ARM: mxs: allow boards to select DC-DC switching clock source

For some board designs, it might be useful to switch the DC-DC
clock source to something else rather the default 24 MHz, e.g.
for EMI reasons.

For this, override the mxs_power_setup_dcdc_clocksource function
in your board support files.

Example:
void mxs_power_setup_dcdc_clocksource(void)
{
    mxs_power_switch_dcdc_clocksource(POWER_MISC_FREQSEL_20MHZ);
}

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>

diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
index 1972de81a8edd2f542814922fb5485ec7e52c409..1ec8e2b6438beba535b5f2ff10de62a978cbf64b 100644 (file)
--- a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
+++ b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
@@ -247,6 +247,39 @@ static void mxs_power_setup_5v_detect(void)
                        POWER_5VCTRL_PWRUP_VBUS_CMPS);
 }
 
+/**
+ * mxs_power_switch_dcdc_clocksource() - Switch PLL clock for DC-DC converters
+ * @freqsel:   One of the POWER_MISC_FREQSEL_xxx defines to select the clock
+ *
+ * This function configures and then enables an alternative PLL clock source
+ * for the DC-DC converters.
+ */
+void mxs_power_switch_dcdc_clocksource(uint32_t freqsel)
+{
+       struct mxs_power_regs *power_regs =
+               (struct mxs_power_regs *)MXS_POWER_BASE;
+
+       /* Select clocksource for DC-DC converters */
+       clrsetbits_le32(&power_regs->hw_power_misc,
+                       POWER_MISC_FREQSEL_MASK,
+                       freqsel);
+       setbits_le32(&power_regs->hw_power_misc,
+                       POWER_MISC_SEL_PLLCLK);
+}
+
+/**
+ * mxs_power_setup_dcdc_clocksource() - Setup PLL clock source for DC-DC converters
+ *
+ * Normally, there is no need to switch DC-DC clocksource. This is the reason,
+ * why this function is a stub and does nothing. However, boards can implement
+ * this function when required and call mxs_power_switch_dcdc_clocksource() to
+ * switch to an alternative clock source.
+ */
+__weak void mxs_power_setup_dcdc_clocksource(void)
+{
+       debug("SPL: Using default DC-DC clocksource\n");
+}
+
 /**
  * mxs_src_power_init() - Preconfigure the power block
  *
@@ -872,6 +905,7 @@ static void mxs_power_configure_power_source(void)
 
        debug("SPL: Configuring power source\n");
 
+       mxs_power_setup_dcdc_clocksource();
        mxs_src_power_init();
 
        if (readl(&power_regs->hw_power_sts) & POWER_STS_VDD5V_GT_VDDIO) {

diff --git a/arch/arm/include/asm/arch-mxs/sys_proto.h b/arch/arm/include/asm/arch-mxs/sys_proto.h
index 20ff101a2bf64898f6bb497d8aa0b8fbe5679649..f2b075e14ffbbcd8325574894585793b525ef373 100644 (file)
--- a/arch/arm/include/asm/arch-mxs/sys_proto.h
+++ b/arch/arm/include/asm/arch-mxs/sys_proto.h
@@ -25,6 +25,8 @@ int mxsmmc_initialize(bd_t *bis, int id, int (*wp)(int), int (*cd)(int));
 void mxs_common_spl_init(const uint32_t arg, const uint32_t *resptr,
                         const iomux_cfg_t *iomux_setup,
                         const unsigned int iomux_size);
+
+void mxs_power_switch_dcdc_clocksource(uint32_t freqsel);
 #endif
 
 struct mxs_pair {