* [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
@ 2010-05-04 12:46 Michael Lawnick
[not found] ` <4BE01741.1010909-Mmb7MZpHnFY@public.gmane.org>
0 siblings, 1 reply; 20+ messages in thread
From: Michael Lawnick @ 2010-05-04 12:46 UTC (permalink / raw)
To: Linux I2C; +Cc: Delvare, Jean , Rodolfo Giometti
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[-- Attachment #2: 0001-mux_core_support.patch --]
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Add multiplexed bus core support. I2C multiplexer and switches
like pca954x get instantiated as new adapters per output.
Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
---
Based on kernel 2.6.33 +
[PATCH] i2c-core: Use per-adapter userspace device lists
by Jean Delware <20100424201914.08b3f008-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
<http://article.gmane.org/gmane.linux.drivers.i2c/5994/>
drivers/i2c/Kconfig | 8 ++
drivers/i2c/Makefile | 1 +
drivers/i2c/i2c-core.c | 93 ++++++++++++++++++++++--
drivers/i2c/i2c-dev.c | 46 ++++++++++++-
drivers/i2c/i2c-mux.c | 184 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/i2c-mux.h | 46 ++++++++++++
include/linux/i2c.h | 11 +++
7 files changed, 381 insertions(+), 8 deletions(-)
create mode 100755 drivers/i2c/i2c-mux.c
create mode 100755 include/linux/i2c-mux.h
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 8d8a00e..2cd6d78 100755
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -36,6 +36,14 @@ config I2C_COMPAT
other user-space package which expects i2c adapters to be class
devices. If you don't know, say Y.
+config I2C_MUX
+ tristate "I2C bus multiplexing support"
+ depends on I2C
+ help
+ Say Y here if you want the I2C core to support the ability to
+ handle multiplexed I2C bus topologies, by presenting each
+ multiplexed segment as a I2C adapter.
+
config I2C_CHARDEV
tristate "I2C device interface"
help
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index ba26e6c..a488e8b 100755
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -5,6 +5,7 @@
obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
obj-$(CONFIG_I2C) += i2c-core.o
obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
+obj-$(CONFIG_I2C_MUX) += i2c-mux.o
obj-y += busses/ chips/ algos/
ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index fc93e28..682966a 100755
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -20,7 +20,10 @@
/* With some changes from Kyösti Mälkki <kmalkki-kf+aQKke1yb1KXRcyAk9cg@public.gmane.org>.
All SMBus-related things are written by Frodo Looijaard <frodol-B0qZmFHriGg@public.gmane.org>
SMBus 2.0 support by Mark Studebaker <mdsxyz123-/E1597aS9LQAvxtiuMwx3w@public.gmane.org> and
- Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org> */
+ Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
+ Mux support by Rodolfo Giometti <giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org> and
+ Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org> */
+
#include <linux/module.h>
#include <linux/kernel.h>
@@ -288,6 +291,12 @@ struct i2c_client *i2c_verify_client(struct device *dev)
}
EXPORT_SYMBOL(i2c_verify_client);
+static int i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
+{
+ return adapter->dev.parent != NULL
+ && adapter->dev.parent->bus == &i2c_bus_type;
+}
+
/**
* i2c_new_device - instantiate an i2c device
@@ -624,6 +633,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
rt_mutex_init(&adap->bus_lock);
INIT_LIST_HEAD(&adap->userspace_clients);
+ INIT_LIST_HEAD(&adap->mux_list_head);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
@@ -949,9 +959,78 @@ static int __i2c_check_addr(struct device *dev, void *addrp)
return 0;
}
+/* walk up mux tree */
+static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+ int result;
+
+ result = device_for_each_child(&adapter->dev, &addr, __i2c_check_addr);
+
+ if (!result && i2c_parent_is_i2c_adapter(adapter))
+ result = i2c_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ return result;
+}
+
+/* recurse down mux tree */
+static int i2c_check_mux_childs(struct i2c_adapter *adapter, int addr)
+{
+ int result = 0;
+ struct i2c_adapter *child, *next;
+
+ list_for_each_entry_safe(child, next, &adapter->mux_list_head,
+ mux_list) {
+ result = device_for_each_child(&child->dev, &addr,
+ __i2c_check_addr);
+ if (result)
+ break;
+ result = i2c_check_mux_childs(child, addr);
+ }
+ return result;
+}
+
static int i2c_check_addr(struct i2c_adapter *adapter, int addr)
{
- return device_for_each_child(&adapter->dev, &addr, __i2c_check_addr);
+ int result;
+
+ result = i2c_check_mux_parents(adapter, addr);
+
+ if (!result)
+ result = i2c_check_mux_childs(adapter, addr);
+
+ return result;
+}
+
+static void i2c_mux_tree_lock(struct i2c_adapter *adap)
+{
+ if (i2c_parent_is_i2c_adapter(adap))
+ i2c_mux_tree_lock(to_i2c_adapter(adap->dev.parent));
+ else
+ i2c_lock_adapter(adap);
+}
+
+static int i2c_mux_tree_trylock(struct i2c_adapter *adap)
+{
+ int ret;
+ struct i2c_adapter *parent;
+
+ if (i2c_parent_is_i2c_adapter(adap)) {
+ parent = to_i2c_adapter(adap->dev.parent);
+ ret = i2c_mux_tree_trylock(parent);
+ } else {
+ ret = i2c_trylock_adapter(adap);
+ }
+
+ return ret;
+}
+
+static void i2c_mux_tree_unlock(struct i2c_adapter *adap)
+{
+ if (i2c_parent_is_i2c_adapter(adap))
+ i2c_mux_tree_unlock(to_i2c_adapter(adap->dev.parent));
+ else
+ i2c_unlock_adapter(adap);
}
/**
@@ -1104,12 +1183,12 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
#endif
if (in_atomic() || irqs_disabled()) {
- ret = rt_mutex_trylock(&adap->bus_lock);
+ ret = i2c_mux_tree_trylock(adap);
if (!ret)
/* I2C activity is ongoing. */
return -EAGAIN;
} else {
- rt_mutex_lock(&adap->bus_lock);
+ i2c_mux_tree_lock(adap);
}
/* Retry automatically on arbitration loss */
@@ -1121,7 +1200,7 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
if (time_after(jiffies, orig_jiffies + adap->timeout))
break;
}
- rt_mutex_unlock(&adap->bus_lock);
+ i2c_mux_tree_unlock(adap);
return ret;
} else {
@@ -1857,7 +1936,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
flags &= I2C_M_TEN | I2C_CLIENT_PEC;
if (adapter->algo->smbus_xfer) {
- rt_mutex_lock(&adapter->bus_lock);
+ i2c_mux_tree_lock(adapter);
/* Retry automatically on arbitration loss */
orig_jiffies = jiffies;
@@ -1871,7 +1950,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
orig_jiffies + adapter->timeout))
break;
}
- rt_mutex_unlock(&adapter->bus_lock);
+ i2c_mux_tree_unlock(adapter);
} else
res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
command, protocol, data);
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index f4110aa..da5327f 100755
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -193,12 +193,56 @@ static int i2cdev_check(struct device *dev, void *addrp)
return dev->driver ? -EBUSY : 0;
}
+static int i2cdev_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
+{
+ return adapter->dev.parent != NULL
+ && adapter->dev.parent->bus == &i2c_bus_type;
+}
+
+/* walk up mux tree */
+static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+ int result;
+
+ result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+
+ if (!result && i2cdev_parent_is_i2c_adapter(adapter))
+ result = i2cdev_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ return result;
+}
+
+/* recurse down mux tree */
+static int i2cdev_check_mux_childs(struct i2c_adapter *adapter, int addr)
+{
+ int result = 0;
+ struct i2c_adapter *child, *next;
+
+ list_for_each_entry_safe(child, next, &adapter->mux_list_head,
+ mux_list) {
+ result = device_for_each_child(&child->dev, &addr,
+ i2cdev_check);
+ if (result)
+ break;
+ result = i2cdev_check_mux_childs(child, addr);
+ }
+ return result;
+}
+
/* This address checking function differs from the one in i2c-core
in that it considers an address with a registered device, but no
driver bound to it, as NOT busy. */
static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
{
- return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+ int result;
+
+ result = i2cdev_check_mux_parents(adapter, addr);
+
+ if (!result)
+ result = i2cdev_check_mux_childs(adapter, addr);
+
+ return result;
}
static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
new file mode 100755
index 0000000..f88d29a
--- /dev/null
+++ b/drivers/i2c/i2c-mux.c
@@ -0,0 +1,184 @@
+/*
+ * Multiplexed I2C bus driver.
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
+ *
+ * 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-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
+ * i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
+ * i2c-virtual.c from Brian Kuschak <bkuschak-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>
+ *
+ * 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.
+ */
+
+/* Adapted to kernel 2.6.33 by Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org> */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+
+/* multiplexer per channel data */
+struct i2c_mux_priv {
+ struct i2c_adapter adap;
+ struct i2c_algorithm algo;
+
+ struct i2c_adapter *parent;
+ void *mux_dev; /* the mux chip/device */
+ u32 chan_id; /* the channel id */
+
+ int (*select)(struct i2c_adapter *adap, void *mux_dev, u32 chan_id);
+ int (*deselect)(struct i2c_adapter *adap, void *mux_dev, u32 chan_id);
+};
+
+#define VIRT_TIMEOUT (HZ/2)
+#define VIRT_RETRIES 3
+
+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_adapter *parent = priv->parent;
+ int ret;
+
+ /* Switch to the right mux port and perform the transfer.*/
+
+ ret = priv->select(parent, priv->mux_dev, priv->chan_id);
+ if (ret >= 0)
+ ret = parent->algo->master_xfer(parent, msgs, num);
+ if (priv->deselect)
+ priv->deselect(parent, priv->mux_dev, 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_adapter *parent = priv->parent;
+ int ret;
+
+ /* Select the right mux port and perform the transfer.*/
+
+ ret = priv->select(parent, priv->mux_dev, priv->chan_id);
+ if (ret >= 0)
+ ret = parent->algo->smbus_xfer(parent, addr, flags,
+ read_write, command, size, data);
+ if (priv->deselect)
+ priv->deselect(parent, priv->mux_dev, priv->chan_id);
+
+ return ret;
+}
+
+/* Return the parent's functionality for the virtual adapter */
+static u32 i2c_mux_functionality(struct i2c_adapter *adap)
+{
+ struct i2c_mux_priv *priv = adap->algo_data;
+ struct i2c_adapter *parent = priv->parent;
+
+ return parent->algo->functionality(parent);
+}
+
+struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
+ void *mux_dev, u32 force_nr, u32 chan_id,
+ int (*select) (struct i2c_adapter *,
+ void *, u32),
+ int (*deselect) (struct i2c_adapter *,
+ void *, u32))
+{
+ struct i2c_mux_priv *priv;
+ int ret;
+
+ priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
+ if (!priv)
+ return NULL;
+
+ /* Set up private adapter data */
+ priv->parent = parent;
+ priv->mux_dev = mux_dev;
+ priv->chan_id = chan_id;
+ priv->select = select;
+ priv->deselect = deselect;
+
+ /* 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)
+ priv->algo.master_xfer = i2c_mux_master_xfer;
+ if (parent->algo->smbus_xfer)
+ 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.id = parent->id;
+ priv->adap.algo = &priv->algo;
+ priv->adap.algo_data = priv;
+ priv->adap.dev.parent = &parent->dev;
+
+ if (force_nr) {
+ priv->adap.nr = force_nr;
+ ret = i2c_add_numbered_adapter(&priv->adap);
+ } else {
+ ret = i2c_add_adapter(&priv->adap);
+ }
+ if (ret < 0) {
+ dev_err(&parent->dev, "failed to add mux-adapter (error=%d)\n",
+ ret);
+ kfree(priv);
+ return NULL;
+ }
+
+ list_add_tail(&priv->adap.mux_list, &parent->mux_list_head);
+
+ dev_info(&parent->dev, "i2c-mux-%d: Multiplexed I2C bus on "
+ "parent bus i2c-%d, chan_id %d\n",
+ i2c_adapter_id(&priv->adap), i2c_adapter_id(parent), chan_id);
+
+ return &priv->adap;
+}
+EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
+
+int i2c_del_mux_adapter(struct i2c_adapter *adap)
+{
+ struct i2c_mux_priv *priv = adap->algo_data;
+ int ret;
+ struct i2c_adapter *child, *next, *parent;
+
+ if (adap->dev.parent != NULL
+ && adap->dev.parent->bus == &i2c_bus_type) {
+ parent = to_i2c_adapter(adap->dev.parent);
+ list_for_each_entry_safe(child, next, &parent->mux_list_head,
+ mux_list) {
+ if (child == adap) {
+ list_del(&child->mux_list);
+ break;
+ }
+ }
+ }
+
+ ret = i2c_del_adapter(adap);
+ if (ret < 0)
+ return ret;
+ kfree(priv);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>");
+MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
new file mode 100755
index 0000000..0d5d6c8
--- /dev/null
+++ b/include/linux/i2c-mux.h
@@ -0,0 +1,46 @@
+/*
+ *
+ * i2c-mux.h - functions for the i2c-bus mux support
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
+ * Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _LINUX_I2C_MUX_H
+#define _LINUX_I2C_MUX_H
+
+#ifdef __KERNEL__
+
+/*
+ * Called to create a i2c bus on a multiplexed bus segment.
+ * The mux_dev and chan_id parameters are passed to the select
+ * and deselect callback functions to perform hardware-specific
+ * mux control.
+ */
+struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
+ void *mux_dev, u32 force_nr, u32 chan_id,
+ int (*select) (struct i2c_adapter *adap,
+ void *mux_dev, u32 chan_id),
+ int (*deselect) (struct i2c_adapter *,
+ void *mux_dev, u32 chan_id));
+
+int i2c_del_mux_adapter(struct i2c_adapter *adap);
+
+#endif /* __KERNEL__ */
+
+#endif /* _LINUX_I2C_H */
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 1fd7b12..898a8c1 100755
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -349,6 +349,8 @@ struct i2c_adapter {
struct completion dev_released;
struct list_head userspace_clients;
+ struct list_head mux_list_head;
+ struct list_head mux_list;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
@@ -380,6 +382,15 @@ static inline void i2c_unlock_adapter(struct i2c_adapter *adapter)
rt_mutex_unlock(&adapter->bus_lock);
}
+/**
+ * i2c_trylock_adapter - Try to prevent access to an I2C bus segment
+ * @adapter: Target I2C bus segment
+ */
+static inline int i2c_trylock_adapter(struct i2c_adapter *adapter)
+{
+ return rt_mutex_trylock(&adapter->bus_lock);
+}
+
/*flags for the client struct: */
#define I2C_CLIENT_PEC 0x04 /* Use Packet Error Checking */
#define I2C_CLIENT_TEN 0x10 /* we have a ten bit chip address */
--
1.6.2.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x
[not found] ` <4BE01741.1010909-Mmb7MZpHnFY@public.gmane.org>
@ 2010-05-04 12:48 ` Michael Lawnick
[not found] ` <4BE01795.1090605-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:52 ` [PATCH v2 1/2] i2c: Multiplexed I2C bus core support Rodolfo Giometti
` (2 subsequent siblings)
3 siblings, 1 reply; 20+ messages in thread
From: Michael Lawnick @ 2010-05-04 12:48 UTC (permalink / raw)
To: Linux I2C; +Cc: Delvare, Jean , Rodolfo Giometti
[-- Attachment #1: Type: text/plain, Size: 0 bytes --]
[-- Attachment #2: 0002-pca954x-mux.patch --]
[-- Type: text/plain, Size: 12150 bytes --]
Add multiplexed bus core support. I2C driver for PCA954x
I2C multiplexer series.
Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
---
Based on kernel 2.6.33 +
[PATCH] i2c-core: Use per-adapter userspace device lists
by Jean Delware <20100424201914.08b3f008-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
<http://article.gmane.org/gmane.linux.drivers.i2c/5994/>
drivers/i2c/Kconfig | 2 +
drivers/i2c/Makefile | 2 +-
drivers/i2c/muxes/Kconfig | 17 +++
drivers/i2c/muxes/Makefile | 8 +
drivers/i2c/muxes/pca954x.c | 302 +++++++++++++++++++++++++++++++++++++++++++
include/linux/i2c/pca954x.h | 47 +++++++
6 files changed, 377 insertions(+), 1 deletions(-)
create mode 100755 drivers/i2c/muxes/Kconfig
create mode 100755 drivers/i2c/muxes/Makefile
create mode 100755 drivers/i2c/muxes/pca954x.c
create mode 100755 include/linux/i2c/pca954x.h
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 2cd6d78..21b0ac0 100755
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -44,6 +44,8 @@ config I2C_MUX
handle multiplexed I2C bus topologies, by presenting each
multiplexed segment as a I2C adapter.
+source drivers/i2c/muxes/Kconfig
+
config I2C_CHARDEV
tristate "I2C device interface"
help
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index a488e8b..1769a16 100755
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -6,7 +6,7 @@ obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
obj-$(CONFIG_I2C) += i2c-core.o
obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
obj-$(CONFIG_I2C_MUX) += i2c-mux.o
-obj-y += busses/ chips/ algos/
+obj-y += busses/ chips/ muxes/ algos/
ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
EXTRA_CFLAGS += -DDEBUG
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
new file mode 100755
index 0000000..ec22db0
--- /dev/null
+++ b/drivers/i2c/muxes/Kconfig
@@ -0,0 +1,17 @@
+#
+# Multiplexer I2C chip drivers configuration
+#
+
+menu "Multiplexer I2C Chip support"
+ depends on I2C_MUX && EXPERIMENTAL
+
+config I2C_MUX_PCA954x
+ tristate "Philips PCA954x I2C Mux/switches"
+ help
+ If you say yes here you get support for the Philips PCA954x
+ I2C mux/switch devices.
+
+ This driver can also be built as a module. If so, the module
+ will be called pca954x.
+
+endmenu
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
new file mode 100755
index 0000000..575c1ca
--- /dev/null
+++ b/drivers/i2c/muxes/Makefile
@@ -0,0 +1,8 @@
+#
+# Makefile for multiplexer I2C chip drivers.
+
+obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o
+
+ifeq ($(I2C_DEBUG_BUS),y)
+EXTRA_CFLAGS += -DDEBUG
+endif
diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
new file mode 100755
index 0000000..12b5eb7
--- /dev/null
+++ b/drivers/i2c/muxes/pca954x.c
@@ -0,0 +1,302 @@
+/*
+ * I2C multiplexer
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
+ *
+ * This module supports the PCA954x series of I2C multiplexer/switch chips
+ * made by Philips Semiconductors.
+ * This includes the:
+ * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
+ * and PCA9548.
+ *
+ * These chips are all controlled via the I2C bus itself, and all have a
+ * single 8-bit register. The upstream "parent" bus fans out to two,
+ * four, or eight downstream busses or channels; which of these
+ * are selected is determined by the chip type and register contents. A
+ * mux can select only one sub-bus at a time; a switch can select any
+ * combination simultaneously.
+ *
+ * Based on:
+ * pca954x.c from Kumar Gala <galak-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
+ * Copyright (C) 2006
+ *
+ * Based on:
+ * pca954x.c from Ken Harrenstien
+ * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
+ *
+ * Based on:
+ * i2c-virtual_cb.c from Brian Kuschak <bkuschak-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>
+ * and
+ * pca9540.c from Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>.
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+
+#include <linux/i2c/pca954x.h>
+
+#define PCA954X_MAX_NCHANS 8
+
+enum pca_type {
+ pca_9540,
+ pca_9542,
+ pca_9543,
+ pca_9544,
+ pca_9545,
+ pca_9546,
+ pca_9547,
+ pca_9548,
+};
+
+struct pca954x {
+ enum pca_type type;
+ struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
+
+ u8 last_chan;
+};
+
+struct chip_desc {
+ u8 nchans;
+ u8 enable; /* used for muxes only */
+ enum muxtype {
+ pca954x_ismux = 0,
+ pca954x_isswi
+ } muxtype;
+};
+
+/* Provide specs for the PCA954x types we know about */
+static const struct chip_desc chips[] = {
+ [pca_9540] = {
+ .nchans = 2,
+ .enable = 0x4,
+ .muxtype = pca954x_ismux,
+ },
+ [pca_9543] = {
+ .nchans = 2,
+ .muxtype = pca954x_isswi,
+ },
+ [pca_9544] = {
+ .nchans = 4,
+ .enable = 0x4,
+ .muxtype = pca954x_ismux,
+ },
+ [pca_9545] = {
+ .nchans = 4,
+ .muxtype = pca954x_isswi,
+ },
+ [pca_9547] = {
+ .nchans = 8,
+ .enable = 0x8,
+ .muxtype = pca954x_ismux,
+ },
+ [pca_9548] = {
+ .nchans = 8,
+ .muxtype = pca954x_isswi,
+ },
+};
+
+static const struct i2c_device_id pca954x_id[] = {
+ { "pca9540", pca_9540 },
+ { "pca9542", pca_9540 },
+ { "pca9543", pca_9543 },
+ { "pca9544", pca_9544 },
+ { "pca9545", pca_9545 },
+ { "pca9546", pca_9545 },
+ { "pca9547", pca_9547 },
+ { "pca9548", pca_9548 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, pca954x_id);
+
+/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ for this as they will try to lock adapter a second time */
+static int pca954x_reg_write(struct i2c_adapter *adap,
+ struct i2c_client *client, u8 val)
+{
+ int ret = -ENODEV;
+
+ if (adap->algo->master_xfer) {
+ struct i2c_msg msg;
+ char buf[1];
+
+ msg.addr = client->addr;
+ msg.flags = I2C_SMBUS_WRITE;
+ msg.len = 1;
+ buf[0] = val;
+ msg.buf = buf;
+ ret = adap->algo->master_xfer(adap, &msg, 1);
+ } else {
+ union i2c_smbus_data data;
+ ret = adap->algo->smbus_xfer(adap, client->addr,
+ client->flags,
+ I2C_SMBUS_WRITE,
+ val, I2C_SMBUS_BYTE, &data);
+ }
+
+ return ret;
+}
+
+static int pca954x_select_chan(struct i2c_adapter *adap,
+ void *client, u32 chan)
+{
+ struct pca954x *data = i2c_get_clientdata(client);
+ const struct chip_desc *chip = &chips[data->type];
+ u8 regval;
+ int ret = 0;
+
+ /* we make switches look like muxes, not sure how to be smarter */
+ if (chip->muxtype == pca954x_ismux)
+ regval = chan | chip->enable;
+ else
+ regval = 1 << chan;
+
+ /* Only select the channel if its different from the last channel */
+ if (data->last_chan != chan) {
+ ret = pca954x_reg_write(adap, client, regval);
+ data->last_chan = chan;
+ }
+
+ return ret;
+}
+
+static int pca954x_deselect_mux(struct i2c_adapter *adap,
+ void *client, u32 chan)
+{
+ struct pca954x *data = i2c_get_clientdata(client);
+
+ /* Deselect active channel */
+ data->last_chan = 0;
+ return pca954x_reg_write(adap, client, data->last_chan);
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int __devinit pca954x_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+ struct pca954x_platform_data *pdata = client->dev.platform_data;
+ int num, force;
+ struct pca954x *data;
+ int ret = -ENODEV;
+
+ if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
+ goto err;
+
+ data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
+ if (!data) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ i2c_set_clientdata(client, data);
+
+ /* Read the mux register at addr to verify
+ * that the mux is in fact present.
+ */
+ if (i2c_smbus_read_byte(client) < 0) {
+ dev_warn(&client->dev, "probe failed\n");
+ goto exit_free;
+ }
+
+ data->type = id->driver_data;
+ data->last_chan = 0; /* force the first selection */
+
+ /* Now create an adapter for each channel */
+ for (num = 0; num < chips[data->type].nchans; num++) {
+ force = 0; /* dynamic adap number */
+ if (pdata) {
+ if (num < pdata->num_modes)
+ /* force static number */
+ force = pdata->modes[num].adap_id;
+ else
+ /* discard unconfigured channels */
+ break;
+ }
+
+ data->virt_adaps[num] =
+ i2c_add_mux_adapter(adap, client,
+ force, num, &pca954x_select_chan,
+ (pdata && pdata->modes[num].deselect_on_exit)
+ ? &pca954x_deselect_mux : NULL);
+
+ if (data->virt_adaps[num] == NULL) {
+ ret = -ENODEV;
+ printk(KERN_ERR
+ "%s %s: failed to register multiplexed adapter"
+ " %d at bus %d\n", __FILE__, __func__, num,
+ force);
+ goto virt_reg_failed;
+ }
+ }
+
+ dev_info(&client->dev,
+ "registered %d multiplexed busses for I2C %s %s\n",
+ num, chips[data->type].muxtype == pca954x_ismux
+ ? "mux" : "switch", client->name);
+
+ return 0;
+
+virt_reg_failed:
+ for (num--; num >= 0; num--)
+ i2c_del_mux_adapter(data->virt_adaps[num]);
+exit_free:
+ kfree(data);
+err:
+ return ret;
+}
+
+static int __devexit pca954x_remove(struct i2c_client *client)
+{
+ struct pca954x *data = i2c_get_clientdata(client);
+ const struct chip_desc *chip = &chips[data->type];
+ int i, err;
+
+ for (i = 0; i < chip->nchans; ++i)
+ if (data->virt_adaps[i]) {
+ err = i2c_del_mux_adapter(data->virt_adaps[i]);
+ if (err)
+ return err;
+ data->virt_adaps[i] = NULL;
+ }
+
+ kfree(data);
+ return 0;
+}
+
+static struct i2c_driver pca954x_driver = {
+ .driver = {
+ .name = "pca954x",
+ .owner = THIS_MODULE,
+ },
+ .probe = pca954x_probe,
+ .remove = __devexit_p(pca954x_remove),
+ .id_table = pca954x_id,
+};
+
+static int __init pca954x_init(void)
+{
+ return i2c_add_driver(&pca954x_driver);
+}
+
+static void __exit pca954x_exit(void)
+{
+ i2c_del_driver(&pca954x_driver);
+}
+
+module_init(pca954x_init);
+module_exit(pca954x_exit);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>");
+MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/i2c/pca954x.h b/include/linux/i2c/pca954x.h
new file mode 100755
index 0000000..8032269
--- /dev/null
+++ b/include/linux/i2c/pca954x.h
@@ -0,0 +1,47 @@
+/*
+ *
+ * pca954x.h - I2C multiplexer/switch support
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
+ * Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+#ifndef _I2C_PCA954X_H
+#define _I2C_PCA954X_H
+
+/* Platform data for the PCA954x I2C multiplexers */
+
+/* Per channel initialisation data:
+ * @adap_id: bus number for the adapter. 0 = don't care
+ * @deselect_on_exit: set this entry to 1, if your H/W needs deselection
+ * of this channel after transaction.
+ *
+ */
+struct pca954x_platform_mode {
+ int adap_id;
+ unsigned int deselect_on_exit:1;
+};
+
+/* Per mux/switch data, used with i2c_register_board_info */
+struct pca954x_platform_data {
+ struct pca954x_platform_mode *modes;
+ int num_modes;
+};
+
+#endif /*_I2C_PCA954X_H*/
--
1.6.2.1
^ permalink raw reply related [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4BE01741.1010909-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:48 ` [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x Michael Lawnick
@ 2010-05-04 12:52 ` Rodolfo Giometti
2010-05-17 7:36 ` Michael Lawnick
2010-06-10 13:24 ` Jean Delvare
3 siblings, 0 replies; 20+ messages in thread
From: Rodolfo Giometti @ 2010-05-04 12:52 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Delvare, Jean
On Tue, May 04, 2010 at 02:46:57PM +0200, Michael Lawnick wrote:
> Add multiplexed bus core support. I2C multiplexer and switches
> like pca954x get instantiated as new adapters per output.
>
> Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
Acked-by: Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
--
GNU/Linux Solutions e-mail: giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org
Linux Device Driver giometti-k2GhghHVRtY@public.gmane.org
Embedded Systems phone: +39 349 2432127
UNIX programming skype: rodolfo.giometti
Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x
[not found] ` <4BE01795.1090605-Mmb7MZpHnFY@public.gmane.org>
@ 2010-05-04 12:52 ` Rodolfo Giometti
2010-06-09 16:41 ` Jean Delvare
2010-06-13 12:11 ` Jean Delvare
2 siblings, 0 replies; 20+ messages in thread
From: Rodolfo Giometti @ 2010-05-04 12:52 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Delvare, Jean
On Tue, May 04, 2010 at 02:48:21PM +0200, Michael Lawnick wrote:
> Add multiplexed bus core support. I2C driver for PCA954x
> I2C multiplexer series.
>
> Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
Acked-by: Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
--
GNU/Linux Solutions e-mail: giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org
Linux Device Driver giometti-k2GhghHVRtY@public.gmane.org
Embedded Systems phone: +39 349 2432127
UNIX programming skype: rodolfo.giometti
Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4BE01741.1010909-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:48 ` [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x Michael Lawnick
2010-05-04 12:52 ` [PATCH v2 1/2] i2c: Multiplexed I2C bus core support Rodolfo Giometti
@ 2010-05-17 7:36 ` Michael Lawnick
[not found] ` <4BF0F200.5090604-Mmb7MZpHnFY@public.gmane.org>
2010-06-10 13:24 ` Jean Delvare
3 siblings, 1 reply; 20+ messages in thread
From: Michael Lawnick @ 2010-05-17 7:36 UTC (permalink / raw)
To: Linux I2C; +Cc: Delvare, Jean
Michael Lawnick said the following:
> Add multiplexed bus core support.
...
Ping
Jean, still any chance to get that done into .35?
--
KR
Michael Lawnick
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4BF0F200.5090604-Mmb7MZpHnFY@public.gmane.org>
@ 2010-05-17 8:15 ` Jean Delvare
0 siblings, 0 replies; 20+ messages in thread
From: Jean Delvare @ 2010-05-17 8:15 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C
Hi Michael,
On Mon, 17 May 2010 09:36:32 +0200, Michael Lawnick wrote:
> Michael Lawnick said the following:
> > Add multiplexed bus core support.
> ...
>
> Ping
>
> Jean, still any chance to get that done into .35?
I hope so, yes. I am busy with the w83795 driver right now, hope to get
some time to review your updated patches this week. Stay tuned.
--
Jean Delvare
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x
[not found] ` <4BE01795.1090605-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:52 ` Rodolfo Giometti
@ 2010-06-09 16:41 ` Jean Delvare
[not found] ` <20100609184143.06488f2f-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2010-06-13 12:11 ` Jean Delvare
2 siblings, 1 reply; 20+ messages in thread
From: Jean Delvare @ 2010-06-09 16:41 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Rodolfo Giometti
Hi Michael,
On Tue, 04 May 2010 14:48:21 +0200, Michael Lawnick wrote:
> Add multiplexed bus core support. I2C driver for PCA954x
> I2C multiplexer series.
>
> Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
Review:
>
> ---
> Based on kernel 2.6.33 +
> [PATCH] i2c-core: Use per-adapter userspace device lists
> by Jean Delware <20100424201914.08b3f008-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
> <http://article.gmane.org/gmane.linux.drivers.i2c/5994/>
>
> drivers/i2c/Kconfig | 2 +
> drivers/i2c/Makefile | 2 +-
> drivers/i2c/muxes/Kconfig | 17 +++
> drivers/i2c/muxes/Makefile | 8 +
> drivers/i2c/muxes/pca954x.c | 302 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/i2c/pca954x.h | 47 +++++++
> 6 files changed, 377 insertions(+), 1 deletions(-)
> create mode 100755 drivers/i2c/muxes/Kconfig
> create mode 100755 drivers/i2c/muxes/Makefile
> create mode 100755 drivers/i2c/muxes/pca954x.c
> create mode 100755 include/linux/i2c/pca954x.h
I don't really care, as I use quilt for my patches, but the above modes
are wrong: should be 100644.
>
> diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
> index 2cd6d78..21b0ac0 100755
> --- a/drivers/i2c/Kconfig
> +++ b/drivers/i2c/Kconfig
> @@ -44,6 +44,8 @@ config I2C_MUX
> handle multiplexed I2C bus topologies, by presenting each
> multiplexed segment as a I2C adapter.
>
> +source drivers/i2c/muxes/Kconfig
> +
> config I2C_CHARDEV
> tristate "I2C device interface"
> help
> diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
> index a488e8b..1769a16 100755
> --- a/drivers/i2c/Makefile
> +++ b/drivers/i2c/Makefile
> @@ -6,7 +6,7 @@ obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
> obj-$(CONFIG_I2C) += i2c-core.o
> obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
> obj-$(CONFIG_I2C_MUX) += i2c-mux.o
> -obj-y += busses/ chips/ algos/
> +obj-y += busses/ chips/ muxes/ algos/
>
> ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
> EXTRA_CFLAGS += -DDEBUG
> diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
> new file mode 100755
> index 0000000..ec22db0
> --- /dev/null
> +++ b/drivers/i2c/muxes/Kconfig
> @@ -0,0 +1,17 @@
> +#
> +# Multiplexer I2C chip drivers configuration
> +#
> +
> +menu "Multiplexer I2C Chip support"
> + depends on I2C_MUX && EXPERIMENTAL
The dependency on EXPERIMENTAL is odd for a menu. I'd rather move it
down to individual drivers, so that we can them remove them later on a
case-by-case basis.
> +
> +config I2C_MUX_PCA954x
> + tristate "Philips PCA954x I2C Mux/switches"
> + help
> + If you say yes here you get support for the Philips PCA954x
> + I2C mux/switch devices.
> +
> + This driver can also be built as a module. If so, the module
> + will be called pca954x.
> +
> +endmenu
> diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
> new file mode 100755
> index 0000000..575c1ca
> --- /dev/null
> +++ b/drivers/i2c/muxes/Makefile
> @@ -0,0 +1,8 @@
> +#
> +# Makefile for multiplexer I2C chip drivers.
> +
> +obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o
> +
> +ifeq ($(I2C_DEBUG_BUS),y)
I think you mean CONFIG_I2C_DEBUG_BUS here.
> +EXTRA_CFLAGS += -DDEBUG
> +endif
> diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
> new file mode 100755
> index 0000000..12b5eb7
> --- /dev/null
> +++ b/drivers/i2c/muxes/pca954x.c
> @@ -0,0 +1,302 @@
> +/*
> + * I2C multiplexer
> + *
> + * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
> + * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
> + *
> + * This module supports the PCA954x series of I2C multiplexer/switch chips
> + * made by Philips Semiconductors.
> + * This includes the:
> + * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
> + * and PCA9548.
> + *
> + * These chips are all controlled via the I2C bus itself, and all have a
> + * single 8-bit register. The upstream "parent" bus fans out to two,
> + * four, or eight downstream busses or channels; which of these
> + * are selected is determined by the chip type and register contents. A
> + * mux can select only one sub-bus at a time; a switch can select any
> + * combination simultaneously.
> + *
> + * Based on:
> + * pca954x.c from Kumar Gala <galak-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
> + * Copyright (C) 2006
> + *
> + * Based on:
> + * pca954x.c from Ken Harrenstien
> + * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
> + *
> + * Based on:
> + * i2c-virtual_cb.c from Brian Kuschak <bkuschak-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>
> + * and
> + * pca9540.c from Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>.
> + *
> + * 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/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/device.h>
> +#include <linux/i2c.h>
> +#include <linux/i2c-mux.h>
> +
> +#include <linux/i2c/pca954x.h>
> +
> +#define PCA954X_MAX_NCHANS 8
> +
> +enum pca_type {
> + pca_9540,
> + pca_9542,
> + pca_9543,
> + pca_9544,
> + pca_9545,
> + pca_9546,
> + pca_9547,
> + pca_9548,
> +};
> +
> +struct pca954x {
> + enum pca_type type;
> + struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
> +
> + u8 last_chan;
This indentation doesn't make much sense.
> +};
> +
> +struct chip_desc {
> + u8 nchans;
> + u8 enable; /* used for muxes only */
> + enum muxtype {
> + pca954x_ismux = 0,
> + pca954x_isswi
> + } muxtype;
> +};
> +
> +/* Provide specs for the PCA954x types we know about */
> +static const struct chip_desc chips[] = {
> + [pca_9540] = {
> + .nchans = 2,
> + .enable = 0x4,
> + .muxtype = pca954x_ismux,
> + },
> + [pca_9543] = {
> + .nchans = 2,
> + .muxtype = pca954x_isswi,
> + },
> + [pca_9544] = {
> + .nchans = 4,
> + .enable = 0x4,
> + .muxtype = pca954x_ismux,
> + },
> + [pca_9545] = {
> + .nchans = 4,
> + .muxtype = pca954x_isswi,
> + },
> + [pca_9547] = {
> + .nchans = 8,
> + .enable = 0x8,
> + .muxtype = pca954x_ismux,
> + },
> + [pca_9548] = {
> + .nchans = 8,
> + .muxtype = pca954x_isswi,
> + },
> +};
> +
> +static const struct i2c_device_id pca954x_id[] = {
> + { "pca9540", pca_9540 },
> + { "pca9542", pca_9540 },
> + { "pca9543", pca_9543 },
> + { "pca9544", pca_9544 },
> + { "pca9545", pca_9545 },
> + { "pca9546", pca_9545 },
> + { "pca9547", pca_9547 },
> + { "pca9548", pca_9548 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, pca954x_id);
> +
> +/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
> + for this as they will try to lock adapter a second time */
> +static int pca954x_reg_write(struct i2c_adapter *adap,
> + struct i2c_client *client, u8 val)
> +{
> + int ret = -ENODEV;
Useless initialization.
> +
> + if (adap->algo->master_xfer) {
> + struct i2c_msg msg;
> + char buf[1];
> +
> + msg.addr = client->addr;
> + msg.flags = I2C_SMBUS_WRITE;
That's not correct. You want to use 0 here (as writes are the default,
in the absence of I2C_M_RD).
> + msg.len = 1;
> + buf[0] = val;
> + msg.buf = buf;
> + ret = adap->algo->master_xfer(adap, &msg, 1);
> + } else {
> + union i2c_smbus_data data;
> + ret = adap->algo->smbus_xfer(adap, client->addr,
> + client->flags,
> + I2C_SMBUS_WRITE,
> + val, I2C_SMBUS_BYTE, &data);
> + }
> +
> + return ret;
> +}
> +
> +static int pca954x_select_chan(struct i2c_adapter *adap,
> + void *client, u32 chan)
> +{
> + struct pca954x *data = i2c_get_clientdata(client);
> + const struct chip_desc *chip = &chips[data->type];
> + u8 regval;
> + int ret = 0;
> +
> + /* we make switches look like muxes, not sure how to be smarter */
> + if (chip->muxtype == pca954x_ismux)
> + regval = chan | chip->enable;
> + else
> + regval = 1 << chan;
> +
> + /* Only select the channel if its different from the last channel */
> + if (data->last_chan != chan) {
> + ret = pca954x_reg_write(adap, client, regval);
> + data->last_chan = chan;
> + }
> +
> + return ret;
> +}
> +
> +static int pca954x_deselect_mux(struct i2c_adapter *adap,
> + void *client, u32 chan)
> +{
> + struct pca954x *data = i2c_get_clientdata(client);
> +
> + /* Deselect active channel */
> + data->last_chan = 0;
> + return pca954x_reg_write(adap, client, data->last_chan);
> +}
> +
> +/*
> + * I2C init/probing/exit functions
> + */
> +static int __devinit pca954x_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
> + struct pca954x_platform_data *pdata = client->dev.platform_data;
> + int num, force;
> + struct pca954x *data;
> + int ret = -ENODEV;
> +
> + if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
> + goto err;
> +
> + data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
> + if (!data) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + i2c_set_clientdata(client, data);
> +
> + /* Read the mux register at addr to verify
> + * that the mux is in fact present.
> + */
> + if (i2c_smbus_read_byte(client) < 0) {
> + dev_warn(&client->dev, "probe failed\n");
> + goto exit_free;
> + }
> +
> + data->type = id->driver_data;
> + data->last_chan = 0; /* force the first selection */
> +
> + /* Now create an adapter for each channel */
> + for (num = 0; num < chips[data->type].nchans; num++) {
> + force = 0; /* dynamic adap number */
> + if (pdata) {
> + if (num < pdata->num_modes)
> + /* force static number */
> + force = pdata->modes[num].adap_id;
> + else
> + /* discard unconfigured channels */
> + break;
> + }
> +
> + data->virt_adaps[num] =
> + i2c_add_mux_adapter(adap, client,
> + force, num, &pca954x_select_chan,
> + (pdata && pdata->modes[num].deselect_on_exit)
> + ? &pca954x_deselect_mux : NULL);
Functions are already addresses, the leading & isn't needed.
> +
> + if (data->virt_adaps[num] == NULL) {
> + ret = -ENODEV;
> + printk(KERN_ERR
Please use dev_err().
> + "%s %s: failed to register multiplexed adapter"
> + " %d at bus %d\n", __FILE__, __func__, num,
I think you mean "as bus", not "at bus".
> + force);
> + goto virt_reg_failed;
> + }
> + }
> +
> + dev_info(&client->dev,
> + "registered %d multiplexed busses for I2C %s %s\n",
> + num, chips[data->type].muxtype == pca954x_ismux
> + ? "mux" : "switch", client->name);
> +
> + return 0;
> +
> +virt_reg_failed:
> + for (num--; num >= 0; num--)
> + i2c_del_mux_adapter(data->virt_adaps[num]);
> +exit_free:
> + kfree(data);
> +err:
> + return ret;
> +}
> +
> +static int __devexit pca954x_remove(struct i2c_client *client)
> +{
> + struct pca954x *data = i2c_get_clientdata(client);
> + const struct chip_desc *chip = &chips[data->type];
> + int i, err;
> +
> + for (i = 0; i < chip->nchans; ++i)
> + if (data->virt_adaps[i]) {
> + err = i2c_del_mux_adapter(data->virt_adaps[i]);
> + if (err)
> + return err;
> + data->virt_adaps[i] = NULL;
> + }
> +
> + kfree(data);
> + return 0;
> +}
> +
> +static struct i2c_driver pca954x_driver = {
> + .driver = {
> + .name = "pca954x",
> + .owner = THIS_MODULE,
> + },
> + .probe = pca954x_probe,
> + .remove = __devexit_p(pca954x_remove),
> + .id_table = pca954x_id,
> +};
> +
> +static int __init pca954x_init(void)
> +{
> + return i2c_add_driver(&pca954x_driver);
> +}
> +
> +static void __exit pca954x_exit(void)
> +{
> + i2c_del_driver(&pca954x_driver);
> +}
> +
> +module_init(pca954x_init);
> +module_exit(pca954x_exit);
> +
> +MODULE_AUTHOR("Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>");
> +MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/i2c/pca954x.h b/include/linux/i2c/pca954x.h
> new file mode 100755
> index 0000000..8032269
> --- /dev/null
> +++ b/include/linux/i2c/pca954x.h
> @@ -0,0 +1,47 @@
> +/*
> + *
> + * pca954x.h - I2C multiplexer/switch support
> + *
> + * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
> + * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
> + * Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +
> +#ifndef _I2C_PCA954X_H
Should be prefixed with _LINUX to avoid any confusion.
> +#define _I2C_PCA954X_H
> +
> +/* Platform data for the PCA954x I2C multiplexers */
> +
> +/* Per channel initialisation data:
> + * @adap_id: bus number for the adapter. 0 = don't care
> + * @deselect_on_exit: set this entry to 1, if your H/W needs deselection
> + * of this channel after transaction.
> + *
> + */
> +struct pca954x_platform_mode {
> + int adap_id;
> + unsigned int deselect_on_exit:1;
> +};
> +
> +/* Per mux/switch data, used with i2c_register_board_info */
> +struct pca954x_platform_data {
> + struct pca954x_platform_mode *modes;
> + int num_modes;
Please use tabs for indentation.
> +};
> +
> +#endif /*_I2C_PCA954X_H*/
Missing spaces.
I've fixed all these small issues myself; no need to resend. Thanks (to
you and Rodolfo as well) for your contribution!
--
Jean Delvare
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x
[not found] ` <20100609184143.06488f2f-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
@ 2010-06-10 10:15 ` Michael Lawnick
0 siblings, 0 replies; 20+ messages in thread
From: Michael Lawnick @ 2010-06-10 10:15 UTC (permalink / raw)
To: Jean Delvare; +Cc: Linux I2C, Rodolfo Giometti
Jean Delvare said the following:
> Hi Michael,
>
> On Tue, 04 May 2010 14:48:21 +0200, Michael Lawnick wrote:
>> Add multiplexed bus core support. I2C driver for PCA954x
>> I2C multiplexer series.
>>
>> Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
>
>
> Review:
...
> I've fixed all these small issues myself; no need to resend. Thanks (to
> you and Rodolfo as well) for your contribution!
>
Thank You!
--
KR
Michael
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4BE01741.1010909-Mmb7MZpHnFY@public.gmane.org>
` (2 preceding siblings ...)
2010-05-17 7:36 ` Michael Lawnick
@ 2010-06-10 13:24 ` Jean Delvare
[not found] ` <20100610152411.5497461c-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
3 siblings, 1 reply; 20+ messages in thread
From: Jean Delvare @ 2010-06-10 13:24 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Rodolfo Giometti
Hi Michael,
On Tue, 04 May 2010 14:46:57 +0200, Michael Lawnick wrote:
> Add multiplexed bus core support. I2C multiplexer and switches
> like pca954x get instantiated as new adapters per output.
>
> Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
>
> ---
> Based on kernel 2.6.33 +
> [PATCH] i2c-core: Use per-adapter userspace device lists
> by Jean Delware <20100424201914.08b3f008-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
> <http://article.gmane.org/gmane.linux.drivers.i2c/5994/>
Future patches should be based on 2.6.34 at least... 2.6.35-rc2 would
be even better.
Review follows. Need some more work I fear, but not that much... Please
let me know if you are going to submit another iteration, or if you
prefer to let me fix things the way I like (in which case I'll still
ask you to test my version of the patch when I'm done.)
>
> drivers/i2c/Kconfig | 8 ++
> drivers/i2c/Makefile | 1 +
> drivers/i2c/i2c-core.c | 93 ++++++++++++++++++++++--
> drivers/i2c/i2c-dev.c | 46 ++++++++++++-
> drivers/i2c/i2c-mux.c | 184 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/i2c-mux.h | 46 ++++++++++++
> include/linux/i2c.h | 11 +++
> 7 files changed, 381 insertions(+), 8 deletions(-)
> create mode 100755 drivers/i2c/i2c-mux.c
> create mode 100755 include/linux/i2c-mux.h
>
> diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
> index 8d8a00e..2cd6d78 100755
> --- a/drivers/i2c/Kconfig
> +++ b/drivers/i2c/Kconfig
> @@ -36,6 +36,14 @@ config I2C_COMPAT
> other user-space package which expects i2c adapters to be class
> devices. If you don't know, say Y.
>
> +config I2C_MUX
> + tristate "I2C bus multiplexing support"
> + depends on I2C
Dependency on I2C isn't needed: this configuration item is already
in an "if I2C" block. A dependency on EXPERIMENTAL might be a good idea
for the time being though.
> + help
> + Say Y here if you want the I2C core to support the ability to
> + handle multiplexed I2C bus topologies, by presenting each
> + multiplexed segment as a I2C adapter.
For support that can be build as a module, we usually add a sentence
saying so and giving the name of the module.
> +
I would move config I2C_MUX below config I2C_CHARDEV, to make it
consistent with Makefile, and also because users expect new options to
be added after existing options.
> config I2C_CHARDEV
> tristate "I2C device interface"
> help
> diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
> index ba26e6c..a488e8b 100755
> --- a/drivers/i2c/Makefile
> +++ b/drivers/i2c/Makefile
> @@ -5,6 +5,7 @@
> obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
> obj-$(CONFIG_I2C) += i2c-core.o
> obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
> +obj-$(CONFIG_I2C_MUX) += i2c-mux.o
> obj-y += busses/ chips/ algos/
>
> ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> index fc93e28..682966a 100755
> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -20,7 +20,10 @@
> /* With some changes from Kyösti Mälkki <kmalkki-kf+aQKke1yb1KXRcyAk9cg@public.gmane.org>.
> All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
> SMBus 2.0 support by Mark Studebaker <mdsxyz123-/E1597aS9LQAvxtiuMwx3w@public.gmane.org> and
> - Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org> */
> + Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
> + Mux support by Rodolfo Giometti <giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org> and
> + Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org> */
> +
Extra blank line.
>
> #include <linux/module.h>
> #include <linux/kernel.h>
> @@ -288,6 +291,12 @@ struct i2c_client *i2c_verify_client(struct device *dev)
> }
> EXPORT_SYMBOL(i2c_verify_client);
>
> +static int i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
> +{
> + return adapter->dev.parent != NULL
> + && adapter->dev.parent->bus == &i2c_bus_type;
> +}
> +
>
> /**
> * i2c_new_device - instantiate an i2c device
> @@ -624,6 +633,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
>
> rt_mutex_init(&adap->bus_lock);
> INIT_LIST_HEAD(&adap->userspace_clients);
> + INIT_LIST_HEAD(&adap->mux_list_head);
>
> /* Set default timeout to 1 second if not already set */
> if (adap->timeout == 0)
> @@ -949,9 +959,78 @@ static int __i2c_check_addr(struct device *dev, void *addrp)
> return 0;
> }
>
> +/* walk up mux tree */
> +static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
> +{
> + int result;
> +
> + result = device_for_each_child(&adapter->dev, &addr, __i2c_check_addr);
> +
> + if (!result && i2c_parent_is_i2c_adapter(adapter))
> + result = i2c_check_mux_parents(
> + to_i2c_adapter(adapter->dev.parent), addr);
> +
> + return result;
> +}
> +
> +/* recurse down mux tree */
> +static int i2c_check_mux_childs(struct i2c_adapter *adapter, int addr)
"childs" doesn't exist in proper English, the right work is "children" ;)
> +{
> + int result = 0;
> + struct i2c_adapter *child, *next;
> +
> + list_for_each_entry_safe(child, next, &adapter->mux_list_head,
> + mux_list) {
> + result = device_for_each_child(&child->dev, &addr,
> + __i2c_check_addr);
> + if (result)
> + break;
> + result = i2c_check_mux_childs(child, addr);
This value is ignored, except for the last child. I think you should
break here too.
> + }
> + return result;
> +}
> +
> static int i2c_check_addr(struct i2c_adapter *adapter, int addr)
> {
> - return device_for_each_child(&adapter->dev, &addr, __i2c_check_addr);
> + int result;
> +
> + result = i2c_check_mux_parents(adapter, addr);
> +
> + if (!result)
> + result = i2c_check_mux_childs(adapter, addr);
> +
> + return result;
> +}
I am worried about (the lack of) locking when the above function is
called. The problem isn't new with your patch, but your patch makes it
worse: beforehand, the driver core would complain if we hit a race
here, because we would try to create two clients with the same bus_id as
a result. But now, we may create 2 conflicting clients with different
bus_id, so the driver core will not complain.
I'll think about it some more, and add locking if needed.
> +static void i2c_mux_tree_lock(struct i2c_adapter *adap)
> +{
> + if (i2c_parent_is_i2c_adapter(adap))
> + i2c_mux_tree_lock(to_i2c_adapter(adap->dev.parent));
> + else
> + i2c_lock_adapter(adap);
> +}
> +
> +static int i2c_mux_tree_trylock(struct i2c_adapter *adap)
> +{
> + int ret;
> + struct i2c_adapter *parent;
> +
> + if (i2c_parent_is_i2c_adapter(adap)) {
> + parent = to_i2c_adapter(adap->dev.parent);
> + ret = i2c_mux_tree_trylock(parent);
> + } else {
> + ret = i2c_trylock_adapter(adap);
> + }
> +
> + return ret;
> +}
> +
> +static void i2c_mux_tree_unlock(struct i2c_adapter *adap)
> +{
> + if (i2c_parent_is_i2c_adapter(adap))
> + i2c_mux_tree_unlock(to_i2c_adapter(adap->dev.parent));
> + else
> + i2c_unlock_adapter(adap);
> }
>
> /**
> @@ -1104,12 +1183,12 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> #endif
>
> if (in_atomic() || irqs_disabled()) {
> - ret = rt_mutex_trylock(&adap->bus_lock);
> + ret = i2c_mux_tree_trylock(adap);
> if (!ret)
> /* I2C activity is ongoing. */
> return -EAGAIN;
> } else {
> - rt_mutex_lock(&adap->bus_lock);
> + i2c_mux_tree_lock(adap);
> }
>
> /* Retry automatically on arbitration loss */
> @@ -1121,7 +1200,7 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> if (time_after(jiffies, orig_jiffies + adap->timeout))
> break;
> }
> - rt_mutex_unlock(&adap->bus_lock);
> + i2c_mux_tree_unlock(adap);
>
> return ret;
> } else {
> @@ -1857,7 +1936,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
> flags &= I2C_M_TEN | I2C_CLIENT_PEC;
>
> if (adapter->algo->smbus_xfer) {
> - rt_mutex_lock(&adapter->bus_lock);
> + i2c_mux_tree_lock(adapter);
>
> /* Retry automatically on arbitration loss */
> orig_jiffies = jiffies;
> @@ -1871,7 +1950,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
> orig_jiffies + adapter->timeout))
> break;
> }
> - rt_mutex_unlock(&adapter->bus_lock);
> + i2c_mux_tree_unlock(adapter);
> } else
> res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
> command, protocol, data);
I'm worried that this approach is risky. We now use i2c_mux_tree_*lock
internally, but still expose the i2c_*lock_adapter() API externally.
This API is _not_ mux-aware, and will do the wrong thing if called on a
bus segment behind a mux.
I'd rather not have two APIs when we really only need one. Let's just
update the current public API to be mux-aware, and use that everywhere.
> diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
> index f4110aa..da5327f 100755
> --- a/drivers/i2c/i2c-dev.c
> +++ b/drivers/i2c/i2c-dev.c
> @@ -193,12 +193,56 @@ static int i2cdev_check(struct device *dev, void *addrp)
> return dev->driver ? -EBUSY : 0;
> }
>
> +static int i2cdev_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
> +{
> + return adapter->dev.parent != NULL
> + && adapter->dev.parent->bus == &i2c_bus_type;
> +}
This is an exact duplicate of the same function in i2c-core. I'd rather
make it an inline function in <linux/i2c.h>, or export the one from
i2c-core.c. We have enough duplicate code in i2c-dev.c already :(
> +
> +/* walk up mux tree */
> +static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
> +{
> + int result;
> +
> + result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
> +
> + if (!result && i2cdev_parent_is_i2c_adapter(adapter))
> + result = i2cdev_check_mux_parents(
> + to_i2c_adapter(adapter->dev.parent), addr);
> +
> + return result;
> +}
> +
> +/* recurse down mux tree */
> +static int i2cdev_check_mux_childs(struct i2c_adapter *adapter, int addr)
children
> +{
> + int result = 0;
> + struct i2c_adapter *child, *next;
> +
> + list_for_each_entry_safe(child, next, &adapter->mux_list_head,
> + mux_list) {
> + result = device_for_each_child(&child->dev, &addr,
> + i2cdev_check);
> + if (result)
> + break;
> + result = i2cdev_check_mux_childs(child, addr);
Same as in the i2c-core variant, this value is ignored, I think this
isn't correct.
> + }
> + return result;
> +}
> +
> /* This address checking function differs from the one in i2c-core
> in that it considers an address with a registered device, but no
> driver bound to it, as NOT busy. */
> static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
> {
> - return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
> + int result;
> +
> + result = i2cdev_check_mux_parents(adapter, addr);
> +
> + if (!result)
> + result = i2cdev_check_mux_childs(adapter, addr);
> +
> + return result;
> }
>
> static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
> diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
> new file mode 100755
> index 0000000..f88d29a
> --- /dev/null
> +++ b/drivers/i2c/i2c-mux.c
> @@ -0,0 +1,184 @@
> +/*
> + * Multiplexed I2C bus driver.
> + *
> + * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
> + * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
> + *
> + * 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-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
> + * i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
> + * i2c-virtual.c from Brian Kuschak <bkuschak-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>
> + *
> + * 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.
> + */
> +
> +/* Adapted to kernel 2.6.33 by Michael Lawnick <michael.lawnick.ext@nsn.com> */
I'd rather have you add your copyright with the other ones already
present above.
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/i2c.h>
> +#include <linux/i2c-mux.h>
> +
> +/* multiplexer per channel data */
> +struct i2c_mux_priv {
> + struct i2c_adapter adap;
> + struct i2c_algorithm algo;
> +
> + struct i2c_adapter *parent;
> + void *mux_dev; /* the mux chip/device */
> + u32 chan_id; /* the channel id */
> +
> + int (*select)(struct i2c_adapter *adap, void *mux_dev, u32 chan_id);
> + int (*deselect)(struct i2c_adapter *adap, void *mux_dev, u32 chan_id);
The two "adap" can go away... I insisted on having parameter names for
the other two; for structures, it's usually pretty clear what we're
talking about.
> +};
> +
> +#define VIRT_TIMEOUT (HZ/2)
> +#define VIRT_RETRIES 3
These two are no longer used and can thus be deleted.
> +
> +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_adapter *parent = priv->parent;
> + int ret;
> +
> + /* Switch to the right mux port and perform the transfer.*/
Missing space at end of comment.
> +
> + ret = priv->select(parent, priv->mux_dev, priv->chan_id);
> + if (ret >= 0)
> + ret = parent->algo->master_xfer(parent, msgs, num);
> + if (priv->deselect)
> + priv->deselect(parent, priv->mux_dev, 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_adapter *parent = priv->parent;
> + int ret;
> +
> + /* Select the right mux port and perform the transfer.*/
Ditto.
> +
> + ret = priv->select(parent, priv->mux_dev, priv->chan_id);
> + if (ret >= 0)
> + ret = parent->algo->smbus_xfer(parent, addr, flags,
> + read_write, command, size, data);
Strange alignment.
> + if (priv->deselect)
> + priv->deselect(parent, priv->mux_dev, priv->chan_id);
> +
> + return ret;
> +}
> +
> +/* Return the parent's functionality for the virtual adapter */
Please avoid referring to "virtual adapters". The fact here is that all
bus segments of a given tree share the same functionality, because it
is a characteristic of the controller - nothing virtual here.
> +static u32 i2c_mux_functionality(struct i2c_adapter *adap)
> +{
> + struct i2c_mux_priv *priv = adap->algo_data;
> + struct i2c_adapter *parent = priv->parent;
> +
> + return parent->algo->functionality(parent);
> +}
> +
> +struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
> + void *mux_dev, u32 force_nr, u32 chan_id,
> + int (*select) (struct i2c_adapter *,
> + void *, u32),
> + int (*deselect) (struct i2c_adapter *,
> + void *, u32))
> +{
> + struct i2c_mux_priv *priv;
> + int ret;
> +
> + priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
> + if (!priv)
> + return NULL;
> +
> + /* Set up private adapter data */
> + priv->parent = parent;
> + priv->mux_dev = mux_dev;
> + priv->chan_id = chan_id;
> + priv->select = select;
> + priv->deselect = deselect;
> +
> + /* 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)
> + priv->algo.master_xfer = i2c_mux_master_xfer;
> + if (parent->algo->smbus_xfer)
> + 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);
I'm only half happy with this name. One problem is that it isn't
unique: if you have 2 mux chips on the same root segment, this will
lead to duplicate segments with the same name. Another problem is that
it completely hides the name of the controller (which, I admit, we may
recover by walking sysfs, but still...)
This isn't a blocker point, but something to keep in mind for further
improvements. It might even make sense to let the caller provide the
format for the segment names.
> + priv->adap.owner = THIS_MODULE;
> + priv->adap.id = parent->id;
> + priv->adap.algo = &priv->algo;
> + priv->adap.algo_data = priv;
> + priv->adap.dev.parent = &parent->dev;
> +
> + if (force_nr) {
> + priv->adap.nr = force_nr;
> + ret = i2c_add_numbered_adapter(&priv->adap);
> + } else {
> + ret = i2c_add_adapter(&priv->adap);
> + }
> + if (ret < 0) {
> + dev_err(&parent->dev, "failed to add mux-adapter (error=%d)\n",
> + ret);
> + kfree(priv);
> + return NULL;
> + }
> +
> + list_add_tail(&priv->adap.mux_list, &parent->mux_list_head);
The driver core maintains a device tree already, do you really need to
keep your own? We've tried hard to remove all redundancy between
i2c-core and the driver core in the last couple years, so I really would
like us to not add such redundancy back now.
If you have a good reason to have your own list, please explain. If
not, please get rid of it.
> +
> + dev_info(&parent->dev, "i2c-mux-%d: Multiplexed I2C bus on "
> + "parent bus i2c-%d, chan_id %d\n",
> + i2c_adapter_id(&priv->adap), i2c_adapter_id(parent), chan_id);
Have you looked at the output? I expect some redundancy, as you use
dev_info() on the parent, i2c_adapter_id(parent) is already included. I
think I'd rather call dev_info() on the newly spawned child, so you can
get rid of the leading "i2c-mux-%d". BTW, please use dev_name() instead
of hard-coding i2c-%d for the parent.
> +
> + return &priv->adap;
> +}
> +EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
> +
> +int i2c_del_mux_adapter(struct i2c_adapter *adap)
> +{
> + struct i2c_mux_priv *priv = adap->algo_data;
> + int ret;
> + struct i2c_adapter *child, *next, *parent;
Would look nicer with all structs in front and ret last, IMHO.
> +
> + if (adap->dev.parent != NULL
> + && adap->dev.parent->bus == &i2c_bus_type) {
This is a copy of i2c_parent_is_i2c_adapter(), isn't it? That's one
more reason to export it from i2c-core.
> + parent = to_i2c_adapter(adap->dev.parent);
Note that we could have i2c_parent_is_i2c_adapter() return the parent
adapter, if it proves useful in practice.
> + list_for_each_entry_safe(child, next, &parent->mux_list_head,
> + mux_list) {
> + if (child == adap) {
> + list_del(&child->mux_list);
> + break;
> + }
> + }
> + }
That being said... Using the driver core's list would save you the
hassle altogether.
> +
> + ret = i2c_del_adapter(adap);
> + if (ret < 0)
> + return ret;
> + kfree(priv);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
> +
> +MODULE_AUTHOR("Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>");
> +MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
> new file mode 100755
> index 0000000..0d5d6c8
> --- /dev/null
> +++ b/include/linux/i2c-mux.h
> @@ -0,0 +1,46 @@
> +/*
> + *
> + * i2c-mux.h - functions for the i2c-bus mux support
> + *
> + * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
> + * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
> + * Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#ifndef _LINUX_I2C_MUX_H
> +#define _LINUX_I2C_MUX_H
> +
> +#ifdef __KERNEL__
> +
> +/*
> + * Called to create a i2c bus on a multiplexed bus segment.
> + * The mux_dev and chan_id parameters are passed to the select
> + * and deselect callback functions to perform hardware-specific
> + * mux control.
> + */
> +struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
> + void *mux_dev, u32 force_nr, u32 chan_id,
> + int (*select) (struct i2c_adapter *adap,
> + void *mux_dev, u32 chan_id),
> + int (*deselect) (struct i2c_adapter *,
> + void *mux_dev, u32 chan_id));
> +
> +int i2c_del_mux_adapter(struct i2c_adapter *adap);
> +
> +#endif /* __KERNEL__ */
> +
> +#endif /* _LINUX_I2C_H */
You actually mean /* _LINUX_I2C_MUX_H */.
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index 1fd7b12..898a8c1 100755
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -349,6 +349,8 @@ struct i2c_adapter {
> struct completion dev_released;
>
> struct list_head userspace_clients;
> + struct list_head mux_list_head;
> + struct list_head mux_list;
As said before, I would much prefer if we didn't have to introduce
these.
> };
> #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
>
> @@ -380,6 +382,15 @@ static inline void i2c_unlock_adapter(struct i2c_adapter *adapter)
> rt_mutex_unlock(&adapter->bus_lock);
> }
>
> +/**
> + * i2c_trylock_adapter - Try to prevent access to an I2C bus segment
> + * @adapter: Target I2C bus segment
> + */
> +static inline int i2c_trylock_adapter(struct i2c_adapter *adapter)
> +{
> + return rt_mutex_trylock(&adapter->bus_lock);
> +}
> +
> /*flags for the client struct: */
> #define I2C_CLIENT_PEC 0x04 /* Use Packet Error Checking */
> #define I2C_CLIENT_TEN 0x10 /* we have a ten bit chip address */
Thanks,
--
Jean Delvare
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <20100610152411.5497461c-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
@ 2010-06-11 6:31 ` Michael Lawnick
[not found] ` <4C11D85F.7010604-Mmb7MZpHnFY@public.gmane.org>
2010-06-15 8:52 ` Michael Lawnick
1 sibling, 1 reply; 20+ messages in thread
From: Michael Lawnick @ 2010-06-11 6:31 UTC (permalink / raw)
To: Jean Delvare; +Cc: Linux I2C, Rodolfo Giometti
Hi,
beside all the other issues,
Jean Delvare said the following:
> Hi Michael,
>
>> + list_add_tail(&priv->adap.mux_list, &parent->mux_list_head);
>
> The driver core maintains a device tree already, do you really need to
> keep your own? We've tried hard to remove all redundancy between
> i2c-core and the driver core in the last couple years, so I really would
> like us to not add such redundancy back now.
>
> If you have a good reason to have your own list, please explain. If
> not, please get rid of it.
>
this is a core part of mux management. You need it for checking whether
the current client that is to be added is already present.
The problem is to efficiently parse down a mux tree towards the leaves.
Sub-muxes are registered as i2c clients to their upper bus. I found no way
to separate muxes from normal clients. So there were two ideas:
invent a client-type field in i2c-client or to hold a separate list.
The first one e.g. would have the possibility to provide basic info in sysFs
but I feared a general debate. So I decided to go the other way which is
hidden to the outer world.
If you don't like this way, I'd need some ideas how to do it.
--
KR
Michael
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4C11D85F.7010604-Mmb7MZpHnFY@public.gmane.org>
@ 2010-06-11 9:40 ` Jean Delvare
[not found] ` <20100611114003.01c15f62-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
0 siblings, 1 reply; 20+ messages in thread
From: Jean Delvare @ 2010-06-11 9:40 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Rodolfo Giometti
Hi Michael,
On Fri, 11 Jun 2010 08:31:59 +0200, Michael Lawnick wrote:
> Jean Delvare said the following:
> > Hi Michael,
> >
> >> + list_add_tail(&priv->adap.mux_list, &parent->mux_list_head);
> >
> > The driver core maintains a device tree already, do you really need to
> > keep your own? We've tried hard to remove all redundancy between
> > i2c-core and the driver core in the last couple years, so I really would
> > like us to not add such redundancy back now.
> >
> > If you have a good reason to have your own list, please explain. If
> > not, please get rid of it.
> >
> this is a core part of mux management. You need it for checking whether
> the current client that is to be added is already present.
> The problem is to efficiently parse down a mux tree towards the leaves.
> Sub-muxes are registered as i2c clients to their upper bus.
This is correct, but irrelevant, as far as I can see. When walking an
I2C segment tree towards the leaves, you care about the segments
themselves (struct i2c_adapter), not the mux chips. In your
architecture, muxed segments are direct children of the root segment
from the device tree perspective, not children of the mux chip.
> I found no way to separate muxes from normal clients.
If you have to, it is easy, the driver core has support for this
already. Search for i2c_client_type and i2c_adapter_type in i2c-core.c.
We could add i2c_mux_type easily. But as I wrote above, I don't think
we need this.
> So there were two ideas:
> invent a client-type field in i2c-client or to hold a separate list.
> The first one e.g. would have the possibility to provide basic info in sysFs
> but I feared a general debate. So I decided to go the other way which is
> hidden to the outer world.
>
> If you don't like this way, I'd need some ideas how to do it.
I would walk the device tree maintained by the driver core (using
device_for_each_child) and filtering out irrelevant devices. Basically
filtering on dev->type == &i2c_adapter_type should do the trick,
methinks. Is there anything I am missing?
Thanks,
--
Jean Delvare
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x
[not found] ` <4BE01795.1090605-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:52 ` Rodolfo Giometti
2010-06-09 16:41 ` Jean Delvare
@ 2010-06-13 12:11 ` Jean Delvare
[not found] ` <20100613141122.1d5b1423-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2 siblings, 1 reply; 20+ messages in thread
From: Jean Delvare @ 2010-06-13 12:11 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Rodolfo Giometti
Hi Michael,
I just hit a bug...
On Tue, 04 May 2010 14:48:21 +0200, Michael Lawnick wrote:
> +static int pca954x_select_chan(struct i2c_adapter *adap,
> + void *client, u32 chan)
> +{
> + struct pca954x *data = i2c_get_clientdata(client);
> + const struct chip_desc *chip = &chips[data->type];
> + u8 regval;
> + int ret = 0;
> +
> + /* we make switches look like muxes, not sure how to be smarter */
> + if (chip->muxtype == pca954x_ismux)
> + regval = chan | chip->enable;
> + else
> + regval = 1 << chan;
> +
> + /* Only select the channel if its different from the last channel */
> + if (data->last_chan != chan) {
That's not right. data->last_chan is 0 after initialization or
deselection, but selecting channel 0 is valid and must be possible.
So you either want to use a different initialization value (e.g. 0xff)
or store the register value in data->last_chan instead of the channel
number. I went for the latter.
> + ret = pca954x_reg_write(adap, client, regval);
> + data->last_chan = chan;
> + }
> +
> + return ret;
> +}
--
Jean Delvare
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x
[not found] ` <20100613141122.1d5b1423-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
@ 2010-06-14 9:09 ` Michael Lawnick
0 siblings, 0 replies; 20+ messages in thread
From: Michael Lawnick @ 2010-06-14 9:09 UTC (permalink / raw)
To: Jean Delvare; +Cc: Linux I2C, Rodolfo Giometti
Jean Delvare said the following:
> Hi Michael,
>
> I just hit a bug...
>
> On Tue, 04 May 2010 14:48:21 +0200, Michael Lawnick wrote:
>> +static int pca954x_select_chan(struct i2c_adapter *adap,
>> + void *client, u32 chan)
>> +{
>> + struct pca954x *data = i2c_get_clientdata(client);
>> + const struct chip_desc *chip = &chips[data->type];
>> + u8 regval;
>> + int ret = 0;
>> +
>> + /* we make switches look like muxes, not sure how to be smarter */
>> + if (chip->muxtype == pca954x_ismux)
>> + regval = chan | chip->enable;
>> + else
>> + regval = 1 << chan;
>> +
>> + /* Only select the channel if its different from the last channel */
>> + if (data->last_chan != chan) {
>
> That's not right. data->last_chan is 0 after initialization or
> deselection, but selecting channel 0 is valid and must be possible.
>
> So you either want to use a different initialization value (e.g. 0xff)
> or store the register value in data->last_chan instead of the channel
> number. I went for the latter.
ACK
--
KR
Michael
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <20100610152411.5497461c-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2010-06-11 6:31 ` Michael Lawnick
@ 2010-06-15 8:52 ` Michael Lawnick
[not found] ` <4C173F61.8000007-Mmb7MZpHnFY@public.gmane.org>
1 sibling, 1 reply; 20+ messages in thread
From: Michael Lawnick @ 2010-06-15 8:52 UTC (permalink / raw)
To: Jean Delvare; +Cc: Linux I2C
Hi Jean,
Jean Delvare said the following:
...
>> if (adapter->algo->smbus_xfer) {
>> - rt_mutex_lock(&adapter->bus_lock);
>> + i2c_mux_tree_lock(adapter);
>>
>> /* Retry automatically on arbitration loss */
>> orig_jiffies = jiffies;
>> @@ -1871,7 +1950,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
>> orig_jiffies + adapter->timeout))
>> break;
>> }
>> - rt_mutex_unlock(&adapter->bus_lock);
>> + i2c_mux_tree_unlock(adapter);
>> } else
>> res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
>> command, protocol, data);
>
> I'm worried that this approach is risky. We now use i2c_mux_tree_*lock
> internally, but still expose the i2c_*lock_adapter() API externally.
> This API is _not_ mux-aware, and will do the wrong thing if called on a
> bus segment behind a mux.
>
> I'd rather not have two APIs when we really only need one. Let's just
> update the current public API to be mux-aware, and use that everywhere.
Agree, but I'd vote to do it not inline as its now. Otherwise we start to export
mux implementation details in i2c.h
>
>> diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
>> index f4110aa..da5327f 100755
>> --- a/drivers/i2c/i2c-dev.c
>> +++ b/drivers/i2c/i2c-dev.c
>> @@ -193,12 +193,56 @@ static int i2cdev_check(struct device *dev, void *addrp)
>> return dev->driver ? -EBUSY : 0;
>> }
>>
>> +static int i2cdev_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
>> +{
>> + return adapter->dev.parent != NULL
>> + && adapter->dev.parent->bus == &i2c_bus_type;
>> +}
>
> This is an exact duplicate of the same function in i2c-core. I'd rather
> make it an inline function in <linux/i2c.h>, or export the one from
> i2c-core.c. We have enough duplicate code in i2c-dev.c already :(
Must this and the above be done in an extra patch or can it be mixed into this mux patch?
--
KR
Michael
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <20100611114003.01c15f62-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
@ 2010-06-15 8:53 ` Michael Lawnick
0 siblings, 0 replies; 20+ messages in thread
From: Michael Lawnick @ 2010-06-15 8:53 UTC (permalink / raw)
To: Jean Delvare; +Cc: Linux I2C
Hi Jean,
Jean Delvare said the following:
> > Hi Michael,
...
> > I would walk the device tree maintained by the driver core (using
> > device_for_each_child) and filtering out irrelevant devices. Basically
> > filtering on dev->type == &i2c_adapter_type should do the trick,
> > methinks.
> >
You are right, I missed that somehow when investigating for a solution.
Until your post I was convinced that the adapters are all registered to
bus only. I now rechecked by some small code and found that I can throw
away these awefull lists.
Iteration will follow.
-- KR Michael
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4C173F61.8000007-Mmb7MZpHnFY@public.gmane.org>
@ 2010-06-15 9:00 ` Jean Delvare
0 siblings, 0 replies; 20+ messages in thread
From: Jean Delvare @ 2010-06-15 9:00 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C
Hi Michael,
On Tue, 15 Jun 2010 10:52:49 +0200, Michael Lawnick wrote:
> Hi Jean,
>
> Jean Delvare said the following:
> ...
> >> if (adapter->algo->smbus_xfer) {
> >> - rt_mutex_lock(&adapter->bus_lock);
> >> + i2c_mux_tree_lock(adapter);
> >>
> >> /* Retry automatically on arbitration loss */
> >> orig_jiffies = jiffies;
> >> @@ -1871,7 +1950,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
> >> orig_jiffies + adapter->timeout))
> >> break;
> >> }
> >> - rt_mutex_unlock(&adapter->bus_lock);
> >> + i2c_mux_tree_unlock(adapter);
> >> } else
> >> res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
> >> command, protocol, data);
> >
> > I'm worried that this approach is risky. We now use i2c_mux_tree_*lock
> > internally, but still expose the i2c_*lock_adapter() API externally.
> > This API is _not_ mux-aware, and will do the wrong thing if called on a
> > bus segment behind a mux.
> >
> > I'd rather not have two APIs when we really only need one. Let's just
> > update the current public API to be mux-aware, and use that everywhere.
>
> Agree, but I'd vote to do it not inline as its now. Otherwise we start to export
> mux implementation details in i2c.h
Of course. In fact I am preparing a patch which moves these functions
to i2c-core, uninlines them, and uses them as appropriate. Your
multiplexing patch would stack on top of it, so it is nice and clean
and self-contained.
> >> diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
> >> index f4110aa..da5327f 100755
> >> --- a/drivers/i2c/i2c-dev.c
> >> +++ b/drivers/i2c/i2c-dev.c
> >> @@ -193,12 +193,56 @@ static int i2cdev_check(struct device *dev, void *addrp)
> >> return dev->driver ? -EBUSY : 0;
> >> }
> >>
> >> +static int i2cdev_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
> >> +{
> >> + return adapter->dev.parent != NULL
> >> + && adapter->dev.parent->bus == &i2c_bus_type;
> >> +}
> >
> > This is an exact duplicate of the same function in i2c-core. I'd rather
> > make it an inline function in <linux/i2c.h>, or export the one from
> > i2c-core.c. We have enough duplicate code in i2c-dev.c already :(
>
> Must this and the above be done in an extra patch or can it be mixed into this mux patch?
Whatever is easier for you, both are fine with me.
--
Jean Delvare
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4BE014ED.9070907-Mmb7MZpHnFY@public.gmane.org>
@ 2010-05-04 15:19 ` Yegor Yefremov
0 siblings, 0 replies; 20+ messages in thread
From: Yegor Yefremov @ 2010-05-04 15:19 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Delvare, Jean, Rodolfo Giometti
On Tue, May 4, 2010 at 2:37 PM, Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org> wrote:
> Seems like Thunderbird isn't usable for sending patches :-(
> Trying again with attachment.
Have you tried External Editor with VIM:
http://globs.org/articles.php?pg=2&lng=en
For me it is working like a charm.
Regards,
Yegor
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4BE01321.3060704-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:33 ` Rodolfo Giometti
@ 2010-05-04 12:37 ` Michael Lawnick
[not found] ` <4BE014ED.9070907-Mmb7MZpHnFY@public.gmane.org>
1 sibling, 1 reply; 20+ messages in thread
From: Michael Lawnick @ 2010-05-04 12:37 UTC (permalink / raw)
To: Linux I2C; +Cc: Delvare, Jean , Rodolfo Giometti
Seems like Thunderbird isn't usable for sending patches :-(
Trying again with attachment.
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
[not found] ` <4BE01321.3060704-Mmb7MZpHnFY@public.gmane.org>
@ 2010-05-04 12:33 ` Rodolfo Giometti
2010-05-04 12:37 ` Michael Lawnick
1 sibling, 0 replies; 20+ messages in thread
From: Rodolfo Giometti @ 2010-05-04 12:33 UTC (permalink / raw)
To: Michael Lawnick; +Cc: Linux I2C, Delvare, Jean
On Tue, May 04, 2010 at 02:29:21PM +0200, Michael Lawnick wrote:
> Add multiplexed bus core support. I2C multiplexer and switches
> like pca954x instantiate new adapters per output.
>
> Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
Acked-by: Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
--
GNU/Linux Solutions e-mail: giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org
Linux Device Driver giometti-k2GhghHVRtY@public.gmane.org
Embedded Systems phone: +39 349 2432127
UNIX programming skype: rodolfo.giometti
Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it
^ permalink raw reply [flat|nested] 20+ messages in thread
* [PATCH v2 1/2] i2c: Multiplexed I2C bus core support
@ 2010-05-04 12:29 Michael Lawnick
[not found] ` <4BE01321.3060704-Mmb7MZpHnFY@public.gmane.org>
0 siblings, 1 reply; 20+ messages in thread
From: Michael Lawnick @ 2010-05-04 12:29 UTC (permalink / raw)
To: Linux I2C; +Cc: Delvare, Jean , Rodolfo Giometti
Add multiplexed bus core support. I2C multiplexer and switches
like pca954x instantiate new adapters per output.
Signed-off-by: Michael Lawnick <ml.lawnick-Mmb7MZpHnFY@public.gmane.org>
---
Based on kernel 2.6.33 +
[PATCH] i2c-core: Use per-adapter userspace device lists
by Jean Delware <20100424201914.08b3f008-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
<http://article.gmane.org/gmane.linux.drivers.i2c/5994/>
From 1d17617d8845f2268d4123ec0cf5310743303d45 Mon Sep 17 00:00:00 2001
From: Michael Lawnick <demx1175@demmc3qc.(none)>
Date: Tue, 4 May 2010 13:34:52 +0200
Subject: [PATCH] mux_core_support
---
drivers/i2c/Kconfig | 8 ++
drivers/i2c/Makefile | 1 +
drivers/i2c/i2c-core.c | 93 ++++++++++++++++++++++--
drivers/i2c/i2c-dev.c | 46 ++++++++++++-
drivers/i2c/i2c-mux.c | 184
+++++++++++++++++++++++++++++++++++++++++++++++
include/linux/i2c-mux.h | 46 ++++++++++++
include/linux/i2c.h | 11 +++
7 files changed, 381 insertions(+), 8 deletions(-)
create mode 100755 drivers/i2c/i2c-mux.c
create mode 100755 include/linux/i2c-mux.h
diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 8d8a00e..2cd6d78 100755
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -36,6 +36,14 @@ config I2C_COMPAT
other user-space package which expects i2c adapters to be class
devices. If you don't know, say Y.
+config I2C_MUX
+ tristate "I2C bus multiplexing support"
+ depends on I2C
+ help
+ Say Y here if you want the I2C core to support the ability to
+ handle multiplexed I2C bus topologies, by presenting each
+ multiplexed segment as a I2C adapter.
+
config I2C_CHARDEV
tristate "I2C device interface"
help
diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index ba26e6c..a488e8b 100755
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -5,6 +5,7 @@
obj-$(CONFIG_I2C_BOARDINFO) += i2c-boardinfo.o
obj-$(CONFIG_I2C) += i2c-core.o
obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
+obj-$(CONFIG_I2C_MUX) += i2c-mux.o
obj-y += busses/ chips/ algos/
ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index fc93e28..682966a 100755
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -20,7 +20,10 @@
/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
SMBus 2.0 support by Mark Studebaker <mdsxyz123-/E1597aS9LQAvxtiuMwx3w@public.gmane.org> and
- Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org> */
+ Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
+ Mux support by Rodolfo Giometti <giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org> and
+ Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org> */
+
#include <linux/module.h>
#include <linux/kernel.h>
@@ -288,6 +291,12 @@ struct i2c_client *i2c_verify_client(struct device
*dev)
}
EXPORT_SYMBOL(i2c_verify_client);
+static int i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
+{
+ return adapter->dev.parent != NULL
+ && adapter->dev.parent->bus == &i2c_bus_type;
+}
+
/**
* i2c_new_device - instantiate an i2c device
@@ -624,6 +633,7 @@ static int i2c_register_adapter(struct i2c_adapter
*adap)
rt_mutex_init(&adap->bus_lock);
INIT_LIST_HEAD(&adap->userspace_clients);
+ INIT_LIST_HEAD(&adap->mux_list_head);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
@@ -949,9 +959,78 @@ static int __i2c_check_addr(struct device *dev,
void *addrp)
return 0;
}
+/* walk up mux tree */
+static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+ int result;
+
+ result = device_for_each_child(&adapter->dev, &addr, __i2c_check_addr);
+
+ if (!result && i2c_parent_is_i2c_adapter(adapter))
+ result = i2c_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ return result;
+}
+
+/* recurse down mux tree */
+static int i2c_check_mux_childs(struct i2c_adapter *adapter, int addr)
+{
+ int result = 0;
+ struct i2c_adapter *child, *next;
+
+ list_for_each_entry_safe(child, next, &adapter->mux_list_head,
+ mux_list) {
+ result = device_for_each_child(&child->dev, &addr,
+ __i2c_check_addr);
+ if (result)
+ break;
+ result = i2c_check_mux_childs(child, addr);
+ }
+ return result;
+}
+
static int i2c_check_addr(struct i2c_adapter *adapter, int addr)
{
- return device_for_each_child(&adapter->dev, &addr, __i2c_check_addr);
+ int result;
+
+ result = i2c_check_mux_parents(adapter, addr);
+
+ if (!result)
+ result = i2c_check_mux_childs(adapter, addr);
+
+ return result;
+}
+
+static void i2c_mux_tree_lock(struct i2c_adapter *adap)
+{
+ if (i2c_parent_is_i2c_adapter(adap))
+ i2c_mux_tree_lock(to_i2c_adapter(adap->dev.parent));
+ else
+ i2c_lock_adapter(adap);
+}
+
+static int i2c_mux_tree_trylock(struct i2c_adapter *adap)
+{
+ int ret;
+ struct i2c_adapter *parent;
+
+ if (i2c_parent_is_i2c_adapter(adap)) {
+ parent = to_i2c_adapter(adap->dev.parent);
+ ret = i2c_mux_tree_trylock(parent);
+ } else {
+ ret = i2c_trylock_adapter(adap);
+ }
+
+ return ret;
+}
+
+static void i2c_mux_tree_unlock(struct i2c_adapter *adap)
+{
+ if (i2c_parent_is_i2c_adapter(adap))
+ i2c_mux_tree_unlock(to_i2c_adapter(adap->dev.parent));
+ else
+ i2c_unlock_adapter(adap);
}
/**
@@ -1104,12 +1183,12 @@ int i2c_transfer(struct i2c_adapter *adap,
struct i2c_msg *msgs, int num)
#endif
if (in_atomic() || irqs_disabled()) {
- ret = rt_mutex_trylock(&adap->bus_lock);
+ ret = i2c_mux_tree_trylock(adap);
if (!ret)
/* I2C activity is ongoing. */
return -EAGAIN;
} else {
- rt_mutex_lock(&adap->bus_lock);
+ i2c_mux_tree_lock(adap);
}
/* Retry automatically on arbitration loss */
@@ -1121,7 +1200,7 @@ int i2c_transfer(struct i2c_adapter *adap, struct
i2c_msg *msgs, int num)
if (time_after(jiffies, orig_jiffies + adap->timeout))
break;
}
- rt_mutex_unlock(&adap->bus_lock);
+ i2c_mux_tree_unlock(adap);
return ret;
} else {
@@ -1857,7 +1936,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter,
u16 addr, unsigned short flags,
flags &= I2C_M_TEN | I2C_CLIENT_PEC;
if (adapter->algo->smbus_xfer) {
- rt_mutex_lock(&adapter->bus_lock);
+ i2c_mux_tree_lock(adapter);
/* Retry automatically on arbitration loss */
orig_jiffies = jiffies;
@@ -1871,7 +1950,7 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter,
u16 addr, unsigned short flags,
orig_jiffies + adapter->timeout))
break;
}
- rt_mutex_unlock(&adapter->bus_lock);
+ i2c_mux_tree_unlock(adapter);
} else
res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,
command, protocol, data);
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index f4110aa..da5327f 100755
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -193,12 +193,56 @@ static int i2cdev_check(struct device *dev, void
*addrp)
return dev->driver ? -EBUSY : 0;
}
+static int i2cdev_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
+{
+ return adapter->dev.parent != NULL
+ && adapter->dev.parent->bus == &i2c_bus_type;
+}
+
+/* walk up mux tree */
+static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
+{
+ int result;
+
+ result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+
+ if (!result && i2cdev_parent_is_i2c_adapter(adapter))
+ result = i2cdev_check_mux_parents(
+ to_i2c_adapter(adapter->dev.parent), addr);
+
+ return result;
+}
+
+/* recurse down mux tree */
+static int i2cdev_check_mux_childs(struct i2c_adapter *adapter, int addr)
+{
+ int result = 0;
+ struct i2c_adapter *child, *next;
+
+ list_for_each_entry_safe(child, next, &adapter->mux_list_head,
+ mux_list) {
+ result = device_for_each_child(&child->dev, &addr,
+ i2cdev_check);
+ if (result)
+ break;
+ result = i2cdev_check_mux_childs(child, addr);
+ }
+ return result;
+}
+
/* This address checking function differs from the one in i2c-core
in that it considers an address with a registered device, but no
driver bound to it, as NOT busy. */
static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int
addr)
{
- return device_for_each_child(&adapter->dev, &addr, i2cdev_check);
+ int result;
+
+ result = i2cdev_check_mux_parents(adapter, addr);
+
+ if (!result)
+ result = i2cdev_check_mux_childs(adapter, addr);
+
+ return result;
}
static noinline int i2cdev_ioctl_rdrw(struct i2c_client *client,
diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
new file mode 100755
index 0000000..f88d29a
--- /dev/null
+++ b/drivers/i2c/i2c-mux.c
@@ -0,0 +1,184 @@
+/*
+ * Multiplexed I2C bus driver.
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
+ *
+ * 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-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
+ * i2c-virtual.c from Ken Harrenstien, Copyright (c) 2004 Google, Inc.
+ * i2c-virtual.c from Brian Kuschak <bkuschak-/E1597aS9LQAvxtiuMwx3w@public.gmane.org>
+ *
+ * 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.
+ */
+
+/* Adapted to kernel 2.6.33 by Michael Lawnick
<michael.lawnick.ext-OYasijW0DpE@public.gmane.org> */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+
+/* multiplexer per channel data */
+struct i2c_mux_priv {
+ struct i2c_adapter adap;
+ struct i2c_algorithm algo;
+
+ struct i2c_adapter *parent;
+ void *mux_dev; /* the mux chip/device */
+ u32 chan_id; /* the channel id */
+
+ int (*select)(struct i2c_adapter *adap, void *mux_dev, u32 chan_id);
+ int (*deselect)(struct i2c_adapter *adap, void *mux_dev, u32 chan_id);
+};
+
+#define VIRT_TIMEOUT (HZ/2)
+#define VIRT_RETRIES 3
+
+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_adapter *parent = priv->parent;
+ int ret;
+
+ /* Switch to the right mux port and perform the transfer.*/
+
+ ret = priv->select(parent, priv->mux_dev, priv->chan_id);
+ if (ret >= 0)
+ ret = parent->algo->master_xfer(parent, msgs, num);
+ if (priv->deselect)
+ priv->deselect(parent, priv->mux_dev, 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_adapter *parent = priv->parent;
+ int ret;
+
+ /* Select the right mux port and perform the transfer.*/
+
+ ret = priv->select(parent, priv->mux_dev, priv->chan_id);
+ if (ret >= 0)
+ ret = parent->algo->smbus_xfer(parent, addr, flags,
+ read_write, command, size, data);
+ if (priv->deselect)
+ priv->deselect(parent, priv->mux_dev, priv->chan_id);
+
+ return ret;
+}
+
+/* Return the parent's functionality for the virtual adapter */
+static u32 i2c_mux_functionality(struct i2c_adapter *adap)
+{
+ struct i2c_mux_priv *priv = adap->algo_data;
+ struct i2c_adapter *parent = priv->parent;
+
+ return parent->algo->functionality(parent);
+}
+
+struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
+ void *mux_dev, u32 force_nr, u32 chan_id,
+ int (*select) (struct i2c_adapter *,
+ void *, u32),
+ int (*deselect) (struct i2c_adapter *,
+ void *, u32))
+{
+ struct i2c_mux_priv *priv;
+ int ret;
+
+ priv = kzalloc(sizeof(struct i2c_mux_priv), GFP_KERNEL);
+ if (!priv)
+ return NULL;
+
+ /* Set up private adapter data */
+ priv->parent = parent;
+ priv->mux_dev = mux_dev;
+ priv->chan_id = chan_id;
+ priv->select = select;
+ priv->deselect = deselect;
+
+ /* 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)
+ priv->algo.master_xfer = i2c_mux_master_xfer;
+ if (parent->algo->smbus_xfer)
+ 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.id = parent->id;
+ priv->adap.algo = &priv->algo;
+ priv->adap.algo_data = priv;
+ priv->adap.dev.parent = &parent->dev;
+
+ if (force_nr) {
+ priv->adap.nr = force_nr;
+ ret = i2c_add_numbered_adapter(&priv->adap);
+ } else {
+ ret = i2c_add_adapter(&priv->adap);
+ }
+ if (ret < 0) {
+ dev_err(&parent->dev, "failed to add mux-adapter (error=%d)\n",
+ ret);
+ kfree(priv);
+ return NULL;
+ }
+
+ list_add_tail(&priv->adap.mux_list, &parent->mux_list_head);
+
+ dev_info(&parent->dev, "i2c-mux-%d: Multiplexed I2C bus on "
+ "parent bus i2c-%d, chan_id %d\n",
+ i2c_adapter_id(&priv->adap), i2c_adapter_id(parent), chan_id);
+
+ return &priv->adap;
+}
+EXPORT_SYMBOL_GPL(i2c_add_mux_adapter);
+
+int i2c_del_mux_adapter(struct i2c_adapter *adap)
+{
+ struct i2c_mux_priv *priv = adap->algo_data;
+ int ret;
+ struct i2c_adapter *child, *next, *parent;
+
+ if (adap->dev.parent != NULL
+ && adap->dev.parent->bus == &i2c_bus_type) {
+ parent = to_i2c_adapter(adap->dev.parent);
+ list_for_each_entry_safe(child, next, &parent->mux_list_head,
+ mux_list) {
+ if (child == adap) {
+ list_del(&child->mux_list);
+ break;
+ }
+ }
+ }
+
+ ret = i2c_del_adapter(adap);
+ if (ret < 0)
+ return ret;
+ kfree(priv);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(i2c_del_mux_adapter);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>");
+MODULE_DESCRIPTION("I2C driver for multiplexed I2C busses");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
new file mode 100755
index 0000000..0d5d6c8
--- /dev/null
+++ b/include/linux/i2c-mux.h
@@ -0,0 +1,46 @@
+/*
+ *
+ * i2c-mux.h - functions for the i2c-bus mux support
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti-k2GhghHVRtY@public.gmane.org>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info-ymFC7zkAqBI1GQ1Ptb7lUw@public.gmane.org>
+ * Michael Lawnick <michael.lawnick.ext-OYasijW0DpE@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _LINUX_I2C_MUX_H
+#define _LINUX_I2C_MUX_H
+
+#ifdef __KERNEL__
+
+/*
+ * Called to create a i2c bus on a multiplexed bus segment.
+ * The mux_dev and chan_id parameters are passed to the select
+ * and deselect callback functions to perform hardware-specific
+ * mux control.
+ */
+struct i2c_adapter *i2c_add_mux_adapter(struct i2c_adapter *parent,
+ void *mux_dev, u32 force_nr, u32 chan_id,
+ int (*select) (struct i2c_adapter *adap,
+ void *mux_dev, u32 chan_id),
+ int (*deselect) (struct i2c_adapter *,
+ void *mux_dev, u32 chan_id));
+
+int i2c_del_mux_adapter(struct i2c_adapter *adap);
+
+#endif /* __KERNEL__ */
+
+#endif /* _LINUX_I2C_H */
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 1fd7b12..898a8c1 100755
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -349,6 +349,8 @@ struct i2c_adapter {
struct completion dev_released;
struct list_head userspace_clients;
+ struct list_head mux_list_head;
+ struct list_head mux_list;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
@@ -380,6 +382,15 @@ static inline void i2c_unlock_adapter(struct
i2c_adapter *adapter)
rt_mutex_unlock(&adapter->bus_lock);
}
+/**
+ * i2c_trylock_adapter - Try to prevent access to an I2C bus segment
+ * @adapter: Target I2C bus segment
+ */
+static inline int i2c_trylock_adapter(struct i2c_adapter *adapter)
+{
+ return rt_mutex_trylock(&adapter->bus_lock);
+}
+
/*flags for the client struct: */
#define I2C_CLIENT_PEC 0x04 /* Use Packet Error Checking */
#define I2C_CLIENT_TEN 0x10 /* we have a ten bit chip address */
^ permalink raw reply related [flat|nested] 20+ messages in thread
end of thread, other threads:[~2010-06-15 9:00 UTC | newest]
Thread overview: 20+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2010-05-04 12:46 [PATCH v2 1/2] i2c: Multiplexed I2C bus core support Michael Lawnick
[not found] ` <4BE01741.1010909-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:48 ` [PATCH v2 2/2] i2c: Multiplexed I2C bus multiplexer driver pca954x Michael Lawnick
[not found] ` <4BE01795.1090605-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:52 ` Rodolfo Giometti
2010-06-09 16:41 ` Jean Delvare
[not found] ` <20100609184143.06488f2f-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2010-06-10 10:15 ` Michael Lawnick
2010-06-13 12:11 ` Jean Delvare
[not found] ` <20100613141122.1d5b1423-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2010-06-14 9:09 ` Michael Lawnick
2010-05-04 12:52 ` [PATCH v2 1/2] i2c: Multiplexed I2C bus core support Rodolfo Giometti
2010-05-17 7:36 ` Michael Lawnick
[not found] ` <4BF0F200.5090604-Mmb7MZpHnFY@public.gmane.org>
2010-05-17 8:15 ` Jean Delvare
2010-06-10 13:24 ` Jean Delvare
[not found] ` <20100610152411.5497461c-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2010-06-11 6:31 ` Michael Lawnick
[not found] ` <4C11D85F.7010604-Mmb7MZpHnFY@public.gmane.org>
2010-06-11 9:40 ` Jean Delvare
[not found] ` <20100611114003.01c15f62-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org>
2010-06-15 8:53 ` Michael Lawnick
2010-06-15 8:52 ` Michael Lawnick
[not found] ` <4C173F61.8000007-Mmb7MZpHnFY@public.gmane.org>
2010-06-15 9:00 ` Jean Delvare
-- strict thread matches above, loose matches on Subject: below --
2010-05-04 12:29 Michael Lawnick
[not found] ` <4BE01321.3060704-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 12:33 ` Rodolfo Giometti
2010-05-04 12:37 ` Michael Lawnick
[not found] ` <4BE014ED.9070907-Mmb7MZpHnFY@public.gmane.org>
2010-05-04 15:19 ` Yegor Yefremov
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