Re: [PATCH v3 3/3] leds/powernv: Add driver for PowerNV platform

Re: [PATCH v3 3/3] leds/powernv: Add driver for PowerNV platform

[Jacek Anaszewski]

> On 21.04.2015 07:50, Vasant Hegde wrote:
> On 04/20/2015 08:57 PM, Jacek Anaszewski wrote:
>> Hi Vasant,
>>
> 
> Jacek,
> 
> Thanks for the review.

You are welcome.

>> Thanks for the update.
>>
>> On 04/20/2015 10:01 AM, Vasant Hegde wrote:
>>> 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 registers classdev structures for all individual LEDs detected
>>> on the
>>
>> s/registers/register
> 
> Fixed.
> 
>>
>>> 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. Hence our LEDs have
>>> names in this format.
>>>
>>>           <location_code>:<ATTENTION|IDENT|FAULT>
>>
>> I think that powernv prefix should be also present in the beginning.
>> What would be the format of <location_code> ? Does it identify a LED
>> uniquely.
> 
> Location code is unique and its guaranteed that we don't clash here.
> Also this is platform specific LEDs and I don't see any value by
> prefixing "powernv". Hence I think its fine with current format.
> 
> Sample location code : U78C9.001.RST0027-P1-C1
>    Here "U78C9.001.RST0027" represents the system model
>               P1 - Planar 1
>               C1 - Card 1

I consulted ePAPR standard and all the characters used for location code
are allowed. Nonetheless AFAIK no existing bindings use uppercase for
node name.


We will need DT maintainer's ack here too, so cc DT list.
Please CC devicetree@vger.kernel.org next time, especially for
DT documentation patch.

> .../...
> 
>>> +led {
>>> +    compatible = "ibm,opal-v3-led";
>>> +    phandle = <0x1000006b>;
>>> +    linux,phandle = <0x1000006b>;
>>> +    led-mode = "lightpath";
>>> +
>>> +    U78C9.001.RST0027-P1-C1 {
>>
>> DT node names should be in lowercase form.
>> Is U78C9.001.RST0027-P1-C1 a location code?
> 
> Yes ... Node presents the location code.. Platform provides these
> location code in upper case. Hence our OPAL firmware exposes them in
> upper case.
> 
>>
>>> +        led-types = "identify", "fault";
>>> +        led-loc = "descendent";
>>> +        phandle = <0x1000006f>;
>>> +        linux,phandle = <0x1000006f>;

I think that all these properties will not be needed.

>>> +    };
>>> +    ...
>>> +    ...
>>> +};
>>> +
>>> +
>>> +'compatible' property describes LEDs compatibility.
>>
>> compatible doesn't need to be mentioned here.
> 
> Removed.
> 
>>
>>> +'led-mode' property describes service indicator mode
>>> (lightpath/guidinglight).
>>
>> You don't parse this in the driver? What is its purpose?
> 
> As mentioned in other thread, currently our driver doesn't parse
> this. (As mode is provided by platform and its static).
> 
> Do you want me to elaborate this property here?

I don't think so. At least for now :)

> .../...
> 
>>> +
>>> +/*
>>> + * By default unload path resets all the LEDs. But on PowerNV
>>> platform
>>> + * we want to retain LED state across reboot as these are
>>> controlled by
>>> + * firmware. Also service processor can modify the LEDs
>>> independent of
>>> + * OS. Hence avoid resetting LEDs in unload path.
>>> + */
>>> +static bool led_disabled;
>>
>> I think that we have to make it configurable from the Device Tree
>> level. There could be a 'retain-state-removed' property introduced.
> 
> Hmmm.. In my case, LED behavior is not going to change. Hence I don't
> think we need this property.

Can you guarantee that the next version of the platform will have also
the same requirements? What if it would be made available to choose
that the LEDs are software-only controlled?

If these are unjustified doubts, I'm ok with leaving the static
variable.

>>
>> There is also another implication - you define LED_CORE_SUSPENDRESUME
>> flag. With current approach it wouldn't turn the led off on suspend.
>> Please either drop the flag or assure correct behaviour on suspend.
> 
> I will drop this.
> 
>> You can also make this configurable like retain-state-suspended
>> property in Documentation/devicetree/bindings/leds/leds-gpio.txt.
>>
> 
> .../...
> 
>>> +
>>> +    if (powernv_get_loc_code(led_type, loc_code) != 0)
>>> +        goto out_loc;
>>> +
>>> +    /* Prepare for the OPAL call */
>>> +    max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
>>> +    led_mask = OPAL_SLOT_LED_STATE_ON << led_type;
>>> +    if (value)
>>> +        led_value = OPAL_SLOT_LED_STATE_ON << led_type;
>>
>>          led_value = led_mask;
> 
> Fixed.
> 
> .../...
> 
>>> +
>>> +/* Schedule work to update LED state */
>>> +static void powernv_led_set_queue(struct led_classdev *led_cdev,
>>> +                  enum led_brightness value, u64 led_type)
>>
>> It doesn't set any queue. It should be powernv_brightness_set.
> 
> Make sense. Fixed.
> 
> .../...
> 
>>> +    /* Create the name for classdev */
>>> +    switch (led_type) {
>>> +    case OPAL_SLOT_LED_TYPE_ATTN:
>>> +        powernv_led->cdev.name = kasprintf(GFP_KERNEL,
>>> +                           "%s%s", node->name,
>>> +                           POWERNV_LED_ATTN);
>>
>> LED name should be taken from of_node name or label property
>> directly. Please refer to the other LED class drivers.
> 
> Hmmm.. Our  current FW provides led-types property which tells
> available type for given location code..
> like
>    led-types = "identify" "fault"..
> 
> Can I use this ? So the names will be
>     <location_code>:<identify|fault|attention>

I adressed this in the other message.

> And if this approach fine,  I can fix (assuming maintainer agrees :-)
> ) firmware side to change identify -> ident.

Let's leave it. It seems to be platform specific.


-- 
Best Regards,
Jacek Anaszewski

Re: [PATCH v3 3/3] leds/powernv: Add driver for PowerNV platform

[Vasant Hegde]

On 04/23/2015 03:15 AM, Jacek Anaszewski wrote:
>> On 21.04.2015 07:50, Vasant Hegde wrote:
>> On 04/20/2015 08:57 PM, Jacek Anaszewski wrote:
>>> Hi Vasant,
>>>
>>

Jacek,

.../...

>>>>
>>>> All the system LEDs can be found in the same regular
>>>> path /sys/class/leds/. We don't use LED colors. Hence our LEDs have
>>>> names in this format.
>>>>
>>>>           <location_code>:<ATTENTION|IDENT|FAULT>
>>>
>>> I think that powernv prefix should be also present in the beginning.
>>> What would be the format of <location_code> ? Does it identify a LED
>>> uniquely.
>>
>> Location code is unique and its guaranteed that we don't clash here.
>> Also this is platform specific LEDs and I don't see any value by
>> prefixing "powernv". Hence I think its fine with current format.
>>
>> Sample location code : U78C9.001.RST0027-P1-C1
>>    Here "U78C9.001.RST0027" represents the system model
>>               P1 - Planar 1
>>               C1 - Card 1
> 
> I consulted ePAPR standard and all the characters used for location code
> are allowed. Nonetheless AFAIK no existing bindings use uppercase for
> node name.
> 

These are PowerNV platform specific properties..


> 
> We will need DT maintainer's ack here too, so cc DT list.
> Please CC devicetree@vger.kernel.org next time, especially for
> DT documentation patch.
> 

Sure. Next time I will CC DT mailing list.

@Ben,
  Any comments?

>> .../...
>>
>>>> +led {
>>>> +    compatible = "ibm,opal-v3-led";
>>>> +    phandle = <0x1000006b>;
>>>> +    linux,phandle = <0x1000006b>;
>>>> +    led-mode = "lightpath";
>>>> +
>>>> +    U78C9.001.RST0027-P1-C1 {
>>>
>>> DT node names should be in lowercase form.
>>> Is U78C9.001.RST0027-P1-C1 a location code?
>>
>> Yes ... Node presents the location code.. Platform provides these
>> location code in upper case. Hence our OPAL firmware exposes them in
>> upper case.
>>
>>>
>>>> +        led-types = "identify", "fault";
>>>> +        led-loc = "descendent";
>>>> +        phandle = <0x1000006f>;
>>>> +        linux,phandle = <0x1000006f>;
> 
> I think that all these properties will not be needed.

These properties are coming from our firmware which is static.

phandle property is default .. which is required to uniquely identify node
inside  DT.
led-loc property is not used today. If its not going to be used forever then I
can request
FW folks to remove it later.


> 
>>>> +    };
>>>> +    ...
>>>> +    ...
>>>> +};
>>>> +
>>>> +
>>>> +'compatible' property describes LEDs compatibility.
>>>
>>> compatible doesn't need to be mentioned here.
>>
>> Removed.
>>
>>>
>>>> +'led-mode' property describes service indicator mode
>>>> (lightpath/guidinglight).
>>>
>>> You don't parse this in the driver? What is its purpose?
>>
>> As mentioned in other thread, currently our driver doesn't parse
>> this. (As mode is provided by platform and its static).
>>
>> Do you want me to elaborate this property here?
> 
> I don't think so. At least for now :)

Ok.

> 
>> .../...
>>
>>>> +
>>>> +/*
>>>> + * By default unload path resets all the LEDs. But on PowerNV
>>>> platform
>>>> + * we want to retain LED state across reboot as these are
>>>> controlled by
>>>> + * firmware. Also service processor can modify the LEDs
>>>> independent of
>>>> + * OS. Hence avoid resetting LEDs in unload path.
>>>> + */
>>>> +static bool led_disabled;
>>>
>>> I think that we have to make it configurable from the Device Tree
>>> level. There could be a 'retain-state-removed' property introduced.
>>
>> Hmmm.. In my case, LED behavior is not going to change. Hence I don't
>> think we need this property.
> 
> Can you guarantee that the next version of the platform will have also
> the same requirements? What if it would be made available to choose
> that the LEDs are software-only controlled?

This design exists for ages.. IMO if we change this to software control (or
dynamic property which can be changed during runtime) then it completely defeats
the LED purpose. Hence I don't think it will change anytime.

> 
> If these are unjustified doubts, I'm ok with leaving the static
> variable.
> 
>>>
>>> There is also another implication - you define LED_CORE_SUSPENDRESUME
>>> flag. With current approach it wouldn't turn the led off on suspend.
>>> Please either drop the flag or assure correct behaviour on suspend.
>>
>> I will drop this.
>>
>>> You can also make this configurable like retain-state-suspended
>>> property in Documentation/devicetree/bindings/leds/leds-gpio.txt.
>>>
>>
>> .../...
>>
>>>> +
>>>> +    if (powernv_get_loc_code(led_type, loc_code) != 0)
>>>> +        goto out_loc;
>>>> +
>>>> +    /* Prepare for the OPAL call */
>>>> +    max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
>>>> +    led_mask = OPAL_SLOT_LED_STATE_ON << led_type;
>>>> +    if (value)
>>>> +        led_value = OPAL_SLOT_LED_STATE_ON << led_type;
>>>
>>>          led_value = led_mask;
>>
>> Fixed.
>>
>> .../...
>>
>>>> +
>>>> +/* Schedule work to update LED state */
>>>> +static void powernv_led_set_queue(struct led_classdev *led_cdev,
>>>> +                  enum led_brightness value, u64 led_type)
>>>
>>> It doesn't set any queue. It should be powernv_brightness_set.
>>
>> Make sense. Fixed.
>>
>> .../...
>>
>>>> +    /* Create the name for classdev */
>>>> +    switch (led_type) {
>>>> +    case OPAL_SLOT_LED_TYPE_ATTN:
>>>> +        powernv_led->cdev.name = kasprintf(GFP_KERNEL,
>>>> +                           "%s%s", node->name,
>>>> +                           POWERNV_LED_ATTN);
>>>
>>> LED name should be taken from of_node name or label property
>>> directly. Please refer to the other LED class drivers.
>>
>> Hmmm.. Our  current FW provides led-types property which tells
>> available type for given location code..
>> like
>>    led-types = "identify" "fault"..
>>
>> Can I use this ? So the names will be
>>     <location_code>:<identify|fault|attention>
> 
> I adressed this in the other message.
> 
>> And if this approach fine,  I can fix (assuming maintainer agrees :-)
>> ) firmware side to change identify -> ident.
> 
> Let's leave it. It seems to be platform specific.

Sure.

Thanks!
-Vasant

[PATCH v3 0/3] LED interface for PowerNV platform

[Vasant Hegde]

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/led' 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:
------------------------------
led {
	compatible = "ibm,opal-v3-led";
	phandle = <0x1000006b>;
	linux,phandle = <0x1000006b>;
	led-mode = "lightpath";

	U78C9.001.RST0027-P1-C1 {
		led-types = "identify", "fault";
		led-loc = "descendent";
		phandle = <0x1000006f>;
		linux,phandle = <0x1000006f>;
	};
	...
	...
    }

Sample sysfs output:
--------------------
.
├── U78CB.001.WZS008R-A1:FAULT
│   ├── brightness
│   ├── device -> ../../../opal_led
│   ├── 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:IDENT
│   ├── brightness
│   ├── device -> ../../../opal_led
│   ├── 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.

This patchset is based on top of mpe's next branch:
  https://git.kernel.org/cgit/linux/kernel/git/mpe/linux.git/log/?h=next

Previous patchset:
  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 v3:
  - Addressed review comments from Jacek. Major once are:
    Replaced spin lock and mutex and removed redundant structures
    Replaced pr_* with dev_*
    Moved OPAL platform sepcific part to separate patch
    Moved repteated code to common function
    Added device tree documentation for LEDs

Changes in v2:
  - Rebased patches on top of mpe's next branch
    https://git.kernel.org/cgit/linux/kernel/git/mpe/linux.git/log/?h=next
  - Added System Attention Indicator support
  - Removed redundant code in leds-powernv.c file


---

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      |   34 +
 arch/powerpc/include/asm/opal-api.h                |   29 +
 arch/powerpc/include/asm/opal.h                    |    5 
 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                        |  455 ++++++++++++++++++++
 8 files changed, 547 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-powernv.txt
 create mode 100644 drivers/leds/leds-powernv.c

--
Vasant

[PATCH v3 3/3] leds/powernv: Add driver for PowerNV platform

[Vasant Hegde]

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 registers 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. Hence our LEDs have names in this format.

        <location_code>:<ATTENTION|IDENT|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.

As per the LED class framework, the 'brightness_set' function should not
sleep. Hence these functions have been implemented through global work
queue tasks which might sleep on OPAL async call completion.

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>

---
Changes in v3:
  - Addressed review comments from Jacek. Major once are:
    Replaced spin lock and mutex and removed redundant structures
    Replaced pr_* with dev_*
    Moved OPAL platform sepcific part to separate patch
    Moved repteated code to common function
    Added device tree documentation for LEDs

Changes in v2:
  - Added System Attention indicator support
  - Moved common code to powernv_led_set_queue()

 .../devicetree/bindings/leds/leds-powernv.txt      |   34 +
 drivers/leds/Kconfig                               |   11 
 drivers/leds/Makefile                              |    1 
 drivers/leds/leds-powernv.c                        |  455 ++++++++++++++++++++
 4 files changed, 501 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-powernv.txt
 create mode 100644 drivers/leds/leds-powernv.c

diff --git a/Documentation/devicetree/bindings/leds/leds-powernv.txt b/Documentation/devicetree/bindings/leds/leds-powernv.txt
new file mode 100644
index 0000000..4953fdf
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-powernv.txt
@@ -0,0 +1,34 @@
+Device Tree binding for LEDs on IBM Power Systems
+-------------------------------------------------
+
+The 'led' node under '/ibm,opal' lists service indicators available in the
+system and their capabilities.
+
+led {
+	compatible = "ibm,opal-v3-led";
+	phandle = <0x1000006b>;
+	linux,phandle = <0x1000006b>;
+	led-mode = "lightpath";
+
+	U78C9.001.RST0027-P1-C1 {
+		led-types = "identify", "fault";
+		led-loc = "descendent";
+		phandle = <0x1000006f>;
+		linux,phandle = <0x1000006f>;
+	};
+	...
+	...
+};
+
+
+'compatible' property describes LEDs compatibility.
+
+'led-mode' property describes service indicator mode (lightpath/guidinglight).
+
+Each node under 'led' node describes location code of FRU/Enclosure.
+
+The properties under each node:
+
+  led-types : Supported indicators (attention/identify/fault).
+
+  led-loc   : enclosure/descendent(FRU) location code.
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 25b320d..2ea0849 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -508,6 +508,17 @@ 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
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index cbba921..604ffc9 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_LEDS_BLINKM)		+= leds-blinkm.o
 obj-$(CONFIG_LEDS_SYSCON)		+= leds-syscon.o
 obj-$(CONFIG_LEDS_VERSATILE)		+= leds-versatile.o
 obj-$(CONFIG_LEDS_MENF21BMC)		+= leds-menf21bmc.o
+obj-$(CONFIG_LEDS_POWERNV)		+= leds-powernv.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
diff --git a/drivers/leds/leds-powernv.c b/drivers/leds/leds-powernv.c
new file mode 100644
index 0000000..e3c033d
--- /dev/null
+++ b/drivers/leds/leds-powernv.c
@@ -0,0 +1,455 @@
+/*
+ * PowerNV LED Driver
+ *
+ * Copyright IBM Corp. 2015
+ *
+ * Author: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
+ * Author: Anshuman Khandual <khandual@linux.vnet.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define PREFIX		"POWERNV_LED"
+
+#include <linux/leds.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <asm/opal.h>
+
+#define POWERNV_LED_ATTN	":ATTENTION"
+#define POWERNV_LED_IDENT	":IDENT"
+#define POWERNV_LED_FAULT	":FAULT"
+
+/*
+ * By default unload path resets all the LEDs. But on PowerNV platform
+ * we want to retain LED state across reboot as these are controlled by
+ * firmware. Also service processor can modify the LEDs independent of
+ * OS. Hence avoid resetting LEDs in unload path.
+ */
+static bool led_disabled;
+
+/* Converts LED event type into it's description. */
+static const char *led_type_map[OPAL_SLOT_LED_TYPE_MAX] = {
+	"Attention", "Ident", "Fault"
+};
+
+/*
+ * LED set routines have been implemented as work queue tasks scheduled
+ * on the global work queue. Individual task calls OPAL interface to set
+ * the LED state which might sleep for some time.
+ */
+struct powernv_led_data {
+	struct led_classdev	cdev;
+
+	u64			led_type;  /* Attention or Ident or Fault */
+	enum led_brightness	value;     /* Brightness value */
+
+	struct mutex		lock;
+	struct work_struct	work_led; /* LED update workqueue */
+
+	struct list_head	link;
+};
+static LIST_HEAD(powernv_led_list);
+
+
+/* Get LED location code based on LED name */
+static int powernv_get_loc_code(u64 led_type, char *loc_code)
+{
+	switch (led_type) {
+	case OPAL_SLOT_LED_TYPE_ATTN:
+		loc_code[strlen(loc_code) - strlen(POWERNV_LED_ATTN)] = '\0';
+		break;
+	case OPAL_SLOT_LED_TYPE_ID:
+		loc_code[strlen(loc_code) - strlen(POWERNV_LED_IDENT)] = '\0';
+		break;
+	case OPAL_SLOT_LED_TYPE_FAULT:
+		loc_code[strlen(loc_code) - strlen(POWERNV_LED_FAULT)] = '\0';
+		break;
+	default:	/* Unsupported LED type */
+		return -1;
+	}
+	return 0;
+}
+
+/*
+ * This commits the state change of the requested LED through an OPAL call.
+ * This function is called from work queue task context when ever it gets
+ * scheduled. This function can sleep at opal_async_wait_response call.
+ */
+static void powernv_led_set(struct led_classdev *led_cdev,
+			    enum led_brightness value, u64 led_type)
+{
+	char *loc_code;
+	int rc, token;
+	u64 led_mask, max_led_type, led_value = 0;
+	struct opal_msg msg;
+
+	/* Location code of the LED */
+	loc_code = kasprintf(GFP_KERNEL, "%s", led_cdev->name);
+	if (!loc_code) {
+		dev_err(led_cdev->dev,
+			"%s: Memory allocation failed\n", __func__);
+		return;
+	}
+
+	if (powernv_get_loc_code(led_type, loc_code) != 0)
+		goto out_loc;
+
+	/* Prepare for the OPAL call */
+	max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
+	led_mask = OPAL_SLOT_LED_STATE_ON << led_type;
+	if (value)
+		led_value = OPAL_SLOT_LED_STATE_ON << led_type;
+
+	/* OPAL async call */
+	token = opal_async_get_token_interruptible();
+	if (token < 0) {
+		if (token != -ERESTARTSYS)
+			dev_err(led_cdev->dev,
+				"%s: Couldn't get OPAL async token\n",
+				__func__);
+		goto out_loc;
+	}
+
+	rc = opal_leds_set_ind(token, loc_code,
+			       led_mask, led_value, &max_led_type);
+	if (rc != OPAL_ASYNC_COMPLETION) {
+		dev_err(led_cdev->dev,
+			"%s: OPAL set LED call failed for %s [rc=%d]\n",
+			__func__, loc_code, rc);
+		goto out_token;
+	}
+
+	rc = opal_async_wait_response(token, &msg);
+	if (rc) {
+		dev_err(led_cdev->dev,
+			"%s: Failed to wait for the async response [rc=%d]\n",
+			__func__, rc);
+		goto out_token;
+	}
+
+	rc = be64_to_cpu(msg.params[1]);
+	if (rc != OPAL_SUCCESS)
+		dev_err(led_cdev->dev,
+			"%s : OAPL async call returned failed [rc=%d]\n",
+			__func__, rc);
+
+out_token:
+	opal_async_release_token(token);
+
+out_loc:
+	kfree(loc_code);
+}
+
+/*
+ * This function fetches the LED state for a given LED type for
+ * mentioned LED classdev structure.
+ */
+static enum led_brightness powernv_led_get(struct led_classdev *led_cdev,
+					   u64 led_type)
+{
+	char *loc_code;
+	int rc;
+	u64 led_mask, led_value, max_led_type;
+
+	/* LED location code */
+	loc_code = kasprintf(GFP_KERNEL, "%s", led_cdev->name);
+	if (!loc_code) {
+		dev_err(led_cdev->dev,
+			"%s: Memory allocation failed\n", __func__);
+		return -ENOMEM;
+	}
+
+	if (powernv_get_loc_code(led_type, loc_code) != 0)
+		goto led_fail;
+
+	/* Fetch all LED status */
+	led_mask = cpu_to_be64(0);
+	led_value = cpu_to_be64(0);
+	max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
+
+	rc = opal_leds_get_ind(loc_code, &led_mask, &led_value, &max_led_type);
+	if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
+		dev_err(led_cdev->dev,
+			"%s: OPAL get led call failed [rc=%d]\n",
+			__func__, rc);
+		goto led_fail;
+	}
+
+	led_mask = be64_to_cpu(led_mask);
+	led_value = be64_to_cpu(led_value);
+
+	/* LED status available */
+	if (!((led_mask >> led_type) & OPAL_SLOT_LED_STATE_ON)) {
+		dev_err(led_cdev->dev,
+			"%s: %s LED status not available for %s\n",
+			__func__, led_type_map[led_type], loc_code);
+		goto led_fail;
+	}
+
+	/* LED status value */
+	if ((led_value >> led_type) & OPAL_SLOT_LED_STATE_ON) {
+		kfree(loc_code);
+		return LED_FULL;
+	}
+
+led_fail:
+	kfree(loc_code);
+	return LED_OFF;
+}
+
+/*
+ * This the function which will be executed by any LED work task on the
+ * global work queue.
+ */
+static void powernv_deferred_led_set(struct work_struct *work)
+{
+	struct powernv_led_data *powernv_led =
+		container_of(work, struct powernv_led_data, work_led);
+
+	mutex_lock(&powernv_led->lock);
+	powernv_led_set(&powernv_led->cdev,
+			powernv_led->value, powernv_led->led_type);
+	mutex_unlock(&powernv_led->lock);
+}
+
+/* Schedule work to update LED state */
+static void powernv_led_set_queue(struct led_classdev *led_cdev,
+				  enum led_brightness value, u64 led_type)
+{
+	struct powernv_led_data *powernv_led =
+		container_of(led_cdev, struct powernv_led_data, cdev);
+
+	/* Do not modify LED in unload path */
+	if (led_disabled)
+		return;
+
+	/* Prepare the request */
+	powernv_led->value = value;
+	powernv_led->led_type = led_type;
+
+	/* Schedule the new task */
+	schedule_work(&powernv_led->work_led);
+}
+
+
+/* LED classdev 'brightness_set' function for attention LED. */
+static void powernv_led_set_attn(struct led_classdev *led_cdev,
+				  enum led_brightness value)
+{
+	return powernv_led_set_queue(led_cdev, value, OPAL_SLOT_LED_TYPE_ATTN);
+}
+
+/* LED classdev 'brightness_get' function for attention LED.  */
+static enum led_brightness powernv_led_get_attn(struct led_classdev *led_cdev)
+{
+	return powernv_led_get(led_cdev, OPAL_SLOT_LED_TYPE_ATTN);
+}
+
+/* LED classdev 'brightness_set' function for ident LED types. */
+static void powernv_led_set_ident(struct led_classdev *led_cdev,
+				  enum led_brightness value)
+{
+	return powernv_led_set_queue(led_cdev, value, OPAL_SLOT_LED_TYPE_ID);
+}
+
+/* LED classdev 'brightness_get' function for ident LED types. */
+static enum led_brightness powernv_led_get_ident(struct led_classdev *led_cdev)
+{
+	return powernv_led_get(led_cdev, OPAL_SLOT_LED_TYPE_ID);
+}
+
+/* LED classdev 'brightness_set' function for fault LED types. */
+static void powernv_led_set_fault(struct led_classdev *led_cdev,
+				  enum led_brightness value)
+{
+	return powernv_led_set_queue(led_cdev, value, OPAL_SLOT_LED_TYPE_FAULT);
+}
+
+/* LED classdev 'brightness_get' function for fault LED types. */
+static enum led_brightness powernv_led_get_fault(struct led_classdev *led_cdev)
+{
+	return powernv_led_get(led_cdev, OPAL_SLOT_LED_TYPE_FAULT);
+}
+
+
+/*
+ * This function verifies whether the child LED device node supports certain
+ * type of LED or not. This will be used to register LED classdev structures
+ * for that particual type of LED for a given device tree node.
+ */
+static bool has_led_type(struct device_node *node, const char *led_type)
+{
+	bool result = false;
+
+	if (of_property_match_string(node, "led-types", led_type) >= 0)
+		result = true;
+
+	return result;
+}
+
+/*
+ * This function registers classdev structure for any given type of LED on
+ * a given child LED device node.
+ */
+static int power_led_classdev(struct platform_device *pdev,
+			      struct device_node *node, u64 led_type)
+{
+	int rc;
+	struct powernv_led_data *powernv_led;
+
+	powernv_led = kzalloc(sizeof(struct powernv_led_data), GFP_KERNEL);
+	if (!powernv_led) {
+		dev_err(&pdev->dev,
+			"%s: Memory allocation failed\n", __func__);
+		return -ENOMEM;
+	}
+
+	/* Create the name for classdev */
+	switch (led_type) {
+	case OPAL_SLOT_LED_TYPE_ATTN:
+		powernv_led->cdev.name = kasprintf(GFP_KERNEL,
+						   "%s%s", node->name,
+						   POWERNV_LED_ATTN);
+		powernv_led->cdev.brightness_set = powernv_led_set_attn;
+		powernv_led->cdev.brightness_get = powernv_led_get_attn;
+		break;
+	case OPAL_SLOT_LED_TYPE_ID:
+		powernv_led->cdev.name = kasprintf(GFP_KERNEL,
+						   "%s%s", node->name,
+						   POWERNV_LED_IDENT);
+		powernv_led->cdev.brightness_set = powernv_led_set_ident;
+		powernv_led->cdev.brightness_get = powernv_led_get_ident;
+		break;
+	case OPAL_SLOT_LED_TYPE_FAULT:
+		powernv_led->cdev.name = kasprintf(GFP_KERNEL,
+						   "%s%s", node->name,
+						   POWERNV_LED_FAULT);
+		powernv_led->cdev.brightness_set = powernv_led_set_fault;
+		powernv_led->cdev.brightness_get = powernv_led_get_fault;
+		break;
+	default: /* Unsupported LED type */
+		kfree(powernv_led);
+		return -EINVAL;
+	}
+
+	if (!powernv_led->cdev.name) {
+		dev_err(&pdev->dev,
+			"%s: Memory allocation failed for classdev name\n",
+			__func__);
+		kfree(powernv_led);
+		return -ENOMEM;
+	}
+
+	powernv_led->cdev.brightness = LED_OFF;
+	powernv_led->cdev.max_brightness = LED_FULL;
+	powernv_led->cdev.flags = LED_CORE_SUSPENDRESUME;
+
+	mutex_init(&powernv_led->lock);
+	INIT_WORK(&powernv_led->work_led, powernv_deferred_led_set);
+
+	/* Register the classdev */
+	rc = led_classdev_register(&pdev->dev, &powernv_led->cdev);
+	if (rc) {
+		dev_err(&pdev->dev, "%s: Classdev registration failed for %s\n",
+			__func__, powernv_led->cdev.name);
+		kfree(powernv_led->cdev.name);
+		kfree(powernv_led);
+	} else {
+		list_add_tail(&powernv_led->link, &powernv_led_list);
+		dev_dbg(&pdev->dev,
+			"Classdev registration successful for %s\n",
+			powernv_led->cdev.name);
+	}
+	return rc;
+}
+
+/* Platform driver probe */
+static int powernv_led_probe(struct platform_device *pdev)
+{
+	int rc = 0;
+	struct device_node *led_node, *np;
+
+	led_node = of_find_node_by_path("/ibm,opal/led");
+	if (!led_node) {
+		dev_err(&pdev->dev,
+			"%s: LED parent device node not found\n", __func__);
+		return -EINVAL;
+	}
+
+	for_each_child_of_node(led_node, np) {
+		if (has_led_type(np, LED_TYPE_ATTENTION))
+			rc = power_led_classdev(pdev, np,
+						OPAL_SLOT_LED_TYPE_ATTN);
+
+		if (has_led_type(np, LED_TYPE_IDENTIFY))
+			rc = power_led_classdev(pdev, np,
+						OPAL_SLOT_LED_TYPE_ID);
+
+		if (has_led_type(np, LED_TYPE_FAULT))
+			rc = power_led_classdev(pdev, np,
+						OPAL_SLOT_LED_TYPE_FAULT);
+	}
+	return rc;
+}
+
+/* Platform driver remove */
+static int powernv_led_remove(struct platform_device *pdev)
+{
+	struct powernv_led_data *powernv_led;
+
+	/* Disable LED operation */
+	led_disabled = true;
+
+	dev_dbg(&pdev->dev,
+		"%s: Unregister all classdev structures\n", __func__);
+	list_for_each_entry(powernv_led, &powernv_led_list, link)
+		led_classdev_unregister(&powernv_led->cdev);
+
+	dev_dbg(&pdev->dev,
+		"%s: Wait for all work tasks to finish\n", __func__);
+	list_for_each_entry(powernv_led, &powernv_led_list, link)
+		flush_work(&powernv_led->work_led);
+
+	while (!list_empty(&powernv_led_list)) {
+		powernv_led = list_first_entry(&powernv_led_list,
+					       struct powernv_led_data, link);
+		list_del(&powernv_led->link);
+		kfree(powernv_led);
+	}
+
+	dev_info(&pdev->dev, "PowerNV led module unregistered\n");
+	return 0;
+}
+
+/* Platform driver property match */
+static const struct of_device_id powernv_led_match[] = {
+	{
+		.compatible	= "ibm,opal-v3-led",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, powernv_led_match);
+
+static struct platform_driver powernv_led_driver = {
+	.probe	= powernv_led_probe,
+	.remove = powernv_led_remove,
+	.driver = {
+		.name = "powernv-led-driver",
+		.owner = THIS_MODULE,
+		.of_match_table = powernv_led_match,
+	},
+};
+
+module_platform_driver(powernv_led_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("PowerNV LED driver");
+MODULE_AUTHOR("Vasant Hegde <hegdevasant@linux.vnet.ibm.com>");

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Re: [PATCH v3 3/3] leds/powernv: Add driver for PowerNV platform

[Jacek Anaszewski]

Hi Vasant,

Thanks for the update.

On 04/20/2015 10:01 AM, Vasant Hegde wrote:
> 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 registers classdev structures for all individual LEDs detected on the

s/registers/register

> 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. Hence our LEDs have names in this format.
>
>          <location_code>:<ATTENTION|IDENT|FAULT>

I think that powernv prefix should be also present in the beginning.
What would be the format of <location_code> ? Does it identify a LED
uniquely.

>
> 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.
>
> As per the LED class framework, the 'brightness_set' function should not
> sleep. Hence these functions have been implemented through global work
> queue tasks which might sleep on OPAL async call completion.
>
> 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>
>
> ---
> Changes in v3:
>    - Addressed review comments from Jacek. Major once are:
>      Replaced spin lock and mutex and removed redundant structures
>      Replaced pr_* with dev_*
>      Moved OPAL platform sepcific part to separate patch
>      Moved repteated code to common function
>      Added device tree documentation for LEDs
>
> Changes in v2:
>    - Added System Attention indicator support
>    - Moved common code to powernv_led_set_queue()
>
>   .../devicetree/bindings/leds/leds-powernv.txt      |   34 +
>   drivers/leds/Kconfig                               |   11
>   drivers/leds/Makefile                              |    1
>   drivers/leds/leds-powernv.c                        |  455 ++++++++++++++++++++
>   4 files changed, 501 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/leds/leds-powernv.txt
>   create mode 100644 drivers/leds/leds-powernv.c
>
> diff --git a/Documentation/devicetree/bindings/leds/leds-powernv.txt b/Documentation/devicetree/bindings/leds/leds-powernv.txt
> new file mode 100644
> index 0000000..4953fdf
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/leds-powernv.txt
> @@ -0,0 +1,34 @@
> +Device Tree binding for LEDs on IBM Power Systems
> +-------------------------------------------------
> +
> +The 'led' node under '/ibm,opal' lists service indicators available in the
> +system and their capabilities.
> +
> +led {
> +	compatible = "ibm,opal-v3-led";
> +	phandle = <0x1000006b>;
> +	linux,phandle = <0x1000006b>;
> +	led-mode = "lightpath";
> +
> +	U78C9.001.RST0027-P1-C1 {

DT node names should be in lowercase form.
Is U78C9.001.RST0027-P1-C1 a location code?

> +		led-types = "identify", "fault";
> +		led-loc = "descendent";
> +		phandle = <0x1000006f>;
> +		linux,phandle = <0x1000006f>;
> +	};
> +	...
> +	...
> +};
> +
> +
> +'compatible' property describes LEDs compatibility.

compatible doesn't need to be mentioned here.

> +'led-mode' property describes service indicator mode (lightpath/guidinglight).

You don't parse this in the driver? What is its purpose?

> +
> +Each node under 'led' node describes location code of FRU/Enclosure.
> +
> +The properties under each node:
> +
> +  led-types : Supported indicators (attention/identify/fault).
> +
> +  led-loc   : enclosure/descendent(FRU) location code.
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 25b320d..2ea0849 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -508,6 +508,17 @@ 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
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index cbba921..604ffc9 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -58,6 +58,7 @@ obj-$(CONFIG_LEDS_BLINKM)		+= leds-blinkm.o
>   obj-$(CONFIG_LEDS_SYSCON)		+= leds-syscon.o
>   obj-$(CONFIG_LEDS_VERSATILE)		+= leds-versatile.o
>   obj-$(CONFIG_LEDS_MENF21BMC)		+= leds-menf21bmc.o
> +obj-$(CONFIG_LEDS_POWERNV)		+= leds-powernv.o
>
>   # LED SPI Drivers
>   obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
> diff --git a/drivers/leds/leds-powernv.c b/drivers/leds/leds-powernv.c
> new file mode 100644
> index 0000000..e3c033d
> --- /dev/null
> +++ b/drivers/leds/leds-powernv.c
> @@ -0,0 +1,455 @@
> +/*
> + * PowerNV LED Driver
> + *
> + * Copyright IBM Corp. 2015
> + *
> + * Author: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
> + * Author: Anshuman Khandual <khandual@linux.vnet.ibm.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#define PREFIX		"POWERNV_LED"
> +
> +#include <linux/leds.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#include <asm/opal.h>
> +
> +#define POWERNV_LED_ATTN	":ATTENTION"
> +#define POWERNV_LED_IDENT	":IDENT"
> +#define POWERNV_LED_FAULT	":FAULT"
> +
> +/*
> + * By default unload path resets all the LEDs. But on PowerNV platform
> + * we want to retain LED state across reboot as these are controlled by
> + * firmware. Also service processor can modify the LEDs independent of
> + * OS. Hence avoid resetting LEDs in unload path.
> + */
> +static bool led_disabled;

I think that we have to make it configurable from the Device Tree level.
There could be a 'retain-state-removed' property introduced.

There is also another implication - you define LED_CORE_SUSPENDRESUME
flag. With current approach it wouldn't turn the led off on suspend.
Please either drop the flag or assure correct behaviour on suspend.
You can also make this configurable like retain-state-suspended
property in Documentation/devicetree/bindings/leds/leds-gpio.txt.

> +
> +/* Converts LED event type into it's description. */
> +static const char *led_type_map[OPAL_SLOT_LED_TYPE_MAX] = {
> +	"Attention", "Ident", "Fault"
> +};
> +
> +/*
> + * LED set routines have been implemented as work queue tasks scheduled
> + * on the global work queue. Individual task calls OPAL interface to set
> + * the LED state which might sleep for some time.
> + */
> +struct powernv_led_data {
> +	struct led_classdev	cdev;
> +
> +	u64			led_type;  /* Attention or Ident or Fault */
> +	enum led_brightness	value;     /* Brightness value */
> +
> +	struct mutex		lock;
> +	struct work_struct	work_led; /* LED update workqueue */
> +
> +	struct list_head	link;
> +};
> +static LIST_HEAD(powernv_led_list);
> +
> +
> +/* Get LED location code based on LED name */
> +static int powernv_get_loc_code(u64 led_type, char *loc_code)
> +{
> +	switch (led_type) {
> +	case OPAL_SLOT_LED_TYPE_ATTN:
> +		loc_code[strlen(loc_code) - strlen(POWERNV_LED_ATTN)] = '\0';
> +		break;
> +	case OPAL_SLOT_LED_TYPE_ID:
> +		loc_code[strlen(loc_code) - strlen(POWERNV_LED_IDENT)] = '\0';
> +		break;
> +	case OPAL_SLOT_LED_TYPE_FAULT:
> +		loc_code[strlen(loc_code) - strlen(POWERNV_LED_FAULT)] = '\0';
> +		break;
> +	default:	/* Unsupported LED type */
> +		return -1;
> +	}
> +	return 0;
> +}
> +
> +/*
> + * This commits the state change of the requested LED through an OPAL call.
> + * This function is called from work queue task context when ever it gets
> + * scheduled. This function can sleep at opal_async_wait_response call.
> + */
> +static void powernv_led_set(struct led_classdev *led_cdev,
> +			    enum led_brightness value, u64 led_type)
> +{
> +	char *loc_code;
> +	int rc, token;
> +	u64 led_mask, max_led_type, led_value = 0;
> +	struct opal_msg msg;
> +
> +	/* Location code of the LED */
> +	loc_code = kasprintf(GFP_KERNEL, "%s", led_cdev->name);
> +	if (!loc_code) {
> +		dev_err(led_cdev->dev,
> +			"%s: Memory allocation failed\n", __func__);
> +		return;
> +	}
> +
> +	if (powernv_get_loc_code(led_type, loc_code) != 0)
> +		goto out_loc;
> +
> +	/* Prepare for the OPAL call */
> +	max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
> +	led_mask = OPAL_SLOT_LED_STATE_ON << led_type;
> +	if (value)
> +		led_value = OPAL_SLOT_LED_STATE_ON << led_type;

		led_value = led_mask;

> +
> +	/* OPAL async call */
> +	token = opal_async_get_token_interruptible();
> +	if (token < 0) {
> +		if (token != -ERESTARTSYS)
> +			dev_err(led_cdev->dev,
> +				"%s: Couldn't get OPAL async token\n",
> +				__func__);
> +		goto out_loc;
> +	}
> +
> +	rc = opal_leds_set_ind(token, loc_code,
> +			       led_mask, led_value, &max_led_type);
> +	if (rc != OPAL_ASYNC_COMPLETION) {
> +		dev_err(led_cdev->dev,
> +			"%s: OPAL set LED call failed for %s [rc=%d]\n",
> +			__func__, loc_code, rc);
> +		goto out_token;
> +	}
> +
> +	rc = opal_async_wait_response(token, &msg);
> +	if (rc) {
> +		dev_err(led_cdev->dev,
> +			"%s: Failed to wait for the async response [rc=%d]\n",
> +			__func__, rc);
> +		goto out_token;
> +	}
> +
> +	rc = be64_to_cpu(msg.params[1]);
> +	if (rc != OPAL_SUCCESS)
> +		dev_err(led_cdev->dev,
> +			"%s : OAPL async call returned failed [rc=%d]\n",
> +			__func__, rc);
> +
> +out_token:
> +	opal_async_release_token(token);
> +
> +out_loc:
> +	kfree(loc_code);
> +}
> +
> +/*
> + * This function fetches the LED state for a given LED type for
> + * mentioned LED classdev structure.
> + */
> +static enum led_brightness powernv_led_get(struct led_classdev *led_cdev,
> +					   u64 led_type)
> +{
> +	char *loc_code;
> +	int rc;
> +	u64 led_mask, led_value, max_led_type;
> +
> +	/* LED location code */
> +	loc_code = kasprintf(GFP_KERNEL, "%s", led_cdev->name);
> +	if (!loc_code) {
> +		dev_err(led_cdev->dev,
> +			"%s: Memory allocation failed\n", __func__);
> +		return -ENOMEM;
> +	}
> +
> +	if (powernv_get_loc_code(led_type, loc_code) != 0)
> +		goto led_fail;
> +
> +	/* Fetch all LED status */
> +	led_mask = cpu_to_be64(0);
> +	led_value = cpu_to_be64(0);
> +	max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
> +
> +	rc = opal_leds_get_ind(loc_code, &led_mask, &led_value, &max_led_type);
> +	if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
> +		dev_err(led_cdev->dev,
> +			"%s: OPAL get led call failed [rc=%d]\n",
> +			__func__, rc);
> +		goto led_fail;
> +	}
> +
> +	led_mask = be64_to_cpu(led_mask);
> +	led_value = be64_to_cpu(led_value);
> +
> +	/* LED status available */
> +	if (!((led_mask >> led_type) & OPAL_SLOT_LED_STATE_ON)) {
> +		dev_err(led_cdev->dev,
> +			"%s: %s LED status not available for %s\n",
> +			__func__, led_type_map[led_type], loc_code);
> +		goto led_fail;
> +	}
> +
> +	/* LED status value */
> +	if ((led_value >> led_type) & OPAL_SLOT_LED_STATE_ON) {
> +		kfree(loc_code);
> +		return LED_FULL;
> +	}
> +
> +led_fail:
> +	kfree(loc_code);
> +	return LED_OFF;
> +}
> +
> +/*
> + * This the function which will be executed by any LED work task on the
> + * global work queue.
> + */
> +static void powernv_deferred_led_set(struct work_struct *work)
> +{
> +	struct powernv_led_data *powernv_led =
> +		container_of(work, struct powernv_led_data, work_led);
> +
> +	mutex_lock(&powernv_led->lock);
> +	powernv_led_set(&powernv_led->cdev,
> +			powernv_led->value, powernv_led->led_type);
> +	mutex_unlock(&powernv_led->lock);
> +}
> +
> +/* Schedule work to update LED state */
> +static void powernv_led_set_queue(struct led_classdev *led_cdev,
> +				  enum led_brightness value, u64 led_type)

It doesn't set any queue. It should be powernv_brightness_set.

> +{
> +	struct powernv_led_data *powernv_led =
> +		container_of(led_cdev, struct powernv_led_data, cdev);
> +
> +	/* Do not modify LED in unload path */
> +	if (led_disabled)
> +		return;
> +
> +	/* Prepare the request */
> +	powernv_led->value = value;
> +	powernv_led->led_type = led_type;
> +
> +	/* Schedule the new task */
> +	schedule_work(&powernv_led->work_led);
> +}
> +
> +
> +/* LED classdev 'brightness_set' function for attention LED. */
> +static void powernv_led_set_attn(struct led_classdev *led_cdev,
> +				  enum led_brightness value)
> +{
> +	return powernv_led_set_queue(led_cdev, value, OPAL_SLOT_LED_TYPE_ATTN);
> +}
> +
> +/* LED classdev 'brightness_get' function for attention LED.  */
> +static enum led_brightness powernv_led_get_attn(struct led_classdev *led_cdev)
> +{
> +	return powernv_led_get(led_cdev, OPAL_SLOT_LED_TYPE_ATTN);
> +}
> +
> +/* LED classdev 'brightness_set' function for ident LED types. */
> +static void powernv_led_set_ident(struct led_classdev *led_cdev,
> +				  enum led_brightness value)
> +{
> +	return powernv_led_set_queue(led_cdev, value, OPAL_SLOT_LED_TYPE_ID);
> +}
> +
> +/* LED classdev 'brightness_get' function for ident LED types. */
> +static enum led_brightness powernv_led_get_ident(struct led_classdev *led_cdev)
> +{
> +	return powernv_led_get(led_cdev, OPAL_SLOT_LED_TYPE_ID);
> +}
> +
> +/* LED classdev 'brightness_set' function for fault LED types. */
> +static void powernv_led_set_fault(struct led_classdev *led_cdev,
> +				  enum led_brightness value)
> +{
> +	return powernv_led_set_queue(led_cdev, value, OPAL_SLOT_LED_TYPE_FAULT);
> +}
> +
> +/* LED classdev 'brightness_get' function for fault LED types. */
> +static enum led_brightness powernv_led_get_fault(struct led_classdev *led_cdev)
> +{
> +	return powernv_led_get(led_cdev, OPAL_SLOT_LED_TYPE_FAULT);
> +}
> +
> +
> +/*
> + * This function verifies whether the child LED device node supports certain
> + * type of LED or not. This will be used to register LED classdev structures
> + * for that particual type of LED for a given device tree node.
> + */
> +static bool has_led_type(struct device_node *node, const char *led_type)
> +{
> +	bool result = false;
> +
> +	if (of_property_match_string(node, "led-types", led_type) >= 0)
> +		result = true;
> +
> +	return result;
> +}
> +
> +/*
> + * This function registers classdev structure for any given type of LED on
> + * a given child LED device node.
> + */
> +static int power_led_classdev(struct platform_device *pdev,
> +			      struct device_node *node, u64 led_type)
> +{
> +	int rc;
> +	struct powernv_led_data *powernv_led;
> +
> +	powernv_led = kzalloc(sizeof(struct powernv_led_data), GFP_KERNEL);
> +	if (!powernv_led) {
> +		dev_err(&pdev->dev,
> +			"%s: Memory allocation failed\n", __func__);
> +		return -ENOMEM;
> +	}
> +
> +	/* Create the name for classdev */
> +	switch (led_type) {
> +	case OPAL_SLOT_LED_TYPE_ATTN:
> +		powernv_led->cdev.name = kasprintf(GFP_KERNEL,
> +						   "%s%s", node->name,
> +						   POWERNV_LED_ATTN);

LED name should be taken from of_node name or label property directly.
Please refer to the other LED class drivers.

> +		powernv_led->cdev.brightness_set = powernv_led_set_attn;
> +		powernv_led->cdev.brightness_get = powernv_led_get_attn;
> +		break;
> +	case OPAL_SLOT_LED_TYPE_ID:
> +		powernv_led->cdev.name = kasprintf(GFP_KERNEL,
> +						   "%s%s", node->name,
> +						   POWERNV_LED_IDENT);
> +		powernv_led->cdev.brightness_set = powernv_led_set_ident;
> +		powernv_led->cdev.brightness_get = powernv_led_get_ident;
> +		break;
> +	case OPAL_SLOT_LED_TYPE_FAULT:
> +		powernv_led->cdev.name = kasprintf(GFP_KERNEL,
> +						   "%s%s", node->name,
> +						   POWERNV_LED_FAULT);
> +		powernv_led->cdev.brightness_set = powernv_led_set_fault;
> +		powernv_led->cdev.brightness_get = powernv_led_get_fault;
> +		break;
> +	default: /* Unsupported LED type */
> +		kfree(powernv_led);
> +		return -EINVAL;
> +	}
> +
> +	if (!powernv_led->cdev.name) {
> +		dev_err(&pdev->dev,
> +			"%s: Memory allocation failed for classdev name\n",
> +			__func__);
> +		kfree(powernv_led);
> +		return -ENOMEM;
> +	}
> +
> +	powernv_led->cdev.brightness = LED_OFF;
> +	powernv_led->cdev.max_brightness = LED_FULL;
> +	powernv_led->cdev.flags = LED_CORE_SUSPENDRESUME;
> +
> +	mutex_init(&powernv_led->lock);
> +	INIT_WORK(&powernv_led->work_led, powernv_deferred_led_set);
> +
> +	/* Register the classdev */
> +	rc = led_classdev_register(&pdev->dev, &powernv_led->cdev);
> +	if (rc) {
> +		dev_err(&pdev->dev, "%s: Classdev registration failed for %s\n",
> +			__func__, powernv_led->cdev.name);
> +		kfree(powernv_led->cdev.name);
> +		kfree(powernv_led);
> +	} else {
> +		list_add_tail(&powernv_led->link, &powernv_led_list);

You don't need a list. powernv_led can be allocated with devm_kzalloc
and it will be released on remove automatically.

> +		dev_dbg(&pdev->dev,
> +			"Classdev registration successful for %s\n",
> +			powernv_led->cdev.name);
> +	}
> +	return rc;
> +}
> +
> +/* Platform driver probe */
> +static int powernv_led_probe(struct platform_device *pdev)
> +{
> +	int rc = 0;
> +	struct device_node *led_node, *np;
> +
> +	led_node = of_find_node_by_path("/ibm,opal/led");
> +	if (!led_node) {
> +		dev_err(&pdev->dev,
> +			"%s: LED parent device node not found\n", __func__);
> +		return -EINVAL;
> +	}
> +
> +	for_each_child_of_node(led_node, np) {
> +		if (has_led_type(np, LED_TYPE_ATTENTION))
> +			rc = power_led_classdev(pdev, np,
> +						OPAL_SLOT_LED_TYPE_ATTN);
> +
> +		if (has_led_type(np, LED_TYPE_IDENTIFY))
> +			rc = power_led_classdev(pdev, np,
> +						OPAL_SLOT_LED_TYPE_ID);
> +
> +		if (has_led_type(np, LED_TYPE_FAULT))
> +			rc = power_led_classdev(pdev, np,
> +						OPAL_SLOT_LED_TYPE_FAULT);
> +	}
> +	return rc;
> +}
> +
> +/* Platform driver remove */
> +static int powernv_led_remove(struct platform_device *pdev)
> +{
> +	struct powernv_led_data *powernv_led;
> +
> +	/* Disable LED operation */
> +	led_disabled = true;
> +
> +	dev_dbg(&pdev->dev,
> +		"%s: Unregister all classdev structures\n", __func__);
> +	list_for_each_entry(powernv_led, &powernv_led_list, link)
> +		led_classdev_unregister(&powernv_led->cdev);
> +
> +	dev_dbg(&pdev->dev,
> +		"%s: Wait for all work tasks to finish\n", __func__);
> +	list_for_each_entry(powernv_led, &powernv_led_list, link)
> +		flush_work(&powernv_led->work_led);
> +
> +	while (!list_empty(&powernv_led_list)) {
> +		powernv_led = list_first_entry(&powernv_led_list,
> +					       struct powernv_led_data, link);
> +		list_del(&powernv_led->link);
> +		kfree(powernv_led);
> +	}
> +
> +	dev_info(&pdev->dev, "PowerNV led module unregistered\n");
> +	return 0;
> +}
> +
> +/* Platform driver property match */
> +static const struct of_device_id powernv_led_match[] = {
> +	{
> +		.compatible	= "ibm,opal-v3-led",
> +	},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, powernv_led_match);
> +
> +static struct platform_driver powernv_led_driver = {
> +	.probe	= powernv_led_probe,
> +	.remove = powernv_led_remove,
> +	.driver = {
> +		.name = "powernv-led-driver",
> +		.owner = THIS_MODULE,
> +		.of_match_table = powernv_led_match,
> +	},
> +};
> +
> +module_platform_driver(powernv_led_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("PowerNV LED driver");
> +MODULE_AUTHOR("Vasant Hegde <hegdevasant@linux.vnet.ibm.com>");
>
>


-- 
Best Regards,
Jacek Anaszewski

Re: [PATCH v3 3/3] leds/powernv: Add driver for PowerNV platform

[Vasant Hegde]

On 04/20/2015 08:57 PM, Jacek Anaszewski wrote:
> Hi Vasant,
> 

Jacek,

Thanks for the review.

> Thanks for the update.
> 
> On 04/20/2015 10:01 AM, Vasant Hegde wrote:
>> 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 registers classdev structures for all individual LEDs detected on the
> 
> s/registers/register

Fixed.

> 
>> 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. Hence our LEDs have names in this format.
>>
>>          <location_code>:<ATTENTION|IDENT|FAULT>
> 
> I think that powernv prefix should be also present in the beginning.
> What would be the format of <location_code> ? Does it identify a LED
> uniquely.

Location code is unique and its guaranteed that we don't clash here. Also this
is platform specific LEDs and I don't see any value by prefixing "powernv".
Hence I think its fine with current format.

Sample location code : U78C9.001.RST0027-P1-C1
  Here "U78C9.001.RST0027" represents the system model
             P1 - Planar 1
             C1 - Card 1

.../...

>> +led {
>> +    compatible = "ibm,opal-v3-led";
>> +    phandle = <0x1000006b>;
>> +    linux,phandle = <0x1000006b>;
>> +    led-mode = "lightpath";
>> +
>> +    U78C9.001.RST0027-P1-C1 {
> 
> DT node names should be in lowercase form.
> Is U78C9.001.RST0027-P1-C1 a location code?

Yes ... Node presents the location code.. Platform provides these location code
in upper case. Hence our OPAL firmware exposes them in upper case.

> 
>> +        led-types = "identify", "fault";
>> +        led-loc = "descendent";
>> +        phandle = <0x1000006f>;
>> +        linux,phandle = <0x1000006f>;
>> +    };
>> +    ...
>> +    ...
>> +};
>> +
>> +
>> +'compatible' property describes LEDs compatibility.
> 
> compatible doesn't need to be mentioned here.

Removed.

> 
>> +'led-mode' property describes service indicator mode (lightpath/guidinglight).
> 
> You don't parse this in the driver? What is its purpose?

As mentioned in other thread, currently our driver doesn't parse this. (As mode
is provided by platform and its static).

Do you want me to elaborate this property here?

.../...

>> +
>> +/*
>> + * By default unload path resets all the LEDs. But on PowerNV platform
>> + * we want to retain LED state across reboot as these are controlled by
>> + * firmware. Also service processor can modify the LEDs independent of
>> + * OS. Hence avoid resetting LEDs in unload path.
>> + */
>> +static bool led_disabled;
> 
> I think that we have to make it configurable from the Device Tree level.
> There could be a 'retain-state-removed' property introduced.

Hmmm.. In my case, LED behavior is not going to change. Hence I don't think we
need this property.

> 
> There is also another implication - you define LED_CORE_SUSPENDRESUME
> flag. With current approach it wouldn't turn the led off on suspend.
> Please either drop the flag or assure correct behaviour on suspend.

I will drop this.

> You can also make this configurable like retain-state-suspended
> property in Documentation/devicetree/bindings/leds/leds-gpio.txt.
> 

.../...

>> +
>> +    if (powernv_get_loc_code(led_type, loc_code) != 0)
>> +        goto out_loc;
>> +
>> +    /* Prepare for the OPAL call */
>> +    max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
>> +    led_mask = OPAL_SLOT_LED_STATE_ON << led_type;
>> +    if (value)
>> +        led_value = OPAL_SLOT_LED_STATE_ON << led_type;
> 
>         led_value = led_mask;

Fixed.

.../...

>> +
>> +/* Schedule work to update LED state */
>> +static void powernv_led_set_queue(struct led_classdev *led_cdev,
>> +                  enum led_brightness value, u64 led_type)
> 
> It doesn't set any queue. It should be powernv_brightness_set.

Make sense. Fixed.

.../...

>> +    /* Create the name for classdev */
>> +    switch (led_type) {
>> +    case OPAL_SLOT_LED_TYPE_ATTN:
>> +        powernv_led->cdev.name = kasprintf(GFP_KERNEL,
>> +                           "%s%s", node->name,
>> +                           POWERNV_LED_ATTN);
> 
> LED name should be taken from of_node name or label property directly.
> Please refer to the other LED class drivers.

Hmmm.. Our  current FW provides led-types property which tells available type
for given location code..
like
  led-types = "identify" "fault"..

Can I use this ? So the names will be
   <location_code>:<identify|fault|attention>

And if this approach fine,  I can fix (assuming maintainer agrees :-) ) firmware
side to change identify -> ident.


.../...


>> +        list_add_tail(&powernv_led->link, &powernv_led_list);
> 
> You don't need a list. powernv_led can be allocated with devm_kzalloc
> and it will be released on remove automatically.


Sure. .will look into it.

-Vasant