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
34 static int ns16550_open(void)
35 {
36 out_8(reg_base + (UART_FCR << reg_shift), 0x06);
37 return 0;
38 }
39
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
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
52 static u8 ns16550_tstc(void)
53 {
54 return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
55 }
56
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 **)®_base, 1) < 1) {
63 printf("virt reg parse fail...\r\n");
64 return -1;
65 }
66
67 n = getprop(devp, "reg-offset", ®_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", ®_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
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