pwm: Add PWM driver for OMAP using dual-mode timers

Adds support for using a OMAP dual-mode timer with PWM capability
as a Linux PWM device. The driver controls the timer by using the
dmtimer API.

Add a platform_data structure for each pwm-omap-dmtimer nodes containing
the dmtimers functions in order to get driver not rely on platform
specific functions.

Cc: Grant Erickson <marathon96@gmail.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Joachim Eastwood <manabian@gmail.com>
Suggested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Tony Lindgren <tony@atomide.com>
[thierry.reding@gmail.com: coding style bikeshed, fix timer leak]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/Kconfig

@@ -265,6 +265,15 @@ config PWM_MXS
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-mxs.
 
+config PWM_OMAP_DMTIMER
+	tristate "OMAP Dual-Mode Timer PWM support"
+	depends on OF && ARCH_OMAP && OMAP_DM_TIMER
+	help
+	  Generic PWM framework driver for OMAP Dual-Mode Timer PWM output
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-omap-dmtimer
+
 config PWM_PCA9685
 	tristate "NXP PCA9685 PWM driver"
 	depends on I2C