Hi Greg,
Here is an update to my 2.4 to 2.6 i2c client porting guide. The changes
were inspired by the feedback I got with the drivers that have been
ported so far.
Please apply,
Thanks.
--- linux-2.6.5-rc2/Documentation/i2c/porting-clients.orig Fri Jan 16 20:10:15 2004
+++ linux-2.6.5-rc2/Documentation/i2c/porting-clients Tue Mar 30 20:14:41 2004
@@ -1,4 +1,4 @@
-Revision 3, 2003-10-04
+Revision 4, 2004-03-30
Jean Delvare <khali at linux-fr.org>
Greg KH <greg at kroah.com>
@@ -24,9 +24,10 @@
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/i2c-sensor.h>
- #include <linux/i2c-vid.h> /* if you need VRM support */
- #include <asm/io.h> /* if you have I/O operations */
- Some extra headers may be required for a given driver.
+ #include <linux/i2c-vid.h> /* if you need VRM support */
+ #include <asm/io.h> /* if you have I/O operations */
+ Please respect this inclusion order. Some extra headers may be
+ required for a given driver (e.g. "lm75.h").
* [Addresses] SENSORS_I2C_END becomes I2C_CLIENT_END, SENSORS_ISA_END
becomes I2C_CLIENT_ISA_END.
@@ -37,9 +38,9 @@
names for sysfs files (see the Sysctl section below).
* [Function prototypes] The detect functions loses its flags
- parameter. Sysctl (e.g. lm75_temp) and miscellaneous (e.g.
- swap_bytes) functions are off the list of prototypes. This
- usually leaves five prototypes:
+ parameter. Sysctl (e.g. lm75_temp) and miscellaneous functions
+ are off the list of prototypes. This usually leaves five
+ prototypes:
static int lm75_attach_adapter(struct i2c_adapter *adapter);
static int lm75_detect(struct i2c_adapter *adapter, int address,
int kind);
@@ -70,13 +71,14 @@
* [Detect] As mentioned earlier, the flags parameter is gone.
The type_name and client_name strings are replaced by a single
name string, which will be filled with a lowercase, short string
- (typically the driver name, e.g. "lm75"). The errorN labels are
- reduced to the number needed. If that number is 2 (i2c-only
- drivers), it is advised that the labels are named exit and
- exit_free. For i2c+isa drivers, labels should be named ERROR0,
- ERROR1 and ERROR2. Don't forget to properly set err before
- jumping to error labels. By the way, labels should be
- left-aligned.
+ (typically the driver name, e.g. "lm75").
+ In i2c-only drivers, drop the i2c_is_isa_adapter check, it's
+ useless.
+ The errorN labels are reduced to the number needed. If that number
+ is 2 (i2c-only drivers), it is advised that the labels are named
+ exit and exit_free. For i2c+isa drivers, labels should be named
+ ERROR0, ERROR1 and ERROR2. Don't forget to properly set err before
+ jumping to error labels. By the way, labels should be left-aligned.
Use memset to fill the client and data area with 0x00.
Use i2c_set_clientdata to set the client data (as opposed to
a direct access to client->data).
@@ -85,6 +87,11 @@
device_create_file. Move the driver initialization before any
sysfs file creation.
+* [Init] Limits must not be set by the driver (can be done later in
+ user-space). Chip should not be reset default (although a module
+ parameter may be used to force is), and initialization should be
+ limited to the strictly necessary steps.
+
* [Detach] Get rid of data, remove the call to
i2c_deregister_entry.
@@ -92,7 +99,8 @@
i2c_get_clientdata(client) instead.
* [Interface] Init function should not print anything. Make sure
- there is a MODULE_LICENSE() line.
+ there is a MODULE_LICENSE() line, at the bottom of the file
+ (after MODULE_AUTHOR() and MODULE_DESCRIPTION(), in this order).
Coding policy:
@@ -102,8 +110,7 @@
can. Calls to printk/pr_debug for debugging purposes are replaced
by calls to dev_dbg. Here is an example on how to call it (taken
from lm75_detect):
- dev_dbg(&adapter->dev,
- "lm75_detect called for an ISA bus adapter?!?\n");
+ dev_dbg(&client->dev, "Starting lm75 update\n");
Replace other printk calls with the dev_info, dev_err or dev_warn
function, as appropriate.
@@ -119,3 +126,8 @@
* [Layout] Avoid extra empty lines between comments and what they
comment. Respect the coding style (see Documentation/CodingStyle),
in particular when it comes to placing curly braces.
+
+* [Comments] Make sure that no comment refers to a file that isn't
+ part of the Linux source tree (typically doc/chips/<chip name>),
+ and that remaining comments still match the code. Merging comment
+ lines when possible is encouraged.
--
Jean Delvare
http://www.ensicaen.ismra.fr/~delvare/
