/arch/mips/ath79/early_printk.c

  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}