[PATCH-for-8.2 v4 09/10] hw/char/pl011: Add transmit FIFO to PL011State

[Philippe Mathieu-Daudé]

In order to make the next commit easier to review,
introduce the transmit FIFO, but do not yet use it.

When migrating from new to old VM:
- if the fifo is empty, migration will still work because
   of the subsection.
- if the fifo is not empty, the subsection will be ignored,
  with the only consequence being that some characters will
  be dropped.

Uninline pl011_reset_tx_fifo().

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 include/hw/char/pl011.h |  2 ++
 hw/char/pl011.c         | 37 +++++++++++++++++++++++++++++++++++--
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/include/hw/char/pl011.h b/include/hw/char/pl011.h
index d853802132..20898f43a6 100644
--- a/include/hw/char/pl011.h
+++ b/include/hw/char/pl011.h
@@ -18,6 +18,7 @@
 #include "hw/sysbus.h"
 #include "chardev/char-fe.h"
 #include "qom/object.h"
+#include "qemu/fifo8.h"
 
 #define TYPE_PL011 "pl011"
 OBJECT_DECLARE_SIMPLE_TYPE(PL011State, PL011)
@@ -53,6 +54,7 @@ struct PL011State {
     Clock *clk;
     bool migrate_clk;
     const unsigned char *id;
+    Fifo8 xmit_fifo;
 };
 
 DeviceState *pl011_create(hwaddr addr, qemu_irq irq, Chardev *chr);
diff --git a/hw/char/pl011.c b/hw/char/pl011.c
index 727decd428..f474f56780 100644
--- a/hw/char/pl011.c
+++ b/hw/char/pl011.c
@@ -147,11 +147,13 @@ static inline void pl011_reset_rx_fifo(PL011State *s)
     s->flags |= PL011_FLAG_RXFE;
 }
 
-static inline void pl011_reset_tx_fifo(PL011State *s)
+static void pl011_reset_tx_fifo(PL011State *s)
 {
     /* Reset FIFO flags */
     s->flags &= ~PL011_FLAG_TXFF;
     s->flags |= PL011_FLAG_TXFE;
+
+    fifo8_reset(&s->xmit_fifo);
 }
 
 static void pl011_write_txdata(PL011State *s, uint8_t data)
@@ -436,6 +438,24 @@ static const VMStateDescription vmstate_pl011_clock = {
     }
 };
 
+static bool pl011_xmit_fifo_state_needed(void *opaque)
+{
+    PL011State* s = opaque;
+
+    return !fifo8_is_empty(&s->xmit_fifo);
+}
+
+static const VMStateDescription vmstate_pl011_xmit_fifo = {
+    .name = "pl011/xmit_fifo",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = pl011_xmit_fifo_state_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_FIFO8(xmit_fifo, PL011State),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static int pl011_post_load(void *opaque, int version_id)
 {
     PL011State* s = opaque;
@@ -487,7 +507,11 @@ static const VMStateDescription vmstate_pl011 = {
     .subsections = (const VMStateDescription * []) {
         &vmstate_pl011_clock,
         NULL
-    }
+    },
+    .subsections = (const VMStateDescription * []) {
+        &vmstate_pl011_xmit_fifo,
+        NULL
+    },
 };
 
 static Property pl011_properties[] = {
@@ -502,6 +526,7 @@ static void pl011_init(Object *obj)
     PL011State *s = PL011(obj);
     int i;
 
+    fifo8_create(&s->xmit_fifo, PL011_FIFO_DEPTH);
     memory_region_init_io(&s->iomem, OBJECT(s), &pl011_ops, s, "pl011", 
0x1000);
     sysbus_init_mmio(sbd, &s->iomem);
     for (i = 0; i < ARRAY_SIZE(s->irq); i++) {
@@ -514,6 +539,13 @@ static void pl011_init(Object *obj)
     s->id = pl011_id_arm;
 }
 
+static void pl011_finalize(Object *obj)
+{
+    PL011State *s = PL011(obj);
+
+    fifo8_destroy(&s->xmit_fifo);
+}
+
 static void pl011_realize(DeviceState *dev, Error **errp)
 {
     PL011State *s = PL011(dev);
@@ -557,6 +589,7 @@ static const TypeInfo pl011_arm_info = {
     .parent        = TYPE_SYS_BUS_DEVICE,
     .instance_size = sizeof(PL011State),
     .instance_init = pl011_init,
+    .instance_finalize = pl011_finalize,
     .class_init    = pl011_class_init,
 };
 
-- 
2.41.0