From 86baecc3e43510c3bef03a0d7e947221823864d3 Mon Sep 17 00:00:00 2001 From: Peter Crosthwaite Date: Mon, 6 Jan 2014 10:16:40 +0000 Subject: [PATCH] char/cadence_uart: Use the TX fifo for transmission Populate the TxFIFO with the Tx data before sending. Prepares support for proper Tx flow control implementation. Signed-off-by: Peter Crosthwaite Message-id: bdf7f8af2ef02839bea18665701bc2612f7baa6f.1388626249.git.peter.crosthwaite@xilinx.com Signed-off-by: Peter Maydell --- hw/char/cadence_uart.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/hw/char/cadence_uart.c b/hw/char/cadence_uart.c index 3bcaf2905d..be32126bdc 100644 --- a/hw/char/cadence_uart.c +++ b/hw/char/cadence_uart.c @@ -292,7 +292,22 @@ static void uart_write_tx_fifo(UartState *s, const uint8_t *buf, int size) return; } - qemu_chr_fe_write_all(s->chr, buf, size); + if (size > TX_FIFO_SIZE - s->tx_count) { + size = TX_FIFO_SIZE - s->tx_count; + /* + * This can only be a guest error via a bad tx fifo register push, + * as can_receive() should stop remote loop and echo modes ever getting + * us to here. + */ + qemu_log_mask(LOG_GUEST_ERROR, "cadence_uart: TxFIFO overflow"); + s->r[R_CISR] |= UART_INTR_ROVR; + } + + memcpy(s->tx_fifo + s->tx_count, buf, size); + s->tx_count += size; + + qemu_chr_fe_write_all(s->chr, s->tx_fifo, s->tx_count); + s->tx_count = 0; } static void uart_receive(void *opaque, const uint8_t *buf, int size)