Subject: Re: [PATCH v8 3/3] leds/powernv: Add driver for PowerNV platform

From: Jacek Anaszewski <[email-masked]>
Date: Mon, 27 Jul 2015 11:50:21 +0200

Hi Vasant,

On 27.07.2015 05:41, Vasant Hegde wrote:
> On 07/27/2015 03:11 AM, Jacek Anaszewski wrote:
>> Hi Vasant,
>>
>
> Hi Jacek,
>
>> Two trivial details left. Please find them below.
>
> Thanks for the review/Ack. I'll fix below issues and resend patchset.
>
> I will ask Benh/Michael to take this patchset. But this patchset is depending
> on your core changes. Can you confirm that you are pushing that patchset in next
> merge window?

Without my core changes your driver won't work with led triggers, but
AFAIR this use case is not relevant for your LEDs? Eventually, we could
produce a patch set adding support for LED triggers if it will be clear
that LED core changes will not be merged in the upcoming merge window.

> -Vasant
>
>
>>
>> Since for two next weeks I will be unable even to compile-test
>> this patch set I propose to merge it via powerpc tree.
>>
>> Having both mentioned issues addressed, for this patch:
>>
>> Acked-by: Jacek Anaszewski <[email-masked]>
>>
>> On 25.07.2015 07:21, 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 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.
>>>
>>> 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.
>>
>> This is no longer true.
>>
>>> 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 <[email-masked]>
>>> Signed-off-by: Anshuman Khandual <[email-masked]>
>>> Acked-by: Stewart Smith <[email-masked]>
>>> Tested-by: Stewart Smith <[email-masked]>
>>> ---
>>>    .../devicetree/bindings/leds/leds-powernv.txt      |  26 ++
>>>    drivers/leds/Kconfig                               |  11 +
>>>    drivers/leds/Makefile                              |   1 +
>>>    drivers/leds/leds-powernv.c                        | 350 +++++++++++++++++++++
>>>    4 files changed, 388 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..6665569
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/leds/leds-powernv.txt
>>> @@ -0,0 +1,26 @@
>>> +Device Tree binding for LEDs on IBM Power Systems
>>> +-------------------------------------------------
>>> +
>>> +Required properties:
>>> +- compatible : Should be "ibm,opal-v3-led".
>>> +- led-mode   : Should be "lightpath" or "guidinglight".
>>> +
>>> +Each location code of FRU/Enclosure must be expressed in the
>>> +form of a sub-node.
>>> +
>>> +Required properties for the sub nodes:
>>> +- led-types : Supported LED types (attention/identify/fault) provided
>>> +              in the form of string array.
>>> +
>>> +Example:
>>> +
>>> +leds {
>>> +    compatible = "ibm,opal-v3-led";
>>> +    led-mode = "lightpath";
>>> +
>>> +    U78C9.001.RST0027-P1-C1 {
>>> +        led-types = "identify", "fault";
>>> +    };
>>> +    ...
>>> +    ...
>>> +};
>>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>>> index 9ad35f7..f218cc3a 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
>>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>>> index 8d6a24a..6a943d1 100644
>>> --- a/drivers/leds/Makefile
>>> +++ b/drivers/leds/Makefile
>>> @@ -65,6 +65,7 @@ obj-$(CONFIG_LEDS_VERSATILE)        += leds-versatile.o
>>>    obj-$(CONFIG_LEDS_MENF21BMC)        += leds-menf21bmc.o
>>>    obj-$(CONFIG_LEDS_PM8941_WLED)        += leds-pm8941-wled.o
>>>    obj-$(CONFIG_LEDS_KTD2692)        += leds-ktd2692.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..9799de5
>>> --- /dev/null
>>> +++ b/drivers/leds/leds-powernv.c
>>> @@ -0,0 +1,350 @@
>>> +/*
>>> + * PowerNV LED Driver
>>> + *
>>> + * Copyright IBM Corp. 2015
>>> + *
>>> + * Author: Vasant Hegde <[email-masked]>
>>> + * Author: Anshuman Khandual <[email-masked]>
>>> + *
>>> + * 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.
>>> + */
>>> +
>>> +#include <linux/leds.h>
>>> +#include <linux/module.h>
>>> +#include <linux/of.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/types.h>
>>> +
>>> +#include <asm/opal.h>
>>> +
>>> +/* Map LED type to description. */
>>> +struct led_type_map {
>>> +    const int    type;
>>> +    const char    *desc;
>>> +};
>>> +static const struct led_type_map led_type_map[] = {
>>> +    {OPAL_SLOT_LED_TYPE_ID,        POWERNV_LED_TYPE_IDENTIFY},
>>> +    {OPAL_SLOT_LED_TYPE_FAULT,    POWERNV_LED_TYPE_FAULT},
>>> +    {OPAL_SLOT_LED_TYPE_ATTN,    POWERNV_LED_TYPE_ATTENTION},
>>> +    {-1,                NULL},
>>> +};
>>> +
>>> +struct powernv_led_common {
>>> +    /*
>>> +     * 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.
>>> +     */
>>> +    bool        led_disabled;
>>> +
>>> +    /* Max supported LED type */
>>> +    __be64        max_led_type;
>>> +
>>> +    /* glabal lock */
>>> +    struct mutex    lock;
>>> +};
>>> +
>>> +/* PowerNV LED data */
>>> +struct powernv_led_data {
>>> +    struct led_classdev    cdev;
>>> +    char            *loc_code;    /* LED location code */
>>> +    int            led_type;    /* OPAL_SLOT_LED_TYPE_* */
>>> +
>>> +    struct powernv_led_common *common;
>>> +};
>>> +
>>> +
>>> +/* Returns OPAL_SLOT_LED_TYPE_* for given led type string */
>>> +static int powernv_get_led_type(const char *led_type_desc)
>>> +{
>>> +    int i;
>>> +
>>> +    for (i = 0; i < ARRAY_SIZE(led_type_map); i++)
>>> +        if (!strcmp(led_type_map[i].desc, led_type_desc))
>>> +            return led_type_map[i].type;
>>> +
>>> +    return -1;
>>> +}
>>> +
>>> +/*
>>> + * 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 powernv_led_data *powernv_led,
>>> +                enum led_brightness value)
>>> +{
>>> +    int rc, token;
>>> +    u64 led_mask, led_value = 0;
>>> +    __be64 max_type;
>>> +    struct opal_msg msg;
>>> +    struct device *dev = powernv_led->cdev.dev;
>>> +    struct powernv_led_common *powernv_led_common = powernv_led->common;
>>> +
>>> +    /* Prepare for the OPAL call */
>>> +    max_type = powernv_led_common->max_led_type;
>>> +    led_mask = OPAL_SLOT_LED_STATE_ON << powernv_led->led_type;
>>> +    if (value)
>>> +        led_value = led_mask;
>>> +
>>> +    /* OPAL async call */
>>> +    token = opal_async_get_token_interruptible();
>>> +    if (token < 0) {
>>> +        if (token != -ERESTARTSYS)
>>> +            dev_err(dev, "%s: Couldn't get OPAL async token\n",
>>> +                __func__);
>>> +        return;
>>> +    }
>>> +
>>> +    rc = opal_leds_set_ind(token, powernv_led->loc_code,
>>> +                   led_mask, led_value, &max_type);
>>> +    if (rc != OPAL_ASYNC_COMPLETION) {
>>> +        dev_err(dev, "%s: OPAL set LED call failed for %s [rc=%d]\n",
>>> +            __func__, powernv_led->loc_code, rc);
>>> +        goto out_token;
>>> +    }
>>> +
>>> +    rc = opal_async_wait_response(token, &msg);
>>> +    if (rc) {
>>> +        dev_err(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(dev, "%s : OAPL async call returned failed [rc=%d]\n",
>>> +            __func__, rc);
>>> +
>>> +out_token:
>>> +    opal_async_release_token(token);
>>> +}
>>> +
>>> +/*
>>> + * This function fetches the LED state for a given LED type for
>>> + * mentioned LED classdev structure.
>>> + */
>>> +static enum led_brightness
>>> +powernv_led_get(struct powernv_led_data *powernv_led)
>>
>> This fits on a single line.
>>
>>> +{
>>> +    int rc;
>>> +    __be64 mask, value, max_type;
>>> +    u64 led_mask, led_value;
>>> +    struct device *dev = powernv_led->cdev.dev;
>>> +    struct powernv_led_common *powernv_led_common = powernv_led->common;
>>> +
>>> +    /* Fetch all LED status */
>>> +    mask = cpu_to_be64(0);
>>> +    value = cpu_to_be64(0);
>>> +    max_type = powernv_led_common->max_led_type;
>>> +
>>> +    rc = opal_leds_get_ind(powernv_led->loc_code,
>>> +                   &mask, &value, &max_type);
>>> +    if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
>>> +        dev_err(dev, "%s: OPAL get led call failed [rc=%d]\n",
>>> +            __func__, rc);
>>> +        return LED_OFF;
>>> +    }
>>> +
>>> +    led_mask = be64_to_cpu(mask);
>>> +    led_value = be64_to_cpu(value);
>>> +
>>> +    /* LED status available */
>>> +    if (!((led_mask >> powernv_led->led_type) & OPAL_SLOT_LED_STATE_ON)) {
>>> +        dev_err(dev, "%s: LED status not available for %s\n",
>>> +            __func__, powernv_led->cdev.name);
>>> +        return LED_OFF;
>>> +    }
>>> +
>>> +    /* LED status value */
>>> +    if ((led_value >> powernv_led->led_type) & OPAL_SLOT_LED_STATE_ON)
>>> +        return LED_FULL;
>>> +
>>> +    return LED_OFF;
>>> +}
>>> +
>>> +/*
>>> + * LED classdev 'brightness_get' function. This schedules work
>>> + * to update LED state.
>>> + */
>>> +static void powernv_brightness_set(struct led_classdev *led_cdev,
>>> +                   enum led_brightness value)
>>> +{
>>> +    struct powernv_led_data *powernv_led =
>>> +        container_of(led_cdev, struct powernv_led_data, cdev);
>>> +    struct powernv_led_common *powernv_led_common = powernv_led->common;
>>> +
>>> +    /* Do not modify LED in unload path */
>>> +    if (powernv_led_common->led_disabled)
>>> +        return;
>>> +
>>> +    mutex_lock(&powernv_led_common->lock);
>>> +    powernv_led_set(powernv_led, value);
>>> +    mutex_unlock(&powernv_led_common->lock);
>>> +}
>>> +
>>> +/* LED classdev 'brightness_get' function */
>>> +static enum led_brightness
>>> +powernv_brightness_get(struct led_classdev *led_cdev)
>>> +{
>>> +    struct powernv_led_data *powernv_led =
>>> +        container_of(led_cdev, struct powernv_led_data, cdev);
>>> +
>>> +    return powernv_led_get(powernv_led);
>>> +}
>>> +
>>
>> Unnecessary empty line.
>>
>>> +
>>> +/*
>>> + * This function registers classdev structure for any given type of LED on
>>> + * a given child LED device node.
>>> + */
>>> +static int powernv_led_create(struct device *dev,
>>> +                  struct powernv_led_data *powernv_led,
>>> +                  const char *led_type_desc)
>>> +{
>>> +    int rc;
>>> +
>>> +    /* Make sure LED type is supported */
>>> +    powernv_led->led_type = powernv_get_led_type(led_type_desc);
>>> +    if (powernv_led->led_type == -1) {
>>> +        dev_warn(dev, "%s: No support for led type : %s\n",
>>> +             __func__, led_type_desc);
>>> +        return -EINVAL;
>>> +    }
>>> +
>>> +    /* Create the name for classdev */
>>> +    powernv_led->cdev.name = devm_kasprintf(dev, GFP_KERNEL, "%s:%s",
>>> +                        powernv_led->loc_code,
>>> +                        led_type_desc);
>>> +    if (!powernv_led->cdev.name) {
>>> +        dev_err(dev,
>>> +            "%s: Memory allocation failed for classdev name\n",
>>> +            __func__);
>>> +        return -ENOMEM;
>>> +    }
>>> +
>>> +    powernv_led->cdev.brightness_set = powernv_brightness_set;
>>> +    powernv_led->cdev.brightness_get = powernv_brightness_get;
>>> +    powernv_led->cdev.brightness = LED_OFF;
>>> +    powernv_led->cdev.max_brightness = LED_FULL;
>>> +
>>> +    /* Register the classdev */
>>> +    rc = devm_led_classdev_register(dev, &powernv_led->cdev);
>>> +    if (rc) {
>>> +        dev_err(dev, "%s: Classdev registration failed for %s\n",
>>> +            __func__, powernv_led->cdev.name);
>>> +    }
>>> +
>>> +    return rc;
>>> +}
>>> +
>>> +/* Go through LED device tree node and register LED classdev structure */
>>> +static int powernv_led_classdev(struct platform_device *pdev,
>>> +                struct device_node *led_node,
>>> +                struct powernv_led_common *powernv_led_common)
>>> +{
>>> +    const char *cur = NULL;
>>> +    int rc = -1;
>>> +    struct property *p;
>>> +    struct device_node *np;
>>> +    struct powernv_led_data *powernv_led;
>>> +    struct device *dev = &pdev->dev;
>>> +
>>> +    for_each_child_of_node(led_node, np) {
>>> +        p = of_find_property(np, "led-types", NULL);
>>> +        if (!p)
>>> +            continue;
>>> +
>>> +        while ((cur = of_prop_next_string(p, cur)) != NULL) {
>>> +            powernv_led = devm_kzalloc(dev, sizeof(*powernv_led),
>>> +                           GFP_KERNEL);
>>> +            if (!powernv_led)
>>> +                return -ENOMEM;
>>> +
>>> +            powernv_led->common = powernv_led_common;
>>> +            powernv_led->loc_code = (char *)np->name;
>>> +
>>> +            rc = powernv_led_create(dev, powernv_led, cur);
>>> +            if (rc)
>>> +                return rc;
>>> +        } /* while end */
>>> +    }
>>> +
>>> +    return rc;
>>> +}
>>> +
>>> +/* Platform driver probe */
>>> +static int powernv_led_probe(struct platform_device *pdev)
>>> +{
>>> +    struct device_node *led_node;
>>> +    struct powernv_led_common *powernv_led_common;
>>> +    struct device *dev = &pdev->dev;
>>> +
>>> +    led_node = of_find_node_by_path("/ibm,opal/leds");
>>> +    if (!led_node) {
>>> +        dev_err(dev, "%s: LED parent device node not found\n",
>>> +            __func__);
>>> +        return -EINVAL;
>>> +    }
>>> +
>>> +    powernv_led_common = devm_kzalloc(dev, sizeof(*powernv_led_common),
>>> +                      GFP_KERNEL);
>>> +    if (!powernv_led_common)
>>> +        return -ENOMEM;
>>> +
>>> +    mutex_init(&powernv_led_common->lock);
>>> +    powernv_led_common->max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
>>> +    powernv_led_common->led_disabled = false;
>>> +
>>> +    platform_set_drvdata(pdev, powernv_led_common);
>>> +
>>> +    return powernv_led_classdev(pdev, led_node, powernv_led_common);
>>> +}
>>> +
>>> +/* Platform driver remove */
>>> +static int powernv_led_remove(struct platform_device *pdev)
>>> +{
>>> +    struct powernv_led_common *powernv_led_common;
>>> +
>>> +    /* Disable LED operation */
>>> +    powernv_led_common = platform_get_drvdata(pdev);
>>> +    powernv_led_common->led_disabled = true;
>>> +
>>> +    /* Destroy lock */
>>> +    mutex_destroy(&powernv_led_common->lock);
>>> +
>>> +    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 v2");
>>> +MODULE_DESCRIPTION("PowerNV LED driver");
>>> +MODULE_AUTHOR("Vasant Hegde <[email-masked]>");
>>>
>>
>
>

-- 
Best Regards,
Jacek Anaszewski