xref: /openbmc/linux/arch/mips/ath79/early_printk.c (revision 7effbd18) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  Atheros AR7XXX/AR9XXX SoC early printk support
4  *
5  *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
6  *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
7  */
8 
9 #include <linux/io.h>
10 #include <linux/errno.h>
11 #include <linux/serial.h>
12 #include <linux/serial_reg.h>
13 #include <asm/addrspace.h>
14 #include <asm/setup.h>
15 
16 #include <asm/mach-ath79/ath79.h>
17 #include <asm/mach-ath79/ar71xx_regs.h>
18 #include <asm/mach-ath79/ar933x_uart.h>
19 
20 static void (*_prom_putchar)(char);
21 
22 static inline void prom_putchar_wait(void __iomem *reg, u32 val)
23 {
24 	u32 t;
25 
26 	do {
27 		t = __raw_readl(reg);
28 		if ((t & val) == val)
29 			break;
30 	} while (1);
31 }
32 
33 static void prom_putchar_ar71xx(char ch)
34 {
35 	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
36 
37 	prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
38 	__raw_writel((unsigned char)ch, base + UART_TX * 4);
39 	prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
40 }
41 
42 static void prom_putchar_ar933x(char ch)
43 {
44 	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
45 
46 	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
47 	__raw_writel(AR933X_UART_DATA_TX_CSR | (unsigned char)ch,
48 		     base + AR933X_UART_DATA_REG);
49 	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
50 }
51 
52 static void prom_putchar_dummy(char ch)
53 {
54 	/* nothing to do */
55 }
56 
57 static void prom_enable_uart(u32 id)
58 {
59 	void __iomem *gpio_base;
60 	u32 uart_en;
61 	u32 t;
62 
63 	switch (id) {
64 	case REV_ID_MAJOR_AR71XX:
65 		uart_en = AR71XX_GPIO_FUNC_UART_EN;
66 		break;
67 
68 	case REV_ID_MAJOR_AR7240:
69 	case REV_ID_MAJOR_AR7241:
70 	case REV_ID_MAJOR_AR7242:
71 		uart_en = AR724X_GPIO_FUNC_UART_EN;
72 		break;
73 
74 	case REV_ID_MAJOR_AR913X:
75 		uart_en = AR913X_GPIO_FUNC_UART_EN;
76 		break;
77 
78 	case REV_ID_MAJOR_AR9330:
79 	case REV_ID_MAJOR_AR9331:
80 		uart_en = AR933X_GPIO_FUNC_UART_EN;
81 		break;
82 
83 	case REV_ID_MAJOR_AR9341:
84 	case REV_ID_MAJOR_AR9342:
85 	case REV_ID_MAJOR_AR9344:
86 		/* TODO */
87 	default:
88 		return;
89 	}
90 
91 	gpio_base = (void __iomem *)KSEG1ADDR(AR71XX_GPIO_BASE);
92 	t = __raw_readl(gpio_base + AR71XX_GPIO_REG_FUNC);
93 	t |= uart_en;
94 	__raw_writel(t, gpio_base + AR71XX_GPIO_REG_FUNC);
95 }
96 
97 static void prom_putchar_init(void)
98 {
99 	void __iomem *base;
100 	u32 id;
101 
102 	base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
103 	id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
104 	id &= REV_ID_MAJOR_MASK;
105 
106 	switch (id) {
107 	case REV_ID_MAJOR_AR71XX:
108 	case REV_ID_MAJOR_AR7240:
109 	case REV_ID_MAJOR_AR7241:
110 	case REV_ID_MAJOR_AR7242:
111 	case REV_ID_MAJOR_AR913X:
112 	case REV_ID_MAJOR_AR9341:
113 	case REV_ID_MAJOR_AR9342:
114 	case REV_ID_MAJOR_AR9344:
115 	case REV_ID_MAJOR_QCA9533:
116 	case REV_ID_MAJOR_QCA9533_V2:
117 	case REV_ID_MAJOR_QCA9556:
118 	case REV_ID_MAJOR_QCA9558:
119 	case REV_ID_MAJOR_TP9343:
120 	case REV_ID_MAJOR_QCA956X:
121 	case REV_ID_MAJOR_QCN550X:
122 		_prom_putchar = prom_putchar_ar71xx;
123 		break;
124 
125 	case REV_ID_MAJOR_AR9330:
126 	case REV_ID_MAJOR_AR9331:
127 		_prom_putchar = prom_putchar_ar933x;
128 		break;
129 
130 	default:
131 		_prom_putchar = prom_putchar_dummy;
132 		return;
133 	}
134 
135 	prom_enable_uart(id);
136 }
137 
138 void prom_putchar(char ch)
139 {
140 	if (!_prom_putchar)
141 		prom_putchar_init();
142 
143 	_prom_putchar(ch);
144 }
145