drivers/net/ethernet/xilinx/xilinx_axienet_mdio.c

   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 }