[U-Boot] [PATCH v2] 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_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 {
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.
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
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
participants (2)
-
Marek Vasut -
Michael Heimpold