ARM: imx6: disable bandgap self-bias after boot

[karo-tx-uboot.git] / arch / arm / cpu / armv7 / mx6 / soc.c

diff --git a/arch/arm/cpu/armv7/mx6/soc.c b/arch/arm/cpu/armv7/mx6/soc.c
index ee035c576e695e9c4afceb379d31e087cdb60b48..2fe069ec24e47e8ce8c708eba976779985b7c586 100644 (file)
--- a/arch/arm/cpu/armv7/mx6/soc.c
+++ b/arch/arm/cpu/armv7/mx6/soc.c
@@ -450,6 +450,22 @@ static void clear_mmdc_ch_mask(void)
        writel(0, &mxc_ccm->ccdr);
 }
 
+static void init_bandgap(void)
+{
+       struct anatop_regs *anatop = (struct anatop_regs *)ANATOP_BASE_ADDR;
+       /*
+        * Ensure the bandgap has stabilized.
+        */
+       while (!(readl(&anatop->ana_misc0) & 0x80))
+               ;
+       /*
+        * For best noise performance of the analog blocks using the
+        * outputs of the bandgap, the reftop_selfbiasoff bit should
+        * be set.
+        */
+       writel(BM_ANADIG_ANA_MISC0_REFTOP_SELBIASOFF, &anatop->ana_misc0_set);
+}
+
 #ifdef CONFIG_SOC_MX6SL
 static void set_preclk_from_osc(void)
 {
@@ -469,6 +485,13 @@ int arch_cpu_init(void)
        /* Need to clear MMDC_CHx_MASK to make warm reset work. */
        clear_mmdc_ch_mask();
 
+       /*
+        * Disable self-bias circuit in the analog bandap.
+        * The self-bias circuit is used by the bandgap during startup.
+        * This bit should be set after the bandgap has initialized.
+        */
+       init_bandgap();
+
        /*
         * When low freq boot is enabled, ROM will not set AHB
         * freq, so we need to ensure AHB freq is 132MHz in such