Add neopixel support on PWM capable pins

It'll be hard to do PWM from them concurrently

Fixes #5697

.pre-commit-config.yaml

@@ -4,7 +4,7 @@
 
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.3.0
+    rev: v4.0.1
     hooks:
     -   id: check-yaml
     -   id: end-of-file-fixer

ports/broadcom/Makefile

@@ -82,7 +82,7 @@ SRC_SHARED_MODULE_EXPANDED = $(addprefix shared-bindings/, $(SRC_SHARED_MODULE))
 # because a few modules have files both in common-hal/ and shared-modules/.
 # Doing a $(sort ...) removes duplicates as part of sorting.
 SRC_COMMON_HAL_SHARED_MODULE_EXPANDED = $(sort $(SRC_COMMON_HAL_EXPANDED) $(SRC_SHARED_MODULE_EXPANDED))
-SRC_S = peripherals/broadcom/boot.s
+SRC_S = peripherals/broadcom/boot8.s
 
 OBJ = $(PY_O) $(SUPERVISOR_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_COMMON_HAL_SHARED_MODULE_EXPANDED:.c=.o))
@@ -134,7 +134,7 @@ CFLAGS += $(INC) -Wall -Werror -std=gnu11 $(BASE_CFLAGS) $(CFLAGS_MOD) $(COPT) $
 
 SRC_QSTR += $(SRC_C) $(SRC_SUPERVISOR) $(SRC_COMMON_HAL_EXPANDED) $(SRC_SHARED_MODULE_EXPANDED)
 
-LDFLAGS += $(CFLAGS) -T peripherals/broadcom/link.ld -Wl,--gc-sections -Wl,-Map=$@.map # -Wl,--cref
+LDFLAGS += $(CFLAGS) -T peripherals/broadcom/link8.ld -Wl,--gc-sections -Wl,-Map=$@.map # -Wl,--cref
 
 # Use toolchain libm if we're not using our own.
 ifndef INTERNAL_LIBM

ports/broadcom/common-hal/microcontroller/__init__.c

@@ -29,6 +29,7 @@
 #include "shared-bindings/microcontroller/Pin.h"
 #include "shared-bindings/microcontroller/Processor.h"
 #include "common-hal/microcontroller/__init__.h"
+#include "peripherals/broadcom/defines.h"
 #include "peripherals/broadcom/interrupts.h"
 
 #include "mphalport.h"

ports/broadcom/common-hal/neopixel_write/__init__.c

@@ -0,0 +1,158 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "shared-bindings/neopixel_write/__init__.h"
+
+#include "py/runtime.h"
+
+#include "shared-bindings/microcontroller/__init__.h"
+#include "shared-bindings/digitalio/DigitalInOut.h"
+#include "shared-bindings/time/__init__.h"
+
+#include "peripherals/broadcom/cpu.h"
+
+#include "supervisor/port.h"
+
+uint64_t next_start_raw_ticks = 0;
+
+// NeoPixels are 800khz bit streams. Zeroes are 1/3 duty cycle (~416ns) and ones
+// are 2/3 duty cycle (~833ns).
+
+void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout,
+    uint8_t *pixels, uint32_t num_bytes) {
+    // Wait to make sure we don't append onto the last transmission. This should only be a tick or
+    // two.
+    while (port_get_raw_ticks(NULL) < next_start_raw_ticks) {
+    }
+
+    BP_Function_Enum alt_function;
+    uint8_t index;
+    uint8_t channel;
+    bool found = false;
+    for (size_t i = 0; i < NUM_ALT_FUNC; i++) {
+        const pin_function_t *f = &digitalinout->pin->functions[i];
+        if (f->type == PIN_FUNCTION_PWM) {
+            index = f->index;
+            channel = f->function;
+            alt_function = FSEL_VALUES[i];
+            found = true;
+            break;
+        }
+    }
+    if (!found) {
+        mp_raise_ValueError(translate("NeoPixel not supported on pin"));
+        return;
+    }
+
+    // Turn on the PWM clock. The speed is NeoPixel specific.
+    if (CM_PWM->CS_b.BUSY == 0) {
+        uint32_t source_clock;
+        #if BCM_VERSION == 2711
+        source_clock = 54000000;
+        #else
+        source_clock = 19200000;
+        #endif
+        // Three clocks per 800khz bit to get the 1/3 or 2/3 timing.
+        uint32_t target_clock = 3 * 800000;
+        uint32_t int_div = source_clock / target_clock;
+
+        CM_PWM->DIV = CM_PCM_DIV_PASSWD_PASSWD << CM_PCM_DIV_PASSWD_Pos |
+                    (int_div) << CM_PCM_DIV_DIVI_Pos;
+
+        CM_PWM->CS = CM_PCM_CS_PASSWD_PASSWD << CM_PCM_CS_PASSWD_Pos |
+            CM_PCM_CS_SRC_XOSC << CM_PCM_CS_SRC_Pos;
+
+        // Set enable after setting the source to ensure it is stable.
+        CM_PWM->CS = CM_PCM_CS_PASSWD_PASSWD << CM_PCM_CS_PASSWD_Pos |
+            CM_PCM_CS_SRC_XOSC << CM_PCM_CS_SRC_Pos |
+            CM_PCM_CS_ENAB_Msk;
+
+        // Wait for the clock to start up.
+        COMPLETE_MEMORY_READS;
+        while (CM_PWM->CS_b.BUSY == 0) {
+        }
+    }
+
+    PWM0_Type *pwm = PWM0;
+    #if BCM_VERSION == 2711
+    if (index == 1) {
+        pwm = PWM1;
+    }
+    #endif
+
+    pwm->RNG1 = 24;
+    pwm->RNG2 = 24;
+    COMPLETE_MEMORY_READS;
+    pwm->CTL = PWM0_CTL_CLRF1_Msk;
+    COMPLETE_MEMORY_READS;
+
+    // Even though we're only transmitting one channel, we enable both. Without
+    // the second channel enabled, the output is repeated forever.
+    pwm->CTL =
+        PWM0_CTL_USEF2_Msk |
+        PWM0_CTL_MODE2_Msk |
+        PWM0_CTL_USEF1_Msk |
+        PWM0_CTL_MODE1_Msk;
+
+    COMPLETE_MEMORY_READS;
+    pwm->CTL |= PWM0_CTL_PWEN1_Msk | PWM0_CTL_PWEN2_Msk;
+
+    gpio_set_function(digitalinout->pin->number, alt_function);
+
+    for (size_t i = 0; i < num_bytes; i++) {
+        uint32_t expanded = 0;
+        for (size_t j = 0; j < 8; j++) {
+            expanded = expanded >> 3;
+            if ((pixels[i] & (1 << j)) != 0) {
+                expanded |= 0xc0000000;
+            } else {
+                expanded |= 0x80000000;
+            }
+        }
+        while (pwm->STA_b.FULL1 == 1) {
+            RUN_BACKGROUND_TASKS;
+        }
+        if (channel == 1) {
+            // Dummy value for the first channel.
+            pwm->FIF1 = 0x000000;
+        }
+        pwm->FIF1 = expanded;
+        if (channel == 0) {
+            // Dummy value for the second channel.
+            pwm->FIF1 = 0x000000;
+        }
+    }
+    // Wait just a little bit so that transmission can start.
+    common_hal_mcu_delay_us(2);
+    while (pwm->STA_b.STA1 == 1) {
+        RUN_BACKGROUND_TASKS;
+    }
+
+    gpio_set_function(digitalinout->pin->number, GPIO_FUNCTION_OUTPUT);
+
+    // Update the next start.
+    next_start_raw_ticks = port_get_raw_ticks(NULL) + 1;
+}

ports/broadcom/mpconfigport.mk

@@ -8,7 +8,7 @@ CIRCUITPY_BUSIO = 1
 CIRCUITPY_ONEWIREIO = 0
 CIRCUITPY_PWMIO = 0
 CIRCUITPY_COUNTIO = 0
-CIRCUITPY_NEOPIXEL_WRITE = 0
+CIRCUITPY_NEOPIXEL_WRITE = 1
 CIRCUITPY_PULSEIO = 0
 CIRCUITPY_OS = 1
 CIRCUITPY_NVM = 0
@@ -31,7 +31,7 @@ CIRCUITPY_BITBANGIO = 1
 # Requires DigitalIO
 CIRCUITPY_GAMEPAD = 0
 # Requires neopixel_write or SPI (dotstar)
-CIRCUITPY_PIXELBUF = 0
+CIRCUITPY_PIXELBUF = 1
 # Requires OS
 CIRCUITPY_RANDOM = 1
 # Requires OS, filesystem

ports/broadcom/mphalport.c

@@ -6,7 +6,15 @@
 #include "shared-bindings/microcontroller/__init__.h"
 #include "mphalport.h"
 
+#include "peripherals/broadcom/defines.h"
+
 void mp_hal_delay_us(mp_uint_t delay) {
+    uint32_t end = SYSTMR->CLO + delay;
+    // Wait if end is before current time because it must have wrapped.
+    while (end < SYSTMR->CLO) {
+    }
+    while (SYSTMR->CLO < end) {
+    }
 }
 
 void mp_hal_disable_all_interrupts(void) {
@@ -19,6 +27,7 @@ void mp_hal_enable_all_interrupts(void) {
 
 mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs) {
     size_t sp = 0;
+    #if defined(__ARM_ARCH) && (__ARM_ARCH >= 8)
     __asm__ ("mov %[out], sp" : [out] "=r" (sp));
     __asm__ ("mov %[out], x19" : [out] "=r" (regs[0]));
     __asm__ ("mov %[out], x20" : [out] "=r" (regs[1]));
@@ -30,5 +39,19 @@ mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs) {
     __asm__ ("mov %[out], x26" : [out] "=r" (regs[7]));
     __asm__ ("mov %[out], x27" : [out] "=r" (regs[8]));
     __asm__ ("mov %[out], x28" : [out] "=r" (regs[9]));
+    #else
+    __asm__ ("mov %[out], sp" : [out] "=r" (sp));
+    __asm__ ("mov %[out], x19" : [out] "=r" (regs[0]));
+    __asm__ ("mov %[out], x20" : [out] "=r" (regs[1]));
+    __asm__ ("mov %[out], x21" : [out] "=r" (regs[2]));
+    __asm__ ("mov %[out], x22" : [out] "=r" (regs[3]));
+    __asm__ ("mov %[out], x23" : [out] "=r" (regs[4]));
+    __asm__ ("mov %[out], x24" : [out] "=r" (regs[5]));
+    __asm__ ("mov %[out], x25" : [out] "=r" (regs[6]));
+    __asm__ ("mov %[out], x26" : [out] "=r" (regs[7]));
+    __asm__ ("mov %[out], x27" : [out] "=r" (regs[8]));
+    __asm__ ("mov %[out], x28" : [out] "=r" (regs[9]));
+    #endif
+
     return sp;
 }

ports/broadcom/peripherals

@@ -1 +1 @@
-Subproject commit e136e387177446c3c9979bbf274a4856bf13797d
+Subproject commit 2c10889a4b2d78987bc4e0783db2e7584aa4d572