Commit 18fc64dc authored by Jithu Joseph's avatar Jithu Joseph Committed by Anas Nashif
Browse files

power_mgmt: Sample usage of device_xxx__busy() APIs 



To show possible usage of the device_busy_xxx() APIs.
Meant to show how drivers and power policy manager can use them.

Change-Id: I49d1dedd9a7b8d6bf09080c6c7243f0666330941
Signed-off-by: default avatarJithu Joseph <jithu.joseph@intel.com>
parent 592882e5

drivers/i2c/i2c_dw.c

+16 −0
Original line number Diff line number Diff line
@@ -459,6 +459,20 @@ static int i2c_dw_transfer(struct device *dev, 
	/* Enable controller */

	regs->ic_enable.bits.enable = 1;



	/*

	 * While waiting at device_sync_call_wait(), kernel can switch to idle

	 * task which in turn can call _sys_soc_suspend() hook of Power

	 * Management App (PMA).

	 * device_busy_set() call here, would indicate to PMA that it should not

	 * execute PM policies that would turn off this ip block, causing an

	 * ongoing hw transaction to be left in an inconsistent state.

	 * Note : This is just a sample to show a possible use of the API, it is

	 * upto the driver expert to see, if he actually needs it here, or

	 * somewhere else, or not needed as the driver's suspend()/resume()

	 * can handle everything

	 */

	device_busy_set(dev);



		/* Process all the messages */

	while (msg_left > 0) {

		pflags = dw->xfr_flags;
@@ -517,6 +531,8 @@ static int i2c_dw_transfer(struct device *dev, 
		msg_left--;

	}



	device_busy_clear(dev);



	dw->state = I2C_DW_STATE_READY;



	return ret;

samples/power/power_mgr/prj.conf

+1 −0
Original line number Diff line number Diff line
@@ -5,3 +5,4 @@ CONFIG_TICKLESS_IDLE=y 
CONFIG_RTC=y

CONFIG_GPIO=y

CONFIG_STDOUT_CONSOLE=y

CONFIG_I2C=y
 
 No newline at end of file

samples/power/power_mgr/src/main.c

+15 −1
Original line number Diff line number Diff line
@@ -79,9 +79,10 @@ static int check_pm_policy(int32_t ticks) 
	 * 0 = no power saving operation

	 * 1 = low power state

	 * 2 = device suspend only

	 * 3 = deep sleep

	 *

	 */

	policy = (policy > 2 ? 0 : policy);

	policy = (policy > 3 ? 0 : policy);



	return policy++;

}
@@ -123,6 +124,15 @@ int _sys_soc_suspend(int32_t ticks) 
		start_time = rtc_read(rtc_dev);

		ret = device_suspend_only_entry(ticks);

		break;

	case 3:

		/*

		 * if the policy manager chooses to go to deep sleep, we need to

		 * check if any device is in the middle of a transaction

		 */

		if (!device_any_busy_check()) {

			/* Do deep sleep operations */

			/* break; (fall through for now) */

		}

	default:

		/* No PM operations */

		ret = SYS_PM_NOT_HANDLED;
@@ -190,6 +200,10 @@ static void suspend_devices(int pm_policy) 
	for (i = 0; i < device_count; i++) {

		int idx = device_policy_list[i];



		/* If necessary  the policy manager can check if a specific

		 * device in the policy list is busy as shown below :

		 * if(device_busy_check(&device_list[idx])) {do something}

		 */

		device_retval[i] = device_suspend(&device_list[idx], pm_policy);

	}

}

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