Re: [RFC][PATCH 3/9] usb: otg: add OTG core

[Peter Chen]

On Thu, Mar 19, 2015 at 12:18:55PM +0200, Roger Quadros wrote:
> On 19/03/15 05:40, Peter Chen wrote:
> > On Wed, Mar 18, 2015 at 03:55:57PM +0200, Roger Quadros wrote:
> >> The OTG core instantiates the OTG Finite State Machine
> >> per OTG controller and manages starting/stopping the
> >> host and gadget controllers based on the bus state.
> >>
> >> It provides APIs for the following tasks
> >>
> >> - Registering an OTG capable controller
> >> - Registering Host and Gadget controllers to OTG core
> >> - Providing inputs to and kicking the OTG state machine
> >>
> >> TODO:
> >> - sysfs interface to allow application inputs to OTG state machine
> >> - otg class?
> >>
> >> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> >> ---
> >>  drivers/usb/Makefile         |   1 +
> >>  drivers/usb/common/Makefile  |   1 +
> >>  drivers/usb/common/usb-otg.c | 732 +++++++++++++++++++++++++++++++++++++++++++
> >>  drivers/usb/common/usb-otg.h |  71 +++++
> >>  drivers/usb/core/Kconfig     |   8 +
> >>  include/linux/usb/usb-otg.h  |  86 +++++
> >>  6 files changed, 899 insertions(+)
> >>  create mode 100644 drivers/usb/common/usb-otg.c
> >>  create mode 100644 drivers/usb/common/usb-otg.h
> >>  create mode 100644 include/linux/usb/usb-otg.h
> >>
> >> diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
> >> index 2f1e2aa..07f59a5 100644
> >> --- a/drivers/usb/Makefile
> >> +++ b/drivers/usb/Makefile
> >> @@ -60,5 +60,6 @@ obj-$(CONFIG_USB_RENESAS_USBHS)	+= renesas_usbhs/
> >>  obj-$(CONFIG_USB_GADGET)	+= gadget/
> >>  
> >>  obj-$(CONFIG_USB_COMMON)	+= common/
> >> +obj-$(CONFIG_USB_OTG_CORE)	+= common/
> >>  
> >>  obj-$(CONFIG_USBIP_CORE)	+= usbip/
> >> diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
> >> index ca2f8bd..573fc75 100644
> >> --- a/drivers/usb/common/Makefile
> >> +++ b/drivers/usb/common/Makefile
> >> @@ -7,3 +7,4 @@ usb-common-y			  += common.o
> >>  usb-common-$(CONFIG_USB_LED_TRIG) += led.o
> >>  
> >>  obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
> >> +obj-$(CONFIG_USB_OTG_CORE) += usb-otg.o
> >> diff --git a/drivers/usb/common/usb-otg.c b/drivers/usb/common/usb-otg.c
> >> new file mode 100644
> >> index 0000000..1433fc9
> >> --- /dev/null
> >> +++ b/drivers/usb/common/usb-otg.c
> >> @@ -0,0 +1,732 @@
> >> +/**
> >> + * drivers/usb/common/usb-otg.c - USB OTG core
> >> + *
> >> + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
> >> + * Author: Roger Quadros <rogerq@xxxxxx>
> >> + *
> >> + * This program is free software; you can redistribute it and/or modify
> >> + * it under the terms of the GNU General Public License version 2 as
> >> + * published by the Free Software Foundation.
> >> + *
> >> + * This program is distributed in the hope that it will be useful,
> >> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> >> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> >> + * GNU General Public License for more details.
> >> + */
> >> +
> >> +#include <linux/kernel.h>
> >> +#include <linux/list.h>
> >> +#include <linux/timer.h>
> >> +#include <linux/usb/otg.h>
> >> +#include <linux/usb/phy.h>	/* enum usb_otg_state */
> >> +#include <linux/usb/gadget.h>
> >> +#include <linux/usb/usb-otg.h>
> >> +#include <linux/workqueue.h>
> >> +
> >> +#include "usb-otg.h"
> >> +
> >> +/* to link timer with callback data */
> >> +struct otg_timer {
> >> +	struct timer_list timer;
> >> +	/* callback data */
> >> +	int *timeout_bit;
> >> +	struct otg_data *otgd;
> >> +};
> >> +
> >> +struct otg_data {
> >> +	struct device *dev;	/* HCD & GCD's parent device */
> >> +
> >> +	struct otg_fsm fsm;
> >> +	/* HCD, GCD and usb_otg_state are present in otg_fsm->otg
> >> +	 * HCD is bus_to_hcd(fsm->otg->host)
> >> +	 * GCD is fsm->otg->gadget
> >> +	 */
> >> +	struct otg_fsm_ops fsm_ops;	/* private copy for override */
> >> +	struct usb_otg otg;
> >> +	struct usb_hcd *shared_hcd;	/* if shared HCD registered */
> >> +
> >> +	/* saved hooks to OTG device */
> >> +	int (*start_host)(struct otg_fsm *fsm, int on);
> >> +	int (*start_gadget)(struct otg_fsm *fsm, int on);
> >> +
> >> +	struct list_head list;
> >> +
> >> +	struct work_struct work;	/* OTG FSM work */
> >> +	struct workqueue_struct *wq;
> >> +
> >> +	struct otg_timer timers[NUM_OTG_FSM_TIMERS];
> >> +
> >> +	bool fsm_running;
> >> +	bool gadget_can_start;		/* OTG FSM says gadget can start */
> >> +	bool host_can_start;		/* OTG FSM says host can start */
> >> +
> >> +	/* use otg->fsm.lock for serializing access */
> >> +};
> > 
> > What's the relationship between struct usb_otg otg and this one?
> 
> Did you mean why struct usb_otg otg is there in struct otg_data?
> Just for easy allocation. fsm_ops only contains the pointer to struct usb_otg.
> 

The reason why I ask this question is the most structures at usb_otg
(only enum usb_otg_state)are useless for otg_fsm, this structure may
only for hardware otg fsm driver, so your OTG framework should only
for software FSM drivers, right?

Peter

> > 
> >> +
> >> +/* OTG device list */
> >> +LIST_HEAD(otg_list);
> >> +static DEFINE_MUTEX(otg_list_mutex);
> >> +
> >> +/**
> >> + * check if device is in our OTG list and return
> >> + * otg_data, else NULL.
> >> + *
> >> + * otg_list_mutex must be held.
> >> + */
> >> +static struct otg_data *usb_otg_device_get_otgd(struct device *parent_dev)
> >> +{
> >> +	struct otg_data *otgd;
> >> +
> >> +	list_for_each_entry(otgd, &otg_list, list) {
> >> +		if (otgd->dev == parent_dev)
> >> +			return otgd;
> >> +	}
> >> +
> >> +	return NULL;
> >> +}
> >> +
> >> +/**
> >> + * timer callback to set timeout bit and kick FSM
> >> + */
> >> +static void set_tmout(unsigned long data)
> >> +{
> >> +	struct otg_timer *tmr_data;
> >> +
> >> +	tmr_data = (struct otg_timer *)data;
> >> +
> >> +	if (tmr_data->timeout_bit)
> >> +		*tmr_data->timeout_bit = 1;
> >> +
> >> +	usb_otg_sync_inputs(&tmr_data->otgd->fsm);
> >> +}
> >> +
> >> +/**
> >> + * Initialize one OTG timer with callback, timeout and timeout bit
> >> + */
> >> +static void otg_timer_init(enum otg_fsm_timer id, struct otg_data *otgd,
> >> +			   void (*callback)(unsigned long),
> >> +			   unsigned long expires_ms,
> >> +			   int *timeout_bit)
> >> +{
> >> +	struct otg_timer *otgtimer = &otgd->timers[id];
> >> +	struct timer_list *timer = &otgtimer->timer;
> >> +
> >> +	init_timer(timer);
> >> +	timer->function = callback;
> >> +	timer->expires = jiffies + msecs_to_jiffies(expires_ms);
> >> +	timer->data = (unsigned long)otgtimer;
> >> +
> > 
> > The timer for TB_DATA_PLS is about 10ms or less, it is not suitable
> > for using kernel timer, hrtimer is suitable choice.
> 
> good catch. I will switch to hrtimer then.
> 
> > 
> >> +	otgtimer->timeout_bit = timeout_bit;
> >> +	otgtimer->otgd = otgd;
> >> +}
> >> +
> >> +/**
> >> + * Initialize standard OTG timers
> >> + */
> >> +static void usb_otg_init_timers(struct otg_data *otgd)
> >> +{
> >> +	struct otg_fsm *fsm = &otgd->fsm;
> >> +
> >> +	otg_timer_init(A_WAIT_VRISE, otgd, set_tmout, TA_WAIT_VRISE, &fsm->a_wait_vrise_tmout);
> >> +	otg_timer_init(A_WAIT_VFALL, otgd, set_tmout, TA_WAIT_VFALL, &fsm->a_wait_vfall_tmout);
> >> +	otg_timer_init(A_WAIT_BCON, otgd, set_tmout, TA_WAIT_BCON, &fsm->a_wait_bcon_tmout);
> >> +	otg_timer_init(A_AIDL_BDIS, otgd, set_tmout, TA_AIDL_BDIS, &fsm->a_aidl_bdis_tmout);
> >> +	otg_timer_init(A_BIDL_ADIS, otgd, set_tmout, TA_BIDL_ADIS, &fsm->a_bidl_adis_tmout);
> >> +	otg_timer_init(B_ASE0_BRST, otgd, set_tmout, TB_ASE0_BRST, &fsm->b_ase0_brst_tmout);
> >> +
> >> +	otg_timer_init(B_SE0_SRP, otgd, set_tmout, TB_SE0_SRP, &fsm->b_se0_srp);
> >> +	otg_timer_init(B_SRP_FAIL, otgd, set_tmout, TB_SRP_FAIL, &fsm->b_srp_done);
> >> +
> >> +	otg_timer_init(A_WAIT_ENUM, otgd, set_tmout, TB_SRP_FAIL, NULL);
> >> +}
> 
> <snip>
> 
> cheers,
> -roger
> 

-- 

Best Regards,
Peter Chen
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