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>

1 files changed, 42 insertions, 0 deletions

diff --git a/include/linux/memory-state-time.h b/include/linux/memory-state-time.h
new file mode 100644
index 000000000000..d2212b027866
--- /dev/null
+++ b/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);