From fa59507f720077a856c9952a31cfd45cd97ef6f9 Mon Sep 17 00:00:00 2001 From: Roger Quadros Date: Wed, 30 Mar 2016 12:56:28 +0300 Subject: [PATCH] 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 Acked-by: Peter Chen Signed-off-by: Peter Chen --- include/linux/usb/otg-fsm.h | 90 ++++++++++++++++++++++++++++++++++--- 1 file changed, 83 insertions(+), 7 deletions(-) diff --git a/include/linux/usb/otg-fsm.h b/include/linux/usb/otg-fsm.h index 24198e16f849..8eec0c261be5 100644 --- a/include/linux/usb/otg-fsm.h +++ b/include/linux/usb/otg-fsm.h @@ -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;