* MDIO I2C bridge
*
* Copyright (C) 2015-2016 Russell King
+ * Copyright (C) 2021 Marek Behun
*
* Network PHYs can appear on I2C buses when they are part of SFP module.
* This driver exposes these PHYs to the networking PHY code, allowing
#include <linux/i2c.h>
#include <linux/mdio/mdio-i2c.h>
#include <linux/phy.h>
+#include <linux/sfp.h>
/*
* I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is
return phy_id + 0x40;
}
-static int i2c_mii_read(struct mii_bus *bus, int phy_id, int reg)
+static int i2c_mii_read_default(struct mii_bus *bus, int phy_id, int reg)
{
struct i2c_adapter *i2c = bus->priv;
struct i2c_msg msgs[2];
return data[0] << 8 | data[1];
}
-static int i2c_mii_write(struct mii_bus *bus, int phy_id, int reg, u16 val)
+static int i2c_mii_write_default(struct mii_bus *bus, int phy_id, int reg,
+ u16 val)
{
struct i2c_adapter *i2c = bus->priv;
struct i2c_msg msg;
return ret < 0 ? ret : 0;
}
-struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c)
+/* RollBall SFPs do not access internal PHY via I2C address 0x56, but
+ * instead via address 0x51, when SFP page is set to 0x03 and password to
+ * 0xffffffff.
+ *
+ * address size contents description
+ * ------- ---- -------- -----------
+ * 0x80 1 CMD 0x01/0x02/0x04 for write/read/done
+ * 0x81 1 DEV Clause 45 device
+ * 0x82 2 REG Clause 45 register
+ * 0x84 2 VAL Register value
+ */
+#define ROLLBALL_PHY_I2C_ADDR 0x51
+
+#define ROLLBALL_PASSWORD (SFP_VSL + 3)
+
+#define ROLLBALL_CMD_ADDR 0x80
+#define ROLLBALL_DATA_ADDR 0x81
+
+#define ROLLBALL_CMD_WRITE 0x01
+#define ROLLBALL_CMD_READ 0x02
+#define ROLLBALL_CMD_DONE 0x04
+
+#define SFP_PAGE_ROLLBALL_MDIO 3
+
+static int __i2c_transfer_err(struct i2c_adapter *i2c, struct i2c_msg *msgs,
+ int num)
+{
+ int ret;
+
+ ret = __i2c_transfer(i2c, msgs, num);
+ if (ret < 0)
+ return ret;
+ else if (ret != num)
+ return -EIO;
+ else
+ return 0;
+}
+
+static int __i2c_rollball_get_page(struct i2c_adapter *i2c, int bus_addr,
+ u8 *page)
+{
+ struct i2c_msg msgs[2];
+ u8 addr = SFP_PAGE;
+
+ msgs[0].addr = bus_addr;
+ msgs[0].flags = 0;
+ msgs[0].len = 1;
+ msgs[0].buf = &addr;
+
+ msgs[1].addr = bus_addr;
+ msgs[1].flags = I2C_M_RD;
+ msgs[1].len = 1;
+ msgs[1].buf = page;
+
+ return __i2c_transfer_err(i2c, msgs, 2);
+}
+
+static int __i2c_rollball_set_page(struct i2c_adapter *i2c, int bus_addr,
+ u8 page)
+{
+ struct i2c_msg msg;
+ u8 buf[2];
+
+ buf[0] = SFP_PAGE;
+ buf[1] = page;
+
+ msg.addr = bus_addr;
+ msg.flags = 0;
+ msg.len = 2;
+ msg.buf = buf;
+
+ return __i2c_transfer_err(i2c, &msg, 1);
+}
+
+/* In order to not interfere with other SFP code (which possibly may manipulate
+ * SFP_PAGE), for every transfer we do this:
+ * 1. lock the bus
+ * 2. save content of SFP_PAGE
+ * 3. set SFP_PAGE to 3
+ * 4. do the transfer
+ * 5. restore original SFP_PAGE
+ * 6. unlock the bus
+ * Note that one might think that steps 2 to 5 could be theoretically done all
+ * in one call to i2c_transfer (by constructing msgs array in such a way), but
+ * unfortunately tests show that this does not work :-( Changed SFP_PAGE does
+ * not take into account until i2c_transfer() is done.
+ */
+static int i2c_transfer_rollball(struct i2c_adapter *i2c,
+ struct i2c_msg *msgs, int num)
+{
+ int ret, main_err = 0;
+ u8 saved_page;
+
+ i2c_lock_bus(i2c, I2C_LOCK_SEGMENT);
+
+ /* save original page */
+ ret = __i2c_rollball_get_page(i2c, msgs->addr, &saved_page);
+ if (ret)
+ goto unlock;
+
+ /* change to RollBall MDIO page */
+ ret = __i2c_rollball_set_page(i2c, msgs->addr, SFP_PAGE_ROLLBALL_MDIO);
+ if (ret)
+ goto unlock;
+
+ /* do the transfer; we try to restore original page if this fails */
+ ret = __i2c_transfer_err(i2c, msgs, num);
+ if (ret)
+ main_err = ret;
+
+ /* restore original page */
+ ret = __i2c_rollball_set_page(i2c, msgs->addr, saved_page);
+
+unlock:
+ i2c_unlock_bus(i2c, I2C_LOCK_SEGMENT);
+
+ return main_err ? : ret;
+}
+
+static int i2c_rollball_mii_poll(struct mii_bus *bus, int bus_addr, u8 *buf,
+ size_t len)
+{
+ struct i2c_adapter *i2c = bus->priv;
+ struct i2c_msg msgs[2];
+ u8 cmd_addr, tmp, *res;
+ int i, ret;
+
+ cmd_addr = ROLLBALL_CMD_ADDR;
+
+ res = buf ? buf : &tmp;
+ len = buf ? len : 1;
+
+ msgs[0].addr = bus_addr;
+ msgs[0].flags = 0;
+ msgs[0].len = 1;
+ msgs[0].buf = &cmd_addr;
+
+ msgs[1].addr = bus_addr;
+ msgs[1].flags = I2C_M_RD;
+ msgs[1].len = len;
+ msgs[1].buf = res;
+
+ /* By experiment it takes up to 70 ms to access a register for these
+ * SFPs. Sleep 20ms between iterations and try 10 times.
+ */
+ i = 10;
+ do {
+ msleep(20);
+
+ ret = i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
+ if (ret)
+ return ret;
+
+ if (*res == ROLLBALL_CMD_DONE)
+ return 0;
+ } while (i-- > 0);
+
+ dev_dbg(&bus->dev, "poll timed out\n");
+
+ return -ETIMEDOUT;
+}
+
+static int i2c_rollball_mii_cmd(struct mii_bus *bus, int bus_addr, u8 cmd,
+ u8 *data, size_t len)
+{
+ struct i2c_adapter *i2c = bus->priv;
+ struct i2c_msg msgs[2];
+ u8 cmdbuf[2];
+
+ cmdbuf[0] = ROLLBALL_CMD_ADDR;
+ cmdbuf[1] = cmd;
+
+ msgs[0].addr = bus_addr;
+ msgs[0].flags = 0;
+ msgs[0].len = len;
+ msgs[0].buf = data;
+
+ msgs[1].addr = bus_addr;
+ msgs[1].flags = 0;
+ msgs[1].len = sizeof(cmdbuf);
+ msgs[1].buf = cmdbuf;
+
+ return i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
+}
+
+static int i2c_mii_read_rollball(struct mii_bus *bus, int phy_id, int reg)
+{
+ u8 buf[4], res[6];
+ int bus_addr, ret;
+ u16 val;
+
+ if (!(reg & MII_ADDR_C45))
+ return -EOPNOTSUPP;
+
+ bus_addr = i2c_mii_phy_addr(phy_id);
+ if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
+ return 0xffff;
+
+ buf[0] = ROLLBALL_DATA_ADDR;
+ buf[1] = (reg >> 16) & 0x1f;
+ buf[2] = (reg >> 8) & 0xff;
+ buf[3] = reg & 0xff;
+
+ ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_READ, buf,
+ sizeof(buf));
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_rollball_mii_poll(bus, bus_addr, res, sizeof(res));
+ if (ret == -ETIMEDOUT)
+ return 0xffff;
+ else if (ret < 0)
+ return ret;
+
+ val = res[4] << 8 | res[5];
+
+ return val;
+}
+
+static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int reg,
+ u16 val)
+{
+ int bus_addr, ret;
+ u8 buf[6];
+
+ if (!(reg & MII_ADDR_C45))
+ return -EOPNOTSUPP;
+
+ bus_addr = i2c_mii_phy_addr(phy_id);
+ if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
+ return 0;
+
+ buf[0] = ROLLBALL_DATA_ADDR;
+ buf[1] = (reg >> 16) & 0x1f;
+ buf[2] = (reg >> 8) & 0xff;
+ buf[3] = reg & 0xff;
+ buf[4] = val >> 8;
+ buf[5] = val & 0xff;
+
+ ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_WRITE, buf,
+ sizeof(buf));
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_rollball_mii_poll(bus, bus_addr, NULL, 0);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+
+static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
+{
+ struct i2c_msg msg;
+ u8 pw[5];
+ int ret;
+
+ pw[0] = ROLLBALL_PASSWORD;
+ pw[1] = 0xff;
+ pw[2] = 0xff;
+ pw[3] = 0xff;
+ pw[4] = 0xff;
+
+ msg.addr = ROLLBALL_PHY_I2C_ADDR;
+ msg.flags = 0;
+ msg.len = sizeof(pw);
+ msg.buf = pw;
+
+ ret = i2c_transfer(i2c, &msg, 1);
+ if (ret < 0)
+ return ret;
+ else if (ret != 1)
+ return -EIO;
+ else
+ return 0;
+}
+
+struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
+ enum mdio_i2c_proto protocol)
{
struct mii_bus *mii;
+ int ret;
if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
return ERR_PTR(-EINVAL);
snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
mii->parent = parent;
- mii->read = i2c_mii_read;
- mii->write = i2c_mii_write;
mii->priv = i2c;
+ switch (protocol) {
+ case MDIO_I2C_ROLLBALL:
+ ret = i2c_mii_init_rollball(i2c);
+ if (ret < 0) {
+ dev_err(parent,
+ "Cannot initialize RollBall MDIO I2C protocol: %d\n",
+ ret);
+ mdiobus_free(mii);
+ return ERR_PTR(ret);
+ }
+
+ mii->read = i2c_mii_read_rollball;
+ mii->write = i2c_mii_write_rollball;
+ break;
+ default:
+ mii->read = i2c_mii_read_default;
+ mii->write = i2c_mii_write_default;
+ break;
+ }
+
return mii;
}
EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
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