1 // uart_virt.cc
2 // QEMU `virt` generic virtual platform
3 
4 
5 #include <hw.h>
6 #include <uart.h>
7 #include <pl011.h>
8 
9 
10 namespace Board {
11 namespace Uart {
12 
13 
14 namespace {
15 
16 constexpr uintptr_t UART_BASE = 0x9000000;
17 
18 } // anonymous namespace
19 
20 
21 void initialize()
22 {
23     Pl011::ControlRegister ControlRegister;
24     ControlRegister.m_u.m_Bits.m_UartEnable = 1;
25     ControlRegister.m_u.m_Bits.m_TransmitEnable = 1;
26     ControlRegister.m_u.m_Bits.m_ReceiveEnable = 1;
27     Hw::write32(UART_BASE + Pl011::CONTROL_REGISTER, ControlRegister.m_u.m_nValue);
28 }
29 
30 
31 void send(uint8_t nValue)
32 {
33     // spin while fifo is full
34     for (; ; )
35     {
36         Pl011::FlagRegister FlagRegister{Hw::read32(UART_BASE + Pl011::FLAG_REGISTER)};
37         if (!FlagRegister.m_u.m_Bits.m_TransmitFifoFull)
38             break;
39     }
40     Hw::write32(UART_BASE + Pl011::DATA_REGISTER, nValue);
41 }
42 
43 
44 uint8_t recv()
45 {
46     for (; ; )
47     {
48         Pl011::FlagRegister FlagRegister{Hw::read32(UART_BASE + Pl011::FLAG_REGISTER)};
49         if (!FlagRegister.m_u.m_Bits.m_ReceiveFifoEmpty)
50             break;
51     }
52     return Hw::read32(UART_BASE + Pl011::DATA_REGISTER) & 0xff;
53 }
54 
55 
56 } // namespace Uart
57 } // namespace Board