Resurrect ADC support.

Standard refactoring: add series headers for F1 and F2, along with
series adc.c files. There are some issues relating to adc_extsel_event
to hammer out later, but this will do for now.

We also add some new portability interfaces to libmaple/adc.h in order
for Wirish to use the same code to initialize the ADCs at init() time.

As usual, F1 is untested.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

3 files changed, 416 insertions, 0 deletions

diff --git a/libmaple/stm32f2/adc.c b/libmaple/stm32f2/adc.c
new file mode 100644
index 0000000..fbe1618
--- /dev/null
+++ b/libmaple/stm32f2/adc.c
@@ -0,0 +1,84 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2012 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file libmaple/stm32f2/include/series/adc.c
+ * @brief STM32F2 ADC header.
+ */
+
+#include <libmaple/adc.h>
+#include <libmaple/gpio.h>
+
+/*
+ * Devices
+ */
+
+static adc_dev adc1 = {
+    .regs   = ADC1_BASE,
+    .clk_id = RCC_ADC1,
+};
+/** ADC1 device. */
+const adc_dev *ADC1 = &adc1;
+
+static adc_dev adc2 = {
+    .regs   = ADC2_BASE,
+    .clk_id = RCC_ADC2,
+};
+/** ADC2 device. */
+const adc_dev *ADC2 = &adc2;
+
+adc_dev adc3 = {
+    .regs   = ADC3_BASE,
+    .clk_id = RCC_ADC3,
+};
+/** ADC3 device. */
+const adc_dev *ADC3 = &adc3;
+
+/*
+ * Common routines
+ */
+
+void adc_set_prescaler(adc_prescaler pre) {
+    uint32 ccr = ADC_COMMON_BASE->CCR;
+    ccr &= ~ADC_CCR_ADCPRE;
+    ccr |= (uint32)pre;
+    ADC_COMMON_BASE->CCR = ccr;
+}
+
+void adc_foreach(void (*fn)(const adc_dev*)) {
+    fn(ADC1);
+    fn(ADC2);
+    fn(ADC3);
+}
+
+void adc_gpio_cfg(gpio_dev *gdev, uint8 bit) {
+    gpio_set_modef(gdev, bit, GPIO_MODE_ANALOG, GPIO_MODEF_PUPD_NONE);
+}
+
+void adc_enable_single_swstart(const adc_dev *dev) {
+    adc_init(dev);
+    adc_enable(dev);
+}
diff --git a/libmaple/stm32f2/include/series/adc.h b/libmaple/stm32f2/include/series/adc.h
new file mode 100644
index 0000000..4f0cd6b
--- /dev/null
+++ b/libmaple/stm32f2/include/series/adc.h
@@ -0,0 +1,331 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2012 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file stm32f2/include/series/adc.h
+ * @author Marti Bolivar <mbolivar@leaflabs.com>,
+ * @brief STM32F2 ADC header.
+ */
+
+#ifndef _LIBMAPLE_STM32F2_ADC_H_
+#define _LIBMAPLE_STM32F2_ADC_H_
+
+#include <libmaple/libmaple_types.h>
+
+/*
+ * Devices
+ */
+
+extern const struct adc_dev *ADC1;
+extern const struct adc_dev *ADC2;
+extern const struct adc_dev *ADC3;
+
+/*
+ * Common register map
+ */
+
+/** ADC common register map type */
+typedef struct adc_common_reg_map {
+    __io uint32 CSR;            /**< Common status register */
+    __io uint32 CCR;            /**< Common control register */
+    __io uint32 CDR;            /**<
+                                 * @brief Common regular data register
+                                 *        for dual and triple modes */
+} adc_common_reg_map;
+
+/*
+ * Register map base pointers
+ */
+
+/** ADC1 register map base pointer. */
+#define ADC1_BASE       ((struct adc_reg_map*)0x40012000)
+/** ADC2 register map base pointer. */
+#define ADC2_BASE       ((struct adc_reg_map*)0x40012100)
+/** ADC3 register map base pointer. */
+#define ADC3_BASE       ((struct adc_reg_map*)0x40012200)
+/** ADC common register map base pointer. */
+#define ADC_COMMON_BASE ((struct adc_common_reg_map*)0x40012300)
+
+/*
+ * Register bit definitions
+ */
+
+/* Status register */
+
+/** Overrun bit. */
+#define ADC_SR_OVR_BIT                  5
+/** Overrun. */
+#define ADC_SR_OVR                      (1U << ADC_SR_OVR_BIT)
+
+/* Control register 1 */
+
+/** Overrun interrupt enable bit. */
+#define ADC_CR1_OVRIE_BIT               26
+
+/** Overrun interrupt error enable. */
+#define ADC_CR1_OVRIE                   (1U << ADC_CR1_OVRIE_BIT)
+/** Conversion resolution. */
+#define ADC_CR1_RES                     (0x3U << 24)
+/** Conversion resolution: 12 bit (at least 15 ADCCLK cycles). */
+#define ADC_CR1_RES_12BIT               (0x0U << 24)
+/** Conversion resolution: 10 bit (at least 13 ADCCLK cycles). */
+#define ADC_CR1_RES_10BIT               (0x1U << 24)
+/** Conversion resolution: 8 bit (at least 11 ADCCLK cycles). */
+#define ADC_CR1_RES_8BIT                (0x2U << 24)
+/** Conversion resolution: 6 bit (at least 9 ADCCLK cycles). */
+#define ADC_CR1_RES_6BIT                (0x3U << 24)
+
+/* Control register 2 */
+
+#define ADC_CR2_SWSTART_BIT             30
+#define ADC_CR2_JSWSTART_BIT            22
+#define ADC_CR2_ALIGN_BIT               11
+#define ADC_CR2_EOCS_BIT                10
+#define ADC_CR2_DDS_BIT                 9
+#define ADC_CR2_DMA_BIT                 8
+#define ADC_CR2_CONT_BIT                1
+#define ADC_CR2_ADON_BIT                0
+
+#define ADC_CR2_SWSTART                 (1U << ADC_CR2_SWSTART_BIT)
+#define ADC_CR2_EXTEN                   (0x3 << 28)
+#define ADC_CR2_EXTEN_DISABLED          (0x0 << 28)
+#define ADC_CR2_EXTEN_RISE              (0x1 << 28)
+#define ADC_CR2_EXTEN_FALL              (0x2 << 28)
+#define ADC_CR2_EXTEN_RISE_FALL         (0x3 << 28)
+#define ADC_CR2_EXTSEL                  (0xF << 24)
+#define ADC_CR2_EXTSEL_TIM1_CC1         (0x0 << 24)
+#define ADC_CR2_EXTSEL_TIM1_CC2         (0x1 << 24)
+#define ADC_CR2_EXTSEL_TIM1_CC3         (0x2 << 24)
+#define ADC_CR2_EXTSEL_TIM2_CC2         (0x3 << 24)
+#define ADC_CR2_EXTSEL_TIM2_CC3         (0x4 << 24)
+#define ADC_CR2_EXTSEL_TIM2_CC4         (0x5 << 24)
+#define ADC_CR2_EXTSEL_TIM1_TRGO        (0x6 << 24)
+#define ADC_CR2_EXTSEL_TIM3_CC1         (0x7 << 24)
+#define ADC_CR2_EXTSEL_TIM3_TRGO        (0x8 << 24)
+#define ADC_CR2_EXTSEL_TIM4_CC4         (0x9 << 24)
+#define ADC_CR2_EXTSEL_TIM5_CC1         (0xA << 24)
+#define ADC_CR2_EXTSEL_TIM5_CC2         (0xB << 24)
+#define ADC_CR2_EXTSEL_TIM5_CC3         (0xC << 24)
+#define ADC_CR2_EXTSEL_TIM8_CC1         (0xD << 24)
+#define ADC_CR2_EXTSEL_TIM8_TRGO        (0xE << 24)
+#define ADC_CR2_EXTSEL_TIM1_EXTI11      (0xF << 24)
+#define ADC_CR2_JSWSTART                (1U << ADC_CR2_JSWSTART_BIT)
+#define ADC_CR2_JEXTEN                  (0x3 << 20)
+#define ADC_CR2_JEXTEN_DISABLED         (0x0 << 20)
+#define ADC_CR2_JEXTEN_RISE             (0x1 << 20)
+#define ADC_CR2_JEXTEN_FALL             (0x2 << 20)
+#define ADC_CR2_JEXTEN_RISE_FALL        (0x3 << 20)
+#define ADC_CR2_JEXTSEL                 (0xF << 16)
+#define ADC_CR2_JEXTSEL_TIM1_CC4        (0x0 << 16)
+#define ADC_CR2_JEXTSEL_TIM1_TRGO       (0x1 << 16)
+#define ADC_CR2_JEXTSEL_TIM2_CC1        (0x2 << 16)
+#define ADC_CR2_JEXTSEL_TIM2_TRGO       (0x3 << 16)
+#define ADC_CR2_JEXTSEL_TIM3_CC2        (0x4 << 16)
+#define ADC_CR2_JEXTSEL_TIM3_CC4        (0x5 << 16)
+#define ADC_CR2_JEXTSEL_TIM4_CC1        (0x6 << 16)
+#define ADC_CR2_JEXTSEL_TIM4_CC2        (0x7 << 16)
+#define ADC_CR2_JEXTSEL_TIM4_CC3        (0x8 << 16)
+#define ADC_CR2_JEXTSEL_TIM4_TRGO       (0x9 << 16)
+#define ADC_CR2_JEXTSEL_TIM5_CC4        (0xA << 16)
+#define ADC_CR2_JEXTSEL_TIM5_TRGO       (0xB << 16)
+#define ADC_CR2_JEXTSEL_TIM8_CC2        (0xC << 16)
+#define ADC_CR2_JEXTSEL_TIM8_CC3        (0xD << 16)
+#define ADC_CR2_JEXTSEL_TIM8_CC4        (0xE << 16)
+#define ADC_CR2_JEXTSEL_TIM1_EXTI15     (0xF << 16)
+#define ADC_CR2_ALIGN                   (1U << ADC_CR2_ALIGN_BIT)
+#define ADC_CR2_ALIGN_RIGHT             (0U << ADC_CR2_ALIGN_BIT)
+#define ADC_CR2_ALIGN_LEFT              (1U << ADC_CR2_ALIGN_BIT)
+#define ADC_CR2_EOCS                    (1U << ADC_CR2_EOCS_BIT)
+#define ADC_CR2_EOCS_SEQUENCE           (0U << ADC_CR2_EOCS_BIT)
+#define ADC_CR2_EOCS_CONVERSION         (1U << ADC_CR2_EOCS_BIT)
+#define ADC_CR2_DDS                     (1U << ADC_CR2_DDS_BIT)
+#define ADC_CR2_DMA                     (1U << ADC_CR2_DMA_BIT)
+#define ADC_CR2_CONT                    (1U << ADC_CR2_CONT_BIT)
+#define ADC_CR2_ADON                    (1U << ADC_CR2_ADON_BIT)
+
+/* Common status register */
+
+#define ADC_CSR_OVR3_BIT                21
+#define ADC_CSR_STRT3_BIT               20
+#define ADC_CSR_JSTRT3_BIT              19
+#define ADC_CSR_JEOC3_BIT               18
+#define ADC_CSR_EOC3_BIT                17
+#define ADC_CSR_AWD3_BIT                16
+#define ADC_CSR_OVR2_BIT                13
+#define ADC_CSR_STRT2_BIT               12
+#define ADC_CSR_JSTRT2_BIT              11
+#define ADC_CSR_JEOC2_BIT               10
+#define ADC_CSR_EOC2_BIT                9
+#define ADC_CSR_AWD2_BIT                8
+#define ADC_CSR_OVR1_BIT                5
+#define ADC_CSR_STRT1_BIT               4
+#define ADC_CSR_JSTRT1_BIT              3
+#define ADC_CSR_JEOC1_BIT               2
+#define ADC_CSR_EOC1_BIT                1
+#define ADC_CSR_AWD1_BIT                0
+
+#define ADC_CSR_OVR3                    (1U << ADC_CSR_OVR3_BIT)
+#define ADC_CSR_STRT3                   (1U << ADC_CSR_STRT3_BIT)
+#define ADC_CSR_JSTRT3                  (1U << ADC_CSR_JSTRT3_BIT)
+#define ADC_CSR_JEOC3                   (1U << ADC_CSR_JEOC3_BIT)
+#define ADC_CSR_EOC3                    (1U << ADC_CSR_EOC3_BIT)
+#define ADC_CSR_AWD3                    (1U << ADC_CSR_AWD3_BIT)
+#define ADC_CSR_OVR2                    (1U << ADC_CSR_OVR2_BIT)
+#define ADC_CSR_STRT2                   (1U << ADC_CSR_STRT2_BIT)
+#define ADC_CSR_JSTRT2                  (1U << ADC_CSR_JSTRT2_BIT)
+#define ADC_CSR_JEOC2                   (1U << ADC_CSR_JEOC2_BIT)
+#define ADC_CSR_EOC2                    (1U << ADC_CSR_EOC2_BIT)
+#define ADC_CSR_AWD2                    (1U << ADC_CSR_AWD2_BIT)
+#define ADC_CSR_OVR1                    (1U << ADC_CSR_OVR1_BIT)
+#define ADC_CSR_STRT1                   (1U << ADC_CSR_STRT1_BIT)
+#define ADC_CSR_JSTRT1                  (1U << ADC_CSR_JSTRT1_BIT)
+#define ADC_CSR_JEOC1                   (1U << ADC_CSR_JEOC1_BIT)
+#define ADC_CSR_EOC1                    (1U << ADC_CSR_EOC1_BIT)
+#define ADC_CSR_AWD1                    (1U << ADC_CSR_AWD1_BIT)
+
+/* Common control register */
+
+#define ADC_CCR_TSVREFE_BIT             23
+#define ADC_CCR_VBATE_BIT               22
+#define ADC_CCR_DDS_BIT                 13
+
+#define ADC_CCR_TSVREFE                       (1U << ADC_CCR_TSVREFE_BIT)
+#define ADC_CCR_VBATE                         (1U << ADC_CCR_VBATE_BIT)
+#define ADC_CCR_ADCPRE                        (0x3 << 16)
+#define ADC_CCR_ADCPRE_PCLK2_DIV_2            (0x0 << 16)
+#define ADC_CCR_ADCPRE_PCLK2_DIV_4            (0x1 << 16)
+#define ADC_CCR_ADCPRE_PCLK2_DIV_6            (0x2 << 16)
+#define ADC_CCR_ADCPRE_PCLK2_DIV_8            (0x3 << 16)
+#define ADC_CCR_DMA                           (0x3 << 14)
+#define ADC_CCR_DMA_DIS                       (0x0 << 14)
+#define ADC_CCR_DMA_MODE_1                    (0x1 << 14)
+#define ADC_CCR_DMA_MODE_2                    (0x2 << 14)
+#define ADC_CCR_DMA_MODE_3                    (0x3 << 14)
+#define ADC_CCR_DDS                           (1U << ADC_CCR_DDS_BIT)
+#define ADC_CCR_DELAY                         (0xF << 8)
+#define ADC_CCR_DELAY_5                       (0x0 << 8)
+#define ADC_CCR_DELAY_6                       (0x1 << 8)
+#define ADC_CCR_DELAY_7                       (0x2 << 8)
+#define ADC_CCR_DELAY_8                       (0x3 << 8)
+#define ADC_CCR_DELAY_9                       (0x4 << 8)
+#define ADC_CCR_DELAY_10                      (0x5 << 8)
+#define ADC_CCR_DELAY_11                      (0x6 << 8)
+#define ADC_CCR_DELAY_12                      (0x7 << 8)
+#define ADC_CCR_DELAY_13                      (0x8 << 8)
+#define ADC_CCR_DELAY_14                      (0x9 << 8)
+#define ADC_CCR_DELAY_15                      (0xA << 8)
+#define ADC_CCR_DELAY_16                      (0xB << 8)
+#define ADC_CCR_DELAY_17                      (0xC << 8)
+#define ADC_CCR_DELAY_18                      (0xD << 8)
+#define ADC_CCR_DELAY_19                      (0xE << 8)
+#define ADC_CCR_DELAY_20                      (0xF << 8)
+/** Multi ADC mode selection. */
+#define ADC_CCR_MULTI                         0x1F
+/** All ADCs independent. */
+#define ADC_CCR_MULTI_INDEPENDENT             0x0
+/** Dual mode: combined regular simultaneous/injected simultaneous. */
+#define ADC_CCR_MULTI_DUAL_REG_SIM_INJ_SIM    0x1
+/** Dual mode: combined regular simultaneous/alternate trigger. */
+#define ADC_CCR_MULTI_DUAL_REG_SIM_ALT_TRIG   0x2
+/** Dual mode: injected simultaneous mode only. */
+#define ADC_CCR_MULTI_DUAL_INJ_SIM            0x5
+/** Dual mode: regular simultaneous mode only. */
+#define ADC_CCR_MULTI_DUAL_REG_SIM            0x6
+/** Dual mode: interleaved mode only. */
+#define ADC_CCR_MULTI_DUAL_INTER              0x7
+/** Dual mode: alternate trigger mode only. */
+#define ADC_CCR_MULTI_DUAL_ALT_TRIG           0x9
+/** Triple mode: combined regular simultaneous/injected simultaneous. */
+#define ADC_CCR_MULTI_TRIPLE_REG_SIM_INJ_SIM  0x10
+/** Triple mode: combined regular simultaneous/alternate trigger. */
+#define ADC_CCR_MULTI_TRIPLE_REG_SIM_ALT_TRIG 0x11
+/** Triple mode: injected simultaneous mode only. */
+#define ADC_CCR_MULTI_TRIPLE_INJ_SIM          0x12
+/** Triple mode: regular simultaneous mode only. */
+#define ADC_CCR_MULTI_TRIPLE_REG_SIM          0x15
+/** Triple mode: interleaved mode only. */
+#define ADC_CCR_MULTI_TRIPLE_INTER            0x17
+/** Triple mode: alternate trigger mode only. */
+#define ADC_CCR_MULTI_TRIPLE_ALT_TRIG         0x19
+
+/* Common regular data register for dual and triple modes */
+
+#define ADC_CDR_DATA2                   0xFFFF0000
+#define ADC_CDR_DATA1                   0xFFFF
+
+/*
+ * Other types
+ */
+
+/**
+ * @brief STM32F2 external event selectors for regular group
+ *        conversion.
+ * @see adc_set_extsel()
+ */
+typedef enum adc_extsel_event {
+    ADC_EXT_EV_TIM1_CC1    = ADC_CR2_EXTSEL_TIM1_CC1,
+    ADC_EXT_EV_TIM1_CC2    = ADC_CR2_EXTSEL_TIM1_CC2,
+    ADC_EXT_EV_TIM1_CC3    = ADC_CR2_EXTSEL_TIM1_CC3,
+    ADC_EXT_EV_TIM2_CC2    = ADC_CR2_EXTSEL_TIM2_CC2,
+    ADC_EXT_EV_TIM2_CC3    = ADC_CR2_EXTSEL_TIM2_CC3,
+    ADC_EXT_EV_TIM2_CC4    = ADC_CR2_EXTSEL_TIM2_CC4,
+    ADC_EXT_EV_TIM1_TRGO   = ADC_CR2_EXTSEL_TIM1_TRGO,
+    ADC_EXT_EV_TIM3_CC1    = ADC_CR2_EXTSEL_TIM3_CC1,
+    ADC_EXT_EV_TIM3_TRGO   = ADC_CR2_EXTSEL_TIM3_TRGO,
+    ADC_EXT_EV_TIM4_CC4    = ADC_CR2_EXTSEL_TIM4_CC4,
+    ADC_EXT_EV_TIM5_CC1    = ADC_CR2_EXTSEL_TIM5_CC1,
+    ADC_EXT_EV_TIM5_CC2    = ADC_CR2_EXTSEL_TIM5_CC2,
+    ADC_EXT_EV_TIM5_CC3    = ADC_CR2_EXTSEL_TIM5_CC3,
+    ADC_EXT_EV_TIM8_CC1    = ADC_CR2_EXTSEL_TIM8_CC1,
+    ADC_EXT_EV_TIM8_TRGO   = ADC_CR2_EXTSEL_TIM8_TRGO,
+    ADC_EXT_EV_TIM1_EXTI11 = ADC_CR2_EXTSEL_TIM1_EXTI11,
+} adc_extsel_event;
+
+/**
+ * @brief STM32F2 sample times, in ADC clock cycles.
+ */
+typedef enum adc_smp_rate {
+    ADC_SMPR_3,                 /**< 3 ADC cycles */
+    ADC_SMPR_15,                /**< 15 ADC cycles */
+    ADC_SMPR_28,                /**< 28 ADC cycles */
+    ADC_SMPR_56,                /**< 56 ADC cycles */
+    ADC_SMPR_84,                /**< 84 ADC cycles */
+    ADC_SMPR_112,               /**< 112 ADC cycles */
+    ADC_SMPR_144,               /**< 144 ADC cycles */
+    ADC_SMPR_480,               /**< 480 ADC cycles */
+} adc_smp_rate;
+
+/**
+ * @brief STM32F2 ADC prescalers, as divisors of PCLK2.
+ */
+typedef enum adc_prescaler {
+    ADC_PRE_PCLK2_DIV_2 = ADC_CCR_ADCPRE_PCLK2_DIV_2, /** PCLK2 divided by 2 */
+    ADC_PRE_PCLK2_DIV_4 = ADC_CCR_ADCPRE_PCLK2_DIV_4, /** PCLK2 divided by 4 */
+    ADC_PRE_PCLK2_DIV_6 = ADC_CCR_ADCPRE_PCLK2_DIV_6, /** PCLK2 divided by 6 */
+    ADC_PRE_PCLK2_DIV_8 = ADC_CCR_ADCPRE_PCLK2_DIV_8, /** PCLK2 divided by 8 */
+} adc_prescaler;
+
+#endif
diff --git a/libmaple/stm32f2/rules.mk b/libmaple/stm32f2/rules.mk
index a46f8d1..5951b94 100644
--- a/libmaple/stm32f2/rules.mk
+++ b/libmaple/stm32f2/rules.mk
@@ -11,6 +11,7 @@ CFLAGS_$(d) = -I$(d) $(LIBMAPLE_INCLUDES) $(LIBMAPLE_PRIVATE_INCLUDES) -Wall -We
 sSRCS_$(d) := isrs.S
 sSRCS_$(d) += vector_table.S
 
+cSRCS_$(d) := adc.c
 cSRCS_$(d) += fsmc.c
 cSRCS_$(d) += gpio.c
 cSRCS_$(d) += rcc.c