include/hw/i2c/i2c.h

   1 #ifndef QEMU_I2C_H
   2 #define QEMU_I2C_H
   3
   4 #include "hw/qdev-core.h"
   5 #include "qom/object.h"
   6
   7 /* The QEMU I2C implementation only supports simple transfers that complete
   8    immediately.  It does not support slave devices that need to be able to
   9    defer their response (eg. CPU slave interfaces where the data is supplied
  10    by the device driver in response to an interrupt).  */
  11
  12 enum i2c_event {
  13     I2C_START_RECV,
  14     I2C_START_SEND,
  15     I2C_FINISH,
  16     I2C_NACK /* Masker NACKed a receive byte.  */
  17 };
  18
  19 typedef struct I2CNodeList I2CNodeList;
  20
  21 #define TYPE_I2C_SLAVE "i2c-slave"
  22 OBJECT_DECLARE_TYPE(I2CSlave, I2CSlaveClass,
  23                     I2C_SLAVE)
  24
  25 struct I2CSlaveClass {
  26     DeviceClass parent_class;
  27
  28     /* Master to slave. Returns non-zero for a NAK, 0 for success. */
  29     int (*send)(I2CSlave *s, uint8_t data);
  30
  31     /*
  32      * Slave to master.  This cannot fail, the device should always
  33      * return something here.
  34      */
  35     uint8_t (*recv)(I2CSlave *s);
  36
  37     /*
  38      * Notify the slave of a bus state change.  For start event,
  39      * returns non-zero to NAK an operation.  For other events the
  40      * return code is not used and should be zero.
  41      */
  42     int (*event)(I2CSlave *s, enum i2c_event event);
  43
  44     /*
  45      * Check if this device matches the address provided.  Returns bool of
  46      * true if it matches (or broadcast), and updates the device list, false
  47      * otherwise.
  48      *
  49      * If broadcast is true, match should add the device and return true.
  50      */
  51     bool (*match_and_add)(I2CSlave *candidate, uint8_t address, bool broadcast,
  52                           I2CNodeList *current_devs);
  53 };
  54
  55 struct I2CSlave {
  56     DeviceState qdev;
  57
  58     /* Remaining fields for internal use by the I2C code.  */
  59     uint8_t address;
  60 };
  61
  62 #define TYPE_I2C_BUS "i2c-bus"
  63 OBJECT_DECLARE_SIMPLE_TYPE(I2CBus, I2C_BUS)
  64
  65 typedef struct I2CNode I2CNode;
  66
  67 struct I2CNode {
  68     I2CSlave *elt;
  69     QLIST_ENTRY(I2CNode) next;
  70 };
  71
  72 typedef QLIST_HEAD(I2CNodeList, I2CNode) I2CNodeList;
  73
  74 struct I2CBus {
  75     BusState qbus;
  76     I2CNodeList current_devs;
  77     uint8_t saved_address;
  78     bool broadcast;
  79 };
  80
  81 I2CBus *i2c_init_bus(DeviceState *parent, const char *name);
  82 void i2c_set_slave_address(I2CSlave *dev, uint8_t address);
  83 int i2c_bus_busy(I2CBus *bus);
  84 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv);
  85 void i2c_end_transfer(I2CBus *bus);
  86 void i2c_nack(I2CBus *bus);
  87 int i2c_send(I2CBus *bus, uint8_t data);
  88 uint8_t i2c_recv(I2CBus *bus);
  89 bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
  90                   I2CNodeList *current_devs);
  91
  92 /**
  93  * Create an I2C slave device on the heap.
  94  * @name: a device type name
  95  * @addr: I2C address of the slave when put on a bus
  96  *
  97  * This only initializes the device state structure and allows
  98  * properties to be set. Type @name must exist. The device still
  99  * needs to be realized. See qdev-core.h.
 100  */
 101 I2CSlave *i2c_slave_new(const char *name, uint8_t addr);
 102
 103 /**
 104  * Create and realize an I2C slave device on the heap.
 105  * @bus: I2C bus to put it on
 106  * @name: I2C slave device type name
 107  * @addr: I2C address of the slave when put on a bus
 108  *
 109  * Create the device state structure, initialize it, put it on the
 110  * specified @bus, and drop the reference to it (the device is realized).
 111  */
 112 I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr);
 113
 114 /**
 115  * Realize and drop a reference an I2C slave device
 116  * @dev: I2C slave device to realize
 117  * @bus: I2C bus to put it on
 118  * @addr: I2C address of the slave on the bus
 119  * @errp: pointer to NULL initialized error object
 120  *
 121  * Returns: %true on success, %false on failure.
 122  *
 123  * Call 'realize' on @dev, put it on the specified @bus, and drop the
 124  * reference to it.
 125  *
 126  * This function is useful if you have created @dev via qdev_new(),
 127  * i2c_slave_new() or i2c_slave_try_new() (which take a reference to
 128  * the device it returns to you), so that you can set properties on it
 129  * before realizing it. If you don't need to set properties then
 130  * i2c_slave_create_simple() is probably better (as it does the create,
 131  * init and realize in one step).
 132  *
 133  * If you are embedding the I2C slave into another QOM device and
 134  * initialized it via some variant on object_initialize_child() then
 135  * do not use this function, because that family of functions arrange
 136  * for the only reference to the child device to be held by the parent
 137  * via the child<> property, and so the reference-count-drop done here
 138  * would be incorrect.  (Instead you would want i2c_slave_realize(),
 139  * which doesn't currently exist but would be trivial to create if we
 140  * had any code that wanted it.)
 141  */
 142 bool i2c_slave_realize_and_unref(I2CSlave *dev, I2CBus *bus, Error **errp);
 143
 144 extern const VMStateDescription vmstate_i2c_slave;
 145
 146 #define VMSTATE_I2C_SLAVE(_field, _state) {                          \
 147     .name       = (stringify(_field)),                               \
 148     .size       = sizeof(I2CSlave),                                  \
 149     .vmsd       = &vmstate_i2c_slave,                                \
 150     .flags      = VMS_STRUCT,                                        \
 151     .offset     = vmstate_offset_value(_state, _field, I2CSlave),    \
 152 }
 153
 154 #endif