On 28/01/2012 13:20, Blue Swirl wrote:
> On Thu, Jan 26, 2012 at 17:03, Fabien Chouteau <chout...@adacore.com> wrote:
>> This patch implements the RX channel of GRLIB UART with a FIFO to
>> improve data rate.
>>
>> Signed-off-by: Fabien Chouteau <chout...@adacore.com>
>> ---
>> hw/grlib_apbuart.c | 106
>> +++++++++++++++++++++++++++++++++++++++++++--------
>> trace-events | 1 +
>> 2 files changed, 90 insertions(+), 17 deletions(-)
>>
>> diff --git a/hw/grlib_apbuart.c b/hw/grlib_apbuart.c
>> index f8a64e1..51406c6 100644
>> --- a/hw/grlib_apbuart.c
>> +++ b/hw/grlib_apbuart.c
>> @@ -24,7 +24,6 @@
>>
>> #include "sysbus.h"
>> #include "qemu-char.h"
>> -#include "ptimer.h"
>>
>> #include "trace.h"
>>
>> @@ -66,6 +65,8 @@
>> #define SCALER_OFFSET 0x0C /* not supported */
>> #define FIFO_DEBUG_OFFSET 0x10 /* not supported */
>>
>> +#define FIFO_LENGTH 1024
>> +
>> typedef struct UART {
>> SysBusDevice busdev;
>> MemoryRegion iomem;
>> @@ -77,21 +78,67 @@ typedef struct UART {
>> uint32_t receive;
>> uint32_t status;
>> uint32_t control;
>> +
>> + /* FIFO */
>> + char buffer[FIFO_LENGTH];
>> + int len;
>> + int current;
>> } UART;
>>
>> +static int uart_data_to_read(UART *uart)
>> +{
>> + return uart->current < uart->len;
>> +}
>> +
>> +static char uart_pop(UART *uart)
>> +{
>> + char ret;
>> +
>> + if (uart->len == 0) {
>> + uart->status &= ~UART_DATA_READY;
>> + return 0;
>> + }
>> +
>> + ret = uart->buffer[uart->current++];
>> +
>> + if (uart->current >= uart->len) {
>> + /* Flush */
>> + uart->len = 0;
>> + uart->current = 0;
>> + }
>> +
>> + if (!uart_data_to_read(uart)) {
>> + uart->status &= ~UART_DATA_READY;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static void uart_add_to_fifo(UART *uart,
>> + const uint8_t *buffer,
>> + int length)
>> +{
>> + if (uart->len + length > FIFO_LENGTH) {
>> + abort();
>
> A guest could trigger this abort(), which is not OK. I think you can
> just return.
>
This will abort if Qemu sends more bytes than the number requested in
grlib_apbuart_can_receive, so this would be a failure from Qemu not the
guest.
Regards,
--
Fabien Chouteau
