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Commit fa59507f authored by Roger Quadros's avatar Roger Quadros Committed by Peter Chen
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usb: otg-fsm: Add documentation for struct otg_fsm 



struct otg_fsm is the interface to the OTG state machine.

Document the input, output and internal state variables.
Definations are taken from Table 7-2 and Table 7-4 of
the USB OTG & EH Specification Rev.2.0

Re-arrange some of the members as per use case for more
clarity.

Signed-off-by: default avatarRoger Quadros <rogerq@ti.com>
Acked-by: default avatarPeter Chen <peter.chen@freescale.com>
Signed-off-by: default avatarPeter Chen <peter.chen@nxp.com>
parent 2b2fe36d

include/linux/usb/otg-fsm.h

+83 −7
Original line number Diff line number Diff line
@@ -72,37 +72,113 @@ enum otg_fsm_timer { 
	NUM_OTG_FSM_TIMERS,

};



/* OTG state machine according to the OTG spec */

/**

 * struct otg_fsm - OTG state machine according to the OTG spec

 *

 * OTG hardware Inputs

 *

 *	Common inputs for A and B device

 * @id:		TRUE for B-device, FALSE for A-device.

 * @adp_change: TRUE when current ADP measurement (n) value, compared to the

 *		ADP measurement taken at n-2, differs by more than CADP_THR

 * @power_up:	TRUE when the OTG device first powers up its USB system and

 *		ADP measurement taken if ADP capable

 *

 *	A-Device state inputs

 * @a_srp_det:	TRUE if the A-device detects SRP

 * @a_vbus_vld:	TRUE when VBUS voltage is in regulation

 * @b_conn:	TRUE if the A-device detects connection from the B-device

 * @a_bus_resume: TRUE when the B-device detects that the A-device is signaling

 *		  a resume (K state)

 *	B-Device state inputs

 * @a_bus_suspend: TRUE when the B-device detects that the A-device has put the

 *		bus into suspend

 * @a_conn:	TRUE if the B-device detects a connection from the A-device

 * @b_se0_srp:	TRUE when the line has been at SE0 for more than the minimum

 *		time before generating SRP

 * @b_ssend_srp: TRUE when the VBUS has been below VOTG_SESS_VLD for more than

 *		 the minimum time before generating SRP

 * @b_sess_vld:	TRUE when the B-device detects that the voltage on VBUS is

 *		above VOTG_SESS_VLD

 * @test_device: TRUE when the B-device switches to B-Host and detects an OTG

 *		test device. This must be set by host/hub driver

 *

 *	Application inputs (A-Device)

 * @a_bus_drop:	TRUE when A-device application needs to power down the bus

 * @a_bus_req:	TRUE when A-device application wants to use the bus.

 *		FALSE to suspend the bus

 *

 *	Application inputs (B-Device)

 * @b_bus_req:	TRUE during the time that the Application running on the

 *		B-device wants to use the bus

 *

 *	Auxilary inputs (OTG v1.3 only. Obsolete now.)

 * @a_sess_vld:	TRUE if the A-device detects that VBUS is above VA_SESS_VLD

 * @b_bus_suspend: TRUE when the A-device detects that the B-device has put

 *		the bus into suspend

 * @b_bus_resume: TRUE when the A-device detects that the B-device is signaling

 *		 resume on the bus

 *

 * OTG Output status. Read only for users. Updated by OTG FSM helpers defined

 * in this file

 *

 *	Outputs for Both A and B device

 * @drv_vbus:	TRUE when A-device is driving VBUS

 * @loc_conn:	TRUE when the local device has signaled that it is connected

 *		to the bus

 * @loc_sof:	TRUE when the local device is generating activity on the bus

 * @adp_prb:	TRUE when the local device is in the process of doing

 *		ADP probing

 *

 *	Outputs for B-device state

 * @adp_sns:	TRUE when the B-device is in the process of carrying out

 *		ADP sensing

 * @data_pulse: TRUE when the B-device is performing data line pulsing

 *

 * Internal Variables

 *

 * a_set_b_hnp_en: TRUE when the A-device has successfully set the

 *		b_hnp_enable bit in the B-device.

 *		   Unused as OTG fsm uses otg->host->b_hnp_enable instead

 * b_srp_done:	TRUE when the B-device has completed initiating SRP

 * b_hnp_enable: TRUE when the B-device has accepted the

 *		SetFeature(b_hnp_enable) B-device.

 *		Unused as OTG fsm uses otg->gadget->b_hnp_enable instead

 * a_clr_err:	Asserted (by application ?) to clear a_vbus_err due to an

 *		overcurrent condition and causes the A-device to transition

 *		to a_wait_vfall

 */

struct otg_fsm {

	/* Input */

	int id;

	int adp_change;

	int power_up;

	int test_device;

	int a_bus_drop;

	int a_bus_req;

	int a_srp_det;

	int a_vbus_vld;

	int b_conn;

	int a_bus_resume;

	int a_bus_suspend;

	int a_conn;

	int b_bus_req;

	int b_se0_srp;

	int b_ssend_srp;

	int b_sess_vld;

	int test_device;

	int a_bus_drop;

	int a_bus_req;

	int b_bus_req;



	/* Auxilary inputs */

	int a_sess_vld;

	int b_bus_resume;

	int b_bus_suspend;



	/* Output */

	int data_pulse;

	int drv_vbus;

	int loc_conn;

	int loc_sof;

	int adp_prb;

	int adp_sns;

	int data_pulse;



	/* Internal variables */

	int a_set_b_hnp_en;
@@ -110,7 +186,7 @@ struct otg_fsm { 
	int b_hnp_enable;

	int a_clr_err;



	/* Informative variables */

	/* Informative variables. All unused as of now */

	int a_bus_drop_inf;

	int a_bus_req_inf;

	int a_clr_err_inf;