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path: root/drivers/net/phy/mdio-i2c.c
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Diffstat (limited to 'drivers/net/phy/mdio-i2c.c')
-rw-r--r--drivers/net/phy/mdio-i2c.c109
1 files changed, 109 insertions, 0 deletions
diff --git a/drivers/net/phy/mdio-i2c.c b/drivers/net/phy/mdio-i2c.c
new file mode 100644
index 000000000000..6d24fd13ca86
--- /dev/null
+++ b/drivers/net/phy/mdio-i2c.c
@@ -0,0 +1,109 @@
+/*
+ * MDIO I2C bridge
+ *
+ * Copyright (C) 2015-2016 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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/phy.h>
+
+#include "mdio-i2c.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(struct mii_bus *bus, int phy_id, int reg)
+{
+ struct i2c_adapter *i2c = bus->priv;
+ struct i2c_msg msgs[2];
+ u8 data[2], dev_addr = reg;
+ int bus_addr, ret;
+
+ if (!i2c_mii_valid_phy_id(phy_id))
+ return 0xffff;
+
+ bus_addr = i2c_mii_phy_addr(phy_id);
+ msgs[0].addr = bus_addr;
+ msgs[0].flags = 0;
+ msgs[0].len = 1;
+ msgs[0].buf = &dev_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(struct mii_bus *bus, int phy_id, int reg, u16 val)
+{
+ struct i2c_adapter *i2c = bus->priv;
+ struct i2c_msg msg;
+ int ret;
+ u8 data[3];
+
+ if (!i2c_mii_valid_phy_id(phy_id))
+ return 0;
+
+ data[0] = reg;
+ data[1] = val >> 8;
+ data[2] = val;
+
+ msg.addr = i2c_mii_phy_addr(phy_id);
+ msg.flags = 0;
+ msg.len = 3;
+ msg.buf = data;
+
+ ret = i2c_transfer(i2c, &msg, 1);
+
+ return ret < 0 ? ret : 0;
+}
+
+struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c)
+{
+ struct mii_bus *mii;
+
+ 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->read = i2c_mii_read;
+ mii->write = i2c_mii_write;
+ mii->priv = i2c;
+
+ return mii;
+}
+EXPORT_SYMBOL_GPL(mdio_i2c_alloc);
+
+MODULE_AUTHOR("Russell King");
+MODULE_DESCRIPTION("MDIO I2C bridge library");
+MODULE_LICENSE("GPL v2");