This function has the purpose of mode detection by checking the
device nodes for a reg matching with the I2C_OWN_SLAVE_ADDREESS flag.
Currently only checks using OF functions (ACPI slave not supported yet).
Signed-off-by: Luis Oliveira <lolivei@xxxxxxxxxxxx>
Suggested-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
---
Changes V3->V4: (@Wolfram)
- Rename of the function
- Reword of the function description
drivers/i2c/i2c-core.c | 33 +++++++++++++++++++++++++++++++++
include/linux/i2c.h | 1 +
2 files changed, 34 insertions(+)
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 583e95042a21..408de741fec5 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -3690,6 +3690,39 @@ int i2c_slave_unregister(struct i2c_client *client)
return ret;
}
EXPORT_SYMBOL_GPL(i2c_slave_unregister);
+
+/**
+ * i2c_detect_slave_mode - detect operation mode
+ * @dev: The device owning the bus
+ *
+ * This checks the device nodes for an I2C slave by checking the address
+ * used in the reg property. If the address match the I2C_OWN_SLAVE_ADDRESS
+ * flag this means the device is configured to act as a I2C slave and it will
+ * be listening at that address.
+ *
+ * Returns true if an I2C own slave address is detected, otherwise returns
+ * false.
+ */
+bool i2c_detect_slave_mode(struct device *dev)
+{
+ if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
+ struct device_node *child;
+ u32 reg;
+
+ for_each_child_of_node(dev->of_node, child) {
+ of_property_read_u32(child, "reg", ®);
+ if (reg & I2C_OWN_SLAVE_ADDRESS) {
+ of_node_put(child);
+ return true;
+ }
+ }
+ } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
+ dev_dbg(dev, "ACPI slave is not supported yet\n");
+ }
+ return false;
+}
+EXPORT_SYMBOL_GPL(i2c_detect_slave_mode);
+
#endif
MODULE_AUTHOR("Simon G. Vogl <simon@xxxxxxxxxxxxxxxxx>");
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 4b45ec46161f..f0ba4bac7452 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -282,6 +282,7 @@ enum i2c_slave_event {
extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb);
extern int i2c_slave_unregister(struct i2c_client *client);
+extern bool i2c_detect_slave_mode(struct device *dev);
static inline int i2c_slave_event(struct i2c_client *client,
enum i2c_slave_event event, u8 *val)
--
2.11.0
--
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