block/export: Add query-block-exports
[qemu.git] / include / hw / ssi / 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-core.h"
15 #include "qom/object.h"
16
17 typedef enum SSICSMode SSICSMode;
18
19 #define TYPE_SSI_SLAVE "ssi-slave"
20 OBJECT_DECLARE_TYPE(SSISlave, SSISlaveClass,
21 SSI_SLAVE)
22
23 #define SSI_GPIO_CS "ssi-gpio-cs"
24
25 enum SSICSMode {
26 SSI_CS_NONE = 0,
27 SSI_CS_LOW,
28 SSI_CS_HIGH,
29 };
30
31 /* Slave devices. */
32 struct SSISlaveClass {
33 DeviceClass parent_class;
34
35 void (*realize)(SSISlave *dev, Error **errp);
36
37 /* if you have standard or no CS behaviour, just override transfer.
38 * This is called when the device cs is active (true by default).
39 */
40 uint32_t (*transfer)(SSISlave *dev, uint32_t val);
41 /* called when the CS line changes. Optional, devices only need to implement
42 * this if they have side effects associated with the cs line (beyond
43 * tristating the txrx lines).
44 */
45 int (*set_cs)(SSISlave *dev, bool select);
46 /* define whether or not CS exists and is active low/high */
47 SSICSMode cs_polarity;
48
49 /* if you have non-standard CS behaviour override this to take control
50 * of the CS behaviour at the device level. transfer, set_cs, and
51 * cs_polarity are unused if this is overwritten. Transfer_raw will
52 * always be called for the device for every txrx access to the parent bus
53 */
54 uint32_t (*transfer_raw)(SSISlave *dev, uint32_t val);
55 };
56
57 struct SSISlave {
58 DeviceState parent_obj;
59
60 /* Chip select state */
61 bool cs;
62 };
63
64 extern const VMStateDescription vmstate_ssi_slave;
65
66 #define VMSTATE_SSI_SLAVE(_field, _state) { \
67 .name = (stringify(_field)), \
68 .size = sizeof(SSISlave), \
69 .vmsd = &vmstate_ssi_slave, \
70 .flags = VMS_STRUCT, \
71 .offset = vmstate_offset_value(_state, _field, SSISlave), \
72 }
73
74 DeviceState *ssi_create_slave(SSIBus *bus, const char *name);
75 /**
76 * ssi_realize_and_unref: realize and unref an SSI slave device
77 * @dev: SSI slave device to realize
78 * @bus: SSI bus to put it on
79 * @errp: error pointer
80 *
81 * Call 'realize' on @dev, put it on the specified @bus, and drop the
82 * reference to it. Errors are reported via @errp and by returning
83 * false.
84 *
85 * This function is useful if you have created @dev via qdev_new()
86 * (which takes a reference to the device it returns to you), so that
87 * you can set properties on it before realizing it. If you don't need
88 * to set properties then ssi_create_slave() is probably better (as it
89 * does the create, init and realize in one step).
90 *
91 * If you are embedding the SSI slave into another QOM device and
92 * initialized it via some variant on object_initialize_child() then
93 * do not use this function, because that family of functions arrange
94 * for the only reference to the child device to be held by the parent
95 * via the child<> property, and so the reference-count-drop done here
96 * would be incorrect. (Instead you would want ssi_realize(), which
97 * doesn't currently exist but would be trivial to create if we had
98 * any code that wanted it.)
99 */
100 bool ssi_realize_and_unref(DeviceState *dev, SSIBus *bus, Error **errp);
101
102 /* Master interface. */
103 SSIBus *ssi_create_bus(DeviceState *parent, const char *name);
104
105 uint32_t ssi_transfer(SSIBus *bus, uint32_t val);
106
107 #endif