Commit ce8f0905 authored by Rob Herring's avatar Rob Herring Committed by Peter Maydell
Browse files

pl011: fix UARTRSR accesses corrupting the UARTCR value 



Offset 4 is UARTRSR/UARTECR, not the UARTCR. The UARTCR would be
corrupted if the UARTRSR is ever written. Fix by implementing a correct
model of the UARTRSR/UARTECR register. Reads of this register simply
reflect the error bits in data register. Only breaks can be triggered in
QEMU. With the pl011_can_receive function, we effectively have flow
control between the host and the model. Framing and parity errors simply
don't make sense in the model and will never occur.

Signed-off-by: default avatarRob Herring <rob.herring@linaro.org>
Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Message-id: 1395166721-15716-3-git-send-email-robherring2@gmail.com
Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
parent 22709e90

hw/char/pl011.c

+10 −7
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ typedef struct PL011State { 
    uint32_t readbuff;

    uint32_t flags;

    uint32_t lcr;

    uint32_t rsr;

    uint32_t cr;

    uint32_t dmacr;

    uint32_t int_enabled;
@@ -81,13 +82,14 @@ static uint64_t pl011_read(void *opaque, hwaddr offset, 
        }

        if (s->read_count == s->read_trigger - 1)

            s->int_level &= ~ PL011_INT_RX;

        s->rsr = c >> 8;

        pl011_update(s);

        if (s->chr) {

            qemu_chr_accept_input(s->chr);

        }

        return c;

    case 1: /* UARTCR */

        return 0;

    case 1: /* UARTRSR */

        return s->rsr;

    case 6: /* UARTFR */

        return s->flags;

    case 8: /* UARTILPR */
@@ -146,8 +148,8 @@ static void pl011_write(void *opaque, hwaddr offset, 
        s->int_level |= PL011_INT_TX;

        pl011_update(s);

        break;

    case 1: /* UARTCR */

        s->cr = value;

    case 1: /* UARTRSR/UARTECR */

        s->rsr = 0;

        break;

    case 6: /* UARTFR */

        /* Writes to Flag register are ignored.  */
@@ -247,13 +249,14 @@ static const MemoryRegionOps pl011_ops = { 


static const VMStateDescription vmstate_pl011 = {

    .name = "pl011",

    .version_id = 1,

    .minimum_version_id = 1,

    .minimum_version_id_old = 1,

    .version_id = 2,

    .minimum_version_id = 2,

    .minimum_version_id_old = 2,

    .fields      = (VMStateField[]) {

        VMSTATE_UINT32(readbuff, PL011State),

        VMSTATE_UINT32(flags, PL011State),

        VMSTATE_UINT32(lcr, PL011State),

        VMSTATE_UINT32(rsr, PL011State),

        VMSTATE_UINT32(cr, PL011State),

        VMSTATE_UINT32(dmacr, PL011State),

        VMSTATE_UINT32(int_enabled, PL011State),