qcacmn: Add QDF cpu hotplug APIs

Currently, there are two consumers of the Linux kernel CPU hotplug APIs.
Besides being problematic for not being operating system agnostic,
different versions of the Linux kernel export different CPU hotplug
APIs. In order to consolidate the various abstractions for different
operating systems and API versions, create a CPU hotplug abstraction in
QDF.

Change-Id: Ib17c6e3ed3a87a90a82d909a6c493360cab27855
CRs-Fixed: 2132632

qdf/inc/qdf_cpuhp.h

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2017 The Linux Foundation. All rights reserved.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for
+ * any purpose with or without fee is hereby granted, provided that the
+ * above copyright notice and this permission notice appear in all
+ * copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/**
+ * DOC: qdf_cpuhp (CPU hotplug)
+ * QCA driver framework (QDF) CPU hotplug APIs
+ */
+
+#ifndef __QDF_CPUHP_H
+#define __QDF_CPUHP_H
+
+#include "qdf_status.h"
+#include "qdf_types.h"
+
+/**
+ * struct qdf_cpuhp_handler - an opaque hotplug event registration handle
+ */
+struct qdf_cpuhp_handler;
+
+typedef void (*qdf_cpuhp_callback)(void *context, uint32_t cpu);
+
+#ifdef QCA_CONFIG_SMP
+/**
+ * qdf_cpuhp_init() - Initialize the CPU hotplug event infrastructure
+ *
+ * To be called once, globally.
+ *
+ * Return: None
+ */
+QDF_STATUS qdf_cpuhp_init(void);
+
+/**
+ * qdf_cpuhp_deinit() - De-initialize the CPU hotplug event infrastructure
+ *
+ * To be called once, globally.
+ *
+ * Return: None
+ */
+QDF_STATUS qdf_cpuhp_deinit(void);
+
+/**
+ * qdf_cpuhp_register() - Register for CPU up/down event notifications
+ * @handler: a double pointer to the event registration handle to allocate
+ * @context: an opaque context to pass back to event listeners
+ * @up_callback: the function pointer to invoke for CPU up events
+ * @down_callback: the function pointer to invoke for CPU down events
+ *
+ * "Up" happens just after the CPU is up. Inversely, "down" happens just before
+ * the CPU goes down.
+ *
+ * @handler will point to a valid memory address on success, or NULL on failure.
+ *
+ * Return: QDF_STATUS
+ */
+QDF_STATUS qdf_cpuhp_register(struct qdf_cpuhp_handler **handler,
+			      void *context,
+			      qdf_cpuhp_callback up_callback,
+			      qdf_cpuhp_callback down_callback);
+
+/**
+ * qdf_cpuhp_unregister() - Un-register for CPU up/down event notifications
+ * @handler: a double pointer to the event registration handle to de-allocate
+ *
+ * @handler point to NULL upon completion
+ *
+ * Return: None
+ */
+void qdf_cpuhp_unregister(struct qdf_cpuhp_handler **handler);
+#else
+QDF_STATUS qdf_cpuhp_init(void)
+{
+	return QDF_STATUS_SUCCESS;
+}
+
+QDF_STATUS qdf_cpuhp_deinit(void)
+{
+	return QDF_STATUS_SUCCESS;
+}
+
+QDF_STATUS qdf_cpuhp_register(struct qdf_cpuhp_handler **handler,
+			      void *context,
+			      qdf_cpuhp_callback up_callback,
+			      qdf_cpuhp_callback down_callback)
+{
+	return QDF_STATUS_SUCCESS;
+}
+
+void qdf_cpuhp_unregister(struct qdf_cpuhp_handler **handler) {}
+#endif /* QCA_CONFIG_SMP */
+
+#endif /* __QDF_CPUHP_H */