1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2011, 2012 Cavium, Inc. 4 */ 5 6 #include <linux/device.h> 7 #include <linux/mdio-mux.h> 8 #include <linux/module.h> 9 #include <linux/of_mdio.h> 10 #include <linux/phy.h> 11 #include <linux/platform_device.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 static void mdio_mux_uninit_children(struct mdio_mux_parent_bus *pb) 86 { 87 struct mdio_mux_child_bus *cb = pb->children; 88 89 while (cb) { 90 mdiobus_unregister(cb->mii_bus); 91 mdiobus_free(cb->mii_bus); 92 cb = cb->next; 93 } 94 } 95 96 int mdio_mux_init(struct device *dev, 97 struct device_node *mux_node, 98 int (*switch_fn)(int cur, int desired, void *data), 99 void **mux_handle, 100 void *data, 101 struct mii_bus *mux_bus) 102 { 103 struct device_node *parent_bus_node; 104 struct device_node *child_bus_node; 105 int r, ret_val; 106 struct mii_bus *parent_bus; 107 struct mdio_mux_parent_bus *pb; 108 struct mdio_mux_child_bus *cb; 109 110 if (!mux_node) 111 return -ENODEV; 112 113 if (!mux_bus) { 114 parent_bus_node = of_parse_phandle(mux_node, 115 "mdio-parent-bus", 0); 116 117 if (!parent_bus_node) 118 return -ENODEV; 119 120 parent_bus = of_mdio_find_bus(parent_bus_node); 121 if (!parent_bus) { 122 ret_val = -EPROBE_DEFER; 123 goto err_parent_bus; 124 } 125 } else { 126 parent_bus_node = NULL; 127 parent_bus = mux_bus; 128 get_device(&parent_bus->dev); 129 } 130 131 pb = devm_kzalloc(dev, sizeof(*pb), GFP_KERNEL); 132 if (!pb) { 133 ret_val = -ENOMEM; 134 goto err_pb_kz; 135 } 136 137 pb->switch_data = data; 138 pb->switch_fn = switch_fn; 139 pb->current_child = -1; 140 pb->parent_id = parent_count++; 141 pb->mii_bus = parent_bus; 142 143 ret_val = -ENODEV; 144 for_each_available_child_of_node(mux_node, child_bus_node) { 145 int v; 146 147 r = of_property_read_u32(child_bus_node, "reg", &v); 148 if (r) { 149 dev_err(dev, 150 "Error: Failed to find reg for child %pOF\n", 151 child_bus_node); 152 continue; 153 } 154 155 cb = devm_kzalloc(dev, sizeof(*cb), GFP_KERNEL); 156 if (!cb) { 157 ret_val = -ENOMEM; 158 goto err_loop; 159 } 160 cb->bus_number = v; 161 cb->parent = pb; 162 163 cb->mii_bus = mdiobus_alloc(); 164 if (!cb->mii_bus) { 165 ret_val = -ENOMEM; 166 goto err_loop; 167 } 168 cb->mii_bus->priv = cb; 169 170 cb->mii_bus->name = "mdio_mux"; 171 snprintf(cb->mii_bus->id, MII_BUS_ID_SIZE, "%s-%x.%x", 172 cb->mii_bus->name, pb->parent_id, v); 173 cb->mii_bus->parent = dev; 174 cb->mii_bus->read = mdio_mux_read; 175 cb->mii_bus->write = mdio_mux_write; 176 r = of_mdiobus_register(cb->mii_bus, child_bus_node); 177 if (r) { 178 mdiobus_free(cb->mii_bus); 179 if (r == -EPROBE_DEFER) { 180 ret_val = r; 181 goto err_loop; 182 } 183 devm_kfree(dev, cb); 184 dev_err(dev, 185 "Error: Failed to register MDIO bus for child %pOF\n", 186 child_bus_node); 187 } else { 188 cb->next = pb->children; 189 pb->children = cb; 190 } 191 } 192 if (pb->children) { 193 *mux_handle = pb; 194 return 0; 195 } 196 197 dev_err(dev, "Error: No acceptable child buses found\n"); 198 199 err_loop: 200 mdio_mux_uninit_children(pb); 201 of_node_put(child_bus_node); 202 err_pb_kz: 203 put_device(&parent_bus->dev); 204 err_parent_bus: 205 of_node_put(parent_bus_node); 206 return ret_val; 207 } 208 EXPORT_SYMBOL_GPL(mdio_mux_init); 209 210 void mdio_mux_uninit(void *mux_handle) 211 { 212 struct mdio_mux_parent_bus *pb = mux_handle; 213 214 mdio_mux_uninit_children(pb); 215 put_device(&pb->mii_bus->dev); 216 } 217 EXPORT_SYMBOL_GPL(mdio_mux_uninit); 218 219 MODULE_DESCRIPTION(DRV_DESCRIPTION); 220 MODULE_AUTHOR("David Daney"); 221 MODULE_LICENSE("GPL v2"); 222