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// Hardware PWM support on atsam
//
// Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "command.h" // shutdown
#include "gpio.h" // gpio_pwm_write
#include "internal.h" // GPIO
#include "sched.h" // sched_shutdown
struct gpio_pwm_info {
uint8_t gpio, channel, ptype;
};
static const struct gpio_pwm_info pwm_regs[] = {
#if CONFIG_MACH_SAM3X
{ GPIO('A', 21), 0, 'B' },
{ GPIO('B', 16), 0, 'B' },
{ GPIO('A', 12), 1, 'B' },
{ GPIO('B', 17), 1, 'B' },
{ GPIO('A', 20), 2, 'B' },
{ GPIO('B', 18), 2, 'B' },
{ GPIO('A', 0), 3, 'B' },
{ GPIO('B', 19), 3, 'B' },
#if CONFIG_MACH_SAM3X8E
{ GPIO('C', 2), 0, 'B' },
{ GPIO('C', 4), 1, 'B' },
{ GPIO('C', 6), 2, 'B' },
{ GPIO('C', 8), 3, 'B' },
{ GPIO('C', 21), 4, 'B' },
{ GPIO('C', 22), 5, 'B' },
{ GPIO('C', 23), 6, 'B' },
{ GPIO('C', 24), 7, 'B' },
#endif
#elif CONFIG_MACH_SAM4
{ GPIO('A', 19), 0, 'B' },
{ GPIO('B', 5), 0, 'B' },
{ GPIO('C', 0), 0, 'B' },
{ GPIO('C', 13), 0, 'B' },
{ GPIO('A', 20), 1, 'B' },
{ GPIO('B', 12), 1, 'A' },
{ GPIO('C', 1), 1, 'B' },
{ GPIO('C', 15), 1, 'B' },
{ GPIO('A', 16), 2, 'C' },
{ GPIO('A', 30), 2, 'A' },
{ GPIO('B', 13), 2, 'A' },
{ GPIO('C', 2), 2, 'B' },
{ GPIO('A', 15), 3, 'C' },
{ GPIO('C', 3), 3, 'B' },
{ GPIO('C', 22), 3, 'B' },
#endif
};
#define MAX_PWM 255
DECL_CONSTANT(PWM_MAX, MAX_PWM);
struct gpio_pwm
gpio_pwm_setup(uint8_t pin, uint32_t cycle_time, uint8_t val)
{
// Find pin in pwm_regs table
const struct gpio_pwm_info *p = pwm_regs;
for (; ; p++) {
if (p >= &pwm_regs[ARRAY_SIZE(pwm_regs)])
shutdown("Not a valid PWM pin");
if (p->gpio == pin)
break;
}
// Map cycle_time to pwm clock divisor
uint32_t div;
for (div=0; div<10; div++)
if (cycle_time < (MAX_PWM << div) / 2)
break;
// Enable clock
enable_pclock(ID_PWM);
// Enable PWM output
if (PWM->PWM_SR & (1 << p->channel))
shutdown("PWM channel already in use");
gpio_peripheral(pin, p->ptype, 0);
PWM->PWM_CH_NUM[p->channel].PWM_CMR = div;
PWM->PWM_CH_NUM[p->channel].PWM_CPRD = MAX_PWM;
PWM->PWM_CH_NUM[p->channel].PWM_CDTY = val;
PWM->PWM_ENA = 1 << p->channel;
return (struct gpio_pwm){ (void*)&PWM->PWM_CH_NUM[p->channel].PWM_CDTYUPD };
}
void
gpio_pwm_write(struct gpio_pwm g, uint8_t val)
{
*(volatile uint32_t*)g.reg = val;
}
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