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, 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 108