1// SPDX-License-Identifier: GPL-2.0
2/*
3 * 16550 serial console support.
4 *
5 * Original copied from <file:arch/ppc/boot/common/ns16550.c>
6 * (which had no copyright)
7 * Modifications: 2006 (c) MontaVista Software, Inc.
8 *
9 * Modified by: Mark A. Greer <mgreer@mvista.com>
10 */
11#include <stdarg.h>
12#include <stddef.h>
13#include "types.h"
14#include "string.h"
15#include "stdio.h"
16#include "io.h"
17#include "ops.h"
18#include "of.h"
19
20#define UART_DLL 0 /* Out: Divisor Latch Low */
21#define UART_DLM 1 /* Out: Divisor Latch High */
22#define UART_FCR 2 /* Out: FIFO Control Register */
23#define UART_LCR 3 /* Out: Line Control Register */
24#define UART_MCR 4 /* Out: Modem Control Register */
25#define UART_LSR 5 /* In: Line Status Register */
26#define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */
27#define UART_LSR_DR 0x01 /* Receiver data ready */
28#define UART_MSR 6 /* In: Modem Status Register */
29#define UART_SCR 7 /* I/O: Scratch Register */
30
31static unsigned char *reg_base;
32static u32 reg_shift;
33
34static int ns16550_open(void)
35{
36 out_8(addr: reg_base + (UART_FCR << reg_shift), val: 0x06);
37 return 0;
38}
39
40static void ns16550_putc(unsigned char c)
41{
42 while ((in_8(addr: reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
43 out_8(addr: reg_base, val: c);
44}
45
46static unsigned char ns16550_getc(void)
47{
48 while ((in_8(addr: reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
49 return in_8(addr: reg_base);
50}
51
52static u8 ns16550_tstc(void)
53{
54 return ((in_8(addr: reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
55}
56
57int ns16550_console_init(void *devp, struct serial_console_data *scdp)
58{
59 int n;
60 u32 reg_offset;
61
62 if (dt_get_virtual_reg(node: devp, addr: (void **)&reg_base, nres: 1) < 1) {
63 printf(fmt: "virt reg parse fail...\r\n");
64 return -1;
65 }
66
67 n = getprop(devp, name: "reg-offset", buf: &reg_offset, buflen: sizeof(reg_offset));
68 if (n == sizeof(reg_offset))
69 reg_base += be32_to_cpu(reg_offset);
70
71 n = getprop(devp, name: "reg-shift", buf: &reg_shift, buflen: sizeof(reg_shift));
72 if (n != sizeof(reg_shift))
73 reg_shift = 0;
74 else
75 reg_shift = be32_to_cpu(reg_shift);
76
77 scdp->open = ns16550_open;
78 scdp->putc = ns16550_putc;
79 scdp->getc = ns16550_getc;
80 scdp->tstc = ns16550_tstc;
81 scdp->close = NULL;
82
83 return 0;
84}
85

source code of linux/arch/powerpc/boot/ns16550.c