static void clock_module_disable(void)
{
/* bit0: FSPI interface tri-state */
IT83XX_SMFI_FLHCTRL3R |= (1 << 0);
/* bit7: USB pad power-on disable */
IT83XX_GCTRL_PMER2 &= ~(1 << 7);
clock_disable_peripheral((CGC_OFFSET_EGPC | CGC_OFFSET_CIR), 0, 0);
clock_disable_peripheral((CGC_OFFSET_SMBA | CGC_OFFSET_SMBB |
CGC_OFFSET_SMBC | CGC_OFFSET_SMBD | CGC_OFFSET_SMBE |
CGC_OFFSET_SMBF), 0, 0);
clock_disable_peripheral((CGC_OFFSET_SSPI | CGC_OFFSET_PECI |
CGC_OFFSET_USB), 0, 0);
}
static void adc_init(void)
{
int i;
/* Configure GPIOs */
configure_gpio();
/*
* Temporarily enable the PLL when turning on the clock to the ADC
* module, to work around chip errata (10.4). No need to notify
* other modules; the PLL isn't enabled long enough to matter.
*/
clock_enable_pll(1, 0);
/* Enable ADC0 module in run and sleep modes. */
clock_enable_peripheral(CGC_OFFSET_ADC, 0x1,
CGC_MODE_RUN | CGC_MODE_SLEEP);
/*
* Use external voltage references (VREFA+, VREFA-) instead of
* VDDA and GNDA.
*/
LM4_ADC_ADCCTL = 0x01;
/* Use internal oscillator */
LM4_ADC_ADCCC = 0x1;
/* Disable the PLL now that the ADC is using the internal oscillator */
clock_enable_pll(0, 0);
/* No tasks waiting yet */
for (i = 0; i < LM4_ADC_SEQ_COUNT; i++)
task_waiting_on_ss[i] = TASK_ID_INVALID;
/* Enable IRQs */
task_enable_irq(LM4_IRQ_ADC0_SS0);
task_enable_irq(LM4_IRQ_ADC0_SS1);
task_enable_irq(LM4_IRQ_ADC0_SS2);
task_enable_irq(LM4_IRQ_ADC0_SS3);
/* 2**6 = 64x oversampling */
LM4_ADC_ADCSAC = 6;
/* Initialize ADC sequencer */
for (i = 0; i < ADC_CH_COUNT; ++i)
adc_configure(adc_channels + i);
/* Disable ADC0 module until it is needed to conserve power. */
clock_disable_peripheral(CGC_OFFSET_ADC, 0x1,
CGC_MODE_RUN | CGC_MODE_SLEEP);
}
int adc_read_channel(enum adc_channel ch)
{
const struct adc_t *adc = adc_channels + ch;
static uint32_t ch_busy_mask;
static struct mutex adc_clock;
int rv;
/*
* TODO(crbug.com/314121): Generalize ADC reads such that any task can
* trigger a read of any channel.
*/
/*
* Enable ADC clock and set a bit in ch_busy_mask to signify that this
* channel is busy. Note, this function may be called from multiple
* tasks, but each channel may be read by only one task. If assert
* fails, then it means multiple tasks are trying to read same channel.
*/
mutex_lock(&adc_clock);
ASSERT(!(ch_busy_mask & (1UL << ch)));
clock_enable_peripheral(CGC_OFFSET_ADC, 0x1,
CGC_MODE_RUN | CGC_MODE_SLEEP);
ch_busy_mask |= (1UL << ch);
mutex_unlock(&adc_clock);
rv = flush_and_read(adc->sequencer);
/*
* If no ADC channels are busy, then disable ADC clock to conserve
* power.
*/
mutex_lock(&adc_clock);
ch_busy_mask &= ~(1UL << ch);
if (!ch_busy_mask)
clock_disable_peripheral(CGC_OFFSET_ADC, 0x1,
CGC_MODE_RUN | CGC_MODE_SLEEP);
mutex_unlock(&adc_clock);
if (rv == ADC_READ_ERROR)
return ADC_READ_ERROR;
return rv * adc->factor_mul / adc->factor_div + adc->shift;
}