From e4a7b9b04de15f6b63da5ccdd373ffa3057a3681 Mon Sep 17 00:00:00 2001
From: Wolfram Sang <w.sang@pengutronix.de>
Date: Tue, 4 May 2010 11:09:27 +0200
Subject: [PATCH 1/3] i2c-core: Erase pointer to clientdata on removal
After discovering that a lot of i2c-drivers leave the pointer to their
clientdata dangling, it was decided to let the core handle this issue.
It is assumed that the core may access the private data after remove()
as there are no guarantees for the lifetime of such pointers anyhow (see
thread starting at http://lkml.org/lkml/2010/3/21/68)
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
Documentation/i2c/writing-clients | 5 +++++
drivers/i2c/i2c-core.c | 8 ++++++--
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/Documentation/i2c/writing-clients b/Documentation/i2c/writing-clients
index 3219ee0dbfef..5ebf5af1d716 100644
--- a/Documentation/i2c/writing-clients
+++ b/Documentation/i2c/writing-clients
@@ -74,6 +74,11 @@ structure at all. You should use this to keep device-specific data.
/* retrieve the value */
void *i2c_get_clientdata(const struct i2c_client *client);
+Note that starting with kernel 2.6.34, you don't have to set the `data' field
+to NULL in remove() or if probe() failed anymore. The i2c-core does this
+automatically on these occasions. Those are also the only times the core will
+touch this field.
+
Accessing the client
====================
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 3202a86f420e..b9306b1a6baa 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -117,8 +117,10 @@ static int i2c_device_probe(struct device *dev)
dev_dbg(dev, "probe\n");
status = driver->probe(client, i2c_match_id(driver->id_table, client));
- if (status)
+ if (status) {
client->driver = NULL;
+ i2c_set_clientdata(client, NULL);
+ }
return status;
}
@@ -139,8 +141,10 @@ static int i2c_device_remove(struct device *dev)
dev->driver = NULL;
status = 0;
}
- if (status == 0)
+ if (status == 0) {
client->driver = NULL;
+ i2c_set_clientdata(client, NULL);
+ }
return status;
}
From b1d4b390ea4bb480e65974ce522a04022608a8df Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Tue, 4 May 2010 11:09:28 +0200
Subject: [PATCH 2/3] i2c: Fix probing of FSC hardware monitoring chips
Some FSC hardware monitoring chips (Syleus at least) doesn't like
quick writes we typically use to probe for I2C chips. Use a regular
byte read instead for the address they live at (0x73). These are the
only known chips living at this address on PC systems.
For clarity, this fix should not be needed for kernels 2.6.30 and
later, as we started instantiating the hwmon devices explicitly based
on DMI data. Still, this fix is valuable in the following two cases:
* Support for recent FSC chips on older kernels. The DMI-based device
instantiation is more difficult to backport than the device support
itself.
* Case where the DMI-based device instantiation fails, whatever the
reason. We fall back to probing in that case, so it should work.
This fixes kernel bug #15634:
https://bugzilla.kernel.org/show_bug.cgi?id=15634
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Cc: stable@kernel.org
---
drivers/i2c/i2c-core.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index b9306b1a6baa..5105126225c3 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1264,12 +1264,23 @@ static int i2c_detect_address(struct i2c_client *temp_client,
return 0;
/* Make sure there is something at this address */
- if (i2c_smbus_xfer(adapter, addr, 0, 0, 0, I2C_SMBUS_QUICK, NULL) < 0)
- return 0;
+ if (addr == 0x73 && (adapter->class & I2C_CLASS_HWMON)) {
+ /* Special probe for FSC hwmon chips */
+ union i2c_smbus_data dummy;
- /* Prevent 24RF08 corruption */
- if ((addr & ~0x0f) == 0x50)
- i2c_smbus_xfer(adapter, addr, 0, 0, 0, I2C_SMBUS_QUICK, NULL);
+ if (i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_READ, 0,
+ I2C_SMBUS_BYTE_DATA, &dummy) < 0)
+ return 0;
+ } else {
+ if (i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_WRITE, 0,
+ I2C_SMBUS_QUICK, NULL) < 0)
+ return 0;
+
+ /* Prevent 24RF08 corruption */
+ if ((addr & ~0x0f) == 0x50)
+ i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_WRITE, 0,
+ I2C_SMBUS_QUICK, NULL);
+ }
/* Finally call the custom detection function */
memset(&info, 0, sizeof(struct i2c_board_info));
From 6629dcff19470a894ce294d0adb9cbab94ee1fb9 Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Tue, 4 May 2010 11:09:28 +0200
Subject: [PATCH 3/3] i2c-core: Use per-adapter userspace device lists
Using a single list for all userspace devices leads to a dead lock
on multiplexed buses in some circumstances (mux chip instantiated
from userspace). This is solved by using a separate list for each
bus segment.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Michael Lawnick <ml.lawnick@gmx.de>
---
drivers/i2c/i2c-core.c | 34 ++++++++++++++++++----------------
include/linux/i2c.h | 2 ++
2 files changed, 20 insertions(+), 16 deletions(-)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 5105126225c3..c2258a51fe0c 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -40,12 +40,11 @@
#include "i2c-core.h"
-/* core_lock protects i2c_adapter_idr, userspace_devices, and guarantees
+/* core_lock protects i2c_adapter_idr, and guarantees
that device detection, deletion of detected devices, and attach_adapter
and detach_adapter calls are serialized */
static DEFINE_MUTEX(core_lock);
static DEFINE_IDR(i2c_adapter_idr);
-static LIST_HEAD(userspace_devices);
static struct device_type i2c_client_type;
static int i2c_check_addr(struct i2c_adapter *adapter, int addr);
@@ -542,9 +541,9 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
return -EEXIST;
/* Keep track of the added device */
- mutex_lock(&core_lock);
- list_add_tail(&client->detected, &userspace_devices);
- mutex_unlock(&core_lock);
+ i2c_lock_adapter(adap);
+ list_add_tail(&client->detected, &adap->userspace_clients);
+ i2c_unlock_adapter(adap);
dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
info.type, info.addr);
@@ -583,9 +582,10 @@ i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
/* Make sure the device was added through sysfs */
res = -ENOENT;
- mutex_lock(&core_lock);
- list_for_each_entry_safe(client, next, &userspace_devices, detected) {
- if (client->addr == addr && client->adapter == adap) {
+ i2c_lock_adapter(adap);
+ list_for_each_entry_safe(client, next, &adap->userspace_clients,
+ detected) {
+ if (client->addr == addr) {
dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
"delete_device", client->name, client->addr);
@@ -595,7 +595,7 @@ i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
break;
}
}
- mutex_unlock(&core_lock);
+ i2c_unlock_adapter(adap);
if (res < 0)
dev_err(dev, "%s: Can't find device in list\n",
@@ -677,6 +677,7 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
}
rt_mutex_init(&adap->bus_lock);
+ INIT_LIST_HEAD(&adap->userspace_clients);
/* Set default timeout to 1 second if not already set */
if (adap->timeout == 0)
@@ -879,14 +880,15 @@ int i2c_del_adapter(struct i2c_adapter *adap)
return res;
/* Remove devices instantiated from sysfs */
- list_for_each_entry_safe(client, next, &userspace_devices, detected) {
- if (client->adapter == adap) {
- dev_dbg(&adap->dev, "Removing %s at 0x%x\n",
- client->name, client->addr);
- list_del(&client->detected);
- i2c_unregister_device(client);
- }
+ i2c_lock_adapter(adap);
+ list_for_each_entry_safe(client, next, &adap->userspace_clients,
+ detected) {
+ dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
+ client->addr);
+ list_del(&client->detected);
+ i2c_unregister_device(client);
}
+ i2c_unlock_adapter(adap);
/* Detach any active clients. This can't fail, thus we do not
checking the returned value. */
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 0a5da639b327..6ed1d59bfb1e 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -355,6 +355,8 @@ struct i2c_adapter {
int nr;
char name[48];
struct completion dev_released;
+
+ struct list_head userspace_clients;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)