[RFC 1/4] i2c: core changes for slave support

Wolfram Sang
2014-09-09T14:54:34Z

From: Wolfram Sang <wsa+renesas@sang-engineering.com>

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
drivers/i2c/i2c-core.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/i2c.h | 22 ++++++++++++++++++++++
2 files changed, 66 insertions(+)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 632057a44615..6713d438539b 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -27,6 +27,7 @@
OF support is copyright (c) 2008 Jochen Friedrich <jochen@scram.de>
(based on a previous patch from Jon Smirl <jonsmirl@gmail.com>) and
(c) 2013 Wolfram Sang <wsa@the-dreams.de>
+ I2C slave support (c) 2014 by Wolfram Sang <wsa@sang-engineering.com>
*/

#include <linux/module.h>
@@ -2536,6 +2537,49 @@ trace:
}
EXPORT_SYMBOL(i2c_smbus_xfer);

+int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
+{
+ int ret;
+
+ if (!client || !slave_cb)
+ return -EINVAL;
+
+ if (!(client->flags & I2C_CLIENT_TEN)) {
+ /* Enforce stricter address checking */
+ ret = i2c_check_addr_validity(client->addr);
+ if (ret)
+ return ret;
+ }
+
+ if (!client->adapter->algo->reg_slave)
+ return -EOPNOTSUPP;
+
+ client->slave_cb = slave_cb;
+
+ ret = client->adapter->algo->reg_slave(client);
+ if (ret)
+ client->slave_cb = NULL;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_slave_register);
+
+int i2c_slave_unregister(struct i2c_client *client)
+{
+ int ret;
+
+ if (!client->adapter->algo->unreg_slave)
+ return -EOPNOTSUPP;
+
+ ret = client->adapter->algo->unreg_slave(client);
+
+ if (ret == 0)
+ client->slave_cb = NULL;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_slave_unregister);
+
MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C-Bus main module");
MODULE_LICENSE("GPL");
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index a95efeb53a8b..11d4edb1ab3e 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -121,6 +121,24 @@ extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
const u8 *values);
#endif /* I2C */

+/* I2C slave support */
+
+enum i2c_slave_event {
+ I2C_SLAVE_REQ_READ_START,
+ I2C_SLAVE_REQ_READ_END,
+ I2C_SLAVE_REQ_WRITE_START,
+ I2C_SLAVE_REQ_WRITE_END,
+ I2C_SLAVE_STOP,
+};
+
+typedef int (*i2c_slave_cb_t)(struct i2c_client *, enum i2c_slave_event, u8 *);
+
+extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb);
+extern int i2c_slave_unregister(struct i2c_client *client);
+
+#define i2c_slave_event(__client, __event, __value) \
+ __client->slave_cb(__client, __event, __value)
+
/**
* struct i2c_driver - represent an I2C device driver
* @class: What kind of i2c device we instantiate (for detect)
@@ -224,6 +242,7 @@ struct i2c_client {
struct device dev; /* the device structure */
int irq; /* irq issued by device */
struct list_head detected;
+ i2c_slave_cb_t slave_cb; /* callback for slave mode */
};
#define to_i2c_client(d) container_of(d, struct i2c_client, dev)

@@ -377,6 +396,9 @@ struct i2c_algorithm {

/* To determine what the adapter supports */
u32 (*functionality) (struct i2c_adapter *);
+
+ int (*reg_slave)(struct i2c_client *client);
+ int (*unreg_slave)(struct i2c_client *client);
};

/**
--
2.0.0