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/* QEMU Synchronous Serial Interface support. */
/*
* In principle SSI is a point-point interface. As such the qemu
* implementation has a single slave device on a "bus".
* However it is fairly common for boards to have multiple slaves
* connected to a single master, and select devices with an external
* chip select. This is implemented in qemu by having an explicit mux device.
* It is assumed that master and slave are both using the same transfer
* width.
*/
#ifndef QEMU_SSI_H
#define QEMU_SSI_H
#include "hw/qdev-core.h"
#include "qom/object.h"
typedef enum SSICSMode SSICSMode;
#define TYPE_SSI_SLAVE "ssi-slave"
OBJECT_DECLARE_TYPE(SSISlave, SSISlaveClass,
SSI_SLAVE)
#define SSI_GPIO_CS "ssi-gpio-cs"
enum SSICSMode {
SSI_CS_NONE = 0,
SSI_CS_LOW,
SSI_CS_HIGH,
};
/* Slave devices. */
struct SSISlaveClass {
DeviceClass parent_class;
void (*realize)(SSISlave *dev, Error **errp);
/* if you have standard or no CS behaviour, just override transfer.
* This is called when the device cs is active (true by default).
*/
uint32_t (*transfer)(SSISlave *dev, uint32_t val);
/* called when the CS line changes. Optional, devices only need to implement
* this if they have side effects associated with the cs line (beyond
* tristating the txrx lines).
*/
int (*set_cs)(SSISlave *dev, bool select);
/* define whether or not CS exists and is active low/high */
SSICSMode cs_polarity;
/* if you have non-standard CS behaviour override this to take control
* of the CS behaviour at the device level. transfer, set_cs, and
* cs_polarity are unused if this is overwritten. Transfer_raw will
* always be called for the device for every txrx access to the parent bus
*/
uint32_t (*transfer_raw)(SSISlave *dev, uint32_t val);
};
struct SSISlave {
DeviceState parent_obj;
/* Chip select state */
bool cs;
};
extern const VMStateDescription vmstate_ssi_slave;
#define VMSTATE_SSI_SLAVE(_field, _state) { \
.name = (stringify(_field)), \
.size = sizeof(SSISlave), \
.vmsd = &vmstate_ssi_slave, \
.flags = VMS_STRUCT, \
.offset = vmstate_offset_value(_state, _field, SSISlave), \
}
DeviceState *ssi_create_slave(SSIBus *bus, const char *name);
/**
* ssi_realize_and_unref: realize and unref an SSI slave device
* @dev: SSI slave device to realize
* @bus: SSI bus to put it on
* @errp: error pointer
*
* Call 'realize' on @dev, put it on the specified @bus, and drop the
* reference to it. Errors are reported via @errp and by returning
* false.
*
* This function is useful if you have created @dev via qdev_new()
* (which takes a reference to the device it returns to you), so that
* you can set properties on it before realizing it. If you don't need
* to set properties then ssi_create_slave() is probably better (as it
* does the create, init and realize in one step).
*
* If you are embedding the SSI slave into another QOM device and
* initialized it via some variant on object_initialize_child() then
* do not use this function, because that family of functions arrange
* for the only reference to the child device to be held by the parent
* via the child<> property, and so the reference-count-drop done here
* would be incorrect. (Instead you would want ssi_realize(), which
* doesn't currently exist but would be trivial to create if we had
* any code that wanted it.)
*/
bool ssi_realize_and_unref(DeviceState *dev, SSIBus *bus, Error **errp);
/* Master interface. */
SSIBus *ssi_create_bus(DeviceState *parent, const char *name);
uint32_t ssi_transfer(SSIBus *bus, uint32_t val);
#endif
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