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authorRussell King <rmk+kernel@arm.linux.org.uk>2015-09-25 17:43:52 +0100
committerRussell King <rmk+kernel@armlinux.org.uk>2017-07-07 16:12:14 +0100
commitcdd55dc507b8edea0d72a320858096645072c254 (patch)
tree157dc5153032fdf953fbc1cc0de341bf76d29ee5
parentf6e45201064ce220d35b1a70c4048f88785a4ed5 (diff)
net: phy: add I2C mdio bus
Add an I2C MDIO bus bridge library, to allow phylib to access PHYs which are connected to an I2C bus instead of the more conventional MDIO bus. Such PHYs can be found in SFP adapters and SFF modules. Since PHYs appear at I2C bus address 0x40..0x5f, and 0x50/0x51 are reserved for SFP EEPROMs/diagnostics, we must not allow the MDIO bus to access these I2C addresses. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--drivers/net/phy/Kconfig10
-rw-r--r--drivers/net/phy/Makefile1
-rw-r--r--drivers/net/phy/mdio-i2c.c109
-rw-r--r--drivers/net/phy/mdio-i2c.h19
4 files changed, 139 insertions, 0 deletions
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 1c48353cb300..0bfd17a54fab 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -98,6 +98,16 @@ config MDIO_HISI_FEMAC
This module provides a driver for the MDIO busses found in the
Hisilicon SoC that have an Fast Ethernet MAC.
+config MDIO_I2C
+ tristate
+ depends on I2C
+ help
+ Support I2C based PHYs. This provides a MDIO bus bridged
+ to I2C to allow PHYs connected in I2C mode to be accessed
+ using the existing infrastructure.
+
+ This is library mode.
+
config MDIO_MOXART
tristate "MOXA ART MDIO interface support"
depends on ARCH_MOXART
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index dd6fed52d5bc..4ee0e2907cc0 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_MDIO_BUS_MUX_MMIOREG) += mdio-mux-mmioreg.o
obj-$(CONFIG_MDIO_CAVIUM) += mdio-cavium.o
obj-$(CONFIG_MDIO_GPIO) += mdio-gpio.o
obj-$(CONFIG_MDIO_HISI_FEMAC) += mdio-hisi-femac.o
+obj-$(CONFIG_MDIO_I2C) += mdio-i2c.o
obj-$(CONFIG_MDIO_MOXART) += mdio-moxart.o
obj-$(CONFIG_MDIO_OCTEON) += mdio-octeon.o
obj-$(CONFIG_MDIO_SUN4I) += mdio-sun4i.o
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");
diff --git a/drivers/net/phy/mdio-i2c.h b/drivers/net/phy/mdio-i2c.h
new file mode 100644
index 000000000000..889ab57d7f3e
--- /dev/null
+++ b/drivers/net/phy/mdio-i2c.h
@@ -0,0 +1,19 @@
+/*
+ * MDIO I2C bridge
+ *
+ * Copyright (C) 2015 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.
+ */
+#ifndef MDIO_I2C_H
+#define MDIO_I2C_H
+
+struct device;
+struct i2c_adapter;
+struct mii_bus;
+
+struct mii_bus *mdio_i2c_alloc(struct device *parent, struct i2c_adapter *i2c);
+
+#endif