From 85b7864a3d619e9d2fa839a784c0800773621f3b Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Wed, 6 Mar 2019 10:00:46 +0100 Subject: debug_ll: Add ns16550 early debugging functions Signed-off-by: Sascha Hauer --- include/debug_ll/ns16550.h | 56 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 include/debug_ll/ns16550.h diff --git a/include/debug_ll/ns16550.h b/include/debug_ll/ns16550.h new file mode 100644 index 0000000000..7e4dbeb453 --- /dev/null +++ b/include/debug_ll/ns16550.h @@ -0,0 +1,56 @@ +#ifndef __DEBUG_LL_NS16550_H +#define __DEBUG_LL_NS16550_H + +/* + * Early debugging functions for the NS16550 + * This file needs register access functions declared as: + * + * uint8_t debug_ll_read_reg(int reg); + * void debug_ll_write_reg(int reg, uint8_t val); + */ +#define NS16550_THR 0x0 +#define NS16550_RBR 0x0 +#define NS16550_DLL 0x0 +#define NS16550_IER 0x1 +#define NS16550_DLM 0x1 +#define NS16550_FCR 0x2 +#define NS16550_LCR 0x3 +#define NS16550_MCR 0x4 +#define NS16550_LSR 0x5 + +#define NS16550_LCR_VAL 0x3 /* 8 data, 1 stop, no parity */ +#define NS16550_MCR_VAL 0x3 /* RTS/DTR */ +#define NS16550_FCR_VAL 0x7 /* Clear & enable FIFOs */ + +#define NS16550_LSR_DR 0x01 /* UART received data present */ +#define NS16550_LSR_THRE 0x20 /* Xmit holding register empty */ + +#define NS16550_LCR_BKSE 0x80 /* Bank select enable */ + +static inline void PUTC_LL(char ch) +{ + while (!(debug_ll_read_reg(NS16550_LSR) & NS16550_LSR_THRE)) + ; + + debug_ll_write_reg(NS16550_THR, ch); +} + +static inline uint16_t debug_ll_ns16550_calc_divisor(unsigned long clk) +{ + return clk / (115200 * 16); +} + +static inline void debug_ll_ns16550_init(uint16_t divisor) +{ + debug_ll_write_reg(NS16550_LCR, 0x0); /* select ier reg */ + debug_ll_write_reg(0x00, NS16550_IER); + + debug_ll_write_reg(NS16550_LCR, NS16550_LCR_BKSE); + debug_ll_write_reg(NS16550_DLL, divisor & 0xff); + debug_ll_write_reg(NS16550_DLM, (divisor >> 8) & 0xff); + debug_ll_write_reg(NS16550_LCR, NS16550_LCR_VAL); + debug_ll_write_reg(NS16550_MCR, NS16550_MCR_VAL); + debug_ll_write_reg(NS16550_FCR, NS16550_FCR_VAL); +} + +#endif -- cgit v1.2.3