Merge "Merge branch 'v4.4-16.09-android-tmp' into lsk-v4.4-16.09-android"

10 files changed, 603 insertions, 50 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 9f0d9b7b7e17..ca092ef75cfe 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -555,6 +555,11 @@ config QPNP_MISC
 	  peripheral. The MISC peripheral holds the USB ID interrupt
 	  and the driver provides an API to check if this interrupt
 	  is available on the current PMIC chip.
+config MEMORY_STATE_TIME
+	tristate "Memory freq/bandwidth time statistics"
+	depends on PROFILING
+	help
+	  Memory time statistics exported to /sys/kernel/memory_state_time
 
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 6acb70964fb8..40b7e3b603e2 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -64,3 +64,4 @@ obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_UID_CPUTIME) += uid_cputime.o
 obj-y				+= qcom/
 obj-$(CONFIG_QPNP_MISC) 	+= qpnp-misc.o
+obj-$(CONFIG_MEMORY_STATE_TIME) += memory_state_time.o
diff --git a/drivers/misc/cxl/Makefile b/drivers/misc/cxl/Makefile
index 6982f603fadc..ab6f392d3504 100644
--- a/drivers/misc/cxl/Makefile
+++ b/drivers/misc/cxl/Makefile
@@ -1,4 +1,4 @@
-ccflags-y := -Werror -Wno-unused-const-variable
+ccflags-y := -Werror $(call cc-disable-warning, unused-const-variable)
 
 cxl-y				+= main.o file.o irq.o fault.o native.o
 cxl-y				+= context.o sysfs.o debugfs.o pci.o trace.o
diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index 103baf0e0c5b..ea3eeb7011e1 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -25,7 +25,6 @@ struct cxl_context *cxl_dev_context_init(struct pci_dev *dev)
 
 	afu = cxl_pci_to_afu(dev);
 
-	get_device(&afu->dev);
 	ctx = cxl_context_alloc();
 	if (IS_ERR(ctx)) {
 		rc = PTR_ERR(ctx);
@@ -61,7 +60,6 @@ err_mapping:
 err_ctx:
 	kfree(ctx);
 err_dev:
-	put_device(&afu->dev);
 	return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_GPL(cxl_dev_context_init);
@@ -87,8 +85,6 @@ int cxl_release_context(struct cxl_context *ctx)
 	if (ctx->status >= STARTED)
 		return -EBUSY;
 
-	put_device(&ctx->afu->dev);
-
 	cxl_context_free(ctx);
 
 	return 0;
@@ -176,7 +172,7 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed,
 
 	if (task) {
 		ctx->pid = get_task_pid(task, PIDTYPE_PID);
-		get_pid(ctx->pid);
+		ctx->glpid = get_task_pid(task->group_leader, PIDTYPE_PID);
 		kernel = false;
 	}
 
diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 2faa1270d085..262b88eac414 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -42,7 +42,7 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master,
 	spin_lock_init(&ctx->sste_lock);
 	ctx->afu = afu;
 	ctx->master = master;
-	ctx->pid = NULL; /* Set in start work ioctl */
+	ctx->pid = ctx->glpid = NULL; /* Set in start work ioctl */
 	mutex_init(&ctx->mapping_lock);
 	ctx->mapping = mapping;
 
@@ -97,6 +97,12 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master,
 	ctx->pe = i;
 	ctx->elem = &ctx->afu->spa[i];
 	ctx->pe_inserted = false;
+
+	/*
+	 * take a ref on the afu so that it stays alive at-least till
+	 * this context is reclaimed inside reclaim_ctx.
+	 */
+	cxl_afu_get(afu);
 	return 0;
 }
 
@@ -211,7 +217,11 @@ int __detach_context(struct cxl_context *ctx)
 	WARN_ON(cxl_detach_process(ctx) &&
 		cxl_adapter_link_ok(ctx->afu->adapter));
 	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
+
+	/* release the reference to the group leader and mm handling pid */
 	put_pid(ctx->pid);
+	put_pid(ctx->glpid);
+
 	cxl_ctx_put();
 	return 0;
 }
@@ -278,6 +288,9 @@ static void reclaim_ctx(struct rcu_head *rcu)
 	if (ctx->irq_bitmap)
 		kfree(ctx->irq_bitmap);
 
+	/* Drop ref to the afu device taken during cxl_context_init */
+	cxl_afu_put(ctx->afu);
+
 	kfree(ctx);
 }
 
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index 0cfb9c129f27..a521bc72cec2 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -403,6 +403,18 @@ struct cxl_afu {
 	bool enabled;
 };
 
+/* AFU refcount management */
+static inline struct cxl_afu *cxl_afu_get(struct cxl_afu *afu)
+{
+
+	return (get_device(&afu->dev) == NULL) ? NULL : afu;
+}
+
+static inline void  cxl_afu_put(struct cxl_afu *afu)
+{
+	put_device(&afu->dev);
+}
+
 
 struct cxl_irq_name {
 	struct list_head list;
@@ -433,6 +445,9 @@ struct cxl_context {
 	unsigned int sst_size, sst_lru;
 
 	wait_queue_head_t wq;
+	/* pid of the group leader associated with the pid */
+	struct pid *glpid;
+	/* use mm context associated with this pid for ds faults */
 	struct pid *pid;
 	spinlock_t lock; /* Protects pending_irq_mask, pending_fault and fault_addr */
 	/* Only used in PR mode */
diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c
index 25a5418c55cb..81c3f75b7330 100644
--- a/drivers/misc/cxl/fault.c
+++ b/drivers/misc/cxl/fault.c
@@ -166,13 +166,92 @@ static void cxl_handle_page_fault(struct cxl_context *ctx,
 	cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
 }
 
+/*
+ * Returns the mm_struct corresponding to the context ctx via ctx->pid
+ * In case the task has exited we use the task group leader accessible
+ * via ctx->glpid to find the next task in the thread group that has a
+ * valid  mm_struct associated with it. If a task with valid mm_struct
+ * is found the ctx->pid is updated to use the task struct for subsequent
+ * translations. In case no valid mm_struct is found in the task group to
+ * service the fault a NULL is returned.
+ */
+static struct mm_struct *get_mem_context(struct cxl_context *ctx)
+{
+	struct task_struct *task = NULL;
+	struct mm_struct *mm = NULL;
+	struct pid *old_pid = ctx->pid;
+
+	if (old_pid == NULL) {
+		pr_warn("%s: Invalid context for pe=%d\n",
+			 __func__, ctx->pe);
+		return NULL;
+	}
+
+	task = get_pid_task(old_pid, PIDTYPE_PID);
+
+	/*
+	 * pid_alive may look racy but this saves us from costly
+	 * get_task_mm when the task is a zombie. In worst case
+	 * we may think a task is alive, which is about to die
+	 * but get_task_mm will return NULL.
+	 */
+	if (task != NULL && pid_alive(task))
+		mm = get_task_mm(task);
+
+	/* release the task struct that was taken earlier */
+	if (task)
+		put_task_struct(task);
+	else
+		pr_devel("%s: Context owning pid=%i for pe=%i dead\n",
+			__func__, pid_nr(old_pid), ctx->pe);
+
+	/*
+	 * If we couldn't find the mm context then use the group
+	 * leader to iterate over the task group and find a task
+	 * that gives us mm_struct.
+	 */
+	if (unlikely(mm == NULL && ctx->glpid != NULL)) {
+
+		rcu_read_lock();
+		task = pid_task(ctx->glpid, PIDTYPE_PID);
+		if (task)
+			do {
+				mm = get_task_mm(task);
+				if (mm) {
+					ctx->pid = get_task_pid(task,
+								PIDTYPE_PID);
+					break;
+				}
+				task = next_thread(task);
+			} while (task && !thread_group_leader(task));
+		rcu_read_unlock();
+
+		/* check if we switched pid */
+		if (ctx->pid != old_pid) {
+			if (mm)
+				pr_devel("%s:pe=%i switch pid %i->%i\n",
+					 __func__, ctx->pe, pid_nr(old_pid),
+					 pid_nr(ctx->pid));
+			else
+				pr_devel("%s:Cannot find mm for pid=%i\n",
+					 __func__, pid_nr(old_pid));
+
+			/* drop the reference to older pid */
+			put_pid(old_pid);
+		}
+	}
+
+	return mm;
+}
+
+
+
 void cxl_handle_fault(struct work_struct *fault_work)
 {
 	struct cxl_context *ctx =
 		container_of(fault_work, struct cxl_context, fault_work);
 	u64 dsisr = ctx->dsisr;
 	u64 dar = ctx->dar;
-	struct task_struct *task = NULL;
 	struct mm_struct *mm = NULL;
 
 	if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr ||
@@ -195,17 +274,17 @@ void cxl_handle_fault(struct work_struct *fault_work)
 		"DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar);
 
 	if (!ctx->kernel) {
-		if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
-			pr_devel("cxl_handle_fault unable to get task %i\n",
-				 pid_nr(ctx->pid));
+
+		mm = get_mem_context(ctx);
+		/* indicates all the thread in task group have exited */
+		if (mm == NULL) {
+			pr_devel("%s: unable to get mm for pe=%d pid=%i\n",
+				 __func__, ctx->pe, pid_nr(ctx->pid));
 			cxl_ack_ae(ctx);
 			return;
-		}
-		if (!(mm = get_task_mm(task))) {
-			pr_devel("cxl_handle_fault unable to get mm %i\n",
-				 pid_nr(ctx->pid));
-			cxl_ack_ae(ctx);
-			goto out;
+		} else {
+			pr_devel("Handling page fault for pe=%d pid=%i\n",
+				 ctx->pe, pid_nr(ctx->pid));
 		}
 	}
 
@@ -218,33 +297,22 @@ void cxl_handle_fault(struct work_struct *fault_work)
 
 	if (mm)
 		mmput(mm);
-out:
-	if (task)
-		put_task_struct(task);
 }
 
 static void cxl_prefault_one(struct cxl_context *ctx, u64 ea)
 {
-	int rc;
-	struct task_struct *task;
 	struct mm_struct *mm;
 
-	if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
-		pr_devel("cxl_prefault_one unable to get task %i\n",
-			 pid_nr(ctx->pid));
-		return;
-	}
-	if (!(mm = get_task_mm(task))) {
+	mm = get_mem_context(ctx);
+	if (mm == NULL) {
 		pr_devel("cxl_prefault_one unable to get mm %i\n",
 			 pid_nr(ctx->pid));
-		put_task_struct(task);
 		return;
 	}
 
-	rc = cxl_fault_segment(ctx, mm, ea);
+	cxl_fault_segment(ctx, mm, ea);
 
 	mmput(mm);
-	put_task_struct(task);
 }
 
 static u64 next_segment(u64 ea, u64 vsid)
@@ -263,18 +331,13 @@ static void cxl_prefault_vma(struct cxl_context *ctx)
 	struct copro_slb slb;
 	struct vm_area_struct *vma;
 	int rc;
-	struct task_struct *task;
 	struct mm_struct *mm;
 
-	if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
-		pr_devel("cxl_prefault_vma unable to get task %i\n",
-			 pid_nr(ctx->pid));
-		return;
-	}
-	if (!(mm = get_task_mm(task))) {
+	mm = get_mem_context(ctx);
+	if (mm == NULL) {
 		pr_devel("cxl_prefault_vm unable to get mm %i\n",
 			 pid_nr(ctx->pid));
-		goto out1;
+		return;
 	}
 
 	down_read(&mm->mmap_sem);
@@ -295,8 +358,6 @@ static void cxl_prefault_vma(struct cxl_context *ctx)
 	up_read(&mm->mmap_sem);
 
 	mmput(mm);
-out1:
-	put_task_struct(task);
 }
 
 void cxl_prefault(struct cxl_context *ctx, u64 wed)
diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index 7ccd2998be92..783337d22f36 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -67,7 +67,13 @@ static int __afu_open(struct inode *inode, struct file *file, bool master)
 		spin_unlock(&adapter->afu_list_lock);
 		goto err_put_adapter;
 	}
-	get_device(&afu->dev);
+
+	/*
+	 * taking a ref to the afu so that it doesn't go away
+	 * for rest of the function. This ref is released before
+	 * we return.
+	 */
+	cxl_afu_get(afu);
 	spin_unlock(&adapter->afu_list_lock);
 
 	if (!afu->current_mode)
@@ -90,13 +96,12 @@ static int __afu_open(struct inode *inode, struct file *file, bool master)
 	file->private_data = ctx;
 	cxl_ctx_get();
 
-	/* Our ref on the AFU will now hold the adapter */
-	put_device(&adapter->dev);
-
-	return 0;
+	/* indicate success */
+	rc = 0;
 
 err_put_afu:
-	put_device(&afu->dev);
+	/* release the ref taken earlier */
+	cxl_afu_put(afu);
 err_put_adapter:
 	put_device(&adapter->dev);
 	return rc;
@@ -131,8 +136,6 @@ int afu_release(struct inode *inode, struct file *file)
 		mutex_unlock(&ctx->mapping_lock);
 	}
 
-	put_device(&ctx->afu->dev);
-
 	/*
 	 * At this this point all bottom halfs have finished and we should be
 	 * getting no more IRQs from the hardware for this context.  Once it's
@@ -198,8 +201,12 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
 	 * where a process (master, some daemon, etc) has opened the chardev on
 	 * behalf of another process, so the AFU's mm gets bound to the process
 	 * that performs this ioctl and not the process that opened the file.
+	 * Also we grab the PID of the group leader so that if the task that
+	 * has performed the attach operation exits the mm context of the
+	 * process is still accessible.
 	 */
-	ctx->pid = get_pid(get_task_pid(current, PIDTYPE_PID));
+	ctx->pid = get_task_pid(current, PIDTYPE_PID);
+	ctx->glpid = get_task_pid(current->group_leader, PIDTYPE_PID);
 
 	trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr);
 
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index be2c8e248e2e..0c6c17a1c59e 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -138,6 +138,7 @@ static const struct pci_device_id cxl_pci_tbl[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x0477), },
 	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x044b), },
 	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x04cf), },
+	{ PCI_DEVICE(PCI_VENDOR_ID_IBM, 0x0601), },
 	{ PCI_DEVICE_CLASS(0x120000, ~0), },
 
 	{ }
diff --git a/drivers/misc/memory_state_time.c b/drivers/misc/memory_state_time.c
new file mode 100644
index 000000000000..34c797a06a31
--- /dev/null
+++ b/drivers/misc/memory_state_time.c
@@ -0,0 +1,454 @@
+/* drivers/misc/memory_state_time.c
+ *
+ * Copyright (C) 2016 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/hashtable.h>
+#include <linux/kconfig.h>
+#include <linux/kernel.h>
+#include <linux/kobject.h>
+#include <linux/memory-state-time.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/time.h>
+#include <linux/timekeeping.h>
+#include <linux/workqueue.h>
+
+#define KERNEL_ATTR_RO(_name) \
+static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
+
+#define KERNEL_ATTR_RW(_name) \
+static struct kobj_attribute _name##_attr = \
+	__ATTR(_name, 0644, _name##_show, _name##_store)
+
+#define FREQ_HASH_BITS 4
+DECLARE_HASHTABLE(freq_hash_table, FREQ_HASH_BITS);
+
+static DEFINE_MUTEX(mem_lock);
+
+#define TAG "memory_state_time"
+#define BW_NODE "/soc/memory-state-time"
+#define FREQ_TBL "freq-tbl"
+#define BW_TBL "bw-buckets"
+#define NUM_SOURCES "num-sources"
+
+#define LOWEST_FREQ 2
+
+static int curr_bw;
+static int curr_freq;
+static u32 *bw_buckets;
+static u32 *freq_buckets;
+static int num_freqs;
+static int num_buckets;
+static int registered_bw_sources;
+static u64 last_update;
+static bool init_success;
+static struct workqueue_struct *memory_wq;
+static u32 num_sources = 10;
+static int *bandwidths;
+
+struct freq_entry {
+	int freq;
+	u64 *buckets; /* Bandwidth buckets. */
+	struct hlist_node hash;
+};
+
+struct queue_container {
+	struct work_struct update_state;
+	int value;
+	u64 time_now;
+	int id;
+	struct mutex *lock;
+};
+
+static int find_bucket(int bw)
+{
+	int i;
+
+	if (bw_buckets != NULL) {
+		for (i = 0; i < num_buckets; i++) {
+			if (bw_buckets[i] > bw) {
+				pr_debug("Found bucket %d for bandwidth %d\n",
+					i, bw);
+				return i;
+			}
+		}
+		return num_buckets - 1;
+	}
+	return 0;
+}
+
+static u64 get_time_diff(u64 time_now)
+{
+	u64 ms;
+
+	ms = time_now - last_update;
+	last_update = time_now;
+	return ms;
+}
+
+static ssize_t show_stat_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	int i, j;
+	int len = 0;
+	struct freq_entry *freq_entry;
+
+	for (i = 0; i < num_freqs; i++) {
+		hash_for_each_possible(freq_hash_table, freq_entry, hash,
+				freq_buckets[i]) {
+			if (freq_entry->freq == freq_buckets[i]) {
+				len += scnprintf(buf + len, PAGE_SIZE - len,
+						"%d ", freq_buckets[i]);
+				if (len >= PAGE_SIZE)
+					break;
+				for (j = 0; j < num_buckets; j++) {
+					len += scnprintf(buf + len,
+							PAGE_SIZE - len,
+							"%llu ",
+							freq_entry->buckets[j]);
+				}
+				len += scnprintf(buf + len, PAGE_SIZE - len,
+						"\n");
+			}
+		}
+	}
+	pr_debug("Current Time: %llu\n", ktime_get_boot_ns());
+	return len;
+}
+KERNEL_ATTR_RO(show_stat);
+
+static void update_table(u64 time_now)
+{
+	struct freq_entry *freq_entry;
+
+	pr_debug("Last known bw %d freq %d\n", curr_bw, curr_freq);
+	hash_for_each_possible(freq_hash_table, freq_entry, hash, curr_freq) {
+		if (curr_freq == freq_entry->freq) {
+			freq_entry->buckets[find_bucket(curr_bw)]
+					+= get_time_diff(time_now);
+			break;
+		}
+	}
+}
+
+static bool freq_exists(int freq)
+{
+	int i;
+
+	for (i = 0; i < num_freqs; i++) {
+		if (freq == freq_buckets[i])
+			return true;
+	}
+	return false;
+}
+
+static int calculate_total_bw(int bw, int index)
+{
+	int i;
+	int total_bw = 0;
+
+	pr_debug("memory_state_time New bw %d for id %d\n", bw, index);
+	bandwidths[index] = bw;
+	for (i = 0; i < registered_bw_sources; i++)
+		total_bw += bandwidths[i];
+	return total_bw;
+}
+
+static void freq_update_do_work(struct work_struct *work)
+{
+	struct queue_container *freq_state_update
+			= container_of(work, struct queue_container,
+			update_state);
+	if (freq_state_update) {
+		mutex_lock(&mem_lock);
+		update_table(freq_state_update->time_now);
+		curr_freq = freq_state_update->value;
+		mutex_unlock(&mem_lock);
+		kfree(freq_state_update);
+	}
+}
+
+static void bw_update_do_work(struct work_struct *work)
+{
+	struct queue_container *bw_state_update
+			= container_of(work, struct queue_container,
+			update_state);
+	if (bw_state_update) {
+		mutex_lock(&mem_lock);
+		update_table(bw_state_update->time_now);
+		curr_bw = calculate_total_bw(bw_state_update->value,
+				bw_state_update->id);
+		mutex_unlock(&mem_lock);
+		kfree(bw_state_update);
+	}
+}
+
+static void memory_state_freq_update(struct memory_state_update_block *ub,
+		int value)
+{
+	if (IS_ENABLED(CONFIG_MEMORY_STATE_TIME)) {
+		if (freq_exists(value) && init_success) {
+			struct queue_container *freq_container
+				= kmalloc(sizeof(struct queue_container),
+				GFP_KERNEL);
+			if (!freq_container)
+				return;
+			INIT_WORK(&freq_container->update_state,
+					freq_update_do_work);
+			freq_container->time_now = ktime_get_boot_ns();
+			freq_container->value = value;
+			pr_debug("Scheduling freq update in work queue\n");
+			queue_work(memory_wq, &freq_container->update_state);
+		} else {
+			pr_debug("Freq does not exist.\n");
+		}
+	}
+}
+
+static void memory_state_bw_update(struct memory_state_update_block *ub,
+		int value)
+{
+	if (IS_ENABLED(CONFIG_MEMORY_STATE_TIME)) {
+		if (init_success) {
+			struct queue_container *bw_container
+				= kmalloc(sizeof(struct queue_container),
+				GFP_KERNEL);
+			if (!bw_container)
+				return;
+			INIT_WORK(&bw_container->update_state,
+					bw_update_do_work);
+			bw_container->time_now = ktime_get_boot_ns();
+			bw_container->value = value;
+			bw_container->id = ub->id;
+			pr_debug("Scheduling bandwidth update in work queue\n");
+			queue_work(memory_wq, &bw_container->update_state);
+		}
+	}
+}
+
+struct memory_state_update_block *memory_state_register_frequency_source(void)
+{
+	struct memory_state_update_block *block;
+
+	if (IS_ENABLED(CONFIG_MEMORY_STATE_TIME)) {
+		pr_debug("Allocating frequency source\n");
+		block = kmalloc(sizeof(struct memory_state_update_block),
+					GFP_KERNEL);
+		if (!block)
+			return NULL;
+		block->update_call = memory_state_freq_update;
+		return block;
+	}
+	pr_err("Config option disabled.\n");
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(memory_state_register_frequency_source);
+
+struct memory_state_update_block *memory_state_register_bandwidth_source(void)
+{
+	struct memory_state_update_block *block;
+
+	if (IS_ENABLED(CONFIG_MEMORY_STATE_TIME)) {
+		pr_debug("Allocating bandwidth source %d\n",
+				registered_bw_sources);
+		block = kmalloc(sizeof(struct memory_state_update_block),
+					GFP_KERNEL);
+		if (!block)
+			return NULL;
+		block->update_call = memory_state_bw_update;
+		if (registered_bw_sources < num_sources) {
+			block->id = registered_bw_sources++;
+		} else {
+			pr_err("Unable to allocate source; max number reached\n");
+			kfree(block);
+			return NULL;
+		}
+		return block;
+	}
+	pr_err("Config option disabled.\n");
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(memory_state_register_bandwidth_source);
+
+/* Buckets are designated by their maximum.
+ * Returns the buckets decided by the capability of the device.
+ */
+static int get_bw_buckets(struct device *dev)
+{
+	int ret, lenb;
+	struct device_node *node = dev->of_node;
+
+	of_property_read_u32(node, NUM_SOURCES, &num_sources);
+	if (of_find_property(node, BW_TBL, &lenb)) {
+		bandwidths = devm_kzalloc(dev,
+				sizeof(*bandwidths) * num_sources, GFP_KERNEL);
+		if (!bandwidths)
+			return -ENOMEM;
+		lenb /= sizeof(*bw_buckets);
+		bw_buckets = devm_kzalloc(dev, lenb * sizeof(*bw_buckets),
+				GFP_KERNEL);
+		if (!bw_buckets) {
+			devm_kfree(dev, bandwidths);
+			return -ENOMEM;
+		}
+		ret = of_property_read_u32_array(node, BW_TBL, bw_buckets,
+				lenb);
+		if (ret < 0) {
+			devm_kfree(dev, bandwidths);
+			devm_kfree(dev, bw_buckets);
+			pr_err("Unable to read bandwidth table from device tree.\n");
+			return ret;
+		}
+	}
+	curr_bw = 0;
+	num_buckets = lenb;
+	return 0;
+}
+
+/* Adds struct freq_entry nodes to the hashtable for each compatible frequency.
+ * Returns the supported number of frequencies.
+ */
+static int freq_buckets_init(struct device *dev)
+{
+	struct freq_entry *freq_entry;
+	int i;
+	int ret, lenf;
+	struct device_node *node = dev->of_node;
+
+	if (of_find_property(node, FREQ_TBL, &lenf)) {
+		lenf /= sizeof(*freq_buckets);
+		freq_buckets = devm_kzalloc(dev, lenf * sizeof(*freq_buckets),
+				GFP_KERNEL);
+		if (!freq_buckets)
+			return -ENOMEM;
+		pr_debug("freqs found len %d\n", lenf);
+		ret = of_property_read_u32_array(node, FREQ_TBL, freq_buckets,
+				lenf);
+		if (ret < 0) {
+			devm_kfree(dev, freq_buckets);
+			pr_err("Unable to read frequency table from device tree.\n");
+			return ret;
+		}
+		pr_debug("ret freq %d\n", ret);
+	}
+	num_freqs = lenf;
+	curr_freq = freq_buckets[LOWEST_FREQ];
+
+	for (i = 0; i < num_freqs; i++) {
+		freq_entry = devm_kzalloc(dev, sizeof(struct freq_entry),
+				GFP_KERNEL);
+		if (!freq_entry)
+			return -ENOMEM;
+		freq_entry->buckets = devm_kzalloc(dev, sizeof(u64)*num_buckets,
+				GFP_KERNEL);
+		if (!freq_entry->buckets) {
+			devm_kfree(dev, freq_entry);
+			return -ENOMEM;
+		}
+		pr_debug("memory_state_time Adding freq to ht %d\n",
+				freq_buckets[i]);
+		freq_entry->freq = freq_buckets[i];
+		hash_add(freq_hash_table, &freq_entry->hash, freq_buckets[i]);
+	}
+	return 0;
+}
+
+struct kobject *memory_kobj;
+EXPORT_SYMBOL_GPL(memory_kobj);
+
+static struct attribute *memory_attrs[] = {
+	&show_stat_attr.attr,
+	NULL
+};
+
+static struct attribute_group memory_attr_group = {
+	.attrs = memory_attrs,
+};
+
+static int memory_state_time_probe(struct platform_device *pdev)
+{
+	int error;
+
+	error = get_bw_buckets(&pdev->dev);
+	if (error)
+		return error;
+	error = freq_buckets_init(&pdev->dev);
+	if (error)
+		return error;
+	last_update = ktime_get_boot_ns();
+	init_success = true;
+
+	pr_debug("memory_state_time initialized with num_freqs %d\n",
+			num_freqs);
+	return 0;
+}
+
+static const struct of_device_id match_table[] = {
+	{ .compatible = "memory-state-time" },
+	{}
+};
+
+static struct platform_driver memory_state_time_driver = {
+	.probe = memory_state_time_probe,
+	.driver = {
+		.name = "memory-state-time",
+		.of_match_table = match_table,
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init memory_state_time_init(void)
+{
+	int error;
+
+	hash_init(freq_hash_table);
+	memory_wq = create_singlethread_workqueue("memory_wq");
+	if (!memory_wq) {
+		pr_err("Unable to create workqueue.\n");
+		return -EINVAL;
+	}
+	/*
+	 * Create sys/kernel directory for memory_state_time.
+	 */
+	memory_kobj = kobject_create_and_add(TAG, kernel_kobj);
+	if (!memory_kobj) {
+		pr_err("Unable to allocate memory_kobj for sysfs directory.\n");
+		error = -ENOMEM;
+		goto wq;
+	}
+	error = sysfs_create_group(memory_kobj, &memory_attr_group);
+	if (error) {
+		pr_err("Unable to create sysfs folder.\n");
+		goto kobj;
+	}
+
+	error = platform_driver_register(&memory_state_time_driver);
+	if (error) {
+		pr_err("Unable to register memory_state_time platform driver.\n");
+		goto group;
+	}
+	return 0;
+
+group:	sysfs_remove_group(memory_kobj, &memory_attr_group);
+kobj:	kobject_put(memory_kobj);
+wq:	destroy_workqueue(memory_wq);
+	return error;
+}
+module_init(memory_state_time_init);