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 #define I2C_DRIVERID_VIDEODECODER        4
  39 #define I2C_DRIVERID_VIDEOENCODER        5
  40
  41 #define I2C_BUSID_BT848         1       /* I2C bus on a BT848 */
  42 #define I2C_BUSID_PARPORT       2       /* Bit banging on a parallel port */
  43 #define I2C_BUSID_BUZ           3
  44 #define I2C_BUSID_ZORAN         4
  45
  46 /*
  47  * struct for a driver for a i2c chip (tuner, soundprocessor,
  48  * videotext, ... ).
  49  *
  50  * a driver will register within the i2c module.  The i2c module will
  51  * callback the driver (i2c_attach) for every device it finds on a i2c
  52  * bus at the specified address.  If the driver decides to "accept"
  53  * the, device, it must return a struct i2c_device, and NULL
  54  * otherwise.
  55  *
  56  * i2c_detach = i2c_attach ** -1
  57  *
  58  * i2c_command will be used to pass commands to the driver in a
  59  * ioctl-line manner.
  60  *
  61  */
  62
  63 struct i2c_driver
  64 {
  65     char           name[32];         /* some useful label         */
  66     int            id;               /* device type ID            */
  67     unsigned char  addr_l, addr_h;   /* address range of the chip */
  68
  69     int (*attach)(struct i2c_device *device);
  70     int (*detach)(struct i2c_device *device);
  71     int (*command)(struct i2c_device *device,unsigned int cmd, void *arg);
  72
  73     /* i2c internal */
  74     struct i2c_device   *devices[I2C_DEVICE_MAX];
  75     int                 devcount;
  76 };
  77
  78
  79 /*
  80  * this holds the informations about a i2c bus available in the system.
  81  *
  82  * a chip with a i2c bus interface (like bt848) registers the bus within
  83  * the i2c module. This struct provides functions to access the i2c bus.
  84  *
  85  * One must hold the spinlock to access the i2c bus (XXX: is the irqsave
  86  * required? Maybe better use a semaphore?).
  87  * [-AC-] having a spinlock_irqsave is only needed if we have drivers wishing
  88  *        to bang their i2c bus from an interrupt.
  89  *
  90  * attach/detach_inform is a callback to inform the bus driver about
  91  * attached chip drivers.
  92  *
  93  */
  94
  95 /* needed: unsigned long flags */
  96
  97 #if LINUX_VERSION_CODE >= 0x020100
  98 # if 0
  99 #  define LOCK_FLAGS unsigned long flags;
 100 #  define LOCK_I2C_BUS(bus)    spin_lock_irqsave(&(bus->bus_lock),flags);
 101 #  define UNLOCK_I2C_BUS(bus)  spin_unlock_irqrestore(&(bus->bus_lock),flags);
 102 # else
 103 #  define LOCK_FLAGS
 104 #  define LOCK_I2C_BUS(bus)    spin_lock(&(bus->bus_lock));
 105 #  define UNLOCK_I2C_BUS(bus)  spin_unlock(&(bus->bus_lock));
 106 # endif
 107 #else
 108 # define LOCK_FLAGS unsigned long flags;
 109 # define LOCK_I2C_BUS(bus)    { save_flags(flags); cli(); }
 110 # define UNLOCK_I2C_BUS(bus)  { restore_flags(flags);     }
 111 #endif
 112
 113 struct i2c_bus
 114 {
 115         char  name[32];         /* some useful label */
 116         int   id;
 117         void  *data;            /* free for use by the bus driver */
 118
 119 #if LINUX_VERSION_CODE >= 0x020100
 120         spinlock_t bus_lock;
 121 #endif
 122
 123         /* attach/detach inform callbacks */
 124         void    (*attach_inform)(struct i2c_bus *bus, int id);
 125         void    (*detach_inform)(struct i2c_bus *bus, int id);
 126
 127         /* Software I2C */
 128         void    (*i2c_setlines)(struct i2c_bus *bus, int ctrl, int data);
 129         int     (*i2c_getdataline)(struct i2c_bus *bus);
 130
 131         /* Hardware I2C */
 132         int     (*i2c_read)(struct i2c_bus *bus, unsigned char addr);
 133         int     (*i2c_write)(struct i2c_bus *bus, unsigned char addr,
 134                          unsigned char b1, unsigned char b2, int both);
 135
 136         /* internal data for i2c module */
 137         struct i2c_device   *devices[I2C_DEVICE_MAX];
 138         int                 devcount;
 139 };
 140
 141
 142 /*
 143  *      This holds per-device data for a i2c device
 144  */
 145
 146 struct i2c_device
 147 {
 148         char           name[32];         /* some useful label */
 149         void           *data;            /* free for use by the chip driver */
 150         unsigned char  addr;             /* chip addr */
 151
 152         /* i2c internal */
 153         struct i2c_bus     *bus;
 154         struct i2c_driver  *driver;
 155 };
 156
 157
 158 /* ------------------------------------------------------------------- */
 159 /* i2c module functions                                                */
 160
 161 /* register/unregister a i2c bus */
 162 int i2c_register_bus(struct i2c_bus *bus);
 163 int i2c_unregister_bus(struct i2c_bus *bus);
 164
 165 /* register/unregister a chip driver */
 166 int i2c_register_driver(struct i2c_driver *driver);
 167 int i2c_unregister_driver(struct i2c_driver *driver);
 168
 169 /* send a command to a chip using the ioctl-like callback interface */
 170 int i2c_control_device(struct i2c_bus *bus, int id,
 171                        unsigned int cmd, void *arg);
 172
 173 /* i2c bus access functions */
 174 void    i2c_start(struct i2c_bus *bus);
 175 void    i2c_stop(struct i2c_bus *bus);
 176 void    i2c_one(struct i2c_bus *bus);
 177 void    i2c_zero(struct i2c_bus *bus);
 178 int     i2c_ack(struct i2c_bus *bus);
 179
 180 int     i2c_sendbyte(struct i2c_bus *bus,unsigned char data,int wait_for_ack);
 181 unsigned char i2c_readbyte(struct i2c_bus *bus,int last);
 182
 183 /* i2c (maybe) hardware functions */
 184 int     i2c_read(struct i2c_bus *bus, unsigned char addr);
 185 int     i2c_write(struct i2c_bus *bus, unsigned char addr,
 186                   unsigned char b1, unsigned char b2, int both);
 187
 188 int     i2c_init(void);
 189 #endif /* I2C_H */