Add floppyio

Initially enabled for samd51, this enables reading raw flux data as well
as DOS/MFM formatted media.

This is only the low-level code for reading & decoding flux pulses from a floppy drive.
high level details will live in a Python library.

adafruit-circuitpython-floppy will take care of details like stepping
from track to track, etc.

.gitmodules

@@ -199,3 +199,6 @@
 	url = https://github.com/raspberrypi/rpi-firmware.git
 	branch = master
 	shallow = true
+[submodule "lib/adafruit_floppy"]
+	path = lib/adafruit_floppy
+	url = https://github.com/adafruit/Adafruit_Floppy

lib/adafruit_floppy

@@ -0,0 +1 @@
+Subproject commit d5d34127db8167b7a6aca8045d27f6b9e3930c6d

ports/atmel-samd/common-hal/floppyio/__init__.h

@@ -0,0 +1,30 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2022 Jeff Epler 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.
+ */
+
+#pragma once
+
+// empirical-ish from Arduino @ 120MHz
+#define FLOPPYIO_SAMPLERATE (14666667)

ports/atmel-samd/mpconfigport.mk

@@ -87,6 +87,7 @@ CIRCUITPY_TOUCHIO_USE_NATIVE = 0
 CIRCUITPY_ALARM ?= 1
 CIRCUITPY_PS2IO ?= 1
 CIRCUITPY_SAMD ?= 1
+CIRCUITPY_FLOPPYIO ?= 1
 CIRCUITPY_FRAMEBUFFERIO ?= $(CIRCUITPY_FULL_BUILD)
 CIRCUITPY_RGBMATRIX ?= $(CIRCUITPY_FRAMEBUFFERIO)
 CIRCUITPY_WATCHDOG ?= 1
@@ -107,6 +108,7 @@ CIRCUITPY_TOUCHIO_USE_NATIVE = 0
 CIRCUITPY_ALARM ?= 1
 CIRCUITPY_PS2IO ?= 1
 CIRCUITPY_SAMD ?= 1
+CIRCUITPY_FLOPPYIO ?= 1
 CIRCUITPY_FRAMEBUFFERIO ?= $(CIRCUITPY_FULL_BUILD)
 CIRCUITPY_RGBMATRIX ?= $(CIRCUITPY_FRAMEBUFFERIO)
 

py/circuitpy_defns.mk

@@ -164,6 +164,9 @@ endif
 ifeq ($(CIRCUITPY_VECTORIO),1)
 SRC_PATTERNS += vectorio/%
 endif
+ifeq ($(CIRCUITPY_FLOPPYIO),1)
+SRC_PATTERNS += floppyio/%
+endif
 ifeq ($(CIRCUITPY_FRAMEBUFFERIO),1)
 SRC_PATTERNS += framebufferio/%
 endif
@@ -526,6 +529,7 @@ SRC_SHARED_MODULE_ALL = \
 	displayio/TileGrid.c \
 	displayio/area.c \
 	displayio/__init__.c \
+	floppyio/__init__.c \
 	fontio/BuiltinFont.c \
 	fontio/__init__.c \
 	framebufferio/FramebufferDisplay.c \

py/circuitpy_mpconfig.mk

@@ -219,6 +219,9 @@ CFLAGS += -DCIRCUITPY_ESPIDF=$(CIRCUITPY_ESPIDF)
 CIRCUITPY__EVE ?= 0
 CFLAGS += -DCIRCUITPY__EVE=$(CIRCUITPY__EVE)
 
+CIRCUITPY_FLOPPYIO ?= 0
+CFLAGS += -DCIRCUITPY_FLOPPYIO=$(CIRCUITPY_FLOPPYIO)
+
 CIRCUITPY_FREQUENCYIO ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_FREQUENCYIO=$(CIRCUITPY_FREQUENCYIO)
 

shared-bindings/floppyio/__init__.c

@@ -0,0 +1,128 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2022 Jeff Epler 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/floppyio/__init__.h"
+#include "shared-bindings/digitalio/DigitalInOut.h"
+#include "common-hal/floppyio/__init__.h"
+
+#include <stdint.h>
+
+#include "py/binary.h"
+#include "py/enum.h"
+#include "py/obj.h"
+#include "py/runtime.h"
+
+//| def flux_readinto(buffer: WriteableBuffer, data: DigitalInOut, index: DigitalInOut) -> int:
+//|     """Read flux transition information into the buffer.
+//|
+//|     The function returns when the buffer has filled, or when the index input
+//|     indicates that one full revolution of data has been recorded.  Due to
+//|     technical limitations, this process may not be interruptible by
+//|     KeyboardInterrupt.
+//|
+//|     :param buffer: Read data into this buffer.  Each element represents the time between successive zero-to-one transitions.
+//|     :param data: Pin on which the flux data appears
+//|     :param index: Pin on which the index pulse appears
+//|     :return: The actual number of bytes of read
+//|     """
+//|     ...
+//|
+STATIC mp_obj_t floppyio_flux_readinto(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_buffer, ARG_data, ARG_index };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_buffer, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_data, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_index, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[ARG_buffer].u_obj, &bufinfo, MP_BUFFER_WRITE);
+    digitalio_digitalinout_obj_t *data = assert_digitalinout(args[ARG_data].u_obj);
+    digitalio_digitalinout_obj_t *index = assert_digitalinout(args[ARG_index].u_obj);
+
+    return MP_OBJ_NEW_SMALL_INT(common_hal_floppyio_flux_readinto(bufinfo.buf, bufinfo.len, data, index));
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(floppyio_flux_readinto_obj, 0, floppyio_flux_readinto);
+
+//| def mfm_readinto(buffer: WriteableBuffer, data: DigitalInOut, index: DigitalInOut) -> int:
+//|     """Read mfm blocks into the buffer.
+//|
+//|     The track is assumed to consist of 512-byte sectors.
+//|
+//|     The function returns when all sectors have been successfully read, or
+//|     a number of index pulses have occurred.  Due to technical limitations, this
+//|     process may not be interruptible by KeyboardInterrupt.
+//|
+//|     :param buffer: Read data into this buffer.  Must be a multiple of 512.
+//|     :param data: Pin on which the mfm data appears
+//|     :param index: Pin on which the index pulse appears
+//|     :return: The actual number of sectors read
+//|     """
+//|     ...
+//|
+STATIC mp_obj_t floppyio_mfm_readinto(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    enum { ARG_buffer, ARG_data, ARG_index };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_buffer, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_data, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_index, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    mp_buffer_info_t bufinfo;
+    mp_get_buffer_raise(args[ARG_buffer].u_obj, &bufinfo, MP_BUFFER_WRITE);
+    digitalio_digitalinout_obj_t *data = assert_digitalinout(args[ARG_data].u_obj);
+    digitalio_digitalinout_obj_t *index = assert_digitalinout(args[ARG_index].u_obj);
+
+    if (bufinfo.len % 512 != 0) {
+        mp_raise_ValueError(translate("Buffer must be a multiple of 512 bytes"));
+    }
+    size_t n_sectors = bufinfo.len / 512;
+    return MP_OBJ_NEW_SMALL_INT(common_hal_floppyio_mfm_readinto(bufinfo.buf, n_sectors, data, index));
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(floppyio_mfm_readinto_obj, 0, floppyio_mfm_readinto);
+
+//| samplerate: int
+//| """The approximate sample rate in Hz used by flux_readinto."""
+//|
+
+STATIC const mp_rom_map_elem_t floppyio_module_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_floppyio) },
+    { MP_ROM_QSTR(MP_QSTR_flux_readinto), MP_ROM_PTR(&floppyio_flux_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_mfm_readinto), MP_ROM_PTR(&floppyio_mfm_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_samplerate), MP_ROM_INT(FLOPPYIO_SAMPLERATE) },
+};
+STATIC MP_DEFINE_CONST_DICT(floppyio_module_globals, floppyio_module_globals_table);
+
+const mp_obj_module_t floppyio_module = {
+    .base = {&mp_type_module },
+    .globals = (mp_obj_dict_t *)&floppyio_module_globals,
+};
+
+MP_REGISTER_MODULE(MP_QSTR_floppyio, floppyio_module, CIRCUITPY_FLOPPYIO);

shared-bindings/floppyio/__init__.h

@@ -0,0 +1,32 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2022 Jeff Epler 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.
+ */
+
+#pragma once
+
+#include "common-hal/digitalio/DigitalInOut.h"
+
+int common_hal_floppyio_flux_readinto(void *buf, size_t len, digitalio_digitalinout_obj_t *data, digitalio_digitalinout_obj_t *index);
+int common_hal_floppyio_mfm_readinto(void *buf, size_t n_sector, digitalio_digitalinout_obj_t *data, digitalio_digitalinout_obj_t *index);

shared-module/floppyio/__init__.c

@@ -0,0 +1,108 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2022 Jeff Epler 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 "hal_gpio.h"
+
+#include "py/runtime.h"
+
+#include "shared-bindings/time/__init__.h"
+#include "shared-bindings/floppyio/__init__.h"
+#include "common-hal/floppyio/__init__.h"
+#include "shared-bindings/digitalio/DigitalInOut.h"
+
+#define T2_5 (FLOPPYIO_SAMPLERATE * 5 / 2 / 1000000)
+#define T3_5 (FLOPPYIO_SAMPLERATE * 7 / 2 / 1000000)
+
+#define MFM_IO_MMIO (1)
+#include "lib/adafruit_floppy/mfm_impl.h"
+
+__attribute__((optimize("O3")))
+int common_hal_floppyio_flux_readinto(void *buf, size_t len, digitalio_digitalinout_obj_t *data, digitalio_digitalinout_obj_t *index) {
+    uint32_t index_mask;
+    volatile uint32_t *index_port = common_hal_digitalio_digitalinout_get_reg(index, DIGITALINOUT_REG_READ, &index_mask);
+
+    uint32_t data_mask;
+    volatile uint32_t *data_port = common_hal_digitalio_digitalinout_get_reg(data, DIGITALINOUT_REG_READ, &data_mask);
+
+#undef READ_INDEX
+#undef READ_DATA
+#define READ_INDEX() (!!(*index_port & index_mask))
+#define READ_DATA() (!!(*data_port & data_mask))
+
+    memset(buf, 0, len);
+
+    uint8_t *pulses = buf, *pulses_ptr = pulses, *pulses_end = pulses + len;
+
+    common_hal_mcu_disable_interrupts();
+
+    // wait for index pulse low
+    while (READ_INDEX()) { /* NOTHING */
+    }
+
+
+    // if data line is low, wait till it rises
+    while (!READ_DATA()) { /* NOTHING */
+    }
+
+    // and then till it drops down
+    while (READ_DATA()) { /* NOTHING */
+    }
+
+    uint32_t index_state = 0;
+    while (pulses_ptr < pulses_end) {
+        index_state = (index_state << 1) | READ_INDEX();
+        if ((index_state & 3) == 2) { // a zero-to-one transition
+            break;
+        }
+
+        unsigned pulse_count = 3;
+        while (!READ_DATA()) {
+            pulse_count++;
+        }
+
+        while (READ_DATA()) {
+            pulse_count++;
+        }
+
+        *pulses_ptr++ = MIN(255, pulse_count);
+    }
+    common_hal_mcu_enable_interrupts();
+
+    return pulses_ptr - pulses;
+}
+
+int common_hal_floppyio_mfm_readinto(void *buf, size_t n_sectors, digitalio_digitalinout_obj_t *data, digitalio_digitalinout_obj_t *index) {
+    mfm_io_t io;
+    io.index_port = common_hal_digitalio_digitalinout_get_reg(index, DIGITALINOUT_REG_READ, &io.index_mask);
+    io.data_port = common_hal_digitalio_digitalinout_get_reg(data, DIGITALINOUT_REG_READ, &io.data_mask);
+
+    common_hal_mcu_disable_interrupts();
+    uint8_t validity[n_sectors];
+    int result = read_track(io, n_sectors, buf, validity);
+    common_hal_mcu_enable_interrupts();
+
+    return result;
+}