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_reg.h>
12#include <asm/addrspace.h>
13#include <asm/setup.h>
14
15#include <asm/mach-ath79/ath79.h>
16#include <asm/mach-ath79/ar71xx_regs.h>
17#include <asm/mach-ath79/ar933x_uart.h>
18
19static void (*_prom_putchar)(char);
20
21static inline void prom_putchar_wait(void __iomem *reg, u32 mask, u32 val)
22{
23	u32 t;
24
25	do {
26		t = __raw_readl(reg);
27		if ((t & mask) == val)
28			break;
29	} while (1);
30}
31
32#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
33
34static void prom_putchar_ar71xx(char ch)
35{
36	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));
37
38	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
39	__raw_writel((unsigned char)ch, base + UART_TX * 4);
40	prom_putchar_wait(base + UART_LSR * 4, BOTH_EMPTY, BOTH_EMPTY);
41}
42
43static void prom_putchar_ar933x(char ch)
44{
45	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));
46
47	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
48			  AR933X_UART_DATA_TX_CSR);
49	__raw_writel(AR933X_UART_DATA_TX_CSR | (unsigned char)ch,
50		     base + AR933X_UART_DATA_REG);
51	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR,
52			  AR933X_UART_DATA_TX_CSR);
53}
54
55static void prom_putchar_dummy(char ch)
56{
57	/* nothing to do */
58}
59
60static void prom_enable_uart(u32 id)
61{
62	void __iomem *gpio_base;
63	u32 uart_en;
64	u32 t;
65
66	switch (id) {
67	case REV_ID_MAJOR_AR71XX:
68		uart_en = AR71XX_GPIO_FUNC_UART_EN;
69		break;
70
71	case REV_ID_MAJOR_AR7240:
72	case REV_ID_MAJOR_AR7241:
73	case REV_ID_MAJOR_AR7242:
74		uart_en = AR724X_GPIO_FUNC_UART_EN;
75		break;
76
77	case REV_ID_MAJOR_AR913X:
78		uart_en = AR913X_GPIO_FUNC_UART_EN;
79		break;
80
81	case REV_ID_MAJOR_AR9330:
82	case REV_ID_MAJOR_AR9331:
83		uart_en = AR933X_GPIO_FUNC_UART_EN;
84		break;
85
86	case REV_ID_MAJOR_AR9341:
87	case REV_ID_MAJOR_AR9342:
88	case REV_ID_MAJOR_AR9344:
89		/* TODO */
90	default:
91		return;
92	}
93
94	gpio_base = (void __iomem *)KSEG1ADDR(AR71XX_GPIO_BASE);
95	t = __raw_readl(gpio_base + AR71XX_GPIO_REG_FUNC);
96	t |= uart_en;
97	__raw_writel(t, gpio_base + AR71XX_GPIO_REG_FUNC);
98}
99
100static void prom_putchar_init(void)
101{
102	void __iomem *base;
103	u32 id;
104
105	base = (void __iomem *)(KSEG1ADDR(AR71XX_RESET_BASE));
106	id = __raw_readl(base + AR71XX_RESET_REG_REV_ID);
107	id &= REV_ID_MAJOR_MASK;
108
109	switch (id) {
110	case REV_ID_MAJOR_AR71XX:
111	case REV_ID_MAJOR_AR7240:
112	case REV_ID_MAJOR_AR7241:
113	case REV_ID_MAJOR_AR7242:
114	case REV_ID_MAJOR_AR913X:
115	case REV_ID_MAJOR_AR9341:
116	case REV_ID_MAJOR_AR9342:
117	case REV_ID_MAJOR_AR9344:
118	case REV_ID_MAJOR_QCA9533:
119	case REV_ID_MAJOR_QCA9533_V2:
120	case REV_ID_MAJOR_QCA9556:
121	case REV_ID_MAJOR_QCA9558:
122	case REV_ID_MAJOR_TP9343:
123	case REV_ID_MAJOR_QCA956X:
124		_prom_putchar = prom_putchar_ar71xx;
125		break;
126
127	case REV_ID_MAJOR_AR9330:
128	case REV_ID_MAJOR_AR9331:
129		_prom_putchar = prom_putchar_ar933x;
130		break;
131
132	default:
133		_prom_putchar = prom_putchar_dummy;
134		return;
135	}
136
137	prom_enable_uart(id);
138}
139
140void prom_putchar(char ch)
141{
142	if (!_prom_putchar)
143		prom_putchar_init();
144
145	_prom_putchar(ch);
146}
147