From 4b1acc43331d6c716c331a61477660dc20c8b59c Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Tue, 18 Nov 2014 17:04:53 +0100 Subject: [PATCH] i2c: core changes for slave support Finally(!), make Linux support being an I2C slave. Most of the existing infrastructure is reused. We mainly add i2c_slave_register/unregister() calls which tells i2c bus drivers to activate the slave mode. Then, they also get a callback to report slave events to. Signed-off-by: Wolfram Sang Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-core.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/i2c.h | 29 +++++++++++++++++++++++++++++ 2 files changed, 78 insertions(+) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index 3105bd2..c09d06b 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -24,6 +24,7 @@ (c) 2013 Wolfram Sang I2C ACPI code Copyright (C) 2014 Intel Corp Author: Lan Tianyu + I2C slave support (c) 2014 by Wolfram Sang */ #include @@ -2911,6 +2912,54 @@ 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; + + i2c_lock_adapter(client->adapter); + ret = client->adapter->algo->reg_slave(client); + i2c_unlock_adapter(client->adapter); + + 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; + + i2c_lock_adapter(client->adapter); + ret = client->adapter->algo->unreg_slave(client); + i2c_unlock_adapter(client->adapter); + + if (ret == 0) + client->slave_cb = NULL; + + return ret; +} +EXPORT_SYMBOL_GPL(i2c_slave_unregister); + MODULE_AUTHOR("Simon G. Vogl "); MODULE_DESCRIPTION("I2C-Bus main module"); MODULE_LICENSE("GPL"); diff --git a/include/linux/i2c.h b/include/linux/i2c.h index b556e0a..a720d99 100644 --- a/include/linux/i2c.h +++ b/include/linux/i2c.h @@ -46,6 +46,8 @@ struct i2c_client; struct i2c_driver; union i2c_smbus_data; struct i2c_board_info; +enum i2c_slave_event; +typedef int (*i2c_slave_cb_t)(struct i2c_client *, enum i2c_slave_event, u8 *); struct module; @@ -209,6 +211,8 @@ struct i2c_driver { * @irq: indicates the IRQ generated by this device (if any) * @detected: member of an i2c_driver.clients list or i2c-core's * userspace_devices list + * @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter + * calls it to pass on slave events to the slave driver. * * An i2c_client identifies a single device (i.e. chip) connected to an * i2c bus. The behaviour exposed to Linux is defined by the driver @@ -224,6 +228,7 @@ 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) @@ -246,6 +251,25 @@ static inline void i2c_set_clientdata(struct i2c_client *dev, void *data) dev_set_drvdata(&dev->dev, data); } +/* 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, +}; + +extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb); +extern int i2c_slave_unregister(struct i2c_client *client); + +static inline int i2c_slave_event(struct i2c_client *client, + enum i2c_slave_event event, u8 *val) +{ + return client->slave_cb(client, event, val); +} + /** * struct i2c_board_info - template for device creation * @type: chip type, to initialize i2c_client.name @@ -352,6 +376,8 @@ i2c_register_board_info(int busnum, struct i2c_board_info const *info, * into I2C transfers instead. * @functionality: Return the flags that this algorithm/adapter pair supports * from the I2C_FUNC_* flags. + * @reg_slave: Register given client to I2C slave mode of this adapter + * @unreg_slave: Unregister given client from I2C slave mode of this adapter * * The following structs are for those who like to implement new bus drivers: * i2c_algorithm is the interface to a class of hardware solutions which can @@ -377,6 +403,9 @@ 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); }; /** -- 2.7.4