hw/sd: Add sdbus_write_data() to write multiples bytes on the data line

Add a sdbus_write_data() method to write multiple bytes on the
data line of a SD bus.
We might improve the tracing later, for now keep logging each
byte individually.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200814092346.21825-5-f4bug@amsat.org>

hw/sd/core.c

@@ -114,6 +114,21 @@ void sdbus_write_byte(SDBus *sdbus, uint8_t value)
     }
 }
 
+void sdbus_write_data(SDBus *sdbus, const void *buf, size_t length)
+{
+    SDState *card = get_card(sdbus);
+    const uint8_t *data = buf;
+
+    if (card) {
+        SDCardClass *sc = SD_CARD_GET_CLASS(card);
+
+        for (size_t i = 0; i < length; i++) {
+            trace_sdbus_write(sdbus_name(sdbus), data[i]);
+            sc->write_byte(card, data[i]);
+        }
+    }
+}
+
 uint8_t sdbus_read_byte(SDBus *sdbus)
 {
     SDState *card = get_card(sdbus);

include/hw/sd/sd.h

@@ -175,6 +175,15 @@ void sdbus_write_byte(SDBus *sd, uint8_t value);
  * Return: byte value read
  */
 uint8_t sdbus_read_byte(SDBus *sd);
+/**
+ * Write data to a SD bus.
+ * @sdbus: bus
+ * @buf: data to write
+ * @length: number of bytes to write
+ *
+ * Write multiple bytes of data on the data lines of a SD bus.
+ */
+void sdbus_write_data(SDBus *sdbus, const void *buf, size_t length);
 bool sdbus_data_ready(SDBus *sd);
 bool sdbus_get_inserted(SDBus *sd);
 bool sdbus_get_readonly(SDBus *sd);