cpu/sam0_common: implement periph_adc_continous

cpu/sam0_common/Kconfig

@@ -8,6 +8,7 @@
 config CPU_COMMON_SAM0
     bool
     select HAS_PERIPH_CPUID
+    select HAS_PERIPH_ADC_CONTINUOUS
     select HAS_PERIPH_FLASHPAGE
     select HAS_PERIPH_FLASHPAGE_IN_ADDRESS_SPACE
     select HAS_PERIPH_FLASHPAGE_PAGEWISE

cpu/sam0_common/Makefile.features

@@ -7,6 +7,7 @@ ifeq (,$(filter $(CPU_MODELS_WITHOUT_DMA),$(CPU_MODEL)))
   FEATURES_PROVIDED += periph_dma
 endif
 
+FEATURES_PROVIDED += periph_adc_continuous
 FEATURES_PROVIDED += periph_flashpage
 FEATURES_PROVIDED += periph_flashpage_in_address_space
 FEATURES_PROVIDED += periph_flashpage_pagewise

cpu/sam0_common/periph/adc.c

@@ -49,16 +49,6 @@ static int _adc_configure(Adc *dev, adc_res_t res);
 
 static mutex_t _lock = MUTEX_INIT;
 
-static inline void _prep(void)
-{
-    mutex_lock(&_lock);
-}
-
-static inline void _done(void)
-{
-    mutex_unlock(&_lock);
-}
-
 static inline void _wait_syncbusy(Adc *dev)
 {
 #ifdef ADC_STATUS_SYNCBUSY
@@ -263,7 +253,7 @@ int adc_init(adc_t line)
     const uint8_t adc = 0;
 #endif
 
-    _prep();
+    mutex_lock(&_lock);
 
     uint8_t muxpos = (adc_channels[line].inputctrl & ADC_INPUTCTRL_MUXPOS_Msk)
                    >> ADC_INPUTCTRL_MUXPOS_Pos;
@@ -284,34 +274,44 @@ int adc_init(adc_t line)
         gpio_init_mux(sam0_adc_pins[adc][muxneg], GPIO_MUX_B);
     }
 
-    _done();
+     mutex_unlock(&_lock);
 
     return 0;
 }
 
-int32_t adc_sample(adc_t line, adc_res_t res)
+static Adc *_dev(adc_t line)
 {
-    if (line >= ADC_NUMOF) {
-        DEBUG("adc: line arg not applicable\n");
-        return -1;
-    }
-
     /* The SAMD5x/SAME5x family has two ADCs: ADC0 and ADC1. */
 #ifdef ADC0
-    Adc *dev = adc_channels[line].dev;
+    return adc_channels[line].dev;
 #else
-    Adc *dev = ADC;
+    (void)line;
+    return ADC;
 #endif
+}
 
-    bool diffmode = adc_channels[line].inputctrl & ADC_INPUTCTRL_DIFFMODE;
+static Adc *_adc(uint8_t dev)
-
+{
-    _prep();
+    /* The SAMD5x/SAME5x family has two ADCs: ADC0 and ADC1. */
-
+#ifdef ADC0
-    if (_adc_configure(dev, res) != 0) {
+    switch (dev) {
-        _done();
+    case 0:
-        DEBUG("adc: configuration failed\n");
+        return ADC0;
-        return -1;
+    case 1:
+        return ADC1;
+    default:
+        return NULL;
     }
+#else
+    (void)dev;
+    return ADC;
+#endif
+}
+
+static int32_t _sample(adc_t line)
+{
+    Adc *dev = _dev(line);
+    bool diffmode = adc_channels[line].inputctrl & ADC_INPUTCTRL_DIFFMODE;
 
     dev->INPUTCTRL.reg = ADC_GAIN_FACTOR_DEFAULT
                        | adc_channels[line].inputctrl
@@ -319,7 +319,6 @@ int32_t adc_sample(adc_t line, adc_res_t res)
 #ifdef ADC_CTRLB_DIFFMODE
     dev->CTRLB.bit.DIFFMODE = diffmode;
 #endif
-
     _wait_syncbusy(dev);
 
     /* Start the conversion */
@@ -331,9 +330,6 @@ int32_t adc_sample(adc_t line, adc_res_t res)
     uint16_t sample = dev->RESULT.reg;
     int result;
 
-    _adc_poweroff(dev);
-    _done();
-
     /* in differential mode we lose one bit for the sign */
     if (diffmode) {
         result = 2 * (int16_t)sample;
@@ -341,11 +337,102 @@ int32_t adc_sample(adc_t line, adc_res_t res)
         result = sample;
     }
 
+    return result;
+}
+
+static uint8_t _shift_from_res(adc_res_t res)
+{
     /* 16 bit mode is implemented as oversampling */
     if ((res & 0x3) == 1) {
         /* ADC does automatic right shifts beyond 16 samples */
-        result <<= (4 - MIN(4, res >> 2));
+        return 4 - MIN(4, res >> 2);
+    }
+    return 0;
+}
+
+static void _get_adcs(bool *adc0, bool *adc1)
+{
+#ifndef ADC1
+    *adc0 = true;
+    *adc1 = false;
+    return;
+#else
+    for (unsigned i = 0; i < ADC_NUMOF; ++i) {
+        if (adc_channels[i].dev == ADC0) {
+            *adc0 = true;
+        } else if (adc_channels[i].dev == ADC1) {
+            *adc1 = true;
+        }
+    }
+#endif
+}
+
+static uint8_t _shift;
+void adc_continuous_begin(adc_res_t res)
+{
+    bool adc0, adc1;
+    _get_adcs(&adc0, &adc1);
+
+    mutex_lock(&_lock);
+
+    if (adc0) {
+        _adc_configure(_adc(0), res);
+    }
+    if (adc1) {
+        _adc_configure(_adc(1), res);
     }
 
-    return result;
+    _shift = _shift_from_res(res);
+}
+
+int32_t adc_continuous_sample(adc_t line)
+{
+    int val;
+    assert(line < ADC_NUMOF);
+
+    mutex_lock(&_lock);
+    val = _sample(line) << _shift;
+    mutex_unlock(&_lock);
+
+    return val;
+}
+
+void adc_continuous_stop(void)
+{
+    bool adc0, adc1;
+    _get_adcs(&adc0, &adc1);
+
+    if (adc0) {
+        _adc_poweroff(_adc(0));
+    }
+    if (adc1) {
+        _adc_poweroff(_adc(1));
+    }
+
+    mutex_unlock(&_lock);
+}
+
+int32_t adc_sample(adc_t line, adc_res_t res)
+{
+    if (line >= ADC_NUMOF) {
+        DEBUG("adc: line arg not applicable\n");
+        return -1;
+    }
+
+    mutex_lock(&_lock);
+
+    Adc *dev = _dev(line);
+
+    if (_adc_configure(dev, res) != 0) {
+        DEBUG("adc: configuration failed\n");
+        mutex_unlock(&_lock);
+        return -1;
+    }
+
+    int val = _sample(line) << _shift_from_res(res);
+
+    _adc_poweroff(dev);
+    mutex_unlock(&_lock);
+
+    return val;
 }