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
31 static __iomem void *uart_membase = (__iomem void *) KSEG1ADDR(EARLY_UART_BASE);
32 static __iomem void *chipid_membase = (__iomem void *) KSEG1ADDR(CHIPID_BASE);
33 static int init_complete;
34
35 static inline void uart_w32(u32 val, unsigned reg)
36 {
37 __raw_writel(val, uart_membase + reg);
38 }
39
40 static inline u32 uart_r32(unsigned reg)
41 {
42 return __raw_readl(uart_membase + reg);
43 }
44
45 static inline int soc_is_mt7628(void)
46 {
47 return IS_ENABLED(CONFIG_SOC_MT7620) &&
48 (__raw_readl(chipid_membase) == MT7628_CHIP_NAME1);
49 }
50
51 static 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
70 void 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
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