[Qemu-devel] [PATCH V3 3/8] i2c: implement broadcast write.

[fred . konrad]

From: KONRAD Frederic <fred.kon...@greensocs.com>

This does a write to every slaves when the I2C bus get a write to address 0.

Signed-off-by: KONRAD Frederic <fred.kon...@greensocs.com>
---
 hw/i2c/core.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

diff --git a/hw/i2c/core.c b/hw/i2c/core.c
index e0f92de..db9413f 100644
--- a/hw/i2c/core.c
+++ b/hw/i2c/core.c
@@ -14,6 +14,7 @@ struct I2CBus
     BusState qbus;
     I2CSlave *current_dev;
     uint8_t saved_address;
+    bool broadcast;
 };
 
 static Property i2c_props[] = {
@@ -55,6 +56,7 @@ static const VMStateDescription vmstate_i2c_bus = {
     .post_load = i2c_bus_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT8(saved_address, I2CBus),
+        VMSTATE_BOOL(broadcast, I2CBus),
         VMSTATE_END_OF_LIST()
     }
 };
@@ -66,6 +68,7 @@ I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
 
     bus = I2C_BUS(qbus_create(TYPE_I2C_BUS, parent, name));
     vmstate_register(NULL, -1, &vmstate_i2c_bus, bus);
+
     return bus;
 }
 
@@ -88,6 +91,19 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, int 
recv)
     I2CSlave *slave = NULL;
     I2CSlaveClass *sc;
 
+    if (address == 0x00) {
+        /* This is a broadcast. */
+        bus->broadcast = true;
+        QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
+            I2CSlave *dev = I2C_SLAVE(kid->child);
+            sc = I2C_SLAVE_GET_CLASS(dev);
+            if (sc->event) {
+                sc->event(dev, recv ? I2C_START_RECV : I2C_START_SEND);
+            }
+        }
+        return 0;
+    }
+
     QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
         DeviceState *qdev = kid->child;
         I2CSlave *candidate = I2C_SLAVE(qdev);
@@ -113,9 +129,22 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, int 
recv)
 
 void i2c_end_transfer(I2CBus *bus)
 {
+    BusChild *kid;
     I2CSlave *dev = bus->current_dev;
     I2CSlaveClass *sc;
 
+    if (bus->broadcast) {
+        QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
+            I2CSlave *dev = I2C_SLAVE(kid->child);
+            sc = I2C_SLAVE_GET_CLASS(dev);
+            if (sc->event) {
+                sc->event(dev, I2C_FINISH);
+            }
+        }
+        bus->broadcast = false;
+        return;
+    }
+
     if (!dev) {
         return;
     }
@@ -130,8 +159,22 @@ void i2c_end_transfer(I2CBus *bus)
 
 int i2c_send(I2CBus *bus, uint8_t data)
 {
+    BusChild *kid;
     I2CSlave *dev = bus->current_dev;
     I2CSlaveClass *sc;
+    int ret = 0;
+
+    if (bus->broadcast) {
+        QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
+            I2CSlave *dev = I2C_SLAVE(kid->child);
+            sc = I2C_SLAVE_GET_CLASS(dev);
+            bus->broadcast = true;
+            if (sc->send) {
+                ret |= sc->send(dev, data);
+            }
+        }
+        return ret;
+    }
 
     if (!dev) {
         return -1;
@@ -150,7 +193,7 @@ int i2c_recv(I2CBus *bus)
     I2CSlave *dev = bus->current_dev;
     I2CSlaveClass *sc;
 
-    if (!dev) {
+    if ((!dev) || (bus->broadcast)) {
         return -1;
     }
 
-- 
1.9.0