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Provide incoming HCI buffer for BTstack #2165

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Merged
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Jan 29, 2025
Merged

Provide incoming HCI buffer for BTstack #2165

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37 changes: 27 additions & 10 deletions src/rp2_common/pico_cyw43_driver/btstack_hci_transport_cyw43.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,21 +6,35 @@

#include "pico.h"
#include "cyw43.h"
#include "hci_transport.h"
#include "btstack_config.h"
#include "hci.h"
#include "hci_transport.h"
#include "pico/btstack_hci_transport_cyw43.h"
#include "pico/btstack_chipset_cyw43.h"

// cyw43_bluetooth_hci_write and cyw43_bluetooth_hci_read require a custom 4-byte packet header in front of the actual HCI packet
// the HCI packet type is stored in the fourth byte of the packet header
#define CYW43_PACKET_HEADER_SIZE 4

// assert outgoing pre-buffer for cyw43 header is available
#if !defined(HCI_OUTGOING_PRE_BUFFER_SIZE) || (HCI_OUTGOING_PRE_BUFFER_SIZE < 4)
#error HCI_OUTGOING_PRE_BUFFER_SIZE not defined or smaller than 4. Please update btstack_config.h
#if !defined(HCI_OUTGOING_PRE_BUFFER_SIZE) || (HCI_OUTGOING_PRE_BUFFER_SIZE < CYW43_PACKET_HEADER_SIZE)
#error HCI_OUTGOING_PRE_BUFFER_SIZE not defined or smaller than 4 (CYW43_PACKET_HEADER_SIZE) bytes. Please update btstack_config.h
#endif

// assert outgoing packet fragments are word aligned
#if !defined(HCI_ACL_CHUNK_SIZE_ALIGNMENT) || ((HCI_ACL_CHUNK_SIZE_ALIGNMENT & 3) != 0)
#error HCI_ACL_CHUNK_SIZE_ALIGNMENT not defined or not a multiply of 4. Please update btstack_config.h
#error HCI_ACL_CHUNK_SIZE_ALIGNMENT not defined or not a multiple of 4. Please update btstack_config.h
#endif

// ensure incoming pre-buffer for cyw43 header is available (defaults from btstack/src/hci.h)
#if HCI_INCOMING_PRE_BUFFER_SIZE < CYW43_PACKET_HEADER_SIZE
#undef HCI_INCOMING_PRE_BUFFER_SIZE
#define HCI_INCOMING_PRE_BUFFER_SIZE CYW43_PACKET_HEADER_SIZE
#endif

// ensure buffer for cyw43_bluetooth_hci_read starts word aligned (word align pre buffer)
#define HCI_INCOMING_PRE_BUFFER_SIZE_ALIGNED ((HCI_INCOMING_PRE_BUFFER_SIZE + 3) & ~3)

#define BT_DEBUG_ENABLED 0
#if BT_DEBUG_ENABLED
#define BT_DEBUG(...) CYW43_PRINTF(__VA_ARGS__)
Expand All @@ -31,9 +45,12 @@
// Callback when we have data
static void (*hci_transport_cyw43_packet_handler)(uint8_t packet_type, uint8_t *packet, uint16_t size) = NULL;

// Incoming packet buffer - cyw43 packet header (incl packet type) + incoming pre buffer + max(acl header + acl payload, event header + event data)
// The incoming packet buffer consist of a pre-buffer and the actual HCI packet
// For the call to cyw43_bluetooth_hci_read, the last 4 bytes (CY43_PACKET_HEADER_SIZE) of the pre-buffer is used for the CYW43 packet header
// After that, only the actual HCI packet is forwarded to BTstack, which expects HCI_INCOMING_PACKET_BUFFER_SIZE of pre-buffer bytes for its own use.
__attribute__((aligned(4)))
static uint8_t hci_packet_with_pre_buffer[4 + HCI_INCOMING_PRE_BUFFER_SIZE + HCI_INCOMING_PACKET_BUFFER_SIZE ];
static uint8_t hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE_ALIGNED + HCI_INCOMING_PACKET_BUFFER_SIZE ];
static uint8_t * cyw43_receive_buffer = &hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE_ALIGNED - CYW43_PACKET_HEADER_SIZE];

static btstack_data_source_t transport_data_source;
static bool hci_transport_ready;
Expand Down Expand Up @@ -97,8 +114,8 @@ static int hci_transport_cyw43_can_send_now(uint8_t packet_type) {
static int hci_transport_cyw43_send_packet(uint8_t packet_type, uint8_t *packet, int size) {
// store packet type before actual data and increase size
// This relies on HCI_OUTGOING_PRE_BUFFER_SIZE being set
uint8_t *buffer = &packet[-4];
uint32_t buffer_size = size + 4;
uint8_t *buffer = &packet[-CYW43_PACKET_HEADER_SIZE];
uint32_t buffer_size = size + CYW43_PACKET_HEADER_SIZE;
buffer[3] = packet_type;

CYW43_THREAD_ENTER
Expand Down Expand Up @@ -143,10 +160,10 @@ static void hci_transport_cyw43_process(void) {
uint32_t loop_count = 0;
#endif
do {
int err = cyw43_bluetooth_hci_read(hci_packet_with_pre_buffer, sizeof(hci_packet_with_pre_buffer), &len);
int err = cyw43_bluetooth_hci_read(cyw43_receive_buffer, CYW43_PACKET_HEADER_SIZE + HCI_INCOMING_PACKET_BUFFER_SIZE , &len);
BT_DEBUG("bt in len=%lu err=%d\n", len, err);
if (err == 0 && len > 0) {
hci_transport_cyw43_packet_handler(hci_packet_with_pre_buffer[3], hci_packet_with_pre_buffer + 4, len - 4);
hci_transport_cyw43_packet_handler(cyw43_receive_buffer[3], &cyw43_receive_buffer[CYW43_PACKET_HEADER_SIZE], len - CYW43_PACKET_HEADER_SIZE);
has_work = true;
} else {
has_work = false;
Expand Down
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