From 9d88935cb19f8f8e7291026efe23862316ff2510 Mon Sep 17 00:00:00 2001 From: Evgeny Iakovlev Date: Mon, 23 Jan 2023 17:23:00 +0100 Subject: hw/char/pl011: refactor FIFO depth handling code MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit PL011 can be in either of 2 modes depending guest config: FIFO and single register. The last mode could be viewed as a 1-element-deep FIFO. Current code open-codes a bunch of depth-dependent logic. Refactor FIFO depth handling code to isolate calculating current FIFO depth. One functional (albeit guest-invisible) side-effect of this change is that previously we would always increment s->read_pos in UARTDR read handler even if FIFO was disabled, now we are limiting read_pos to not exceed FIFO depth (read_pos itself is reset to 0 if user disables FIFO). Signed-off-by: Evgeny Iakovlev Reviewed-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daudé Message-id: 20230123162304.26254-2-eiakovlev@linux.microsoft.com Signed-off-by: Peter Maydell --- hw/char/pl011.c | 30 ++++++++++++++++++------------ include/hw/char/pl011.h | 5 ++++- 2 files changed, 22 insertions(+), 13 deletions(-) diff --git a/hw/char/pl011.c b/hw/char/pl011.c index c076813..3fa3b75 100644 --- a/hw/char/pl011.c +++ b/hw/char/pl011.c @@ -81,6 +81,17 @@ static void pl011_update(PL011State *s) } } +static bool pl011_is_fifo_enabled(PL011State *s) +{ + return (s->lcr & 0x10) != 0; +} + +static inline unsigned pl011_get_fifo_depth(PL011State *s) +{ + /* Note: FIFO depth is expected to be power-of-2 */ + return pl011_is_fifo_enabled(s) ? PL011_FIFO_DEPTH : 1; +} + static uint64_t pl011_read(void *opaque, hwaddr offset, unsigned size) { @@ -94,8 +105,7 @@ static uint64_t pl011_read(void *opaque, hwaddr offset, c = s->read_fifo[s->read_pos]; if (s->read_count > 0) { s->read_count--; - if (++s->read_pos == 16) - s->read_pos = 0; + s->read_pos = (s->read_pos + 1) & (pl011_get_fifo_depth(s) - 1); } if (s->read_count == 0) { s->flags |= PL011_FLAG_RXFE; @@ -273,11 +283,7 @@ static int pl011_can_receive(void *opaque) PL011State *s = (PL011State *)opaque; int r; - if (s->lcr & 0x10) { - r = s->read_count < 16; - } else { - r = s->read_count < 1; - } + r = s->read_count < pl011_get_fifo_depth(s); trace_pl011_can_receive(s->lcr, s->read_count, r); return r; } @@ -286,15 +292,15 @@ static void pl011_put_fifo(void *opaque, uint32_t value) { PL011State *s = (PL011State *)opaque; int slot; + unsigned pipe_depth; - slot = s->read_pos + s->read_count; - if (slot >= 16) - slot -= 16; + pipe_depth = pl011_get_fifo_depth(s); + slot = (s->read_pos + s->read_count) & (pipe_depth - 1); s->read_fifo[slot] = value; s->read_count++; s->flags &= ~PL011_FLAG_RXFE; trace_pl011_put_fifo(value, s->read_count); - if (!(s->lcr & 0x10) || s->read_count == 16) { + if (s->read_count == pipe_depth) { trace_pl011_put_fifo_full(); s->flags |= PL011_FLAG_RXFF; } @@ -359,7 +365,7 @@ static const VMStateDescription vmstate_pl011 = { VMSTATE_UINT32(dmacr, PL011State), VMSTATE_UINT32(int_enabled, PL011State), VMSTATE_UINT32(int_level, PL011State), - VMSTATE_UINT32_ARRAY(read_fifo, PL011State, 16), + VMSTATE_UINT32_ARRAY(read_fifo, PL011State, PL011_FIFO_DEPTH), VMSTATE_UINT32(ilpr, PL011State), VMSTATE_UINT32(ibrd, PL011State), VMSTATE_UINT32(fbrd, PL011State), diff --git a/include/hw/char/pl011.h b/include/hw/char/pl011.h index dc2c90e..926322e 100644 --- a/include/hw/char/pl011.h +++ b/include/hw/char/pl011.h @@ -27,6 +27,9 @@ OBJECT_DECLARE_SIMPLE_TYPE(PL011State, PL011) /* This shares the same struct (and cast macro) as the base pl011 device */ #define TYPE_PL011_LUMINARY "pl011_luminary" +/* Depth of UART FIFO in bytes, when FIFO mode is enabled (else depth == 1) */ +#define PL011_FIFO_DEPTH 16 + struct PL011State { SysBusDevice parent_obj; @@ -39,7 +42,7 @@ struct PL011State { uint32_t dmacr; uint32_t int_enabled; uint32_t int_level; - uint32_t read_fifo[16]; + uint32_t read_fifo[PL011_FIFO_DEPTH]; uint32_t ilpr; uint32_t ibrd; uint32_t fbrd; -- cgit v1.1