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90d37239 PB |
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 | ||
a27bd6c7 | 14 | #include "hw/qdev-core.h" |
db1015e9 | 15 | #include "qom/object.h" |
90d37239 PB |
16 | |
17 | typedef struct SSISlave SSISlave; | |
8fd06719 AF |
18 | typedef struct SSISlaveClass SSISlaveClass; |
19 | typedef enum SSICSMode SSICSMode; | |
90d37239 | 20 | |
cd6c4cf2 AL |
21 | #define TYPE_SSI_SLAVE "ssi-slave" |
22 | #define SSI_SLAVE(obj) \ | |
23 | OBJECT_CHECK(SSISlave, (obj), TYPE_SSI_SLAVE) | |
24 | #define SSI_SLAVE_CLASS(klass) \ | |
25 | OBJECT_CLASS_CHECK(SSISlaveClass, (klass), TYPE_SSI_SLAVE) | |
26 | #define SSI_SLAVE_GET_CLASS(obj) \ | |
27 | OBJECT_GET_CLASS(SSISlaveClass, (obj), TYPE_SSI_SLAVE) | |
28 | ||
de77914e PC |
29 | #define SSI_GPIO_CS "ssi-gpio-cs" |
30 | ||
8fd06719 | 31 | enum SSICSMode { |
66530953 PC |
32 | SSI_CS_NONE = 0, |
33 | SSI_CS_LOW, | |
34 | SSI_CS_HIGH, | |
8fd06719 | 35 | }; |
66530953 | 36 | |
90d37239 | 37 | /* Slave devices. */ |
8fd06719 | 38 | struct SSISlaveClass { |
cd6c4cf2 AL |
39 | DeviceClass parent_class; |
40 | ||
7673bb4c | 41 | void (*realize)(SSISlave *dev, Error **errp); |
66530953 PC |
42 | |
43 | /* if you have standard or no CS behaviour, just override transfer. | |
44 | * This is called when the device cs is active (true by default). | |
45 | */ | |
90d37239 | 46 | uint32_t (*transfer)(SSISlave *dev, uint32_t val); |
66530953 PC |
47 | /* called when the CS line changes. Optional, devices only need to implement |
48 | * this if they have side effects associated with the cs line (beyond | |
49 | * tristating the txrx lines). | |
50 | */ | |
51 | int (*set_cs)(SSISlave *dev, bool select); | |
52 | /* define whether or not CS exists and is active low/high */ | |
53 | SSICSMode cs_polarity; | |
54 | ||
55 | /* if you have non-standard CS behaviour override this to take control | |
56 | * of the CS behaviour at the device level. transfer, set_cs, and | |
57 | * cs_polarity are unused if this is overwritten. Transfer_raw will | |
58 | * always be called for the device for every txrx access to the parent bus | |
59 | */ | |
60 | uint32_t (*transfer_raw)(SSISlave *dev, uint32_t val); | |
8fd06719 | 61 | }; |
90d37239 PB |
62 | |
63 | struct SSISlave { | |
1f760d5f | 64 | DeviceState parent_obj; |
66530953 PC |
65 | |
66 | /* Chip select state */ | |
67 | bool cs; | |
90d37239 PB |
68 | }; |
69 | ||
66530953 PC |
70 | extern const VMStateDescription vmstate_ssi_slave; |
71 | ||
72 | #define VMSTATE_SSI_SLAVE(_field, _state) { \ | |
73 | .name = (stringify(_field)), \ | |
74 | .size = sizeof(SSISlave), \ | |
75 | .vmsd = &vmstate_ssi_slave, \ | |
76 | .flags = VMS_STRUCT, \ | |
77 | .offset = vmstate_offset_value(_state, _field, SSISlave), \ | |
78 | } | |
79 | ||
90d37239 | 80 | DeviceState *ssi_create_slave(SSIBus *bus, const char *name); |
581e109d PM |
81 | /** |
82 | * ssi_realize_and_unref: realize and unref an SSI slave device | |
83 | * @dev: SSI slave device to realize | |
84 | * @bus: SSI bus to put it on | |
85 | * @errp: error pointer | |
86 | * | |
87 | * Call 'realize' on @dev, put it on the specified @bus, and drop the | |
88 | * reference to it. Errors are reported via @errp and by returning | |
89 | * false. | |
90 | * | |
91 | * This function is useful if you have created @dev via qdev_new() | |
92 | * (which takes a reference to the device it returns to you), so that | |
93 | * you can set properties on it before realizing it. If you don't need | |
94 | * to set properties then ssi_create_slave() is probably better (as it | |
95 | * does the create, init and realize in one step). | |
96 | * | |
97 | * If you are embedding the SSI slave into another QOM device and | |
98 | * initialized it via some variant on object_initialize_child() then | |
99 | * do not use this function, because that family of functions arrange | |
100 | * for the only reference to the child device to be held by the parent | |
101 | * via the child<> property, and so the reference-count-drop done here | |
102 | * would be incorrect. (Instead you would want ssi_realize(), which | |
103 | * doesn't currently exist but would be trivial to create if we had | |
104 | * any code that wanted it.) | |
105 | */ | |
106 | bool ssi_realize_and_unref(DeviceState *dev, SSIBus *bus, Error **errp); | |
90d37239 PB |
107 | |
108 | /* Master interface. */ | |
02e2da45 | 109 | SSIBus *ssi_create_bus(DeviceState *parent, const char *name); |
90d37239 PB |
110 | |
111 | uint32_t ssi_transfer(SSIBus *bus, uint32_t val); | |
112 | ||
113 | #endif |