On Friday, December 11, 2015 at 12:05:36 AM, Michael Heimpold wrote:
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.
Can you elaborate on this ? Also, is there gonna be a user for this?
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@heimpold.de Cc: Marek Vasut marex@denx.de Cc: Otavio Salvador otavio@ossystems.com.br Cc: Fabio Estevam fabio.estevam@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()
Please make sure this is compatible with kerneldoc.
- 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);
This function does not need to be exported if it's __weak I believe.