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firewire: cdev: add more flexible cycle timer ioctl

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The system time from CLOCK_REALTIME is not monotonic, hence problematic
for the main user of the FW_CDEV_IOC_GET_CYCLE_TIMER ioctl.  This issue
exists in its successor ABI, i.e. raw1394, too.
http://subversion.ffado.org/ticket/242

We now offer an alternative ioctl which lets the caller choose between
CLOCK_REALTIME, CLOCK_MONOTONIC, and CLOCK_MONOTONIC_RAW as source of
the local time, very similar to the clock_gettime libc function.  The
format of the local time return value matches that of clock_gettime
(seconds and nanoseconds, instead of a single microseconds value from
the existing ioctl).

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter 2010-02-20 12:13:49 +01:00
parent fd6e0c5181
commit abfe5a01ef
2 changed files with 59 additions and 10 deletions
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38
drivers/firewire/core-cdev.c
View File

@ -1031,22 +1031,46 @@ 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)
static int ioctl_get_cycle_timer2(struct client *client, void *buffer)
{
struct fw_cdev_get_cycle_timer *request = buffer;
struct fw_cdev_get_cycle_timer2 *request = buffer;
struct fw_card *card = client->device->card;
struct timeval tv;
struct timespec ts = {0, 0};
u32 cycle_time;
int ret = 0;
local_irq_disable();
cycle_time = card->driver->get_cycle_time(card);
do_gettimeofday(&tv);
switch (request->clk_id) {
case CLOCK_REALTIME: getnstimeofday(&ts); break;
case CLOCK_MONOTONIC: do_posix_clock_monotonic_gettime(&ts); break;
case CLOCK_MONOTONIC_RAW: getrawmonotonic(&ts); break;
default:
ret = -EINVAL;
}
local_irq_enable();
request->local_time = tv.tv_sec * 1000000ULL + tv.tv_usec;
request->cycle_timer = cycle_time;
request->tv_sec = ts.tv_sec;
request->tv_nsec = ts.tv_nsec;
request->cycle_timer = cycle_time;
return ret;
}
static int ioctl_get_cycle_timer(struct client *client, void *buffer)
{
struct fw_cdev_get_cycle_timer *request = buffer;
struct fw_cdev_get_cycle_timer2 ct2;
ct2.clk_id = CLOCK_REALTIME;
ioctl_get_cycle_timer2(client, &ct2);
request->local_time = ct2.tv_sec * USEC_PER_SEC +
ct2.tv_nsec / NSEC_PER_USEC;
request->cycle_timer = ct2.cycle_timer;
return 0;
}
@ -1320,6 +1344,7 @@ static int (* const ioctl_handlers[])(struct client *client, void *buffer) = {
ioctl_get_speed,
ioctl_send_broadcast_request,
ioctl_send_stream_packet,
ioctl_get_cycle_timer2,
};
static int dispatch_ioctl(struct client *client,
@ -1341,6 +1366,7 @@ static int dispatch_ioctl(struct client *client,
struct fw_cdev_get_cycle_timer _0c;
struct fw_cdev_allocate_iso_resource _0d;
struct fw_cdev_send_stream_packet _13;
struct fw_cdev_get_cycle_timer2 _14;
})];
int ret;

31
include/linux/firewire-cdev.h
View File

@ -248,6 +248,9 @@ union fw_cdev_event {
#define FW_CDEV_IOC_SEND_BROADCAST_REQUEST _IOW('#', 0x12, struct fw_cdev_send_request)
#define FW_CDEV_IOC_SEND_STREAM_PACKET _IOW('#', 0x13, struct fw_cdev_send_stream_packet)
/* available since kernel version 2.6.34 */
#define FW_CDEV_IOC_GET_CYCLE_TIMER2 _IOWR('#', 0x14, struct fw_cdev_get_cycle_timer2)
/*
* FW_CDEV_VERSION History
* 1 (2.6.22) - initial version
@ -544,20 +547,40 @@ struct fw_cdev_stop_iso {
/**
* 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
* @cycle_timer: Cycle Time register contents
*
* 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.
* and also the system clock (%CLOCK_REALTIME). This allows to express the
* receive time of an isochronous packet as a system time.
*
* @cycle_timer consists of 7 bits cycleSeconds, 13 bits cycleCount, and
* 12 bits cycleOffset, in host byte order.
* 12 bits cycleOffset, in host byte order. Cf. the Cycle Time register
* per IEEE 1394 or Isochronous Cycle Timer register per OHCI-1394.
*/
struct fw_cdev_get_cycle_timer {
__u64 local_time;
__u32 cycle_timer;
};
/**
* struct fw_cdev_get_cycle_timer2 - read cycle timer register
* @tv_sec: system time, seconds
* @tv_nsec: system time, sub-seconds part in nanoseconds
* @clk_id: input parameter, clock from which to get the system time
* @cycle_timer: Cycle Time register contents
*
* The %FW_CDEV_IOC_GET_CYCLE_TIMER2 works like
* %FW_CDEV_IOC_GET_CYCLE_TIMER but lets you choose a clock like with POSIX'
* clock_gettime function. Supported @clk_id values are POSIX' %CLOCK_REALTIME
* and %CLOCK_MONOTONIC and Linux' %CLOCK_MONOTONIC_RAW.
*/
struct fw_cdev_get_cycle_timer2 {
__s64 tv_sec;
__s32 tv_nsec;
__s32 clk_id;
__u32 cycle_timer;
};
/**
* struct fw_cdev_allocate_iso_resource - (De)allocate a channel or bandwidth
* @closure: Passed back to userspace in correponding iso resource events