BL808_UART_FIFO_RDATA_OFFSET (0x3000208c) returns the Input Char

lupyuen · Jan 20, 2024 · 63cba62 · 63cba62
1 parent 3d2430d
commit 63cba62
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Showing 2 changed files with 33 additions and 4 deletions.
diff --git a/riscv_cpu.c b/riscv_cpu.c
@@ -382,10 +382,15 @@ int target_read_slow(RISCVCPUState *s, mem_uint_t *pval,
         if (!pr) {
             //// Begin Test: Intercept Memory-Mapped I/O
             switch(paddr) {
-            case 0x30002084:     // uart_fifo_config_1: Is UART Ready?
-                ret = 32         // UART TX is always ready, default TX FIFO Available is 32
-                    | (1 << 8);  // UART RX FIFO Available is always 1
+            case 0x30002084: { // uart_fifo_config_1: Is UART Ready?
+                char read_input(void);
+                uint8_t rx_avail = (read_input() == 0)  // Check input buffer
+                    ? 0   // No input available
+                    : 1;  // One char available
+                ret = 32  // UART TX is always ready, default TX FIFO Available is 32
+                    | (rx_avail << 8);  // UART RX FIFO Available depends on input buffer
                 break;
+            }
 
             // Console Input: BL808_UART_INT_STS (0x30002020) must return UART_INT_STS_URX_END_INT (1 << 1)
             case 0x30002020:
@@ -397,6 +402,16 @@ int target_read_slow(RISCVCPUState *s, mem_uint_t *pval,
                 puts("read BL808_UART_INT_MASK");
                 ret = 0; break;
 
+            // Console Input: BL808_UART_FIFO_RDATA_OFFSET (0x3000208c) returns the Input Char
+            case 0x3000208c: {
+                char read_input(void);
+                ret = read_input();
+
+                // Clear the Input Buffer
+                void set_input(char ch);
+                set_input(0);
+                break;
+            }
             default:  // Unknown Memory-Mapped I/O
 #ifdef DUMP_INVALID_MEM_ACCESS
                 printf("target_read_slow: invalid physical address 0x");

diff --git a/virtio.c b/virtio.c
@@ -158,7 +158,9 @@ static void virtio_mmio_write(void *opaque, uint32_t offset,
 static uint32_t virtio_pci_read(void *opaque, uint32_t offset, int size_log2);
 static void virtio_pci_write(void *opaque, uint32_t offset,
                              uint32_t val, int size_log2);
+
 void virtio_ack_irq(VIRTIODevice *device0);
+void set_input(char ch);
 
 static void virtio_reset(VIRTIODevice *s)
 {
@@ -1334,8 +1336,9 @@ int virtio_console_get_write_len(VIRTIODevice *s)
 int virtio_console_write_data(VIRTIODevice *s, const uint8_t *buf, int buf_len)
 {
     //// To handle a keypress, we trigger the UART3 Interrupt.
-    //// TODO: Pass the keypress to VM Guest
+    //// Pass the keypress to VM Guest
     printf("[%c]\n", buf[0]); ////
+    set_input(buf[0]);
     s->int_status |= 1;
     set_irq(s->irq, 1);
 
@@ -2690,4 +2693,15 @@ void virtio_ack_irq(VIRTIODevice *device0) {
         set_irq(device->irq, 0);
     // }
 }
+
+//// Remember and return the Input Char
+static char input_char = 0;
+
+void set_input(char ch) {
+    input_char = ch;    
+}
+
+char read_input(void) {
+    return input_char;
+}
 //// End Test