pwm PXA: Compile only on PXA ...

The PXA PWM driver does not compile on any other architecture, so
depend on PXA.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/pwm: add PXA pulse width modulator controller ...

Add PXA embedded pulse width modulator support. The PWM can
generate signals from 49.6kHz to 1.625MHz.
The driver is for pxa2xx family. The pxa3xx was not handled yet.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/pwm: add duty_ns and period_ns to core pwm chip ...

Add variables to control the duty_ns and period_ns of PWM
chips. When these variables are set, a call to either
pwm_enable() or pwm_config() is performed to enforce the
setup values.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Add pwm core support ...

This patch adds framework support for PWM (pulse width modulation)
devices.
A new pwm can be registered from a hardware driver using
pwmchip_add(). It can then be requested from a client driver using
pwm_request(). A string is used as a unique identifier for the
pwms. It should usually be initialized by the hardware drivers
using dev_name(dev). The client API is the same as currently
in the Linux Kernel.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>