drivers/net/phy/mdio-mux.c

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