[RFC PATCH v2 2/7] i2c: core: use I2C locking behaviour also for SMBUS

Wolfram Sang
2019-03-02T13:47:30Z

If I2C transfers are executed in atomic contexts, trylock is used
instead of lock. This behaviour was missing for SMBUS, although a lot of
transfers are of SMBUS type, either emulated or direct. So, factor out
the locking routine into a helper and use it for I2C and SMBUS.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Peter Rosin <peda@axentia.se>
Acked-by: Tony Lindgren <tony@atomide.com>
---
drivers/i2c/i2c-core-base.c | 11 +++--------
drivers/i2c/i2c-core-smbus.c | 7 ++++++-
drivers/i2c/i2c-core.h | 12 ++++++++++++
3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index cb6c5cb0df0b..004f8a3b6365 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1946,14 +1946,9 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
* one (discarding status on the second message) or errno
* (discarding status on the first one).
*/
- if (in_atomic() || irqs_disabled()) {
- ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT);
- if (!ret)
- /* I2C activity is ongoing. */
- return -EAGAIN;
- } else {
- i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
- }
+ ret = __i2c_lock_bus_helper(adap);
+ if (ret)
+ return ret;

ret = __i2c_transfer(adap, msgs, num);
i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index 132119112596..357e083e8f45 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -20,6 +20,8 @@
#include <linux/i2c-smbus.h>
#include <linux/slab.h>

+#include "i2c-core.h"
+
#define CREATE_TRACE_POINTS
#include <trace/events/smbus.h>

@@ -530,7 +532,10 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
{
s32 res;

- i2c_lock_bus(adapter, I2C_LOCK_SEGMENT);
+ res = __i2c_lock_bus_helper(adapter);
+ if (res)
+ return res;
+
res = __i2c_smbus_xfer(adapter, addr, flags, read_write,
command, protocol, data);
i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT);
diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h
index 37576f50fe20..6e98aa811980 100644
--- a/drivers/i2c/i2c-core.h
+++ b/drivers/i2c/i2c-core.h
@@ -29,6 +29,18 @@ extern int __i2c_first_dynamic_bus_num;

int i2c_check_7bit_addr_validity_strict(unsigned short addr);

+static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap)
+{
+ int ret = 0;
+
+ if (in_atomic() || irqs_disabled())
+ ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT) ? 0 : -EAGAIN;
+ else
+ i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
+
+ return ret;
+}
+
#ifdef CONFIG_ACPI
const struct acpi_device_id *
i2c_acpi_match_device(const struct acpi_device_id *matches,
--
2.11.0