// SPDX-License-Identifier: GPL-2.0
/*
* 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
* our PHY drivers access to these PHYs, and so allowing configuration
* of their settings.
*/
#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
* specified to be present in SFP modules. These correspond with PHY
* addresses 16 and 17. Disallow access to these "phy" addresses.
*/
static bool i2c_mii_valid_phy_id(int phy_id)
{
return phy_id != 0x10 && phy_id != 0x11;
}
static unsigned int i2c_mii_phy_addr(int phy_id)
{
return phy_id + 0x40;
}
static int i2c_mii_read_default_c45(struct mii_bus *bus, int phy_id, int devad,
int reg)
{
struct i2c_adapter *i2c = bus->priv;
struct i2c_msg msgs[2];
u8 addr[3], data[2], *p;
int bus_addr, ret;
if (!i2c_mii_valid_phy_id(phy_id))
return 0xffff;
p = addr;
if (devad >= 0) {
*p++ = 0x20 | devad;
*p++ = reg >> 8;
}
*p++ = reg;
bus_addr = i2c_mii_phy_addr(phy_id);
msgs[0].addr = bus_addr;
msgs[0].flags = 0;
msgs[0].len = p - addr;
msgs[0].buf = addr;
msgs[1].addr = bus_addr;
msgs[1].flags = I2C_M_RD;
msgs[1].len = sizeof(data);
msgs[1].buf = data;
ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
if (ret != ARRAY_SIZE(msgs))
return 0xffff;
return data[0] << 8 | data[1];
}
static int i2c_mii_write_default_c45(struct mii_bus *bus, int phy_id,
int devad, int reg, u16 val)
{
struct i2c_adapter *i2c = bus->priv;
struct i2c_msg msg;
int ret;
u8 data[5], *p;
if (!i2c_mii_valid_phy_id(phy_id))
return 0;
p = data;
if (devad >= 0) {
*p++ = devad;
*p++ = reg >> 8;
}
*p++ = reg;
*p++ = val >> 8;
*p++ = val;
msg.addr = i2c_mii_phy_addr(phy_id);
msg.flags = 0;
msg.len = p - data;
msg.buf = data;
ret = i2c_transfer(i2c, &msg, 1);
return ret < 0 ? ret : 0;
}
static int i2c_mii_read_default_c22(struct mii_bus *bus, int phy_id, int reg)
{
return i2c_mii_read_default_c45(bus, phy_id, -1, reg);
}
static int i2c_mii_write_default_c22(struct mii_bus *bus, int phy_id, int reg,
u16 val)
{
return i2c_mii_write_default_c45(bus, phy_id, -1, reg, val);
}
/* 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 devad,
int reg)
{
u8 buf[4], res[6];
int bus_addr, ret;
u16 val;
bus_addr = i2c_mii_phy_addr(phy_id);
if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
return 0xffff;
buf[0] = ROLLBALL_DATA_ADDR;
buf[1] = devad;
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 devad,
int reg, u16 val)
{
int bus_addr, ret;
u8 buf[6];
bus_addr = i2c_mii_phy_addr(phy_id);
if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
return 0;
buf[0] = ROLLBALL_DATA_ADDR;
buf[1] = devad;
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);
mii = mdiobus_alloc();
if (!mii)
return ERR_PTR(-ENOMEM);
snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
mii->parent = parent;
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_c45 = i2c_mii_read_rollball;
mii->write_c45 = i2c_mii_write_rollball;
break;
default:
mii->read = i2c_mii_read_default_c22;
mii->write = i2c_mii_write_default_c22;
mii->read_c45 = i2c_mii_read_default_c45;
mii->write_c45 = i2c_mii_write_default_c45;
break;
}
return mii;
}
EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
MODULE_AUTHOR("Russell King");
MODULE_DESCRIPTION("MDIO I2C bridge library");
MODULE_LICENSE("GPL v2");
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