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power_mgmt: APIs for devices to signal busy

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Certain Low power SOC states (e.g. deep sleep)  will result in device
IP blocks losing state. In such a scenario it can be useful to have
a mechanism for devices (driver code) to signal the power manager /
policy that they are in the middle of a transaction.

We expect the device driver code to make a call to
device_busy_set(device *) before initiating a transaction and
device_busy_clear(device *) on completion. It is expected that device
driver developers will add this as necessary in their drivers.

Further an API is provided  for power manager application / policy to
check this. Based on this the power manager / policy can  decide
whether or not to go into a particular power state.

Change-Id: I0fedd90b98e182cd41b53c7f9e08655532822faa
Signed-off-by: Jithu Joseph <jithu.joseph@intel.com>
This commit is contained in:
Jithu Joseph 2016-04-08 12:38:57 -07:00 • committed by Anas Nashif
commit 592882e5f4
4 changed files with 110 additions and 1 deletions
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21
include/linker-defs.h
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@ -45,6 +45,24 @@
#ifdef _LINKER
/*
* Space for storing per device busy bitmap. Since we do not know beforehand
* the number of devices, we go through the below mechanism to allocate the
* required space.
*/
#ifdef CONFIG_DEVICE_POWER_MANAGEMENT
#define DEVICE_COUNT ((__device_init_end - __device_init_start) / __DEVICE_STR_SIZEOF)
#define DEV_BUSY_SZ (((DEVICE_COUNT + 31) / 32) * 4)
#define DEVICE_BUSY_BITFIELD() \
FILL(0x00) ; \
__device_busy_start = .; \
. = . + DEV_BUSY_SZ; \
__device_busy_end = .;
#else
#define DEVICE_BUSY_BITFIELD()
#endif
/*
* generate a symbol to mark the start of the device initialization objects for
* the specified level, then link all of those objects (sorted by priority);
@ -69,7 +87,8 @@
DEVICE_INIT_LEVEL(NANOKERNEL) \
DEVICE_INIT_LEVEL(MICROKERNEL) \
DEVICE_INIT_LEVEL(APPLICATION) \
__device_init_end = .; \
__device_init_end = .; \
DEVICE_BUSY_BITFIELD() \
/* define a section for undefined device initialization levels */