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i2c: core: helper function to detect slave mode 

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@synopsys.com>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Luis Oliveira 2017-01-26 17:45:32 +00:00 committed by Wolfram Sang
parent 50b918c5a6
commit cefae80249
2 changed files with 34 additions and 0 deletions
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33
drivers/i2c/i2c-core.c
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@ -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", &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@tk.uni-linz.ac.at>");

1
include/linux/i2c.h
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@ -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)