On Tue, Apr 05, 2016 at 05:05:12PM +0300, Roger Quadros wrote: > It provides APIs for the following tasks > > - Registering an OTG/dual-role capable controller > - Registering Host and Gadget controllers to OTG core > - Providing inputs to and kicking the OTG state machine > > Provide a dual-role device (DRD) state machine. > 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 'b_sess_vld'. > > Signed-off-by: Roger Quadros <rogerq@xxxxxx> > --- > drivers/usb/common/Makefile | 2 +- > drivers/usb/common/usb-otg.c | 1058 ++++++++++++++++++++++++++++++++++++++++++ > drivers/usb/common/usb-otg.h | 71 +++ > drivers/usb/core/Kconfig | 2 +- > include/linux/usb/gadget.h | 2 + > include/linux/usb/hcd.h | 1 + > include/linux/usb/otg-fsm.h | 7 + > include/linux/usb/otg.h | 154 +++++- > 8 files changed, 1292 insertions(+), 5 deletions(-) > create mode 100644 drivers/usb/common/usb-otg.c > create mode 100644 drivers/usb/common/usb-otg.h > > diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile > index f8f2c88..730d928 100644 > --- a/drivers/usb/common/Makefile > +++ b/drivers/usb/common/Makefile > @@ -7,5 +7,5 @@ usb-common-y += common.o > usb-common-$(CONFIG_USB_LED_TRIG) += led.o > > obj-$(CONFIG_USB_ULPI_BUS) += ulpi.o > -usbotg-y := usb-otg-fsm.o > +usbotg-y := usb-otg.o usb-otg-fsm.o > obj-$(CONFIG_USB_OTG) += usbotg.o > diff --git a/drivers/usb/common/usb-otg.c b/drivers/usb/common/usb-otg.c > new file mode 100644 > index 0000000..41e762a > --- /dev/null > +++ b/drivers/usb/common/usb-otg.c > @@ -0,0 +1,1058 @@ > +/** > + * drivers/usb/common/usb-otg.c - USB OTG core > + * > + * Copyright (C) 2016 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/ktime.h> > +#include <linux/hrtimer.h> > +#include <linux/list.h> > +#include <linux/of.h> > +#include <linux/of_platform.h> > +#include <linux/usb/otg.h> > +#include <linux/usb/gadget.h> > +#include <linux/workqueue.h> > + > +#include "usb-otg.h" > + > +struct otg_gcd { > + struct usb_gadget *gadget; > + struct otg_gadget_ops *ops; > +}; > + > +/* OTG device list */ > +LIST_HEAD(otg_list); > +static DEFINE_MUTEX(otg_list_mutex); > + > +/* Hosts and Gadgets waiting for OTG controller */ > +struct otg_wait_data { > + struct device *dev; /* OTG controller device */ > + > + struct otg_hcd primary_hcd; > + struct otg_hcd shared_hcd; > + struct otg_gcd gcd; > + struct list_head list; > +}; > + > +LIST_HEAD(wait_list); > +static DEFINE_MUTEX(wait_list_mutex); > + > +static int usb_otg_hcd_is_primary_hcd(struct usb_hcd *hcd) > +{ > + if (!hcd->primary_hcd) > + return 1; > + return hcd == hcd->primary_hcd; > +} Just find there is already a usb_hcd_is_primary_hcd at hcd.c, would you use it directly? Peter > + > +/** > + * Check if the OTG device is in our wait list and return > + * otg_wait_data, else NULL. > + * > + * wait_list_mutex must be held. > + */ > +static struct otg_wait_data *usb_otg_get_wait(struct device *otg_dev) > +{ > + struct otg_wait_data *wait; > + > + if (!otg_dev) > + return NULL; > + > + /* is there an entry for this otg_dev ?*/ > + list_for_each_entry(wait, &wait_list, list) { > + if (wait->dev == otg_dev) > + return wait; > + } > + > + return NULL; > +} > + > +/** > + * Add the hcd to our wait list > + */ > +static int usb_otg_hcd_wait_add(struct device *otg_dev, struct usb_hcd *hcd, > + unsigned int irqnum, unsigned long irqflags, > + struct otg_hcd_ops *ops) > +{ > + struct otg_wait_data *wait; > + int ret = -EINVAL; > + > + mutex_lock(&wait_list_mutex); > + > + wait = usb_otg_get_wait(otg_dev); > + if (!wait) { > + /* Not yet in wait list? allocate and add */ > + wait = kzalloc(sizeof(*wait), GFP_KERNEL); > + if (!wait) { > + ret = -ENOMEM; > + goto fail; > + } > + > + wait->dev = otg_dev; > + list_add_tail(&wait->list, &wait_list); > + } > + > + if (usb_otg_hcd_is_primary_hcd(hcd)) { > + if (wait->primary_hcd.hcd) /* already assigned? */ > + goto fail; > + > + wait->primary_hcd.hcd = hcd; > + wait->primary_hcd.irqnum = irqnum; > + wait->primary_hcd.irqflags = irqflags; > + wait->primary_hcd.ops = ops; > + wait->primary_hcd.otg_dev = otg_dev; > + } else { > + if (wait->shared_hcd.hcd) /* already assigned? */ > + goto fail; > + > + wait->shared_hcd.hcd = hcd; > + wait->shared_hcd.irqnum = irqnum; > + wait->shared_hcd.irqflags = irqflags; > + wait->shared_hcd.ops = ops; > + wait->shared_hcd.otg_dev = otg_dev; > + } > + > + mutex_unlock(&wait_list_mutex); > + return 0; > + > +fail: > + mutex_unlock(&wait_list_mutex); > + return ret; > +} > + > +/** > + * Check and free wait list entry if empty > + * > + * wait_list_mutex must be held > + */ > +static void usb_otg_check_free_wait(struct otg_wait_data *wait) > +{ > + if (wait->primary_hcd.hcd || wait->shared_hcd.hcd || wait->gcd.gadget) > + return; > + > + list_del(&wait->list); > + kfree(wait); > +} > + > +/** > + * Remove the hcd from our wait list > + */ > +static int usb_otg_hcd_wait_remove(struct usb_hcd *hcd) > +{ > + struct otg_wait_data *wait; > + > + mutex_lock(&wait_list_mutex); > + > + /* is there an entry for this hcd ?*/ > + list_for_each_entry(wait, &wait_list, list) { > + if (wait->primary_hcd.hcd == hcd) { > + wait->primary_hcd.hcd = 0; > + goto found; > + } else if (wait->shared_hcd.hcd == hcd) { > + wait->shared_hcd.hcd = 0; > + goto found; > + } > + } > + > + mutex_unlock(&wait_list_mutex); > + return -EINVAL; > + > +found: > + usb_otg_check_free_wait(wait); > + mutex_unlock(&wait_list_mutex); > + > + return 0; > +} > + > +/** > + * Add the gadget to our wait list > + */ > +static int usb_otg_gadget_wait_add(struct device *otg_dev, > + struct usb_gadget *gadget, > + struct otg_gadget_ops *ops) > +{ > + struct otg_wait_data *wait; > + int ret = -EINVAL; > + > + mutex_lock(&wait_list_mutex); > + > + wait = usb_otg_get_wait(otg_dev); > + if (!wait) { > + /* Not yet in wait list? allocate and add */ > + wait = kzalloc(sizeof(*wait), GFP_KERNEL); > + if (!wait) { > + ret = -ENOMEM; > + goto fail; > + } > + > + wait->dev = otg_dev; > + list_add_tail(&wait->list, &wait_list); > + } > + > + if (wait->gcd.gadget) /* already assigned? */ > + goto fail; > + > + wait->gcd.gadget = gadget; > + wait->gcd.ops = ops; > + mutex_unlock(&wait_list_mutex); > + > + return 0; > + > +fail: > + mutex_unlock(&wait_list_mutex); > + return ret; > +} > + > +/** > + * Remove the gadget from our wait list > + */ > +static int usb_otg_gadget_wait_remove(struct usb_gadget *gadget) > +{ > + struct otg_wait_data *wait; > + > + mutex_lock(&wait_list_mutex); > + > + /* is there an entry for this gadget ?*/ > + list_for_each_entry(wait, &wait_list, list) { > + if (wait->gcd.gadget == gadget) { > + wait->gcd.gadget = 0; > + goto found; > + } > + } > + > + mutex_unlock(&wait_list_mutex); > + > + return -EINVAL; > + > +found: > + usb_otg_check_free_wait(wait); > + mutex_unlock(&wait_list_mutex); > + > + return 0; > +} > + > +/** > + * Register pending host/gadget and remove entry from wait list > + */ > +static void usb_otg_flush_wait(struct device *otg_dev) > +{ > + struct otg_wait_data *wait; > + struct otg_hcd *host; > + struct otg_gcd *gadget; > + > + mutex_lock(&wait_list_mutex); > + > + wait = usb_otg_get_wait(otg_dev); > + if (!wait) > + goto done; > + > + dev_dbg(otg_dev, "otg: registering pending host/gadget\n"); > + gadget = &wait->gcd; > + if (gadget) > + usb_otg_register_gadget(gadget->gadget, gadget->ops); > + > + host = &wait->primary_hcd; > + if (host->hcd) > + usb_otg_register_hcd(host->hcd, host->irqnum, host->irqflags, > + host->ops); > + > + host = &wait->shared_hcd; > + if (host->hcd) > + usb_otg_register_hcd(host->hcd, host->irqnum, host->irqflags, > + host->ops); > + > + list_del(&wait->list); > + kfree(wait); > + > +done: > + mutex_unlock(&wait_list_mutex); > +} > + > +/** > + * Check if the OTG device is in our OTG list and return > + * usb_otg data, else NULL. > + * > + * otg_list_mutex must be held. > + */ > +static struct usb_otg *usb_otg_get_data(struct device *otg_dev) > +{ > + struct usb_otg *otg; > + > + if (!otg_dev) > + return NULL; > + > + list_for_each_entry(otg, &otg_list, list) { > + if (otg->dev == otg_dev) > + return otg; > + } > + > + return NULL; > +} > + > +/** > + * usb_otg_start_host - start/stop the host controller > + * @otg: usb_otg instance > + * @on: true to start, false to stop > + * > + * Start/stop the USB host controller. This function is meant > + * for use by the OTG controller driver. > + */ > +int usb_otg_start_host(struct usb_otg *otg, int on) > +{ > + struct otg_hcd_ops *hcd_ops = otg->hcd_ops; > + > + dev_dbg(otg->dev, "otg: %s %d\n", __func__, on); > + if (!otg->host) { > + WARN_ONCE(1, "otg: fsm running without host\n"); > + return 0; > + } > + > + if (on) { > + if (otg->flags & OTG_FLAG_HOST_RUNNING) > + return 0; > + > + otg->flags |= OTG_FLAG_HOST_RUNNING; > + > + /* start host */ > + hcd_ops->add(otg->primary_hcd.hcd, otg->primary_hcd.irqnum, > + otg->primary_hcd.irqflags); > + if (otg->shared_hcd.hcd) { > + hcd_ops->add(otg->shared_hcd.hcd, > + otg->shared_hcd.irqnum, > + otg->shared_hcd.irqflags); > + } > + } else { > + if (!(otg->flags & OTG_FLAG_HOST_RUNNING)) > + return 0; > + > + otg->flags &= ~OTG_FLAG_HOST_RUNNING; > + > + /* stop host */ > + if (otg->shared_hcd.hcd) > + hcd_ops->remove(otg->shared_hcd.hcd); > + > + hcd_ops->remove(otg->primary_hcd.hcd); > + } > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(usb_otg_start_host); > + > +/** > + * usb_otg_start_gadget - start/stop the gadget controller > + * @otg: usb_otg instance > + * @on: true to start, false to stop > + * > + * Start/stop the USB gadget controller. This function is meant > + * for use by the OTG controller driver. > + */ > +int usb_otg_start_gadget(struct usb_otg *otg, int on) > +{ > + struct usb_gadget *gadget = otg->gadget; > + > + dev_dbg(otg->dev, "otg: %s %d\n", __func__, on); > + if (!gadget) { > + WARN_ONCE(1, "otg: fsm running without gadget\n"); > + return 0; > + } > + > + if (on) { > + if (otg->flags & OTG_FLAG_GADGET_RUNNING) > + return 0; > + > + otg->flags |= OTG_FLAG_GADGET_RUNNING; > + otg->gadget_ops->start(otg->gadget); > + } else { > + if (!(otg->flags & OTG_FLAG_GADGET_RUNNING)) > + return 0; > + > + otg->flags &= ~OTG_FLAG_GADGET_RUNNING; > + otg->gadget_ops->stop(otg->gadget); > + } > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(usb_otg_start_gadget); > + > +/** > + * Change USB protocol when there is a protocol change. > + * fsm->lock must be held. > + */ > +static int drd_set_protocol(struct otg_fsm *fsm, int protocol) > +{ > + struct usb_otg *otg = container_of(fsm, struct usb_otg, fsm); > + int ret = 0; > + > + if (fsm->protocol != protocol) { > + dev_dbg(otg->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(otg, 0); > + else if (fsm->protocol == PROTO_GADGET) > + ret = otg_start_gadget(otg, 0); > + if (ret) > + return ret; > + > + /* start new protocol */ > + if (protocol == PROTO_HOST) > + ret = otg_start_host(otg, 1); > + else if (protocol == PROTO_GADGET) > + ret = otg_start_gadget(otg, 1); > + if (ret) > + return ret; > + > + fsm->protocol = protocol; > + return 0; > + } > + > + return 0; > +} > + > +/** > + * Called when entering a DRD state. > + * fsm->lock must be held. > + */ > +static void drd_set_state(struct otg_fsm *fsm, enum usb_otg_state new_state) > +{ > + struct usb_otg *otg = container_of(fsm, struct usb_otg, fsm); > + > + if (otg->state == new_state) > + return; > + > + fsm->state_changed = 1; > + dev_dbg(otg->dev, "otg: set state: %s\n", > + usb_otg_state_string(new_state)); > + switch (new_state) { > + case OTG_STATE_B_IDLE: > + drd_set_protocol(fsm, PROTO_UNDEF); > + otg_drv_vbus(otg, 0); > + break; > + case OTG_STATE_B_PERIPHERAL: > + drd_set_protocol(fsm, PROTO_GADGET); > + otg_drv_vbus(otg, 0); > + break; > + case OTG_STATE_A_HOST: > + drd_set_protocol(fsm, PROTO_HOST); > + otg_drv_vbus(otg, 1); > + 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(otg->dev, "%s: otg: invalid state: %s\n", > + __func__, usb_otg_state_string(new_state)); > + break; > + } > + > + otg->state = new_state; > +} > + > +/** > + * 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->b_sess_vld > + */ > +int drd_statemachine(struct usb_otg *otg) > +{ > + struct otg_fsm *fsm = &otg->fsm; > + enum usb_otg_state state; > + int ret; > + > + mutex_lock(&fsm->lock); > + > + fsm->state_changed = 0; > + state = otg->state; > + > + switch (state) { > + case OTG_STATE_UNDEFINED: > + if (!fsm->id) > + drd_set_state(fsm, OTG_STATE_A_HOST); > + else if (fsm->id && fsm->b_sess_vld) > + 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->b_sess_vld) > + 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->b_sess_vld) > + drd_set_state(fsm, OTG_STATE_B_IDLE); > + break; > + case OTG_STATE_A_HOST: > + if (fsm->id && fsm->b_sess_vld) > + drd_set_state(fsm, OTG_STATE_B_PERIPHERAL); > + else if (fsm->id && !fsm->b_sess_vld) > + 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(otg->dev, "%s: otg: invalid usb-drd state: %s\n", > + __func__, usb_otg_state_string(state)); > + drd_set_state(fsm, OTG_STATE_UNDEFINED); > + break; > + } > + > + ret = fsm->state_changed; > + mutex_unlock(&fsm->lock); > + dev_dbg(otg->dev, "otg: quit statemachine, changed %d\n", > + fsm->state_changed); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(drd_statemachine); > + > +/** > + * OTG FSM/DRD work function > + */ > +static void usb_otg_work(struct work_struct *work) > +{ > + struct usb_otg *otg = container_of(work, struct usb_otg, work); > + > + pm_runtime_get_sync(otg->dev); > + drd_statemachine(otg); > + pm_runtime_put_sync(otg->dev); > +} > + > +/** > + * usb_otg_register() - Register the OTG/dual-role device to OTG core > + * @dev: OTG/dual-role controller device. > + * @config: OTG configuration. > + * > + * Registers the OTG/dual-role controller device with the USB OTG core. > + * > + * Return: struct usb_otg * if success, ERR_PTR() if error. > + */ > +struct usb_otg *usb_otg_register(struct device *dev, > + struct usb_otg_config *config) > +{ > + struct usb_otg *otg; > + struct otg_wait_data *wait; > + int ret = 0; > + > + if (!dev || !config || !config->fsm_ops) > + return ERR_PTR(-EINVAL); > + > + /* already in list? */ > + mutex_lock(&otg_list_mutex); > + if (usb_otg_get_data(dev)) { > + dev_err(dev, "otg: %s: device already in otg list\n", > + __func__); > + ret = -EINVAL; > + goto unlock; > + } > + > + /* allocate and add to list */ > + otg = kzalloc(sizeof(*otg), GFP_KERNEL); > + if (!otg) { > + ret = -ENOMEM; > + goto unlock; > + } > + > + otg->dev = dev; > + otg->caps = config->otg_caps; > + > + if ((otg->caps->hnp_support || otg->caps->srp_support || > + otg->caps->adp_support) && !config->otg_work) > + dev_info(dev, "otg: limiting to dual-role\n"); > + > + if (config->otg_work) /* custom otg_work ? */ > + INIT_WORK(&otg->work, config->otg_work); > + else > + INIT_WORK(&otg->work, usb_otg_work); > + > + otg->wq = create_singlethread_workqueue("usb_otg"); > + if (!otg->wq) { > + dev_err(dev, "otg: %s: can't create workqueue\n", > + __func__); > + ret = -ENOMEM; > + goto err_wq; > + } > + > + /* set otg ops */ > + otg->fsm.ops = config->fsm_ops; > + > + mutex_init(&otg->fsm.lock); > + > + list_add_tail(&otg->list, &otg_list); > + mutex_unlock(&otg_list_mutex); > + > + /* were we in wait list? */ > + mutex_lock(&wait_list_mutex); > + wait = usb_otg_get_wait(dev); > + mutex_unlock(&wait_list_mutex); > + if (wait) { > + /* register pending host/gadget and flush from list */ > + usb_otg_flush_wait(dev); > + } > + > + return otg; > + > +err_wq: > + kfree(otg); > +unlock: > + mutex_unlock(&otg_list_mutex); > + return ERR_PTR(ret); > +} > +EXPORT_SYMBOL_GPL(usb_otg_register); > + > +/** > + * usb_otg_unregister() - Unregister the OTG/dual-role device from USB OTG core > + * @dev: OTG controller device. > + * > + * Unregisters the OTG/dual-role controller device from USB OTG core. > + * Prevents unregistering till both the associated Host and Gadget controllers > + * have unregistered from the OTG core. > + * > + * Return: 0 on success, error value otherwise. > + */ > +int usb_otg_unregister(struct device *dev) > +{ > + struct usb_otg *otg; > + > + mutex_lock(&otg_list_mutex); > + otg = usb_otg_get_data(dev); > + if (!otg) { > + dev_err(dev, "otg: %s: device not in otg list\n", > + __func__); > + mutex_unlock(&otg_list_mutex); > + return -EINVAL; > + } > + > + /* prevent unregister till both host & gadget have unregistered */ > + if (otg->host || otg->gadget) { > + dev_err(dev, "otg: %s: host/gadget still registered\n", > + __func__); > + return -EBUSY; > + } > + > + /* OTG FSM is halted when host/gadget unregistered */ > + destroy_workqueue(otg->wq); > + > + /* remove from otg list */ > + list_del(&otg->list); > + kfree(otg); > + mutex_unlock(&otg_list_mutex); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(usb_otg_unregister); > + > +/** > + * start/kick the OTG FSM if we can > + * fsm->lock must be held > + */ > +static void usb_otg_start_fsm(struct usb_otg *otg) > +{ > + struct otg_fsm *fsm = &otg->fsm; > + > + if (fsm->running) > + goto kick_fsm; > + > + if (!otg->host) { > + dev_info(otg->dev, "otg: can't start till host registers\n"); > + return; > + } > + > + if (!otg->gadget) { > + dev_info(otg->dev, "otg: can't start till gadget registers\n"); > + return; > + } > + > + fsm->running = true; > +kick_fsm: > + queue_work(otg->wq, &otg->work); > +} > + > +/** > + * stop the OTG FSM. Stops Host & Gadget controllers as well. > + * fsm->lock must be held > + */ > +static void usb_otg_stop_fsm(struct usb_otg *otg) > +{ > + struct otg_fsm *fsm = &otg->fsm; > + > + if (!fsm->running) > + return; > + > + /* no more new events queued */ > + fsm->running = false; > + > + flush_workqueue(otg->wq); > + otg->state = OTG_STATE_UNDEFINED; > + > + /* stop host/gadget immediately */ > + if (fsm->protocol == PROTO_HOST) > + otg_start_host(otg, 0); > + else if (fsm->protocol == PROTO_GADGET) > + otg_start_gadget(otg, 0); > + fsm->protocol = PROTO_UNDEF; > +} > + > +/** > + * usb_otg_sync_inputs - Sync OTG inputs with the OTG state machine > + * @fsm: OTG FSM instance > + * > + * Used by the OTG driver to update the inputs to the OTG > + * state machine. > + * > + * Can be called in IRQ context. > + */ > +void usb_otg_sync_inputs(struct usb_otg *otg) > +{ > + /* Don't kick FSM till it has started */ > + if (!otg->fsm.running) > + return; > + > + /* Kick FSM */ > + queue_work(otg->wq, &otg->work); > +} > +EXPORT_SYMBOL_GPL(usb_otg_sync_inputs); > + > +/** > + * usb_otg_kick_fsm - Kick the OTG state machine > + * @otg_dev: OTG controller device > + * > + * Used by USB host/device stack to sync OTG related > + * events to the OTG state machine. > + * e.g. change in host_bus->b_hnp_enable, gadget->b_hnp_enable > + * > + * Returns: 0 on success, error value otherwise. > + */ > +int usb_otg_kick_fsm(struct device *otg_dev) > +{ > + struct usb_otg *otg; > + > + mutex_lock(&otg_list_mutex); > + otg = usb_otg_get_data(otg_dev); > + mutex_unlock(&otg_list_mutex); > + if (!otg) { > + dev_dbg(otg_dev, "otg: %s: invalid otg device\n", > + __func__); > + return -ENODEV; > + } > + > + usb_otg_sync_inputs(otg); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(usb_otg_kick_fsm); > + > +/** > + * usb_otg_register_hcd - Register the host controller to OTG core > + * @hcd: host controller device > + * @irqnum: interrupt number > + * @irqflags: interrupt flags > + * @ops: HCD ops to interface with the HCD > + * > + * This is used by the USB Host stack to register the host controller > + * to the OTG core. Host controller must not be started by the > + * caller as it is left upto the OTG state machine to do so. > + * hcd->otg_dev must contain the related otg controller device. > + * > + * Returns: 0 on success, error value otherwise. > + */ > +int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum, > + unsigned long irqflags, struct otg_hcd_ops *ops) > +{ > + struct usb_otg *otg; > + struct device *hcd_dev = hcd->self.controller; > + struct device *otg_dev = hcd->otg_dev; > + > + if (!otg_dev) > + return -EINVAL; > + > + /* we're otg but otg controller might not yet be registered */ > + mutex_lock(&otg_list_mutex); > + otg = usb_otg_get_data(otg_dev); > + mutex_unlock(&otg_list_mutex); > + if (!otg) { > + dev_dbg(hcd_dev, > + "otg: controller not yet registered. waiting..\n"); > + /* > + * otg controller might register later. Put the hcd in > + * wait list and call us back when ready > + */ > + if (usb_otg_hcd_wait_add(otg_dev, hcd, irqnum, irqflags, ops)) { > + dev_err(hcd_dev, "otg: failed to add hcd to wait list\n"); > + return -EINVAL; > + } > + > + return 0; > + } > + > + /* HCD will be started by OTG fsm when needed */ > + mutex_lock(&otg->fsm.lock); > + if (otg->primary_hcd.hcd) { > + /* probably a shared HCD ? */ > + if (usb_otg_hcd_is_primary_hcd(hcd)) { > + dev_err(otg_dev, "otg: primary host already registered\n"); > + goto err; > + } > + > + if (hcd->shared_hcd == otg->primary_hcd.hcd) { > + if (otg->shared_hcd.hcd) { > + dev_err(otg_dev, "otg: shared host already registered\n"); > + goto err; > + } > + > + otg->shared_hcd.hcd = hcd; > + otg->shared_hcd.irqnum = irqnum; > + otg->shared_hcd.irqflags = irqflags; > + otg->shared_hcd.ops = ops; > + dev_info(otg_dev, "otg: shared host %s registered\n", > + dev_name(hcd->self.controller)); > + } else { > + dev_err(otg_dev, "otg: invalid shared host %s\n", > + dev_name(hcd->self.controller)); > + goto err; > + } > + } else { > + if (!usb_otg_hcd_is_primary_hcd(hcd)) { > + dev_err(otg_dev, "otg: primary host must be registered first\n"); > + goto err; > + } > + > + otg->primary_hcd.hcd = hcd; > + otg->primary_hcd.irqnum = irqnum; > + otg->primary_hcd.irqflags = irqflags; > + otg->primary_hcd.ops = ops; > + otg->hcd_ops = ops; > + dev_info(otg_dev, "otg: primary host %s registered\n", > + dev_name(hcd->self.controller)); > + } > + > + /* > + * we're ready only if we have shared HCD > + * or we don't need shared HCD. > + */ > + if (otg->shared_hcd.hcd || !otg->primary_hcd.hcd->shared_hcd) { > + otg->host = hcd_to_bus(hcd); > + /* FIXME: set bus->otg_port if this is true OTG port with HNP */ > + > + /* start FSM */ > + usb_otg_start_fsm(otg); > + } else { > + dev_dbg(otg_dev, "otg: can't start till shared host registers\n"); > + } > + > + mutex_unlock(&otg->fsm.lock); > + > + return 0; > + > +err: > + mutex_unlock(&otg->fsm.lock); > + return -EINVAL; > +} > +EXPORT_SYMBOL_GPL(usb_otg_register_hcd); > + > +/** > + * usb_otg_unregister_hcd - Unregister the host controller from OTG core > + * @hcd: host controller device > + * > + * This is used by the USB Host stack to unregister the host controller > + * from the OTG core. Ensures that host controller is not running > + * on successful return. > + * > + * Returns: 0 on success, error value otherwise. > + */ > +int usb_otg_unregister_hcd(struct usb_hcd *hcd) > +{ > + struct usb_otg *otg; > + struct device *hcd_dev = hcd_to_bus(hcd)->controller; > + struct device *otg_dev = hcd->otg_dev; > + > + if (!otg_dev) > + return -EINVAL; /* we're definitely not OTG */ > + > + mutex_lock(&otg_list_mutex); > + otg = usb_otg_get_data(otg_dev); > + mutex_unlock(&otg_list_mutex); > + if (!otg) { > + /* are we in wait list? */ > + if (!usb_otg_hcd_wait_remove(hcd)) > + return 0; > + > + dev_dbg(hcd_dev, "otg: host wasn't registered with otg\n"); > + return -EINVAL; > + } > + > + mutex_lock(&otg->fsm.lock); > + if (hcd == otg->primary_hcd.hcd) { > + otg->primary_hcd.hcd = NULL; > + dev_info(otg_dev, "otg: primary host %s unregistered\n", > + dev_name(hcd_dev)); > + } else if (hcd == otg->shared_hcd.hcd) { > + otg->shared_hcd.hcd = NULL; > + dev_info(otg_dev, "otg: shared host %s unregistered\n", > + dev_name(hcd_dev)); > + } else { > + dev_err(otg_dev, "otg: host %s wasn't registered with otg\n", > + dev_name(hcd_dev)); > + mutex_unlock(&otg->fsm.lock); > + return -EINVAL; > + } > + > + /* stop FSM & Host */ > + usb_otg_stop_fsm(otg); > + otg->host = NULL; > + > + mutex_unlock(&otg->fsm.lock); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(usb_otg_unregister_hcd); > + > +/** > + * usb_otg_register_gadget - Register the gadget controller to OTG core > + * @gadget: gadget controller > + * > + * This is used by the USB gadget stack to register the gadget controller > + * to the OTG core. Gadget controller must not be started by the > + * caller as it is left upto the OTG state machine to do so. > + * > + * Gadget core must call this only when all resources required for > + * gadget controller to run are available. > + * i.e. gadget function driver is available. > + * > + * Returns: 0 on success, error value otherwise. > + */ > +int usb_otg_register_gadget(struct usb_gadget *gadget, > + struct otg_gadget_ops *ops) > +{ > + struct usb_otg *otg; > + struct device *gadget_dev = &gadget->dev; > + struct device *otg_dev = gadget->otg_dev; > + > + if (!otg_dev) > + return -EINVAL; /* we're definitely not OTG */ > + > + /* we're otg but otg controller might not yet be registered */ > + mutex_lock(&otg_list_mutex); > + otg = usb_otg_get_data(otg_dev); > + mutex_unlock(&otg_list_mutex); > + if (!otg) { > + dev_dbg(gadget_dev, > + "otg: controller not yet registered. waiting..\n"); > + /* > + * otg controller might register later. Put the gadget in > + * wait list and call us back when ready > + */ > + if (usb_otg_gadget_wait_add(otg_dev, gadget, ops)) { > + dev_err(gadget_dev, > + "otg: failed to add to gadget to wait list\n"); > + return -EINVAL; > + } > + > + return 0; > + } > + > + mutex_lock(&otg->fsm.lock); > + if (otg->gadget) { > + dev_err(otg_dev, "otg: gadget already registered with otg\n"); > + mutex_unlock(&otg->fsm.lock); > + return -EINVAL; > + } > + > + otg->gadget = gadget; > + otg->gadget_ops = ops; > + dev_info(otg_dev, "otg: gadget %s registered\n", > + dev_name(&gadget->dev)); > + > + /* start FSM */ > + usb_otg_start_fsm(otg); > + mutex_unlock(&otg->fsm.lock); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(usb_otg_register_gadget); > + > +/** > + * usb_otg_unregister_gadget - Unregister the gadget controller from OTG core > + * @gadget: gadget controller > + * > + * This is used by the USB gadget stack to unregister the gadget controller > + * from the OTG core. Ensures that gadget controller is halted > + * on successful return. > + * > + * Returns: 0 on success, error value otherwise. > + */ > +int usb_otg_unregister_gadget(struct usb_gadget *gadget) > +{ > + struct usb_otg *otg; > + struct device *gadget_dev = &gadget->dev; > + struct device *otg_dev = gadget->otg_dev; > + > + if (!otg_dev) > + return -EINVAL; > + > + mutex_lock(&otg_list_mutex); > + otg = usb_otg_get_data(otg_dev); > + mutex_unlock(&otg_list_mutex); > + if (!otg) { > + /* are we in wait list? */ > + if (!usb_otg_gadget_wait_remove(gadget)) > + return 0; > + > + dev_dbg(gadget_dev, "otg: gadget wasn't registered with otg\n"); > + return -EINVAL; > + } > + > + mutex_lock(&otg->fsm.lock); > + if (otg->gadget != gadget) { > + dev_err(otg_dev, "otg: gadget %s wasn't registered with otg\n", > + dev_name(&gadget->dev)); > + mutex_unlock(&otg->fsm.lock); > + return -EINVAL; > + } > + > + /* Stop FSM & gadget */ > + usb_otg_stop_fsm(otg); > + otg->gadget = NULL; > + mutex_unlock(&otg->fsm.lock); > + > + dev_info(otg_dev, "otg: gadget %s unregistered\n", > + dev_name(&gadget->dev)); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(usb_otg_unregister_gadget); > diff --git a/drivers/usb/common/usb-otg.h b/drivers/usb/common/usb-otg.h > new file mode 100644 > index 0000000..2bf3fbf > --- /dev/null > +++ b/drivers/usb/common/usb-otg.h > @@ -0,0 +1,71 @@ > +/** > + * drivers/usb/common/usb-otg.h - USB OTG core local header > + * > + * Copyright (C) 2016 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. > + */ > + > +#ifndef __DRIVERS_USB_COMMON_USB_OTG_H > +#define __DRIVERS_USB_COMMON_USB_OTG_H > + > +/* > + * A-DEVICE timing constants > + */ > + > +/* Wait for VBUS Rise */ > +#define TA_WAIT_VRISE (100) /* a_wait_vrise: section 7.1.2 > + * a_wait_vrise_tmr: section 7.4.5.1 > + * TA_VBUS_RISE <= 100ms, section 4.4 > + * Table 4-1: Electrical Characteristics > + * ->DC Electrical Timing > + */ > +/* Wait for VBUS Fall */ > +#define TA_WAIT_VFALL (1000) /* a_wait_vfall: section 7.1.7 > + * a_wait_vfall_tmr: section: 7.4.5.2 > + */ > +/* Wait for B-Connect */ > +#define TA_WAIT_BCON (10000) /* a_wait_bcon: section 7.1.3 > + * TA_WAIT_BCON: should be between 1100 > + * and 30000 ms, section 5.5, Table 5-1 > + */ > +/* A-Idle to B-Disconnect */ > +#define TA_AIDL_BDIS (5000) /* a_suspend min 200 ms, section 5.2.1 > + * TA_AIDL_BDIS: section 5.5, Table 5-1 > + */ > +/* B-Idle to A-Disconnect */ > +#define TA_BIDL_ADIS (500) /* TA_BIDL_ADIS: section 5.2.1 > + * 500ms is used for B switch to host > + * for safe > + */ > + > +/* > + * B-device timing constants > + */ > + > +/* Data-Line Pulse Time*/ > +#define TB_DATA_PLS (10) /* b_srp_init,continue 5~10ms > + * section:5.1.3 > + */ > +/* SRP Fail Time */ > +#define TB_SRP_FAIL (6000) /* b_srp_init,fail time 5~6s > + * section:5.1.6 > + */ > +/* A-SE0 to B-Reset */ > +#define TB_ASE0_BRST (155) /* minimum 155 ms, section:5.3.1 */ > +/* SE0 Time Before SRP */ > +#define TB_SE0_SRP (1000) /* b_idle,minimum 1s, section:5.1.2 */ > +/* SSEND time before SRP */ > +#define TB_SSEND_SRP (1500) /* minimum 1.5 sec, section:5.1.2 */ > + > +#define TB_SESS_VLD (1000) > + > +#endif /* __DRIVERS_USB_COMMON_USB_OTG_H */ > diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig > index ae228d0..b468a9f 100644 > --- a/drivers/usb/core/Kconfig > +++ b/drivers/usb/core/Kconfig > @@ -42,7 +42,7 @@ config USB_DYNAMIC_MINORS > If you are unsure about this, say N here. > > config USB_OTG > - bool "OTG support" > + bool "OTG/Dual-role support" > depends on PM > default n > help > diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h > index 8c0ae64..1878ae1 100644 > --- a/include/linux/usb/gadget.h > +++ b/include/linux/usb/gadget.h > @@ -583,6 +583,7 @@ struct usb_gadget_ops { > * @out_epnum: last used out ep number > * @in_epnum: last used in ep number > * @otg_caps: OTG capabilities of this gadget. > + * @otg_dev: OTG controller device, if needs to be used with OTG core. > * @sg_supported: true if we can handle scatter-gather > * @is_otg: True if the USB device port uses a Mini-AB jack, so that the > * gadget driver must provide a USB OTG descriptor. > @@ -639,6 +640,7 @@ struct usb_gadget { > unsigned out_epnum; > unsigned in_epnum; > struct usb_otg_caps *otg_caps; > + struct device *otg_dev; > > unsigned sg_supported:1; > unsigned is_otg:1; > diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h > index 861ccaa..2017cd4 100644 > --- a/include/linux/usb/hcd.h > +++ b/include/linux/usb/hcd.h > @@ -184,6 +184,7 @@ struct usb_hcd { > struct mutex *bandwidth_mutex; > struct usb_hcd *shared_hcd; > struct usb_hcd *primary_hcd; > + struct device *otg_dev; /* OTG controller device */ > > > #define HCD_BUFFER_POOLS 4 > diff --git a/include/linux/usb/otg-fsm.h b/include/linux/usb/otg-fsm.h > index 36f0cf9..ba6755c 100644 > --- a/include/linux/usb/otg-fsm.h > +++ b/include/linux/usb/otg-fsm.h > @@ -61,6 +61,11 @@ 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. > + * @b_sess_vld: VBUS voltage in regulation. > + * > * OTG hardware Inputs > * > * Common inputs for A and B device > @@ -133,6 +138,7 @@ enum otg_fsm_timer { > * 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 > + * running: state machine running/stopped indicator > */ > struct otg_fsm { > /* Input */ > @@ -188,6 +194,7 @@ struct otg_fsm { > int b_ase0_brst_tmout; > int a_bidl_adis_tmout; > > + bool running; > struct otg_fsm_ops *ops; > > /* Current usb protocol used: 0:undefine; 1:host; 2:client */ > diff --git a/include/linux/usb/otg.h b/include/linux/usb/otg.h > index 85b8fb5..b094352 100644 > --- a/include/linux/usb/otg.h > +++ b/include/linux/usb/otg.h > @@ -10,10 +10,55 @@ > #define __LINUX_USB_OTG_H > > #include <linux/phy/phy.h> > -#include <linux/usb/phy.h> > -#include <linux/usb/otg-fsm.h> > +#include <linux/device.h> > +#include <linux/hrtimer.h> > +#include <linux/ktime.h> > +#include <linux/usb.h> > #include <linux/usb/hcd.h> > +#include <linux/usb/gadget.h> > +#include <linux/usb/otg-fsm.h> > +#include <linux/usb/phy.h> > > +/** > + * struct otg_hcd - host controller state and interface > + * > + * @hcd: host controller > + * @irqnum: irq number > + * @irqflags: irq flags > + * @ops: otg to host controller interface > + * @ops: otg to host controller interface > + * @otg_dev: otg controller device > + */ > +struct otg_hcd { > + struct usb_hcd *hcd; > + unsigned int irqnum; > + unsigned long irqflags; > + struct otg_hcd_ops *ops; > + struct device *otg_dev; > +}; > + > +/** > + * struct usb_otg - usb otg controller state > + * > + * @default_a: Indicates we are an A device. i.e. Host. > + * @phy: USB phy interface > + * @usb_phy: old usb_phy interface > + * @host: host controller bus > + * @gadget: gadget device > + * @state: current otg state > + * @dev: otg controller device > + * @caps: otg capabilities revision, hnp, srp, etc > + * @fsm: otg finite state machine > + * @hcd_ops: host controller interface > + * ------- internal use only ------- > + * @primary_hcd: primary host state and interface > + * @shared_hcd: shared host state and interface > + * @gadget_ops: gadget controller interface > + * @list: list of otg controllers > + * @work: otg state machine work > + * @wq: otg state machine work queue > + * @flags: to track if host/gadget is running > + */ > struct usb_otg { > u8 default_a; > > @@ -24,9 +69,24 @@ struct usb_otg { > struct usb_gadget *gadget; > > enum usb_otg_state state; > + struct device *dev; > + struct usb_otg_caps *caps; > struct otg_fsm fsm; > struct otg_hcd_ops *hcd_ops; > > + /* internal use only */ > + struct otg_hcd primary_hcd; > + struct otg_hcd shared_hcd; > + struct otg_gadget_ops *gadget_ops; > + struct list_head list; > + struct work_struct work; > + struct workqueue_struct *wq; > + u32 flags; > +#define OTG_FLAG_GADGET_RUNNING (1 << 0) > +#define OTG_FLAG_HOST_RUNNING (1 << 1) > + /* use otg->fsm.lock for serializing access */ > + > +/*------------- deprecated interface -----------------------------*/ > /* bind/unbind the host controller */ > int (*set_host)(struct usb_otg *otg, struct usb_bus *host); > > @@ -42,7 +102,7 @@ struct usb_otg { > > /* start or continue HNP role switch */ > int (*start_hnp)(struct usb_otg *otg); > - > +/*---------------------------------------------------------------*/ > }; > > /** > @@ -60,8 +120,92 @@ struct usb_otg_caps { > bool adp_support; > }; > > +/** > + * struct usb_otg_config - otg controller configuration > + * @caps: otg capabilities of the controller > + * @ops: otg fsm operations > + * @otg_work: optional custom otg state machine work function > + */ > +struct usb_otg_config { > + struct usb_otg_caps *otg_caps; > + struct otg_fsm_ops *fsm_ops; > + void (*otg_work)(struct work_struct *work); > +}; > + > extern const char *usb_otg_state_string(enum usb_otg_state state); > > +#if IS_ENABLED(CONFIG_USB_OTG) > +struct usb_otg *usb_otg_register(struct device *dev, > + struct usb_otg_config *config); > +int usb_otg_unregister(struct device *dev); > +int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum, > + unsigned long irqflags, struct otg_hcd_ops *ops); > +int usb_otg_unregister_hcd(struct usb_hcd *hcd); > +int usb_otg_register_gadget(struct usb_gadget *gadget, > + struct otg_gadget_ops *ops); > +int usb_otg_unregister_gadget(struct usb_gadget *gadget); > +void usb_otg_sync_inputs(struct usb_otg *otg); > +int usb_otg_kick_fsm(struct device *otg_dev); > +int usb_otg_start_host(struct usb_otg *otg, int on); > +int usb_otg_start_gadget(struct usb_otg *otg, int on); > + > +#else /* CONFIG_USB_OTG */ > + > +static inline struct usb_otg *usb_otg_register(struct device *dev, > + struct usb_otg_config *config) > +{ > + return ERR_PTR(-ENOTSUPP); > +} > + > +static inline int usb_otg_unregister(struct device *dev) > +{ > + return -ENOTSUPP; > +} > + > +static inline int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum, > + unsigned long irqflags, > + struct otg_hcd_ops *ops) > +{ > + return -ENOTSUPP; > +} > + > +static inline int usb_otg_unregister_hcd(struct usb_hcd *hcd) > +{ > + return -ENOTSUPP; > +} > + > +static inline int usb_otg_register_gadget(struct usb_gadget *gadget, > + struct otg_gadget_ops *ops) > +{ > + return -ENOTSUPP; > +} > + > +static inline int usb_otg_unregister_gadget(struct usb_gadget *gadget) > +{ > + return -ENOTSUPP; > +} > + > +static inline void usb_otg_sync_inputs(struct usb_otg *otg) > +{ > +} > + > +static inline int usb_otg_kick_fsm(struct device *otg_dev) > +{ > + return -ENOTSUPP; > +} > + > +static inline int usb_otg_start_host(struct usb_otg *otg, int on) > +{ > + return -ENOTSUPP; > +} > + > +static inline int usb_otg_start_gadget(struct usb_otg *otg, int on) > +{ > + return -ENOTSUPP; > +} > +#endif /* CONFIG_USB_OTG */ > + > +/*------------- deprecated interface -----------------------------*/ > /* Context: can sleep */ > static inline int > otg_start_hnp(struct usb_otg *otg) > @@ -113,6 +257,8 @@ otg_start_srp(struct usb_otg *otg) > return -ENOTSUPP; > } > > +/*---------------------------------------------------------------*/ > + > /* for OTG controller drivers (and maybe other stuff) */ > extern int usb_bus_start_enum(struct usb_bus *bus, unsigned port_num); > > @@ -237,4 +383,6 @@ static inline int otg_start_gadget(struct usb_otg *otg, int on) > return otg->fsm.ops->start_gadget(otg, on); > } > > +int drd_statemachine(struct usb_otg *otg); > + > #endif /* __LINUX_USB_OTG_H */ > -- > 2.5.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
