diff options
Diffstat (limited to 'devices/uart_16550.c')
| -rw-r--r-- | devices/uart_16550.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/devices/uart_16550.c b/devices/uart_16550.c index 7cec968..22f33ad 100644 --- a/devices/uart_16550.c +++ b/devices/uart_16550.c @@ -1,6 +1,47 @@ #include "uart_16550.h" #include <sys/io.h> +enum uart_16550_offset { + Data = 0, // read from receive buffer / write to transmit buffer | BaudDiv_l + InterruptControl = 1, // interrupt enable | BaudDiv_h + FifoControl = 2, // interrupt ID and FIFO control + LineControl = 3, // most significant bit is the DLAB + ModemControl = 4, + LineStatus = 5, + ModemStatus = 6, + Scratch = 7, +}; +// Line Control +// | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | +// |dla| | parity | s | data | + +enum LineControl { + d5bit = 0x00, // 0000 0000 data bits + d6bit = 0x01, // 0000 0001 + d7bit = 0x02, // 0000 0010 + d8bit = 0x03, // 0000 0011 + // none = 0b00000000, // parity bits + odd = 0x08, // 0000 1000 + even = 0x18, // 0001 1000 + mark = 0x28, // 0010 1000 + space = 0x38, // 0011 1000 + // s1bit = 0b00000000, // stop bits + s2bit = 0x04, // 0000 0100 1.5 for 5bit data; 2 otherwise + dlab = 0x80 // 1000 0000 divisor latch access bit +}; + +// Line Status Register +enum LineStatus { + DR = (1 << 0), // data ready: see if there is data to read + OE = (1 << 1), // overrun error: see if there has been data lost + PE = (1 << 2), // parity error: see if there was error in transmission + FE = (1 << 3), // framing error: see if a stop bit was missing + BI = (1 << 4), // break indicator: see if there is a break in data input + THRE = (1 << 5), // transmitter holding register empty: see if transmission buffer is empty + TEMT = (1 << 6), // transmitter empty: see if transmitter is not doing anything + ERRO = (1 << 7), // impending error: see if there is an error with a word in the input buffer +}; + int uart_init(enum UART port) { |