From: Arnd Bergmann <arnd-r2nGTMty4D4@public•gmane.org>
To: Richard Cochran <richardcochran-Re5JQEeQqe8AvxtiuMwx3w@public•gmane.org>
Cc: Rodolfo Giometti <giometti-k2GhghHVRtY@public•gmane.org>,
netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public•gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public•gmane.org,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public•gmane.org,
Krzysztof Halasa <khc-9GfyWEdoJtJmR6Xm/wNWPw@public•gmane.org>
Subject: Re: [PATCH 1/5] ptp: Added a brand new class driver for ptp clocks.
Date: Mon, 16 Aug 2010 16:26:23 +0200 [thread overview]
Message-ID: <201008161626.24083.arnd@arndb.de> (raw)
In-Reply-To: <363bd749a38d0b785d8431e591bf54c38db4c2d7.1281956490.git.richard.cochran-3mrvs1K0uXizZXS1Dc/lvw@public.gmane.org>
On Monday 16 August 2010, Richard Cochran wrote:
> This patch adds an infrastructure for hardware clocks that implement
> IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a
> registration method to particular hardware clock drivers. Each clock is
> exposed to user space as a character device with ioctls that allow tuning
> of the PTP clock.
Have you considered integrating the subsystem into the Posix clock/timer
framework?
I can't really tell from reading the source if this is possible or
not, but my feeling is that if it can be done, that would be a much
nicer interface. We already have clock_gettime/clock_settime/
timer_settime/... system calls, and while you'd need to add another
clockid and some syscalls, my feeling is that it will be more
usable in the end.
> +static const struct file_operations ptp_fops = {
> + .owner = THIS_MODULE,
> + .ioctl = ptp_ioctl,
> + .open = ptp_open,
> + .poll = ptp_poll,
> + .read = ptp_read,
> + .release = ptp_release,
> +};
.ioctl is gone, you have to use .unlocked_ioctl and make sure that
your ptp_ioctl function can handle being called concurrently.
You should also add a .compat_ioctl function, ideally one that
points to ptp_ioctl so you don't have to list every command as
being compatible. Right now, some commands are incompatible,
which means you need more changes to the interface.
> +struct ptp_clock_timer {
> + int alarm_index; /* Which alarm to query or configure. */
> + int signum; /* Requested signal. */
> + int flags; /* Zero or TIMER_ABSTIME, see TIMER_SETTIME(2) */
> + struct itimerspec tsp; /* See TIMER_SETTIME(2) */
> +};
This data structure is incompatible between 32 and 64 bit user space,
so you would need a compat_ioctl() function to convert between the
two formats. Better define the structure in a compatible way, avoiding
variable-length fields and implicit padding.
> +struct ptp_clock_request {
> + int type; /* One of the ptp_request_types enumeration values. */
> + int index; /* Which channel to configure. */
> + struct timespec ts; /* For period signals, the desired period. */
> + int flags; /* Bit field for PTP_ENABLE_FEATURE or other flags. */
> +};
Same problem here, timespec is either 64 or 128 bits long and has different
alignment.
> +struct ptp_extts_event {
> + int index;
> + struct timespec ts;
> +};
here too.
> +#define PTP_CLOCK_VERSION 0x00000001
> +
> +#define PTP_CLK_MAGIC '='
> +
> +#define PTP_CLOCK_APIVERS _IOR (PTP_CLK_MAGIC, 1, __u32)
Try avoiding versioned ABIs. It's better to just add new ioctls
or syscalls when you need some extra functionality and leave the
old ones around.
> +#define PTP_CLOCK_ADJTIME _IOW (PTP_CLK_MAGIC, 3, struct timespec)
> +#define PTP_CLOCK_GETTIME _IOR (PTP_CLK_MAGIC, 4, struct timespec)
> +#define PTP_CLOCK_SETTIME _IOW (PTP_CLK_MAGIC, 5, struct timespec)
These are also incompatible.
Arnd
next prev parent reply other threads:[~2010-08-16 14:26 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-16 11:17 [PATCH v5 0/5] ptp: IEEE 1588 clock support Richard Cochran
2010-08-16 11:17 ` [PATCH 1/5] ptp: Added a brand new class driver for ptp clocks Richard Cochran
[not found] ` <363bd749a38d0b785d8431e591bf54c38db4c2d7.1281956490.git.richard.cochran-3mrvs1K0uXizZXS1Dc/lvw@public.gmane.org>
2010-08-16 14:26 ` Arnd Bergmann [this message]
2010-08-16 19:00 ` Richard Cochran
2010-08-16 19:59 ` Arnd Bergmann
2010-08-17 8:32 ` Richard Cochran
2010-08-17 9:25 ` Arnd Bergmann
[not found] ` <201008170925.55592.arnd-r2nGTMty4D4@public.gmane.org>
2010-08-17 10:52 ` Richard Cochran
[not found] ` <20100817105232.GA9079-7KxsofuKt4IfAd9E5cN8NEzG7cXyKsk/@public.gmane.org>
2010-08-17 11:36 ` Arnd Bergmann
2010-08-18 0:40 ` john stultz
[not found] ` <201008171336.29375.arnd-r2nGTMty4D4@public.gmane.org>
2010-08-18 14:04 ` Richard Cochran
2010-08-18 15:02 ` Arnd Bergmann
[not found] ` <201008181702.03384.arnd-r2nGTMty4D4@public.gmane.org>
2010-08-19 9:22 ` Richard Cochran
2010-08-19 12:29 ` Arnd Bergmann
2010-08-19 15:23 ` Ira W. Snyder
2010-08-19 15:48 ` Arnd Bergmann
2010-08-16 19:24 ` john stultz
2010-08-16 19:38 ` john stultz
[not found] ` <AANLkTik_2MKMhOuDGOmu8Kzyq-ipLe+Bxrb3FaD+Tv4U-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-08-17 8:53 ` Richard Cochran
2010-08-18 0:22 ` john stultz
2010-08-18 7:19 ` Richard Cochran
2010-08-19 0:12 ` john stultz
[not found] ` <1282176776.2865.100.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2010-08-19 5:55 ` Richard Cochran
2010-08-19 12:28 ` Arnd Bergmann
2010-08-19 15:38 ` Richard Cochran
2010-08-23 20:21 ` john stultz
[not found] ` <1282594899.3111.358.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2010-08-27 11:08 ` Richard Cochran
[not found] ` <20100827110855.GA11657-7KxsofuKt4IfAd9E5cN8NEzG7cXyKsk/@public.gmane.org>
2010-08-27 12:03 ` Arnd Bergmann
2010-08-27 20:56 ` John Stultz
2010-08-27 12:45 ` Alan Cox
2010-08-27 20:14 ` John Stultz
2010-08-23 20:08 ` john stultz
2010-08-24 18:30 ` Stephan Gatzka
2010-08-25 9:40 ` Christian Riesch
2010-08-27 1:57 ` john stultz
[not found] ` <1282874269.4371.74.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2010-08-27 7:57 ` Richard Cochran
2010-08-27 12:41 ` Alan Cox
[not found] ` <20100827134154.50eef56c-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2010-08-27 14:02 ` Richard Cochran
[not found] ` <20100827140205.GA3293-7KxsofuKt4IfAd9E5cN8NEzG7cXyKsk/@public.gmane.org>
2010-08-27 14:50 ` Alan Cox
2010-08-27 15:35 ` M. Warner Losh
2010-08-29 13:32 ` Christian Riesch
[not found] ` <1282594125.3111.344.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2010-08-27 12:38 ` Richard Cochran
[not found] ` <20100827123849.GC11657-7KxsofuKt4IfAd9E5cN8NEzG7cXyKsk/@public.gmane.org>
2010-08-27 13:38 ` Alan Cox
[not found] ` <20100827143844.646eccf6-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2010-08-27 14:34 ` Richard Cochran
[not found] ` <20100827143437.GB3293-7KxsofuKt4IfAd9E5cN8NEzG7cXyKsk/@public.gmane.org>
2010-08-27 15:06 ` Alan Cox
2010-08-27 15:21 ` Patrick Loschmidt
2010-08-27 16:17 ` Jacob Keller
2010-08-27 22:30 ` John Stultz
2010-09-06 6:33 ` Richard Cochran
[not found] ` <20100906063327.GA4549-7KxsofuKt4IfAd9E5cN8NEzG7cXyKsk/@public.gmane.org>
2010-09-21 16:54 ` Stephan Gatzka
2010-09-21 20:47 ` Kyle Moffett
[not found] ` <AANLkTinRM3_kBc5S3wV=_S6P8+x7A43kz0qSYbixJYnq-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2010-09-22 10:14 ` Richard Cochran
2010-08-16 11:18 ` [PATCH 2/5] ptp: Added a clock that uses the Linux system time Richard Cochran
2010-08-16 11:18 ` [PATCH 3/5] ptp: Added a clock that uses the eTSEC found on the MPC85xx Richard Cochran
2010-08-16 11:18 ` [PATCH 4/5] ptp: Added a clock driver for the IXP46x Richard Cochran
2010-08-16 11:19 ` [PATCH 5/5] ptp: Added a clock driver for the National Semiconductor PHYTER Richard Cochran
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