426 lines
9.1 KiB
C
426 lines
9.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* MDIO I2C bridge
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*
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* Copyright (C) 2015-2016 Russell King
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* Copyright (C) 2021 Marek Behun
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*
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* Network PHYs can appear on I2C buses when they are part of SFP module.
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* This driver exposes these PHYs to the networking PHY code, allowing
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* our PHY drivers access to these PHYs, and so allowing configuration
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* of their settings.
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*/
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#include <linux/i2c.h>
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#include <linux/mdio/mdio-i2c.h>
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#include <linux/phy.h>
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#include <linux/sfp.h>
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/*
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* I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is
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* specified to be present in SFP modules. These correspond with PHY
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* addresses 16 and 17. Disallow access to these "phy" addresses.
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*/
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static bool i2c_mii_valid_phy_id(int phy_id)
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{
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return phy_id != 0x10 && phy_id != 0x11;
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}
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static unsigned int i2c_mii_phy_addr(int phy_id)
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{
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return phy_id + 0x40;
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}
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static int i2c_mii_read_default_c45(struct mii_bus *bus, int phy_id, int devad,
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int reg)
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{
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struct i2c_adapter *i2c = bus->priv;
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struct i2c_msg msgs[2];
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u8 addr[3], data[2], *p;
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int bus_addr, ret;
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if (!i2c_mii_valid_phy_id(phy_id))
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return 0xffff;
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p = addr;
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if (devad >= 0) {
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*p++ = 0x20 | devad;
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*p++ = reg >> 8;
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}
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*p++ = reg;
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bus_addr = i2c_mii_phy_addr(phy_id);
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msgs[0].addr = bus_addr;
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msgs[0].flags = 0;
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msgs[0].len = p - addr;
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msgs[0].buf = addr;
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msgs[1].addr = bus_addr;
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msgs[1].flags = I2C_M_RD;
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msgs[1].len = sizeof(data);
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msgs[1].buf = data;
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ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
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if (ret != ARRAY_SIZE(msgs))
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return 0xffff;
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return data[0] << 8 | data[1];
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}
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static int i2c_mii_write_default_c45(struct mii_bus *bus, int phy_id,
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int devad, int reg, u16 val)
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{
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struct i2c_adapter *i2c = bus->priv;
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struct i2c_msg msg;
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int ret;
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u8 data[5], *p;
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if (!i2c_mii_valid_phy_id(phy_id))
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return 0;
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p = data;
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if (devad >= 0) {
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*p++ = devad;
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*p++ = reg >> 8;
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}
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*p++ = reg;
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*p++ = val >> 8;
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*p++ = val;
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msg.addr = i2c_mii_phy_addr(phy_id);
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msg.flags = 0;
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msg.len = p - data;
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msg.buf = data;
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ret = i2c_transfer(i2c, &msg, 1);
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return ret < 0 ? ret : 0;
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}
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static int i2c_mii_read_default_c22(struct mii_bus *bus, int phy_id, int reg)
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{
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return i2c_mii_read_default_c45(bus, phy_id, -1, reg);
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}
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static int i2c_mii_write_default_c22(struct mii_bus *bus, int phy_id, int reg,
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u16 val)
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{
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return i2c_mii_write_default_c45(bus, phy_id, -1, reg, val);
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}
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/* RollBall SFPs do not access internal PHY via I2C address 0x56, but
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* instead via address 0x51, when SFP page is set to 0x03 and password to
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* 0xffffffff.
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*
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* address size contents description
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* ------- ---- -------- -----------
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* 0x80 1 CMD 0x01/0x02/0x04 for write/read/done
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* 0x81 1 DEV Clause 45 device
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* 0x82 2 REG Clause 45 register
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* 0x84 2 VAL Register value
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*/
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#define ROLLBALL_PHY_I2C_ADDR 0x51
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#define ROLLBALL_PASSWORD (SFP_VSL + 3)
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#define ROLLBALL_CMD_ADDR 0x80
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#define ROLLBALL_DATA_ADDR 0x81
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#define ROLLBALL_CMD_WRITE 0x01
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#define ROLLBALL_CMD_READ 0x02
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#define ROLLBALL_CMD_DONE 0x04
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#define SFP_PAGE_ROLLBALL_MDIO 3
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static int __i2c_transfer_err(struct i2c_adapter *i2c, struct i2c_msg *msgs,
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int num)
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{
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int ret;
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ret = __i2c_transfer(i2c, msgs, num);
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if (ret < 0)
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return ret;
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else if (ret != num)
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return -EIO;
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else
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return 0;
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}
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static int __i2c_rollball_get_page(struct i2c_adapter *i2c, int bus_addr,
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u8 *page)
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{
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struct i2c_msg msgs[2];
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u8 addr = SFP_PAGE;
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msgs[0].addr = bus_addr;
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msgs[0].flags = 0;
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msgs[0].len = 1;
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msgs[0].buf = &addr;
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msgs[1].addr = bus_addr;
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msgs[1].flags = I2C_M_RD;
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msgs[1].len = 1;
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msgs[1].buf = page;
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return __i2c_transfer_err(i2c, msgs, 2);
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}
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static int __i2c_rollball_set_page(struct i2c_adapter *i2c, int bus_addr,
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u8 page)
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{
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struct i2c_msg msg;
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u8 buf[2];
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buf[0] = SFP_PAGE;
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buf[1] = page;
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msg.addr = bus_addr;
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msg.flags = 0;
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msg.len = 2;
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msg.buf = buf;
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return __i2c_transfer_err(i2c, &msg, 1);
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}
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/* In order to not interfere with other SFP code (which possibly may manipulate
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* SFP_PAGE), for every transfer we do this:
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* 1. lock the bus
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* 2. save content of SFP_PAGE
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* 3. set SFP_PAGE to 3
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* 4. do the transfer
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* 5. restore original SFP_PAGE
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* 6. unlock the bus
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* Note that one might think that steps 2 to 5 could be theoretically done all
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* in one call to i2c_transfer (by constructing msgs array in such a way), but
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* unfortunately tests show that this does not work :-( Changed SFP_PAGE does
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* not take into account until i2c_transfer() is done.
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*/
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static int i2c_transfer_rollball(struct i2c_adapter *i2c,
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struct i2c_msg *msgs, int num)
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{
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int ret, main_err = 0;
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u8 saved_page;
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i2c_lock_bus(i2c, I2C_LOCK_SEGMENT);
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/* save original page */
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ret = __i2c_rollball_get_page(i2c, msgs->addr, &saved_page);
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if (ret)
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goto unlock;
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/* change to RollBall MDIO page */
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ret = __i2c_rollball_set_page(i2c, msgs->addr, SFP_PAGE_ROLLBALL_MDIO);
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if (ret)
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goto unlock;
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/* do the transfer; we try to restore original page if this fails */
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ret = __i2c_transfer_err(i2c, msgs, num);
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if (ret)
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main_err = ret;
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/* restore original page */
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ret = __i2c_rollball_set_page(i2c, msgs->addr, saved_page);
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unlock:
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i2c_unlock_bus(i2c, I2C_LOCK_SEGMENT);
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return main_err ? : ret;
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}
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static int i2c_rollball_mii_poll(struct mii_bus *bus, int bus_addr, u8 *buf,
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size_t len)
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{
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struct i2c_adapter *i2c = bus->priv;
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struct i2c_msg msgs[2];
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u8 cmd_addr, tmp, *res;
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int i, ret;
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cmd_addr = ROLLBALL_CMD_ADDR;
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res = buf ? buf : &tmp;
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len = buf ? len : 1;
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msgs[0].addr = bus_addr;
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msgs[0].flags = 0;
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msgs[0].len = 1;
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msgs[0].buf = &cmd_addr;
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msgs[1].addr = bus_addr;
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msgs[1].flags = I2C_M_RD;
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msgs[1].len = len;
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msgs[1].buf = res;
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/* By experiment it takes up to 70 ms to access a register for these
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* SFPs. Sleep 20ms between iterations and try 10 times.
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*/
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i = 10;
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do {
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msleep(20);
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ret = i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
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if (ret)
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return ret;
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if (*res == ROLLBALL_CMD_DONE)
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return 0;
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} while (i-- > 0);
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dev_dbg(&bus->dev, "poll timed out\n");
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return -ETIMEDOUT;
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}
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static int i2c_rollball_mii_cmd(struct mii_bus *bus, int bus_addr, u8 cmd,
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u8 *data, size_t len)
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{
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struct i2c_adapter *i2c = bus->priv;
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struct i2c_msg msgs[2];
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u8 cmdbuf[2];
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cmdbuf[0] = ROLLBALL_CMD_ADDR;
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cmdbuf[1] = cmd;
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msgs[0].addr = bus_addr;
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msgs[0].flags = 0;
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msgs[0].len = len;
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msgs[0].buf = data;
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msgs[1].addr = bus_addr;
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msgs[1].flags = 0;
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msgs[1].len = sizeof(cmdbuf);
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msgs[1].buf = cmdbuf;
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return i2c_transfer_rollball(i2c, msgs, ARRAY_SIZE(msgs));
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}
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static int i2c_mii_read_rollball(struct mii_bus *bus, int phy_id, int reg)
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{
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u8 buf[4], res[6];
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int bus_addr, ret;
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u16 val;
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bus_addr = i2c_mii_phy_addr(phy_id);
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if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
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return 0xffff;
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buf[0] = ROLLBALL_DATA_ADDR;
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buf[1] = (reg >> 16) & 0x1f;
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buf[2] = (reg >> 8) & 0xff;
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buf[3] = reg & 0xff;
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ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_READ, buf,
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sizeof(buf));
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if (ret < 0)
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return ret;
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ret = i2c_rollball_mii_poll(bus, bus_addr, res, sizeof(res));
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if (ret == -ETIMEDOUT)
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return 0xffff;
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else if (ret < 0)
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return ret;
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val = res[4] << 8 | res[5];
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return val;
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}
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static int i2c_mii_write_rollball(struct mii_bus *bus, int phy_id, int reg,
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u16 val)
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{
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int bus_addr, ret;
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u8 buf[6];
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bus_addr = i2c_mii_phy_addr(phy_id);
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if (bus_addr != ROLLBALL_PHY_I2C_ADDR)
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return 0;
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buf[0] = ROLLBALL_DATA_ADDR;
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buf[1] = (reg >> 16) & 0x1f;
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buf[2] = (reg >> 8) & 0xff;
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buf[3] = reg & 0xff;
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buf[4] = val >> 8;
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buf[5] = val & 0xff;
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ret = i2c_rollball_mii_cmd(bus, bus_addr, ROLLBALL_CMD_WRITE, buf,
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sizeof(buf));
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if (ret < 0)
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return ret;
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ret = i2c_rollball_mii_poll(bus, bus_addr, NULL, 0);
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if (ret < 0)
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return ret;
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return 0;
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}
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static int i2c_mii_init_rollball(struct i2c_adapter *i2c)
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{
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struct i2c_msg msg;
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u8 pw[5];
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int ret;
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pw[0] = ROLLBALL_PASSWORD;
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pw[1] = 0xff;
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pw[2] = 0xff;
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pw[3] = 0xff;
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pw[4] = 0xff;
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msg.addr = ROLLBALL_PHY_I2C_ADDR;
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msg.flags = 0;
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msg.len = sizeof(pw);
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msg.buf = pw;
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ret = i2c_transfer(i2c, &msg, 1);
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if (ret < 0)
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return ret;
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else if (ret != 1)
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return -EIO;
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else
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return 0;
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}
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struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c,
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enum mdio_i2c_proto protocol)
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{
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struct mii_bus *mii;
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int ret;
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if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
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return ERR_PTR(-EINVAL);
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mii = mdiobus_alloc();
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if (!mii)
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return ERR_PTR(-ENOMEM);
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snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
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mii->parent = parent;
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mii->priv = i2c;
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switch (protocol) {
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case MDIO_I2C_ROLLBALL:
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ret = i2c_mii_init_rollball(i2c);
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if (ret < 0) {
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dev_err(parent,
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"Cannot initialize RollBall MDIO I2C protocol: %d\n",
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ret);
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mdiobus_free(mii);
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return ERR_PTR(ret);
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}
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mii->read = i2c_mii_read_rollball;
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mii->write = i2c_mii_write_rollball;
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break;
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default:
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mii->read = i2c_mii_read_default_c22;
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mii->write = i2c_mii_write_default_c22;
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mii->read_c45 = i2c_mii_read_default_c45;
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mii->write_c45 = i2c_mii_write_default_c45;
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break;
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}
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return mii;
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}
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EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
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MODULE_AUTHOR("Russell King");
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MODULE_DESCRIPTION("MDIO I2C bridge library");
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MODULE_LICENSE("GPL v2");
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