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// GPIO functions on sam3x8e
//
// Copyright (C) 2016,2017 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include <stdint.h> // uint32_t
#include "autoconf.h" // CONFIG_CLOCK_FREQ
#include "board/irq.h" // irq_save
#include "command.h" // shutdown
#include "compiler.h" // ARRAY_SIZE
#include "gpio.h" // gpio_out_setup
#include "internal.h" // gpio_peripheral
#include "sam3x8e.h" // Pio
#include "sched.h" // sched_shutdown
static Pio * const digital_regs[] = {
PIOA, PIOB, PIOC, PIOD
};
/****************************************************************
* Pin multiplexing
****************************************************************/
void
gpio_peripheral(uint32_t gpio, char ptype, int32_t pull_up)
{
uint32_t bank = GPIO2PORT(gpio), bit = GPIO2BIT(gpio);
Pio *regs = digital_regs[bank];
if (ptype == 'A')
regs->PIO_ABSR &= ~bit;
else
regs->PIO_ABSR |= bit;
if (pull_up > 0)
regs->PIO_PUER = bit;
else
regs->PIO_PUDR = bit;
regs->PIO_PDR = bit;
}
/****************************************************************
* General Purpose Input Output (GPIO) pins
****************************************************************/
struct gpio_out
gpio_out_setup(uint8_t pin, uint8_t val)
{
if (GPIO2PORT(pin) >= ARRAY_SIZE(digital_regs))
goto fail;
Pio *regs = digital_regs[GPIO2PORT(pin)];
struct gpio_out g = { .regs=regs, .bit=GPIO2BIT(pin) };
gpio_out_reset(g, val);
return g;
fail:
shutdown("Not an output pin");
}
void
gpio_out_reset(struct gpio_out g, uint8_t val)
{
Pio *regs = g.regs;
irqstatus_t flag = irq_save();
if (val)
regs->PIO_SODR = g.bit;
else
regs->PIO_CODR = g.bit;
regs->PIO_OER = g.bit;
regs->PIO_OWER = g.bit;
regs->PIO_PER = g.bit;
regs->PIO_PUDR = g.bit;
irq_restore(flag);
}
void
gpio_out_toggle_noirq(struct gpio_out g)
{
Pio *regs = g.regs;
regs->PIO_ODSR ^= g.bit;
}
void
gpio_out_toggle(struct gpio_out g)
{
irqstatus_t flag = irq_save();
gpio_out_toggle_noirq(g);
irq_restore(flag);
}
void
gpio_out_write(struct gpio_out g, uint8_t val)
{
Pio *regs = g.regs;
if (val)
regs->PIO_SODR = g.bit;
else
regs->PIO_CODR = g.bit;
}
struct gpio_in
gpio_in_setup(uint8_t pin, int8_t pull_up)
{
if (GPIO2PORT(pin) >= ARRAY_SIZE(digital_regs))
goto fail;
uint32_t port = GPIO2PORT(pin);
PMC->PMC_PCER0 = 1 << (ID_PIOA + port);
struct gpio_in g = { .regs=digital_regs[port], .bit=GPIO2BIT(pin) };
gpio_in_reset(g, pull_up);
return g;
fail:
shutdown("Not an input pin");
}
void
gpio_in_reset(struct gpio_in g, int8_t pull_up)
{
Pio *regs = g.regs;
irqstatus_t flag = irq_save();
if (pull_up)
regs->PIO_PUER = g.bit;
else
regs->PIO_PUDR = g.bit;
regs->PIO_ODR = g.bit;
regs->PIO_PER = g.bit;
irq_restore(flag);
}
uint8_t
gpio_in_read(struct gpio_in g)
{
Pio *regs = g.regs;
return !!(regs->PIO_PDSR & g.bit);
}
/****************************************************************
* Analog to Digital Converter (ADC) pins
****************************************************************/
static const uint8_t adc_pins[] = {
GPIO('A', 2), GPIO('A', 3), GPIO('A', 4), GPIO('A', 6),
GPIO('A', 22), GPIO('A', 23), GPIO('A', 24), GPIO('A', 16),
GPIO('B', 12), GPIO('B', 13), GPIO('B', 17), GPIO('B', 18),
GPIO('B', 19), GPIO('B', 20)
};
#define ADC_FREQ_MAX 20000000
DECL_CONSTANT(ADC_MAX, 4095);
struct gpio_adc
gpio_adc_setup(uint8_t pin)
{
// Find pin in adc_pins table
int chan;
for (chan=0; ; chan++) {
if (chan >= ARRAY_SIZE(adc_pins))
shutdown("Not a valid ADC pin");
if (adc_pins[chan] == pin)
break;
}
if (!(PMC->PMC_PCSR1 & (1 << (ID_ADC-32)))) {
// Setup ADC
PMC->PMC_PCER1 = 1 << (ID_ADC-32);
uint32_t prescal = SystemCoreClock / (2 * ADC_FREQ_MAX) - 1;
ADC->ADC_MR = (ADC_MR_PRESCAL(prescal)
| ADC_MR_STARTUP_SUT768
| ADC_MR_TRANSFER(1));
}
return (struct gpio_adc){ .bit = 1 << chan };
}
// Try to sample a value. Returns zero if sample ready, otherwise
// returns the number of clock ticks the caller should wait before
// retrying this function.
uint32_t
gpio_adc_sample(struct gpio_adc g)
{
uint32_t chsr = ADC->ADC_CHSR & 0xffff;
if (!chsr) {
// Start sample
ADC->ADC_CHER = g.bit;
ADC->ADC_CR = ADC_CR_START;
goto need_delay;
}
if (chsr != g.bit)
// Sampling in progress on another channel
goto need_delay;
if (!(ADC->ADC_ISR & ADC_ISR_DRDY))
// Conversion still in progress
goto need_delay;
// Conversion ready
return 0;
need_delay:
return ADC_FREQ_MAX * 1000ULL / CONFIG_CLOCK_FREQ;
}
// Read a value; use only after gpio_adc_sample() returns zero
uint16_t
gpio_adc_read(struct gpio_adc g)
{
ADC->ADC_CHDR = g.bit;
return ADC->ADC_LCDR;
}
// Cancel a sample that may have been started with gpio_adc_sample()
void
gpio_adc_cancel_sample(struct gpio_adc g)
{
irqstatus_t flag = irq_save();
if ((ADC->ADC_CHSR & 0xffff) == g.bit)
gpio_adc_read(g);
irq_restore(flag);
}
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