1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2011, 2012 Cavium, Inc. 4 */ 5 6 #include <linux/platform_device.h> 7 #include <linux/mdio-mux.h> 8 #include <linux/of_mdio.h> 9 #include <linux/device.h> 10 #include <linux/module.h> 11 #include <linux/phy.h> 12 13 #define DRV_DESCRIPTION "MDIO bus multiplexer driver" 14 15 struct mdio_mux_child_bus; 16 17 struct mdio_mux_parent_bus { 18 struct mii_bus *mii_bus; 19 int current_child; 20 int parent_id; 21 void *switch_data; 22 int (*switch_fn)(int current_child, int desired_child, void *data); 23 24 /* List of our children linked through their next fields. */ 25 struct mdio_mux_child_bus *children; 26 }; 27 28 struct mdio_mux_child_bus { 29 struct mii_bus *mii_bus; 30 struct mdio_mux_parent_bus *parent; 31 struct mdio_mux_child_bus *next; 32 int bus_number; 33 }; 34 35 /* 36 * The parent bus' lock is used to order access to the switch_fn. 37 */ 38 static int mdio_mux_read(struct mii_bus *bus, int phy_id, int regnum) 39 { 40 struct mdio_mux_child_bus *cb = bus->priv; 41 struct mdio_mux_parent_bus *pb = cb->parent; 42 int r; 43 44 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX); 45 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data); 46 if (r) 47 goto out; 48 49 pb->current_child = cb->bus_number; 50 51 r = pb->mii_bus->read(pb->mii_bus, phy_id, regnum); 52 out: 53 mutex_unlock(&pb->mii_bus->mdio_lock); 54 55 return r; 56 } 57 58 /* 59 * The parent bus' lock is used to order access to the switch_fn. 60 */ 61 static int mdio_mux_write(struct mii_bus *bus, int phy_id, 62 int regnum, u16 val) 63 { 64 struct mdio_mux_child_bus *cb = bus->priv; 65 struct mdio_mux_parent_bus *pb = cb->parent; 66 67 int r; 68 69 mutex_lock_nested(&pb->mii_bus->mdio_lock, MDIO_MUTEX_MUX); 70 r = pb->switch_fn(pb->current_child, cb->bus_number, pb->switch_data); 71 if (r) 72 goto out; 73 74 pb->current_child = cb->bus_number; 75 76 r = pb->mii_bus->write(pb->mii_bus, phy_id, regnum, val); 77 out: 78 mutex_unlock(&pb->mii_bus->mdio_lock); 79 80 return r; 81 } 82 83 static int parent_count; 84 85 int mdio_mux_init(struct device *dev, 86 struct device_node *mux_node, 87 int (*switch_fn)(int cur, int desired, void *data), 88 void **mux_handle, 89 void *data, 90 struct mii_bus *mux_bus) 91 { 92 struct device_node *parent_bus_node; 93 struct device_node *child_bus_node; 94 int r, ret_val; 95 struct mii_bus *parent_bus; 96 struct mdio_mux_parent_bus *pb; 97 struct mdio_mux_child_bus *cb; 98 99 if (!mux_node) 100 return -ENODEV; 101 102 if (!mux_bus) { 103 parent_bus_node = of_parse_phandle(mux_node, 104 "mdio-parent-bus", 0); 105 106 if (!parent_bus_node) 107 return -ENODEV; 108 109 parent_bus = of_mdio_find_bus(parent_bus_node); 110 if (!parent_bus) { 111 ret_val = -EPROBE_DEFER; 112 goto err_parent_bus; 113 } 114 } else { 115 parent_bus_node = NULL; 116 parent_bus = mux_bus; 117 get_device(&parent_bus->dev); 118 } 119 120 pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL); 121 if (!pb) { 122 ret_val = -ENOMEM; 123 goto err_pb_kz; 124 } 125 126 pb->switch_data = data; 127 pb->switch_fn = switch_fn; 128 pb->current_child = -1; 129 pb->parent_id = parent_count++; 130 pb->mii_bus = parent_bus; 131 132 ret_val = -ENODEV; 133 for_each_available_child_of_node(mux_node, child_bus_node) { 134 int v; 135 136 r = of_property_read_u32(child_bus_node, "reg", &v); 137 if (r) { 138 dev_err(dev, 139 "Error: Failed to find reg for child %pOF\n", 140 child_bus_node); 141 continue; 142 } 143 144 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL); 145 if (!cb) { 146 ret_val = -ENOMEM; 147 continue; 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 devm_kfree(dev, cb); 156 continue; 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 dev_err(dev, 169 "Error: Failed to register MDIO bus for child %pOF\n", 170 child_bus_node); 171 mdiobus_free(cb->mii_bus); 172 devm_kfree(dev, cb); 173 } else { 174 cb->next = pb->children; 175 pb->children = cb; 176 } 177 } 178 if (pb->children) { 179 *mux_handle = pb; 180 return 0; 181 } 182 183 dev_err(dev, "Error: No acceptable child buses found\n"); 184 devm_kfree(dev, pb); 185 err_pb_kz: 186 put_device(&parent_bus->dev); 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 put_device(&pb->mii_bus->dev); 205 } 206 EXPORT_SYMBOL_GPL(mdio_mux_uninit); 207 208 MODULE_DESCRIPTION(DRV_DESCRIPTION); 209 MODULE_AUTHOR("David Daney"); 210 MODULE_LICENSE("GPL v2"); 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