drivers/tty/serial/jsm/jsm_neo.c

Source file repositories/reference/linux-study-clean/drivers/tty/serial/jsm/jsm_neo.c

File Facts

System
Linux kernel
Corpus path
drivers/tty/serial/jsm/jsm_neo.c
Extension
.c
Size
34852 bytes
Lines
1336
Domain
Driver Families
Bucket
drivers/tty
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (!(linestatus & UART_LSR_DR)) {
			ch->ch_cached_lsr = linestatus;
			break;
		}

		/* No need to store this bit */
		linestatus &= ~UART_LSR_DR;

		/*
		 * Since we are grabbing the linestatus register, which
		 * will reset some bits after our read, we need to ensure
		 * we don't miss our TX FIFO emptys.
		 */
		if (linestatus & (UART_LSR_THRE | UART_17158_TX_AND_FIFO_CLR)) {
			linestatus &= ~(UART_LSR_THRE | UART_17158_TX_AND_FIFO_CLR);
			ch->ch_flags |= (CH_TX_FIFO_EMPTY | CH_TX_FIFO_LWM);
		}

		/*
		 * Discard character if we are ignoring the error mask.
		 */
		if (linestatus & error_mask) {
			u8 discard;
			linestatus = 0;
			memcpy_fromio(&discard, &ch->ch_neo_uart->txrxburst, 1);
			continue;
		}

		/*
		 * If our queue is full, we have no choice but to drop some data.
		 * The assumption is that HWFLOW or SWFLOW should have stopped
		 * things way way before we got to this point.
		 *
		 * I decided that I wanted to ditch the oldest data first,
		 * I hope thats okay with everyone? Yes? Good.
		 */
		while (qleft < 1) {
			jsm_dbg(READ, &ch->ch_bd->pci_dev,
				"Queue full, dropping DATA:%x LSR:%x\n",
				ch->ch_rqueue[tail], ch->ch_equeue[tail]);

			ch->ch_r_tail = tail = (tail + 1) & RQUEUEMASK;
			ch->ch_err_overrun++;
			qleft++;
		}

		memcpy_fromio(ch->ch_rqueue + head, &ch->ch_neo_uart->txrxburst, 1);
		ch->ch_equeue[head] = (u8) linestatus;

		jsm_dbg(READ, &ch->ch_bd->pci_dev, "DATA/LSR pair: %x %x\n",
			ch->ch_rqueue[head], ch->ch_equeue[head]);

		/* Ditch any remaining linestatus value. */
		linestatus = 0;

		/* Add to and flip head if needed */
		head = (head + 1) & RQUEUEMASK;

		qleft--;
		ch->ch_rxcount++;
	}

	/*
	 * Write new final heads to channel structure.
	 */
	ch->ch_r_head = head & RQUEUEMASK;
	ch->ch_e_head = head & EQUEUEMASK;
	jsm_input(ch);
}

static void neo_copy_data_from_queue_to_uart(struct jsm_channel *ch)
{
	struct tty_port *tport;
	unsigned char *tail;
	unsigned char c;
	int n;
	int s;
	int qlen;
	u32 len_written = 0;

	if (!ch)
		return;

	tport = &ch->uart_port.state->port;

	/* No data to write to the UART */
	if (kfifo_is_empty(&tport->xmit_fifo))
		return;

	/* If port is "stopped", don't send any data to the UART */

Annotation

Implementation Notes