From fe21eaf92de4d78413e69c95ba23a869e17454f7 Mon Sep 17 00:00:00 2001 From: Michael Heimpold Date: Sun, 13 Dec 2015 12:08:37 +0100 Subject: 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 Cc: Marek Vasut Cc: Otavio Salvador Cc: Fabio Estevam Acked-by: Marek Vasut --- arch/arm/cpu/arm926ejs/mxs/spl_power_init.c | 34 +++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'arch/arm/cpu/arm926ejs') 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) { -- cgit v1.1