[U-Boot] [PATCH v2] ARM: mxs: allow boards to select DC-DC switching clock source
Michael Heimpold
mhei at heimpold.de
Fri Dec 11 00:05:36 CET 2015
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_select_dcdc_clocksource(POWER_MISC_FREQSEL_20MHZ);
}
Signed-off-by: Michael Heimpold <mhei at heimpold.de>
Cc: Marek Vasut <marex at denx.de>
Cc: Otavio Salvador <otavio at ossystems.com.br>
Cc: Fabio Estevam <fabio.estevam at freescale.com>
---
Changes in v2:
- use a weak function approach instead of ifdef'ery as suggested
by Marek Vasut
arch/arm/cpu/arm926ejs/mxs/spl_power_init.c | 31 +++++++++++++++++++++++++++++
arch/arm/include/asm/arch-mxs/sys_proto.h | 2 ++
2 files changed, 33 insertions(+)
diff --git a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
index 1972de8..64e215c 100644
--- a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
+++ b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
@@ -248,6 +248,36 @@ static void mxs_power_setup_5v_detect(void)
}
/**
+ * mxs_power_switch_dcdc_clocksource() - Switch PLL clock for DC-DC converters
+ *
+ * This function configures and then enables an alternative PLL clock source
+ * for the DC-DC converters.
+ */
+void mxs_power_select_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()
+ *
+ * Normally, there is no need to switch DC-DC clocksource. However, boards
+ * can implement this function when required.
+ */
+__weak void mxs_power_setup_dcdc_clocksource(void)
+{
+ debug("SPL: Using default DC-DC clocksource\n");
+}
+
+/**
* mxs_src_power_init() - Preconfigure the power block
*
* This function configures reasonable values for the DC-DC control loop
@@ -872,6 +902,7 @@ 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 20ff101..4160e43 100644
--- 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_select_dcdc_clocksource(uint32_t freqsel);
#endif
struct mxs_pair {
--
2.5.0
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