+static int rockchip_spi_calc_modclk(ulong max_freq)
+{
+ /*
+ * While this is not strictly correct for the RK3368, as the
+ * GPLL will be 576MHz, things will still work, as the
+ * clk_set_rate(...) implementation in our clock-driver will
+ * chose the next closest rate not exceeding what we request
+ * based on the output of this function.
+ */
+
+ unsigned div;
+ const unsigned long gpll_hz = 594000000UL;
+
+ /*
+ * We need to find an input clock that provides at least twice
+ * the maximum frequency and can be generated from the assumed
+ * speed of GPLL (594MHz) using an integer divider.
+ *
+ * To give us more achievable bitrates at higher speeds (these
+ * are generated by dividing by an even 16-bit integer from
+ * this frequency), we try to have an input frequency of at
+ * least 4x our max_freq.
+ */
+
+ div = DIV_ROUND_UP(gpll_hz, max_freq * 4);
+ return gpll_hz / div;
+}
+