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         int phy_irq[PHY_MAX_ADDR];
  38 };
  39
  40 /*
  41  * The parent bus' lock is used to order access to the switch_fn.
  42  */
  43 static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum)
  44 {
  45         struct mdio_mux_child_bus *cb = bus->priv;
  46         struct mdio_mux_parent_bus *pb = cb->parent;
  47         int r;
  48
  49         /* In theory multiple mdio_mux could be stacked, thus creating
  50          * more than a single level of nesting.  But in practice,
  51          * SINGLE_DEPTH_NESTING will cover the vast majority of use
  52          * cases.  We use it, instead of trying to handle the general
  53          * case.
  54          */
  55         mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
  56         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  57         if (r)
  58                 goto out;
  59
  60         pb->current_child = cb->bus_number;
  61
  62         r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum);
  63 out:
  64         mutex_unlock(&pb->mii_bus->mdio_lock);
  65
  66         return r;
  67 }
  68
  69 /*
  70  * The parent bus' lock is used to order access to the switch_fn.
  71  */
  72 static int mdio_mux_write(struct mii_bus *bus, int phy_id,
  73                           int regnum, u16 val)
  74 {
  75         struct mdio_mux_child_bus *cb = bus->priv;
  76         struct mdio_mux_parent_bus *pb = cb->parent;
  77
  78         int r;
  79
  80         mutex_lock_nested(&pb->mii_bus->mdio_lock, SINGLE_DEPTH_NESTING);
  81         r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data);
  82         if (r)
  83                 goto out;
  84
  85         pb->current_child = cb->bus_number;
  86
  87         r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val);
  88 out:
  89         mutex_unlock(&pb->mii_bus->mdio_lock);
  90
  91         return r;
  92 }
  93
  94 static int parent_count;
  95
  96 int mdio_mux_init(struct device *dev,
  97                   int (*switch_fn)(int cur, int desired, void *data),
  98                   void **mux_handle,
  99                   void *data)
 100 {
 101         struct device_node *parent_bus_node;
 102         struct device_node *child_bus_node;
 103         int r, ret_val;
 104         struct mii_bus *parent_bus;
 105         struct mdio_mux_parent_bus *pb;
 106         struct mdio_mux_child_bus *cb;
 107
 108         if (!dev->of_node)
 109                 return -ENODEV;
 110
 111         parent_bus_node = of_parse_phandle(dev->of_node, "mdio-parent-bus", 0);
 112
 113         if (!parent_bus_node)
 114                 return -ENODEV;
 115
 116         pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL);
 117         if (pb == NULL) {
 118                 ret_val = -ENOMEM;
 119                 goto err_parent_bus;
 120         }
 121
 122         parent_bus = of_mdio_find_bus(parent_bus_node);
 123         if (parent_bus == NULL) {
 124                 ret_val = -EPROBE_DEFER;
 125                 goto err_parent_bus;
 126         }
 127
 128         pb->switch_data = data;
 129         pb->switch_fn = switch_fn;
 130         pb->current_child = -1;
 131         pb->parent_id = parent_count++;
 132         pb->mii_bus = parent_bus;
 133
 134         ret_val = -ENODEV;
 135         for_each_available_child_of_node(dev->of_node, child_bus_node) {
 136                 u32 v;
 137
 138                 r = of_property_read_u32(child_bus_node, "reg", &v);
 139                 if (r)
 140                         continue;
 141
 142                 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL);
 143                 if (cb == NULL) {
 144                         dev_err(dev,
 145                                 "Error: Failed to allocate memory for child\n");
 146                         ret_val = -ENOMEM;
 147                         of_node_put(child_bus_node);
 148                         break;
 149                 }
 150                 cb->bus_number = v;
 151                 cb->parent = pb;
 152
 153                 cb->mii_bus = mdiobus_alloc();
 154                 if (!cb->mii_bus) {
 155                         ret_val = -ENOMEM;
 156                         of_node_put(child_bus_node);
 157                         break;
 158                 }
 159                 cb->mii_bus->priv = cb;
 160                 cb->mii_bus->irq = cb->phy_irq;
 161                 cb->mii_bus->name = "mdio_mux";
 162                 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%x.%x",
 163                          pb->parent_id, v);
 164                 cb->mii_bus->parent = dev;
 165                 cb->mii_bus->read = mdio_mux_read;
 166                 cb->mii_bus->write = mdio_mux_write;
 167                 r = of_mdiobus_register(cb->mii_bus, child_bus_node);
 168                 if (r) {
 169                         mdiobus_free(cb->mii_bus);
 170                         devm_kfree(dev, cb);
 171                 } else {
 172                         of_node_get(child_bus_node);
 173                         cb->next = pb->children;
 174                         pb->children = cb;
 175                 }
 176         }
 177         if (pb->children) {
 178                 *mux_handle = pb;
 179                 dev_info(dev, "Version " DRV_VERSION "\n");
 180                 return 0;
 181         }
 182
 183         /* balance the reference of_mdio_find_bus() took */
 184         put_device(&pb->mii_bus->dev);
 185
 186 err_parent_bus:
 187         of_node_put(parent_bus_node);
 188         return ret_val;
 189 }
 190 EXPORT_SYMBOL_GPL(mdio_mux_init);
 191
 192 void mdio_mux_uninit(void *mux_handle)
 193 {
 194         struct mdio_mux_parent_bus *pb = mux_handle;
 195         struct mdio_mux_child_bus *cb = pb->children;
 196
 197         while (cb) {
 198                 mdiobus_unregister(cb->mii_bus);
 199                 mdiobus_free(cb->mii_bus);
 200                 cb = cb->next;
 201         }
 202
 203         /* balance the reference of_mdio_find_bus() in mdio_mux_init() took */
 204         put_device(&pb->mii_bus->dev);
 205 }
 206 EXPORT_SYMBOL_GPL(mdio_mux_uninit);
 207
 208 MODULE_DESCRIPTION(DRV_DESCRIPTION);
 209 MODULE_VERSION(DRV_VERSION);
 210 MODULE_AUTHOR("David Daney");
 211 MODULE_LICENSE("GPL");