Subject: [PATCH v2 2/2] leds/powernv: Add driver for PowerNV platform

From: Vasant Hegde <[email-masked]>
Date: Fri, 20 Mar 2015 16:34:53 +0530

From: Anshuman Khandual <[email-masked]>

This patch implements LED driver for PowerNV platform using the existing
generic LED class framework. It 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.

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.

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.

All the system LEDs can be found in the same regular path /sys/class/leds/.
There are two different kind of LEDs present for the same location code,
one being the identify indicator and other one being the fault indicator.
We don't use LED colors. Hence 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 for any turned off LED.

Signed-off-by: Anshuman Khandual <[email-masked]>
Signed-off-by: Vasant Hegde <[email-masked]>
Acked-by: Stewart Smith <[email-masked]>
Tested-by: Stewart Smith <[email-masked]>
---
Changes in v2:
  - Added System Attention indicator support
  - Moved common code to powernv_led_set_queue()

-Vasant

 arch/powerpc/platforms/powernv/opal.c |   12 +
 drivers/leds/Kconfig                  |    9 
 drivers/leds/Makefile                 |    1 
 drivers/leds/leds-powernv.c           |  620 +++++++++++++++++++++++++++++++++
 4 files changed, 641 insertions(+), 1 deletion(-)
 create mode 100644 drivers/leds/leds-powernv.c

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 142a08a..fbfd9c1 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -746,7 +746,7 @@ static void __init opal_irq_init(struct device_node *dn)
 
 static int __init opal_init(void)
 {
-	struct device_node *np, *consoles;
+	struct device_node *np, *consoles, *led;
 	int rc;
 
 	opal_node = of_find_node_by_path("/ibm,opal");
@@ -772,6 +772,13 @@ static int __init opal_init(void)
 	/* Create i2c platform devices */
 	opal_i2c_create_devs();
 
+	/* Create led platform devices */
+	led = of_find_node_by_path("/ibm,opal/led");
+	if (led) {
+		of_platform_device_create(led, "opal_led", NULL);
+		of_node_put(led);
+	}
+
 	/* Find all OPAL interrupts and request them */
 	opal_irq_init(opal_node);
 
@@ -904,3 +911,6 @@ EXPORT_SYMBOL_GPL(opal_rtc_write);
 EXPORT_SYMBOL_GPL(opal_tpo_read);
 EXPORT_SYMBOL_GPL(opal_tpo_write);
 EXPORT_SYMBOL_GPL(opal_i2c_request);
+/* Export these symbols for PowerNV LED class driver */
+EXPORT_SYMBOL_GPL(opal_leds_get_ind);
+EXPORT_SYMBOL_GPL(opal_leds_set_ind);
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 25b320d..a93223c 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -508,6 +508,15 @@ 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
+	help
+	  This option enables support for the system LEDs present on
+	  PowerNV platforms. Say 'y' to enable this support in kernel.
+	  Say 'm' enable this support as module.
+
 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..0c9f958
--- /dev/null
+++ b/drivers/leds/leds-powernv.c
@@ -0,0 +1,620 @@
+/*
+ * PowerNV LED Driver
+ *
+ * Copyright IBM Corp. 2015
+ *
+ * Author: Anshuman Khandual <[email-masked]>
+ * Author: Vasant Hegde <[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.
+ */
+
+#define PREFIX		"POWERNV_LED"
+#define pr_fmt(fmt)	PREFIX ": " fmt
+
+#include <linux/platform_device.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+
+#include <asm/opal.h>
+
+#define LED_STR_ATTENTION	":ATTENTION"
+#define LED_STR_IDENT		":IDENTIFY"
+#define LED_STR_FAULT		":FAULT"
+
+/*
+ * LED operation state
+ *
+ * led_classdev_unregister resets the brightness values. However
+ * we want to retain the LED state across boot. Hence disable
+ * LED operation before calling led_classdev_unregister.
+ */
+static bool led_disabled = false;
+
+/*
+ * LED type map
+ *
+ * Converts LED event type into it's description.
+ */
+static const char *led_type_map[OPAL_SLOT_LED_TYPE_MAX] = {
+	"Attention", "Identify", "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. A lot of work queue
+ * tasks attempting to set the LED states can prevent each other from
+ * completing their task. So there is a need to restrict the total number
+ * of work queue tasks at any point in time related to LED.
+ */
+#define MAX_LED_REQ_COUNT	100
+static int led_req_count;
+
+/*
+ * LED classdev
+ *
+ * Each LED classdev structure registered on the platform will be put into
+ * a list which will be eventually used for de-registration purpose.
+ */
+struct powernv_led {
+	struct led_classdev cdev;
+	struct list_head    link;
+};
+static LIST_HEAD(powernv_led_list);
+static DEFINE_SPINLOCK(powernv_led_spinlock);
+
+/*
+ * LED set state command
+ *
+ * Each set LED state request will be saved and put into a list to be
+ * processed later by a work queue task.
+ */
+struct powernv_led_cmd {
+	struct led_classdev *led_cdev; /* Points to classdev structure */
+	enum led_brightness value;     /* Brightness value */
+	u64                 led_type;  /* Identify or Fault */
+	struct list_head    link;
+};
+static LIST_HEAD(powernv_led_cmd_list);
+static DEFINE_SPINLOCK(powernv_led_cmd_spinlock);
+
+/*
+ * LED set state task
+ *
+ * Each set LED state request added into the request list for post
+ * processing will be followed by one of this structure. The work
+ * struct here will be scheduled on the global work queue to process
+ * one of the requests from the request list. Though the order of
+ * execution is not guaraneteed.
+ */
+struct powernv_led_work {
+	struct work_struct work;      /* Individual task */
+	bool               deletion;  /* Need deletion */
+	struct list_head   link;
+};
+static LIST_HEAD(powernv_led_work_list);
+static DEFINE_SPINLOCK(powernv_led_work_spinlock);
+
+/*
+ * powernv_led_compact_work_list
+ *
+ * This function goes through the entire list of scheduled powernv_led_work
+ * nodes and removes the nodes which have already processed one set LED
+ * state request from request list and has been marked for deletion. This is
+ * essential for cleaning the list before adding new elements into it. This
+ * also tracks the total number of pending tasks. Once it reaches the
+ * threshold the function will throttle till all the scheduled tasks completes
+ * execution during which the user space thread will block and will be
+ * prevented from queuing up more LED state change requests.
+ */
+static void powernv_led_compact_work_list(void)
+{
+	struct powernv_led_work *pwork, *pwork_ne;
+	unsigned long flags;
+
+	spin_lock_irqsave(&powernv_led_work_spinlock, flags);
+	led_req_count = 0;
+	list_for_each_entry_safe(pwork, pwork_ne,
+				 &powernv_led_work_list, link) {
+		if (pwork->deletion) {
+			list_del(&pwork->link);
+			kfree(pwork);
+			continue;
+		}
+		led_req_count++;
+	}
+	spin_unlock_irqrestore(&powernv_led_work_spinlock, flags);
+
+	/* Throttle if the threshold reached */
+	if (led_req_count == MAX_LED_REQ_COUNT) {
+		list_for_each_entry(pwork, &powernv_led_work_list, link)
+			flush_work(&pwork->work);
+	}
+}
+
+/*
+ * powernv_led_set
+ *
+ * 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) {
+		pr_err(PREFIX "Memory allocation failed at %s\n", __func__);
+		return;
+	}
+
+	switch (led_type) {
+	case OPAL_SLOT_LED_TYPE_ATTN:
+		loc_code[strlen(loc_code) - strlen(LED_STR_ATTENTION)] = '\0';
+		break;
+	case OPAL_SLOT_LED_TYPE_ID:
+		loc_code[strlen(loc_code) - strlen(LED_STR_IDENT)] = '\0';
+		break;
+	case OPAL_SLOT_LED_TYPE_FAULT:
+		loc_code[strlen(loc_code) - strlen(LED_STR_FAULT)] = '\0';
+		break;
+	default:	/* Unknown LED type */
+		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)
+			pr_err("%s: Couldn't get the token, returning\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) {
+		pr_err("OPAL call opal_leds_set_ind failed for %s with %d\n",
+		       loc_code, rc);
+		goto out_token;
+	}
+
+	rc = opal_async_wait_response(token, &msg);
+	if (rc) {
+		pr_err("%s: Failed to wait for the async response, %d\n",
+			__func__, rc);
+		goto out_token;
+	}
+
+	rc = be64_to_cpu(msg.params[1]);
+	if (rc != OPAL_SUCCESS)
+		pr_err("Async call returned with failed status: %d\n", rc);
+
+out_token:
+	opal_async_release_token(token);
+
+out_loc:
+	kfree(loc_code);
+}
+
+/*
+ * powernv_led_get
+ *
+ * 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) {
+		pr_err("Memory allocation failed at: %s\n", __func__);
+		return -ENOMEM;
+	}
+
+	switch (led_type) {
+	case OPAL_SLOT_LED_TYPE_ATTN:
+		loc_code[strlen(loc_code) - strlen(LED_STR_ATTENTION)] = '\0';
+		break;
+	case OPAL_SLOT_LED_TYPE_ID:
+		loc_code[strlen(loc_code) - strlen(LED_STR_IDENT)] = '\0';
+		break;
+	case OPAL_SLOT_LED_TYPE_FAULT:
+		loc_code[strlen(loc_code) - strlen(LED_STR_FAULT)] = '\0';
+		break;
+	default:	/* Unsupported LED type */
+		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) {
+		pr_err("OPAL call opal_leds_get_ind failed with %d\n", 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)) {
+		pr_err("%s LED status not available for %s\n",
+		       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;
+}
+
+/*
+ * powernv_led_work_func
+ *
+ * This the function which will be executed by any LED work task on the
+ * global work queue. This function de-queues one of the request node
+ * from the request list, processes it and then deletes the request node.
+ * This also accesses it's own work list node and sets the deletion flag
+ * in there making itself a candidate for removal the next time the
+ * compact function gets called.
+ */
+static void powernv_led_work_func(struct work_struct *work)
+{
+	struct powernv_led_work *pwork;
+	struct powernv_led_cmd *req;
+	unsigned long flags;
+
+	/* De-queue one request, process it and then delete */
+	spin_lock_irqsave(&powernv_led_cmd_spinlock, flags);
+	if (list_empty(&powernv_led_cmd_list)) {
+		pr_err("Request list empty, but work queue task queued\n");
+		spin_unlock_irqrestore(&powernv_led_cmd_spinlock, flags);
+		return;
+	}
+
+	req = list_first_entry(&powernv_led_cmd_list,
+			       struct powernv_led_cmd, link);
+	list_del(&req->link);
+	spin_unlock_irqrestore(&powernv_led_cmd_spinlock, flags);
+
+	powernv_led_set(req->led_cdev, req->value, req->led_type);
+	kfree(req);
+
+	/* Mark the work queue task for deletion */
+	spin_lock_irqsave(&powernv_led_work_spinlock, flags);
+	pwork = container_of(work, struct powernv_led_work, work);
+	pwork->deletion = true;
+	spin_unlock_irqrestore(&powernv_led_work_spinlock, flags);
+}
+
+/*
+ * powernv_led_set_queue
+ *
+ * LED classdev 'brightness_set' function for LEDs
+ */
+static void powernv_led_set_queue(struct led_classdev *led_cdev,
+				  enum led_brightness value, u64 led_type)
+{
+	struct powernv_led_work *pwork;
+	struct powernv_led_cmd *attn;
+	unsigned long flags;
+
+	if (led_disabled)
+		return;
+
+	/* Allocate the request */
+	attn = kzalloc(sizeof(struct powernv_led_cmd), GFP_KERNEL);
+	if (!attn) {
+		pr_err("Memory allocation failed at: %s\n", __func__);
+		return;
+	}
+
+	/* Allocate the work */
+	pwork = kzalloc(sizeof(struct powernv_led_work), GFP_KERNEL);
+	if (!pwork) {
+		pr_err("Memory allocation failed at: %s\n", __func__);
+		kfree(attn);
+		return;
+	}
+
+	/* Prepare the request */
+	attn->led_cdev = led_cdev;
+	attn->value = value;
+	attn->led_type = led_type;
+
+	/* Queue the request */
+	spin_lock_irqsave(&powernv_led_cmd_spinlock, flags);
+	list_add_tail(&attn->link, &powernv_led_cmd_list);
+	spin_unlock_irqrestore(&powernv_led_cmd_spinlock, flags);
+
+	/* Compact the work list */
+	powernv_led_compact_work_list();
+
+	/* Add the new task into the work list */
+	spin_lock_irqsave(&powernv_led_work_spinlock, flags);
+	list_add_tail(&pwork->link, &powernv_led_work_list);
+	spin_unlock_irqrestore(&powernv_led_work_spinlock, flags);
+
+	/* Schedule the new task */
+	INIT_WORK(&pwork->work, powernv_led_work_func);
+	schedule_work(&pwork->work);
+}
+/*
+ * powernv_led_set_attn
+ *
+ * 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);
+}
+
+/*
+ * powernv_led_get_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);
+}
+
+/*
+ * powernv_led_set_ident
+ *
+ * LED classdev 'brightness_set' function for identify 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);
+}
+
+/*
+ * powernv_led_get_ident
+ *
+ * LED classdev 'brightness_get' function for identify 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);
+}
+
+/*
+ * powernv_led_set_fault
+ *
+ * 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);
+}
+
+/*
+ * powernv_led_get_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);
+}
+
+/*
+ * has_led_type
+ *
+ * This function verifies whether the child LED device node supports certain
+ * type of LED or not. This will be used to register LEDclassdev structures
+ * for that particual type of LED for a given device tree node.
+ */
+static bool has_led_type(struct device_node *cled, const char *led_type)
+{
+	bool result = false;
+
+	if (of_property_match_string(cled, "led-types", led_type) >= 0)
+		result = true;
+
+	return result;
+}
+
+/*
+ * power_led_classdev
+ *
+ * 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 *cled, u64 led_type)
+{
+	int rc;
+	unsigned long flags;
+	struct powernv_led *cpled;
+
+	cpled = kzalloc(sizeof(struct powernv_led), GFP_KERNEL);
+	if (!cpled) {
+		pr_err("Memory allocation failed at %s\n", __func__);
+		return -ENOMEM;
+	}
+
+	/* Create the name for classdev */
+	switch (led_type) {
+	case OPAL_SLOT_LED_TYPE_ATTN:
+		cpled->cdev.name = kasprintf(GFP_KERNEL, "%s%s",
+					     cled->name, LED_STR_ATTENTION);
+		cpled->cdev.brightness_set = powernv_led_set_attn;
+		cpled->cdev.brightness_get = powernv_led_get_attn;
+		break;
+	case OPAL_SLOT_LED_TYPE_ID:
+		cpled->cdev.name = kasprintf(GFP_KERNEL, "%s%s",
+					     cled->name, LED_STR_IDENT);
+		cpled->cdev.brightness_set = powernv_led_set_ident;
+		cpled->cdev.brightness_get = powernv_led_get_ident;
+		break;
+	case OPAL_SLOT_LED_TYPE_FAULT:
+		cpled->cdev.name = kasprintf(GFP_KERNEL, "%s%s",
+						cled->name, LED_STR_FAULT);
+		cpled->cdev.brightness_set = powernv_led_set_fault;
+		cpled->cdev.brightness_get = powernv_led_get_fault;
+		break;
+	default: /* Unsupported LED type */
+		return -EINVAL;
+	}
+
+	if (!cpled->cdev.name) {
+		pr_err("Memory allocation failed for classdev name\n");
+		return -ENOMEM;
+	}
+
+	cpled->cdev.brightness = LED_OFF;
+	cpled->cdev.max_brightness = LED_FULL;
+	cpled->cdev.flags = LED_CORE_SUSPENDRESUME;
+
+	/* Register the classdev */
+	rc = led_classdev_register(&pdev->dev, &cpled->cdev);
+	if (rc) {
+		pr_err("Classdev registration failed for %s\n",
+		       cpled->cdev.name);
+	} else {
+		spin_lock_irqsave(&powernv_led_spinlock, flags);
+		list_add_tail(&cpled->link, &powernv_led_list);
+		spin_unlock_irqrestore(&powernv_led_spinlock, flags);
+		pr_debug("Classdev registration successful for %s\n",
+			 cpled->cdev.name);
+	}
+	return rc;
+}
+
+/* Platform driver probe */
+static int powernv_led_probe(struct platform_device *pdev)
+{
+	struct device_node *led, *cled;
+	int rc = 0;
+
+	led = of_find_node_by_path("/ibm,opal/led");
+	if (!led) {
+		pr_err("LED parent device node not found\n");
+		return -EINVAL;
+	}
+
+	for_each_child_of_node(led, cled) {
+		if (has_led_type(cled, LED_TYPE_ATTENTION))
+			rc = power_led_classdev(pdev, cled,
+						OPAL_SLOT_LED_TYPE_ATTN);
+
+		if (has_led_type(cled, LED_TYPE_IDENTIFY))
+			rc = power_led_classdev(pdev, cled,
+						OPAL_SLOT_LED_TYPE_ID);
+
+		if (has_led_type(cled, LED_TYPE_FAULT))
+			rc = power_led_classdev(pdev, cled,
+						OPAL_SLOT_LED_TYPE_FAULT);
+	}
+	return rc;
+}
+
+/* Platform driver remove */
+static int powernv_led_remove(struct platform_device *pdev)
+{
+	struct powernv_led *pled;
+	struct powernv_led_work *pwork;
+	unsigned long flags;
+
+	/* Disable LED operation */
+	led_disabled = true;
+
+	pr_info("Unregister all classdev structures\n");
+	list_for_each_entry(pled, &powernv_led_list, link)
+		led_classdev_unregister(&pled->cdev);
+
+	pr_info("Wait for all work tasks to finish\n");
+	list_for_each_entry(pwork, &powernv_led_work_list, link)
+		flush_work(&pwork->work);
+
+	/* Free nodes from the work list */
+	powernv_led_compact_work_list();
+
+	/* Free nodes from the classdev list */
+	spin_lock_irqsave(&powernv_led_spinlock, flags);
+	while (!list_empty(&powernv_led_list)) {
+		pled = list_first_entry(&powernv_led_list,
+					struct powernv_led, link);
+		list_del(&pled->link);
+		kfree(pled);
+	}
+	spin_unlock_irqrestore(&powernv_led_spinlock, flags);
+
+	/* Check for memory leaks */
+	if (!list_empty(&powernv_led_work_list))
+		pr_warn("Work list not empty, memory leak\n");
+
+	if (!list_empty(&powernv_led_cmd_list))
+		pr_warn("Request list not empty, memory leak\n");
+
+	if (!list_empty(&powernv_led_list))
+		pr_warn("Classdev list not empty, memory leak\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("Anshuman Khandual <[email-masked]>");