drivers/gpio.c

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+/** @file gpio.c
+ * Module handling General Purpose Input/Output (GPIO) pins
+ *
+ * The module provides functions to configure the gpio pins and read from/
+ * write to them
+ */
+
+//--includes--------------------------------------------------------------------
+
+#include "gpio.h"
+#include "gpio_regs.h"
+
+#include "rcc.h"
+
+
+//--local definitions-----------------------------------------------------------
+
+static volatile struct GPIO* regs = (struct GPIO*)GPIO_BASE_ADDRESS;
+
+
+//--local variables-------------------------------------------------------------
+
+//--public functions------------------------------------------------------------
+
+/**
+ * Use the provided mask to generate its equivalent with 3 bits of padding
+ * between each initial bit. This new mask matches the registers layout and
+ * allow for direct application of the mode and config. Outputs are disabled
+ * prior to confiiguration to avoid any glitches. The relevant clocks are
+ * automatically enabled for the ports used
+ */
+void gpio_configure(enum GpioPort port, enum GpioPin pin_mask,
+		enum GpioMode mode, enum GpioConfig config)
+{
+	//ensure gpio port is enabled
+	rcc_enable(RCC_AHB_NONE, RCC_APB1_NONE, RCC_APB2_IOPA << port);
+
+	//reset outputs before configuring anything
+	regs->PORTS[port].BRR.word |= pin_mask;
+
+	//clear config for selected port, then apply new config, 8 first pins
+	uint32_t mask = 0;
+	for (uint8_t i=0; i<8; ++i)
+	{
+		if (pin_mask & (0x1 << i))
+		{
+			mask |= 0x1 << (i * 4);
+		}
+	}
+	regs->PORTS[port].CRL.word &= ~(0xF * mask);
+	regs->PORTS[port].CRL.word |= (config << 2) | (mode << 0) * mask;
+
+	//clear config for selected port, then apply new config, 8 last pins
+	mask = 0;
+	pin_mask = pin_mask >> 8;
+	for (uint8_t i=0; i<8; ++i)
+	{
+		if (pin_mask & (0x1 << i))
+		{
+			mask |= 0x1 << (i * 4);
+		}
+	}
+	regs->PORTS[port].CRH.word &= ~(0xF * mask);
+	regs->PORTS[port].CRH.word |= (config << 2) | (mode << 0) * mask;
+}
+
+void gpio_reset(enum GpioPort port, enum GpioPin pin_mask)
+{
+	gpio_configure(port, pin_mask, GPIO_MODE_INPUT, GPIO_CONFIG_IN_FLOATING);
+}
+
+void gpio_write(enum GpioPort port, enum GpioPin pin_mask, bool value)
+{
+	if (value) {
+		regs->PORTS[port].BSRR.word |= pin_mask;
+	} else {
+		regs->PORTS[port].BRR.word |= pin_mask;
+	}
+}
+
+bool gpio_read(enum GpioPort port, enum GpioPin pin_mask)
+{
+	return (regs->PORTS[port].IDR.word & pin_mask) == pin_mask;
+}
+
+
+//--local functions-------------------------------------------------------------

drivers/gpio.h

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+/** @file gpio.h
+ * Module handling General Purpose Input/Output (GPIO) pins
+ *
+ * The module provides functions to configure the gpio pins and read from/
+ * write to them
+ */
+
+#ifndef _GPIO_H_
+#define _GPIO_H_
+
+//--includes--------------------------------------------------------------------
+
+#include "stdint.h"
+#include "stdbool.h"
+
+
+//--type definitions------------------------------------------------------------
+
+/**
+ * Available GPIO ports. Note that not all ports may be available for a
+ * particular chip
+ */
+enum GpioPort {
+	GPIO_PORT_A = 0,
+	GPIO_PORT_B,
+	GPIO_PORT_C,
+	GPIO_PORT_D,
+	GPIO_PORT_E,
+	GPIO_PORT_F,
+	GPIO_PORT_G,
+};
+
+/**
+ * Availables pin for a particular port. Note that all ports available may not
+ * have all the pins listed here and that some pins may be used by defaut (jtag,
+ * ...)
+ */
+enum GpioPin {
+	GPIO_PIN_0  = (0x1 <<  0),
+	GPIO_PIN_1  = (0x1 <<  1),
+	GPIO_PIN_2  = (0x1 <<  2),
+	GPIO_PIN_3  = (0x1 <<  3),
+	GPIO_PIN_4  = (0x1 <<  4),
+	GPIO_PIN_5  = (0x1 <<  5),
+	GPIO_PIN_6  = (0x1 <<  6),
+	GPIO_PIN_7  = (0x1 <<  7),
+	GPIO_PIN_8  = (0x1 <<  8),
+	GPIO_PIN_9  = (0x1 <<  9),
+	GPIO_PIN_10 = (0x1 << 10),
+	GPIO_PIN_11 = (0x1 << 11),
+	GPIO_PIN_12 = (0x1 << 12),
+	GPIO_PIN_13 = (0x1 << 13),
+	GPIO_PIN_14 = (0x1 << 14),
+	GPIO_PIN_15 = (0x1 << 15),
+};
+
+/**
+ * Available modes for a pin. To have a pin in both modes simultaneously, see
+ * push-pull configuration in input mode
+ */
+enum GpioMode {
+	GPIO_MODE_INPUT = 0,
+	GPIO_MODE_OUTPUT,      //10MHz max
+	GPIO_MODE_OUTPUT_SLOW, //2MHz max
+	GPIO_MODE_OUTPUT_FAST, //50MHz max
+};
+
+/**
+ * Available configurations for a pin. Some configurations onlly apply in input
+ * mode (denoted "IN") while others only apply in output mode (denoted "OUT")
+ */
+enum GpioConfig {
+	GPIO_CONFIG_IN_ANALOG          = 0,
+	GPIO_CONFIG_IN_FLOATING,
+	GPIO_CONFIG_IN_PUSH_PULL,      //use gpio_write() to configure pull_up/down
+	GPIO_CONFIG_OUT_PUSH_PULL      = 0,
+	GPIO_CONFIG_OUT_OPEN_DRAIN,
+	GPIO_CONFIG_OUT_ALT_PUSH_PULL,
+	GPIO_CONFIG_OUT_ALT_OPEN_DRAIN,
+};
+
+
+//--functions-------------------------------------------------------------------
+
+/**
+ * Configures gpio pins on a single port. The GpioPin enum can be used as mask
+ * to configure multiple pins at the same time. Before configuring a pin, make
+ * sure it isn't used somewhere else (peripherals, jtag, ...). After
+ * configuration, the selected output pins are set to output 0V
+ */
+void gpio_configure(enum GpioPort port, enum GpioPin pin_mask,
+		enum GpioMode mode, enum GpioConfig config);
+
+/**
+ * Resets gpio pins on a single port. The GpioPin enum can be used as mask
+ * to reset multiple pins at the same time. This is a simple wrapper over
+ * gpio_configure(), setting the selected ports as floating input
+ */
+void gpio_reset(enum GpioPort port, enum GpioPin pin_mask);
+
+/**
+ * Write a value to output gpios on a single port. The GpioPin enum can be used
+ * as mask to reset multiple pins at the same time. In push-pull input mode,
+ * configure the pull up/down. Has no effect otherwise
+ */
+void gpio_write(enum GpioPort port, enum GpioPin pin_mask, bool value);
+
+/**
+ * Reads the value of gpios on a single port. The GpioPin enum can be used
+ * as mask to read multiple pins at the same time. For output pins, reads the
+ * pin state. Returns true if all selected ports are high
+ */
+bool gpio_read(enum GpioPort port, enum GpioPin pin_mask);
+
+
+#endif //_RCC_H_