On Sat, Jan 10, 2015 at 12:34 AM, Andrew Lunn <[email protected]> wrote:
> Armada 370/XP devices can 'blink' gpio lines with a configurable on > and off period. This can be modelled as a PWM. > > However, there are only two sets of PWM configuration registers for > all the gpio lines. This driver simply allows a single gpio line per > gpio chip of 32 lines to be used as a PWM. Attempts to use more return > EBUSY. > > Due to the interleaving of registers it is not simple to separate the > PWM driver from the gpio driver. Thus the gpio driver has been > extended with a PWM driver. > > Signed-off-by: Andrew Lunn <[email protected]> > --- > drivers/gpio/Kconfig | 5 ++ > drivers/gpio/Makefile | 1 + > drivers/gpio/gpio-mvebu-pwm.c | 202 > ++++++++++++++++++++++++++++++++++++++++++ (...) > +++ b/drivers/gpio/gpio-mvebu-pwm.c (...) > +static const struct pwm_ops mvebu_pwm_ops = { > + .request = mvebu_pwm_request, > + .free = mvebu_pwm_free, > + .config = mvebu_pwm_config, > + .enable = mvebu_pwm_enable, > + .disable = mvebu_pwm_disable, > + .owner = THIS_MODULE, > +}; So the first basic notes: - PWM maintainer Thierry Reding has to review and ACK this, and the patch needs to be posted to the linux-pwm mailing list too (check To: line) - Should that driver portion really be in drivers/gpio or rather in drivers/pwm - Why is this not modeled as an MFD spawning a GPIO and a PWM cell, as is custom? (Bringing MFD maintainers into the picture.) So I am aware that this takes the problem from "quick fix extension to the GPIO driver" to "really nasty hairy re-engineering of the whole shebang" but there is a lot of precedents in the kernel for splitting up this type of hardware in separate drivers under an MFD hub. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-pwm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
