include/linux/i2c.h

   1 #ifndef I2C_H
   2 #define I2C_H
   3
   4 /*
   5  * linux i2c interface.  Works a little bit like the scsi subsystem.
   6  * There are:
   7  *
   8  *     i2c          the basic control module        (like scsi_mod)
   9  *     bus driver   a driver with a i2c bus         (hostadapter driver)
  10  *     chip driver  a driver for a chip connected
  11  *                  to a i2c bus                    (cdrom/hd driver)
  12  *
  13  * A device will be attached to one bus and one chip driver.  Every chip
  14  * driver gets a unique ID.
  15  *
  16  * A chip driver can provide a ioctl-like callback for the
  17  * communication with other parts of the kernel (not every i2c chip is
  18  * useful without other devices, a TV card tuner for example).
  19  *
  20  * "i2c internal" parts of the structs: only the i2c module is allowed to
  21  * write to them, for others they are read-only.
  22  *
  23  */
  24
  25 #include <linux/version.h>
  26
  27 #define I2C_BUS_MAX       4    /* max # of bus drivers  */
  28 #define I2C_DRIVER_MAX    8    /* max # of chip drivers */
  29 #define I2C_DEVICE_MAX    8    /* max # if devices per bus/driver */
  30
  31 struct i2c_bus;
  32 struct i2c_driver;
  33 struct i2c_device;
  34
  35 #define I2C_DRIVERID_MSP3400     1
  36 #define I2C_DRIVERID_TUNER       2
  37 #define I2C_DRIVERID_VIDEOTEXT   3
  38
  39 #define I2C_BUSID_BT848         1       /* I2C bus on a BT848 */
  40 #define I2C_BUSID_PARPORT       2       /* Bit banging on a parallel port */
  41
  42 /*
  43  * struct for a driver for a i2c chip (tuner, soundprocessor,
  44  * videotext, ... ).
  45  *
  46  * a driver will register within the i2c module.  The i2c module will
  47  * callback the driver (i2c_attach) for every device it finds on a i2c
  48  * bus at the specified address.  If the driver decides to "accept"
  49  * the, device, it must return a struct i2c_device, and NULL
  50  * otherwise.
  51  *
  52  * i2c_detach = i2c_attach ** -1
  53  *
  54  * i2c_command will be used to pass commands to the driver in a
  55  * ioctl-line manner.
  56  *
  57  */
  58
  59 struct i2c_driver
  60 {
  61     char           name[32];         /* some useful label         */
  62     int            id;               /* device type ID            */
  63     unsigned char  addr_l, addr_h;   /* address range of the chip */
  64
  65     int (*attach)(struct i2c_device *device);
  66     int (*detach)(struct i2c_device *device);
  67     int (*command)(struct i2c_device *device,unsigned int cmd, void *arg);
  68
  69     /* i2c internal */
  70     struct i2c_device   *devices[I2C_DEVICE_MAX];
  71     int                 devcount;
  72 };
  73
  74
  75 /*
  76  * this holds the informations about a i2c bus available in the system.
  77  *
  78  * a chip with a i2c bus interface (like bt848) registers the bus within
  79  * the i2c module. This struct provides functions to access the i2c bus.
  80  *
  81  * One must hold the spinlock to access the i2c bus (XXX: is the irqsave
  82  * required? Maybe better use a semaphore?).
  83  * [-AC-] having a spinlock_irqsave is only needed if we have drivers wishing
  84  *        to bang their i2c bus from an interrupt.
  85  *
  86  * attach/detach_inform is a callback to inform the bus driver about
  87  * attached chip drivers.
  88  *
  89  */
  90
  91 /* needed: unsigned long flags */
  92
  93 #if LINUX_VERSION_CODE >= 0x020100
  94 # if 0
  95 #  define LOCK_FLAGS unsigned long flags;
  96 #  define LOCK_I2C_BUS(bus)    spin_lock_irqsave(&(bus->bus_lock),flags);
  97 #  define UNLOCK_I2C_BUS(bus)  spin_unlock_irqrestore(&(bus->bus_lock),flags);
  98 # else
  99 #  define LOCK_FLAGS
 100 #  define LOCK_I2C_BUS(bus)    spin_lock(&(bus->bus_lock));
 101 #  define UNLOCK_I2C_BUS(bus)  spin_unlock(&(bus->bus_lock));
 102 # endif
 103 #else
 104 # define LOCK_FLAGS unsigned long flags;
 105 # define LOCK_I2C_BUS(bus)    { save_flags(flags); cli(); }
 106 # define UNLOCK_I2C_BUS(bus)  { restore_flags(flags);     }
 107 #endif
 108
 109 struct i2c_bus
 110 {
 111         char  name[32];         /* some useful label */
 112         int   id;
 113         void  *data;            /* free for use by the bus driver */
 114
 115 #if LINUX_VERSION_CODE >= 0x020100
 116         spinlock_t bus_lock;
 117 #endif
 118
 119         /* attach/detach inform callbacks */
 120         void    (*attach_inform)(struct i2c_bus *bus, int id);
 121         void    (*detach_inform)(struct i2c_bus *bus, int id);
 122
 123         /* Software I2C */
 124         void    (*i2c_setlines)(struct i2c_bus *bus, int ctrl, int data);
 125         int     (*i2c_getdataline)(struct i2c_bus *bus);
 126
 127         /* Hardware I2C */
 128         int     (*i2c_read)(struct i2c_bus *bus, unsigned char addr);
 129         int     (*i2c_write)(struct i2c_bus *bus, unsigned char addr,
 130                          unsigned char b1, unsigned char b2, int both);
 131
 132         /* internal data for i2c module */
 133         struct i2c_device   *devices[I2C_DEVICE_MAX];
 134         int                 devcount;
 135 };
 136
 137
 138 /*
 139  *      This holds per-device data for a i2c device
 140  */
 141
 142 struct i2c_device
 143 {
 144         char           name[32];         /* some useful label */
 145         void           *data;            /* free for use by the chip driver */
 146         unsigned char  addr;             /* chip addr */
 147
 148         /* i2c internal */
 149         struct i2c_bus     *bus;
 150         struct i2c_driver  *driver;
 151 };
 152
 153
 154 /* ------------------------------------------------------------------- */
 155 /* i2c module functions                                                */
 156
 157 /* register/unregister a i2c bus */
 158 int i2c_register_bus(struct i2c_bus *bus);
 159 int i2c_unregister_bus(struct i2c_bus *bus);
 160
 161 /* register/unregister a chip driver */
 162 int i2c_register_driver(struct i2c_driver *driver);
 163 int i2c_unregister_driver(struct i2c_driver *driver);
 164
 165 /* send a command to a chip using the ioctl-like callback interface */
 166 int i2c_control_device(struct i2c_bus *bus, int id,
 167                        unsigned int cmd, void *arg);
 168
 169 /* i2c bus access functions */
 170 void    i2c_start(struct i2c_bus *bus);
 171 void    i2c_stop(struct i2c_bus *bus);
 172 void    i2c_one(struct i2c_bus *bus);
 173 void    i2c_zero(struct i2c_bus *bus);
 174 int     i2c_ack(struct i2c_bus *bus);
 175
 176 int     i2c_sendbyte(struct i2c_bus *bus,unsigned char data,int wait_for_ack);
 177 unsigned char i2c_readbyte(struct i2c_bus *bus,int last);
 178
 179 /* i2c (maybe) hardware functions */
 180 int     i2c_read(struct i2c_bus *bus, unsigned char addr);
 181 int     i2c_write(struct i2c_bus *bus, unsigned char addr,
 182                   unsigned char b1, unsigned char b2, int both);
 183
 184 int     i2c_init(void);
 185 #endif /* I2C_H */