path: root/include/hw/i2c/i2c.h
diff options
authorCorey Minyard <cminyard@mvista.com>2017-01-09 11:40:20 +0000
committerPeter Maydell <peter.maydell@linaro.org>2017-01-09 11:40:20 +0000
commitd307c28ca9dba7a0677035c9244198b05164c873 (patch)
treeee942307fac668f7a2d531bf6b86e6db025cdfd0 /include/hw/i2c/i2c.h
parentffe22bf51065dd33022cf91f77a821d1f11c250d (diff)
i2c: Allow I2C devices to NAK start events
Add a return value to the event handler. Some I2C devices will NAK if they have no data, so allow them to do this. This required the following changes: Go through all the event handlers and change them to return int and return 0. Modify i2c_start_transfer to terminate the transaction on a NAK. Modify smbus handing to not assert if a NAK occurs on a second operation, and terminate the transaction and return -1 instead. Add some information on semantics to I2CSlaveClass. Signed-off-by: Corey Minyard <cminyard@mvista.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'include/hw/i2c/i2c.h')
1 files changed, 12 insertions, 4 deletions
diff --git a/include/hw/i2c/i2c.h b/include/hw/i2c/i2c.h
index c4085aa366..2ce611d4c8 100644
--- a/include/hw/i2c/i2c.h
+++ b/include/hw/i2c/i2c.h
@@ -32,14 +32,22 @@ typedef struct I2CSlaveClass
/* Callbacks provided by the device. */
int (*init)(I2CSlave *dev);
- /* Master to slave. */
+ /* Master to slave. Returns non-zero for a NAK, 0 for success. */
int (*send)(I2CSlave *s, uint8_t data);
- /* Slave to master. */
+ /*
+ * Slave to master. This cannot fail, the device should always
+ * return something here. Negative values probably result in 0xff
+ * and a possible log from the driver, and shouldn't be used.
+ */
int (*recv)(I2CSlave *s);
- /* Notify the slave of a bus state change. */
- void (*event)(I2CSlave *s, enum i2c_event event);
+ /*
+ * Notify the slave of a bus state change. For start event,
+ * returns non-zero to NAK an operation. For other events the
+ * return code is not used and should be zero.
+ */
+ int (*event)(I2CSlave *s, enum i2c_event event);
} I2CSlaveClass;
struct I2CSlave