1// SPDX-License-Identifier: GPL-2.0
2/*
3 * RT288x/Au1xxx driver
4 */
5
6#include <linux/module.h>
7#include <linux/io.h>
8#include <linux/init.h>
9#include <linux/console.h>
10#include <linux/serial.h>
11#include <linux/serial_8250.h>
12
13#include "8250.h"
14
15#define RT288X_DL 0x28
16
17/* Au1x00/RT288x UART hardware has a weird register layout */
18static const u8 au_io_in_map[7] = {
19 [UART_RX] = 0,
20 [UART_IER] = 2,
21 [UART_IIR] = 3,
22 [UART_LCR] = 5,
23 [UART_MCR] = 6,
24 [UART_LSR] = 7,
25 [UART_MSR] = 8,
26};
27
28static const u8 au_io_out_map[5] = {
29 [UART_TX] = 1,
30 [UART_IER] = 2,
31 [UART_FCR] = 4,
32 [UART_LCR] = 5,
33 [UART_MCR] = 6,
34};
35
36static unsigned int au_serial_in(struct uart_port *p, int offset)
37{
38 if (offset >= ARRAY_SIZE(au_io_in_map))
39 return UINT_MAX;
40 offset = au_io_in_map[offset];
41
42 return __raw_readl(addr: p->membase + (offset << p->regshift));
43}
44
45static void au_serial_out(struct uart_port *p, int offset, int value)
46{
47 if (offset >= ARRAY_SIZE(au_io_out_map))
48 return;
49 offset = au_io_out_map[offset];
50
51 __raw_writel(val: value, addr: p->membase + (offset << p->regshift));
52}
53
54/* Au1x00 haven't got a standard divisor latch */
55static u32 au_serial_dl_read(struct uart_8250_port *up)
56{
57 return __raw_readl(addr: up->port.membase + RT288X_DL);
58}
59
60static void au_serial_dl_write(struct uart_8250_port *up, u32 value)
61{
62 __raw_writel(val: value, addr: up->port.membase + RT288X_DL);
63}
64
65int au_platform_setup(struct plat_serial8250_port *p)
66{
67 p->iotype = UPIO_AU;
68
69 p->serial_in = au_serial_in;
70 p->serial_out = au_serial_out;
71 p->dl_read = au_serial_dl_read;
72 p->dl_write = au_serial_dl_write;
73
74 p->mapsize = 0x1000;
75
76 p->bugs |= UART_BUG_NOMSR;
77
78 return 0;
79}
80EXPORT_SYMBOL_GPL(au_platform_setup);
81
82int rt288x_setup(struct uart_port *p)
83{
84 struct uart_8250_port *up = up_to_u8250p(up: p);
85
86 p->iotype = UPIO_AU;
87
88 p->serial_in = au_serial_in;
89 p->serial_out = au_serial_out;
90 up->dl_read = au_serial_dl_read;
91 up->dl_write = au_serial_dl_write;
92
93 p->mapsize = 0x100;
94
95 up->bugs |= UART_BUG_NOMSR;
96
97 return 0;
98}
99EXPORT_SYMBOL_GPL(rt288x_setup);
100
101#ifdef CONFIG_SERIAL_8250_CONSOLE
102static void au_putc(struct uart_port *port, unsigned char c)
103{
104 unsigned int status;
105
106 au_serial_out(p: port, UART_TX, value: c);
107
108 for (;;) {
109 status = au_serial_in(p: port, UART_LSR);
110 if (uart_lsr_tx_empty(lsr: status))
111 break;
112 cpu_relax();
113 }
114}
115
116static void au_early_serial8250_write(struct console *console,
117 const char *s, unsigned int count)
118{
119 struct earlycon_device *device = console->data;
120 struct uart_port *port = &device->port;
121
122 uart_console_write(port, s, count, putchar: au_putc);
123}
124
125static int __init early_au_setup(struct earlycon_device *dev, const char *opt)
126{
127 rt288x_setup(&dev->port);
128 dev->con->write = au_early_serial8250_write;
129
130 return 0;
131}
132OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup);
133#endif
134
135MODULE_DESCRIPTION("RT288x/Au1xxx UART driver");
136MODULE_LICENSE("GPL");
137

source code of linux/drivers/tty/serial/8250/8250_rt288x.c