From f4eef224a09f4ea4344211dabfb875dd865df479 Mon Sep 17 00:00:00 2001 From: Angelo Dureghello Date: Sun, 4 Oct 2020 18:11:44 +0200 Subject: serial: fsl_lpuart: add sysrq support when using dma Add handling of magic sysrq keys when using dma/edma. Tested by sending BREAK followed by a sysrq command inside a 5 secs time window, by: echo 1 > /proc/sys/kernel/sysrq BREAK + h, t, e, b, c Tested also sending a command after 5 secs after BREAK, that's properly ignored. Signed-off-by: Angelo Dureghello Link: https://lore.kernel.org/r/20201004161144.1307174-1-angelo.dureghello@timesys.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/fsl_lpuart.c | 57 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) (limited to 'drivers/tty/serial/fsl_lpuart.c') diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 590c901a1fc5..ff4b88c637d0 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -976,6 +976,15 @@ static irqreturn_t lpuart_int(int irq, void *dev_id) sts = readb(sport->port.membase + UARTSR1); + /* SysRq, using dma, check for linebreak by framing err. */ + if (sts & UARTSR1_FE && sport->lpuart_dma_rx_use) { + readb(sport->port.membase + UARTDR); + uart_handle_break(&sport->port); + /* linebreak produces some garbage, removing it */ + writeb(UARTCFIFO_RXFLUSH, sport->port.membase + UARTCFIFO); + return IRQ_HANDLED; + } + if (sts & UARTSR1_RDRF && !sport->lpuart_dma_rx_use) lpuart_rxint(sport); @@ -1004,6 +1013,37 @@ static irqreturn_t lpuart32_int(int irq, void *dev_id) return IRQ_HANDLED; } + +static inline void lpuart_handle_sysrq_chars(struct uart_port *port, + unsigned char *p, int count) +{ + while (count--) { + if (*p && uart_handle_sysrq_char(port, *p)) + return; + p++; + } +} + +static void lpuart_handle_sysrq(struct lpuart_port *sport) +{ + struct circ_buf *ring = &sport->rx_ring; + int count; + + if (ring->head < ring->tail) { + count = sport->rx_sgl.length - ring->tail; + lpuart_handle_sysrq_chars(&sport->port, + ring->buf + ring->tail, count); + ring->tail = 0; + } + + if (ring->head > ring->tail) { + count = ring->head - ring->tail; + lpuart_handle_sysrq_chars(&sport->port, + ring->buf + ring->tail, count); + ring->tail = ring->head; + } +} + static void lpuart_copy_rx_to_tty(struct lpuart_port *sport) { struct tty_port *port = &sport->port.state->port; @@ -1090,6 +1130,15 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport) */ ring->head = sport->rx_sgl.length - state.residue; BUG_ON(ring->head > sport->rx_sgl.length); + + /* + * Silent handling of keys pressed in the sysrq timeframe + */ + if (sport->port.sysrq) { + lpuart_handle_sysrq(sport); + goto exit; + } + /* * At this point ring->head may point to the first byte right after the * last byte of the dma buffer: @@ -1121,6 +1170,7 @@ static void lpuart_copy_rx_to_tty(struct lpuart_port *sport) sport->port.icount.rx += count; } +exit: dma_sync_sg_for_device(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE); @@ -1557,6 +1607,7 @@ err: static void lpuart_rx_dma_startup(struct lpuart_port *sport) { int ret; + unsigned char cr3; if (!sport->dma_rx_chan) goto err; @@ -1573,6 +1624,12 @@ static void lpuart_rx_dma_startup(struct lpuart_port *sport) sport->lpuart_dma_rx_use = true; rx_dma_timer_init(sport); + if (sport->port.has_sysrq) { + cr3 = readb(sport->port.membase + UARTCR3); + cr3 |= UARTCR3_FEIE; + writeb(cr3, sport->port.membase + UARTCR3); + } + return; err: -- cgit v1.2.3