drivers/net/phy/mii_timestamper.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 //
   3 // Support for generic time stamping devices on MII buses.
   4 // Copyright (C) 2018 Richard Cochran <richardcochran@gmail.com>
   5 //
   6
   7 #include <linux/mii_timestamper.h>
   8
   9 static LIST_HEAD(mii_timestamping_devices);
  10 static DEFINE_MUTEX(tstamping_devices_lock);
  11
  12 struct mii_timestamping_desc {
  13         struct list_head list;
  14         struct mii_timestamping_ctrl *ctrl;
  15         struct device *device;
  16 };
  17
  18 /**
  19  * register_mii_tstamp_controller() - registers an MII time stamping device.
  20  *
  21  * @device:     The device to be registered.
  22  * @ctrl:       Pointer to device's control interface.
  23  *
  24  * Returns zero on success or non-zero on failure.
  25  */
  26 int register_mii_tstamp_controller(struct device *device,
  27                                    struct mii_timestamping_ctrl *ctrl)
  28 {
  29         struct mii_timestamping_desc *desc;
  30
  31         desc = kzalloc(sizeof(*desc), GFP_KERNEL);
  32         if (!desc)
  33                 return -ENOMEM;
  34
  35         INIT_LIST_HEAD(&desc->list);
  36         desc->ctrl = ctrl;
  37         desc->device = device;
  38
  39         mutex_lock(&tstamping_devices_lock);
  40         list_add_tail(&mii_timestamping_devices, &desc->list);
  41         mutex_unlock(&tstamping_devices_lock);
  42
  43         return 0;
  44 }
  45 EXPORT_SYMBOL(register_mii_tstamp_controller);
  46
  47 /**
  48  * unregister_mii_tstamp_controller() - unregisters an MII time stamping device.
  49  *
  50  * @device:     A device previously passed to register_mii_tstamp_controller().
  51  */
  52 void unregister_mii_tstamp_controller(struct device *device)
  53 {
  54         struct mii_timestamping_desc *desc;
  55         struct list_head *this, *next;
  56
  57         mutex_lock(&tstamping_devices_lock);
  58         list_for_each_safe(this, next, &mii_timestamping_devices) {
  59                 desc = list_entry(this, struct mii_timestamping_desc, list);
  60                 if (desc->device == device) {
  61                         list_del_init(&desc->list);
  62                         kfree(desc);
  63                         break;
  64                 }
  65         }
  66         mutex_unlock(&tstamping_devices_lock);
  67 }
  68 EXPORT_SYMBOL(unregister_mii_tstamp_controller);
  69
  70 /**
  71  * register_mii_timestamper - Enables a given port of an MII time stamper.
  72  *
  73  * @node:       The device tree node of the MII time stamp controller.
  74  * @port:       The index of the port to be enabled.
  75  *
  76  * Returns a valid interface on success or ERR_PTR otherwise.
  77  */
  78 struct mii_timestamper *register_mii_timestamper(struct device_node *node,
  79                                                  unsigned int port)
  80 {
  81         struct mii_timestamper *mii_ts = NULL;
  82         struct mii_timestamping_desc *desc;
  83         struct list_head *this;
  84
  85         mutex_lock(&tstamping_devices_lock);
  86         list_for_each(this, &mii_timestamping_devices) {
  87                 desc = list_entry(this, struct mii_timestamping_desc, list);
  88                 if (desc->device->of_node == node) {
  89                         mii_ts = desc->ctrl->probe_channel(desc->device, port);
  90                         if (!IS_ERR(mii_ts)) {
  91                                 mii_ts->device = desc->device;
  92                                 get_device(desc->device);
  93                         }
  94                         break;
  95                 }
  96         }
  97         mutex_unlock(&tstamping_devices_lock);
  98
  99         return mii_ts ? mii_ts : ERR_PTR(-EPROBE_DEFER);
 100 }
 101 EXPORT_SYMBOL(register_mii_timestamper);
 102
 103 /**
 104  * unregister_mii_timestamper - Disables a given MII time stamper.
 105  *
 106  * @mii_ts:     An interface obtained via register_mii_timestamper().
 107  *
 108  */
 109 void unregister_mii_timestamper(struct mii_timestamper *mii_ts)
 110 {
 111         struct mii_timestamping_desc *desc;
 112         struct list_head *this;
 113
 114         /* mii_timestamper statically registered by the PHY driver won't use the
 115          * register_mii_timestamper() and thus don't have ->device set. Don't
 116          * try to unregister these.
 117          */
 118         if (!mii_ts->device)
 119                 return;
 120
 121         mutex_lock(&tstamping_devices_lock);
 122         list_for_each(this, &mii_timestamping_devices) {
 123                 desc = list_entry(this, struct mii_timestamping_desc, list);
 124                 if (desc->device == mii_ts->device) {
 125                         desc->ctrl->release_channel(desc->device, mii_ts);
 126                         put_device(desc->device);
 127                         break;
 128                 }
 129         }
 130         mutex_unlock(&tstamping_devices_lock);
 131 }
 132 EXPORT_SYMBOL(unregister_mii_timestamper);