mfd: Add TI LMU driver

TI LMU (Lighting Management Unit) driver supports lighting devices below.

  LM3532, LM3631, LM3632, LM3633, LM3695 and LM3697.

LMU devices have common features.
  - I2C interface for accessing device registers
  - Hardware enable pin control
  - Backlight brightness control
  - Notifier for hardware fault monitoring
  - Regulators for LCD display bias

It contains fault monitor, backlight, LED and regulator driver.

LMU fault monitor
-----------------
  LM3633 and LM3697 provide hardware monitoring feature.
  It enables open or short circuit detection.
  After monitoring is done, each device should be re-initialized.
  Notifier is used for this case.
  Separate patch for 'ti-lmu-fault-monitor' will be sent later.

Backlight
---------
  It's handled by TI LMU backlight consolidated driver and
  chip dependent data. Separate patchset will be sent later.

LED indicator
-------------
  LM3633 has 6 indicator LEDs. Programmable dimming pattern is also
  supported. Separate patch for 'leds-lm3633' will be sent later.

Regulator
---------
  LM3631 has 5 regulators for the display bias.
  LM3632 supports 3 regulators. One consolidated driver enables it.
  The lm363x regulator driver is already upstreamed.

Signed-off-by: Milo Kim <milo.kim@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 8bbc91b..add0c35 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1181,6 +1181,18 @@
 	  TI LP8788 PMU supports regulators, battery charger, RTC,
 	  ADC, backlight driver and current sinks.
 
+config MFD_TI_LMU
+	tristate "TI Lighting Management Unit driver"
+	depends on I2C
+	select MFD_CORE
+	select REGMAP_I2C
+	help
+	  Say yes here to enable support for TI LMU chips.
+
+	  TI LMU MFD supports LM3532, LM3631, LM3632, LM3633, LM3695 and LM3697.
+	  It consists of backlight, LED and regulator driver.
+	  It provides consistent device controls for lighting functions.
+
 config MFD_OMAP_USB_HOST
 	bool "TI OMAP USBHS core and TLL driver"
 	depends on USB_EHCI_HCD_OMAP || USB_OHCI_HCD_OMAP3