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Diffstat (limited to 'drivers/char/i2c.h')
| -rw-r--r-- | drivers/char/i2c.h | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/drivers/char/i2c.h b/drivers/char/i2c.h new file mode 100644 index 000000000..66aef224c --- /dev/null +++ b/drivers/char/i2c.h @@ -0,0 +1,166 @@ +#ifndef I2C_H +#define I2C_H + +/* + * linux i2c interface. Works a little bit like the scsi subsystem. + * There are: + * + * i2c the basic control module (like scsi_mod) + * bus driver a driver with a i2c bus (hostadapter driver) + * chip driver a driver for a chip connected + * to a i2c bus (cdrom/hd driver) + * + * A device will be attached to one bus and one chip driver. Every chip + * driver gets a unique ID. + * + * A chip driver can provide a ioctl-like callback for the + * communication with other parts of the kernel (not every i2c chip is + * useful without other devices, a TV card tuner for example). + * + * "i2c internal" parts of the structs: only the i2c module is allowed to + * write to them, for others they are read-only. + * + */ + +#define I2C_BUS_MAX 4 /* max # of bus drivers */ +#define I2C_DRIVER_MAX 8 /* max # of chip drivers */ +#define I2C_DEVICE_MAX 8 /* max # if devices per bus/driver */ + +struct i2c_bus; +struct i2c_driver; +struct i2c_device; + +#define I2C_DRIVERID_MSP3400 1 +#define I2C_DRIVERID_TUNER 2 +#define I2C_DRIVERID_VIDEOTEXT 3 + +#define I2C_BUSID_BT848 1 /* I2C bus on a BT848 */ + +/* + * struct for a driver for a i2c chip (tuner, soundprocessor, + * videotext, ... ). + * + * a driver will register within the i2c module. The i2c module will + * callback the driver (i2c_attach) for every device it finds on a i2c + * bus at the specified address. If the driver decides to "accept" + * the, device, it must return a struct i2c_device, and NULL + * otherwise. + * + * i2c_detach = i2c_attach ** -1 + * + * i2c_command will be used to pass commands to the driver in a + * ioctl-line manner. + * + */ + +struct i2c_driver +{ + char name[32]; /* some useful label */ + int id; /* device type ID */ + unsigned char addr_l, addr_h; /* address range of the chip */ + + int (*attach)(struct i2c_device *device); + int (*detach)(struct i2c_device *device); + int (*command)(struct i2c_device *device,unsigned int cmd, void *arg); + + /* i2c internal */ + struct i2c_device *devices[I2C_DEVICE_MAX]; + int devcount; +}; + + +/* + * this holds the informations about a i2c bus available in the system. + * + * a chip with a i2c bus interface (like bt848) registers the bus within + * the i2c module. This struct provides functions to access the i2c bus. + * + * One must hold the spinlock to access the i2c bus (XXX: is the irqsave + * required? Maybe better use a semaphore?). + * [-AC-] having a spinlock_irqsave is only needed if we have drivers wishing + * to bang their i2c bus from an interrupt. + * + * attach/detach_inform is a callback to inform the bus driver about + * attached chip drivers. + * + */ + +/* needed: unsigned long flags */ + +#define LOCK_I2C_BUS(bus) spin_lock_irqsave(&(bus->bus_lock),flags); +#define UNLOCK_I2C_BUS(bus) spin_unlock_irqrestore(&(bus->bus_lock),flags); + +struct i2c_bus +{ + char name[32]; /* some useful label */ + int id; + void *data; /* free for use by the bus driver */ + + spinlock_t bus_lock; + + /* attach/detach inform callbacks */ + void (*attach_inform)(struct i2c_bus *bus, int id); + void (*detach_inform)(struct i2c_bus *bus, int id); + + /* Software I2C */ + void (*i2c_setlines)(struct i2c_bus *bus, int ctrl, int data); + int (*i2c_getdataline)(struct i2c_bus *bus); + + /* Hardware I2C */ + int (*i2c_read)(struct i2c_bus *bus, unsigned char addr); + int (*i2c_write)(struct i2c_bus *bus, unsigned char addr, + unsigned char b1, unsigned char b2, int both); + + /* internal data for i2c module */ + struct i2c_device *devices[I2C_DEVICE_MAX]; + int devcount; +}; + + +/* + * This holds per-device data for a i2c device + */ + +struct i2c_device +{ + char name[32]; /* some useful label */ + void *data; /* free for use by the chip driver */ + unsigned char addr; /* chip addr */ + + /* i2c internal */ + struct i2c_bus *bus; + struct i2c_driver *driver; +}; + + +/* ------------------------------------------------------------------- */ +/* i2c module functions */ + +/* register/unregister a i2c bus */ +int i2c_register_bus(struct i2c_bus *bus); +int i2c_unregister_bus(struct i2c_bus *bus); + +/* register/unregister a chip driver */ +int i2c_register_driver(struct i2c_driver *driver); +int i2c_unregister_driver(struct i2c_driver *driver); + +/* send a command to a chip using the ioctl-like callback interface */ +int i2c_control_device(struct i2c_bus *bus, int id, + unsigned int cmd, void *arg); + +/* i2c bus access functions */ +void i2c_start(struct i2c_bus *bus); +void i2c_stop(struct i2c_bus *bus); +void i2c_one(struct i2c_bus *bus); +void i2c_zero(struct i2c_bus *bus); +int i2c_ack(struct i2c_bus *bus); + +int i2c_sendbyte(struct i2c_bus *bus,unsigned char data,int wait_for_ack); +unsigned char i2c_readbyte(struct i2c_bus *bus,int last); + +/* i2c (maybe) hardware functions */ +int i2c_read(struct i2c_bus *bus, unsigned char addr); +int i2c_write(struct i2c_bus *bus, unsigned char addr, + unsigned char b1, unsigned char b2, int both); + +#endif /* I2C_H */ |