i2c: core: Fix atomic xfer check for non-preempt config

Since commit aa49c908 ("i2c: core: Run atomic i2c xfer when
!preemptible"), the whole reboot/power off sequence on non-preempt kernels
is using atomic i2c xfer, as !preemptible() always results to 1.

During device_shutdown(), the i2c might be used a lot and not all busses
have implemented an atomic xfer handler. This results in a lot of
avoidable noise, like:

[   12.687169] No atomic I2C transfer handler for 'i2c-0'
[   12.692313] WARNING: CPU: 6 PID: 275 at drivers/i2c/i2c-core.h:40 i2c_smbus_xfer+0x100/0x118
...

Fix this by allowing non-atomic xfer when the interrupts are enabled, as
it was before.

Link: https://lore.kernel.org/r/20231222230106.73f030a5@yea
Link: https://lore.kernel.org/r/20240102150350.3180741-1-mwalle@kernel.org
Link: https://lore.kernel.org/linux-i2c/13271b9b-4132-46ef-abf8-2c311967bb46@mailbox.org/
Fixes: aa49c908 ("i2c: core: Run atomic i2c xfer when !preemptible")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>
Tested-by: Michael Walle <mwalle@kernel.org>
Tested-by: Tor Vic <torvic9@mailbox.org>
[wsa: removed a comment which needs more work, code is ok]
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/i2c-core.h

@@ -3,6 +3,7 @@
  * i2c-core.h - interfaces internal to the I2C framework
  */
 
+#include <linux/kconfig.h>
 #include <linux/rwsem.h>
 
 struct i2c_devinfo {
@@ -29,7 +30,8 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
  */
 static inline bool i2c_in_atomic_xfer_mode(void)
 {
-	return system_state > SYSTEM_RUNNING && !preemptible();
+	return system_state > SYSTEM_RUNNING &&
+	       (IS_ENABLED(CONFIG_PREEMPT_COUNT) ? !preemptible() : irqs_disabled());
 }
 
 static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap)