arch/mips/pic32/pic32mzda/early_console.c

Source file repositories/reference/linux-study-clean/arch/mips/pic32/pic32mzda/early_console.c

File Facts

System
Linux kernel
Corpus path
arch/mips/pic32/pic32mzda/early_console.c
Extension
.c
Size
3212 bytes
Lines
163
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
/*
 * Joshua Henderson <joshua.henderson@microchip.com>
 * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
 */
#include <linux/io.h>
#include <linux/platform_data/pic32.h>
#include <asm/fw/fw.h>
#include <asm/setup.h>

#include "pic32mzda.h"
#include "early_pin.h"

/* Default early console parameters */
#define EARLY_CONSOLE_PORT	1
#define EARLY_CONSOLE_BAUDRATE	115200

#define UART_ENABLE		BIT(15)
#define UART_ENABLE_RX		BIT(12)
#define UART_ENABLE_TX		BIT(10)
#define UART_TX_FULL		BIT(9)

/* UART1(x == 0) - UART6(x == 5) */
#define UART_BASE(x)	((x) * 0x0200)
#define U_MODE(x)	UART_BASE(x)
#define U_STA(x)	(UART_BASE(x) + 0x10)
#define U_TXR(x)	(UART_BASE(x) + 0x20)
#define U_BRG(x)	(UART_BASE(x) + 0x40)

static void __iomem *uart_base;
static int console_port = -1;

static int __init configure_uart_pins(int port)
{
	switch (port) {
	case 1:
		pic32_pps_input(IN_FUNC_U2RX, IN_RPB0);
		pic32_pps_output(OUT_FUNC_U2TX, OUT_RPG9);
		break;
	case 5:
		pic32_pps_input(IN_FUNC_U6RX, IN_RPD0);
		pic32_pps_output(OUT_FUNC_U6TX, OUT_RPB8);
		break;
	default:
		return -1;
	}

	return 0;
}

static void __init configure_uart(int port, int baud)
{
	u32 pbclk;

	pbclk = pic32_get_pbclk(2);

	__raw_writel(0, uart_base + U_MODE(port));
	__raw_writel(((pbclk / baud) / 16) - 1, uart_base + U_BRG(port));
	__raw_writel(UART_ENABLE, uart_base + U_MODE(port));
	__raw_writel(UART_ENABLE_TX | UART_ENABLE_RX,
		     uart_base + PIC32_SET(U_STA(port)));
}

static void __init setup_early_console(int port, int baud)
{
	if (configure_uart_pins(port))
		return;

	console_port = port;
	configure_uart(console_port, baud);
}

static char * __init pic32_getcmdline(void)
{
	/*
	 * arch_mem_init() has not been called yet, so we don't have a real
	 * command line setup if using CONFIG_CMDLINE_BOOL.
	 */
#ifdef CONFIG_CMDLINE_OVERRIDE
	return CONFIG_CMDLINE;
#else
	return fw_getcmdline();
#endif
}

static int __init get_port_from_cmdline(char *arch_cmdline)
{
	char *s;
	int port = -1;

Annotation

Implementation Notes