hw/ssi.h

   1 /* QEMU Synchronous Serial Interface support.  */
   2
   3 /* In principle SSI is a point-point interface.  As such the qemu
   4    implementation has a single slave device on a "bus".
   5    However it is fairly common for boards to have multiple slaves
   6    connected to a single master, and select devices with an external
   7    chip select.  This is implemented in qemu by having an explicit mux device.
   8    It is assumed that master and slave are both using the same transfer width.
   9    */
  10
  11 #ifndef QEMU_SSI_H
  12 #define QEMU_SSI_H
  13
  14 #include "hw/qdev.h"
  15
  16 typedef struct SSISlave SSISlave;
  17
  18 #define TYPE_SSI_SLAVE "ssi-slave"
  19 #define SSI_SLAVE(obj) \
  20      OBJECT_CHECK(SSISlave, (obj), TYPE_SSI_SLAVE)
  21 #define SSI_SLAVE_CLASS(klass) \
  22      OBJECT_CLASS_CHECK(SSISlaveClass, (klass), TYPE_SSI_SLAVE)
  23 #define SSI_SLAVE_GET_CLASS(obj) \
  24      OBJECT_GET_CLASS(SSISlaveClass, (obj), TYPE_SSI_SLAVE)
  25
  26 typedef enum {
  27     SSI_CS_NONE = 0,
  28     SSI_CS_LOW,
  29     SSI_CS_HIGH,
  30 } SSICSMode;
  31
  32 /* Slave devices.  */
  33 typedef struct SSISlaveClass {
  34     DeviceClass parent_class;
  35
  36     int (*init)(SSISlave *dev);
  37
  38     /* if you have standard or no CS behaviour, just override transfer.
  39      * This is called when the device cs is active (true by default).
  40      */
  41     uint32_t (*transfer)(SSISlave *dev, uint32_t val);
  42     /* called when the CS line changes. Optional, devices only need to implement
  43      * this if they have side effects associated with the cs line (beyond
  44      * tristating the txrx lines).
  45      */
  46     int (*set_cs)(SSISlave *dev, bool select);
  47     /* define whether or not CS exists and is active low/high */
  48     SSICSMode cs_polarity;
  49
  50     /* if you have non-standard CS behaviour override this to take control
  51      * of the CS behaviour at the device level. transfer, set_cs, and
  52      * cs_polarity are unused if this is overwritten. Transfer_raw will
  53      * always be called for the device for every txrx access to the parent bus
  54      */
  55     uint32_t (*transfer_raw)(SSISlave *dev, uint32_t val);
  56 } SSISlaveClass;
  57
  58 struct SSISlave {
  59     DeviceState qdev;
  60
  61     /* Chip select state */
  62     bool cs;
  63 };
  64
  65 #define SSI_SLAVE_FROM_QDEV(dev) DO_UPCAST(SSISlave, qdev, dev)
  66 #define FROM_SSI_SLAVE(type, dev) DO_UPCAST(type, ssidev, dev)
  67
  68 extern const VMStateDescription vmstate_ssi_slave;
  69
  70 #define VMSTATE_SSI_SLAVE(_field, _state) {                          \
  71     .name       = (stringify(_field)),                               \
  72     .size       = sizeof(SSISlave),                                  \
  73     .vmsd       = &vmstate_ssi_slave,                                \
  74     .flags      = VMS_STRUCT,                                        \
  75     .offset     = vmstate_offset_value(_state, _field, SSISlave),    \
  76 }
  77
  78 DeviceState *ssi_create_slave(SSIBus *bus, const char *name);
  79 DeviceState *ssi_create_slave_no_init(SSIBus *bus, const char *name);
  80
  81 /* Master interface.  */
  82 SSIBus *ssi_create_bus(DeviceState *parent, const char *name);
  83
  84 uint32_t ssi_transfer(SSIBus *bus, uint32_t val);
  85
  86 /* Automatically connect all children nodes a spi controller as slaves */
  87 void ssi_auto_connect_slaves(DeviceState *parent, qemu_irq *cs_lines,
  88                              SSIBus *bus);
  89
  90 /* max111x.c */
  91 void max111x_set_input(DeviceState *dev, int line, uint8_t value);
  92
  93 #endif