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 
31 static unsigned char *reg_base;
32 static u32 reg_shift;
33 
ns16550_open(void)34 static int ns16550_open(void)
35 {
36 	out_8(reg_base + (UART_FCR << reg_shift), 0x06);
37 	return 0;
38 }
39 
ns16550_putc(unsigned char c)40 static void ns16550_putc(unsigned char c)
41 {
42 	while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
43 	out_8(reg_base, c);
44 }
45 
ns16550_getc(void)46 static unsigned char ns16550_getc(void)
47 {
48 	while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
49 	return in_8(reg_base);
50 }
51 
ns16550_tstc(void)52 static u8 ns16550_tstc(void)
53 {
54 	return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
55 }
56 
ns16550_console_init(void * devp,struct serial_console_data * scdp)57 int 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(devp, (void **)&reg_base, 1) < 1) {
63 		printf("virt reg parse fail...\r\n");
64 		return -1;
65 	}
66 
67 	n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
68 	if (n == sizeof(reg_offset))
69 		reg_base += be32_to_cpu(reg_offset);
70 
71 	n = getprop(devp, "reg-shift", &reg_shift, 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