i3c: fix module_i3c_i2c_driver() with I3C=n

[ Upstream commit 5523a46 ]

When CONFIG_I3C is disabled and the i3c_i2c_driver_register() happens
to not be inlined, any driver calling it still references the i3c_driver
instance, which then causes a link failure:

x86_64-linux-ld: drivers/hwmon/lm75.o: in function `lm75_i3c_reg_read':
lm75.c:(.text+0xc61): undefined reference to `i3cdev_to_dev'
x86_64-linux-ld: lm75.c:(.text+0xd25): undefined reference to `i3c_device_do_priv_xfers'
x86_64-linux-ld: lm75.c:(.text+0xdd8): undefined reference to `i3c_device_do_priv_xfers'

This issue was part of the original i3c code, but only now caused problems
when i3c support got added to lm75.

Change the 'inline' annotations in the header to '__always_inline' to
ensure that the dead-code-elimination pass in the compiler can optimize
it out as intended.

Fixes: 6071d10 ("hwmon: (lm75) add I3C support for P3T1755")
Fixes: 3a379bb ("i3c: Add core I3C infrastructure")
Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Randy Dunlap <[email protected]>
Tested-by: Randy Dunlap <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]>
Reviewed-by: Frank Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexandre Belloni <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

Author: arndb

include/linux/i3c/device.h

@@ -245,7 +245,7 @@ void i3c_driver_unregister(struct i3c_driver *drv);
  *
  * Return: 0 if both registrations succeeds, a negative error code otherwise.
  */
-static inline int i3c_i2c_driver_register(struct i3c_driver *i3cdrv,
+static __always_inline int i3c_i2c_driver_register(struct i3c_driver *i3cdrv,
 					  struct i2c_driver *i2cdrv)
 {
 	int ret;
@@ -270,7 +270,7 @@ static inline int i3c_i2c_driver_register(struct i3c_driver *i3cdrv,
  * Note that when CONFIG_I3C is not enabled, this function only unregisters the
  * @i2cdrv.
  */
-static inline void i3c_i2c_driver_unregister(struct i3c_driver *i3cdrv,
+static __always_inline void i3c_i2c_driver_unregister(struct i3c_driver *i3cdrv,
 					     struct i2c_driver *i2cdrv)
 {
 	if (IS_ENABLED(CONFIG_I3C))