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-rw-r--r--drivers/i2c/i2c-mux.c466
1 files changed, 466 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
new file mode 100644
index 000000000..57ff09f18
--- /dev/null
+++ b/drivers/i2c/i2c-mux.c
@@ -0,0 +1,466 @@
+/*
+ * 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>
+#include <linux/sysfs.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;
+ size_t mux_size;
+
+ mux_size = struct_size(muxc, adapter, max_adapters);
+ muxc = devm_kzalloc(dev, size_add(mux_size, 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->master_xfer_atomic)
+ priv->algo.master_xfer_atomic = priv->algo.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;
+ }
+ if (parent->algo->smbus_xfer_atomic)
+ priv->algo.smbus_xfer_atomic = priv->algo.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 & ~I2C_CLASS_DEPRECATED)
+ 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");