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stm32: Rework register access on stm32f0_adc.c 

Avoid read-modify-write operations where possible.  The register
values are in a known state so prefer absolute writes.

Improve handling of race conditions with hardware updates.

Remove the adc reference from "struct gpio_adc" as it is a constant.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2021-12-19 20:56:34 -05:00
parent 20ac48f680
commit 88325b6c93
1 changed files with 25 additions and 34 deletions
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59
src/stm32/stm32f0_adc.c
View File

@ -38,38 +38,23 @@ gpio_adc_setup(uint32_t pin)
break;
}
// Determine which ADC block to use
ADC_TypeDef *adc = ADC1;
uint32_t adc_base = ADC1_BASE;
// Enable the ADC
if (!is_enabled_pclock(adc_base)) {
enable_pclock(adc_base);
if (!is_enabled_pclock(ADC1_BASE)) {
enable_pclock(ADC1_BASE);
ADC_TypeDef *adc = ADC1;
// 100: 41.5 ADC clock cycles
adc->SMPR |= ~ADC_SMPR_SMP_Msk | ADC_SMPR_SMP_2;
adc->CFGR2 |= ADC_CFGR2_CKMODE;
adc->CFGR1 &= ~ADC_CFGR1_AUTOFF;
adc->CFGR1 |= ADC_CFGR1_EXTSEL;
adc->SMPR = 4 << ADC_SMPR_SMP_Pos;
// do not enable ADC before calibration
adc->CR &= ~ADC_CR_ADEN;
while (adc->CR & ADC_CR_ADEN)
;
while (adc->CFGR1 & ADC_CFGR1_DMAEN)
;
// start calibration and wait for completion
adc->CR |= ADC_CR_ADCAL;
adc->CR = ADC_CR_ADCAL;
while (adc->CR & ADC_CR_ADCAL)
;
// if not enabled
if (!(adc->CR & ADC_CR_ADEN)) {
adc->ISR |= ADC_ISR_ADRDY;
adc->CR |= ADC_CR_ADEN;
while (!(ADC1->ISR & ADC_ISR_ADRDY))
;
}
adc->ISR = ADC_ISR_ADRDY;
adc->CR = ADC_CR_ADEN;
while (!(adc->ISR & ADC_ISR_ADRDY))
;
}
if (pin == ADC_TEMPERATURE_PIN)
@ -77,7 +62,7 @@ gpio_adc_setup(uint32_t pin)
else
gpio_peripheral(pin, GPIO_ANALOG, 0);
return (struct gpio_adc){ .adc = adc, .chan = 1 << chan };
return (struct gpio_adc){ .chan = 1 << chan };
}
// Try to sample a value. Returns zero if sample ready, otherwise
@ -86,13 +71,16 @@ gpio_adc_setup(uint32_t pin)
uint32_t
gpio_adc_sample(struct gpio_adc g)
{
ADC_TypeDef *adc = g.adc;
if (adc->ISR & ADC_ISR_EOC && adc->CHSELR == g.chan)
return 0;
ADC_TypeDef *adc = ADC1;
if (adc->CR & ADC_CR_ADSTART)
goto need_delay;
if (adc->ISR & ADC_ISR_EOC) {
if (adc->CHSELR == g.chan)
return 0;
goto need_delay;
}
adc->CHSELR = g.chan;
adc->CR |= ADC_CR_ADSTART;
adc->CR = ADC_CR_ADSTART;
need_delay:
return timer_from_us(10);
@ -102,8 +90,7 @@ need_delay:
uint16_t
gpio_adc_read(struct gpio_adc g)
{
ADC_TypeDef *adc = g.adc;
adc->ISR &= ~ADC_ISR_EOSEQ;
ADC_TypeDef *adc = ADC1;
return adc->DR;
}
@ -111,9 +98,13 @@ gpio_adc_read(struct gpio_adc g)
void
gpio_adc_cancel_sample(struct gpio_adc g)
{
ADC_TypeDef *adc = g.adc;
ADC_TypeDef *adc = ADC1;
irqstatus_t flag = irq_save();
if (!(adc->ISR & ADC_ISR_EOC) && adc->CHSELR == g.chan)
adc->CR |= ADC_CR_ADSTP;
if (adc->CHSELR == g.chan) {
if (adc->CR & ADC_CR_ADSTART)
adc->CR = ADC_CR_ADSTP;
if (adc->ISR & ADC_ISR_EOC)
gpio_adc_read(g);
}
irq_restore(flag);
}