pbio/drv/usb: Add common driver. #410
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| // SPDX-License-Identifier: MIT | ||
| // Copyright (c) 2025 The Pybricks Authors | ||
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| #include <pbdrv/config.h> | ||
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| #if PBDRV_CONFIG_USB | ||
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| #include <errno.h> | ||
| #include <signal.h> | ||
| #include <stdio.h> | ||
| #include <stdlib.h> | ||
| #include <unistd.h> | ||
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| #include "usb.h" | ||
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| #include <pbdrv/config.h> | ||
| #include <pbdrv/usb.h> | ||
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| #include <pbio/error.h> | ||
| #include <pbio/os.h> | ||
| #include <pbio/protocol.h> | ||
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| #include <lwrb/lwrb.h> | ||
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| /** | ||
| * Host is subscribed to our outgoing event messages. | ||
| */ | ||
| static bool pbdrv_usb_events_subscribed; | ||
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| bool pbdrv_usb_connection_is_active(void) { | ||
| return pbdrv_usb_events_subscribed && pbdrv_usb_is_ready(); | ||
| } | ||
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| /** | ||
| * Pybricks system command handler. | ||
| */ | ||
| static pbdrv_usb_receive_handler_t pbdrv_usb_receive_handler; | ||
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| void pbdrv_usb_set_receive_handler(pbdrv_usb_receive_handler_t handler) { | ||
| pbdrv_usb_receive_handler = handler; | ||
| } | ||
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| /** | ||
| * Buffer scheduled status. | ||
| */ | ||
| static uint8_t status_data[PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE]; | ||
| static bool status_data_pending; | ||
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| void pbdrv_usb_schedule_status_update(const uint8_t *status_msg) { | ||
| // Ignore if message identical to last. | ||
| if (!memcmp(status_data, status_msg, sizeof(status_data))) { | ||
| return; | ||
| } | ||
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| // Schedule to send whenever the Bluetooth process gets round to it. | ||
| memcpy(status_data, status_msg, sizeof(status_data)); | ||
| status_data_pending = true; | ||
| pbio_os_request_poll(); | ||
| } | ||
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| /** | ||
| * Buffer for scheduled stdout. | ||
| */ | ||
| static lwrb_t stdout_ring_buf; | ||
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| pbio_error_t pbdrv_usb_stdout_tx(const uint8_t *data, uint32_t *size) { | ||
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| if (!pbdrv_usb_connection_is_active()) { | ||
| return PBIO_ERROR_INVALID_OP; | ||
| } | ||
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| // Buffer data to send it more efficiently even if the caller is only | ||
| // writing one byte at a time. | ||
| if ((*size = lwrb_write(&stdout_ring_buf, data, *size)) == 0) { | ||
| return PBIO_ERROR_AGAIN; | ||
| } | ||
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| // Poke the process to start tx soon-ish. This way, we can accumulate | ||
| // data bytes before actually transmitting. | ||
| pbio_os_request_poll(); | ||
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| return PBIO_SUCCESS; | ||
| } | ||
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| uint32_t pbdrv_usb_stdout_tx_available(void) { | ||
| if (!pbdrv_usb_connection_is_active()) { | ||
| return UINT32_MAX; | ||
| } | ||
| return lwrb_get_free(&stdout_ring_buf); | ||
| } | ||
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| bool pbdrv_usb_stdout_tx_is_idle(void) { | ||
| if (!pbdrv_usb_connection_is_active()) { | ||
| return true; | ||
| } | ||
| return lwrb_get_full(&stdout_ring_buf) == 0; | ||
| } | ||
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| static bool respond_soon; | ||
| static pbio_pybricks_error_t respond_result; | ||
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| /** | ||
| * Non-blocking poll handler to process pending incoming messages. | ||
| */ | ||
| static void pbdrv_usb_handle_data_in(void) { | ||
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| // Ignore incoming data if we haven't sent our previous response yet. | ||
| if (respond_soon) { | ||
| return; | ||
| } | ||
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| static uint8_t data_in[PBDRV_CONFIG_USB_MAX_PACKET_SIZE]; | ||
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| uint32_t size = pbdrv_usb_get_data_in(data_in); | ||
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| // Expecting at least EP_MSG and payload. | ||
| if (size < 2) { | ||
| return; | ||
| } | ||
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| switch (data_in[0]) { | ||
| case PBIO_PYBRICKS_OUT_EP_MSG_SUBSCRIBE: | ||
| pbdrv_usb_events_subscribed = data_in[1]; | ||
| respond_result = PBIO_PYBRICKS_ERROR_OK; | ||
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| respond_soon = true; | ||
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| // Schedule sending current status immediately after subscribing. | ||
| status_data_pending = true; | ||
| break; | ||
| case PBIO_PYBRICKS_OUT_EP_MSG_COMMAND: | ||
| if (pbdrv_usb_receive_handler) { | ||
| respond_result = pbdrv_usb_receive_handler(data_in + 1, size - 1); | ||
| respond_soon = true; | ||
| } | ||
| break; | ||
| } | ||
| } | ||
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| static void pbdrv_usb_reset_state(void) { | ||
| pbdrv_usb_events_subscribed = false; | ||
| respond_soon = false; | ||
| status_data_pending = false; | ||
| lwrb_reset(&stdout_ring_buf); | ||
| } | ||
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| static pbio_os_process_t pbdrv_usb_process; | ||
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| static pbio_error_t pbdrv_usb_process_thread(pbio_os_state_t *state, void *context) { | ||
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| static pbio_os_state_t sub; | ||
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| static uint8_t *out_data; | ||
| static uint32_t out_size; | ||
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| pbio_error_t err; | ||
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| // Runs every time. If there is no connection, there just won't be data. | ||
| pbdrv_usb_handle_data_in(); | ||
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| PBIO_OS_ASYNC_BEGIN(state); | ||
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| for (;;) { | ||
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| // Run charger detection: wait for USB to become physically plugged in. | ||
| PBIO_OS_AWAIT(state, &sub, err = pbdrv_usb_wait_for_charger(&sub)); | ||
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| while (pbdrv_usb_process.request != PBIO_OS_PROCESS_REQUEST_TYPE_CANCEL && pbdrv_usb_is_ready()) { | ||
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| // Find out what we should send, if anything, priotizing response, then | ||
| // status, then stdout, then other events. | ||
| if (respond_soon) { | ||
| // Pack the response to the most recent message. | ||
| pbdrv_usb_tx_get_buf(PBIO_PYBRICKS_IN_EP_MSG_RESPONSE, &out_data); | ||
| pbio_set_uint32_le(&out_data[1], respond_result); | ||
| out_size = sizeof(uint32_t) + 1; | ||
| respond_soon = false; | ||
| } else if (pbdrv_usb_connection_is_active() && status_data_pending) { | ||
| // Send out status if pending (already includes event code). | ||
| pbdrv_usb_tx_get_buf(PBIO_PYBRICKS_IN_EP_MSG_EVENT, &out_data); | ||
| memcpy(&out_data[1], status_data, PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE); | ||
| out_size = PBIO_PYBRICKS_USB_MESSAGE_SIZE(PBIO_PYBRICKS_EVENT_STATUS_REPORT_SIZE); | ||
| status_data_pending = false; | ||
| } else if (pbdrv_usb_connection_is_active() && lwrb_get_full(&stdout_ring_buf) != 0) { | ||
| // Send out stdout if anything is buffered. | ||
| uint32_t max_size = pbdrv_usb_tx_get_buf(PBIO_PYBRICKS_IN_EP_MSG_EVENT, &out_data); | ||
| out_data[1] = PBIO_PYBRICKS_EVENT_WRITE_STDOUT; | ||
| out_size = lwrb_read(&stdout_ring_buf, &out_data[2], max_size - 2) + 2; | ||
| } | ||
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| // If there was anything to send, send it. | ||
| if (out_size) { | ||
| PBIO_OS_AWAIT(state, &sub, err = pbdrv_usb_tx(&sub, out_data, out_size)); | ||
| out_size = 0; | ||
| if (err != PBIO_SUCCESS) { | ||
| pbdrv_usb_reset_state(); | ||
| PBIO_OS_AWAIT(state, &sub, pbdrv_usb_tx_reset(&sub)); | ||
| } | ||
| } else { | ||
| // Otherwise yield once before going and check again. | ||
| PBIO_OS_AWAIT_ONCE(state); | ||
| } | ||
| } | ||
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| PBIO_OS_AWAIT_WHILE(state, pbdrv_usb_is_ready()); | ||
| pbdrv_usb_reset_state(); | ||
| pbdrv_usb_tx_reset(&sub); | ||
| } | ||
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| // Unreachable. On cancellation, the charger detection step in the above | ||
| // loop keeps running. It will just skip the data handler. | ||
| PBIO_OS_ASYNC_END(PBIO_ERROR_FAILED); | ||
| } | ||
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| void pbdrv_usb_init(void) { | ||
| pbdrv_usb_init_device(); | ||
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| static uint8_t stdout_buf[PBDRV_CONFIG_USB_MAX_PACKET_SIZE * 2]; | ||
| lwrb_init(&stdout_ring_buf, stdout_buf, PBIO_ARRAY_SIZE(stdout_buf)); | ||
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| pbio_os_process_start(&pbdrv_usb_process, pbdrv_usb_process_thread, NULL); | ||
| } | ||
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| void pbdrv_usb_deinit(void) { | ||
| pbdrv_usb_deinit_device(); | ||
| pbio_os_process_make_request(&pbdrv_usb_process, PBIO_OS_PROCESS_REQUEST_TYPE_CANCEL); | ||
| } | ||
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| #endif // PBDRV_CONFIG_USB | ||
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It doesn't look like there is anything hardware-specific here, it would make more sense to me to have this new layer be
pbsysinstead ofpbdrv. (Kind of like BlueZ manages the Bluetooth stack on Linux at the OS level doing most of it in userspace and only calls into the kernel to actually poke the hardware).There was a problem hiding this comment.
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Yeah, the same probably goes for the newly structured Bluetooth drivers. It could benefit from some renaming too to make it a bit more consistent with its USB counterpart.
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Going to leave this for a future update since
pbsysstarts a bit later. We should be fine but it means that the receive handlers get set up slightly later, so deserves a closer look.