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_VERSION "1.0"
  17 #define DRV_DESCRIPTION "MDIO bus multiplexer driver"
  18
  19 struct mdio_mux_child_bus;
  20
  21 struct mdio_mux_parent_bus {
  22         struct mii_bus *mii_bus;
  23         int current_child;
  24         int parent_id;
  25         void *switch_data;
  26         int (*switch_fn)(int current_child, int desired_child, void *data);
  27
  28         /* List of our children linked through their next fields. */
  29         struct mdio_mux_child_bus *children;
  30 };
  31
  32 struct mdio_mux_child_bus {
  33         struct mii_bus *mii_bus;
  34         struct mdio_mux_parent_bus *parent;
  35         struct mdio_mux_child_bus *next;
  36         int bus_number;
  37 };
  38
  39 /*
  40  * The parent bus' lock is used to order access to the switch_fn.
  41  */
  42 static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
  43 {
  44         struct mdio_mux_child_bus *cb = bus->priv;
  45         struct mdio_mux_parent_bus *pb = cb->parent;
  46         int r;
  47
  48         mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
  49         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  50         if (r)
  51                 goto out;
  52
  53         pb->current_child = cb->bus_number;
  54
  55         r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
  56 out:
  57         mutex_unlock(&pb->mii_bus->mdio_lock);
  58
  59         return r;
  60 }
  61
  62 /*
  63  * The parent bus' lock is used to order access to the switch_fn.
  64  */
  65 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
  66                           int regnum, u16 val)
  67 {
  68         struct mdio_mux_child_bus *cb = bus->priv;
  69         struct mdio_mux_parent_bus *pb = cb->parent;
  70
  71         int r;
  72
  73         mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX);
  74         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  75         if (r)
  76                 goto out;
  77
  78         pb->current_child = cb->bus_number;
  79
  80         r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
  81 out:
  82         mutex_unlock(&pb->mii_bus->mdio_lock);
  83
  84         return r;
  85 }
  86
  87 static int parent_count;
  88
  89 int mdio_mux_init(struct device *dev,
  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 (!dev->of_node)
 103                 return -ENODEV;
 104
 105         if (!mux_bus) {
 106                 parent_bus_node = of_parse_phandle(dev->of_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         }
 121
 122         pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
 123         if (pb == NULL) {
 124                 ret_val = -ENOMEM;
 125                 goto err_parent_bus;
 126         }
 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(dev->of_node, child_bus_node) {
 137                 u32 v;
 138
 139                 r = of_property_read_u32(child_bus_node, "reg", &v);
 140                 if (r)
 141                         continue;
 142
 143                 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
 144                 if (cb == NULL) {
 145                         dev_err(dev,
 146                                 "Error: Failed to allocate memory for child\n");
 147                         ret_val = -ENOMEM;
 148                         of_node_put(child_bus_node);
 149                         break;
 150                 }
 151                 cb->bus_number = v;
 152                 cb->parent = pb;
 153
 154                 cb->mii_bus = mdiobus_alloc();
 155                 if (!cb->mii_bus) {
 156                         ret_val = -ENOMEM;
 157                         of_node_put(child_bus_node);
 158                         break;
 159                 }
 160                 cb->mii_bus->priv = cb;
 161
 162                 cb->mii_bus->name = "mdio_mux";
 163                 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
 164                          pb->parent_id, v);
 165                 cb->mii_bus->parent = dev;
 166                 cb->mii_bus->read = mdio_mux_read;
 167                 cb->mii_bus->write = mdio_mux_write;
 168                 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
 169                 if (r) {
 170                         mdiobus_free(cb->mii_bus);
 171                         devm_kfree(dev, cb);
 172                 } else {
 173                         of_node_get(child_bus_node);
 174                         cb->next = pb->children;
 175                         pb->children = cb;
 176                 }
 177         }
 178         if (pb->children) {
 179                 *mux_handle = pb;
 180                 dev_info(dev, "Version " DRV_VERSION "\n");
 181                 return 0;
 182         }
 183
 184         /* balance the reference of_mdio_find_bus() took */
 185         put_device(&pb->mii_bus->dev);
 186
 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         /* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
 205         put_device(&pb->mii_bus->dev);
 206 }
 207 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
 208
 209 MODULE_DESCRIPTION(DRV_DESCRIPTION);
 210 MODULE_VERSION(DRV_VERSION);
 211 MODULE_AUTHOR("David Daney");
 212 MODULE_LICENSE("GPL");