1 files changed, 459 insertions, 0 deletions

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
new file mode 100644
index 000000000..f330690b4
--- /dev/null
+++ b/drivers/i2c/i2c-mux.c
@@ -0,0 +1,459 @@
+/*
+ * Multiplexed I2C bus driver.
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ * Copyright (c) 2009-2010 NSN GmbH & Co KG <michael.lawnick.ext@nsn.com>
+ *
+ * Simplifies access to complex multiplexed I2C bus topologies, by presenting
+ * each multiplexed bus segment as an additional I2C adapter.
+ * Supports multi-level mux'ing (mux behind a mux).
+ *
+ * Based on:
+ *	i2c-virt.c from Kumar Gala <galak@kernel.crashing.org>
+ *	i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
+ *	i2c-virtual.c from Brian Kuschak <bkuschak@yahoo.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/acpi.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+/* multiplexer per channel data */
+struct i2c_mux_priv {
+	struct i2c_adapter adap;
+	struct i2c_algorithm algo;
+	struct i2c_mux_core *muxc;
+	u32 chan_id;
+};
+
+static int __i2c_mux_master_xfer(struct i2c_adapter *adap,
+				 struct i2c_msg msgs[], int num)
+{
+	struct i2c_mux_priv *priv = adap->algo_data;
+	struct i2c_mux_core *muxc = priv->muxc;
+	struct i2c_adapter *parent = muxc->parent;
+	int ret;
+
+	/* Switch to the right mux port and perform the transfer. */
+
+	ret = muxc->select(muxc, priv->chan_id);
+	if (ret >= 0)
+		ret = __i2c_transfer(parent, msgs, num);
+	if (muxc->deselect)
+		muxc->deselect(muxc, priv->chan_id);
+
+	return ret;
+}
+
+static int i2c_mux_master_xfer(struct i2c_adapter *adap,
+			       struct i2c_msg msgs[], int num)
+{
+	struct i2c_mux_priv *priv = adap->algo_data;
+	struct i2c_mux_core *muxc = priv->muxc;
+	struct i2c_adapter *parent = muxc->parent;
+	int ret;
+
+	/* Switch to the right mux port and perform the transfer. */
+
+	ret = muxc->select(muxc, priv->chan_id);
+	if (ret >= 0)
+		ret = i2c_transfer(parent, msgs, num);
+	if (muxc->deselect)
+		muxc->deselect(muxc, priv->chan_id);
+
+	return ret;
+}
+
+static int __i2c_mux_smbus_xfer(struct i2c_adapter *adap,
+				u16 addr, unsigned short flags,
+				char read_write, u8 command,
+				int size, union i2c_smbus_data *data)
+{
+	struct i2c_mux_priv *priv = adap->algo_data;
+	struct i2c_mux_core *muxc = priv->muxc;
+	struct i2c_adapter *parent = muxc->parent;
+	int ret;
+
+	/* Select the right mux port and perform the transfer. */
+
+	ret = muxc->select(muxc, priv->chan_id);
+	if (ret >= 0)
+		ret = __i2c_smbus_xfer(parent, addr, flags,
+				       read_write, command, size, data);
+	if (muxc->deselect)
+		muxc->deselect(muxc, priv->chan_id);
+
+	return ret;
+}
+
+static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
+			      u16 addr, unsigned short flags,
+			      char read_write, u8 command,
+			      int size, union i2c_smbus_data *data)
+{
+	struct i2c_mux_priv *priv = adap->algo_data;
+	struct i2c_mux_core *muxc = priv->muxc;
+	struct i2c_adapter *parent = muxc->parent;
+	int ret;
+
+	/* Select the right mux port and perform the transfer. */
+
+	ret = muxc->select(muxc, priv->chan_id);
+	if (ret >= 0)
+		ret = i2c_smbus_xfer(parent, addr, flags,
+				     read_write, command, size, data);
+	if (muxc->deselect)
+		muxc->deselect(muxc, priv->chan_id);
+
+	return ret;
+}
+
+/* Return the parent's functionality */
+static u32 i2c_mux_functionality(struct i2c_adapter *adap)
+{
+	struct i2c_mux_priv *priv = adap->algo_data;
+	struct i2c_adapter *parent = priv->muxc->parent;
+
+	return parent->algo->functionality(parent);
+}
+
+/* Return all parent classes, merged */
+static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
+{
+	unsigned int class = 0;
+
+	do {
+		class |= parent->class;
+		parent = i2c_parent_is_i2c_adapter(parent);
+	} while (parent);
+
+	return class;
+}
+
+static void i2c_mux_lock_bus(struct i2c_adapter *adapter, unsigned int flags)
+{
+	struct i2c_mux_priv *priv = adapter->algo_data;
+	struct i2c_adapter *parent = priv->muxc->parent;
+
+	rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));
+	if (!(flags & I2C_LOCK_ROOT_ADAPTER))
+		return;
+	i2c_lock_bus(parent, flags);
+}
+
+static int i2c_mux_trylock_bus(struct i2c_adapter *adapter, unsigned int flags)
+{
+	struct i2c_mux_priv *priv = adapter->algo_data;
+	struct i2c_adapter *parent = priv->muxc->parent;
+
+	if (!rt_mutex_trylock(&parent->mux_lock))
+		return 0;	/* mux_lock not locked, failure */
+	if (!(flags & I2C_LOCK_ROOT_ADAPTER))
+		return 1;	/* we only want mux_lock, success */
+	if (i2c_trylock_bus(parent, flags))
+		return 1;	/* parent locked too, success */
+	rt_mutex_unlock(&parent->mux_lock);
+	return 0;		/* parent not locked, failure */
+}
+
+static void i2c_mux_unlock_bus(struct i2c_adapter *adapter, unsigned int flags)
+{
+	struct i2c_mux_priv *priv = adapter->algo_data;
+	struct i2c_adapter *parent = priv->muxc->parent;
+
+	if (flags & I2C_LOCK_ROOT_ADAPTER)
+		i2c_unlock_bus(parent, flags);
+	rt_mutex_unlock(&parent->mux_lock);
+}
+
+static void i2c_parent_lock_bus(struct i2c_adapter *adapter,
+				unsigned int flags)
+{
+	struct i2c_mux_priv *priv = adapter->algo_data;
+	struct i2c_adapter *parent = priv->muxc->parent;
+
+	rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));
+	i2c_lock_bus(parent, flags);
+}
+
+static int i2c_parent_trylock_bus(struct i2c_adapter *adapter,
+				  unsigned int flags)
+{
+	struct i2c_mux_priv *priv = adapter->algo_data;
+	struct i2c_adapter *parent = priv->muxc->parent;
+
+	if (!rt_mutex_trylock(&parent->mux_lock))
+		return 0;	/* mux_lock not locked, failure */
+	if (i2c_trylock_bus(parent, flags))
+		return 1;	/* parent locked too, success */
+	rt_mutex_unlock(&parent->mux_lock);
+	return 0;		/* parent not locked, failure */
+}
+
+static void i2c_parent_unlock_bus(struct i2c_adapter *adapter,
+				  unsigned int flags)
+{
+	struct i2c_mux_priv *priv = adapter->algo_data;
+	struct i2c_adapter *parent = priv->muxc->parent;
+
+	i2c_unlock_bus(parent, flags);
+	rt_mutex_unlock(&parent->mux_lock);
+}
+
+struct i2c_adapter *i2c_root_adapter(struct device *dev)
+{
+	struct device *i2c;
+	struct i2c_adapter *i2c_root;
+
+	/*
+	 * Walk up the device tree to find an i2c adapter, indicating
+	 * that this is an i2c client device. Check all ancestors to
+	 * handle mfd devices etc.
+	 */
+	for (i2c = dev; i2c; i2c = i2c->parent) {
+		if (i2c->type == &i2c_adapter_type)
+			break;
+	}
+	if (!i2c)
+		return NULL;
+
+	/* Continue up the tree to find the root i2c adapter */
+	i2c_root = to_i2c_adapter(i2c);
+	while (i2c_parent_is_i2c_adapter(i2c_root))
+		i2c_root = i2c_parent_is_i2c_adapter(i2c_root);
+
+	return i2c_root;
+}
+EXPORT_SYMBOL_GPL(i2c_root_adapter);
+
+struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
+				   struct device *dev, int max_adapters,
+				   int sizeof_priv, u32 flags,
+				   int (*select)(struct i2c_mux_core *, u32),
+				   int (*deselect)(struct i2c_mux_core *, u32))
+{
+	struct i2c_mux_core *muxc;
+
+	muxc = devm_kzalloc(dev, sizeof(*muxc)
+			    + max_adapters * sizeof(muxc->adapter[0])
+			    + sizeof_priv, GFP_KERNEL);
+	if (!muxc)
+		return NULL;
+	if (sizeof_priv)
+		muxc->priv = &muxc->adapter[max_adapters];
+
+	muxc->parent = parent;
+	muxc->dev = dev;
+	if (flags & I2C_MUX_LOCKED)
+		muxc->mux_locked = true;
+	if (flags & I2C_MUX_ARBITRATOR)
+		muxc->arbitrator = true;
+	if (flags & I2C_MUX_GATE)
+		muxc->gate = true;
+	muxc->select = select;
+	muxc->deselect = deselect;
+	muxc->max_adapters = max_adapters;
+
+	return muxc;
+}
+EXPORT_SYMBOL_GPL(i2c_mux_alloc);
+
+static const struct i2c_lock_operations i2c_mux_lock_ops = {
+	.lock_bus =    i2c_mux_lock_bus,
+	.trylock_bus = i2c_mux_trylock_bus,
+	.unlock_bus =  i2c_mux_unlock_bus,
+};
+
+static const struct i2c_lock_operations i2c_parent_lock_ops = {
+	.lock_bus =    i2c_parent_lock_bus,
+	.trylock_bus = i2c_parent_trylock_bus,
+	.unlock_bus =  i2c_parent_unlock_bus,
+};
+
+int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
+			u32 force_nr, u32 chan_id,
+			unsigned int class)
+{
+	struct i2c_adapter *parent = muxc->parent;
+	struct i2c_mux_priv *priv;
+	char symlink_name[20];
+	int ret;
+
+	if (muxc->num_adapters >= muxc->max_adapters) {
+		dev_err(muxc->dev, "No room for more i2c-mux adapters\n");
+		return -EINVAL;
+	}
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	/* Set up private adapter data */
+	priv->muxc = muxc;
+	priv->chan_id = chan_id;
+
+	/* Need to do algo dynamically because we don't know ahead
+	 * of time what sort of physical adapter we'll be dealing with.
+	 */
+	if (parent->algo->master_xfer) {
+		if (muxc->mux_locked)
+			priv->algo.master_xfer = i2c_mux_master_xfer;
+		else
+			priv->algo.master_xfer = __i2c_mux_master_xfer;
+	}
+	if (parent->algo->smbus_xfer) {
+		if (muxc->mux_locked)
+			priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
+		else
+			priv->algo.smbus_xfer = __i2c_mux_smbus_xfer;
+	}
+	priv->algo.functionality = i2c_mux_functionality;
+
+	/* Now fill out new adapter structure */
+	snprintf(priv->adap.name, sizeof(priv->adap.name),
+		 "i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
+	priv->adap.owner = THIS_MODULE;
+	priv->adap.algo = &priv->algo;
+	priv->adap.algo_data = priv;
+	priv->adap.dev.parent = &parent->dev;
+	priv->adap.retries = parent->retries;
+	priv->adap.timeout = parent->timeout;
+	priv->adap.quirks = parent->quirks;
+	if (muxc->mux_locked)
+		priv->adap.lock_ops = &i2c_mux_lock_ops;
+	else
+		priv->adap.lock_ops = &i2c_parent_lock_ops;
+
+	/* Sanity check on class */
+	if (i2c_mux_parent_classes(parent) & class)
+		dev_err(&parent->dev,
+			"Segment %d behind mux can't share classes with ancestors\n",
+			chan_id);
+	else
+		priv->adap.class = class;
+
+	/*
+	 * Try to populate the mux adapter's of_node, expands to
+	 * nothing if !CONFIG_OF.
+	 */
+	if (muxc->dev->of_node) {
+		struct device_node *dev_node = muxc->dev->of_node;
+		struct device_node *mux_node, *child = NULL;
+		u32 reg;
+
+		if (muxc->arbitrator)
+			mux_node = of_get_child_by_name(dev_node, "i2c-arb");
+		else if (muxc->gate)
+			mux_node = of_get_child_by_name(dev_node, "i2c-gate");
+		else
+			mux_node = of_get_child_by_name(dev_node, "i2c-mux");
+
+		if (mux_node) {
+			/* A "reg" property indicates an old-style DT entry */
+			if (!of_property_read_u32(mux_node, "reg", &reg)) {
+				of_node_put(mux_node);
+				mux_node = NULL;
+			}
+		}
+
+		if (!mux_node)
+			mux_node = of_node_get(dev_node);
+		else if (muxc->arbitrator || muxc->gate)
+			child = of_node_get(mux_node);
+
+		if (!child) {
+			for_each_child_of_node(mux_node, child) {
+				ret = of_property_read_u32(child, "reg", &reg);
+				if (ret)
+					continue;
+				if (chan_id == reg)
+					break;
+			}
+		}
+
+		priv->adap.dev.of_node = child;
+		of_node_put(mux_node);
+	}
+
+	/*
+	 * Associate the mux channel with an ACPI node.
+	 */
+	if (has_acpi_companion(muxc->dev))
+		acpi_preset_companion(&priv->adap.dev,
+				      ACPI_COMPANION(muxc->dev),
+				      chan_id);
+
+	if (force_nr) {
+		priv->adap.nr = force_nr;
+		ret = i2c_add_numbered_adapter(&priv->adap);
+		if (ret < 0) {
+			dev_err(&parent->dev,
+				"failed to add mux-adapter %u as bus %u (error=%d)\n",
+				chan_id, force_nr, ret);
+			goto err_free_priv;
+		}
+	} else {
+		ret = i2c_add_adapter(&priv->adap);
+		if (ret < 0) {
+			dev_err(&parent->dev,
+				"failed to add mux-adapter %u (error=%d)\n",
+				chan_id, ret);
+			goto err_free_priv;
+		}
+	}
+
+	WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj,
+			       "mux_device"),
+	     "can't create symlink to mux device\n");
+
+	snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
+	WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj,
+			       symlink_name),
+	     "can't create symlink to channel %u\n", chan_id);
+	dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
+		 i2c_adapter_id(&priv->adap));
+
+	muxc->adapter[muxc->num_adapters++] = &priv->adap;
+	return 0;
+
+err_free_priv:
+	kfree(priv);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_mux_add_adapter);
+
+void i2c_mux_del_adapters(struct i2c_mux_core *muxc)
+{
+	char symlink_name[20];
+
+	while (muxc->num_adapters) {
+		struct i2c_adapter *adap = muxc->adapter[--muxc->num_adapters];
+		struct i2c_mux_priv *priv = adap->algo_data;
+		struct device_node *np = adap->dev.of_node;
+
+		muxc->adapter[muxc->num_adapters] = NULL;
+
+		snprintf(symlink_name, sizeof(symlink_name),
+			 "channel-%u", priv->chan_id);
+		sysfs_remove_link(&muxc->dev->kobj, symlink_name);
+
+		sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
+		i2c_del_adapter(adap);
+		of_node_put(np);
+		kfree(priv);
+	}
+}
+EXPORT_SYMBOL_GPL(i2c_mux_del_adapters);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
+MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
+MODULE_LICENSE("GPL v2");