• Anton Vorontsov's avatar
    rtc: set wakeup capability for I2C and SPI RTC drivers · 26b3c01f
    Anton Vorontsov authored
    RTC core won't allow wakeup alarms to be set if RTC devices' parent (i.e.
    i2c_client or spi_device) isn't wakeup capable.
    
    For I2C devices there is I2C_CLIENT_WAKE flag exists that we can pass via
    board info, and if set, I2C core will initialize wakeup capability.  For
    SPI devices there is no such flag at all.
    
    I believe that it's not platform code responsibility to allow or disallow
    wakeups, instead, drivers themselves should set the capability if a device
    can trigger wakeups.
    
    That's what drivers/base/power/sysfs.c says:
    
     * It is the responsibility of device drivers to enable (or disable)
     * wakeup signaling as part of changing device power states, respecting
     * the policy choices provided through the driver model.
    
    I2C and SPI RTC devices send wakeup events via interrupt lines, so we
    should set the wakeup capability if IRQ is routed.
    
    Ideally we should also check irq for wakeup capability before setting
    device's capability, i.e.
    
    	if (can_irq_wake(irq))
    		device_set_wakeup_capable(&client->dev, 1);
    
    But there is no can_irq_wake() call exist, and it is not that trivial to
    implement it for all interrupts controllers and complex/cascaded setups.
    
    drivers/base/power/sysfs.c also covers these cases:
    
     * Devices may not be able to generate wakeup events from all power
     * states.  Also, the events may be ignored in some configurations;
     * for example, they might need help from other devices that aren't
     * active
    
    So there is no guarantee that wakeup will actually work, and so I think
    there is no point in being pedantic wrt checking IRQ wakeup capability.
    Signed-off-by: default avatarAnton Vorontsov <avorontsov@ru.mvista.com>
    Cc: David Brownell <dbrownell@users.sourceforge.net>
    Cc: Ben Dooks <ben-linux@fluff.org>
    Cc: Jean Delvare <khali@linux-fr.org>
    Cc: Alessandro Zummo <a.zummo@towertech.it>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    26b3c01f
rtc-ds1307.c 24 KB