zynq: slcr: Disable all level shifters

Disable all level shifters before enabling
the PS-to-PL level shifters as it would
be good to disable all level shifters before
enabling the PS-to-PL in order to ensure that
it is in proper state

Signed-off-by: Siva Durga Prasad Paladugu <sivadur@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/cpu/armv7/zynq/slcr.c

@@ -129,11 +129,18 @@ out:
 
 void zynq_slcr_devcfg_disable(void)
 {
+	u32 reg_val;
+
 	zynq_slcr_unlock();
 
 	/* Disable AXI interface by asserting FPGA resets */
 	writel(0xF, &slcr_base->fpga_rst_ctrl);
 
+	/* Disable Level shifters before setting PS-PL */
+	reg_val = readl(&slcr_base->lvl_shftr_en);
+	reg_val &= ~0xF;
+	writel(reg_val, &slcr_base->lvl_shftr_en);
+
 	/* Set Level Shifters DT618760 */
 	writel(0xA, &slcr_base->lvl_shftr_en);