 xmit_cycle;
 };
 
+/* argument to RAW1394_IOC_GET_CYCLE_TIMER ioctl */
+struct raw1394_cycle_timer {
+       /* contents of Isochronous Cycle Timer register,
+          as in OHCI 1.1 clause 5.13 (also with non-OHCI hosts) */
+       __u32 cycle_timer;
+
+       /* local time in microseconds since Epoch,
+          simultaneously read with cycle timer */
+       __u64 local_time;
+};
 #endif /* IEEE1394_RAW1394_H */