tree 3ef1f82d206f5eda62c6c646f8785259997a12a2
parent f63c9862ffd13e41126dd2a70e4c4c287da549a5
author Filip Bozuta <Filip.Bozuta@rt-rk.com> 1579117001 +0100
committer Laurent Vivier <laurent@vivier.eu> 1582107460 +0100

linux-user: Add support for getting alsa timer version and id

This patch implements functionalities of following ioctls:

SNDRV_TIMER_IOCTL_PVERSION - Getting the sound timer version

    Read the sound timer version. The third ioctl's argument is
    a pointer to an int in which the specified timers version
    is returned.

SNDRV_TIMER_IOCTL_NEXT_DEVICE - Getting id information about next timer

    Read id information about the next timer device from the sound timer
    device list. The id infomration is returned in the following structure:

        struct snd_timer_id {
            int dev_class;    /* timer device class number */
            int dev_sclass;   /* slave device class number (unused) */
            int card;         /* card number */
            int device;       /* device number */
            int subdevice;    /* sub-device number */
        };

    The devices in the sound timer device list are arranged by the fields
    of this structure respectively (first by dev_class number, then by
    card number, ...). A pointer to this structure should be passed as
    the third ioctl's argument. Before calling the ioctl, the parameters
    of this structure should be initialized in relation to the next timer
    device which information is to be obtained. For example, if a wanted
    timer device has the device class number equal to or bigger then 2,
    the field dev_class should be initialized to 2. After the ioctl call,
    the structure fields are filled with values from the next device in
    the sound timer device list. If there is no next device in the list,
    the structure is filled with "zero" id values (in that case all
    fields are filled with value -1).

Implementation notes:

    The ioctl 'SNDRV_TIMER_IOCTL_NEXT_DEVICE' has a pointer to a
    'struct snd_timer_id' as its third argument. That is the reason why
    corresponding definition is added in 'linux-user/syscall_types.h'.
    Since all elements of this structure are of type 'int', the rest of
    the implementation was straightforward.

    The line '#include <linux/rtc.h>' was added to recognize
    preprocessor definitions for these ioctls. This needs to be
    done only once in this series of commits. Also, the content
    of this file (with respect to ioctl definitions) remained
    unchanged for a long time, therefore there is no need to
    worry about supporting older Linux kernel version.

Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Filip Bozuta <Filip.Bozuta@rt-rk.com>
Message-Id: <1579117007-7565-8-git-send-email-Filip.Bozuta@rt-rk.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>