drivers/net/ethernet/arc/emac_mdio.c

   1 /*
   2  * Copyright (C) 2004-2013 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * MDIO implementation for ARC EMAC
   5  */
   6
   7 #include <linux/delay.h>
   8 #include <linux/of_mdio.h>
   9 #include <linux/platform_device.h>
  10 #include <linux/gpio/consumer.h>
  11
  12 #include "emac.h"
  13
  14 /* Number of seconds we wait for "MDIO complete" flag to appear */
  15 #define ARC_MDIO_COMPLETE_POLL_COUNT    1
  16
  17 /**
  18  * arc_mdio_complete_wait - Waits until MDIO transaction is completed.
  19  * @priv:       Pointer to ARC EMAC private data structure.
  20  *
  21  * returns:     0 on success, -ETIMEDOUT on a timeout.
  22  */
  23 static int arc_mdio_complete_wait(struct arc_emac_priv *priv)
  24 {
  25         unsigned int i;
  26
  27         for (i = 0; i < ARC_MDIO_COMPLETE_POLL_COUNT * 40; i++) {
  28                 unsigned int status = arc_reg_get(priv, R_STATUS);
  29
  30                 status &= MDIO_MASK;
  31
  32                 if (status) {
  33                         /* Reset "MDIO complete" flag */
  34                         arc_reg_set(priv, R_STATUS, status);
  35                         return 0;
  36                 }
  37
  38                 msleep(25);
  39         }
  40
  41         return -ETIMEDOUT;
  42 }
  43
  44 /**
  45  * arc_mdio_read - MDIO interface read function.
  46  * @bus:        Pointer to MII bus structure.
  47  * @phy_addr:   Address of the PHY device.
  48  * @reg_num:    PHY register to read.
  49  *
  50  * returns:     The register contents on success, -ETIMEDOUT on a timeout.
  51  *
  52  * Reads the contents of the requested register from the requested PHY
  53  * address.
  54  */
  55 static int arc_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
  56 {
  57         struct arc_emac_priv *priv = bus->priv;
  58         unsigned int value;
  59         int error;
  60
  61         arc_reg_set(priv, R_MDIO,
  62                     0x60020000 | (phy_addr << 23) | (reg_num << 18));
  63
  64         error = arc_mdio_complete_wait(priv);
  65         if (error < 0)
  66                 return error;
  67
  68         value = arc_reg_get(priv, R_MDIO) & 0xffff;
  69
  70         dev_dbg(priv->dev, "arc_mdio_read(phy_addr=%i, reg_num=%x) = %x\n",
  71                 phy_addr, reg_num, value);
  72
  73         return value;
  74 }
  75
  76 /**
  77  * arc_mdio_write - MDIO interface write function.
  78  * @bus:        Pointer to MII bus structure.
  79  * @phy_addr:   Address of the PHY device.
  80  * @reg_num:    PHY register to write to.
  81  * @value:      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.
  86  */
  87 static int arc_mdio_write(struct mii_bus *bus, int phy_addr,
  88                           int reg_num, u16 value)
  89 {
  90         struct arc_emac_priv *priv = bus->priv;
  91
  92         dev_dbg(priv->dev,
  93                 "arc_mdio_write(phy_addr=%i, reg_num=%x, value=%x)\n",
  94                 phy_addr, reg_num, value);
  95
  96         arc_reg_set(priv, R_MDIO,
  97                     0x50020000 | (phy_addr << 23) | (reg_num << 18) | value);
  98
  99         return arc_mdio_complete_wait(priv);
 100 }
 101
 102 /**
 103  * arc_mdio_reset
 104  * @bus: points to the mii_bus structure
 105  * Description: reset the MII bus
 106  */
 107 static int arc_mdio_reset(struct mii_bus *bus)
 108 {
 109         struct arc_emac_priv *priv = bus->priv;
 110         struct arc_emac_mdio_bus_data *data = &priv->bus_data;
 111
 112         if (data->reset_gpio) {
 113                 gpiod_set_value_cansleep(data->reset_gpio, 1);
 114                 msleep(data->msec);
 115                 gpiod_set_value_cansleep(data->reset_gpio, 0);
 116         }
 117
 118         return 0;
 119 }
 120
 121 /**
 122  * arc_mdio_probe - MDIO probe function.
 123  * @priv:       Pointer to ARC EMAC private data structure.
 124  *
 125  * returns:     0 on success, -ENOMEM when mdiobus_alloc
 126  * (to allocate memory for MII bus structure) fails.
 127  *
 128  * Sets up and registers the MDIO interface.
 129  */
 130 int arc_mdio_probe(struct arc_emac_priv *priv)
 131 {
 132         struct arc_emac_mdio_bus_data *data = &priv->bus_data;
 133         struct device_node *np = priv->dev->of_node;
 134         struct mii_bus *bus;
 135         int error;
 136
 137         bus = mdiobus_alloc();
 138         if (!bus)
 139                 return -ENOMEM;
 140
 141         priv->bus = bus;
 142         bus->priv = priv;
 143         bus->parent = priv->dev;
 144         bus->name = "Synopsys MII Bus";
 145         bus->read = &arc_mdio_read;
 146         bus->write = &arc_mdio_write;
 147         bus->reset = &arc_mdio_reset;
 148
 149         /* optional reset-related properties */
 150         data->reset_gpio = devm_gpiod_get_optional(priv->dev, "phy-reset",
 151                                                    GPIOD_OUT_LOW);
 152         if (IS_ERR(data->reset_gpio)) {
 153                 error = PTR_ERR(data->reset_gpio);
 154                 dev_err(priv->dev, "Failed to request gpio: %d\n", error);
 155                 return error;
 156         }
 157
 158         of_property_read_u32(np, "phy-reset-duration", &data->msec);
 159         /* A sane reset duration should not be longer than 1s */
 160         if (data->msec > 1000)
 161                 data->msec = 1;
 162
 163         snprintf(bus->id, MII_BUS_ID_SIZE, "%s", bus->name);
 164
 165         error = of_mdiobus_register(bus, priv->dev->of_node);
 166         if (error) {
 167                 dev_err(priv->dev, "cannot register MDIO bus %s\n", bus->name);
 168                 mdiobus_free(bus);
 169                 return error;
 170         }
 171
 172         return 0;
 173 }
 174
 175 /**
 176  * arc_mdio_remove - MDIO remove function.
 177  * @priv:       Pointer to ARC EMAC private data structure.
 178  *
 179  * Unregisters the MDIO and frees any associate memory for MII bus.
 180  */
 181 int arc_mdio_remove(struct arc_emac_priv *priv)
 182 {
 183         mdiobus_unregister(priv->bus);
 184         mdiobus_free(priv->bus);
 185         priv->bus = NULL;
 186
 187         return 0;
 188 }