Subject: Re: [PATCH v6 3/3] leds/powernv: Add driver for PowerNV platform

From: Vasant Hegde <[email-masked]>
Date: Fri, 17 Jul 2015 21:50:20 +0530

On 07/17/2015 08:55 PM, Jacek Anaszewski wrote:
> Hi Vasant,

Hi Jacek,

.../...

>> 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
> 
> Please don't exceed 75 character line length limit.

Ok. I will fix it.. But I thought 80 character is the limit.

> 
>> through OPAL calls. These calls are made available for the driver by
>> exporting from architecture specific codes.
>>

.../...

>> +
>> +#include <asm/opal.h>
>> +
>> +/*
>> + * 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;
> 
> Please move this to the struct powernv_leds_priv.

Hmmm.. Ok. Will update and use platform_get_drvdata to access platform_get_drvdata.

> 
>> +
>> +/* 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},
>> +};
>> +
>> +/*
>> + * 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;
>> +    char            *loc_code;    /* LED location code */
>> +    int            led_type;    /* OPAL_SLOT_LED_TYPE_* */
>> +    enum led_brightness    value;        /* Brightness value */
>> +    struct mutex        lock;
>> +    struct work_struct    work_led;    /* LED update workqueue */
>> +};
>> +
>> +struct powernv_leds_priv {
>> +    int num_leds;
>> +    struct powernv_led_data powernv_leds[];
>> +};
>> +
>> +static __be64 max_led_type = cpu_to_be64(OPAL_SLOT_LED_TYPE_MAX);
> 
> The C standard prohibits initialization of global objects with non-constant
> values. Section 6.7.8 of the C99 standard states:
> 
> "All the expressions in an initializer for an object that has static storage
> duration shall be constant expressions or string literals."
> 
> Compilation succeeds when using powerpc64-linux-gcc because then
> the following version of macro is used:
> 
> #define cpu_to_be64(x) (x)
> 
> and not
> 
> #define cpu_to_be64(x) swab64(x)
> 
> Please move max_led_type also to the struct powernv_leds_priv
> and initialize it dynamically.

Yeah.. I should have added this to structure itself. Will fix.

> 
>> +
>> +
>> +static inline int sizeof_powernv_leds_priv(int num_leds)
>> +{
>> +    return sizeof(struct powernv_leds_priv) +
>> +        (sizeof(struct powernv_led_data) * num_leds);
>> +}
>> +/* 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)
>> +{
>> +    int rc, token;
>> +    u64 led_mask, led_value = 0;
>> +    __be64 max_type;
>> +    struct opal_msg msg;
>> +    struct device *dev = powernv_led->cdev.dev;
>> +
>> +    /* Prepare for the OPAL call */
>> +    max_type = max_led_type;
>> +    led_mask = OPAL_SLOT_LED_STATE_ON << powernv_led->led_type;
>> +    if (powernv_led->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)
>> +{
>> +    int rc;
>> +    __be64 mask, value, max_type;
>> +    u64 led_mask, led_value;
>> +    struct device *dev = powernv_led->cdev.dev;
>> +
>> +    /* Fetch all LED status */
>> +    mask = cpu_to_be64(0);
>> +    value = cpu_to_be64(0);
>> +    max_type = 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;
>> +}
>> +
>> +/* Execute LED set task for given led classdev */
>> +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);
>> +    mutex_unlock(&powernv_led->lock);
>> +}
>> +
>> +/*
>> + * 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);
>> +
>> +    /* Do not modify LED in unload path */
>> +    if (led_disabled)
>> +        return;
>> +
>> +    /* Prepare the request */
>> +    powernv_led->value = value;
>> +
>> +    /* Schedule the new task */
>> +    schedule_work(&powernv_led->work_led);
>> +}
>> +
>> +/* 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);
>> +}
>> +
>> +
>> +/*
>> + * 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_name, 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;
>> +    }
>> +
>> +    /* Location code of the LED */
>> +    powernv_led->loc_code = kasprintf(GFP_KERNEL, "%s", led_name);
> 
> DT node name is available all the time, you don't need another variable
> for it.

Yes.. But then we have to traverse through  DT node get location code in
powernv_led_get() and powernv_led_set() function. something like
	for_each_child_of_node(led_node, np) {
		if (!strstr(np->name, powernv_led->cdev.name) {
			/* Process get/set LED */
			break;
		}
	}
	
Hence I thought of adding that to structure itself.

-Vasant

> 
>> +    if (!powernv_led->loc_code) {
>> +        dev_err(dev, "%s: Memory allocation failed\n", __func__);
>> +        return -ENOMEM;
>> +    }
>> +
>> +    /* Create the name for classdev */
>> +    powernv_led->cdev.name = devm_kasprintf(dev, GFP_KERNEL, "%s:%s",
>> +                        led_name, led_type_desc);
>> +    if (!powernv_led->cdev.name) {
>> +        dev_err(dev,
>> +            "%s: Memory allocation failed for classdev name\n",
>> +            __func__);
>> +        kfree(powernv_led->loc_code);
>> +        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;
>> +
>> +    mutex_init(&powernv_led->lock);
>> +    INIT_WORK(&powernv_led->work_led, powernv_deferred_led_set);
>> +
>> +    /* 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);
>> +        kfree(powernv_led->loc_code);
>> +        kfree(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_leds_priv *priv, int num_leds)
>> +{
>> +    const char *cur = NULL;
>> +    int i, 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 = &priv->powernv_leds[priv->num_leds++];
>> +            if (priv->num_leds > num_leds) {
>> +                rc = -ENOMEM;
>> +                goto classdev_fail;
>> +            }
>> +            rc = powernv_led_create(dev,
>> +                        powernv_led, np->name, cur);
>> +            if (rc)
>> +                goto classdev_fail;
>> +        } /* while end */
>> +    }
>> +
>> +    platform_set_drvdata(pdev, priv);
>> +    return rc;
>> +
>> +classdev_fail:
>> +    for (i = priv->num_leds - 2; i >= 0; i--) {
>> +        powernv_led = &priv->powernv_leds[i];
>> +        devm_led_classdev_unregister(dev, &powernv_led->cdev);
>> +        kfree(powernv_led->loc_code);
>> +        mutex_destroy(&powernv_led->lock);
>> +    }
>> +
>> +    return rc;
>> +}
>> +
>> +/*
>> + * We want to populate LED device for each LED type. Hence we
>> + * have to calculate count explicitly.
>> + */
>> +static int powernv_leds_count(struct device_node *led_node)
>> +{
>> +    const char *cur = NULL;
>> +    int num_leds = 0;
>> +    struct property *p;
>> +    struct device_node *np;
>> +
>> +    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)
>> +            num_leds++;
>> +    }
>> +
>> +    return num_leds;
>> +}
>> +
>> +/* Platform driver probe */
>> +static int powernv_led_probe(struct platform_device *pdev)
>> +{
>> +    int num_leds;
>> +    struct device_node *led_node;
>> +    struct powernv_leds_priv *priv;
>> +
>> +    led_node = of_find_node_by_path("/ibm,opal/leds");
>> +    if (!led_node) {
>> +        dev_err(&pdev->dev,
>> +            "%s: LED parent device node not found\n", __func__);
>> +        return -EINVAL;
>> +    }
>> +
>> +    num_leds = powernv_leds_count(led_node);
>> +    if (num_leds <= 0) {
>> +        dev_err(&pdev->dev,
>> +            "%s: No location code found under LED node\n",
>> +            __func__);
>> +        return -EINVAL;
>> +    }
>> +
>> +    priv = devm_kzalloc(&pdev->dev,
>> +                sizeof_powernv_leds_priv(num_leds), GFP_KERNEL);
>> +    if (!priv)
>> +        return -ENOMEM;
>> +
>> +    return powernv_led_classdev(pdev, led_node, priv, num_leds);
>> +}
>> +
>> +/* Platform driver remove */
>> +static int powernv_led_remove(struct platform_device *pdev)
>> +{
>> +    int i;
>> +    struct powernv_led_data *powernv_led;
>> +    struct powernv_leds_priv *priv;
>> +
>> +    /* Disable LED operation */
>> +    led_disabled = true;
>> +
>> +    priv = platform_get_drvdata(pdev);
>> +
>> +    for (i = 0; i < priv->num_leds; i++) {
>> +        powernv_led = &priv->powernv_leds[i];
>> +        devm_led_classdev_unregister(&pdev->dev, &powernv_led->cdev);
>> +        flush_work(&powernv_led->work_led);
>> +        kfree(powernv_led->loc_code);
>> +        mutex_destroy(&powernv_led->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");
> 
> If you want to be consistent with what you declare in the beginnig
> then it should be:
> 
> MODULE_LICENSE("GPL v2")

Fixed.

Thanks!
-Vasant