drivers/usb/chipidea/otg.c

   1 /*
   2  * otg.c - ChipIdea USB IP core OTG driver
   3  *
   4  * Copyright (C) 2013 Freescale Semiconductor, Inc.
   5  *
   6  * Author: Peter Chen
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 /*
  14  * This file mainly handles otgsc register, it may include OTG operation
  15  * in the future.
  16  */
  17
  18 #include <linux/usb/otg.h>
  19 #include <linux/usb/gadget.h>
  20 #include <linux/usb/chipidea.h>
  21
  22 #include "ci.h"
  23 #include "bits.h"
  24 #include "otg.h"
  25
  26 /**
  27  * ci_otg_role - pick role based on ID pin state
  28  * @ci: the controller
  29  */
  30 enum ci_role ci_otg_role(struct ci_hdrc *ci)
  31 {
  32         u32 sts = hw_read(ci, OP_OTGSC, ~0);
  33         enum ci_role role = sts & OTGSC_ID
  34                 ? CI_ROLE_GADGET
  35                 : CI_ROLE_HOST;
  36
  37         return role;
  38 }
  39
  40 void ci_handle_vbus_change(struct ci_hdrc *ci)
  41 {
  42         u32 otgsc;
  43
  44         if (!ci->is_otg)
  45                 return;
  46
  47         otgsc = hw_read(ci, OP_OTGSC, ~0);
  48
  49         if (otgsc & OTGSC_BSV)
  50                 usb_gadget_vbus_connect(&ci->gadget);
  51         else
  52                 usb_gadget_vbus_disconnect(&ci->gadget);
  53 }
  54
  55 #define CI_VBUS_STABLE_TIMEOUT_MS 5000
  56 static void ci_handle_id_switch(struct ci_hdrc *ci)
  57 {
  58         enum ci_role role = ci_otg_role(ci);
  59
  60         if (role != ci->role) {
  61                 dev_dbg(ci->dev, "switching from %s to %s\n",
  62                         ci_role(ci)->name, ci->roles[role]->name);
  63
  64                 ci_role_stop(ci);
  65                 /* wait vbus lower than OTGSC_BSV */
  66                 hw_wait_reg(ci, OP_OTGSC, OTGSC_BSV, 0,
  67                                 CI_VBUS_STABLE_TIMEOUT_MS);
  68                 ci_role_start(ci, role);
  69         }
  70 }
  71 /**
  72  * ci_otg_work - perform otg (vbus/id) event handle
  73  * @work: work struct
  74  */
  75 static void ci_otg_work(struct work_struct *work)
  76 {
  77         struct ci_hdrc *ci = container_of(work, struct ci_hdrc, work);
  78
  79         if (ci->id_event) {
  80                 ci->id_event = false;
  81                 ci_handle_id_switch(ci);
  82         } else if (ci->b_sess_valid_event) {
  83                 ci->b_sess_valid_event = false;
  84                 ci_handle_vbus_change(ci);
  85         } else
  86                 dev_err(ci->dev, "unexpected event occurs at %s\n", __func__);
  87
  88         enable_irq(ci->irq);
  89 }
  90
  91
  92 /**
  93  * ci_hdrc_otg_init - initialize otg struct
  94  * ci: the controller
  95  */
  96 int ci_hdrc_otg_init(struct ci_hdrc *ci)
  97 {
  98         INIT_WORK(&ci->work, ci_otg_work);
  99         ci->wq = create_singlethread_workqueue("ci_otg");
 100         if (!ci->wq) {
 101                 dev_err(ci->dev, "can't create workqueue\n");
 102                 return -ENODEV;
 103         }
 104
 105         return 0;
 106 }
 107
 108 /**
 109  * ci_hdrc_otg_destroy - destroy otg struct
 110  * ci: the controller
 111  */
 112 void ci_hdrc_otg_destroy(struct ci_hdrc *ci)
 113 {
 114         if (ci->wq) {
 115                 flush_workqueue(ci->wq);
 116                 destroy_workqueue(ci->wq);
 117         }
 118         ci_disable_otg_interrupt(ci, OTGSC_INT_EN_BITS);
 119         ci_clear_otg_interrupt(ci, OTGSC_INT_STATUS_BITS);
 120 }