From 3e4328140c96626312cae680d4d781acf61da7f9 Mon Sep 17 00:00:00 2001
From: Dan Halbert <halbert@halwitz.org>
Date: Fri, 12 Feb 2021 15:34:36 -0500
Subject: [PATCH] fix off-by-one PWM top issue

---
 ports/raspberrypi/common-hal/pwmio/PWMOut.c     | 17 +++++++++--------
 ports/raspberrypi/common-hal/pwmio/PWMOut.h     |  4 ++--
 shared-bindings/adafruit_bus_device/SPIDevice.c |  1 -
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/ports/raspberrypi/common-hal/pwmio/PWMOut.c b/ports/raspberrypi/common-hal/pwmio/PWMOut.c
index e861bab5a9..b4e7caa25a 100644
--- a/ports/raspberrypi/common-hal/pwmio/PWMOut.c
+++ b/ports/raspberrypi/common-hal/pwmio/PWMOut.c
@@ -164,7 +164,8 @@ void common_hal_pwmio_pwmout_deinit(pwmio_pwmout_obj_t* self) {
 
 extern void common_hal_pwmio_pwmout_set_duty_cycle(pwmio_pwmout_obj_t* self, uint16_t duty) {
     self->duty_cycle = duty;
-    uint16_t actual_duty = duty * self->top / ((1 << 16) - 1);
+    // Do arithmetic in 32 bits to prevent overflow.
+    uint16_t actual_duty = (uint32_t) duty * self->top / ((1 << 16) - 1);
     pwm_set_chan_level(self->slice, self->channel, actual_duty);
 }
 
@@ -172,11 +173,11 @@ uint16_t common_hal_pwmio_pwmout_get_duty_cycle(pwmio_pwmout_obj_t* self) {
     return self->duty_cycle;
 }
 
-void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint32_t top) {
+void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint16_t top) {
     self->actual_frequency = common_hal_mcu_processor_get_frequency() / top;
     self->top = top;
     pwm_set_clkdiv_int_frac(self->slice, 1, 0);
-    pwm_set_wrap(self->slice, self->top - 1);
+    pwm_set_wrap(self->slice, self->top);
 }
 
 void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self, uint32_t frequency) {
@@ -187,7 +188,7 @@ void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self, uint32_t fr
     target_slice_frequencies[self->slice] = frequency;
 
     // For low frequencies use the divider to give us full resolution duty_cycle.
-    if (frequency < (common_hal_mcu_processor_get_frequency() / (1 << 16))) {
+    if (frequency <= (common_hal_mcu_processor_get_frequency() / (1 << 16))) {
         // Compute the divisor. It's an 8 bit integer and 4 bit fraction. Therefore,
         // we compute everything * 16 for the fractional part.
         // This is 1 << 12 because 4 bits are the * 16.
@@ -202,15 +203,15 @@ void common_hal_pwmio_pwmout_set_frequency(pwmio_pwmout_obj_t* self, uint32_t fr
             div16 = (1 << 12) - 1;
         }
         self->actual_frequency = frequency16 / div16;
-        self->top = 1 << 16;
+        self->top = (1 << 16) - 1;
         pwm_set_clkdiv_int_frac(self->slice, div16 / 16, div16 % 16);
-        pwm_set_wrap(self->slice, self->top - 1);
+        pwm_set_wrap(self->slice, self->top);
     } else {
         uint32_t top = common_hal_mcu_processor_get_frequency() / frequency;
         self->actual_frequency = common_hal_mcu_processor_get_frequency() / top;
-        self->top = top;
+        self->top = MIN(UINT16_MAX, top - 1);
         pwm_set_clkdiv_int_frac(self->slice, 1, 0);
-        pwm_set_wrap(self->slice, self->top - 1);
+        pwm_set_wrap(self->slice, self->top);
     }
     common_hal_pwmio_pwmout_set_duty_cycle(self, self->duty_cycle);
 }
diff --git a/ports/raspberrypi/common-hal/pwmio/PWMOut.h b/ports/raspberrypi/common-hal/pwmio/PWMOut.h
index cbb0b707a3..0070e188b5 100644
--- a/ports/raspberrypi/common-hal/pwmio/PWMOut.h
+++ b/ports/raspberrypi/common-hal/pwmio/PWMOut.h
@@ -39,11 +39,11 @@ typedef struct {
     bool variable_frequency;
     uint16_t duty_cycle;
     uint32_t actual_frequency;
-    uint32_t top;
+    uint16_t top;
 } pwmio_pwmout_obj_t;
 
 void pwmout_reset(void);
 // Private API for AudioPWMOut.
-void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint32_t top);
+void pwmio_pwmout_set_top(pwmio_pwmout_obj_t* self, uint16_t top);
 
 #endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_PWMIO_PWMOUT_H
diff --git a/shared-bindings/adafruit_bus_device/SPIDevice.c b/shared-bindings/adafruit_bus_device/SPIDevice.c
index ec1f53c858..74fa28e4d5 100644
--- a/shared-bindings/adafruit_bus_device/SPIDevice.c
+++ b/shared-bindings/adafruit_bus_device/SPIDevice.c
@@ -34,7 +34,6 @@
 
 #include "lib/utils/buffer_helper.h"
 #include "lib/utils/context_manager_helpers.h"
-#include "py/objproperty.h"
 #include "py/runtime.h"
 #include "supervisor/shared/translate.h"