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cfafa80b6e
We are using sysfs functions directly, so we should include the header. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Peter Rosin <peda@axentia.se>
466 lines
12 KiB
C
466 lines
12 KiB
C
/*
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* Multiplexed I2C bus driver.
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*
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* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
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* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
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* Copyright (c) 2009-2010 NSN GmbH & Co KG <michael.lawnick.ext@nsn.com>
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*
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* Simplifies access to complex multiplexed I2C bus topologies, by presenting
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* each multiplexed bus segment as an additional I2C adapter.
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* Supports multi-level mux'ing (mux behind a mux).
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*
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* Based on:
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* i2c-virt.c from Kumar Gala <galak@kernel.crashing.org>
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* i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
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* i2c-virtual.c from Brian Kuschak <bkuschak@yahoo.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/acpi.h>
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#include <linux/i2c.h>
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#include <linux/i2c-mux.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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/* multiplexer per channel data */
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struct i2c_mux_priv {
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struct i2c_adapter adap;
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struct i2c_algorithm algo;
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struct i2c_mux_core *muxc;
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u32 chan_id;
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};
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static int __i2c_mux_master_xfer(struct i2c_adapter *adap,
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struct i2c_msg msgs[], int num)
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{
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struct i2c_mux_priv *priv = adap->algo_data;
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struct i2c_mux_core *muxc = priv->muxc;
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struct i2c_adapter *parent = muxc->parent;
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int ret;
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/* Switch to the right mux port and perform the transfer. */
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ret = muxc->select(muxc, priv->chan_id);
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if (ret >= 0)
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ret = __i2c_transfer(parent, msgs, num);
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if (muxc->deselect)
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muxc->deselect(muxc, priv->chan_id);
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return ret;
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}
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static int i2c_mux_master_xfer(struct i2c_adapter *adap,
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struct i2c_msg msgs[], int num)
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{
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struct i2c_mux_priv *priv = adap->algo_data;
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struct i2c_mux_core *muxc = priv->muxc;
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struct i2c_adapter *parent = muxc->parent;
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int ret;
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/* Switch to the right mux port and perform the transfer. */
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ret = muxc->select(muxc, priv->chan_id);
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if (ret >= 0)
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ret = i2c_transfer(parent, msgs, num);
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if (muxc->deselect)
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muxc->deselect(muxc, priv->chan_id);
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return ret;
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}
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static int __i2c_mux_smbus_xfer(struct i2c_adapter *adap,
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u16 addr, unsigned short flags,
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char read_write, u8 command,
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int size, union i2c_smbus_data *data)
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{
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struct i2c_mux_priv *priv = adap->algo_data;
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struct i2c_mux_core *muxc = priv->muxc;
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struct i2c_adapter *parent = muxc->parent;
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int ret;
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/* Select the right mux port and perform the transfer. */
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ret = muxc->select(muxc, priv->chan_id);
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if (ret >= 0)
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ret = __i2c_smbus_xfer(parent, addr, flags,
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read_write, command, size, data);
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if (muxc->deselect)
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muxc->deselect(muxc, priv->chan_id);
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return ret;
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}
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static int i2c_mux_smbus_xfer(struct i2c_adapter *adap,
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u16 addr, unsigned short flags,
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char read_write, u8 command,
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int size, union i2c_smbus_data *data)
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{
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struct i2c_mux_priv *priv = adap->algo_data;
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struct i2c_mux_core *muxc = priv->muxc;
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struct i2c_adapter *parent = muxc->parent;
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int ret;
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/* Select the right mux port and perform the transfer. */
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ret = muxc->select(muxc, priv->chan_id);
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if (ret >= 0)
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ret = i2c_smbus_xfer(parent, addr, flags,
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read_write, command, size, data);
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if (muxc->deselect)
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muxc->deselect(muxc, priv->chan_id);
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return ret;
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}
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/* Return the parent's functionality */
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static u32 i2c_mux_functionality(struct i2c_adapter *adap)
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{
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struct i2c_mux_priv *priv = adap->algo_data;
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struct i2c_adapter *parent = priv->muxc->parent;
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return parent->algo->functionality(parent);
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}
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/* Return all parent classes, merged */
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static unsigned int i2c_mux_parent_classes(struct i2c_adapter *parent)
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{
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unsigned int class = 0;
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do {
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class |= parent->class;
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parent = i2c_parent_is_i2c_adapter(parent);
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} while (parent);
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return class;
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}
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static void i2c_mux_lock_bus(struct i2c_adapter *adapter, unsigned int flags)
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{
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struct i2c_mux_priv *priv = adapter->algo_data;
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struct i2c_adapter *parent = priv->muxc->parent;
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rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));
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if (!(flags & I2C_LOCK_ROOT_ADAPTER))
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return;
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i2c_lock_bus(parent, flags);
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}
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static int i2c_mux_trylock_bus(struct i2c_adapter *adapter, unsigned int flags)
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{
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struct i2c_mux_priv *priv = adapter->algo_data;
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struct i2c_adapter *parent = priv->muxc->parent;
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if (!rt_mutex_trylock(&parent->mux_lock))
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return 0; /* mux_lock not locked, failure */
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if (!(flags & I2C_LOCK_ROOT_ADAPTER))
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return 1; /* we only want mux_lock, success */
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if (i2c_trylock_bus(parent, flags))
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return 1; /* parent locked too, success */
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rt_mutex_unlock(&parent->mux_lock);
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return 0; /* parent not locked, failure */
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}
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static void i2c_mux_unlock_bus(struct i2c_adapter *adapter, unsigned int flags)
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{
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struct i2c_mux_priv *priv = adapter->algo_data;
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struct i2c_adapter *parent = priv->muxc->parent;
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if (flags & I2C_LOCK_ROOT_ADAPTER)
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i2c_unlock_bus(parent, flags);
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rt_mutex_unlock(&parent->mux_lock);
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}
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static void i2c_parent_lock_bus(struct i2c_adapter *adapter,
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unsigned int flags)
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{
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struct i2c_mux_priv *priv = adapter->algo_data;
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struct i2c_adapter *parent = priv->muxc->parent;
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rt_mutex_lock_nested(&parent->mux_lock, i2c_adapter_depth(adapter));
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i2c_lock_bus(parent, flags);
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}
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static int i2c_parent_trylock_bus(struct i2c_adapter *adapter,
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unsigned int flags)
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{
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struct i2c_mux_priv *priv = adapter->algo_data;
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struct i2c_adapter *parent = priv->muxc->parent;
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if (!rt_mutex_trylock(&parent->mux_lock))
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return 0; /* mux_lock not locked, failure */
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if (i2c_trylock_bus(parent, flags))
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return 1; /* parent locked too, success */
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rt_mutex_unlock(&parent->mux_lock);
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return 0; /* parent not locked, failure */
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}
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static void i2c_parent_unlock_bus(struct i2c_adapter *adapter,
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unsigned int flags)
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{
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struct i2c_mux_priv *priv = adapter->algo_data;
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struct i2c_adapter *parent = priv->muxc->parent;
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i2c_unlock_bus(parent, flags);
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rt_mutex_unlock(&parent->mux_lock);
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}
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struct i2c_adapter *i2c_root_adapter(struct device *dev)
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{
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struct device *i2c;
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struct i2c_adapter *i2c_root;
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/*
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* Walk up the device tree to find an i2c adapter, indicating
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* that this is an i2c client device. Check all ancestors to
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* handle mfd devices etc.
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*/
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for (i2c = dev; i2c; i2c = i2c->parent) {
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if (i2c->type == &i2c_adapter_type)
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break;
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}
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if (!i2c)
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return NULL;
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/* Continue up the tree to find the root i2c adapter */
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i2c_root = to_i2c_adapter(i2c);
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while (i2c_parent_is_i2c_adapter(i2c_root))
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i2c_root = i2c_parent_is_i2c_adapter(i2c_root);
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return i2c_root;
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}
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EXPORT_SYMBOL_GPL(i2c_root_adapter);
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struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
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struct device *dev, int max_adapters,
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int sizeof_priv, u32 flags,
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int (*select)(struct i2c_mux_core *, u32),
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int (*deselect)(struct i2c_mux_core *, u32))
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{
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struct i2c_mux_core *muxc;
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muxc = devm_kzalloc(dev, struct_size(muxc, adapter, max_adapters)
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+ sizeof_priv, GFP_KERNEL);
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if (!muxc)
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return NULL;
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if (sizeof_priv)
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muxc->priv = &muxc->adapter[max_adapters];
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muxc->parent = parent;
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muxc->dev = dev;
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if (flags & I2C_MUX_LOCKED)
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muxc->mux_locked = true;
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if (flags & I2C_MUX_ARBITRATOR)
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muxc->arbitrator = true;
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if (flags & I2C_MUX_GATE)
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muxc->gate = true;
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muxc->select = select;
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muxc->deselect = deselect;
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muxc->max_adapters = max_adapters;
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return muxc;
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}
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EXPORT_SYMBOL_GPL(i2c_mux_alloc);
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static const struct i2c_lock_operations i2c_mux_lock_ops = {
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.lock_bus = i2c_mux_lock_bus,
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.trylock_bus = i2c_mux_trylock_bus,
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.unlock_bus = i2c_mux_unlock_bus,
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};
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static const struct i2c_lock_operations i2c_parent_lock_ops = {
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.lock_bus = i2c_parent_lock_bus,
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.trylock_bus = i2c_parent_trylock_bus,
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.unlock_bus = i2c_parent_unlock_bus,
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};
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int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
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u32 force_nr, u32 chan_id,
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unsigned int class)
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{
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struct i2c_adapter *parent = muxc->parent;
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struct i2c_mux_priv *priv;
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char symlink_name[20];
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int ret;
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if (muxc->num_adapters >= muxc->max_adapters) {
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dev_err(muxc->dev, "No room for more i2c-mux adapters\n");
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return -EINVAL;
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}
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priv = kzalloc(sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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/* Set up private adapter data */
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priv->muxc = muxc;
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priv->chan_id = chan_id;
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/* Need to do algo dynamically because we don't know ahead
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* of time what sort of physical adapter we'll be dealing with.
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*/
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if (parent->algo->master_xfer) {
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if (muxc->mux_locked)
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priv->algo.master_xfer = i2c_mux_master_xfer;
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else
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priv->algo.master_xfer = __i2c_mux_master_xfer;
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}
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if (parent->algo->master_xfer_atomic)
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priv->algo.master_xfer_atomic = priv->algo.master_xfer;
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if (parent->algo->smbus_xfer) {
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if (muxc->mux_locked)
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priv->algo.smbus_xfer = i2c_mux_smbus_xfer;
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else
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priv->algo.smbus_xfer = __i2c_mux_smbus_xfer;
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}
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if (parent->algo->smbus_xfer_atomic)
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priv->algo.smbus_xfer_atomic = priv->algo.smbus_xfer;
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priv->algo.functionality = i2c_mux_functionality;
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/* Now fill out new adapter structure */
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snprintf(priv->adap.name, sizeof(priv->adap.name),
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"i2c-%d-mux (chan_id %d)", i2c_adapter_id(parent), chan_id);
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priv->adap.owner = THIS_MODULE;
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priv->adap.algo = &priv->algo;
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priv->adap.algo_data = priv;
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priv->adap.dev.parent = &parent->dev;
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priv->adap.retries = parent->retries;
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priv->adap.timeout = parent->timeout;
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priv->adap.quirks = parent->quirks;
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if (muxc->mux_locked)
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priv->adap.lock_ops = &i2c_mux_lock_ops;
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else
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priv->adap.lock_ops = &i2c_parent_lock_ops;
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/* Sanity check on class */
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if (i2c_mux_parent_classes(parent) & class)
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dev_err(&parent->dev,
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"Segment %d behind mux can't share classes with ancestors\n",
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chan_id);
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else
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priv->adap.class = class;
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/*
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* Try to populate the mux adapter's of_node, expands to
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* nothing if !CONFIG_OF.
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*/
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if (muxc->dev->of_node) {
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struct device_node *dev_node = muxc->dev->of_node;
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struct device_node *mux_node, *child = NULL;
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u32 reg;
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if (muxc->arbitrator)
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mux_node = of_get_child_by_name(dev_node, "i2c-arb");
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else if (muxc->gate)
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mux_node = of_get_child_by_name(dev_node, "i2c-gate");
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else
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mux_node = of_get_child_by_name(dev_node, "i2c-mux");
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if (mux_node) {
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/* A "reg" property indicates an old-style DT entry */
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if (!of_property_read_u32(mux_node, "reg", ®)) {
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of_node_put(mux_node);
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mux_node = NULL;
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}
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}
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if (!mux_node)
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mux_node = of_node_get(dev_node);
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else if (muxc->arbitrator || muxc->gate)
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child = of_node_get(mux_node);
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if (!child) {
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for_each_child_of_node(mux_node, child) {
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ret = of_property_read_u32(child, "reg", ®);
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if (ret)
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continue;
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if (chan_id == reg)
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break;
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}
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}
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priv->adap.dev.of_node = child;
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of_node_put(mux_node);
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}
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/*
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* Associate the mux channel with an ACPI node.
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*/
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if (has_acpi_companion(muxc->dev))
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acpi_preset_companion(&priv->adap.dev,
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ACPI_COMPANION(muxc->dev),
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chan_id);
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if (force_nr) {
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priv->adap.nr = force_nr;
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ret = i2c_add_numbered_adapter(&priv->adap);
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if (ret < 0) {
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dev_err(&parent->dev,
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"failed to add mux-adapter %u as bus %u (error=%d)\n",
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chan_id, force_nr, ret);
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goto err_free_priv;
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}
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} else {
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ret = i2c_add_adapter(&priv->adap);
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if (ret < 0) {
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dev_err(&parent->dev,
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"failed to add mux-adapter %u (error=%d)\n",
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chan_id, ret);
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goto err_free_priv;
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}
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}
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WARN(sysfs_create_link(&priv->adap.dev.kobj, &muxc->dev->kobj,
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"mux_device"),
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"can't create symlink to mux device\n");
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snprintf(symlink_name, sizeof(symlink_name), "channel-%u", chan_id);
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WARN(sysfs_create_link(&muxc->dev->kobj, &priv->adap.dev.kobj,
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symlink_name),
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"can't create symlink to channel %u\n", chan_id);
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dev_info(&parent->dev, "Added multiplexed i2c bus %d\n",
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i2c_adapter_id(&priv->adap));
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muxc->adapter[muxc->num_adapters++] = &priv->adap;
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return 0;
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err_free_priv:
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kfree(priv);
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return ret;
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}
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EXPORT_SYMBOL_GPL(i2c_mux_add_adapter);
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void i2c_mux_del_adapters(struct i2c_mux_core *muxc)
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{
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char symlink_name[20];
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while (muxc->num_adapters) {
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struct i2c_adapter *adap = muxc->adapter[--muxc->num_adapters];
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struct i2c_mux_priv *priv = adap->algo_data;
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struct device_node *np = adap->dev.of_node;
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muxc->adapter[muxc->num_adapters] = NULL;
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snprintf(symlink_name, sizeof(symlink_name),
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"channel-%u", priv->chan_id);
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sysfs_remove_link(&muxc->dev->kobj, symlink_name);
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sysfs_remove_link(&priv->adap.dev.kobj, "mux_device");
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i2c_del_adapter(adap);
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of_node_put(np);
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kfree(priv);
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}
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}
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EXPORT_SYMBOL_GPL(i2c_mux_del_adapters);
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MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
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MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
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MODULE_LICENSE("GPL v2");
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