Move GPIO support for STM32F1 to libmaple/stm32f1.

Make a new family header, libmaple/stm32f1/include/family/gpio.h, and
supporting libmaple/stm32f1/gpio.c.

Beyond registers and devices, these also include anything mentioning
AFIO, which doesn't exist on F2.

Update libmaple/stm32f1/rules.mk for new gpio.c.

Alter gpio_write_bit() to use dev->regs->BSRR only. BRRs are not
present on STM32F2.

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

3 files changed, 664 insertions, 0 deletions

diff --git a/libmaple/stm32f1/gpio.c b/libmaple/stm32f1/gpio.c
new file mode 100644
index 0000000..01a4028
--- /dev/null
+++ b/libmaple/stm32f1/gpio.c
@@ -0,0 +1,184 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung.
+ *
+ * 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/stm32f1/gpio.c
+ * @brief GPIO support for STM32F1 line.
+ */
+
+#include <libmaple/gpio.h>
+#include <libmaple/rcc.h>
+
+/*
+ * GPIO devices
+ */
+
+gpio_dev gpioa = {
+    .regs      = GPIOA_BASE,
+    .clk_id    = RCC_GPIOA,
+    .exti_port = AFIO_EXTI_PA,
+};
+/** GPIO port A device. */
+gpio_dev* const GPIOA = &gpioa;
+
+gpio_dev gpiob = {
+    .regs      = GPIOB_BASE,
+    .clk_id    = RCC_GPIOB,
+    .exti_port = AFIO_EXTI_PB,
+};
+/** GPIO port B device. */
+gpio_dev* const GPIOB = &gpiob;
+
+gpio_dev gpioc = {
+    .regs      = GPIOC_BASE,
+    .clk_id    = RCC_GPIOC,
+    .exti_port = AFIO_EXTI_PC,
+};
+/** GPIO port C device. */
+gpio_dev* const GPIOC = &gpioc;
+
+gpio_dev gpiod = {
+    .regs      = GPIOD_BASE,
+    .clk_id    = RCC_GPIOD,
+    .exti_port = AFIO_EXTI_PD,
+};
+/** GPIO port D device. */
+gpio_dev* const GPIOD = &gpiod;
+
+#ifdef STM32_HIGH_DENSITY
+gpio_dev gpioe = {
+    .regs      = GPIOE_BASE,
+    .clk_id    = RCC_GPIOE,
+    .exti_port = AFIO_EXTI_PE,
+};
+/** GPIO port E device. */
+gpio_dev* const GPIOE = &gpioe;
+
+gpio_dev gpiof = {
+    .regs      = GPIOF_BASE,
+    .clk_id    = RCC_GPIOF,
+    .exti_port = AFIO_EXTI_PF,
+};
+/** GPIO port F device. */
+gpio_dev* const GPIOF = &gpiof;
+
+gpio_dev gpiog = {
+    .regs      = GPIOG_BASE,
+    .clk_id    = RCC_GPIOG,
+    .exti_port = AFIO_EXTI_PG,
+};
+/** GPIO port G device. */
+gpio_dev* const GPIOG = &gpiog;
+#endif
+
+/*
+ * GPIO routines
+ */
+
+/**
+ * Initialize and reset all available GPIO devices.
+ */
+void gpio_init_all(void) {
+    gpio_init(GPIOA);
+    gpio_init(GPIOB);
+    gpio_init(GPIOC);
+    gpio_init(GPIOD);
+#ifdef STM32_HIGH_DENSITY
+    gpio_init(GPIOE);
+    gpio_init(GPIOF);
+    gpio_init(GPIOG);
+#endif
+}
+
+/**
+ * Set the mode of a GPIO pin.
+ *
+ * @param dev GPIO device.
+ * @param pin Pin on the device whose mode to set, 0--15.
+ * @param mode General purpose or alternate function mode to set the pin to.
+ * @see gpio_pin_mode
+ */
+void gpio_set_mode(gpio_dev *dev, uint8 pin, gpio_pin_mode mode) {
+    gpio_reg_map *regs = dev->regs;
+    __io uint32 *cr = &regs->CRL + (pin >> 3);
+    uint32 shift = (pin & 0x7) * 4;
+    uint32 tmp = *cr;
+
+    tmp &= ~(0xF << shift);
+    tmp |= (mode == GPIO_INPUT_PU ? GPIO_INPUT_PD : mode) << shift;
+    *cr = tmp;
+
+    if (mode == GPIO_INPUT_PD) {
+        regs->ODR &= ~BIT(pin);
+    } else if (mode == GPIO_INPUT_PU) {
+        regs->ODR |= BIT(pin);
+    }
+}
+
+/*
+ * AFIO
+ */
+
+/**
+ * @brief Initialize the AFIO clock, and reset the AFIO registers.
+ */
+void afio_init(void) {
+    rcc_clk_enable(RCC_AFIO);
+    rcc_reset_dev(RCC_AFIO);
+}
+
+#define AFIO_EXTI_SEL_MASK 0xF
+
+/**
+ * @brief Select a source input for an external interrupt.
+ *
+ * @param exti      External interrupt.
+ * @param gpio_port Port which contains pin to use as source input.
+ * @see afio_exti_num
+ * @see afio_exti_port
+ */
+void afio_exti_select(afio_exti_num exti, afio_exti_port gpio_port) {
+    __io uint32 *exti_cr = &AFIO_BASE->EXTICR1 + exti / 4;
+    uint32 shift = 4 * (exti % 4);
+    uint32 cr = *exti_cr;
+
+    cr &= ~(AFIO_EXTI_SEL_MASK << shift);
+    cr |= gpio_port << shift;
+    *exti_cr = cr;
+}
+
+/**
+ * @brief Perform an alternate function remap.
+ * @param remapping Remapping to perform.
+ */
+void afio_remap(afio_remap_peripheral remapping) {
+    if (remapping & AFIO_REMAP_USE_MAPR2) {
+        remapping &= ~AFIO_REMAP_USE_MAPR2;
+        AFIO_BASE->MAPR2 |= remapping;
+    } else {
+        AFIO_BASE->MAPR |= remapping;
+    }
+}
diff --git a/libmaple/stm32f1/include/family/gpio.h b/libmaple/stm32f1/include/family/gpio.h
new file mode 100644
index 0000000..c10244d
--- /dev/null
+++ b/libmaple/stm32f1/include/family/gpio.h
@@ -0,0 +1,479 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung.
+ * Copyright (c) 2011 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/stm32f1/gpio.h
+ *  @brief General purpose I/O (GPIO) and Alternate Function I/O
+ *         (AFIO) prototypes, defines, and inlined access functions.
+ */
+
+#ifndef _LIBMAPLE_STM32F1_GPIO_H_
+#define _LIBMAPLE_STM32F1_GPIO_H_
+
+#ifdef __cplusplus
+extern "C"{
+#endif
+
+#include <libmaple/libmaple.h>
+#include <libmaple/rcc.h>
+
+/*
+ * GPIO register maps and devices
+ */
+
+/** GPIO register map type */
+typedef struct gpio_reg_map {
+    __io uint32 CRL;      /**< Port configuration register low */
+    __io uint32 CRH;      /**< Port configuration register high */
+    __io uint32 IDR;      /**< Port input data register */
+    __io uint32 ODR;      /**< Port output data register */
+    __io uint32 BSRR;     /**< Port bit set/reset register */
+    __io uint32 BRR;      /**< Port bit reset register */
+    __io uint32 LCKR;     /**< Port configuration lock register */
+} gpio_reg_map;
+
+/**
+ * @brief External interrupt line port selector.
+ *
+ * Used to determine which GPIO port to map an external interrupt line
+ * onto. */
+/* (See AFIO sections, below) */
+typedef enum afio_exti_port {
+    AFIO_EXTI_PA,               /**< Use port A (PAx) pin. */
+    AFIO_EXTI_PB,               /**< Use port B (PBx) pin. */
+    AFIO_EXTI_PC,               /**< Use port C (PCx) pin. */
+    AFIO_EXTI_PD,               /**< Use port D (PDx) pin. */
+#ifdef STM32_HIGH_DENSITY
+    AFIO_EXTI_PE,               /**< Use port E (PEx) pin. */
+    AFIO_EXTI_PF,               /**< Use port F (PFx) pin. */
+    AFIO_EXTI_PG,               /**< Use port G (PGx) pin. */
+#endif
+} afio_exti_port;
+
+/** GPIO device type */
+typedef struct gpio_dev {
+    gpio_reg_map *regs;       /**< Register map */
+    rcc_clk_id clk_id;        /**< RCC clock information */
+    afio_exti_port exti_port; /**< AFIO external interrupt port value */
+} gpio_dev;
+
+extern gpio_dev gpioa;
+extern gpio_dev* const GPIOA;
+extern gpio_dev gpiob;
+extern gpio_dev* const GPIOB;
+extern gpio_dev gpioc;
+extern gpio_dev* const GPIOC;
+extern gpio_dev gpiod;
+extern gpio_dev* const GPIOD;
+#ifdef STM32_HIGH_DENSITY
+extern gpio_dev gpioe;
+extern gpio_dev* const GPIOE;
+extern gpio_dev gpiof;
+extern gpio_dev* const GPIOF;
+extern gpio_dev gpiog;
+extern gpio_dev* const GPIOG;
+#endif
+
+/** GPIO port A register map base pointer */
+#define GPIOA_BASE                      ((struct gpio_reg_map*)0x40010800)
+/** GPIO port B register map base pointer */
+#define GPIOB_BASE                      ((struct gpio_reg_map*)0x40010C00)
+/** GPIO port C register map base pointer */
+#define GPIOC_BASE                      ((struct gpio_reg_map*)0x40011000)
+/** GPIO port D register map base pointer */
+#define GPIOD_BASE                      ((struct gpio_reg_map*)0x40011400)
+#ifdef STM32_HIGH_DENSITY
+/** GPIO port E register map base pointer */
+#define GPIOE_BASE                      ((struct gpio_reg_map*)0x40011800)
+/** GPIO port F register map base pointer */
+#define GPIOF_BASE                      ((struct gpio_reg_map*)0x40011C00)
+/** GPIO port G register map base pointer */
+#define GPIOG_BASE                      ((struct gpio_reg_map*)0x40012000)
+#endif
+
+/*
+ * GPIO register bit definitions
+ */
+
+/* Control registers, low and high */
+
+#define GPIO_CR_CNF                     (0x3 << 2)
+#define GPIO_CR_CNF_INPUT_ANALOG        (0x0 << 2)
+#define GPIO_CR_CNF_INPUT_FLOATING      (0x1 << 2)
+#define GPIO_CR_CNF_INPUT_PU_PD         (0x2 << 2)
+#define GPIO_CR_CNF_OUTPUT_PP           (0x0 << 2)
+#define GPIO_CR_CNF_OUTPUT_OD           (0x1 << 2)
+#define GPIO_CR_CNF_AF_OUTPUT_PP        (0x2 << 2)
+#define GPIO_CR_CNF_AF_OUTPUT_OD        (0x3 << 2)
+#define GPIO_CR_MODE                    0x3
+#define GPIO_CR_MODE_INPUT              0x0
+#define GPIO_CR_MODE_OUTPUT_10MHZ       0x1
+#define GPIO_CR_MODE_OUTPUT_2MHZ        0x2
+#define GPIO_CR_MODE_OUTPUT_50MHZ       0x3
+
+/**
+ * @brief GPIO Pin modes.
+ *
+ * These only allow for 50MHZ max output speeds; if you want slower,
+ * use direct register access.
+ */
+typedef enum gpio_pin_mode {
+    GPIO_OUTPUT_PP = (GPIO_CR_CNF_OUTPUT_PP |
+                      GPIO_CR_MODE_OUTPUT_50MHZ), /**< Output push-pull. */
+    GPIO_OUTPUT_OD = (GPIO_CR_CNF_OUTPUT_OD |
+                      GPIO_CR_MODE_OUTPUT_50MHZ), /**< Output open-drain. */
+    GPIO_AF_OUTPUT_PP = (GPIO_CR_CNF_AF_OUTPUT_PP |
+                         GPIO_CR_MODE_OUTPUT_50MHZ), /**< Alternate function
+                                                        output push-pull. */
+    GPIO_AF_OUTPUT_OD = (GPIO_CR_CNF_AF_OUTPUT_OD |
+                         GPIO_CR_MODE_OUTPUT_50MHZ), /**< Alternate function
+                                                        output open drain. */
+    GPIO_INPUT_ANALOG = (GPIO_CR_CNF_INPUT_ANALOG |
+                         GPIO_CR_MODE_INPUT), /**< Analog input. */
+    GPIO_INPUT_FLOATING = (GPIO_CR_CNF_INPUT_FLOATING |
+                           GPIO_CR_MODE_INPUT), /**< Input floating. */
+    GPIO_INPUT_PD = (GPIO_CR_CNF_INPUT_PU_PD |
+                     GPIO_CR_MODE_INPUT), /**< Input pull-down. */
+    GPIO_INPUT_PU /**< Input pull-up. */
+    /* GPIO_INPUT_PU treated as a special case, for ODR twiddling */
+} gpio_pin_mode;
+
+/**
+ * @brief Get a GPIO port's corresponding afio_exti_port.
+ * @param dev GPIO device whose afio_exti_port to return.
+ */
+static inline afio_exti_port gpio_exti_port(gpio_dev *dev) {
+    return dev->exti_port;
+}
+
+/*
+ * AFIO register map
+ */
+
+/** AFIO register map */
+typedef struct afio_reg_map {
+    __io uint32 EVCR;        /**< Event control register.  */
+    __io uint32 MAPR;        /**< AF remap and debug I/O configuration
+                                register. */
+    __io uint32 EXTICR1;     /**< External interrupt configuration
+                                register 1. */
+    __io uint32 EXTICR2;     /**< External interrupt configuration
+                                register 2. */
+    __io uint32 EXTICR3;     /**< External interrupt configuration
+                                register 3. */
+    __io uint32 EXTICR4;     /**< External interrupt configuration
+                                register 4. */
+    __io uint32 MAPR2;       /**< AF remap and debug I/O configuration
+                                register 2. */
+} afio_reg_map;
+
+/** AFIO register map base pointer. */
+#define AFIO_BASE                       ((struct afio_reg_map *)0x40010000)
+
+/*
+ * AFIO register bit definitions
+ */
+
+/* Event control register */
+
+#define AFIO_EVCR_EVOE                  (0x1 << 7)
+#define AFIO_EVCR_PORT_PA               (0x0 << 4)
+#define AFIO_EVCR_PORT_PB               (0x1 << 4)
+#define AFIO_EVCR_PORT_PC               (0x2 << 4)
+#define AFIO_EVCR_PORT_PD               (0x3 << 4)
+#define AFIO_EVCR_PORT_PE               (0x4 << 4)
+#define AFIO_EVCR_PIN_0                 0x0
+#define AFIO_EVCR_PIN_1                 0x1
+#define AFIO_EVCR_PIN_2                 0x2
+#define AFIO_EVCR_PIN_3                 0x3
+#define AFIO_EVCR_PIN_4                 0x4
+#define AFIO_EVCR_PIN_5                 0x5
+#define AFIO_EVCR_PIN_6                 0x6
+#define AFIO_EVCR_PIN_7                 0x7
+#define AFIO_EVCR_PIN_8                 0x8
+#define AFIO_EVCR_PIN_9                 0x9
+#define AFIO_EVCR_PIN_10                0xA
+#define AFIO_EVCR_PIN_11                0xB
+#define AFIO_EVCR_PIN_12                0xC
+#define AFIO_EVCR_PIN_13                0xD
+#define AFIO_EVCR_PIN_14                0xE
+#define AFIO_EVCR_PIN_15                0xF
+
+/* AF remap and debug I/O configuration register */
+
+#define AFIO_MAPR_SWJ_CFG                      (0x7 << 24)
+#define AFIO_MAPR_SWJ_CFG_FULL_SWJ             (0x0 << 24)
+#define AFIO_MAPR_SWJ_CFG_FULL_SWJ_NO_NJRST    (0x1 << 24)
+#define AFIO_MAPR_SWJ_CFG_NO_JTAG_SW           (0x2 << 24)
+#define AFIO_MAPR_SWJ_CFG_NO_JTAG_NO_SW        (0x4 << 24)
+#define AFIO_MAPR_ADC2_ETRGREG_REMAP           BIT(20)
+#define AFIO_MAPR_ADC2_ETRGINJ_REMAP           BIT(19)
+#define AFIO_MAPR_ADC1_ETRGREG_REMAP           BIT(18)
+#define AFIO_MAPR_ADC1_ETRGINJ_REMAP           BIT(17)
+#define AFIO_MAPR_TIM5CH4_IREMAP               BIT(16)
+#define AFIO_MAPR_PD01_REMAP                   BIT(15)
+#define AFIO_MAPR_CAN_REMAP                    (0x3 << 13)
+#define AFIO_MAPR_CAN_REMAP_NONE               (0x0 << 13)
+#define AFIO_MAPR_CAN_REMAP_PB8_PB9            (0x2 << 13)
+#define AFIO_MAPR_CAN_REMAP_PD0_PD1            (0x3 << 13)
+#define AFIO_MAPR_TIM4_REMAP                   BIT(12)
+#define AFIO_MAPR_TIM3_REMAP                   (0x3 << 10)
+#define AFIO_MAPR_TIM3_REMAP_NONE              (0x0 << 10)
+#define AFIO_MAPR_TIM3_REMAP_PARTIAL           (0x2 << 10)
+#define AFIO_MAPR_TIM3_REMAP_FULL              (0x3 << 10)
+#define AFIO_MAPR_TIM2_REMAP                   (0x3 << 8)
+#define AFIO_MAPR_TIM2_REMAP_NONE              (0x0 << 8)
+#define AFIO_MAPR_TIM2_REMAP_PA15_PB3_PA2_PA3  (0x1 << 8)
+#define AFIO_MAPR_TIM2_REMAP_PA0_PA1_PB10_PB11 (0x2 << 8)
+#define AFIO_MAPR_TIM2_REMAP_FULL              (0x3 << 8)
+#define AFIO_MAPR_TIM1_REMAP                   (0x3 << 6)
+#define AFIO_MAPR_TIM1_REMAP_NONE              (0x0 << 6)
+#define AFIO_MAPR_TIM1_REMAP_PARTIAL           (0x1 << 6)
+#define AFIO_MAPR_TIM1_REMAP_FULL              (0x3 << 6)
+#define AFIO_MAPR_USART3_REMAP                 (0x3 << 4)
+#define AFIO_MAPR_USART3_REMAP_NONE            (0x0 << 4)
+#define AFIO_MAPR_USART3_REMAP_PARTIAL         (0x1 << 4)
+#define AFIO_MAPR_USART3_REMAP_FULL            (0x3 << 4)
+#define AFIO_MAPR_USART2_REMAP                 BIT(3)
+#define AFIO_MAPR_USART1_REMAP                 BIT(2)
+#define AFIO_MAPR_I2C1_REMAP                   BIT(1)
+#define AFIO_MAPR_SPI1_REMAP                   BIT(0)
+
+/* External interrupt configuration register 1 */
+
+#define AFIO_EXTICR1_EXTI3              (0xF << 12)
+#define AFIO_EXTICR1_EXTI3_PA           (0x0 << 12)
+#define AFIO_EXTICR1_EXTI3_PB           (0x1 << 12)
+#define AFIO_EXTICR1_EXTI3_PC           (0x2 << 12)
+#define AFIO_EXTICR1_EXTI3_PD           (0x3 << 12)
+#define AFIO_EXTICR1_EXTI3_PE           (0x4 << 12)
+#define AFIO_EXTICR1_EXTI3_PF           (0x5 << 12)
+#define AFIO_EXTICR1_EXTI3_PG           (0x6 << 12)
+#define AFIO_EXTICR1_EXTI2              (0xF << 8)
+#define AFIO_EXTICR1_EXTI2_PA           (0x0 << 8)
+#define AFIO_EXTICR1_EXTI2_PB           (0x1 << 8)
+#define AFIO_EXTICR1_EXTI2_PC           (0x2 << 8)
+#define AFIO_EXTICR1_EXTI2_PD           (0x3 << 8)
+#define AFIO_EXTICR1_EXTI2_PE           (0x4 << 8)
+#define AFIO_EXTICR1_EXTI2_PF           (0x5 << 8)
+#define AFIO_EXTICR1_EXTI2_PG           (0x6 << 8)
+#define AFIO_EXTICR1_EXTI1              (0xF << 4)
+#define AFIO_EXTICR1_EXTI1_PA           (0x0 << 4)
+#define AFIO_EXTICR1_EXTI1_PB           (0x1 << 4)
+#define AFIO_EXTICR1_EXTI1_PC           (0x2 << 4)
+#define AFIO_EXTICR1_EXTI1_PD           (0x3 << 4)
+#define AFIO_EXTICR1_EXTI1_PE           (0x4 << 4)
+#define AFIO_EXTICR1_EXTI1_PF           (0x5 << 4)
+#define AFIO_EXTICR1_EXTI1_PG           (0x6 << 4)
+#define AFIO_EXTICR1_EXTI0              0xF
+#define AFIO_EXTICR1_EXTI0_PA           0x0
+#define AFIO_EXTICR1_EXTI0_PB           0x1
+#define AFIO_EXTICR1_EXTI0_PC           0x2
+#define AFIO_EXTICR1_EXTI0_PD           0x3
+#define AFIO_EXTICR1_EXTI0_PE           0x4
+#define AFIO_EXTICR1_EXTI0_PF           0x5
+#define AFIO_EXTICR1_EXTI0_PG           0x6
+
+/* External interrupt configuration register 2 */
+
+#define AFIO_EXTICR2_EXTI7              (0xF << 12)
+#define AFIO_EXTICR2_EXTI7_PA           (0x0 << 12)
+#define AFIO_EXTICR2_EXTI7_PB           (0x1 << 12)
+#define AFIO_EXTICR2_EXTI7_PC           (0x2 << 12)
+#define AFIO_EXTICR2_EXTI7_PD           (0x3 << 12)
+#define AFIO_EXTICR2_EXTI7_PE           (0x4 << 12)
+#define AFIO_EXTICR2_EXTI7_PF           (0x5 << 12)
+#define AFIO_EXTICR2_EXTI7_PG           (0x6 << 12)
+#define AFIO_EXTICR2_EXTI6              (0xF << 8)
+#define AFIO_EXTICR2_EXTI6_PA           (0x0 << 8)
+#define AFIO_EXTICR2_EXTI6_PB           (0x1 << 8)
+#define AFIO_EXTICR2_EXTI6_PC           (0x2 << 8)
+#define AFIO_EXTICR2_EXTI6_PD           (0x3 << 8)
+#define AFIO_EXTICR2_EXTI6_PE           (0x4 << 8)
+#define AFIO_EXTICR2_EXTI6_PF           (0x5 << 8)
+#define AFIO_EXTICR2_EXTI6_PG           (0x6 << 8)
+#define AFIO_EXTICR2_EXTI5              (0xF << 4)
+#define AFIO_EXTICR2_EXTI5_PA           (0x0 << 4)
+#define AFIO_EXTICR2_EXTI5_PB           (0x1 << 4)
+#define AFIO_EXTICR2_EXTI5_PC           (0x2 << 4)
+#define AFIO_EXTICR2_EXTI5_PD           (0x3 << 4)
+#define AFIO_EXTICR2_EXTI5_PE           (0x4 << 4)
+#define AFIO_EXTICR2_EXTI5_PF           (0x5 << 4)
+#define AFIO_EXTICR2_EXTI5_PG           (0x6 << 4)
+#define AFIO_EXTICR2_EXTI4              0xF
+#define AFIO_EXTICR2_EXTI4_PA           0x0
+#define AFIO_EXTICR2_EXTI4_PB           0x1
+#define AFIO_EXTICR2_EXTI4_PC           0x2
+#define AFIO_EXTICR2_EXTI4_PD           0x3
+#define AFIO_EXTICR2_EXTI4_PE           0x4
+#define AFIO_EXTICR2_EXTI4_PF           0x5
+#define AFIO_EXTICR2_EXTI4_PG           0x6
+
+/* AF remap and debug I/O configuration register 2 */
+
+#define AFIO_MAPR2_FSMC_NADV            BIT(10)
+#define AFIO_MAPR2_TIM14_REMAP          BIT(9)
+#define AFIO_MAPR2_TIM13_REMAP          BIT(8)
+#define AFIO_MAPR2_TIM11_REMAP          BIT(7)
+#define AFIO_MAPR2_TIM10_REMAP          BIT(6)
+#define AFIO_MAPR2_TIM9_REMAP           BIT(5)
+
+/*
+ * AFIO convenience routines
+ */
+
+void afio_init(void);
+
+/**
+ * External interrupt line numbers.
+ */
+typedef enum afio_exti_num {
+    AFIO_EXTI_0,                /**< External interrupt line 0. */
+    AFIO_EXTI_1,                /**< External interrupt line 1. */
+    AFIO_EXTI_2,                /**< External interrupt line 2. */
+    AFIO_EXTI_3,                /**< External interrupt line 3. */
+    AFIO_EXTI_4,                /**< External interrupt line 4. */
+    AFIO_EXTI_5,                /**< External interrupt line 5. */
+    AFIO_EXTI_6,                /**< External interrupt line 6. */
+    AFIO_EXTI_7,                /**< External interrupt line 7. */
+    AFIO_EXTI_8,                /**< External interrupt line 8. */
+    AFIO_EXTI_9,                /**< External interrupt line 9. */
+    AFIO_EXTI_10,               /**< External interrupt line 10. */
+    AFIO_EXTI_11,               /**< External interrupt line 11. */
+    AFIO_EXTI_12,               /**< External interrupt line 12. */
+    AFIO_EXTI_13,               /**< External interrupt line 13. */
+    AFIO_EXTI_14,               /**< External interrupt line 14. */
+    AFIO_EXTI_15,               /**< External interrupt line 15. */
+} afio_exti_num;
+
+void afio_exti_select(afio_exti_num exti, afio_exti_port gpio_port);
+
+/* HACK: Use upper bit to denote MAPR2, Bit 31 is reserved and
+ * not used in either MAPR or MAPR2 */
+#define AFIO_REMAP_USE_MAPR2            (1 << 31)
+
+/**
+ * @brief Available peripheral remaps.
+ * @see afio_remap()
+ */
+typedef enum afio_remap_peripheral {
+    AFIO_REMAP_ADC2_ETRGREG  = AFIO_MAPR_ADC2_ETRGREG_REMAP, /**<
+        ADC 2 external trigger regular conversion remapping */
+    AFIO_REMAP_ADC2_ETRGINJ  = AFIO_MAPR_ADC2_ETRGINJ_REMAP, /**<
+        ADC 2 external trigger injected conversion remapping */
+    AFIO_REMAP_ADC1_ETRGREG  = AFIO_MAPR_ADC1_ETRGREG_REMAP, /**<
+        ADC 1 external trigger regular conversion remapping */
+    AFIO_REMAP_ADC1_ETRGINJ  = AFIO_MAPR_ADC1_ETRGINJ_REMAP, /**<
+        ADC 1 external trigger injected conversion remapping */
+    AFIO_REMAP_TIM5CH4_I     = AFIO_MAPR_TIM5CH4_IREMAP, /**<
+        Timer 5 channel 4 internal remapping */
+    AFIO_REMAP_PD01          = AFIO_MAPR_PD01_REMAP, /**<
+        Port D0/Port D1 mapping on OSC_IN/OSC_OUT */
+    AFIO_REMAP_CAN_1         = AFIO_MAPR_CAN_REMAP_PB8_PB9, /**<
+        CAN alternate function remapping 1 (RX on PB8, TX on PB9) */
+    AFIO_REMAP_CAN_2         = AFIO_MAPR_CAN_REMAP_PD0_PD1, /**<
+        CAN alternate function remapping 2 (RX on PD0, TX on PD1) */
+    AFIO_REMAP_TIM4          = AFIO_MAPR_TIM4_REMAP, /**<
+        Timer 4 remapping */
+    AFIO_REMAP_TIM3_PARTIAL  = AFIO_MAPR_TIM3_REMAP_PARTIAL, /**<
+        Timer 3 partial remapping */
+    AFIO_REMAP_TIM3_FULL      = AFIO_MAPR_TIM3_REMAP_FULL, /**<
+        Timer 3 full remapping */
+    AFIO_REMAP_TIM2_PARTIAL_1 = AFIO_MAPR_TIM2_REMAP_PA15_PB3_PA2_PA3, /**<
+        Timer 2 partial remapping 1 (CH1 and ETR on PA15, CH2 on PB3, CH3
+        on PA2, CH4 on PA3) */
+    AFIO_REMAP_TIM2_PARTIAL_2 = AFIO_MAPR_TIM2_REMAP_PA0_PA1_PB10_PB11, /**<
+        Timer 2 partial remapping 2 (CH1 and ETR on PA0, CH2 on PA1, CH3
+        on PB10, CH4 on PB11) */
+    AFIO_REMAP_TIM2_FULL      = AFIO_MAPR_TIM2_REMAP_FULL, /**<
+        Timer 2 full remapping */
+    AFIO_REMAP_USART2        = AFIO_MAPR_USART2_REMAP, /**<
+        USART 2 remapping */
+    AFIO_REMAP_USART1        = AFIO_MAPR_USART1_REMAP, /**<
+        USART 1 remapping */
+    AFIO_REMAP_I2C1          = AFIO_MAPR_I2C1_REMAP, /**<
+        I2C 1 remapping */
+    AFIO_REMAP_SPI1          = AFIO_MAPR_SPI1_REMAP, /**<
+        SPI 1 remapping */
+    AFIO_REMAP_FSMC_NADV     = (AFIO_MAPR2_FSMC_NADV |
+                                AFIO_REMAP_USE_MAPR2), /**<
+        NADV signal not connected */
+    AFIO_REMAP_TIM14         = (AFIO_MAPR2_TIM14_REMAP |
+                                AFIO_REMAP_USE_MAPR2), /**<
+        Timer 14 remapping */
+    AFIO_REMAP_TIM13         = (AFIO_MAPR2_TIM13_REMAP |
+                                AFIO_REMAP_USE_MAPR2), /**<
+        Timer 13 remapping */
+    AFIO_REMAP_TIM11         = (AFIO_MAPR2_TIM11_REMAP |
+                                AFIO_REMAP_USE_MAPR2), /**<
+        Timer 11 remapping */
+    AFIO_REMAP_TIM10         = (AFIO_MAPR2_TIM10_REMAP |
+                                AFIO_REMAP_USE_MAPR2), /**<
+        Timer 10 remapping */
+    AFIO_REMAP_TIM9          = (AFIO_MAPR2_TIM9_REMAP |
+                                AFIO_REMAP_USE_MAPR2) /**<
+        Timer 9 */
+} afio_remap_peripheral;
+
+void afio_remap(afio_remap_peripheral p);
+
+/**
+ * @brief Debug port configuration
+ *
+ * Used to configure the behavior of JTAG and Serial Wire (SW) debug
+ * ports and their associated GPIO pins.
+ *
+ * @see afio_cfg_debug_ports()
+ */
+typedef enum afio_debug_cfg {
+    AFIO_DEBUG_FULL_SWJ = AFIO_MAPR_SWJ_CFG_FULL_SWJ, /**<
+                                   Full Serial Wire and JTAG debug */
+    AFIO_DEBUG_FULL_SWJ_NO_NJRST = AFIO_MAPR_SWJ_CFG_FULL_SWJ_NO_NJRST, /**<
+                                   Full Serial Wire and JTAG, but no NJTRST. */
+    AFIO_DEBUG_SW_ONLY = AFIO_MAPR_SWJ_CFG_NO_JTAG_SW, /**<
+                                   Serial Wire debug only (JTAG-DP disabled,
+                                   SW-DP enabled) */
+    AFIO_DEBUG_NONE = AFIO_MAPR_SWJ_CFG_NO_JTAG_NO_SW /**<
+                                   No debug; all JTAG and SW pins are free
+                                   for use as GPIOs. */
+} afio_debug_cfg;
+
+/**
+ * @brief Enable or disable the JTAG and SW debug ports.
+ * @param config Desired debug port configuration
+ * @see afio_debug_cfg
+ */
+static inline void afio_cfg_debug_ports(afio_debug_cfg config) {
+    __io uint32 *mapr = &AFIO_BASE->MAPR;
+    *mapr = (*mapr & ~AFIO_MAPR_SWJ_CFG) | config;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/libmaple/stm32f1/rules.mk b/libmaple/stm32f1/rules.mk
index 2bdc423..03d2f95 100644
--- a/libmaple/stm32f1/rules.mk
+++ b/libmaple/stm32f1/rules.mk
@@ -13,6 +13,7 @@ sSRCS_$(d) := isrs_performance.S            \
 
 cSRCS_$(d) := rcc.c
 cSRCS_$(d) += flash.c
+cSRCS_$(d) += gpio.c
 
 sFILES_$(d) := $(sSRCS_$(d):%=$(d)/%)
 cFILES_$(d) := $(cSRCS_$(d):%=$(d)/%)