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 {
  94         struct device_node *parent_bus_node;
  95         struct device_node *child_bus_node;
  96         int r, ret_val;
  97         struct mii_bus *parent_bus;
  98         struct mdio_mux_parent_bus *pb;
  99         struct mdio_mux_child_bus *cb;
 100
 101         if (!dev->of_node)
 102                 return -ENODEV;
 103
 104         parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
 105
 106         if (!parent_bus_node)
 107                 return -ENODEV;
 108
 109         pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
 110         if (pb == NULL) {
 111                 ret_val = -ENOMEM;
 112                 goto err_parent_bus;
 113         }
 114
 115         parent_bus = of_mdio_find_bus(parent_bus_node);
 116         if (parent_bus == NULL) {
 117                 ret_val = -EPROBE_DEFER;
 118                 goto err_parent_bus;
 119         }
 120
 121         pb->switch_data = data;
 122         pb->switch_fn = switch_fn;
 123         pb->current_child = -1;
 124         pb->parent_id = parent_count++;
 125         pb->mii_bus = parent_bus;
 126
 127         ret_val = -ENODEV;
 128         for_each_available_child_of_node(dev->of_node, child_bus_node) {
 129                 u32 v;
 130
 131                 r = of_property_read_u32(child_bus_node, "reg", &v);
 132                 if (r)
 133                         continue;
 134
 135                 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
 136                 if (cb == NULL) {
 137                         dev_err(dev,
 138                                 "Error: Failed to allocate memory for child\n");
 139                         ret_val = -ENOMEM;
 140                         of_node_put(child_bus_node);
 141                         break;
 142                 }
 143                 cb->bus_number = v;
 144                 cb->parent = pb;
 145
 146                 cb->mii_bus = mdiobus_alloc();
 147                 if (!cb->mii_bus) {
 148                         ret_val = -ENOMEM;
 149                         of_node_put(child_bus_node);
 150                         break;
 151                 }
 152                 cb->mii_bus->priv = cb;
 153
 154                 cb->mii_bus->name = "mdio_mux";
 155                 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
 156                          pb->parent_id, v);
 157                 cb->mii_bus->parent = dev;
 158                 cb->mii_bus->read = mdio_mux_read;
 159                 cb->mii_bus->write = mdio_mux_write;
 160                 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
 161                 if (r) {
 162                         mdiobus_free(cb->mii_bus);
 163                         devm_kfree(dev, cb);
 164                 } else {
 165                         of_node_get(child_bus_node);
 166                         cb->next = pb->children;
 167                         pb->children = cb;
 168                 }
 169         }
 170         if (pb->children) {
 171                 *mux_handle = pb;
 172                 dev_info(dev, "Version " DRV_VERSION "\n");
 173                 return 0;
 174         }
 175
 176         /* balance the reference of_mdio_find_bus() took */
 177         put_device(&pb->mii_bus->dev);
 178
 179 err_parent_bus:
 180         of_node_put(parent_bus_node);
 181         return ret_val;
 182 }
 183 EXPORT_SYMBOL_GPL(mdio_mux_init);
 184
 185 void mdio_mux_uninit(void *mux_handle)
 186 {
 187         struct mdio_mux_parent_bus *pb = mux_handle;
 188         struct mdio_mux_child_bus *cb = pb->children;
 189
 190         while (cb) {
 191                 mdiobus_unregister(cb->mii_bus);
 192                 mdiobus_free(cb->mii_bus);
 193                 cb = cb->next;
 194         }
 195
 196         /* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
 197         put_device(&pb->mii_bus->dev);
 198 }
 199 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
 200
 201 MODULE_DESCRIPTION(DRV_DESCRIPTION);
 202 MODULE_VERSION(DRV_VERSION);
 203 MODULE_AUTHOR("David Daney");
 204 MODULE_LICENSE("GPL");