tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * MDIO I2C bridge
3 *
4 * Copyright (C) 2015-2016 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Network PHYs can appear on I2C buses when they are part of SFP module.
11 * This driver exposes these PHYs to the networking PHY code, allowing
12 * our PHY drivers access to these PHYs, and so allowing configuration
13 * of their settings.
14 */
15#include <linux/i2c.h>
16#include <linux/phy.h>
17
18#include "mdio-i2c.h"
19
20/*
21 * I2C bus addresses 0x50 and 0x51 are normally an EEPROM, which is
22 * specified to be present in SFP modules. These correspond with PHY
23 * addresses 16 and 17. Disallow access to these "phy" addresses.
24 */
25static bool i2c_mii_valid_phy_id(int phy_id)
26{
27 return phy_id != 0x10 && phy_id != 0x11;
28}
29
30static unsigned int i2c_mii_phy_addr(int phy_id)
31{
32 return phy_id + 0x40;
33}
34
35static int i2c_mii_read(struct mii_bus *bus, int phy_id, int reg)
36{
37 struct i2c_adapter *i2c = bus->priv;
38 struct i2c_msg msgs[2];
39 u8 data[2], dev_addr = reg;
40 int bus_addr, ret;
41
42 if (!i2c_mii_valid_phy_id(phy_id))
43 return 0xffff;
44
45 bus_addr = i2c_mii_phy_addr(phy_id);
46 msgs[0].addr = bus_addr;
47 msgs[0].flags = 0;
48 msgs[0].len = 1;
49 msgs[0].buf = &dev_addr;
50 msgs[1].addr = bus_addr;
51 msgs[1].flags = I2C_M_RD;
52 msgs[1].len = sizeof(data);
53 msgs[1].buf = data;
54
55 ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
56 if (ret != ARRAY_SIZE(msgs))
57 return 0xffff;
58
59 return data[0] << 8 | data[1];
60}
61
62static int i2c_mii_write(struct mii_bus *bus, int phy_id, int reg, u16 val)
63{
64 struct i2c_adapter *i2c = bus->priv;
65 struct i2c_msg msg;
66 int ret;
67 u8 data[3];
68
69 if (!i2c_mii_valid_phy_id(phy_id))
70 return 0;
71
72 data[0] = reg;
73 data[1] = val >> 8;
74 data[2] = val;
75
76 msg.addr = i2c_mii_phy_addr(phy_id);
77 msg.flags = 0;
78 msg.len = 3;
79 msg.buf = data;
80
81 ret = i2c_transfer(i2c, &msg, 1);
82
83 return ret < 0 ? ret : 0;
84}
85
86struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c)
87{
88 struct mii_bus *mii;
89
90 if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
91 return ERR_PTR(-EINVAL);
92
93 mii = mdiobus_alloc();
94 if (!mii)
95 return ERR_PTR(-ENOMEM);
96
97 snprintf(mii->id, MII_BUS_ID_SIZE, "i2c:%s", dev_name(parent));
98 mii->parent = parent;
99 mii->read = i2c_mii_read;
100 mii->write = i2c_mii_write;
101 mii->priv = i2c;
102
103 return mii;
104}
105EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
106
107MODULE_AUTHOR("Russell King");
108MODULE_DESCRIPTION("MDIO I2C bridge library");
109MODULE_LICENSE("GPL v2");