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Add a USB message queue to USB to CANbus bridge code #6354

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merged 3 commits into from
Oct 4, 2023
Merged

Add a USB message queue to USB to CANbus bridge code #6354

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5b20486
usb_canbus: Rename UsbCan.queue to UsbCan.canhw_queue
KevinOConnor Sep 25, 2023
78ae83c
usb_canbus: Add a local queue for USB messages received from host
KevinOConnor Sep 25, 2023
6adff39
usb_canbus: Prioritize local response sending over new host messages
KevinOConnor Sep 26, 2023
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87 changes: 56 additions & 31 deletions src/generic/usb_canbus.c
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Original file line number Diff line number Diff line change
Expand Up @@ -104,20 +104,18 @@ struct gs_host_frame {
static struct usbcan_data {
struct task_wake wake;

// Canbus data from host
union {
struct gs_host_frame host_frame;
uint8_t rx_frame_pad[USB_CDC_EP_BULK_OUT_SIZE];
};
uint8_t host_status;

// Canbus data routed locally
uint8_t notify_local, usb_send_busy;
uint32_t assigned_id;

// Canbus data from host
uint8_t host_status;
uint32_t host_pull_pos, host_push_pos;
struct gs_host_frame host_frames[16];

// Data from physical canbus interface
uint32_t pull_pos, push_pos;
struct canbus_msg queue[32];
uint32_t canhw_pull_pos, canhw_push_pos;
struct canbus_msg canhw_queue[32];
} UsbCan;

enum {
Expand All @@ -139,16 +137,16 @@ void
canbus_process_data(struct canbus_msg *msg)
{
// Add to admin command queue
uint32_t pushp = UsbCan.push_pos;
if (pushp - UsbCan.pull_pos >= ARRAY_SIZE(UsbCan.queue))
uint32_t pushp = UsbCan.canhw_push_pos;
if (pushp - UsbCan.canhw_pull_pos >= ARRAY_SIZE(UsbCan.canhw_queue))
// No space - drop message
return;
if (UsbCan.assigned_id && (msg->id & ~1) == UsbCan.assigned_id)
// Id reserved for local
return;
uint32_t pos = pushp % ARRAY_SIZE(UsbCan.queue);
memcpy(&UsbCan.queue[pos], msg, sizeof(*msg));
UsbCan.push_pos = pushp + 1;
uint32_t pos = pushp % ARRAY_SIZE(UsbCan.canhw_queue);
memcpy(&UsbCan.canhw_queue[pos], msg, sizeof(*msg));
UsbCan.canhw_push_pos = pushp + 1;
usb_notify_bulk_out();
}

Expand All @@ -167,24 +165,43 @@ send_frame(struct canbus_msg *msg)

// Send any pending hw frames to host
static void
drain_hw_queue(void)
drain_canhw_queue(void)
{
uint32_t pull_pos = UsbCan.pull_pos;
uint32_t pull_pos = UsbCan.canhw_pull_pos;
for (;;) {
uint32_t push_pos = readl(&UsbCan.push_pos);
uint32_t push_pos = readl(&UsbCan.canhw_push_pos);
if (push_pos == pull_pos) {
// No more data to send
UsbCan.usb_send_busy = 0;
return;
}
uint32_t pos = pull_pos % ARRAY_SIZE(UsbCan.queue);
int ret = send_frame(&UsbCan.queue[pos]);
uint32_t pos = pull_pos % ARRAY_SIZE(UsbCan.canhw_queue);
int ret = send_frame(&UsbCan.canhw_queue[pos]);
if (ret < 0) {
// USB is busy - retry later
UsbCan.usb_send_busy = 1;
return;
}
UsbCan.pull_pos = pull_pos = pull_pos + 1;
UsbCan.canhw_pull_pos = pull_pos = pull_pos + 1;
}
}

// Fill local queue with any USB messages sent from host
static void
fill_usb_host_queue(void)
{
uint32_t pull_pos = UsbCan.host_pull_pos, push_pos = UsbCan.host_push_pos;
for (;;) {
if (push_pos - pull_pos >= ARRAY_SIZE(UsbCan.host_frames))
// No more space in queue
break;
uint32_t pushp = push_pos % ARRAY_SIZE(UsbCan.host_frames);
struct gs_host_frame *gs = &UsbCan.host_frames[pushp];
int ret = usb_read_bulk_out(gs, sizeof(*gs));
if (ret <= 0)
// No more messages ready
break;
UsbCan.host_push_pos = push_pos = push_pos + 1;
}
}

Expand All @@ -195,13 +212,19 @@ usbcan_task(void)
return;

// Send any pending hw frames to host
drain_hw_queue();
drain_canhw_queue();

// Fill local queue with any USB messages arriving from host
fill_usb_host_queue();

// Route messages received from host
uint32_t pull_pos = UsbCan.host_pull_pos, push_pos = UsbCan.host_push_pos;
uint32_t pullp = pull_pos % ARRAY_SIZE(UsbCan.host_frames);
struct gs_host_frame *gs = &UsbCan.host_frames[pullp];
for (;;) {
// See if previous host frame needs to be transmitted
uint_fast8_t host_status = UsbCan.host_status;
if (host_status & (HS_TX_HW | HS_TX_LOCAL)) {
struct gs_host_frame *gs = &UsbCan.host_frame;
struct canbus_msg msg;
msg.id = gs->can_id;
msg.dlc = gs->can_dlc;
Expand All @@ -221,30 +244,30 @@ usbcan_task(void)

// Send any previous echo frames
if (host_status) {
if (UsbCan.usb_send_busy)
if (UsbCan.notify_local || UsbCan.usb_send_busy)
// Don't send echo frame until other traffic is sent
return;
int ret = usb_send_bulk_in(&UsbCan.host_frame
, sizeof(UsbCan.host_frame));
break;
int ret = usb_send_bulk_in(gs, sizeof(*gs));
if (ret < 0)
return;
UsbCan.host_status = 0;
UsbCan.host_pull_pos = pull_pos = pull_pos + 1;
}

// Read next frame from host
int ret = usb_read_bulk_out(&UsbCan.host_frame
, USB_CDC_EP_BULK_OUT_SIZE);
if (ret <= 0)
// Process next frame from host
if (pull_pos == push_pos)
// No frame available - no more work to be done
break;
uint32_t id = UsbCan.host_frame.can_id;
gs = &UsbCan.host_frames[pull_pos % ARRAY_SIZE(UsbCan.host_frames)];
uint32_t id = gs->can_id;
UsbCan.host_status = HS_TX_ECHO | HS_TX_HW;
if (id == CANBUS_ID_ADMIN)
UsbCan.host_status = HS_TX_ECHO | HS_TX_HW | HS_TX_LOCAL;
else if (UsbCan.assigned_id && UsbCan.assigned_id == id)
UsbCan.host_status = HS_TX_ECHO | HS_TX_LOCAL;
}

// Wake up local message response handling (if usb is not busy)
if (UsbCan.notify_local && !UsbCan.usb_send_busy)
canserial_notify_tx();
}
Expand All @@ -258,6 +281,8 @@ canbus_send(struct canbus_msg *msg)
int ret = send_frame(msg);
if (ret < 0)
goto retry_later;
if (UsbCan.notify_local && UsbCan.host_status)
canbus_notify_tx();
UsbCan.notify_local = 0;
return msg->dlc;
retry_later:
Expand Down