1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * MDIO bus driver for the Xilinx Axi Ethernet device 4 * 5 * Copyright (c) 2009 Secret Lab Technologies, Ltd. 6 * Copyright (c) 2010 - 2011 Michal Simek <monstr@monstr.eu> 7 * Copyright (c) 2010 - 2011 PetaLogix 8 * Copyright (c) 2010 - 2012 Xilinx, Inc. All rights reserved. 9 */ 10 11 #include <linux/of_address.h> 12 #include <linux/of_mdio.h> 13 #include <linux/jiffies.h> 14 15 #include "xilinx_axienet.h" 16 17 #define MAX_MDIO_FREQ 2500000 /* 2.5 MHz */ 18 #define DEFAULT_CLOCK_DIVISOR XAE_MDIO_DIV_DFT 19 20 /* Wait till MDIO interface is ready to accept a new transaction.*/ 21 int axienet_mdio_wait_until_ready(struct axienet_local *lp) 22 { 23 unsigned long end = jiffies + 2; 24 while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) & 25 XAE_MDIO_MCR_READY_MASK)) { 26 if (time_before_eq(end, jiffies)) { 27 WARN_ON(1); 28 return -ETIMEDOUT; 29 } 30 udelay(1); 31 } 32 return 0; 33 } 34 35 /** 36 * axienet_mdio_read - MDIO interface read function 37 * @bus: Pointer to mii bus structure 38 * @phy_id: Address of the PHY device 39 * @reg: PHY register to read 40 * 41 * Return: The register contents on success, -ETIMEDOUT on a timeout 42 * 43 * Reads the contents of the requested register from the requested PHY 44 * address by first writing the details into MCR register. After a while 45 * the register MRD is read to obtain the PHY register content. 46 */ 47 static int axienet_mdio_read(struct mii_bus *bus, int phy_id, int reg) 48 { 49 u32 rc; 50 int ret; 51 struct axienet_local *lp = bus->priv; 52 53 ret = axienet_mdio_wait_until_ready(lp); 54 if (ret < 0) 55 return ret; 56 57 axienet_iow(lp, XAE_MDIO_MCR_OFFSET, 58 (((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) & 59 XAE_MDIO_MCR_PHYAD_MASK) | 60 ((reg << XAE_MDIO_MCR_REGAD_SHIFT) & 61 XAE_MDIO_MCR_REGAD_MASK) | 62 XAE_MDIO_MCR_INITIATE_MASK | 63 XAE_MDIO_MCR_OP_READ_MASK)); 64 65 ret = axienet_mdio_wait_until_ready(lp); 66 if (ret < 0) 67 return ret; 68 69 rc = axienet_ior(lp, XAE_MDIO_MRD_OFFSET) & 0x0000FFFF; 70 71 dev_dbg(lp->dev, "axienet_mdio_read(phy_id=%i, reg=%x) == %x\n", 72 phy_id, reg, rc); 73 74 return rc; 75 } 76 77 /** 78 * axienet_mdio_write - MDIO interface write function 79 * @bus: Pointer to mii bus structure 80 * @phy_id: Address of the PHY device 81 * @reg: PHY register to write to 82 * @val: Value to be written into the register 83 * 84 * Return: 0 on success, -ETIMEDOUT on a timeout 85 * 86 * Writes the value to the requested register by first writing the value 87 * into MWD register. The the MCR register is then appropriately setup 88 * to finish the write operation. 89 */ 90 static int axienet_mdio_write(struct mii_bus *bus, int phy_id, int reg, 91 u16 val) 92 { 93 int ret; 94 struct axienet_local *lp = bus->priv; 95 96 dev_dbg(lp->dev, "axienet_mdio_write(phy_id=%i, reg=%x, val=%x)\n", 97 phy_id, reg, val); 98 99 ret = axienet_mdio_wait_until_ready(lp); 100 if (ret < 0) 101 return ret; 102 103 axienet_iow(lp, XAE_MDIO_MWD_OFFSET, (u32) val); 104 axienet_iow(lp, XAE_MDIO_MCR_OFFSET, 105 (((phy_id << XAE_MDIO_MCR_PHYAD_SHIFT) & 106 XAE_MDIO_MCR_PHYAD_MASK) | 107 ((reg << XAE_MDIO_MCR_REGAD_SHIFT) & 108 XAE_MDIO_MCR_REGAD_MASK) | 109 XAE_MDIO_MCR_INITIATE_MASK | 110 XAE_MDIO_MCR_OP_WRITE_MASK)); 111 112 ret = axienet_mdio_wait_until_ready(lp); 113 if (ret < 0) 114 return ret; 115 return 0; 116 } 117 118 /** 119 * axienet_mdio_setup - MDIO setup function 120 * @lp: Pointer to axienet local data structure. 121 * @np: Pointer to device node 122 * 123 * Return: 0 on success, -ETIMEDOUT on a timeout, -ENOMEM when 124 * mdiobus_alloc (to allocate memory for mii bus structure) fails. 125 * 126 * Sets up the MDIO interface by initializing the MDIO clock and enabling the 127 * MDIO interface in hardware. Register the MDIO interface. 128 **/ 129 int axienet_mdio_setup(struct axienet_local *lp, struct device_node *np) 130 { 131 int ret; 132 u32 clk_div, host_clock; 133 struct mii_bus *bus; 134 struct resource res; 135 struct device_node *np1; 136 137 /* clk_div can be calculated by deriving it from the equation: 138 * fMDIO = fHOST / ((1 + clk_div) * 2) 139 * 140 * Where fMDIO <= 2500000, so we get: 141 * fHOST / ((1 + clk_div) * 2) <= 2500000 142 * 143 * Then we get: 144 * 1 / ((1 + clk_div) * 2) <= (2500000 / fHOST) 145 * 146 * Then we get: 147 * 1 / (1 + clk_div) <= ((2500000 * 2) / fHOST) 148 * 149 * Then we get: 150 * 1 / (1 + clk_div) <= (5000000 / fHOST) 151 * 152 * So: 153 * (1 + clk_div) >= (fHOST / 5000000) 154 * 155 * And finally: 156 * clk_div >= (fHOST / 5000000) - 1 157 * 158 * fHOST can be read from the flattened device tree as property 159 * "clock-frequency" from the CPU 160 */ 161 162 np1 = of_find_node_by_name(NULL, "cpu"); 163 if (!np1) { 164 netdev_warn(lp->ndev, "Could not find CPU device node.\n"); 165 netdev_warn(lp->ndev, 166 "Setting MDIO clock divisor to default %d\n", 167 DEFAULT_CLOCK_DIVISOR); 168 clk_div = DEFAULT_CLOCK_DIVISOR; 169 goto issue; 170 } 171 if (of_property_read_u32(np1, "clock-frequency", &host_clock)) { 172 netdev_warn(lp->ndev, "clock-frequency property not found.\n"); 173 netdev_warn(lp->ndev, 174 "Setting MDIO clock divisor to default %d\n", 175 DEFAULT_CLOCK_DIVISOR); 176 clk_div = DEFAULT_CLOCK_DIVISOR; 177 of_node_put(np1); 178 goto issue; 179 } 180 181 clk_div = (host_clock / (MAX_MDIO_FREQ * 2)) - 1; 182 /* If there is any remainder from the division of 183 * fHOST / (MAX_MDIO_FREQ * 2), then we need to add 184 * 1 to the clock divisor or we will surely be above 2.5 MHz 185 */ 186 if (host_clock % (MAX_MDIO_FREQ * 2)) 187 clk_div++; 188 189 netdev_dbg(lp->ndev, 190 "Setting MDIO clock divisor to %u/%u Hz host clock.\n", 191 clk_div, host_clock); 192 193 of_node_put(np1); 194 issue: 195 axienet_iow(lp, XAE_MDIO_MC_OFFSET, 196 (((u32) clk_div) | XAE_MDIO_MC_MDIOEN_MASK)); 197 198 ret = axienet_mdio_wait_until_ready(lp); 199 if (ret < 0) 200 return ret; 201 202 bus = mdiobus_alloc(); 203 if (!bus) 204 return -ENOMEM; 205 206 np1 = of_get_parent(lp->phy_node); 207 of_address_to_resource(np1, 0, &res); 208 snprintf(bus->id, MII_BUS_ID_SIZE, "%.8llx", 209 (unsigned long long) res.start); 210 211 bus->priv = lp; 212 bus->name = "Xilinx Axi Ethernet MDIO"; 213 bus->read = axienet_mdio_read; 214 bus->write = axienet_mdio_write; 215 bus->parent = lp->dev; 216 lp->mii_bus = bus; 217 218 ret = of_mdiobus_register(bus, np1); 219 if (ret) { 220 mdiobus_free(bus); 221 lp->mii_bus = NULL; 222 return ret; 223 } 224 return 0; 225 } 226 227 /** 228 * axienet_mdio_teardown - MDIO remove function 229 * @lp: Pointer to axienet local data structure. 230 * 231 * Unregisters the MDIO and frees any associate memory for mii bus. 232 */ 233 void axienet_mdio_teardown(struct axienet_local *lp) 234 { 235 mdiobus_unregister(lp->mii_bus); 236 mdiobus_free(lp->mii_bus); 237 lp->mii_bus = NULL; 238 } 239