[PATCH v1 4/4] board: verdin-am62: set cpu core voltage depending on speed grade

[Max Krummenacher]

On Thu, Jan 18, 2024 at 10:50:07AM +0100, Max Krummenacher wrote:
> On Wed, Jan 17, 2024 at 11:16:49AM +0100, Max Krummenacher wrote:
> > From: Max Krummenacher <max.krummenacher at toradex.com>
> > 
> > Speed grade T requires the VDD_CORE voltage to be 0.85V if using
> > the maximum core frequency.
> > 
> > Speed grades G, K, S allow the VDD_CORE voltage to be 0.75V up to the
> > maximum core frequency but allow to run at 0.85V.
> > 
> > For efficiency in manufacturing and code maintenance we use 0.85V for
> > the PMIC defaults and device tree settings and dynamically adjust the
> > voltage in the PMIC and device tree to 0.75V for lower speed SKU to
> > gain more than 100mW power consumption reduction.
> > 
> > Signed-off-by: Max Krummenacher <max.krummenacher at toradex.com>
> > ---
> > 
> >  board/toradex/verdin-am62/verdin-am62.c | 47 +++++++++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> > 
> > diff --git a/board/toradex/verdin-am62/verdin-am62.c b/board/toradex/verdin-am62/verdin-am62.c
> > index 4e912b5f32f..8b9db224069 100644
> > --- a/board/toradex/verdin-am62/verdin-am62.c
> > +++ b/board/toradex/verdin-am62/verdin-am62.c
> > @@ -13,10 +13,13 @@
> >  #include <fdt_support.h>
> >  #include <init.h>
> >  #include <k3-ddrss.h>
> > +#include <power/regulator.h>
> 
> In the !DM_REGULATOR case regulator.h assumes errno.h to be already included.
> This happens when compiling the R5 SPL.
> 
> Will fix this in a v2 of the series.

Actually we can go on with the series. While it is true that errno.h is not
included in regulator.h, the required header is included and its definitions
available.

I will create a separate patch which cleans up the headers, so that they
become self contained.

Max

> 
> Max
> 
> >  #include <spl.h>
> >  
> >  #include "../common/tdx-cfg-block.h"
> >  
> > +#define VDD_CORE_REG "buck1"
> > +
> >  DECLARE_GLOBAL_DATA_PTR;
> >  
> >  int board_init(void)
> > @@ -49,9 +52,37 @@ int board_fit_config_name_match(const char *name)
> >  }
> >  #endif
> >  
> > +static u32 get_vdd_core_nominal(void)
> > +{
> > +	int core_uvolt;
> > +
> > +	switch (k3_get_speed_grade()) {
> > +	case 'G':
> > +	case 'K':
> > +	case 'S':
> > +		core_uvolt = 750000;
> > +		break;
> > +	case 'T':
> > +	default:
> > +		core_uvolt = 850000;
> > +		break;
> > +	}
> > +	return core_uvolt;
> > +}
> > +
> >  #if IS_ENABLED(CONFIG_OF_LIBFDT) && IS_ENABLED(CONFIG_OF_BOARD_SETUP)
> >  int ft_board_setup(void *blob, struct bd_info *bd)
> >  {
> > +	int core_uvolt;
> > +
> > +	core_uvolt = get_vdd_core_nominal();
> > +	if (core_uvolt != 850000) {
> > +		do_fixup_by_path_u32(blob, "/bus at f0000/i2c at 20000000/pmic at 30/regulators/buck1",
> > +				     "regulator-max-microvolt", core_uvolt, 0);
> > +		do_fixup_by_path_u32(blob, "/bus at f0000/i2c at 20000000/pmic at 30/regulators/buck1",
> > +				     "regulator-min-microvolt", core_uvolt, 0);
> > +	}
> > +
> >  	return ft_common_board_setup(blob, bd);
> >  }
> >  #endif
> > @@ -86,6 +117,22 @@ static void select_dt_from_module_version(void)
> >  
> >  int board_late_init(void)
> >  {
> > +	int ret;
> > +	int core_uvolt;
> > +	struct udevice *dev = NULL;
> > +
> > +	core_uvolt = get_vdd_core_nominal();
> > +	if (core_uvolt != 850000) {
> > +		/* Set CPU core voltage to 0.75V for slower speed grades */
> > +		ret = regulator_get_by_devname(VDD_CORE_REG, &dev);
> > +		if (ret)
> > +			pr_err("VDD CORE Regulator get error: %d\n", ret);
> > +
> > +		ret = regulator_set_value_force(dev, core_uvolt);
> > +		if (ret)
> > +			pr_err("VDD CORE Regulator value setting error: %d\n", ret);
> > +	}
> > +
> >  	select_dt_from_module_version();
> >  
> >  	return 0;
> > -- 
> > 2.42.0
> >