[PATCH v10 0/3] LED driver for PowerNV platform

[Vasant Hegde <hegdevasant@linux.vnet.ibm.com>]

The following series implements LED driver for PowerNV platform.

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.

On PowerNV (Non Virtualized) platform OPAL firmware provides LED information
to host via device tree (location code and LED type). During init we check
for 'ibm,opal/leds' node in device tree to enable LED driver. And we use
OPAL API's to get/set LEDs.

Note that on PowerNV platform firmware can activate fault LED, if it can isolate
the problem. Also one can modify the LEDs using service processor interface. None
of these involes kernel. Hence we retain LED state in unload path.

Sample LED device tree output:
------------------------------
leds {
	compatible = "ibm,opal-v3-led";
	led-mode = "lightpath";

	U78C9.001.RST0027-P1-C1 {
		led-types = "identify", "fault";
	};
	...
	...
    }

Sample sysfs output:
--------------------
.
├── U78CB.001.WZS008R-A1:fault
│   ├── brightness
│   ├── device -> ../../../opal_leds
│   ├── max_brightness
│   ├── power
│   │   ├── async
│   │   ├── autosuspend_delay_ms
│   │   ├── control
│   │   ├── runtime_active_kids
│   │   ├── runtime_active_time
│   │   ├── runtime_enabled
│   │   ├── runtime_status
│   │   ├── runtime_suspended_time
│   │   └── runtime_usage
│   ├── subsystem -> ../../../../../class/leds
│   ├── trigger
│   └── uevent
├── U78CB.001.WZS008R-A1:identify
│   ├── brightness
│   ├── device -> ../../../opal_leds
│   ├── max_brightness
│   ├── power
│   │   ├── async
│   │   ├── autosuspend_delay_ms
│   │   ├── control
│   │   ├── runtime_active_kids
│   │   ├── runtime_active_time
│   │   ├── runtime_enabled
│   │   ├── runtime_status
│   │   ├── runtime_suspended_time
│   │   └── runtime_usage
│   ├── subsystem -> ../../../../../class/leds
│   ├── trigger
│   └── uevent
....
....
....

patch 1/2: PowerNV architecture specific code. This adds necessary
           OPAL APIs.
patch 2/2: Create LED platform device and export OPAL symbols
patch 3/3: Actual LED driver implemenation for PowerNV platform.

Note:
 - This version of patchset is based on top of v4.2-rc7.

@Ben/Michael,
  This patchset is Acked by LED subsystem maintainer (Jacek) [1] and he
  suggested merge it via powerpc tree [1]. Can you please review/take
  this patchset?

[1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-July/131695.html

Previous patchset:
  v9: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-August/132964.html
  v8: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-July/131652.html
  v7: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-July/131533.html
  v6: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-July/131328.html
  v5: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-July/130602.html
  v4: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-April/128028.html
  v3: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-April/127702.html
  v2: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-March/126301.html
  v1: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-March/125705.html

Changes in v10:
  - Removed "led_disabled" variable initialization
  - Removed ".owner = THIS_MODULE"

Changes in v9:
  - Addressed minor comments from Jacek.
  - Added Ack-by: Jacek

Changes in v8:
  - Added powernv_led_common structure for common variables
  - Removed unused variable 'value'
  - Fixed locking issue

Changes in v7:
  - Club powernv_led_data & powernv_leds_priv into single structure
  - Removed num_leds & powernv_leds_count()
  - Replaced per LED mutex with global mutex
  - Removed driver specific workqueue. Instead this version uses new
    global workqueue.

Changes in v6:
  - Added loc_code and type to powernv_led_data structure instead of parsing
    them from led classdev name.
  - Fixed documentation issues.
  - Fixed mutex_destry issue
  - Replaced led_classdev_register with devm_led_classdev_register

Changes in v5:
  - Rebased on top of Linus tree
  - Renamed led as leds and updated documentation
  - As Ben and Arnd suggested, removed phandle from documenation
  - As Ben suggested removed led-loc device tree property
  - As Jacek suggested, added back compatible property to documentation

Changes in v4:
  - Updated macros to reflect platform.
  - s/u64/__be64/g for big endian data we get from firmware
  - Addressed review comments from Jacek. Major once are:
    Removed list in powernv_led_data structure
    s/kzalloc/devm_kzalloc/
    Removed compatible property from documentation


Anshuman Khandual (1):
  powerpc/powernv: Add OPAL interfaces for accessing and modifying
    system LED states

Vasant Hegde (2):
  powerpc/powernv: Create LED platform device
  leds/powernv: Add driver for PowerNV platform

 .../devicetree/bindings/leds/leds-powernv.txt      |  26 ++
 arch/powerpc/include/asm/opal-api.h                |  25 +-
 arch/powerpc/include/asm/opal.h                    |   4 +
 arch/powerpc/platforms/powernv/opal-wrappers.S     |   2 +
 arch/powerpc/platforms/powernv/opal.c              |  12 +-
 drivers/leds/Kconfig                               |  11 +
 drivers/leds/Makefile                              |   1 +
 drivers/leds/leds-powernv.c                        | 345 +++++++++++++++++++++
 8 files changed, 424 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-powernv.txt
 create mode 100644 drivers/leds/leds-powernv.c

-- 
Vasant
2.1.0