Added default CS behaviour for SSI slaves. SSI devices can set a property
to enable CS behaviour which will create a GPIO on the device which is the
CS. Tristating of the bus on SSI transfers is implemented.
Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwa...@petalogix.com>
---
hw/ssd0323.c | 6 ++++++
hw/ssi-sd.c | 6 ++++++
hw/ssi.c | 39 ++++++++++++++++++++++++++++++++++++++-
hw/ssi.h | 27 +++++++++++++++++++++++++++
4 files changed, 77 insertions(+), 1 deletions(-)
diff --git a/hw/ssd0323.c b/hw/ssd0323.c
index b0b2e94..db16d20 100644
--- a/hw/ssd0323.c
+++ b/hw/ssd0323.c
@@ -277,6 +277,7 @@ static void ssd0323_cd(void *opaque, int n, int level)
static void ssd0323_save(QEMUFile *f, void *opaque)
{
+ SSISlave *ss = SSI_SLAVE(opaque);
ssd0323_state *s = (ssd0323_state *)opaque;
int i;
@@ -294,10 +295,13 @@ static void ssd0323_save(QEMUFile *f, void *opaque)
qemu_put_be32(f, s->remap);
qemu_put_be32(f, s->mode);
qemu_put_buffer(f, s->framebuffer, sizeof(s->framebuffer));
+
+ qemu_put_be32(f, ss->cs ? 1 : 0);
}
static int ssd0323_load(QEMUFile *f, void *opaque, int version_id)
{
+ SSISlave *ss = SSI_SLAVE(opaque);
ssd0323_state *s = (ssd0323_state *)opaque;
int i;
@@ -319,6 +323,8 @@ static int ssd0323_load(QEMUFile *f, void *opaque, int
version_id)
s->mode = qemu_get_be32(f);
qemu_get_buffer(f, s->framebuffer, sizeof(s->framebuffer));
+ ss->cs = !!qemu_get_be32(f);
+
return 0;
}
diff --git a/hw/ssi-sd.c b/hw/ssi-sd.c
index b519bdb..6fd9ab9 100644
--- a/hw/ssi-sd.c
+++ b/hw/ssi-sd.c
@@ -197,6 +197,7 @@ static uint32_t ssi_sd_transfer(SSISlave *dev, uint32_t val)
static void ssi_sd_save(QEMUFile *f, void *opaque)
{
+ SSISlave *ss = SSI_SLAVE(opaque);
ssi_sd_state *s = (ssi_sd_state *)opaque;
int i;
@@ -209,10 +210,13 @@ static void ssi_sd_save(QEMUFile *f, void *opaque)
qemu_put_be32(f, s->arglen);
qemu_put_be32(f, s->response_pos);
qemu_put_be32(f, s->stopping);
+
+ qemu_put_be32(f, ss->cs ? 1 : 0);
}
static int ssi_sd_load(QEMUFile *f, void *opaque, int version_id)
{
+ SSISlave *ss = SSI_SLAVE(opaque);
ssi_sd_state *s = (ssi_sd_state *)opaque;
int i;
@@ -229,6 +233,8 @@ static int ssi_sd_load(QEMUFile *f, void *opaque, int
version_id)
s->response_pos = qemu_get_be32(f);
s->stopping = qemu_get_be32(f);
+ ss->cs = !!qemu_get_be32(f);
+
return 0;
}
diff --git a/hw/ssi.c b/hw/ssi.c
index 2db88fc..2e4f2fe 100644
--- a/hw/ssi.c
+++ b/hw/ssi.c
@@ -27,19 +27,55 @@ static const TypeInfo ssi_bus_info = {
.instance_size = sizeof(SSIBus),
};
+static void ssi_cs_default(void *opaque, int n, int level)
+{
+ SSISlave *s = SSI_SLAVE(opaque);
+ bool cs = !!level;
+ assert(n == 0);
+ if (s->cs != cs) {
+ SSISlaveClass *ssc = SSI_SLAVE_GET_CLASS(s);
+ if (ssc->set_cs) {
+ ssc->set_cs(s, cs);
+ }
+ }
+ s->cs = cs;
+}
+
+static uint32_t ssi_transfer_raw_default(SSISlave *dev, uint32_t val)
+{
+ SSISlaveClass *ssc = SSI_SLAVE_GET_CLASS(dev);
+
+ if ((dev->cs && ssc->cs_polarity == SSI_CS_HIGH) ||
+ (!dev->cs && ssc->cs_polarity == SSI_CS_LOW) ||
+ ssc->cs_polarity == SSI_CS_NONE) {
+ return ssc->transfer(dev, val);
+ }
+ return 0;
+}
+
static int ssi_slave_init(DeviceState *dev)
{
SSISlave *s = SSI_SLAVE(dev);
SSISlaveClass *ssc = SSI_SLAVE_GET_CLASS(s);
+ if (ssc->transfer_raw == ssi_transfer_raw_default &&
+ ssc->cs_polarity != SSI_CS_NONE) {
+ qdev_init_gpio_in(&s->qdev, ssi_cs_default, 1);
+ }
+
return ssc->init(s);
}
static void ssi_slave_class_init(ObjectClass *klass, void *data)
{
+ SSISlaveClass *ssc = SSI_SLAVE_CLASS(klass);
DeviceClass *dc = DEVICE_CLASS(klass);
+
dc->init = ssi_slave_init;
dc->bus_type = TYPE_SSI_BUS;
+ if (!ssc->transfer_raw) {
+ ssc->transfer_raw = ssi_transfer_raw_default;
+ }
}
static TypeInfo ssi_slave_info = {
@@ -74,7 +110,7 @@ uint32_t ssi_transfer(SSIBus *bus, uint32_t val)
QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
SSISlave *slave = SSI_SLAVE(kid->child);
ssc = SSI_SLAVE_GET_CLASS(slave);
- r |= ssc->transfer(slave, val);
+ r |= ssc->transfer_raw(slave, val);
}
return r;
@@ -86,6 +122,7 @@ const VMStateDescription vmstate_ssi_slave = {
.minimum_version_id = 1,
.minimum_version_id_old = 1,
.fields = (VMStateField[]) {
+ VMSTATE_BOOL(cs, SSISlave),
VMSTATE_END_OF_LIST()
}
};
diff --git a/hw/ssi.h b/hw/ssi.h
index 975f9fb..5b69a3b 100644
--- a/hw/ssi.h
+++ b/hw/ssi.h
@@ -23,16 +23,43 @@ typedef struct SSISlave SSISlave;
#define SSI_SLAVE_GET_CLASS(obj) \
OBJECT_GET_CLASS(SSISlaveClass, (obj), TYPE_SSI_SLAVE)
+typedef enum {
+ SSI_CS_NONE = 0,
+ SSI_CS_LOW,
+ SSI_CS_HIGH,
+} SSICSMode;
+
/* Slave devices. */
typedef struct SSISlaveClass {
DeviceClass parent_class;
int (*init)(SSISlave *dev);
+
+ /* 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 assoicated 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 behvaiour override this to take control
+ * of the CS behvaiour 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 the to parent bus
+ */
+ uint32_t (*transfer_raw)(SSISlave *dev, uint32_t val);
} SSISlaveClass;
struct SSISlave {
DeviceState qdev;
+
+ /* Chip select state */
+ bool cs;
};
#define SSI_SLAVE_FROM_QDEV(dev) DO_UPCAST(SSISlave, qdev, dev)
--
1.7.0.4
