drivers/net/phy/mdio-mux.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2011, 2012 Cavium, Inc.
   4  */
   5
   6 #include <linux/platform_device.h>
   7 #include <linux/mdio-mux.h>
   8 #include <linux/of_mdio.h>
   9 #include <linux/device.h>
  10 #include <linux/module.h>
  11 #include <linux/phy.h>
  12
  13 #define DRV_DESCRIPTION "MDIO bus multiplexer driver"
  14
  15 struct mdio_mux_child_bus;
  16
  17 struct mdio_mux_parent_bus {
  18         struct mii_bus *mii_bus;
  19         int current_child;
  20         int parent_id;
  21         void *switch_data;
  22         int (*switch_fn)(int current_child, int desired_child, void *data);
  23
  24         /* List of our children linked through their next fields. */
  25         struct mdio_mux_child_bus *children;
  26 };
  27
  28 struct mdio_mux_child_bus {
  29         struct mii_bus *mii_bus;
  30         struct mdio_mux_parent_bus *parent;
  31         struct mdio_mux_child_bus *next;
  32         int bus_number;
  33 };
  34
  35 /*
  36  * The parent bus' lock is used to order access to the switch_fn.
  37  */
  38 static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
  39 {
  40         struct mdio_mux_child_bus *cb = bus->priv;
  41         struct mdio_mux_parent_bus *pb = cb->parent;
  42         int r;
  43
  44         mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
  45         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  46         if (r)
  47                 goto out;
  48
  49         pb->current_child = cb->bus_number;
  50
  51         r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
  52 out:
  53         mutex_unlock(&pb->mii_bus->mdio_lock);
  54
  55         return r;
  56 }
  57
  58 /*
  59  * The parent bus' lock is used to order access to the switch_fn.
  60  */
  61 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
  62                           int regnum, u16 val)
  63 {
  64         struct mdio_mux_child_bus *cb = bus->priv;
  65         struct mdio_mux_parent_bus *pb = cb->parent;
  66
  67         int r;
  68
  69         mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
  70         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  71         if (r)
  72                 goto out;
  73
  74         pb->current_child = cb->bus_number;
  75
  76         r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
  77 out:
  78         mutex_unlock(&pb->mii_bus->mdio_lock);
  79
  80         return r;
  81 }
  82
  83 static int parent_count;
  84
  85 int mdio_mux_init(struct device *dev,
  86                   struct device_node *mux_node,
  87                   int (*switch_fn)(int cur, int desired, void *data),
  88                   void **mux_handle,
  89                   void *data,
  90                   struct mii_bus *mux_bus)
  91 {
  92         struct device_node *parent_bus_node;
  93         struct device_node *child_bus_node;
  94         int r, ret_val;
  95         struct mii_bus *parent_bus;
  96         struct mdio_mux_parent_bus *pb;
  97         struct mdio_mux_child_bus *cb;
  98
  99         if (!mux_node)
 100                 return -ENODEV;
 101
 102         if (!mux_bus) {
 103                 parent_bus_node = of_parse_phandle(mux_node,
 104                                                    "mdio-parent-bus", 0);
 105
 106                 if (!parent_bus_node)
 107                         return -ENODEV;
 108
 109                 parent_bus = of_mdio_find_bus(parent_bus_node);
 110                 if (!parent_bus) {
 111                         ret_val = -EPROBE_DEFER;
 112                         goto err_parent_bus;
 113                 }
 114         } else {
 115                 parent_bus_node = NULL;
 116                 parent_bus = mux_bus;
 117                 get_device(&parent_bus->dev);
 118         }
 119
 120         pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
 121         if (!pb) {
 122                 ret_val = -ENOMEM;
 123                 goto err_pb_kz;
 124         }
 125
 126         pb->switch_data = data;
 127         pb->switch_fn = switch_fn;
 128         pb->current_child = -1;
 129         pb->parent_id = parent_count++;
 130         pb->mii_bus = parent_bus;
 131
 132         ret_val = -ENODEV;
 133         for_each_available_child_of_node(mux_node, child_bus_node) {
 134                 int v;
 135
 136                 r = of_property_read_u32(child_bus_node, "reg", &v);
 137                 if (r) {
 138                         dev_err(dev,
 139                                 "Error: Failed to find reg for child %pOF\n",
 140                                 child_bus_node);
 141                         continue;
 142                 }
 143
 144                 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
 145                 if (!cb) {
 146                         ret_val = -ENOMEM;
 147                         continue;
 148                 }
 149                 cb->bus_number = v;
 150                 cb->parent = pb;
 151
 152                 cb->mii_bus = mdiobus_alloc();
 153                 if (!cb->mii_bus) {
 154                         ret_val = -ENOMEM;
 155                         devm_kfree(dev, cb);
 156                         continue;
 157                 }
 158                 cb->mii_bus->priv = cb;
 159
 160                 cb->mii_bus->name = "mdio_mux";
 161                 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
 162                          pb->parent_id, v);
 163                 cb->mii_bus->parent = dev;
 164                 cb->mii_bus->read = mdio_mux_read;
 165                 cb->mii_bus->write = mdio_mux_write;
 166                 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
 167                 if (r) {
 168                         dev_err(dev,
 169                                 "Error: Failed to register MDIO bus for child %pOF\n",
 170                                 child_bus_node);
 171                         mdiobus_free(cb->mii_bus);
 172                         devm_kfree(dev, cb);
 173                 } else {
 174                         cb->next = pb->children;
 175                         pb->children = cb;
 176                 }
 177         }
 178         if (pb->children) {
 179                 *mux_handle = pb;
 180                 return 0;
 181         }
 182
 183         dev_err(dev, "Error: No acceptable child buses found\n");
 184         devm_kfree(dev, pb);
 185 err_pb_kz:
 186         put_device(&parent_bus->dev);
 187 err_parent_bus:
 188         of_node_put(parent_bus_node);
 189         return ret_val;
 190 }
 191 EXPORT_SYMBOL_GPL(mdio_mux_init);
 192
 193 void mdio_mux_uninit(void *mux_handle)
 194 {
 195         struct mdio_mux_parent_bus *pb = mux_handle;
 196         struct mdio_mux_child_bus *cb = pb->children;
 197
 198         while (cb) {
 199                 mdiobus_unregister(cb->mii_bus);
 200                 mdiobus_free(cb->mii_bus);
 201                 cb = cb->next;
 202         }
 203
 204         put_device(&pb->mii_bus->dev);
 205 }
 206 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
 207
 208 MODULE_DESCRIPTION(DRV_DESCRIPTION);
 209 MODULE_AUTHOR("David Daney");
 210 MODULE_LICENSE("GPL v2");