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Commit abfe5a01 authored by Stefan Richter's avatar Stefan Richter
Browse files

firewire: cdev: add more flexible cycle timer ioctl 

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: default avatarStefan Richter <stefanr@s5r6.in-berlin.de>
parent fd6e0c51

drivers/firewire/core-cdev.c

+32 −6
Original line number Diff line number Diff line
@@ -1031,23 +1031,47 @@ 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->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;

include/linux/firewire-cdev.h

+27 −4
Original line number Diff line number Diff line
@@ -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