[PATCH v4 2/4] hw/i2c: add match method for device search

[Patrick Venture <venture@google.com>]

At the start of an i2c transaction, the i2c bus searches its list of
children to identify which devices correspond to the address (or
broadcast).  Now the I2CSlave device has a method "match" that
encapsulates the lookup behavior. This allows the behavior to be changed
to support devices, such as i2c muxes.

Tested: A BMC firmware was booted to userspace and i2c devices were
detected.

Signed-off-by: Patrick Venture <venture@google.com>
Reviewed-by: Hao Wu <wuhaotsh@google.com>
---
 hw/i2c/core.c        | 23 +++++++++++++++++++----
 include/hw/i2c/i2c.h | 11 +++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/hw/i2c/core.c b/hw/i2c/core.c
index 21ec52ac5a..d03b0eea5c 100644
--- a/hw/i2c/core.c
+++ b/hw/i2c/core.c
@@ -118,10 +118,9 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, int recv)
         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);
+            sc = I2C_SLAVE_GET_CLASS(candidate);
+            if (sc->match_and_add(candidate, address, bus->broadcast,
+                                  &bus->current_devs)) {
                 if (!bus->broadcast) {
                     break;
                 }
@@ -290,12 +289,28 @@ 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 = {
diff --git a/include/hw/i2c/i2c.h b/include/hw/i2c/i2c.h
index 1f7c268c86..9b8b95ff4a 100644
--- a/include/hw/i2c/i2c.h
+++ b/include/hw/i2c/i2c.h
@@ -16,6 +16,7 @@ enum i2c_event {
     I2C_NACK /* Masker NACKed a receive byte.  */
 };
 
+typedef struct I2CNodeList I2CNodeList;
 
 #define TYPE_I2C_SLAVE "i2c-slave"
 OBJECT_DECLARE_TYPE(I2CSlave, I2CSlaveClass,
@@ -39,6 +40,16 @@ struct I2CSlaveClass {
      * return code is not used and should be zero.
      */
     int (*event)(I2CSlave *s, enum i2c_event event);
+
+    /*
+     * Check if this device matches the address provided.  Returns bool of
+     * true if it matches (or broadcast), and updates the device list, false
+     * otherwise.
+     *
+     * If broadcast is true, match should add the device and return true.
+     */
+    bool (*match_and_add)(I2CSlave *candidate, uint8_t address, bool broadcast,
+                          I2CNodeList *current_devs);
 };
 
 struct I2CSlave {
-- 
2.31.1.295.g9ea45b61b8-goog