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soc: nordic: nrf54l: Clean up internal capacitance calculations.

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Code responsible for internal capacitor values containted
leftover workarounds in the calculations after PS update.
Removed redundant conversions and cleaned up both code
and comments to align both LFXO and HFXO calculation.

Signed-off-by: Michał Stasiak <michal.stasiak@nordicsemi.no>
This commit is contained in:
Michał Stasiak 2025-05-09 09:41:27 +02:00 • committed by Benjamin Cabé
commit 63f2fe9dd4
1 changed files with 32 additions and 39 deletions
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71
soc/nordic/nrf54l/soc.c
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@ -17,7 +17,6 @@
#include <zephyr/devicetree.h> #include <zephyr/devicetree.h>
#include <zephyr/kernel.h> #include <zephyr/kernel.h>
#include <zephyr/devicetree.h>
#include <zephyr/init.h> #include <zephyr/init.h>
#include <zephyr/logging/log.h> #include <zephyr/logging/log.h>
#include <zephyr/cache.h> #include <zephyr/cache.h>
@ -50,16 +49,20 @@ static inline void power_and_clock_configuration(void)
*/ */
#if DT_ENUM_HAS_VALUE(LFXO_NODE, load_capacitors, internal) #if DT_ENUM_HAS_VALUE(LFXO_NODE, load_capacitors, internal)
uint32_t xosc32ktrim = NRF_FICR->XOSC32KTRIM; uint32_t xosc32ktrim = NRF_FICR->XOSC32KTRIM;
/* The SLOPE field is in the two's complement form, hence this special
uint32_t offset_k = * handling. Ideally, it would result in just one SBFX instruction for
(xosc32ktrim & FICR_XOSC32KTRIM_OFFSET_Msk) >> FICR_XOSC32KTRIM_OFFSET_Pos; * extracting the slope value, at least gcc is capable of producing such
* output, but since the compiler apparently tries first to optimize
* additions and subtractions, it generates slightly less than optimal
* code.
*/
uint32_t slope_field_k = uint32_t slope_field_k =
(xosc32ktrim & FICR_XOSC32KTRIM_SLOPE_Msk) >> FICR_XOSC32KTRIM_SLOPE_Pos; (xosc32ktrim & FICR_XOSC32KTRIM_SLOPE_Msk) >> FICR_XOSC32KTRIM_SLOPE_Pos;
uint32_t slope_mask_k = FICR_XOSC32KTRIM_SLOPE_Msk >> FICR_XOSC32KTRIM_SLOPE_Pos; uint32_t slope_mask_k = FICR_XOSC32KTRIM_SLOPE_Msk >> FICR_XOSC32KTRIM_SLOPE_Pos;
uint32_t slope_sign_k = (slope_mask_k - (slope_mask_k >> 1)); uint32_t slope_sign_k = (slope_mask_k - (slope_mask_k >> 1));
int32_t slope_k = (int32_t)(slope_field_k ^ slope_sign_k) - (int32_t)slope_sign_k; int32_t slope_k = (int32_t)(slope_field_k ^ slope_sign_k) - (int32_t)slope_sign_k;
uint32_t offset_k =
(xosc32ktrim & FICR_XOSC32KTRIM_OFFSET_Msk) >> FICR_XOSC32KTRIM_OFFSET_Pos;
/* As specified in the nRF54L15 PS: /* As specified in the nRF54L15 PS:
* CAPVALUE = round( (2*CAPACITANCE - 12) * (FICR->XOSC32KTRIM.SLOPE + 0.765625 * 2^9)/(2^9) * CAPVALUE = round( (2*CAPACITANCE - 12) * (FICR->XOSC32KTRIM.SLOPE + 0.765625 * 2^9)/(2^9)
* + FICR->XOSC32KTRIM.OFFSET/(2^6) ); * + FICR->XOSC32KTRIM.OFFSET/(2^6) );
@ -67,29 +70,22 @@ static inline void power_and_clock_configuration(void)
* value between 4 pF and 18 pF in 0.5 pF steps. * value between 4 pF and 18 pF in 0.5 pF steps.
*/ */
/* Encoding of desired capacitance (single ended) to value required for INTCAP core uint32_t lfxo_intcap_femto_f = DT_PROP(LFXO_NODE, load_capacitance_femtofarad);
* calculation: (CAP_VAL - 4 pF)* 0.5
* That translate to ((CAP_VAL_FEMTO_F - 4000fF) * 2UL) / 1000UL
*
* NOTE: The desired capacitance value is used in encoded from in INTCAP calculation formula
* That is different than in case of HFXO.
*/
uint32_t cap_val_encoded = (((DT_PROP(LFXO_NODE, load_capacitance_femtofarad) - 4000UL)
* 2UL) / 1000UL);
/* Calculation of INTCAP code before rounding. Min that calculations here are done on /* Calculation of INTCAP code before rounding. Min that calculations here are done on
* values multiplied by 2^9, e.g. 0.765625 * 2^9 = 392. * values multiplied by 2^9, e.g. 0.765625 * 2^9 = 392.
* offset_k should be divided by 2^6, but to add it to value shifted by 2^9 we have to * offset_k should be divided by 2^6, but to add it to value shifted by 2^9 we have to
* multiply it be 2^3. * multiply it be 2^3. Capacitance value passed to the formula is in femto Farads to
* avoid floating point data type. Hence, offset_k needs to be multiplied by 1000.
*/ */
uint32_t mid_val = (2UL * cap_val_encoded - 12UL) * (uint32_t)(slope_k + 392UL) uint32_t lfxo_intcap_mid_val = (2UL * lfxo_intcap_femto_f - 12000UL)
+ (offset_k << 3UL); * (uint32_t)(slope_k + 392UL) + (offset_k << 3UL) * 1000UL;
/* Get integer part of the INTCAP code */ /* Get integer part of the INTCAP by dividing by 2^9 and convert to pico Farads. */
uint32_t lfxo_intcap = mid_val >> 9UL; uint32_t lfxo_intcap = lfxo_intcap_mid_val / 512000UL;
/* Round based on fractional part */ /* Round based on fractional part. */
if ((mid_val & BIT_MASK(9)) > (BIT_MASK(9) / 2)) { if (lfxo_intcap_mid_val % 512000UL >= 256000UL) {
lfxo_intcap++; lfxo_intcap++;
} }
@ -107,11 +103,11 @@ static inline void power_and_clock_configuration(void)
* additions and subtractions, it generates slightly less than optimal * additions and subtractions, it generates slightly less than optimal
* code. * code.
*/ */
uint32_t slope_field = uint32_t slope_field_m =
(xosc32mtrim & FICR_XOSC32MTRIM_SLOPE_Msk) >> FICR_XOSC32MTRIM_SLOPE_Pos; (xosc32mtrim & FICR_XOSC32MTRIM_SLOPE_Msk) >> FICR_XOSC32MTRIM_SLOPE_Pos;
uint32_t slope_mask = FICR_XOSC32MTRIM_SLOPE_Msk >> FICR_XOSC32MTRIM_SLOPE_Pos; uint32_t slope_mask_m = FICR_XOSC32MTRIM_SLOPE_Msk >> FICR_XOSC32MTRIM_SLOPE_Pos;
uint32_t slope_sign = (slope_mask - (slope_mask >> 1)); uint32_t slope_sign_m = (slope_mask_m - (slope_mask_m >> 1));
int32_t slope_m = (int32_t)(slope_field ^ slope_sign) - (int32_t)slope_sign; int32_t slope_m = (int32_t)(slope_field_m ^ slope_sign_m) - (int32_t)slope_sign_m;
uint32_t offset_m = uint32_t offset_m =
(xosc32mtrim & FICR_XOSC32MTRIM_OFFSET_Msk) >> FICR_XOSC32MTRIM_OFFSET_Pos; (xosc32mtrim & FICR_XOSC32MTRIM_OFFSET_Msk) >> FICR_XOSC32MTRIM_OFFSET_Pos;
/* As specified in the nRF54L15 PS: /* As specified in the nRF54L15 PS:
@ -121,22 +117,19 @@ static inline void power_and_clock_configuration(void)
* holding any value between 4.0 pF and 17.0 pF in 0.25 pF steps. * holding any value between 4.0 pF and 17.0 pF in 0.25 pF steps.
*/ */
/* NOTE 1: Requested HFXO internal capacitance in femto Faradas is used directly in formula uint32_t hfxo_intcap_femto_f = DT_PROP(HFXO_NODE, load_capacitance_femtofarad);
* to calculate INTCAP code. That is different than in case of LFXO.
* /* Capacitance value passed to the formula is in femto Farads to
* NOTE 2: PS formula uses piko Farads, the implementation of the formula uses femto Farads * avoid floating point data type. Hence, offset_m needs to be multiplied by 1000.
* to avoid use of floating point data type.
*/ */
uint32_t cap_val_femto_f = DT_PROP(HFXO_NODE, load_capacitance_femtofarad); uint32_t hfxo_intcap_mid_val = (((hfxo_intcap_femto_f - 5500UL)
* (uint32_t)(slope_m + 791UL)) + (offset_m << 2UL) * 1000UL) >> 8UL;
uint32_t mid_val_intcap = (((cap_val_femto_f - 5500UL) * (uint32_t)(slope_m + 791UL)) /* Convert the calculated value to piko Farads. */
+ (offset_m << 2UL) * 1000UL) >> 8UL; uint32_t hfxo_intcap = hfxo_intcap_mid_val / 1000;
/* Convert the calculated value to piko Farads */ /* Round based on fractional part. */
uint32_t hfxo_intcap = mid_val_intcap / 1000; if (hfxo_intcap_mid_val % 1000 >= 500) {
/* Round based on fractional part */
if (mid_val_intcap % 1000 >= 500) {
hfxo_intcap++; hfxo_intcap++;
} }