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         /* In theory multiple mdio_mux could be stacked, thus creating
  49          * more than a single level of nesting.  But in practice,
  50          * SINGLE_DEPTH_NESTING will cover the vast majority of use
  51          * cases.  We use it, instead of trying to handle the general
  52          * case.
  53          */
  54         mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
  55         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  56         if (r)
  57                 goto out;
  58
  59         pb->current_child = cb->bus_number;
  60
  61         r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
  62 out:
  63         mutex_unlock(&pb->mii_bus->mdio_lock);
  64
  65         return r;
  66 }
  67
  68 /*
  69  * The parent bus' lock is used to order access to the switch_fn.
  70  */
  71 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
  72                           int regnum, u16 val)
  73 {
  74         struct mdio_mux_child_bus *cb = bus->priv;
  75         struct mdio_mux_parent_bus *pb = cb->parent;
  76
  77         int r;
  78
  79         mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
  80         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  81         if (r)
  82                 goto out;
  83
  84         pb->current_child = cb->bus_number;
  85
  86         r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
  87 out:
  88         mutex_unlock(&pb->mii_bus->mdio_lock);
  89
  90         return r;
  91 }
  92
  93 static int parent_count;
  94
  95 int mdio_mux_init(struct device *dev,
  96                   int (*switch_fn)(int cur, int desired, void *data),
  97                   void **mux_handle,
  98                   void *data)
  99 {
 100         struct device_node *parent_bus_node;
 101         struct device_node *child_bus_node;
 102         int r, ret_val;
 103         struct mii_bus *parent_bus;
 104         struct mdio_mux_parent_bus *pb;
 105         struct mdio_mux_child_bus *cb;
 106
 107         if (!dev->of_node)
 108                 return -ENODEV;
 109
 110         parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
 111
 112         if (!parent_bus_node)
 113                 return -ENODEV;
 114
 115         pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
 116         if (pb == NULL) {
 117                 ret_val = -ENOMEM;
 118                 goto err_parent_bus;
 119         }
 120
 121         parent_bus = of_mdio_find_bus(parent_bus_node);
 122         if (parent_bus == NULL) {
 123                 ret_val = -EPROBE_DEFER;
 124                 goto err_parent_bus;
 125         }
 126
 127         pb->switch_data = data;
 128         pb->switch_fn = switch_fn;
 129         pb->current_child = -1;
 130         pb->parent_id = parent_count++;
 131         pb->mii_bus = parent_bus;
 132
 133         ret_val = -ENODEV;
 134         for_each_available_child_of_node(dev->of_node, child_bus_node) {
 135                 u32 v;
 136
 137                 r = of_property_read_u32(child_bus_node, "reg", &v);
 138                 if (r)
 139                         continue;
 140
 141                 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
 142                 if (cb == NULL) {
 143                         dev_err(dev,
 144                                 "Error: Failed to allocate memory for child\n");
 145                         ret_val = -ENOMEM;
 146                         of_node_put(child_bus_node);
 147                         break;
 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                         of_node_put(child_bus_node);
 156                         break;
 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                         mdiobus_free(cb->mii_bus);
 169                         devm_kfree(dev, cb);
 170                 } else {
 171                         of_node_get(child_bus_node);
 172                         cb->next = pb->children;
 173                         pb->children = cb;
 174                 }
 175         }
 176         if (pb->children) {
 177                 *mux_handle = pb;
 178                 dev_info(dev, "Version " DRV_VERSION "\n");
 179                 return 0;
 180         }
 181
 182         /* balance the reference of_mdio_find_bus() took */
 183         put_device(&pb->mii_bus->dev);
 184
 185 err_parent_bus:
 186         of_node_put(parent_bus_node);
 187         return ret_val;
 188 }
 189 EXPORT_SYMBOL_GPL(mdio_mux_init);
 190
 191 void mdio_mux_uninit(void *mux_handle)
 192 {
 193         struct mdio_mux_parent_bus *pb = mux_handle;
 194         struct mdio_mux_child_bus *cb = pb->children;
 195
 196         while (cb) {
 197                 mdiobus_unregister(cb->mii_bus);
 198                 mdiobus_free(cb->mii_bus);
 199                 cb = cb->next;
 200         }
 201
 202         /* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
 203         put_device(&pb->mii_bus->dev);
 204 }
 205 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
 206
 207 MODULE_DESCRIPTION(DRV_DESCRIPTION);
 208 MODULE_VERSION(DRV_VERSION);
 209 MODULE_AUTHOR("David Daney");
 210 MODULE_LICENSE("GPL");