atsam: Add support for hard pwm via PWM controller

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 96 insertions, 0 deletions

diff --git a/src/atsam/hard_pwm.c b/src/atsam/hard_pwm.c
new file mode 100644
index 00000000..8bfd6305
--- /dev/null
+++ b/src/atsam/hard_pwm.c
@@ -0,0 +1,96 @@
+// 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;
+}