arch/mips/ath79/early_printk.c

Source file repositories/reference/linux-study-clean/arch/mips/ath79/early_printk.c

File Facts

System
Linux kernel
Corpus path
arch/mips/ath79/early_printk.c
Extension
.c
Size
3151 bytes
Lines
145
Domain
Architecture Layer
Bucket
arch/mips
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Atheros AR7XXX/AR9XXX SoC early printk support
 *
 *  Copyright (C) 2008-2011 Gabor Juhos <juhosg@openwrt.org>
 *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
 */

#include <linux/io.h>
#include <linux/errno.h>
#include <linux/serial.h>
#include <linux/serial_reg.h>
#include <asm/addrspace.h>
#include <asm/setup.h>

#include <asm/mach-ath79/ath79.h>
#include <asm/mach-ath79/ar71xx_regs.h>
#include <asm/mach-ath79/ar933x_uart.h>

static void (*_prom_putchar)(char);

static inline void prom_putchar_wait(void __iomem *reg, u32 val)
{
	u32 t;

	do {
		t = __raw_readl(reg);
		if ((t & val) == val)
			break;
	} while (1);
}

static void prom_putchar_ar71xx(char ch)
{
	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR71XX_UART_BASE));

	prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
	__raw_writel((unsigned char)ch, base + UART_TX * 4);
	prom_putchar_wait(base + UART_LSR * 4, UART_LSR_BOTH_EMPTY);
}

static void prom_putchar_ar933x(char ch)
{
	void __iomem *base = (void __iomem *)(KSEG1ADDR(AR933X_UART_BASE));

	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
	__raw_writel(AR933X_UART_DATA_TX_CSR | (unsigned char)ch,
		     base + AR933X_UART_DATA_REG);
	prom_putchar_wait(base + AR933X_UART_DATA_REG, AR933X_UART_DATA_TX_CSR);
}

static void prom_putchar_dummy(char ch)
{
	/* nothing to do */
}

static void prom_enable_uart(u32 id)
{
	void __iomem *gpio_base;
	u32 uart_en;
	u32 t;

	switch (id) {
	case REV_ID_MAJOR_AR71XX:
		uart_en = AR71XX_GPIO_FUNC_UART_EN;
		break;

	case REV_ID_MAJOR_AR7240:
	case REV_ID_MAJOR_AR7241:
	case REV_ID_MAJOR_AR7242:
		uart_en = AR724X_GPIO_FUNC_UART_EN;
		break;

	case REV_ID_MAJOR_AR913X:
		uart_en = AR913X_GPIO_FUNC_UART_EN;
		break;

	case REV_ID_MAJOR_AR9330:
	case REV_ID_MAJOR_AR9331:
		uart_en = AR933X_GPIO_FUNC_UART_EN;
		break;

	case REV_ID_MAJOR_AR9341:
	case REV_ID_MAJOR_AR9342:
	case REV_ID_MAJOR_AR9344:
		/* TODO */
	default:
		return;
	}

Annotation

Implementation Notes