* [U-Boot] [PATCH v2] ARM: mxs: allow boards to select DC-DC switching clock source
@ 2015-12-10 23:05 Michael Heimpold
2015-12-12 1:42 ` Marek Vasut
0 siblings, 1 reply; 4+ messages in thread
From: Michael Heimpold @ 2015-12-10 23:05 UTC (permalink / raw)
To: u-boot
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@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()
+ *
+ * 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
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [U-Boot] [PATCH v2] ARM: mxs: allow boards to select DC-DC switching clock source
2015-12-10 23:05 [U-Boot] [PATCH v2] ARM: mxs: allow boards to select DC-DC switching clock source Michael Heimpold
@ 2015-12-12 1:42 ` Marek Vasut
2015-12-12 9:02 ` Michael Heimpold
0 siblings, 1 reply; 4+ messages in thread
From: Marek Vasut @ 2015-12-12 1:42 UTC (permalink / raw)
To: u-boot
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.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [U-Boot] [PATCH v2] ARM: mxs: allow boards to select DC-DC switching clock source
2015-12-12 1:42 ` Marek Vasut
@ 2015-12-12 9:02 ` Michael Heimpold
2015-12-12 15:33 ` Marek Vasut
0 siblings, 1 reply; 4+ messages in thread
From: Michael Heimpold @ 2015-12-12 9:02 UTC (permalink / raw)
To: u-boot
Hi Marek,
Am Saturday 12 December 2015, 02:42:47 schrieb Marek Vasut:
> 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?
Sure. Every DC-DC switching frequency also generates some harmonics.
On usual board design, this is not a huge problem, but on our I2SE
Duckbill EnOcean devices, the EnOcean transceiver sits very close to the
i.MX because of stacked PCBs. Our hardware guys measured, that the
harmonics overlaps a little bit with the EnOcean spectrum. Changing
the DC-DC frequency results in others harmonics, which do not interfere
anymore.
I already sent a patch for adding Duckbill support and I'm preparing a v2
which would include this topic, so this would be the first user of this
feature.
>
> > 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.
Ah, yes. Will do in v3.
>
> > + * 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.
mxs_power_setup_dcdc_clocksource is the weak function, not
mxs_power_select_dcdc_clocksource so I think this is needed.
Regards,
Michael
^ permalink raw reply [flat|nested] 4+ messages in thread
* [U-Boot] [PATCH v2] ARM: mxs: allow boards to select DC-DC switching clock source
2015-12-12 9:02 ` Michael Heimpold
@ 2015-12-12 15:33 ` Marek Vasut
0 siblings, 0 replies; 4+ messages in thread
From: Marek Vasut @ 2015-12-12 15:33 UTC (permalink / raw)
To: u-boot
On Saturday, December 12, 2015 at 10:02:30 AM, Michael Heimpold wrote:
> Hi Marek,
Hi!
> Am Saturday 12 December 2015, 02:42:47 schrieb Marek Vasut:
> > 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?
>
> Sure. Every DC-DC switching frequency also generates some harmonics.
> On usual board design, this is not a huge problem, but on our I2SE
> Duckbill EnOcean devices, the EnOcean transceiver sits very close to the
> i.MX because of stacked PCBs. Our hardware guys measured, that the
> harmonics overlaps a little bit with the EnOcean spectrum. Changing
> the DC-DC frequency results in others harmonics, which do not interfere
> anymore.
> I already sent a patch for adding Duckbill support and I'm preparing a v2
> which would include this topic, so this would be the first user of this
> feature.
Ah, thanks for the detailed explanation, got it.
> > > 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)
> > > +{
Looks like the comment and name of the function do not match here ("select" vs
"switch").
> > > + 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.
>
> Ah, yes. Will do in v3.
>
> > > + * 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");
Shouldn't this call the mxs_power_select_dcdc_clocksource() then somehow ?
> > > +}
> > > +
> > > +/**
> > >
> > > * 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.
>
> mxs_power_setup_dcdc_clocksource is the weak function, not
> mxs_power_select_dcdc_clocksource so I think this is needed.
So the user is supposed to call this function from the board code, right?
Best regards,
Marek Vasut
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-12-12 15:33 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2015-12-10 23:05 [U-Boot] [PATCH v2] ARM: mxs: allow boards to select DC-DC switching clock source Michael Heimpold
2015-12-12 1:42 ` Marek Vasut
2015-12-12 9:02 ` Michael Heimpold
2015-12-12 15:33 ` Marek Vasut
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