esp32/boards: Add GENERIC_C3_USB board with USB serial/JTAG support.

Add a new board type for ESP32-C3 revision 3 and up that implement the USB
serial/JTAG port on pin 18 and 19.  This variant uses the USB serial for
programming and console, leaving the UART free.

- Pins 18 and 19 are correctly reserved for this variant.  Also pins 14-17
  are reserved for flash for any ESP32-C3 so they can't be reconfigured
  anymore to crash the system.
- Added usb_serial_jtag.c and .h to implement this interface.
- Interface was tested to work correctly together with webrepl.
- Interface was tested to work correctly when sending and receiving
  large files with ampy.
- Disconnecting terminal or USB will not hang the system when it's
  trying to print.

9 files changed, 174 insertions, 4 deletions

diff --git a/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.cmake b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.cmake
new file mode 100644
index 000000000..2b65121b9
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.cmake
@@ -0,0 +1,11 @@
+set(IDF_TARGET esp32c3)
+
+set(SDKCONFIG_DEFAULTS
+    boards/sdkconfig.base
+    boards/sdkconfig.ble
+    boards/GENERIC_C3_USB/sdkconfig.board
+)
+
+if(NOT MICROPY_FROZEN_MANIFEST)
+    set(MICROPY_FROZEN_MANIFEST ${MICROPY_PORT_DIR}/boards/manifest.py)
+endif()
diff --git a/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.h b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.h
new file mode 100644
index 000000000..d403e70e4
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3_USB/mpconfigboard.h
@@ -0,0 +1,8 @@
+// This configuration is for a generic ESP32C3 board with 4MiB (or more) of flash.
+
+#define MICROPY_HW_BOARD_NAME               "ESP32C3 module"
+#define MICROPY_HW_MCU_NAME                 "ESP32C3"
+
+#define MICROPY_HW_ENABLE_SDCARD            (0)
+#define MICROPY_PY_MACHINE_DAC              (0)
+#define MICROPY_PY_MACHINE_I2S              (0)
diff --git a/ports/esp32/boards/GENERIC_C3_USB/sdkconfig.board b/ports/esp32/boards/GENERIC_C3_USB/sdkconfig.board
new file mode 100644
index 000000000..f0cbad00e
--- /dev/null
+++ b/ports/esp32/boards/GENERIC_C3_USB/sdkconfig.board
@@ -0,0 +1,9 @@
+CONFIG_ESP32C3_REV_MIN_3=y
+CONFIG_ESP32C3_REV_MIN=3
+CONFIG_ESP32C3_BROWNOUT_DET=y
+CONFIG_ESP32C3_BROWNOUT_DET_LVL_SEL_7=
+CONFIG_ESP32C3_BROWNOUT_DET_LVL_SEL_4=y
+CONFIG_ESP32C3_BROWNOUT_DET_LVL=4
+CONFIG_ESP_CONSOLE_UART_DEFAULT=
+CONFIG_ESP_CONSOLE_USB_CDC=
+CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG=y
diff --git a/ports/esp32/machine_pin.c b/ports/esp32/machine_pin.c
index 181f88b78..6c1e96879 100644
--- a/ports/esp32/machine_pin.c
+++ b/ports/esp32/machine_pin.c
@@ -125,12 +125,17 @@ STATIC const machine_pin_obj_t machine_pin_obj[] = {
     {{&machine_pin_type}, GPIO_NUM_11},
     {{&machine_pin_type}, GPIO_NUM_12},
     {{&machine_pin_type}, GPIO_NUM_13},
-    {{&machine_pin_type}, GPIO_NUM_14},
-    {{&machine_pin_type}, GPIO_NUM_15},
-    {{&machine_pin_type}, GPIO_NUM_16},
-    {{&machine_pin_type}, GPIO_NUM_17},
+    {{NULL}, -1}, // 14 FLASH
+    {{NULL}, -1}, // 15 FLASH
+    {{NULL}, -1}, // 16 FLASH
+    {{NULL}, -1}, // 17 FLASH
+    #if CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+    {{NULL}, -1}, // 18 is for native USB D-
+    {{NULL}, -1}, // 19 is for native USB D+
+    #else
     {{&machine_pin_type}, GPIO_NUM_18},
     {{&machine_pin_type}, GPIO_NUM_19},
+    #endif
     {{&machine_pin_type}, GPIO_NUM_20},
     {{&machine_pin_type}, GPIO_NUM_21},
 
diff --git a/ports/esp32/main.c b/ports/esp32/main.c
index 0650c8d71..2ba613668 100644
--- a/ports/esp32/main.c
+++ b/ports/esp32/main.c
@@ -58,6 +58,7 @@
 #include "shared/runtime/pyexec.h"
 #include "uart.h"
 #include "usb.h"
+#include "usb_serial_jtag.h"
 #include "modmachine.h"
 #include "modnetwork.h"
 #include "mpthreadport.h"
@@ -89,6 +90,8 @@ void mp_task(void *pvParameter) {
     #endif
     #if CONFIG_USB_ENABLED
     usb_init();
+    #elif CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+    usb_serial_jtag_init();
     #else
     uart_init();
     #endif
diff --git a/ports/esp32/main/CMakeLists.txt b/ports/esp32/main/CMakeLists.txt
index 0e7d6ff25..057ec0244 100644
--- a/ports/esp32/main/CMakeLists.txt
+++ b/ports/esp32/main/CMakeLists.txt
@@ -47,6 +47,7 @@ set(MICROPY_SOURCE_PORT
     ${PROJECT_DIR}/main.c
     ${PROJECT_DIR}/uart.c
     ${PROJECT_DIR}/usb.c
+    ${PROJECT_DIR}/usb_serial_jtag.c
     ${PROJECT_DIR}/gccollect.c
     ${PROJECT_DIR}/mphalport.c
     ${PROJECT_DIR}/fatfs_port.c
diff --git a/ports/esp32/mphalport.c b/ports/esp32/mphalport.c
index 6e6fd26ef..de1b173ac 100644
--- a/ports/esp32/mphalport.c
+++ b/ports/esp32/mphalport.c
@@ -53,6 +53,7 @@
 #include "shared/runtime/pyexec.h"
 #include "mphalport.h"
 #include "usb.h"
+#include "usb_serial_jtag.h"
 
 TaskHandle_t mp_main_task_handle;
 
@@ -118,6 +119,8 @@ void mp_hal_stdout_tx_strn(const char *str, size_t len) {
     }
     #if CONFIG_USB_ENABLED
     usb_tx_strn(str, len);
+    #elif CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+    usb_serial_jtag_tx_strn(str, len);
     #else
     for (uint32_t i = 0; i < len; ++i) {
         uart_tx_one_char(str[i]);
diff --git a/ports/esp32/usb_serial_jtag.c b/ports/esp32/usb_serial_jtag.c
new file mode 100644
index 000000000..a7d06a355
--- /dev/null
+++ b/ports/esp32/usb_serial_jtag.c
@@ -0,0 +1,98 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Patrick Van Oosterwijck
+ *
+ * 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 "py/runtime.h"
+#include "py/mphal.h"
+#include "usb_serial_jtag.h"
+
+#if CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
+
+#include "hal/usb_serial_jtag_ll.h"
+#include "esp_intr_alloc.h"
+#include "soc/periph_defs.h"
+
+#define USB_SERIAL_JTAG_BUF_SIZE (64)
+
+static uint8_t rx_buf[USB_SERIAL_JTAG_BUF_SIZE];
+static volatile bool terminal_connected = false;
+
+static void usb_serial_jtag_isr_handler(void *arg) {
+    uint32_t flags = usb_serial_jtag_ll_get_intsts_mask();
+
+    if (flags & USB_SERIAL_JTAG_INTR_SOF) {
+        usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_INTR_SOF);
+    }
+
+    if (flags & USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT) {
+        usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT);
+        size_t req_len = ringbuf_free(&stdin_ringbuf);
+        if (req_len > USB_SERIAL_JTAG_BUF_SIZE) {
+            req_len = USB_SERIAL_JTAG_BUF_SIZE;
+        }
+        size_t len = usb_serial_jtag_ll_read_rxfifo(rx_buf, req_len);
+        for (size_t i = 0; i < len; ++i) {
+            if (rx_buf[i] == mp_interrupt_char) {
+                mp_sched_keyboard_interrupt();
+            } else {
+                ringbuf_put(&stdin_ringbuf, rx_buf[i]);
+            }
+        }
+        mp_hal_wake_main_task_from_isr();
+    }
+}
+
+void usb_serial_jtag_init(void) {
+    usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT |
+        USB_SERIAL_JTAG_INTR_SOF);
+    usb_serial_jtag_ll_ena_intr_mask(USB_SERIAL_JTAG_INTR_SERIAL_OUT_RECV_PKT |
+        USB_SERIAL_JTAG_INTR_SOF);
+    ESP_ERROR_CHECK(esp_intr_alloc(ETS_USB_SERIAL_JTAG_INTR_SOURCE, ESP_INTR_FLAG_LEVEL1,
+        usb_serial_jtag_isr_handler, NULL, NULL));
+}
+
+void usb_serial_jtag_tx_strn(const char *str, size_t len) {
+    while (len) {
+        size_t l = len;
+        if (l > USB_SERIAL_JTAG_PACKET_SZ_BYTES) {
+            l = USB_SERIAL_JTAG_PACKET_SZ_BYTES;
+        }
+        portTickType start_tick = xTaskGetTickCount();
+        while (!usb_serial_jtag_ll_txfifo_writable()) {
+            portTickType now_tick = xTaskGetTickCount();
+            if (!terminal_connected || now_tick > (start_tick + pdMS_TO_TICKS(200))) {
+                terminal_connected = false;
+                return;
+            }
+        }
+        terminal_connected = true;
+        l = usb_serial_jtag_ll_write_txfifo((const uint8_t *)str, l);
+        usb_serial_jtag_ll_txfifo_flush();
+        str += l;
+        len -= l;
+    }
+}
+
+#endif // CONFIG_ESP_CONSOLE_USB_SERIAL_JTAG
diff --git a/ports/esp32/usb_serial_jtag.h b/ports/esp32/usb_serial_jtag.h
new file mode 100644
index 000000000..4eebb19e4
--- /dev/null
+++ b/ports/esp32/usb_serial_jtag.h
@@ -0,0 +1,32 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2021 Patrick Van Oosterwijck
+ *
+ * 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.
+ */
+#ifndef MICROPY_INCLUDED_ESP32_USB_SERIAL_JTAG_H
+#define MICROPY_INCLUDED_ESP32_USB_SERIAL_JTAG_H
+
+void usb_serial_jtag_init(void);
+void usb_serial_jtag_tx_strn(const char *str, size_t len);
+
+#endif // MICROPY_INCLUDED_ESP32_USB_SERIAL_JTAG_H