1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 *  Copyright (C) 2011-2012 Gabor Juhos <juhosg@openwrt.org>
5 */
6
7#include <linux/io.h>
8#include <linux/serial_reg.h>
9
10#include <asm/addrspace.h>
11#include <asm/setup.h>
12
13#ifdef CONFIG_SOC_RT288X
14#define EARLY_UART_BASE		0x300c00
15#define CHIPID_BASE		0x300004
16#elif defined(CONFIG_SOC_MT7621)
17#define EARLY_UART_BASE		0x1E000c00
18#define CHIPID_BASE		0x1E000004
19#else
20#define EARLY_UART_BASE		0x10000c00
21#define CHIPID_BASE		0x10000004
22#endif
23
24#define MT7628_CHIP_NAME1	0x20203832
25
26#define UART_REG_TX		0x04
27#define UART_REG_LCR		0x0c
28#define UART_REG_LSR		0x14
29#define UART_REG_LSR_RT2880	0x1c
30
31static __iomem void *uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE);
32static __iomem void *chipid_membase = (__iomem void *) KSEG1ADDR(CHIPID_BASE);
33static int init_complete;
34
35static inline void uart_w32(u32 val, unsigned reg)
36{
37	__raw_writel(val, uart_membase + reg);
38}
39
40static inline u32 uart_r32(unsigned reg)
41{
42	return __raw_readl(uart_membase + reg);
43}
44
45static inline int soc_is_mt7628(void)
46{
47	return IS_ENABLED(CONFIG_SOC_MT7620) &&
48		(__raw_readl(chipid_membase) == MT7628_CHIP_NAME1);
49}
50
51static void find_uart_base(void)
52{
53	int i;
54
55	if (!soc_is_mt7628())
56		return;
57
58	for (i = 0; i < 3; i++) {
59		u32 reg = uart_r32(UART_REG_LCR + (0x100 * i));
60
61		if (!reg)
62			continue;
63
64		uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE +
65							  (0x100 * i));
66		break;
67	}
68}
69
70void prom_putchar(char ch)
71{
72	if (!init_complete) {
73		find_uart_base();
74		init_complete = 1;
75	}
76
77	if (IS_ENABLED(CONFIG_SOC_MT7621) || soc_is_mt7628()) {
78		uart_w32((unsigned char)ch, UART_TX);
79		while ((uart_r32(UART_REG_LSR) & UART_LSR_THRE) == 0)
80			;
81	} else {
82		while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0)
83			;
84		uart_w32((unsigned char)ch, UART_REG_TX);
85		while ((uart_r32(UART_REG_LSR_RT2880) & UART_LSR_THRE) == 0)
86			;
87	}
88}
89