hw/i2c: Introduce i2c_start_recv() and i2c_start_send()

To ease reviewing code using the I2C bus API, introduce the
i2c_start_recv() and i2c_start_send() helpers which don't
take the confusing 'is_recv' boolean argument.

Use these new helpers in the SMBus / AUX bus models.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

hw/i2c/core.c

@@ -180,6 +180,16 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, bool is_recv)
                                                : I2C_START_SEND);
 }
 
+int i2c_start_recv(I2CBus *bus, uint8_t address)
+{
+    return i2c_do_start_transfer(bus, address, I2C_START_RECV);
+}
+
+int i2c_start_send(I2CBus *bus, uint8_t address)
+{
+    return i2c_do_start_transfer(bus, address, I2C_START_SEND);
+}
+
 void i2c_end_transfer(I2CBus *bus)
 {
     I2CSlaveClass *sc;

hw/i2c/pm_smbus.c

@@ -128,14 +128,14 @@ static void smb_transaction(PMSMBus *s)
          * So at least Linux may or may not set the read bit here.
          * So just ignore the read bit for this command.
          */
-        if (i2c_start_transfer(bus, addr, 0)) {
+        if (i2c_start_send(bus, addr)) {
             goto error;
         }
         ret = i2c_send(bus, s->smb_data1);
         if (ret) {
             goto error;
         }
-        if (i2c_start_transfer(bus, addr, 1)) {
+        if (i2c_start_recv(bus, addr)) {
             goto error;
         }
         s->in_i2c_block_read = true;

hw/i2c/smbus_master.c

@@ -29,7 +29,7 @@ int smbus_receive_byte(I2CBus *bus, uint8_t addr)
 {
     uint8_t data;
 
-    if (i2c_start_transfer(bus, addr, 1)) {
+    if (i2c_start_recv(bus, addr)) {
         return -1;
     }
     data = i2c_recv(bus);
@@ -40,7 +40,7 @@ int smbus_receive_byte(I2CBus *bus, uint8_t addr)
 
 int smbus_send_byte(I2CBus *bus, uint8_t addr, uint8_t data)
 {
-    if (i2c_start_transfer(bus, addr, 0)) {
+    if (i2c_start_send(bus, addr)) {
         return -1;
     }
     i2c_send(bus, data);
@@ -51,11 +51,11 @@ int smbus_send_byte(I2CBus *bus, uint8_t addr, uint8_t data)
 int smbus_read_byte(I2CBus *bus, uint8_t addr, uint8_t command)
 {
     uint8_t data;
-    if (i2c_start_transfer(bus, addr, 0)) {
+    if (i2c_start_send(bus, addr)) {
         return -1;
     }
     i2c_send(bus, command);
-    if (i2c_start_transfer(bus, addr, 1)) {
+    if (i2c_start_recv(bus, addr)) {
         i2c_end_transfer(bus);
         return -1;
     }
@@ -67,7 +67,7 @@ int smbus_read_byte(I2CBus *bus, uint8_t addr, uint8_t command)
 
 int smbus_write_byte(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t data)
 {
-    if (i2c_start_transfer(bus, addr, 0)) {
+    if (i2c_start_send(bus, addr)) {
         return -1;
     }
     i2c_send(bus, command);
@@ -79,11 +79,11 @@ int smbus_write_byte(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t data)
 int smbus_read_word(I2CBus *bus, uint8_t addr, uint8_t command)
 {
     uint16_t data;
-    if (i2c_start_transfer(bus, addr, 0)) {
+    if (i2c_start_send(bus, addr)) {
         return -1;
     }
     i2c_send(bus, command);
-    if (i2c_start_transfer(bus, addr, 1)) {
+    if (i2c_start_recv(bus, addr)) {
         i2c_end_transfer(bus);
         return -1;
     }
@@ -96,7 +96,7 @@ int smbus_read_word(I2CBus *bus, uint8_t addr, uint8_t command)
 
 int smbus_write_word(I2CBus *bus, uint8_t addr, uint8_t command, uint16_t data)
 {
-    if (i2c_start_transfer(bus, addr, 0)) {
+    if (i2c_start_send(bus, addr)) {
         return -1;
     }
     i2c_send(bus, command);
@@ -113,12 +113,12 @@ int smbus_read_block(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t *data,
     int i;
 
     if (send_cmd) {
-        if (i2c_start_transfer(bus, addr, 0)) {
+        if (i2c_start_send(bus, addr)) {
             return -1;
         }
         i2c_send(bus, command);
     }
-    if (i2c_start_transfer(bus, addr, 1)) {
+    if (i2c_start_recv(bus, addr)) {
         if (send_cmd) {
             i2c_end_transfer(bus);
         }
@@ -149,7 +149,7 @@ int smbus_write_block(I2CBus *bus, uint8_t addr, uint8_t command, uint8_t *data,
         len = 32;
     }
 
-    if (i2c_start_transfer(bus, addr, 0)) {
+    if (i2c_start_send(bus, addr)) {
         return -1;
     }
     i2c_send(bus, command);

hw/misc/auxbus.c

@@ -135,7 +135,7 @@ AUXReply aux_request(AUXBus *bus, AUXCommand cmd, uint32_t address,
             i2c_end_transfer(i2c_bus);
         }
 
-        if (i2c_start_transfer(i2c_bus, address, true)) {
+        if (i2c_start_recv(i2c_bus, address)) {
             ret = AUX_I2C_NACK;
             break;
         }
@@ -151,7 +151,7 @@ AUXReply aux_request(AUXBus *bus, AUXCommand cmd, uint32_t address,
             i2c_end_transfer(i2c_bus);
         }
 
-        if (i2c_start_transfer(i2c_bus, address, false)) {
+        if (i2c_start_send(i2c_bus, address)) {
             ret = AUX_I2C_NACK;
             break;
         }
@@ -179,7 +179,7 @@ AUXReply aux_request(AUXBus *bus, AUXCommand cmd, uint32_t address,
             /*
              * No transactions started..
              */
-            if (i2c_start_transfer(i2c_bus, address, false)) {
+            if (i2c_start_send(i2c_bus, address)) {
                 break;
             }
         } else if ((address != bus->last_i2c_address) ||
@@ -188,7 +188,7 @@ AUXReply aux_request(AUXBus *bus, AUXCommand cmd, uint32_t address,
              * Transaction started but we need to restart..
              */
             i2c_end_transfer(i2c_bus);
-            if (i2c_start_transfer(i2c_bus, address, false)) {
+            if (i2c_start_send(i2c_bus, address)) {
                 break;
             }
         }
@@ -210,7 +210,7 @@ AUXReply aux_request(AUXBus *bus, AUXCommand cmd, uint32_t address,
             /*
              * No transactions started..
              */
-            if (i2c_start_transfer(i2c_bus, address, true)) {
+            if (i2c_start_recv(i2c_bus, address)) {
                 break;
             }
         } else if ((address != bus->last_i2c_address) ||
@@ -219,7 +219,7 @@ AUXReply aux_request(AUXBus *bus, AUXCommand cmd, uint32_t address,
              * Transaction started but we need to restart..
              */
             i2c_end_transfer(i2c_bus);
-            if (i2c_start_transfer(i2c_bus, address, true)) {
+            if (i2c_start_recv(i2c_bus, address)) {
                 break;
             }
         }

include/hw/i2c/i2c.h

@@ -88,9 +88,33 @@ int i2c_bus_busy(I2CBus *bus);
  * @address: address of the slave
  * @is_recv: indicates the transfer direction
  *
+ * When @is_recv is a known boolean constant, use the
+ * i2c_start_recv() or i2c_start_send() helper instead.
+ *
  * Returns: 0 on success, -1 on error
  */
 int i2c_start_transfer(I2CBus *bus, uint8_t address, bool is_recv);
+
+/**
+ * i2c_start_recv: start a 'receive' transfer on an I2C bus.
+ *
+ * @bus: #I2CBus to be used
+ * @address: address of the slave
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int i2c_start_recv(I2CBus *bus, uint8_t address);
+
+/**
+ * i2c_start_send: start a 'send' transfer on an I2C bus.
+ *
+ * @bus: #I2CBus to be used
+ * @address: address of the slave
+ *
+ * Returns: 0 on success, -1 on error
+ */
+int i2c_start_send(I2CBus *bus, uint8_t address);
+
 void i2c_end_transfer(I2CBus *bus);
 void i2c_nack(I2CBus *bus);
 int i2c_send(I2CBus *bus, uint8_t data);