1 /* 2 * MDIO bus driver for the Xilinx Axi Ethernet device 3 * 4 * Copyright (c) 2009 Secret Lab Technologies, Ltd. 5 * Copyright (c) 2010 - 2011 Michal Simek <monstr@monstr.eu> 6 * Copyright (c) 2010 - 2011 PetaLogix 7 * Copyright (c) 2010 - 2012 Xilinx, Inc. All rights reserved. 8 */ 9 10 #include <linux/of_address.h> 11 #include <linux/of_mdio.h> 12 #include <linux/jiffies.h> 13 14 #include "xilinx_axienet.h" 15 16 #define MAX_MDIO_FREQ 2500000 /* 2.5 MHz */ 17 #define DEFAULT_CLOCK_DIVISOR XAE_MDIO_DIV_DFT 18 19 /* Wait till MDIO interface is ready to accept a new transaction.*/ 20 int axienet_mdio_wait_until_ready(struct axienet_local *lp) 21 { 22 unsigned long end = jiffies + 2; 23 while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) & 24 XAE_MDIO_MCR_READY_MASK)) { 25 if (time_before_eq(end, jiffies)) { 26 WARN_ON(1); 27 return -ETIMEDOUT; 28 } 29 udelay(1); 30 } 31 return 0; 32 } 33 34 /** 35 * axienet_mdio_read - MDIO interface read function 36 * @bus: Pointer to mii bus structure 37 * @phy_id: Address of the PHY device 38 * @reg: PHY register to read 39 * 40 * Return: The register contents on success, -ETIMEDOUT on a timeout 41 * 42 * Reads the contents of the requested register from the requested PHY 43 * address by first writing the details into MCR register. After a while 44 * the register MRD is read to obtain the PHY register content. 45 */ 46 static int axienet_mdio_read(struct mii_bus *bus, int phy_id, int reg) 47 { 48 u32 rc; 49 int ret; 50 struct axienet_local *lp = bus->priv; 51 52 ret = axienet_mdio_wait_until_ready(lp); 53 if (ret < 0) 54 return ret; 55 56 axienet_iow(lp, XAE_MDIO_MCR_OFFSET, 57 (((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) & 58 XAE_MDIO_MCR_PHYAD_MASK) | 59 ((reg << XAE_MDIO_MCR_REGAD_SHIFT) & 60 XAE_MDIO_MCR_REGAD_MASK) | 61 XAE_MDIO_MCR_INITIATE_MASK | 62 XAE_MDIO_MCR_OP_READ_MASK)); 63 64 ret = axienet_mdio_wait_until_ready(lp); 65 if (ret < 0) 66 return ret; 67 68 rc = axienet_ior(lp, XAE_MDIO_MRD_OFFSET) & 0x0000FFFF; 69 70 dev_dbg(lp->dev, "axienet_mdio_read(phy_id=%i, reg=%x) == %x\n", 71 phy_id, reg, rc); 72 73 return rc; 74 } 75 76 /** 77 * axienet_mdio_write - MDIO interface write function 78 * @bus: Pointer to mii bus structure 79 * @phy_id: Address of the PHY device 80 * @reg: PHY register to write to 81 * @val: Value to be written into the register 82 * 83 * Return: 0 on success, -ETIMEDOUT on a timeout 84 * 85 * Writes the value to the requested register by first writing the value 86 * into MWD register. The the MCR register is then appropriately setup 87 * to finish the write operation. 88 */ 89 static int axienet_mdio_write(struct mii_bus *bus, int phy_id, int reg, 90 u16 val) 91 { 92 int ret; 93 struct axienet_local *lp = bus->priv; 94 95 dev_dbg(lp->dev, "axienet_mdio_write(phy_id=%i, reg=%x, val=%x)\n", 96 phy_id, reg, val); 97 98 ret = axienet_mdio_wait_until_ready(lp); 99 if (ret < 0) 100 return ret; 101 102 axienet_iow(lp, XAE_MDIO_MWD_OFFSET, (u32) val); 103 axienet_iow(lp, XAE_MDIO_MCR_OFFSET, 104 (((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) & 105 XAE_MDIO_MCR_PHYAD_MASK) | 106 ((reg << XAE_MDIO_MCR_REGAD_SHIFT) & 107 XAE_MDIO_MCR_REGAD_MASK) | 108 XAE_MDIO_MCR_INITIATE_MASK | 109 XAE_MDIO_MCR_OP_WRITE_MASK)); 110 111 ret = axienet_mdio_wait_until_ready(lp); 112 if (ret < 0) 113 return ret; 114 return 0; 115 } 116 117 /** 118 * axienet_mdio_setup - MDIO setup function 119 * @lp: Pointer to axienet local data structure. 120 * @np: Pointer to device node 121 * 122 * Return: 0 on success, -ETIMEDOUT on a timeout, -ENOMEM when 123 * mdiobus_alloc (to allocate memory for mii bus structure) fails. 124 * 125 * Sets up the MDIO interface by initializing the MDIO clock and enabling the 126 * MDIO interface in hardware. Register the MDIO interface. 127 **/ 128 int axienet_mdio_setup(struct axienet_local *lp, struct device_node *np) 129 { 130 int ret; 131 u32 clk_div, host_clock; 132 struct mii_bus *bus; 133 struct resource res; 134 struct device_node *np1; 135 136 /* clk_div can be calculated by deriving it from the equation: 137 * fMDIO = fHOST / ((1 + clk_div) * 2) 138 * 139 * Where fMDIO <= 2500000, so we get: 140 * fHOST / ((1 + clk_div) * 2) <= 2500000 141 * 142 * Then we get: 143 * 1 / ((1 + clk_div) * 2) <= (2500000 / fHOST) 144 * 145 * Then we get: 146 * 1 / (1 + clk_div) <= ((2500000 * 2) / fHOST) 147 * 148 * Then we get: 149 * 1 / (1 + clk_div) <= (5000000 / fHOST) 150 * 151 * So: 152 * (1 + clk_div) >= (fHOST / 5000000) 153 * 154 * And finally: 155 * clk_div >= (fHOST / 5000000) - 1 156 * 157 * fHOST can be read from the flattened device tree as property 158 * "clock-frequency" from the CPU 159 */ 160 161 np1 = of_find_node_by_name(NULL, "cpu"); 162 if (!np1) { 163 netdev_warn(lp->ndev, "Could not find CPU device node.\n"); 164 netdev_warn(lp->ndev, 165 "Setting MDIO clock divisor to default %d\n", 166 DEFAULT_CLOCK_DIVISOR); 167 clk_div = DEFAULT_CLOCK_DIVISOR; 168 goto issue; 169 } 170 if (of_property_read_u32(np1, "clock-frequency", &host_clock)) { 171 netdev_warn(lp->ndev, "clock-frequency property not found.\n"); 172 netdev_warn(lp->ndev, 173 "Setting MDIO clock divisor to default %d\n", 174 DEFAULT_CLOCK_DIVISOR); 175 clk_div = DEFAULT_CLOCK_DIVISOR; 176 of_node_put(np1); 177 goto issue; 178 } 179 180 clk_div = (host_clock / (MAX_MDIO_FREQ * 2)) - 1; 181 /* If there is any remainder from the division of 182 * fHOST / (MAX_MDIO_FREQ * 2), then we need to add 183 * 1 to the clock divisor or we will surely be above 2.5 MHz 184 */ 185 if (host_clock % (MAX_MDIO_FREQ * 2)) 186 clk_div++; 187 188 netdev_dbg(lp->ndev, 189 "Setting MDIO clock divisor to %u/%u Hz host clock.\n", 190 clk_div, host_clock); 191 192 of_node_put(np1); 193 issue: 194 axienet_iow(lp, XAE_MDIO_MC_OFFSET, 195 (((u32) clk_div) | XAE_MDIO_MC_MDIOEN_MASK)); 196 197 ret = axienet_mdio_wait_until_ready(lp); 198 if (ret < 0) 199 return ret; 200 201 bus = mdiobus_alloc(); 202 if (!bus) 203 return -ENOMEM; 204 205 np1 = of_get_parent(lp->phy_node); 206 of_address_to_resource(np1, 0, &res); 207 snprintf(bus->id, MII_BUS_ID_SIZE, "%.8llx", 208 (unsigned long long) res.start); 209 210 bus->priv = lp; 211 bus->name = "Xilinx Axi Ethernet MDIO"; 212 bus->read = axienet_mdio_read; 213 bus->write = axienet_mdio_write; 214 bus->parent = lp->dev; 215 lp->mii_bus = bus; 216 217 ret = of_mdiobus_register(bus, np1); 218 if (ret) { 219 mdiobus_free(bus); 220 return ret; 221 } 222 return 0; 223 } 224 225 /** 226 * axienet_mdio_teardown - MDIO remove function 227 * @lp: Pointer to axienet local data structure. 228 * 229 * Unregisters the MDIO and frees any associate memory for mii bus. 230 */ 231 void axienet_mdio_teardown(struct axienet_local *lp) 232 { 233 mdiobus_unregister(lp->mii_bus); 234 mdiobus_free(lp->mii_bus); 235 lp->mii_bus = NULL; 236 } 237