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 long end = jiffies + 2; 23 while (!(axienet_ior(lp, XAE_MDIO_MCR_OFFSET) & 24 XAE_MDIO_MCR_READY_MASK)) { 25 if (end - jiffies <= 0) { 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 * returns: 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 * returns: 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 * returns: 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 u32 *property_p; 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 printk(KERN_WARNING "%s(): Could not find CPU device node.", 165 __func__); 166 printk(KERN_WARNING "Setting MDIO clock divisor to " 167 "default %d\n", DEFAULT_CLOCK_DIVISOR); 168 clk_div = DEFAULT_CLOCK_DIVISOR; 169 goto issue; 170 } 171 property_p = (u32 *) of_get_property(np1, "clock-frequency", NULL); 172 if (!property_p) { 173 printk(KERN_WARNING "%s(): Could not find CPU property: " 174 "clock-frequency.", __func__); 175 printk(KERN_WARNING "Setting MDIO clock divisor to " 176 "default %d\n", DEFAULT_CLOCK_DIVISOR); 177 clk_div = DEFAULT_CLOCK_DIVISOR; 178 of_node_put(np1); 179 goto issue; 180 } 181 182 host_clock = be32_to_cpup(property_p); 183 clk_div = (host_clock / (MAX_MDIO_FREQ * 2)) - 1; 184 /* If there is any remainder from the division of 185 * fHOST / (MAX_MDIO_FREQ * 2), then we need to add 186 * 1 to the clock divisor or we will surely be above 2.5 MHz */ 187 if (host_clock % (MAX_MDIO_FREQ * 2)) 188 clk_div++; 189 190 printk(KERN_DEBUG "%s(): Setting MDIO clock divisor to %u based " 191 "on %u Hz host clock.\n", __func__, 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 bus->irq = lp->mdio_irqs; /* preallocated IRQ table */ 217 lp->mii_bus = bus; 218 219 ret = of_mdiobus_register(bus, np1); 220 if (ret) { 221 mdiobus_free(bus); 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 kfree(lp->mii_bus->irq); 237 mdiobus_free(lp->mii_bus); 238 lp->mii_bus = NULL; 239 } 240