| 1 | /* QEMU Synchronous Serial Interface support. */ |
| 2 | |
| 3 | /* |
| 4 | * In principle SSI is a point-point interface. As such the qemu |
| 5 | * implementation has a single peripheral on a "bus". |
| 6 | * However it is fairly common for boards to have multiple peripherals |
| 7 | * connected to a single master, and select devices with an external |
| 8 | * chip select. This is implemented in qemu by having an explicit mux device. |
| 9 | * It is assumed that master and peripheral are both using the same transfer |
| 10 | * width. |
| 11 | */ |
| 12 | |
| 13 | #ifndef QEMU_SSI_H |
| 14 | #define QEMU_SSI_H |
| 15 | |
| 16 | #include "hw/core/qdev.h" |
| 17 | #include "qom/object.h" |
| 18 | |
| 19 | typedef enum SSICSMode SSICSMode; |
| 20 | |
| 21 | #define TYPE_SSI_PERIPHERAL "ssi-peripheral" |
| 22 | OBJECT_DECLARE_TYPE(SSIPeripheral, SSIPeripheralClass, |
| 23 | SSI_PERIPHERAL) |
| 24 | |
| 25 | #define SSI_GPIO_CS "ssi-gpio-cs" |
| 26 | |
| 27 | enum SSICSMode { |
| 28 | SSI_CS_NONE = 0, |
| 29 | SSI_CS_LOW, |
| 30 | SSI_CS_HIGH, |
| 31 | }; |
| 32 | |
| 33 | /* Peripherals. */ |
| 34 | struct SSIPeripheralClass { |
| 35 | DeviceClass parent_class; |
| 36 | |
| 37 | void (*realize)(SSIPeripheral *dev, Error **errp); |
| 38 | |
| 39 | /* if you have standard or no CS behaviour, just override transfer. |
| 40 | * This is called when the device cs is active (true by default). |
| 41 | * See ssi_transfer(). |
| 42 | */ |
| 43 | uint32_t (*transfer)(SSIPeripheral *dev, uint32_t val); |
| 44 | /* called when the CS line changes. Optional, devices only need to implement |
| 45 | * this if they have side effects associated with the cs line (beyond |
| 46 | * tristating the txrx lines). |
| 47 | */ |
| 48 | int (*set_cs)(SSIPeripheral *dev, bool select); |
| 49 | /* define whether or not CS exists and is active low/high */ |
| 50 | SSICSMode cs_polarity; |
| 51 | |
| 52 | /* if you have non-standard CS behaviour override this to take control |
| 53 | * of the CS behaviour at the device level. transfer, set_cs, and |
| 54 | * cs_polarity are unused if this is overwritten. Transfer_raw will |
| 55 | * always be called for the device for every txrx access to the parent bus |
| 56 | * See ssi_transfer(). |
| 57 | */ |
| 58 | uint32_t (*transfer_raw)(SSIPeripheral *dev, uint32_t val); |
| 59 | }; |
| 60 | |
| 61 | struct SSIPeripheral { |
| 62 | DeviceState parent_obj; |
| 63 | |
| 64 | /* cache the class */ |
| 65 | SSIPeripheralClass *spc; |
| 66 | |
| 67 | /* Chip select state */ |
| 68 | bool cs; |
| 69 | |
| 70 | /* Chip select index */ |
| 71 | uint8_t cs_index; |
| 72 | }; |
| 73 | |
| 74 | extern const VMStateDescription vmstate_ssi_peripheral; |
| 75 | |
| 76 | #define VMSTATE_SSI_PERIPHERAL(_field, _state) { \ |
| 77 | .name = (stringify(_field)), \ |
| 78 | .size = sizeof(SSIPeripheral), \ |
| 79 | .vmsd = &vmstate_ssi_peripheral, \ |
| 80 | .flags = VMS_STRUCT, \ |
| 81 | .offset = vmstate_offset_value(_state, _field, SSIPeripheral), \ |
| 82 | } |
| 83 | |
| 84 | DeviceState *ssi_create_peripheral(SSIBus *bus, const char *name); |
| 85 | /** |
| 86 | * ssi_realize_and_unref: realize and unref an SSI peripheral |
| 87 | * @dev: SSI peripheral to realize |
| 88 | * @bus: SSI bus to put it on |
| 89 | * @errp: error pointer |
| 90 | * |
| 91 | * Call 'realize' on @dev, put it on the specified @bus, and drop the |
| 92 | * reference to it. Errors are reported via @errp and by returning |
| 93 | * false. |
| 94 | * |
| 95 | * This function is useful if you have created @dev via qdev_new() |
| 96 | * (which takes a reference to the device it returns to you), so that |
| 97 | * you can set properties on it before realizing it. If you don't need |
| 98 | * to set properties then ssi_create_peripheral() is probably better (as it |
| 99 | * does the create, init and realize in one step). |
| 100 | * |
| 101 | * If you are embedding the SSI peripheral into another QOM device and |
| 102 | * initialized it via some variant on object_initialize_child() then |
| 103 | * do not use this function, because that family of functions arrange |
| 104 | * for the only reference to the child device to be held by the parent |
| 105 | * via the child<> property, and so the reference-count-drop done here |
| 106 | * would be incorrect. (Instead you would want ssi_realize(), which |
| 107 | * doesn't currently exist but would be trivial to create if we had |
| 108 | * any code that wanted it.) |
| 109 | */ |
| 110 | bool ssi_realize_and_unref(DeviceState *dev, SSIBus *bus, Error **errp); |
| 111 | |
| 112 | /* Master interface. */ |
| 113 | SSIBus *ssi_create_bus(DeviceState *parent, const char *name); |
| 114 | |
| 115 | /** |
| 116 | * Transfer a word on a SSI bus |
| 117 | * @bus: SSI bus |
| 118 | * @val: word to transmit |
| 119 | * |
| 120 | * At the same time, read a word and write the @val one on the SSI bus. |
| 121 | * |
| 122 | * SSI words might vary between 8 and 32 bits. The same number of bits |
| 123 | * written is received. |
| 124 | * |
| 125 | * Return: word value received |
| 126 | */ |
| 127 | uint32_t ssi_transfer(SSIBus *bus, uint32_t val); |
| 128 | |
| 129 | DeviceState *ssi_get_cs(SSIBus *bus, uint8_t cs_index); |
| 130 | |
| 131 | #endif |