arm: mxs: Provide Kconfig option to disable battery charging at IMX28 PMU

This new Kconfig option allows disabling the in-PMU battery charging
block. This may be required when DCDC_BAT source is powered not from
battery, but from already regulated, good quality source.

Signed-off-by: Lukasz Majewski <lukma@denx.de>

arch/arm/cpu/arm926ejs/mxs/spl_power_init.c

@@ -756,6 +756,13 @@ static void mxs_batt_boot(void)
 		setbits_le32(&power_regs->hw_power_5vctrl,
 			     POWER_5VCTRL_ILIMIT_EQ_ZERO);
 
+	if (CONFIG_IS_ENABLED(MXS_PMU_DISABLE_BATT_CHARGE)) {
+		writel(POWER_CHARGE_PWD_BATTCHRG,
+		       &power_regs->hw_power_charge_set);
+		writel(POWER_5VCTRL_PWD_CHARGE_4P2_MASK,
+		       &power_regs->hw_power_5vctrl_set);
+	}
+
 	mxs_power_enable_4p2();
 }
 

arch/arm/mach-imx/mxs/Kconfig

@@ -59,6 +59,10 @@ config SPL_MXS_PMU_MINIMAL_VDD5V_CURRENT
 	  by the PMU is reduced to zero - the DCDC_BATT is used as
 	  the main power source for PMU.
 
+config SPL_MXS_PMU_DISABLE_BATT_CHARGE
+	bool "Disable Battery Charging in MX28 PMU"
+	default n
+
 source "board/freescale/mx28evk/Kconfig"
 source "board/liebherr/xea/Kconfig"