ANDROID: Implement memory_state_time, used by qcom,cpubw

New driver memory_state_time tracks time spent in different DDR
frequency and bandwidth states.

Memory drivers such as qcom,cpubw can post updated state to the driver
after registering a callback. Processed by a workqueue

Bandwidth buckets are read in from device tree in the relevant qualcomm
section, can be defined in any quantity and spacing.

The data is exposed at /sys/kernel/memory_state_time, able to be read by
the Android framework.

Functionality is behind a config option CONFIG_MEMORY_STATE_TIME

Change-Id: I4fee165571cb975fb9eacbc9aada5e6d7dd748f0
Signed-off-by: James Carr <carrja@google.com>

Documentation/devicetree/bindings/misc/memory-state-time.txt

@@ -0,0 +1,8 @@
+Memory bandwidth and frequency state tracking
+
+Required properties:
+- compatible : should be:
+       "memory-state-time"
+- freq-tbl: Should contain entries with each frequency in Hz.
+- bw-buckets: Should contain upper-bound limits for each bandwidth bucket in Mbps.
+       Must match the framework power_profile.xml for the device.

drivers/misc/Kconfig

@@ -772,6 +772,12 @@ config UID_CPUTIME
 	help
 	  Per UID based cpu time statistics exported to /proc/uid_cputime
 
+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"
 source "drivers/misc/cb710/Kconfig"

drivers/misc/Makefile

@@ -55,6 +55,7 @@ obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_PANEL)             += panel.o
 
 obj-$(CONFIG_UID_CPUTIME)	+= uid_cputime.o
+obj-$(CONFIG_MEMORY_STATE_TIME)	+= memory_state_time.o
 
 lkdtm-$(CONFIG_LKDTM)		+= lkdtm_core.o
 lkdtm-$(CONFIG_LKDTM)		+= lkdtm_bugs.o

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);

include/linux/memory-state-time.h

@@ -0,0 +1,42 @@
+/* include/linux/memory-state-time.h
+ *
+ * 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/workqueue.h>
+
+#define UPDATE_MEMORY_STATE(BLOCK, VALUE) BLOCK->update_call(BLOCK, VALUE)
+
+struct memory_state_update_block;
+
+typedef void (*memory_state_update_fn_t)(struct memory_state_update_block *ub,
+		int value);
+
+/* This struct is populated when you pass it to a memory_state_register*
+ * function. The update_call function is used for an update and defined in the
+ * typedef memory_state_update_fn_t
+ */
+struct memory_state_update_block {
+	memory_state_update_fn_t update_call;
+	int id;
+};
+
+/* Register a frequency struct memory_state_update_block to provide updates to
+ * memory_state_time about frequency changes using its update_call function.
+ */
+struct memory_state_update_block *memory_state_register_frequency_source(void);
+
+/* Register a bandwidth struct memory_state_update_block to provide updates to
+ * memory_state_time about bandwidth changes using its update_call function.
+ */
+struct memory_state_update_block *memory_state_register_bandwidth_source(void);