Hi all,
For the 2.9.0 release of i2c and lm_sensors, a big work has been done to
address compatibility problems between 2.4 kernels and i2c/lm-sensors.
The compatibility was announced as restored, but unfortunately, there is
still a small difference in one structure defined in i2c.h, namely
i2c_adapter.
I have tried to do a patch to fix the latest issues, but I am not sure
it is correctly done.
In the kernel version of i2c.h, the client_count variable is present,
whereas it is not in the i2c one. I have simply added it, as well as the
code to increment/decrement it.
Then the complex part is about the semaphores:
In the kernel a semaphore called lock is used to only allow one i2c
transfer at once. In i2c, a semaphore is also used for the same job, but
called bus. The fix was easy, just renaming the variable.
But there is one more semaphore in i2c, called list, used to lock the
list of i2c clients. This one is not present in the kernel, as this
list was not locked in i2c 2.7.0 and previous versions. I supposed it
has been added due to some race conditions that have been observed, so I
choosed to use the same semaphore as for i2c transfer to lock the clients
list. It has the drawback to not allow an i2c transfer while
adding/removing a client or to not allow adding a new client during an
i2c transfer. I don't consider that as a problem, as adding/removing a
client does not happen so often. I have also checked that not i2c
transfers are asked between too lock of the list.
I haven't tested my patch (only tested it build correctly), because I am
not at home, so I can't change easily my 2.6 kernel to a 2.4 one.
Nevertheless, I would like for people with good knowledge of i2c-core.c
to tell me if the patch seems ok or not. Thanks.
Bye,
Aurelien
--
.''`. Aurelien Jarno | GPG: 1024D/F1BCDB73
: :' : Debian GNU/Linux developer | Electrical Engineer
`. `' aurel32 at debian.org | aurelien at aurel32.net
`- people.debian.org/~aurel32 | www.aurel32.net
-------------- next part --------------
Index: kernel/i2c-core.c
===================================================================
RCS file: /home/cvs/i2c/kernel/i2c-core.c,v
retrieving revision 1.106
diff -u -d -p -r1.106 i2c-core.c
--- kernel/i2c-core.c 22 Jan 2005 09:01:56 -0000 1.106
+++ kernel/i2c-core.c 8 Mar 2005 14:20:04 -0000
@@ -104,8 +104,7 @@ int i2c_add_adapter(struct i2c_adapter *
adapters[i] = adap;
/* init data types */
- init_MUTEX(&adap->bus);
- init_MUTEX(&adap->list);
+ init_MUTEX(&adap->lock);
/* inform drivers of new adapters */
for (j=0;j<I2C_DRIVER_MAX;j++)
@@ -311,9 +310,9 @@ int i2c_check_addr (struct i2c_adapter *
{
int rval;
- down(&adapter->list);
+ down(&adapter->lock);
rval = __i2c_check_addr(adapter, addr);
- up(&adapter->list);
+ up(&adapter->lock);
return rval;
}
@@ -326,7 +325,7 @@ int i2c_attach_client(struct i2c_client
if (i2c_check_addr(client->adapter,client->addr))
return -EBUSY;
- down(&adapter->list);
+ down(&adapter->lock);
for (i = 0; i < I2C_CLIENT_MAX; i++)
if (NULL == adapter->clients[i])
break;
@@ -334,11 +333,12 @@ int i2c_attach_client(struct i2c_client
printk(KERN_WARNING
" i2c-core.o: attach_client(%s) - enlarge I2C_CLIENT_MAX.\n",
client->name);
- up(&adapter->list);
+ up(&adapter->lock);
return -ENOMEM;
}
adapter->clients[i] = client;
- up(&adapter->list);
+ adapter->client_count++;
+ up(&adapter->lock);
if (adapter->client_register)
if (adapter->client_register(client))
@@ -371,7 +371,7 @@ int i2c_detach_client(struct i2c_client
return res;
}
- down(&adapter->list);
+ down(&adapter->lock);
for (i = 0; i < I2C_CLIENT_MAX; i++)
if (client == adapter->clients[i])
break;
@@ -379,11 +379,12 @@ int i2c_detach_client(struct i2c_client
printk(KERN_WARNING " i2c-core.o: unregister_client "
"[%s] not found\n",
client->name);
- up(&adapter->list);
+ up(&adapter->lock);
return -ENODEV;
}
adapter->clients[i] = NULL;
- up(&adapter->list);
+ adapter->client_count--;
+ up(&adapter->lock);
DEB(printk(KERN_DEBUG "i2c-core.o: client [%s] unregistered.\n",client->name));
return 0;
@@ -580,7 +581,7 @@ ssize_t i2cproc_bus_read(struct file * f
/* Order will hold the indexes of the clients
sorted by address */
order_nr=0;
- down(&adap->list);
+ down(&adap->lock);
for (j = 0; j < I2C_CLIENT_MAX; j++) {
if ((client = adap->clients[j]) &&
(client->driver->id != I2C_DRIVERID_I2CDEV)) {
@@ -603,7 +604,7 @@ ssize_t i2cproc_bus_read(struct file * f
client->name,
client->driver->name);
}
- up(&adap->list);
+ up(&adap->lock);
up(&core_lists);
len = len - file->f_pos;
@@ -681,9 +682,9 @@ int i2c_transfer(struct i2c_adapter * ad
DEB2(printk(KERN_DEBUG "i2c-core.o: master_xfer: %s with %d msgs.\n",
adap->name,num));
- down(&adap->bus);
+ down(&adap->lock);
ret = adap->algo->master_xfer(adap,msgs,num);
- up(&adap->bus);
+ up(&adap->lock);
return ret;
} else {
@@ -708,9 +709,9 @@ int i2c_master_send(struct i2c_client *c
DEB2(printk(KERN_DEBUG "i2c-core.o: master_send: writing %d bytes on %s.\n",
count,client->adapter->name));
- down(&adap->bus);
+ down(&adap->lock);
ret = adap->algo->master_xfer(adap,&msg,1);
- up(&adap->bus);
+ up(&adap->lock);
/* if everything went ok (i.e. 1 msg transmitted), return #bytes
* transmitted, else error code.
@@ -738,9 +739,9 @@ int i2c_master_recv(struct i2c_client *c
DEB2(printk(KERN_DEBUG "i2c-core.o: master_recv: reading %d bytes on %s.\n",
count,client->adapter->name));
- down(&adap->bus);
+ down(&adap->lock);
ret = adap->algo->master_xfer(adap,&msg,1);
- up(&adap->bus);
+ up(&adap->lock);
DEB2(printk(KERN_DEBUG "i2c-core.o: master_recv: return:%d (count:%d, addr:0x%02x)\n",
ret, count, client->addr));
@@ -1403,10 +1404,10 @@ s32 i2c_smbus_xfer(struct i2c_adapter *
}
if (adap->algo->smbus_xfer) {
- down(&adap->bus);
+ down(&adap->lock);
res = adap->algo->smbus_xfer(adap,addr,flags,read_write,
command,size,data);
- up(&adap->bus);
+ up(&adap->lock);
} else
res = i2c_smbus_xfer_emulated(adap,addr,flags,read_write,
command,size,data);
Index: kernel/i2c.h
===================================================================
RCS file: /home/cvs/i2c/kernel/i2c.h,v
retrieving revision 1.87
diff -u -d -p -r1.87 i2c.h
--- kernel/i2c.h 22 Jan 2005 09:04:13 -0000 1.87
+++ kernel/i2c.h 8 Mar 2005 14:20:05 -0000
@@ -237,11 +237,11 @@ struct i2c_adapter {
/* and can be set via the i2c_ioctl call */
/* data fields that are valid for all devices */
- struct semaphore bus;
- struct semaphore list;
+ struct semaphore lock;
unsigned int flags;/* flags specifying div. data */
struct i2c_client *clients[I2C_CLIENT_MAX];
+ int client_count;
int timeout;
int retries;
