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: Roger Quadros <rogerq@ti.com> Acked-by: Peter Chen <peter.chen@freescale.com> Signed-off-by: Peter Chen <peter.chen@nxp.com>
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Roger Quadros
Peter Chen
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2b2fe36def
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fa59507f72
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@ -72,37 +72,113 @@ enum otg_fsm_timer {
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NUM_OTG_FSM_TIMERS,
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};
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/* OTG state machine according to the OTG spec */
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/**
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* struct otg_fsm - OTG state machine according to the OTG spec
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*
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* OTG hardware Inputs
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*
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* Common inputs for A and B device
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* @id: TRUE for B-device, FALSE for A-device.
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* @adp_change: TRUE when current ADP measurement (n) value, compared to the
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* ADP measurement taken at n-2, differs by more than CADP_THR
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* @power_up: TRUE when the OTG device first powers up its USB system and
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* ADP measurement taken if ADP capable
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*
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* A-Device state inputs
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* @a_srp_det: TRUE if the A-device detects SRP
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* @a_vbus_vld: TRUE when VBUS voltage is in regulation
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* @b_conn: TRUE if the A-device detects connection from the B-device
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* @a_bus_resume: TRUE when the B-device detects that the A-device is signaling
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* a resume (K state)
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* B-Device state inputs
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* @a_bus_suspend: TRUE when the B-device detects that the A-device has put the
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* bus into suspend
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* @a_conn: TRUE if the B-device detects a connection from the A-device
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* @b_se0_srp: TRUE when the line has been at SE0 for more than the minimum
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* time before generating SRP
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* @b_ssend_srp: TRUE when the VBUS has been below VOTG_SESS_VLD for more than
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* the minimum time before generating SRP
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* @b_sess_vld: TRUE when the B-device detects that the voltage on VBUS is
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* above VOTG_SESS_VLD
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* @test_device: TRUE when the B-device switches to B-Host and detects an OTG
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* test device. This must be set by host/hub driver
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*
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* Application inputs (A-Device)
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* @a_bus_drop: TRUE when A-device application needs to power down the bus
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* @a_bus_req: TRUE when A-device application wants to use the bus.
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* FALSE to suspend the bus
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*
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* Application inputs (B-Device)
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* @b_bus_req: TRUE during the time that the Application running on the
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* B-device wants to use the bus
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*
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* Auxilary inputs (OTG v1.3 only. Obsolete now.)
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* @a_sess_vld: TRUE if the A-device detects that VBUS is above VA_SESS_VLD
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* @b_bus_suspend: TRUE when the A-device detects that the B-device has put
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* the bus into suspend
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* @b_bus_resume: TRUE when the A-device detects that the B-device is signaling
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* resume on the bus
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*
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* OTG Output status. Read only for users. Updated by OTG FSM helpers defined
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* in this file
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*
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* Outputs for Both A and B device
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* @drv_vbus: TRUE when A-device is driving VBUS
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* @loc_conn: TRUE when the local device has signaled that it is connected
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* to the bus
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* @loc_sof: TRUE when the local device is generating activity on the bus
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* @adp_prb: TRUE when the local device is in the process of doing
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* ADP probing
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*
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* Outputs for B-device state
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* @adp_sns: TRUE when the B-device is in the process of carrying out
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* ADP sensing
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* @data_pulse: TRUE when the B-device is performing data line pulsing
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*
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* Internal Variables
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*
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* a_set_b_hnp_en: TRUE when the A-device has successfully set the
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* b_hnp_enable bit in the B-device.
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* Unused as OTG fsm uses otg->host->b_hnp_enable instead
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* b_srp_done: TRUE when the B-device has completed initiating SRP
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* b_hnp_enable: TRUE when the B-device has accepted the
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* SetFeature(b_hnp_enable) B-device.
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* Unused as OTG fsm uses otg->gadget->b_hnp_enable instead
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* a_clr_err: Asserted (by application ?) to clear a_vbus_err due to an
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* overcurrent condition and causes the A-device to transition
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* to a_wait_vfall
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*/
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struct otg_fsm {
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/* Input */
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int id;
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int adp_change;
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int power_up;
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int test_device;
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int a_bus_drop;
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int a_bus_req;
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int a_srp_det;
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int a_vbus_vld;
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int b_conn;
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int a_bus_resume;
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int a_bus_suspend;
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int a_conn;
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int b_bus_req;
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int b_se0_srp;
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int b_ssend_srp;
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int b_sess_vld;
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int test_device;
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int a_bus_drop;
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int a_bus_req;
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int b_bus_req;
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/* Auxilary inputs */
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int a_sess_vld;
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int b_bus_resume;
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int b_bus_suspend;
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/* Output */
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int data_pulse;
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int drv_vbus;
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int loc_conn;
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int loc_sof;
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int adp_prb;
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int adp_sns;
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int data_pulse;
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/* Internal variables */
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int a_set_b_hnp_en;
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@ -110,7 +186,7 @@ struct otg_fsm {
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int b_hnp_enable;
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int a_clr_err;
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/* Informative variables */
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/* Informative variables. All unused as of now */
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int a_bus_drop_inf;
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int a_bus_req_inf;
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int a_clr_err_inf;
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