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465 lines
12 KiB
465 lines
12 KiB
/* |
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* Multiplexed I2C bus driver. |
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* |
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* Copyright (c) 2008-2009 Rodolfo Giometti <[email protected]> |
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* Copyright (c) 2008-2009 Eurotech S.p.A. <[email protected]> |
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* Copyright (c) 2009-2010 NSN GmbH & Co KG <[email protected]> |
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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 <[email protected]> |
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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 <[email protected]> |
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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 <[email protected]>"); |
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MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses"); |
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MODULE_LICENSE("GPL v2");
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