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

From: Vasant Hegde <[email-masked]>
Date: Mon, 27 Jul 2015 09:11:07 +0530

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?

-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]>");
>>
>