[PATCH 1/1] stm32f2xx_usart: implement TX interrupts

[Hans-Erik Floryd]

Generate interrupt if either of the TXE, TC or RXNE bits are active
and the corresponding interrupt enable bit is set.

Signed-off-by: Hans-Erik Floryd <hans-erik.flo...@rt-labs.com>
---
 hw/char/stm32f2xx_usart.c         | 29 +++++++++++++++++------------
 include/hw/char/stm32f2xx_usart.h | 10 ++++++----
 2 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/hw/char/stm32f2xx_usart.c b/hw/char/stm32f2xx_usart.c
index fde67f4f03..2947c3a260 100644
--- a/hw/char/stm32f2xx_usart.c
+++ b/hw/char/stm32f2xx_usart.c
@@ -53,6 +53,16 @@ static int stm32f2xx_usart_can_receive(void *opaque)
     return 0;
 }
 
+static void stm32f2xx_update(STM32F2XXUsartState *s)
+{
+    uint32_t mask = s->usart_sr & s->usart_cr1;
+    if (mask & (USART_SR_TXE | USART_SR_TC | USART_SR_RXNE)) {
+        qemu_set_irq(s->irq, 1);
+    } else {
+        qemu_set_irq(s->irq, 0);
+    }
+}
+
 static void stm32f2xx_usart_receive(void *opaque, const uint8_t *buf, int size)
 {
     STM32F2XXUsartState *s = opaque;
@@ -66,9 +76,7 @@ static void stm32f2xx_usart_receive(void *opaque, const 
uint8_t *buf, int size)
     s->usart_dr = *buf;
     s->usart_sr |= USART_SR_RXNE;
 
-    if (s->usart_cr1 & USART_CR1_RXNEIE) {
-        qemu_set_irq(s->irq, 1);
-    }
+    stm32f2xx_update(s);
 
     DB_PRINT("Receiving: %c\n", s->usart_dr);
 }
@@ -85,7 +93,7 @@ static void stm32f2xx_usart_reset(DeviceState *dev)
     s->usart_cr3 = 0x00000000;
     s->usart_gtpr = 0x00000000;
 
-    qemu_set_irq(s->irq, 0);
+    stm32f2xx_update(s);
 }
 
 static uint64_t stm32f2xx_usart_read(void *opaque, hwaddr addr,
@@ -100,13 +108,14 @@ static uint64_t stm32f2xx_usart_read(void *opaque, hwaddr 
addr,
     case USART_SR:
         retvalue = s->usart_sr;
         qemu_chr_fe_accept_input(&s->chr);
+        stm32f2xx_update(s);
         return retvalue;
     case USART_DR:
         DB_PRINT("Value: 0x%" PRIx32 ", %c\n", s->usart_dr, (char) 
s->usart_dr);
         retvalue = s->usart_dr & 0x3FF;
         s->usart_sr &= ~USART_SR_RXNE;
         qemu_chr_fe_accept_input(&s->chr);
-        qemu_set_irq(s->irq, 0);
+        stm32f2xx_update(s);
         return retvalue;
     case USART_BRR:
         return s->usart_brr;
@@ -145,9 +154,7 @@ static void stm32f2xx_usart_write(void *opaque, hwaddr addr,
         } else {
             s->usart_sr &= value;
         }
-        if (!(s->usart_sr & USART_SR_RXNE)) {
-            qemu_set_irq(s->irq, 0);
-        }
+        stm32f2xx_update(s);
         return;
     case USART_DR:
         if (value < 0xF000) {
@@ -161,6 +168,7 @@ static void stm32f2xx_usart_write(void *opaque, hwaddr addr,
                clear TC by writing 0 to the SR register, so set it again
                on each write. */
             s->usart_sr |= USART_SR_TC;
+            stm32f2xx_update(s);
         }
         return;
     case USART_BRR:
@@ -168,10 +176,7 @@ static void stm32f2xx_usart_write(void *opaque, hwaddr 
addr,
         return;
     case USART_CR1:
         s->usart_cr1 = value;
-            if (s->usart_cr1 & USART_CR1_RXNEIE &&
-                s->usart_sr & USART_SR_RXNE) {
-                qemu_set_irq(s->irq, 1);
-            }
+        stm32f2xx_update(s);
         return;
     case USART_CR2:
         s->usart_cr2 = value;
diff --git a/include/hw/char/stm32f2xx_usart.h 
b/include/hw/char/stm32f2xx_usart.h
index 65bcc85470..fdfa7424a7 100644
--- a/include/hw/char/stm32f2xx_usart.h
+++ b/include/hw/char/stm32f2xx_usart.h
@@ -48,10 +48,12 @@
 #define USART_SR_TC   (1 << 6)
 #define USART_SR_RXNE (1 << 5)
 
-#define USART_CR1_UE  (1 << 13)
-#define USART_CR1_RXNEIE  (1 << 5)
-#define USART_CR1_TE  (1 << 3)
-#define USART_CR1_RE  (1 << 2)
+#define USART_CR1_UE     (1 << 13)
+#define USART_CR1_TXEIE  (1 << 7)
+#define USART_CR1_TCEIE  (1 << 6)
+#define USART_CR1_RXNEIE (1 << 5)
+#define USART_CR1_TE     (1 << 3)
+#define USART_CR1_RE     (1 << 2)
 
 #define TYPE_STM32F2XX_USART "stm32f2xx-usart"
 OBJECT_DECLARE_SIMPLE_TYPE(STM32F2XXUsartState, STM32F2XX_USART)
-- 
2.42.0