cpu/kinetis: optimization of DAC driver impl.

- use assert() for checking the line parameter
- use 'bit.h' for bitbanding
- simplified code a bit
- unified style of defifining the board configuration
- removed unused configurations form pba-d-01-kw2x and frdm-k64f

boards/frdm-k22f/include/periph_conf.h

@@ -120,14 +120,6 @@ static const adc_conf_t adc_config[] = {
 #define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
 /** @} */
 
-/**
- * @name DAC configuration
- * @{
- */
-#define DAC_CONFIG {}
-#define DAC_NUMOF  0
-/** @} */
-
 /**
  * @name    PWM configuration
  * @{

boards/frdm-k64f/include/periph_conf.h

@@ -114,14 +114,6 @@ static const adc_conf_t adc_config[] = {
 #define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
 /** @} */
 
-/**
- * @name DAC configuration
- * @{
- */
-#define DAC_CONFIG {}
-#define DAC_NUMOF  0
-/** @} */
-
 /**
  * @name    PWM configuration
  * @{

boards/mulle/include/periph_conf.h

@@ -172,15 +172,18 @@ static const adc_conf_t adc_config[] = {
 /** @} */
 
 /**
- * @name DAC configuration
+ * @name    DAC configuration
  * @{
  */
+static const dac_conf_t dac_config[] = {
+    {
+        .dev       = DAC0,
+        .scgc_addr = &SIM->SCGC2,
+        .scgc_bit  = SIM_SCGC2_DAC0_SHIFT
+    }
+};
 
-#define DAC_CONFIG { \
+#define DAC_NUMOF           (sizeof(dac_config) / sizeof(dac_config[0]))
-    { DAC0, (uint32_t volatile *)BITBAND_REGADDR(SIM->SCGC2, SIM_SCGC2_DAC0_SHIFT) }, \
-  }
-#define DAC_NUMOF 1
-
 /** @} */
 
 /**

boards/pba-d-01-kw2x/include/periph_conf.h

@@ -129,14 +129,6 @@ static const adc_conf_t adc_config[] = {
 #define ADC_NUMOF           (sizeof(adc_config) / sizeof(adc_config[0]))
 /** @} */
 
-/**
- * @name DAC configuration
- * @{
- */
-#define DAC_CONFIG {}
-#define DAC_NUMOF  0
-/** @} */
-
 /**
  * @name    PWM configuration
  * @{

cpu/kinetis_common/include/periph_cpu.h

@@ -239,10 +239,9 @@ typedef struct {
  * @brief   CPU specific DAC configuration
  */
 typedef struct {
-    /** DAC device base pointer */
+    DAC_Type *dev;                  /**< DAC device base pointer */
-    DAC_Type *dev;
+    volatile uint32_t *scgc_addr;   /**< Clock enable register, in SIM module */
-    /** Pointer to module clock gate bit in bitband region, use BITBAND_REGADDR() */
+    uint8_t scgc_bit;               /**< Clock enable bit, within the register */
-    uint32_t volatile *clk_gate;
 } dac_conf_t;
 
 /**

cpu/kinetis_common/periph/dac.c

@@ -27,79 +27,62 @@
 
 #include "cpu.h"
 #include "bit.h"
+#include "assert.h"
 #include "periph/dac.h"
 #include "periph_conf.h"
 
-static const dac_conf_t dac_config[] = DAC_CONFIG;
+/* only compile this file if there are DAC lines defined */
+#ifdef DAC_NUMOF
+
+static inline DAC_Type *dev(dac_t line)
+{
+    return dac_config[line].dev;
+}
 
 int8_t dac_init(dac_t line)
 {
-    DAC_Type *dac;
+    if (line >= DAC_NUMOF) {
-    if ((unsigned int)line >= DAC_NUMOF) {
         return DAC_NOLINE;
     }
 
-    dac = dac_config[line].dev;
-
     /* Enable module clock */
-    *(dac_config[line].clk_gate) = 1;
+    bit_set32(dac_config[line].scgc_addr, dac_config[line].scgc_bit);
-
     /* Select VDDA as voltage reference */
-    dac->C0 = (DAC_C0_DACRFS_MASK);
+    dev(line)->C0 = (DAC_C0_DACRFS_MASK);
-
     /* Disable DMA and buffering */
-    dac->C1 = 0;
+    dev(line)->C1 = 0;
-    dac->C2 = 0;
+    dev(line)->C2 = 0;
-
+    /* Enable the device */
-    /* Power on */
+    bit_set8(&dac_config[line].dev->C0, DAC_C0_DACEN_SHIFT);
-    dac_poweron(line);
-
     /* Set output value to zero */
     dac_set(line, 0);
+
     return DAC_OK;
 }
 
 void dac_set(dac_t line, uint16_t value)
 {
-    DAC_Type *dac;
+    assert(line < DAC_NUMOF);
-
-    if ((unsigned int)line >= DAC_NUMOF) {
-        return;
-    }
-
-    dac = dac_config[line].dev;
 
     /* Scale to 12 bit */
-    value = value >> ((sizeof(value) * 8) - 12);
+    value = (value >> 4);
 
-    dac->DAT[0].DATH = ((value >> 8) & 0xff);
+    dev(line)->DAT[0].DATH = ((value >> 8) & 0xff);
-    dac->DAT[0].DATL = (value & 0xff);
+    dev(line)->DAT[0].DATL = (value & 0xff);
-}
-
-static inline void _dac_set_power(dac_t line, uint8_t value)
-{
-    DAC_Type *dac;
-
-    if ((unsigned int)line >= DAC_NUMOF) {
-        return;
-    }
-
-    dac = dac_config[line].dev;
-
-    if (value) {
-        bit_set8(&dac->C0, DAC_C0_DACEN_SHIFT);
-    }
-    else {
-        bit_clear8(&dac->C0, DAC_C0_DACEN_SHIFT);
-    }
 }
 
 void dac_poweron(dac_t line)
 {
-    _dac_set_power(line, 1);
+    assert(line < DAC_NUMOF);
+
+    bit_set8(&dac_config[line].dev->C0, DAC_C0_DACEN_SHIFT);
 }
 
 void dac_poweroff(dac_t line)
 {
-    _dac_set_power(line, 0);
+    assert(line < DAC_NUMOF);
+
+    bit_clear8(&dac_config[line].dev->C0, DAC_C0_DACEN_SHIFT);
 }
+
+#endif /* DAC_NUMOF */