sfp: add SFP module support

Add support for SFP hotpluggable modules via sfp-bus and phylink.
This supports both copper and optical SFP modules, which require
different Serdes modes in order to properly negotiate the link.

Optical SFP modules typically require the Serdes link to be talking
1000BaseX mode - this is the gigabit ethernet mode defined by the
802.3 standard.

Copper SFP modules typically integrate a PHY in the module to convert
from Serdes to copper, and the PHY will be configured by the vendor
to either present a 1000BaseX Serdes link (for fixed 1000BaseT) or a
SGMII Serdes link.  However, this is vendor defined, so we instead
detect the PHY, switch the link to SGMII mode, and use traditional
PHY based negotiation.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 921 insertions, 0 deletions

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index a0a9e03..bf73969 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -200,6 +200,11 @@ config LED_TRIGGER_PHY
 
 comment "MII PHY device drivers"
 
+config SFP
+	tristate "SFP cage support"
+	depends on I2C && PHYLINK
+	select MDIO_I2C
+
 config AMD_PHY
 	tristate "AMD PHYs"
 	---help---
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 4c16a10..7237255 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_MDIO_SUN4I)	+= mdio-sun4i.o
 obj-$(CONFIG_MDIO_THUNDER)	+= mdio-thunder.o
 obj-$(CONFIG_MDIO_XGENE)	+= mdio-xgene.o
 
+obj-$(CONFIG_SFP)		+= sfp.o
 sfp-obj-$(CONFIG_SFP)		+= sfp-bus.o
 obj-y				+= $(sfp-obj-y) $(sfp-obj-m)
 
diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
new file mode 100644
index 0000000..fb2cf43
--- /dev/null
+++ b/drivers/net/phy/sfp.c
@@ -0,0 +1,915 @@
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#include "mdio-i2c.h"
+#include "sfp.h"
+#include "swphy.h"
+
+enum {
+	GPIO_MODDEF0,
+	GPIO_LOS,
+	GPIO_TX_FAULT,
+	GPIO_TX_DISABLE,
+	GPIO_RATE_SELECT,
+	GPIO_MAX,
+
+	SFP_F_PRESENT = BIT(GPIO_MODDEF0),
+	SFP_F_LOS = BIT(GPIO_LOS),
+	SFP_F_TX_FAULT = BIT(GPIO_TX_FAULT),
+	SFP_F_TX_DISABLE = BIT(GPIO_TX_DISABLE),
+	SFP_F_RATE_SELECT = BIT(GPIO_RATE_SELECT),
+
+	SFP_E_INSERT = 0,
+	SFP_E_REMOVE,
+	SFP_E_DEV_DOWN,
+	SFP_E_DEV_UP,
+	SFP_E_TX_FAULT,
+	SFP_E_TX_CLEAR,
+	SFP_E_LOS_HIGH,
+	SFP_E_LOS_LOW,
+	SFP_E_TIMEOUT,
+
+	SFP_MOD_EMPTY = 0,
+	SFP_MOD_PROBE,
+	SFP_MOD_PRESENT,
+	SFP_MOD_ERROR,
+
+	SFP_DEV_DOWN = 0,
+	SFP_DEV_UP,
+
+	SFP_S_DOWN = 0,
+	SFP_S_INIT,
+	SFP_S_WAIT_LOS,
+	SFP_S_LINK_UP,
+	SFP_S_TX_FAULT,
+	SFP_S_REINIT,
+	SFP_S_TX_DISABLE,
+};
+
+static const char *gpio_of_names[] = {
+	"moddef0",
+	"los",
+	"tx-fault",
+	"tx-disable",
+	"rate-select",
+};
+
+static const enum gpiod_flags gpio_flags[] = {
+	GPIOD_IN,
+	GPIOD_IN,
+	GPIOD_IN,
+	GPIOD_ASIS,
+	GPIOD_ASIS,
+};
+
+#define T_INIT_JIFFIES	msecs_to_jiffies(300)
+#define T_RESET_US	10
+#define T_FAULT_RECOVER	msecs_to_jiffies(1000)
+
+/* SFP module presence detection is poor: the three MOD DEF signals are
+ * the same length on the PCB, which means it's possible for MOD DEF 0 to
+ * connect before the I2C bus on MOD DEF 1/2.
+ *
+ * The SFP MSA specifies 300ms as t_init (the time taken for TX_FAULT to
+ * be deasserted) but makes no mention of the earliest time before we can
+ * access the I2C EEPROM.  However, Avago modules require 300ms.
+ */
+#define T_PROBE_INIT	msecs_to_jiffies(300)
+#define T_PROBE_RETRY	msecs_to_jiffies(100)
+
+/*
+ * SFP modules appear to always have their PHY configured for bus address
+ * 0x56 (which with mdio-i2c, translates to a PHY address of 22).
+ */
+#define SFP_PHY_ADDR	22
+
+/*
+ * Give this long for the PHY to reset.
+ */
+#define T_PHY_RESET_MS	50
+
+static DEFINE_MUTEX(sfp_mutex);
+
+struct sfp {
+	struct device *dev;
+	struct i2c_adapter *i2c;
+	struct mii_bus *i2c_mii;
+	struct sfp_bus *sfp_bus;
+	struct phy_device *mod_phy;
+
+	unsigned int (*get_state)(struct sfp *);
+	void (*set_state)(struct sfp *, unsigned int);
+	int (*read)(struct sfp *, bool, u8, void *, size_t);
+
+	struct gpio_desc *gpio[GPIO_MAX];
+
+	unsigned int state;
+	struct delayed_work poll;
+	struct delayed_work timeout;
+	struct mutex sm_mutex;
+	unsigned char sm_mod_state;
+	unsigned char sm_dev_state;
+	unsigned short sm_state;
+	unsigned int sm_retries;
+
+	struct sfp_eeprom_id id;
+};
+
+static unsigned long poll_jiffies;
+
+static unsigned int sfp_gpio_get_state(struct sfp *sfp)
+{
+	unsigned int i, state, v;
+
+	for (i = state = 0; i < GPIO_MAX; i++) {
+		if (gpio_flags[i] != GPIOD_IN || !sfp->gpio[i])
+			continue;
+
+		v = gpiod_get_value_cansleep(sfp->gpio[i]);
+		if (v)
+			state |= BIT(i);
+	}
+
+	return state;
+}
+
+static void sfp_gpio_set_state(struct sfp *sfp, unsigned int state)
+{
+	if (state & SFP_F_PRESENT) {
+		/* If the module is present, drive the signals */
+		if (sfp->gpio[GPIO_TX_DISABLE])
+			gpiod_direction_output(sfp->gpio[GPIO_TX_DISABLE],
+						state & SFP_F_TX_DISABLE);
+		if (state & SFP_F_RATE_SELECT)
+			gpiod_direction_output(sfp->gpio[GPIO_RATE_SELECT],
+						state & SFP_F_RATE_SELECT);
+	} else {
+		/* Otherwise, let them float to the pull-ups */
+		if (sfp->gpio[GPIO_TX_DISABLE])
+			gpiod_direction_input(sfp->gpio[GPIO_TX_DISABLE]);
+		if (state & SFP_F_RATE_SELECT)
+			gpiod_direction_input(sfp->gpio[GPIO_RATE_SELECT]);
+	}
+}
+
+static int sfp__i2c_read(struct i2c_adapter *i2c, u8 bus_addr, u8 dev_addr,
+	void *buf, size_t len)
+{
+	struct i2c_msg msgs[2];
+	int ret;
+
+	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 = len;
+	msgs[1].buf = buf;
+
+	ret = i2c_transfer(i2c, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		return ret;
+
+	return ret == ARRAY_SIZE(msgs) ? len : 0;
+}
+
+static int sfp_i2c_read(struct sfp *sfp, bool a2, u8 addr, void *buf,
+	size_t len)
+{
+	return sfp__i2c_read(sfp->i2c, a2 ? 0x51 : 0x50, addr, buf, len);
+}
+
+static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c)
+{
+	struct mii_bus *i2c_mii;
+	int ret;
+
+	if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
+		return -EINVAL;
+
+	sfp->i2c = i2c;
+	sfp->read = sfp_i2c_read;
+
+	i2c_mii = mdio_i2c_alloc(sfp->dev, i2c);
+	if (IS_ERR(i2c_mii))
+		return PTR_ERR(i2c_mii);
+
+	i2c_mii->name = "SFP I2C Bus";
+	i2c_mii->phy_mask = ~0;
+
+	ret = mdiobus_register(i2c_mii);
+	if (ret < 0) {
+		mdiobus_free(i2c_mii);
+		return ret;
+	}
+
+	sfp->i2c_mii = i2c_mii;
+
+	return 0;
+}
+
+
+/* Interface */
+static unsigned int sfp_get_state(struct sfp *sfp)
+{
+	return sfp->get_state(sfp);
+}
+
+static void sfp_set_state(struct sfp *sfp, unsigned int state)
+{
+	sfp->set_state(sfp, state);
+}
+
+static int sfp_read(struct sfp *sfp, bool a2, u8 addr, void *buf, size_t len)
+{
+	return sfp->read(sfp, a2, addr, buf, len);
+}
+
+static unsigned int sfp_check(void *buf, size_t len)
+{
+	u8 *p, check;
+
+	for (p = buf, check = 0; len; p++, len--)
+		check += *p;
+
+	return check;
+}
+
+/* Helpers */
+static void sfp_module_tx_disable(struct sfp *sfp)
+{
+	dev_dbg(sfp->dev, "tx disable %u -> %u\n",
+		sfp->state & SFP_F_TX_DISABLE ? 1 : 0, 1);
+	sfp->state |= SFP_F_TX_DISABLE;
+	sfp_set_state(sfp, sfp->state);
+}
+
+static void sfp_module_tx_enable(struct sfp *sfp)
+{
+	dev_dbg(sfp->dev, "tx disable %u -> %u\n",
+		sfp->state & SFP_F_TX_DISABLE ? 1 : 0, 0);
+	sfp->state &= ~SFP_F_TX_DISABLE;
+	sfp_set_state(sfp, sfp->state);
+}
+
+static void sfp_module_tx_fault_reset(struct sfp *sfp)
+{
+	unsigned int state = sfp->state;
+
+	if (state & SFP_F_TX_DISABLE)
+		return;
+
+	sfp_set_state(sfp, state | SFP_F_TX_DISABLE);
+
+	udelay(T_RESET_US);
+
+	sfp_set_state(sfp, state);
+}
+
+/* SFP state machine */
+static void sfp_sm_set_timer(struct sfp *sfp, unsigned int timeout)
+{
+	if (timeout)
+		mod_delayed_work(system_power_efficient_wq, &sfp->timeout,
+				 timeout);
+	else
+		cancel_delayed_work(&sfp->timeout);
+}
+
+static void sfp_sm_next(struct sfp *sfp, unsigned int state,
+			unsigned int timeout)
+{
+	sfp->sm_state = state;
+	sfp_sm_set_timer(sfp, timeout);
+}
+
+static void sfp_sm_ins_next(struct sfp *sfp, unsigned int state, unsigned int timeout)
+{
+	sfp->sm_mod_state = state;
+	sfp_sm_set_timer(sfp, timeout);
+}
+
+static void sfp_sm_phy_detach(struct sfp *sfp)
+{
+	phy_stop(sfp->mod_phy);
+	sfp_remove_phy(sfp->sfp_bus);
+	phy_device_remove(sfp->mod_phy);
+	phy_device_free(sfp->mod_phy);
+	sfp->mod_phy = NULL;
+}
+
+static void sfp_sm_probe_phy(struct sfp *sfp)
+{
+	struct phy_device *phy;
+	int err;
+
+	msleep(T_PHY_RESET_MS);
+
+	phy = mdiobus_scan(sfp->i2c_mii, SFP_PHY_ADDR);
+	if (IS_ERR(phy)) {
+		dev_err(sfp->dev, "mdiobus scan returned %ld\n", PTR_ERR(phy));
+		return;
+	}
+	if (!phy) {
+		dev_info(sfp->dev, "no PHY detected\n");
+		return;
+	}
+
+	err = sfp_add_phy(sfp->sfp_bus, phy);
+	if (err) {
+		phy_device_remove(phy);
+		phy_device_free(phy);
+		dev_err(sfp->dev, "sfp_add_phy failed: %d\n", err);
+		return;
+	}
+
+	sfp->mod_phy = phy;
+	phy_start(phy);
+}
+
+static void sfp_sm_link_up(struct sfp *sfp)
+{
+	sfp_link_up(sfp->sfp_bus);
+	sfp_sm_next(sfp, SFP_S_LINK_UP, 0);
+}
+
+static void sfp_sm_link_down(struct sfp *sfp)
+{
+	sfp_link_down(sfp->sfp_bus);
+}
+
+static void sfp_sm_link_check_los(struct sfp *sfp)
+{
+	unsigned int los = sfp->state & SFP_F_LOS;
+
+	/* FIXME: what if neither SFP_OPTIONS_LOS_INVERTED nor
+	 * SFP_OPTIONS_LOS_NORMAL are set?  For now, we assume
+	 * the same as SFP_OPTIONS_LOS_NORMAL set.
+	 */
+	if (sfp->id.ext.options & SFP_OPTIONS_LOS_INVERTED)
+		los ^= SFP_F_LOS;
+
+	if (los)
+		sfp_sm_next(sfp, SFP_S_WAIT_LOS, 0);
+	else
+		sfp_sm_link_up(sfp);
+}
+
+static void sfp_sm_fault(struct sfp *sfp, bool warn)
+{
+	if (sfp->sm_retries && !--sfp->sm_retries) {
+		dev_err(sfp->dev, "module persistently indicates fault, disabling\n");
+		sfp_sm_next(sfp, SFP_S_TX_DISABLE, 0);
+	} else {
+		if (warn)
+			dev_err(sfp->dev, "module transmit fault indicated\n");
+
+		sfp_sm_next(sfp, SFP_S_TX_FAULT, T_FAULT_RECOVER);
+	}
+}
+
+static void sfp_sm_mod_init(struct sfp *sfp)
+{
+	sfp_module_tx_enable(sfp);
+
+	/* Wait t_init before indicating that the link is up, provided the
+	 * current state indicates no TX_FAULT.  If TX_FAULT clears before
+	 * this time, that's fine too.
+	 */
+	sfp_sm_next(sfp, SFP_S_INIT, T_INIT_JIFFIES);
+	sfp->sm_retries = 5;
+
+	/* Setting the serdes link mode is guesswork: there's no
+	 * field in the EEPROM which indicates what mode should
+	 * be used.
+	 *
+	 * If it's a gigabit-only fiber module, it probably does
+	 * not have a PHY, so switch to 802.3z negotiation mode.
+	 * Otherwise, switch to SGMII mode (which is required to
+	 * support non-gigabit speeds) and probe for a PHY.
+	 */
+	if (sfp->id.base.e1000_base_t ||
+	    sfp->id.base.e100_base_lx ||
+	    sfp->id.base.e100_base_fx)
+		sfp_sm_probe_phy(sfp);
+}
+
+static int sfp_sm_mod_probe(struct sfp *sfp)
+{
+	/* SFP module inserted - read I2C data */
+	struct sfp_eeprom_id id;
+	char vendor[17];
+	char part[17];
+	char sn[17];
+	char date[9];
+	char rev[5];
+	u8 check;
+	int err;
+
+	err = sfp_read(sfp, false, 0, &id, sizeof(id));
+	if (err < 0) {
+		dev_err(sfp->dev, "failed to read EEPROM: %d\n", err);
+		return -EAGAIN;
+	}
+
+	if (err != sizeof(id)) {
+		dev_err(sfp->dev, "EEPROM short read: %d\n", err);
+		return -EAGAIN;
+	}
+
+	/* Validate the checksum over the base structure */
+	check = sfp_check(&id.base, sizeof(id.base) - 1);
+	if (check != id.base.cc_base) {
+		dev_err(sfp->dev,
+			"EEPROM base structure checksum failure: 0x%02x\n",
+			check);
+		print_hex_dump(KERN_ERR, "sfp EE: ", DUMP_PREFIX_OFFSET,
+			       16, 1, &id, sizeof(id.base) - 1, true);
+		return -EINVAL;
+	}
+
+	check = sfp_check(&id.ext, sizeof(id.ext) - 1);
+	if (check != id.ext.cc_ext) {
+		dev_err(sfp->dev,
+			"EEPROM extended structure checksum failure: 0x%02x\n",
+			check);
+		memset(&id.ext, 0, sizeof(id.ext));
+	}
+
+	sfp->id = id;
+
+	memcpy(vendor, sfp->id.base.vendor_name, 16);
+	vendor[16] = '\0';
+	memcpy(part, sfp->id.base.vendor_pn, 16);
+	part[16] = '\0';
+	memcpy(rev, sfp->id.base.vendor_rev, 4);
+	rev[4] = '\0';
+	memcpy(sn, sfp->id.ext.vendor_sn, 16);
+	sn[16] = '\0';
+	memcpy(date, sfp->id.ext.datecode, 8);
+	date[8] = '\0';
+
+	dev_info(sfp->dev, "module %s %s rev %s sn %s dc %s\n", vendor, part, rev, sn, date);
+
+	/* We only support SFP modules, not the legacy GBIC modules. */
+	if (sfp->id.base.phys_id != SFP_PHYS_ID_SFP ||
+	    sfp->id.base.phys_ext_id != SFP_PHYS_EXT_ID_SFP) {
+		dev_err(sfp->dev, "module is not SFP - phys id 0x%02x 0x%02x\n",
+			sfp->id.base.phys_id, sfp->id.base.phys_ext_id);
+		return -EINVAL;
+	}
+
+	return sfp_module_insert(sfp->sfp_bus, &sfp->id);
+}
+
+static void sfp_sm_mod_remove(struct sfp *sfp)
+{
+	sfp_module_remove(sfp->sfp_bus);
+
+	if (sfp->mod_phy)
+		sfp_sm_phy_detach(sfp);
+
+	sfp_module_tx_disable(sfp);
+
+	memset(&sfp->id, 0, sizeof(sfp->id));
+
+	dev_info(sfp->dev, "module removed\n");
+}
+
+static void sfp_sm_event(struct sfp *sfp, unsigned int event)
+{
+	mutex_lock(&sfp->sm_mutex);
+
+	dev_dbg(sfp->dev, "SM: enter %u:%u:%u event %u\n",
+		sfp->sm_mod_state, sfp->sm_dev_state, sfp->sm_state, event);
+
+	/* This state machine tracks the insert/remove state of
+	 * the module, and handles probing the on-board EEPROM.
+	 */
+	switch (sfp->sm_mod_state) {
+	default:
+		if (event == SFP_E_INSERT) {
+			sfp_module_tx_disable(sfp);
+			sfp_sm_ins_next(sfp, SFP_MOD_PROBE, T_PROBE_INIT);
+		}
+		break;
+
+	case SFP_MOD_PROBE:
+		if (event == SFP_E_REMOVE) {
+			sfp_sm_ins_next(sfp, SFP_MOD_EMPTY, 0);
+		} else if (event == SFP_E_TIMEOUT) {
+			int err = sfp_sm_mod_probe(sfp);
+
+			if (err == 0)
+				sfp_sm_ins_next(sfp, SFP_MOD_PRESENT, 0);
+			else if (err == -EAGAIN)
+				sfp_sm_set_timer(sfp, T_PROBE_RETRY);
+			else
+				sfp_sm_ins_next(sfp, SFP_MOD_ERROR, 0);
+		}
+		break;
+
+	case SFP_MOD_PRESENT:
+	case SFP_MOD_ERROR:
+		if (event == SFP_E_REMOVE) {
+			sfp_sm_mod_remove(sfp);
+			sfp_sm_ins_next(sfp, SFP_MOD_EMPTY, 0);
+		}
+		break;
+	}
+
+	/* This state machine tracks the netdev up/down state */
+	switch (sfp->sm_dev_state) {
+	default:
+		if (event == SFP_E_DEV_UP)
+			sfp->sm_dev_state = SFP_DEV_UP;
+		break;
+
+	case SFP_DEV_UP:
+		if (event == SFP_E_DEV_DOWN) {
+			/* If the module has a PHY, avoid raising TX disable
+			 * as this resets the PHY. Otherwise, raise it to
+			 * turn the laser off.
+			 */
+			if (!sfp->mod_phy)
+				sfp_module_tx_disable(sfp);
+			sfp->sm_dev_state = SFP_DEV_DOWN;
+		}
+		break;
+	}
+
+	/* Some events are global */
+	if (sfp->sm_state != SFP_S_DOWN &&
+	    (sfp->sm_mod_state != SFP_MOD_PRESENT ||
+	     sfp->sm_dev_state != SFP_DEV_UP)) {
+		if (sfp->sm_state == SFP_S_LINK_UP &&
+		    sfp->sm_dev_state == SFP_DEV_UP)
+			sfp_sm_link_down(sfp);
+		if (sfp->mod_phy)
+			sfp_sm_phy_detach(sfp);
+		sfp_sm_next(sfp, SFP_S_DOWN, 0);
+		mutex_unlock(&sfp->sm_mutex);
+		return;
+	}
+
+	/* The main state machine */
+	switch (sfp->sm_state) {
+	case SFP_S_DOWN:
+		if (sfp->sm_mod_state == SFP_MOD_PRESENT &&
+		    sfp->sm_dev_state == SFP_DEV_UP)
+			sfp_sm_mod_init(sfp);
+		break;
+
+	case SFP_S_INIT:
+		if (event == SFP_E_TIMEOUT && sfp->state & SFP_F_TX_FAULT)
+			sfp_sm_fault(sfp, true);
+		else if (event == SFP_E_TIMEOUT || event == SFP_E_TX_CLEAR)
+			sfp_sm_link_check_los(sfp);
+		break;
+
+	case SFP_S_WAIT_LOS:
+		if (event == SFP_E_TX_FAULT)
+			sfp_sm_fault(sfp, true);
+		else if (event ==
+			 (sfp->id.ext.options & SFP_OPTIONS_LOS_INVERTED ?
+			  SFP_E_LOS_HIGH : SFP_E_LOS_LOW))
+			sfp_sm_link_up(sfp);
+		break;
+
+	case SFP_S_LINK_UP:
+		if (event == SFP_E_TX_FAULT) {
+			sfp_sm_link_down(sfp);
+			sfp_sm_fault(sfp, true);
+		} else if (event ==
+			   (sfp->id.ext.options & SFP_OPTIONS_LOS_INVERTED ?
+			    SFP_E_LOS_LOW : SFP_E_LOS_HIGH)) {
+			sfp_sm_link_down(sfp);
+			sfp_sm_next(sfp, SFP_S_WAIT_LOS, 0);
+		}
+		break;
+
+	case SFP_S_TX_FAULT:
+		if (event == SFP_E_TIMEOUT) {
+			sfp_module_tx_fault_reset(sfp);
+			sfp_sm_next(sfp, SFP_S_REINIT, T_INIT_JIFFIES);
+		}
+		break;
+
+	case SFP_S_REINIT:
+		if (event == SFP_E_TIMEOUT && sfp->state & SFP_F_TX_FAULT) {
+			sfp_sm_fault(sfp, false);
+		} else if (event == SFP_E_TIMEOUT || event == SFP_E_TX_CLEAR) {
+			dev_info(sfp->dev, "module transmit fault recovered\n");
+			sfp_sm_link_check_los(sfp);
+		}
+		break;
+
+	case SFP_S_TX_DISABLE:
+		break;
+	}
+
+	dev_dbg(sfp->dev, "SM: exit %u:%u:%u\n",
+		sfp->sm_mod_state, sfp->sm_dev_state, sfp->sm_state);
+
+	mutex_unlock(&sfp->sm_mutex);
+}
+
+static void sfp_start(struct sfp *sfp)
+{
+	sfp_sm_event(sfp, SFP_E_DEV_UP);
+}
+
+static void sfp_stop(struct sfp *sfp)
+{
+	sfp_sm_event(sfp, SFP_E_DEV_DOWN);
+}
+
+static int sfp_module_info(struct sfp *sfp, struct ethtool_modinfo *modinfo)
+{
+	/* locking... and check module is present */
+
+	if (sfp->id.ext.sff8472_compliance) {
+		modinfo->type = ETH_MODULE_SFF_8472;
+		modinfo->eeprom_len = ETH_MODULE_SFF_8472_LEN;
+	} else {
+		modinfo->type = ETH_MODULE_SFF_8079;
+		modinfo->eeprom_len = ETH_MODULE_SFF_8079_LEN;
+	}
+	return 0;
+}
+
+static int sfp_module_eeprom(struct sfp *sfp, struct ethtool_eeprom *ee,
+	u8 *data)
+{
+	unsigned int first, last, len;
+	int ret;
+
+	if (ee->len == 0)
+		return -EINVAL;
+
+	first = ee->offset;
+	last = ee->offset + ee->len;
+	if (first < ETH_MODULE_SFF_8079_LEN) {
+		len = min_t(unsigned int, last, ETH_MODULE_SFF_8079_LEN);
+		len -= first;
+
+		ret = sfp->read(sfp, false, first, data, len);
+		if (ret < 0)
+			return ret;
+
+		first += len;
+		data += len;
+	}
+	if (first >= ETH_MODULE_SFF_8079_LEN &&
+	    first < ETH_MODULE_SFF_8472_LEN) {
+		len = min_t(unsigned int, last, ETH_MODULE_SFF_8472_LEN);
+		len -= first;
+		first -= ETH_MODULE_SFF_8079_LEN;
+
+		ret = sfp->read(sfp, true, first, data, len);
+		if (ret < 0)
+			return ret;
+	}
+	return 0;
+}
+
+static const struct sfp_socket_ops sfp_module_ops = {
+	.start = sfp_start,
+	.stop = sfp_stop,
+	.module_info = sfp_module_info,
+	.module_eeprom = sfp_module_eeprom,
+};
+
+static void sfp_timeout(struct work_struct *work)
+{
+	struct sfp *sfp = container_of(work, struct sfp, timeout.work);
+
+	rtnl_lock();
+	sfp_sm_event(sfp, SFP_E_TIMEOUT);
+	rtnl_unlock();
+}
+
+static void sfp_check_state(struct sfp *sfp)
+{
+	unsigned int state, i, changed;
+
+	state = sfp_get_state(sfp);
+	changed = state ^ sfp->state;
+	changed &= SFP_F_PRESENT | SFP_F_LOS | SFP_F_TX_FAULT;
+
+	for (i = 0; i < GPIO_MAX; i++)
+		if (changed & BIT(i))
+			dev_dbg(sfp->dev, "%s %u -> %u\n", gpio_of_names[i],
+				!!(sfp->state & BIT(i)), !!(state & BIT(i)));
+
+	state |= sfp->state & (SFP_F_TX_DISABLE | SFP_F_RATE_SELECT);
+	sfp->state = state;
+
+	rtnl_lock();
+	if (changed & SFP_F_PRESENT)
+		sfp_sm_event(sfp, state & SFP_F_PRESENT ?
+				SFP_E_INSERT : SFP_E_REMOVE);
+
+	if (changed & SFP_F_TX_FAULT)
+		sfp_sm_event(sfp, state & SFP_F_TX_FAULT ?
+				SFP_E_TX_FAULT : SFP_E_TX_CLEAR);
+
+	if (changed & SFP_F_LOS)
+		sfp_sm_event(sfp, state & SFP_F_LOS ?
+				SFP_E_LOS_HIGH : SFP_E_LOS_LOW);
+	rtnl_unlock();
+}
+
+static irqreturn_t sfp_irq(int irq, void *data)
+{
+	struct sfp *sfp = data;
+
+	sfp_check_state(sfp);
+
+	return IRQ_HANDLED;
+}
+
+static void sfp_poll(struct work_struct *work)
+{
+	struct sfp *sfp = container_of(work, struct sfp, poll.work);
+
+	sfp_check_state(sfp);
+	mod_delayed_work(system_wq, &sfp->poll, poll_jiffies);
+}
+
+static struct sfp *sfp_alloc(struct device *dev)
+{
+	struct sfp *sfp;
+
+	sfp = kzalloc(sizeof(*sfp), GFP_KERNEL);
+	if (!sfp)
+		return ERR_PTR(-ENOMEM);
+
+	sfp->dev = dev;
+
+	mutex_init(&sfp->sm_mutex);
+	INIT_DELAYED_WORK(&sfp->poll, sfp_poll);
+	INIT_DELAYED_WORK(&sfp->timeout, sfp_timeout);
+
+	return sfp;
+}
+
+static void sfp_cleanup(void *data)
+{
+	struct sfp *sfp = data;
+
+	cancel_delayed_work_sync(&sfp->poll);
+	cancel_delayed_work_sync(&sfp->timeout);
+	if (sfp->i2c_mii) {
+		mdiobus_unregister(sfp->i2c_mii);
+		mdiobus_free(sfp->i2c_mii);
+	}
+	if (sfp->i2c)
+		i2c_put_adapter(sfp->i2c);
+	kfree(sfp);
+}
+
+static int sfp_probe(struct platform_device *pdev)
+{
+	struct sfp *sfp;
+	bool poll = false;
+	int irq, err, i;
+
+	sfp = sfp_alloc(&pdev->dev);
+	if (IS_ERR(sfp))
+		return PTR_ERR(sfp);
+
+	platform_set_drvdata(pdev, sfp);
+
+	err = devm_add_action(sfp->dev, sfp_cleanup, sfp);
+	if (err < 0)
+		return err;
+
+	if (pdev->dev.of_node) {
+		struct device_node *node = pdev->dev.of_node;
+		struct device_node *np;
+
+		np = of_parse_phandle(node, "i2c-bus", 0);
+		if (np) {
+			struct i2c_adapter *i2c;
+
+			i2c = of_find_i2c_adapter_by_node(np);
+			of_node_put(np);
+			if (!i2c)
+				return -EPROBE_DEFER;
+
+			err = sfp_i2c_configure(sfp, i2c);
+			if (err < 0) {
+				i2c_put_adapter(i2c);
+				return err;
+			}
+		}
+
+		for (i = 0; i < GPIO_MAX; i++) {
+			sfp->gpio[i] = devm_gpiod_get_optional(sfp->dev,
+					   gpio_of_names[i], gpio_flags[i]);
+			if (IS_ERR(sfp->gpio[i]))
+				return PTR_ERR(sfp->gpio[i]);
+		}
+
+		sfp->get_state = sfp_gpio_get_state;
+		sfp->set_state = sfp_gpio_set_state;
+	}
+
+	sfp->sfp_bus = sfp_register_socket(sfp->dev, sfp, &sfp_module_ops);
+	if (!sfp->sfp_bus)
+		return -ENOMEM;
+
+	/* Get the initial state, and always signal TX disable,
+	 * since the network interface will not be up.
+	 */
+	sfp->state = sfp_get_state(sfp) | SFP_F_TX_DISABLE;
+
+	if (sfp->gpio[GPIO_RATE_SELECT] &&
+	    gpiod_get_value_cansleep(sfp->gpio[GPIO_RATE_SELECT]))
+		sfp->state |= SFP_F_RATE_SELECT;
+	sfp_set_state(sfp, sfp->state);
+	sfp_module_tx_disable(sfp);
+	rtnl_lock();
+	if (sfp->state & SFP_F_PRESENT)
+		sfp_sm_event(sfp, SFP_E_INSERT);
+	rtnl_unlock();
+
+	for (i = 0; i < GPIO_MAX; i++) {
+		if (gpio_flags[i] != GPIOD_IN || !sfp->gpio[i])
+			continue;
+
+		irq = gpiod_to_irq(sfp->gpio[i]);
+		if (!irq) {
+			poll = true;
+			continue;
+		}
+
+		err = devm_request_threaded_irq(sfp->dev, irq, NULL, sfp_irq,
+						IRQF_ONESHOT |
+						IRQF_TRIGGER_RISING |
+						IRQF_TRIGGER_FALLING,
+						dev_name(sfp->dev), sfp);
+		if (err)
+			poll = true;
+	}
+
+	if (poll)
+		mod_delayed_work(system_wq, &sfp->poll, poll_jiffies);
+
+	return 0;
+}
+
+static int sfp_remove(struct platform_device *pdev)
+{
+	struct sfp *sfp = platform_get_drvdata(pdev);
+
+	sfp_unregister_socket(sfp->sfp_bus);
+
+	return 0;
+}
+
+static const struct of_device_id sfp_of_match[] = {
+	{ .compatible = "sff,sfp", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, sfp_of_match);
+
+static struct platform_driver sfp_driver = {
+	.probe = sfp_probe,
+	.remove = sfp_remove,
+	.driver = {
+		.name = "sfp",
+		.of_match_table = sfp_of_match,
+	},
+};
+
+static int sfp_init(void)
+{
+	poll_jiffies = msecs_to_jiffies(100);
+
+	return platform_driver_register(&sfp_driver);
+}
+module_init(sfp_init);
+
+static void sfp_exit(void)
+{
+	platform_driver_unregister(&sfp_driver);
+}
+module_exit(sfp_exit);
+
+MODULE_ALIAS("platform:sfp");
+MODULE_AUTHOR("Russell King");
+MODULE_LICENSE("GPL v2");