Commit 592882e5 authored by Jithu Joseph's avatar Jithu Joseph Committed by Anas Nashif
Browse files

power_mgmt: APIs for devices to signal busy 



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: default avatarJithu Joseph <jithu.joseph@intel.com>
parent 35360df9

include/device.h

+43 −0
Original line number Diff line number Diff line
@@ -304,6 +304,25 @@ struct device { 
void _sys_device_do_config_level(int level);

struct device* device_get_binding(char *name);



/**

 * @brief Indicate that the device is in the middle of a transaction

 *

 * Called by a device driver to indicate that it is in the middle of a

 * transaction.

 *

 * @param busy_dev Pointer to device structure of the driver instance.

 */

void device_busy_set(struct device *busy_dev);



/**

 * @brief Indicate that the device has completed its transaction

 *

 * Called by a device driver to indicate the end of a transaction.

 *

 * @param busy_dev Pointer to device structure of the driver instance.

 */

void device_busy_clear(struct device *busy_dev);



#ifdef CONFIG_DEVICE_POWER_MANAGEMENT

/**

 * Device PM functions
@@ -370,6 +389,30 @@ static inline int device_resume(struct device *device, int pm_policy) 
 */

void device_list_get(struct device **device_list, int *device_count);



/**

 * @brief Check if any device is in the middle of a transaction

 *

 * Called by an application to see if any device is in the middle

 * of a critical transaction that cannot be interrupted.

 *

 * @retval 0 if no device is busy

 * @retval -EBUSY if any device is busy

 */

int device_any_busy_check(void);



/**

 * @brief Check if a specific device is in the middle of a transaction

 *

 * Called by an application to see if a particular device is in the

 * middle of a critical transaction that cannot be interrupted.

 *

 * @param chk_dev Pointer to device structure of the specific device driver

 * the caller is interested in.

 * @retval 0 if the device is not busy

 * @retval -EBUSY if the device is busy

 */

int device_busy_check(struct device *chk_dev);



#endif



/**

include/linker-defs.h

+20 −1
Original line number Diff line number Diff line
@@ -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);
@@ -70,6 +88,7 @@ 
		DEVICE_INIT_LEVEL(MICROKERNEL)	\

		DEVICE_INIT_LEVEL(APPLICATION)	\

		__device_init_end = .;		\

		DEVICE_BUSY_BITFIELD()		\





/* define a section for undefined device initialization levels */

kernel/nanokernel/device.c

+43 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <string.h>

#include <device.h>

#include <misc/util.h>

#include <atomic.h>



extern struct device __device_init_start[];

extern struct device __device_PRIMARY_start[];
@@ -37,6 +38,9 @@ static struct device *config_levels[] = { 


#ifdef CONFIG_DEVICE_POWER_MANAGEMENT

struct device_pm_ops device_pm_ops_nop = {device_pm_nop, device_pm_nop};

extern uint32_t __device_busy_start[];

extern uint32_t __device_busy_end[];

#define DEVICE_BUSY_SIZE (__device_busy_end - __device_busy_start)

#endif



/**
@@ -98,4 +102,43 @@ void device_list_get(struct device **device_list, int *device_count) 
	*device_list = __device_init_start;

	*device_count = __device_init_end - __device_init_start;

}





int device_any_busy_check(void)

{

	int i = 0;



	for (i = 0; i < DEVICE_BUSY_SIZE; i++) {

		if (__device_busy_start[i] != 0) {

			return -EBUSY;

		}

	}

	return 0;

}



int device_busy_check(struct device *chk_dev)

{

	if (atomic_test_bit((const atomic_t *)__device_busy_start,

				 (chk_dev - __device_init_start))) {

		return -EBUSY;

	}

	return 0;

}



#endif



void device_busy_set(struct device *busy_dev)

{

#ifdef CONFIG_DEVICE_POWER_MANAGEMENT

	atomic_set_bit((atomic_t *) __device_busy_start,

				 (busy_dev - __device_init_start));

#endif

}



void device_busy_clear(struct device *busy_dev)

{

#ifdef CONFIG_DEVICE_POWER_MANAGEMENT

	atomic_clear_bit((atomic_t *) __device_busy_start,

				 (busy_dev - __device_init_start));

#endif

}

kernel/nanokernel/include/nano_offsets.h

+4 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <device.h>



#ifndef _NANO_OFFSETS__H_

#define _NANO_OFFSETS__H_
@@ -64,4 +65,7 @@ GEN_OFFSET_SYM(tTCS, errno_var); 


GEN_ABSOLUTE_SYM(__tTCS_SIZEOF, sizeof(tTCS));



/* size of the device structure. Used by linker scripts */

GEN_ABSOLUTE_SYM(__DEVICE_STR_SIZEOF, sizeof(struct device));



#endif /* _NANO_OFFSETS__H_ */

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