Merge remote-tracking branch 'remotes/cminyard/tags/for-qemu-6.1-v1' into staging

Add a bus multiplexer device

This patch set adds a bus multiplexer and the necessary infrastructure
in the I2C code to allow it to work.

These are common on systems with lots of I2C devices, like an IPMI BMC.

# gpg: Signature made Thu 13 May 2021 22:48:07 BST
# gpg:                using RSA key FD0D5CE67CE0F59A6688268661F38C90919BFF81
# gpg: Good signature from "Corey Minyard <cminyard@mvista.com>" [unknown]
# gpg:                 aka "Corey Minyard <minyard@acm.org>" [unknown]
# gpg:                 aka "Corey Minyard <corey@minyard.net>" [unknown]
# gpg:                 aka "Corey Minyard <minyard@mvista.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: FD0D 5CE6 7CE0 F59A 6688  2686 61F3 8C90 919B FF81

* remotes/cminyard/tags/for-qemu-6.1-v1:
  hw/i2c: add pca954x i2c-mux switch
  hw/i2c: move search to i2c_scan_bus method
  hw/i2c: add match method for device search
  hw/i2c: name I2CNode list in I2CBus

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 42 insertions, 13 deletions

diff --git a/hw/i2c/core.c b/hw/i2c/core.c
index 21ec52ac5a..3a7bae311d 100644
--- a/hw/i2c/core.c
+++ b/hw/i2c/core.c
@@ -77,6 +77,30 @@ int i2c_bus_busy(I2CBus *bus)
     return !QLIST_EMPTY(&bus->current_devs);
 }
 
+bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
+                  I2CNodeList *current_devs)
+{
+    BusChild *kid;
+
+    QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        I2CSlave *candidate = I2C_SLAVE(qdev);
+        I2CSlaveClass *sc = I2C_SLAVE_GET_CLASS(candidate);
+
+        if (sc->match_and_add(candidate, address, broadcast, current_devs)) {
+            if (!broadcast) {
+                return true;
+            }
+        }
+    }
+
+    /*
+     * If broadcast was true, and the list was full or empty, return true. If
+     * broadcast was false, return false.
+     */
+    return broadcast;
+}
+
 /* TODO: Make this handle multiple masters.  */
 /*
  * Start or continue an i2c transaction.  When this is called for the
@@ -93,7 +117,6 @@ int i2c_bus_busy(I2CBus *bus)
  */
 int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
 {
-    BusChild *kid;
     I2CSlaveClass *sc;
     I2CNode *node;
     bool bus_scanned = false;
@@ -115,18 +138,8 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
      * terminating the previous transaction.
      */
     if (QLIST_EMPTY(&bus->current_devs)) {
-        QTAILQ_FOREACH(kid, &bus->qbus.children, sibling) {
-            DeviceState *qdev = kid->child;
-            I2CSlave *candidate = I2C_SLAVE(qdev);
-            if ((candidate->address == address) || (bus->broadcast)) {
-                node = g_malloc(sizeof(struct I2CNode));
-                node->elt = candidate;
-                QLIST_INSERT_HEAD(&bus->current_devs, node, next);
-                if (!bus->broadcast) {
-                    break;
-                }
-            }
-        }
+        /* Disregard whether devices were found. */
+        (void)i2c_scan_bus(bus, address, bus->broadcast, &bus->current_devs);
         bus_scanned = true;
     }
 
@@ -290,12 +303,28 @@ I2CSlave *i2c_slave_create_simple(I2CBus *bus, const char *name, uint8_t addr)
     return dev;
 }
 
+static bool i2c_slave_match(I2CSlave *candidate, uint8_t address,
+                            bool broadcast, I2CNodeList *current_devs)
+{
+    if ((candidate->address == address) || (broadcast)) {
+        I2CNode *node = g_malloc(sizeof(struct I2CNode));
+        node->elt = candidate;
+        QLIST_INSERT_HEAD(current_devs, node, next);
+        return true;
+    }
+
+    /* Not found and not broadcast. */
+    return false;
+}
+
 static void i2c_slave_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *k = DEVICE_CLASS(klass);
+    I2CSlaveClass *sc = I2C_SLAVE_CLASS(klass);
     set_bit(DEVICE_CATEGORY_MISC, k->categories);
     k->bus_type = TYPE_I2C_BUS;
     device_class_set_props(k, i2c_props);
+    sc->match_and_add = i2c_slave_match;
 }
 
 static const TypeInfo i2c_slave_type_info = {