leds/powernv: Add driver for PowerNV platform

This patch implements LED driver for PowerNV platform using the existing
generic LED class framework.

PowerNV platform has below type of LEDs:
  - System attention
      Indicates there is a problem with the system that needs attention.
  - Identify
      Helps the user locate/identify a particular FRU or resource in the
      system.
  - Fault
      Indicates there is a problem with the FRU or resource at the
      location with which the indicator is associated.

We register classdev structures for all individual LEDs detected on the
system through LED specific device tree nodes. Device tree nodes specify
what all kind of LEDs present on the same location code. It registers
LED classdev structure for each of them.

All the system LEDs can be found in the same regular path /sys/class/leds/.
We don't use LED colors. We use LED node and led-types property to form
LED classdev. Our LEDs have names in this format.

        <location_code>:<attention|identify|fault>

Any positive brightness value would turn on the LED and a zero value would
turn off the LED. The driver will return LED_FULL (255) for any turned on
LED and LED_OFF (0) for any turned off LED.

The platform level implementation of LED get and set state has been
achieved through OPAL calls. These calls are made available for the
driver by exporting from architecture specific codes.

Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Acked-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Tested-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Acked-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 9ad35f72ab4c..f218cc3acc10 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -560,6 +560,17 @@ config LEDS_BLINKM
           This option enables support for the BlinkM RGB LED connected
           through I2C. Say Y to enable support for the BlinkM LED.
 
+config LEDS_POWERNV
+        tristate "LED support for PowerNV Platform"
+        depends on LEDS_CLASS
+        depends on PPC_POWERNV
+        depends on OF
+        help
+          This option enables support for the system LEDs present on
+          PowerNV platforms. Say 'y' to enable this support in kernel.
+          To compile this driver as a module, choose 'm' here: the module
+          will be called leds-powernv.
+
 config LEDS_SYSCON
         bool "LED support for LEDs on system controllers"
         depends on LEDS_CLASS=y