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 ---

Changes in v3: - fixed and improved kerneldoc - renamed mxs_power_select_dcdc_clocksource to mxs_power_switch_dcdc_clocksource to fit the comment

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 | 34 +++++++++++++++++++++++++++++ arch/arm/include/asm/arch-mxs/sys_proto.h | 2 ++ 2 files changed, 36 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..1ec8e2b 100644 --- a/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c +++ b/arch/arm/cpu/arm926ejs/mxs/spl_power_init.c @@ -248,6 +248,39 @@ static void mxs_power_setup_5v_detect(void) }

/** + * 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 * * This function configures reasonable values for the DC-DC control loop @@ -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 20ff101..f2b075e 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_switch_dcdc_clocksource(uint32_t freqsel); #endif

struct mxs_pair {