+ /*
+ * Assuming Vcc = 2.0V (lowest speed)
+ *
+ * REVISIT: If we add an rtc_init() function we can do this
+ * step just once.
+ */
+ if (!slave) {
+ slave = spi_setup_slave(0, CFG_SPI_RTC_DEVID, 600000,
+ SPI_MODE_3 | SPI_CS_HIGH);
+ if (!slave)
+ return;
+ }
+
+ if (spi_claim_bus(slave))
+ return;
+