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Date: Fri, 17 Jul 2015 16:14:28 +0800
From: Li Jun <b47624@...escale.com>
To: Roger Quadros <rogerq@...com>
CC: <stern@...land.harvard.edu>, <balbi@...com>,
<gregkh@...uxfoundation.org>, <peter.chen@...escale.com>,
<dan.j.williams@...el.com>, <jun.li@...escale.com>,
<mathias.nyman@...ux.intel.com>, <tony@...mide.com>,
<Joao.Pinto@...opsys.com>, <linux-usb@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>
Subject: Re: [PATCH v3 10/11] usb: otg: Add dual-role device (DRD) support
Hi,
On Wed, Jul 08, 2015 at 01:19:36PM +0300, Roger Quadros wrote:
> DRD mode is a reduced functionality OTG mode. In this mode
> we don't support SRP, HNP and dynamic role-swap.
>
> In DRD operation, the controller mode (Host or Peripheral)
> is decided based on the ID pin status. Once a cable plug (Type-A
> or Type-B) is attached the controller selects the state
> and doesn't change till the cable in unplugged and a different
> cable type is inserted.
>
> As we don't need most of the complex OTG states and OTG timers
> we implement a lean DRD state machine in usb-otg.c.
> The DRD state machine is only interested in 2 hardware inputs
> 'id' and 'vbus; that are still passed via the origintal struct otg_fsm.
>
> Most of the usb-otg.c functionality remains the same except
> adding a new parameter to usb_otg_register() to indicate that
> the OTG controller needs to operate in DRD mode.
>
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
> drivers/usb/common/usb-otg.c | 179 ++++++++++++++++++++++++++++++++++++++++---
> include/linux/usb/otg-fsm.h | 8 +-
> include/linux/usb/otg.h | 5 +-
> 3 files changed, 180 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/usb/common/usb-otg.c b/drivers/usb/common/usb-otg.c
> index 1f19001..9b89f4b 100644
> --- a/drivers/usb/common/usb-otg.c
> +++ b/drivers/usb/common/usb-otg.c
> @@ -44,6 +44,7 @@ struct otg_hcd {
> struct otg_data {
> struct device *dev; /* HCD & GCD's parent device */
>
> + bool drd_only; /* Dual-role only, no OTG features */
After we introduce otg caps, we can use hnp_support to judge it it's
drd or OTG.
> struct otg_fsm fsm;
> /* HCD, GCD and usb_otg_state are present in otg_fsm->otg
> * HCD is bus_to_hcd(fsm->otg->host)
> @@ -272,20 +273,172 @@ static int usb_otg_start_gadget(struct otg_fsm *fsm, int on)
> return 0;
> }
>
> +/* Change USB protocol when there is a protocol change */
> +static int drd_set_protocol(struct otg_fsm *fsm, int protocol)
> +{
> + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
> + int ret = 0;
> +
> + if (fsm->protocol != protocol) {
> + dev_dbg(otgd->dev, "otg: changing role fsm->protocol= %d; new protocol= %d\n",
> + fsm->protocol, protocol);
> + /* stop old protocol */
> + if (fsm->protocol == PROTO_HOST)
> + ret = otg_start_host(fsm, 0);
> + else if (fsm->protocol == PROTO_GADGET)
> + ret = otg_start_gadget(fsm, 0);
> + if (ret)
> + return ret;
> +
> + /* start new protocol */
> + if (protocol == PROTO_HOST)
> + ret = otg_start_host(fsm, 1);
> + else if (protocol == PROTO_GADGET)
> + ret = otg_start_gadget(fsm, 1);
> + if (ret)
> + return ret;
> +
> + fsm->protocol = protocol;
> + return 0;
> + }
> +
> + return 0;
> +}
> +
> +/* Called when entering a DRD state */
> +static void drd_set_state(struct otg_fsm *fsm, enum usb_otg_state new_state)
> +{
> + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
> +
> + if (fsm->otg->state == new_state)
> + return;
> +
> + fsm->state_changed = 1;
> + dev_dbg(otgd->dev, "otg: set state: %s\n",
> + usb_otg_state_string(new_state));
> + switch (new_state) {
> + case OTG_STATE_B_IDLE:
otg_drv_vbus(fsm, 0);
> + drd_set_protocol(fsm, PROTO_UNDEF);
> + break;
> + case OTG_STATE_B_PERIPHERAL:
otg_drv_vbus(fsm, 0);
> + drd_set_protocol(fsm, PROTO_GADGET);
> + break;
> + case OTG_STATE_A_HOST:
otg_drv_vbus(fsm, 1);
> + drd_set_protocol(fsm, PROTO_HOST);
> + break;
> + case OTG_STATE_UNDEFINED:
> + case OTG_STATE_B_SRP_INIT:
> + case OTG_STATE_B_WAIT_ACON:
> + case OTG_STATE_B_HOST:
> + case OTG_STATE_A_IDLE:
> + case OTG_STATE_A_WAIT_VRISE:
> + case OTG_STATE_A_WAIT_BCON:
> + case OTG_STATE_A_SUSPEND:
> + case OTG_STATE_A_PERIPHERAL:
> + case OTG_STATE_A_WAIT_VFALL:
> + case OTG_STATE_A_VBUS_ERR:
> + default:
> + dev_warn(otgd->dev, "%s: otg: invalid state: %s\n",
> + __func__, usb_otg_state_string(new_state));
> + break;
> + }
> +
> + fsm->otg->state = new_state;
> +}
> +
> /**
> - * OTG FSM work function
> + * DRD state change judgement
> + *
> + * For DRD we're only interested in some of the OTG states
> + * i.e. OTG_STATE_B_IDLE: both peripheral and host are stopped
> + * OTG_STATE_B_PERIPHERAL: peripheral active
> + * OTG_STATE_A_HOST: host active
> + * we're only interested in the following inputs
> + * fsm->id, fsm->vbus
> + */
> +static int drd_statemachine(struct otg_fsm *fsm)
> +{
> + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
> + enum usb_otg_state state;
> +
> + mutex_lock(&fsm->lock);
> +
> + state = fsm->otg->state;
> +
> + switch (state) {
> + case OTG_STATE_UNDEFINED:
> + if (!fsm->id)
> + drd_set_state(fsm, OTG_STATE_A_HOST);
> + else if (fsm->id && fsm->vbus)
> + drd_set_state(fsm, OTG_STATE_B_PERIPHERAL);
> + else
> + drd_set_state(fsm, OTG_STATE_B_IDLE);
> + break;
> + case OTG_STATE_B_IDLE:
> + if (!fsm->id)
> + drd_set_state(fsm, OTG_STATE_A_HOST);
> + else if (fsm->vbus)
> + drd_set_state(fsm, OTG_STATE_B_PERIPHERAL);
> + break;
> + case OTG_STATE_B_PERIPHERAL:
> + if (!fsm->id)
> + drd_set_state(fsm, OTG_STATE_A_HOST);
> + else if (!fsm->vbus)
> + drd_set_state(fsm, OTG_STATE_B_IDLE);
> + break;
> + case OTG_STATE_A_HOST:
> + if (fsm->id && fsm->vbus)
> + drd_set_state(fsm, OTG_STATE_B_PERIPHERAL);
> + else if (fsm->id && !fsm->vbus)
> + drd_set_state(fsm, OTG_STATE_B_IDLE);
> + break;
> +
> + /* invalid states for DRD */
> + case OTG_STATE_B_SRP_INIT:
> + case OTG_STATE_B_WAIT_ACON:
> + case OTG_STATE_B_HOST:
> + case OTG_STATE_A_IDLE:
> + case OTG_STATE_A_WAIT_VRISE:
> + case OTG_STATE_A_WAIT_BCON:
> + case OTG_STATE_A_SUSPEND:
> + case OTG_STATE_A_PERIPHERAL:
> + case OTG_STATE_A_WAIT_VFALL:
> + case OTG_STATE_A_VBUS_ERR:
> + dev_err(otgd->dev, "%s: otg: invalid usb-drd state: %s\n",
> + __func__, usb_otg_state_string(state));
> + drd_set_state(fsm, OTG_STATE_UNDEFINED);
> + break;
> + }
> +
> + mutex_unlock(&fsm->lock);
> + dev_dbg(otgd->dev, "otg: quit statemachine, changed %d\n",
> + fsm->state_changed);
> +
> + return fsm->state_changed;
> +}
> +
> +/**
> + * OTG FSM/DRD work function
> */
> static void usb_otg_work(struct work_struct *work)
> {
> struct otg_data *otgd = container_of(work, struct otg_data, work);
>
> - otg_statemachine(&otgd->fsm);
> + /* OTG state machine */
> + if (!otgd->drd_only) {
> + otg_statemachine(&otgd->fsm);
> + return;
> + }
> +
> + /* DRD state machine */
> + drd_statemachine(&otgd->fsm);
> }
>
> /**
> * usb_otg_register() - Register the OTG device to OTG core
> * @parent_device: parent device of Host & Gadget controllers.
> * @otg_fsm_ops: otg state machine ops.
> + * @drd_only: dual-role only. no OTG features.
> *
> * Register parent device that contains both HCD and GCD into
> * the USB OTG core. HCD and GCD will be prevented from starting
> @@ -294,7 +447,8 @@ static void usb_otg_work(struct work_struct *work)
> * Return: struct otg_fsm * if success, NULL if error.
> */
> struct otg_fsm *usb_otg_register(struct device *parent_dev,
> - struct otg_fsm_ops *fsm_ops)
> + struct otg_fsm_ops *fsm_ops,
> + bool drd_only)
> {
> struct otg_data *otgd;
> int ret = 0;
> @@ -328,7 +482,15 @@ struct otg_fsm *usb_otg_register(struct device *parent_dev,
> goto err_wq;
> }
>
> - usb_otg_init_timers(otgd);
> + otgd->drd_only = drd_only;
> + /* For DRD mode we don't need OTG timers */
> + if (!drd_only) {
> + usb_otg_init_timers(otgd);
> +
> + /* FIXME: we ignore caller's timer ops */
> + otgd->fsm_ops.add_timer = usb_otg_add_timer;
> + otgd->fsm_ops.del_timer = usb_otg_del_timer;
> + }
>
> /* save original start host/gadget ops */
> otgd->start_host = fsm_ops->start_host;
> @@ -338,9 +500,6 @@ struct otg_fsm *usb_otg_register(struct device *parent_dev,
> /* override ops */
> otgd->fsm_ops.start_host = usb_otg_start_host;
> otgd->fsm_ops.start_gadget = usb_otg_start_gadget;
> - /* FIXME: we ignore caller's timer ops */
> - otgd->fsm_ops.add_timer = usb_otg_add_timer;
> - otgd->fsm_ops.del_timer = usb_otg_del_timer;
> /* set otg ops */
> otgd->fsm.ops = &otgd->fsm_ops;
> otgd->fsm.otg = &otgd->otg;
> @@ -443,8 +602,10 @@ static void usb_otg_stop_fsm(struct otg_fsm *fsm)
> otgd->fsm_running = false;
>
> /* Stop state machine / timers */
> - for (i = 0; i < ARRAY_SIZE(otgd->timers); i++)
> - hrtimer_cancel(&otgd->timers[i].timer);
> + if (!otgd->drd_only) {
> + for (i = 0; i < ARRAY_SIZE(otgd->timers); i++)
> + hrtimer_cancel(&otgd->timers[i].timer);
> + }
>
> flush_workqueue(otgd->wq);
> fsm->otg->state = OTG_STATE_UNDEFINED;
> diff --git a/include/linux/usb/otg-fsm.h b/include/linux/usb/otg-fsm.h
> index 22d8baa..ae9c30a 100644
> --- a/include/linux/usb/otg-fsm.h
> +++ b/include/linux/usb/otg-fsm.h
> @@ -48,6 +48,11 @@ enum otg_fsm_timer {
> /**
> * struct otg_fsm - OTG state machine according to the OTG spec
> *
> + * DRD mode hardware Inputs
> + *
> + * @id: TRUE for B-device, FALSE for A-device.
> + * @vbus: VBUS voltage in regulation.
> + *
> * OTG hardware Inputs
> *
> * Common inputs for A and B device
> @@ -122,7 +127,8 @@ enum otg_fsm_timer {
> */
> struct otg_fsm {
> /* Input */
> - int id;
> + int id; /* DRD + OTG */
> + int vbus; /* DRD only */
> int adp_change;
> int power_up;
> int a_srp_det;
> diff --git a/include/linux/usb/otg.h b/include/linux/usb/otg.h
> index ce6f8d8..1086a0b 100644
> --- a/include/linux/usb/otg.h
> +++ b/include/linux/usb/otg.h
> @@ -58,7 +58,7 @@ enum usb_dr_mode {
>
> #if IS_ENABLED(CONFIG_USB_OTG)
> struct otg_fsm *usb_otg_register(struct device *parent_dev,
> - struct otg_fsm_ops *fsm_ops);
> + struct otg_fsm_ops *fsm_ops, bool drd_only);
> int usb_otg_unregister(struct device *parent_dev);
> int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum,
> unsigned long irqflags, struct otg_hcd_ops *ops);
> @@ -73,7 +73,8 @@ struct device *usb_otg_fsm_to_dev(struct otg_fsm *fsm);
> #else /* CONFIG_USB_OTG */
>
> static inline struct otg_fsm *usb_otg_register(struct device *parent_dev,
> - struct otg_fsm_ops *fsm_ops)
> + struct otg_fsm_ops *fsm_ops,
> + bool drd_only)
> {
> return ERR_PTR(-ENOSYS);
> }
> --
> 2.1.4
>
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