[SANTINO][PMIC] Force DDR voltage to 1.35V

Needed because some boards come with PMIC pre-programmed for 1.5V.

Ideally this should be done before initializing the DRAM but, due to
lack of internal SRAM of the MCU, requires a bigger effort to be
implemented.

board/seco/imx6dl_santino/imx6dl_santino.c

@@ -35,6 +35,7 @@
 #include <input.h>
 #include <power/pmic.h>
 #include <power/pfuze100_pmic.h>
+#include <power/pfuze3000_pmic.h>
 #include "../common/pfuze.h"
 #include <usb.h>
 #include <usb/ehci-ci.h>
@@ -82,7 +83,7 @@ DECLARE_GLOBAL_DATA_PTR;
 	PAD_CTL_PUS_47K_UP  | PAD_CTL_SPEED_LOW |		\
 	PAD_CTL_DSE_80ohm   | PAD_CTL_SRE_FAST  | PAD_CTL_HYS)
 
-
+#define PFUZE3000_SW3_REG_to_MVOLTS(x)      ((x) * 500 + 9000)
 #define I2C_PMIC	1
 
 #define I2C_PAD MUX_PAD_CTRL(I2C_PAD_CTRL)
@@ -333,6 +334,17 @@ int power_init_board(void)
 	if (ret < 0)
 		return ret;
 
+	/* set DDR_1_5V to 1.350V */
+	reg = pmic_reg_read(dev, PFUZE3000_SW3VOLT);
+	reg &= ~0x0f;
+	reg |= PFUZE3000_SW3_SETP(13500);
+	ret = pmic_reg_write(dev, PFUZE3000_SW3VOLT, reg);
+	reg = pmic_reg_read(dev, PFUZE3000_SW3VOLT);
+	if (ret)
+		return ret;
+	
+	printf("DDR3 Voltage: %u mV\n", PFUZE3000_SW3_REG_to_MVOLTS(reg));
+
 	return 0;
 }