early_console.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Joshua Henderson <joshua.henderson@microchip.com>
  4 * Copyright (C) 2015 Microchip Technology Inc.  All rights reserved.
  5 */
  6#include <asm/mach-pic32/pic32.h>
  7#include <asm/fw/fw.h>
  8#include <asm/setup.h>
  9
 10#include "pic32mzda.h"
 11#include "early_pin.h"
 12
 13/* Default early console parameters */
 14#define EARLY_CONSOLE_PORT	1
 15#define EARLY_CONSOLE_BAUDRATE	115200
 16
 17#define UART_ENABLE		BIT(15)
 18#define UART_ENABLE_RX		BIT(12)
 19#define UART_ENABLE_TX		BIT(10)
 20#define UART_TX_FULL		BIT(9)
 21
 22/* UART1(x == 0) - UART6(x == 5) */
 23#define UART_BASE(x)	((x) * 0x0200)
 24#define U_MODE(x)	UART_BASE(x)
 25#define U_STA(x)	(UART_BASE(x) + 0x10)
 26#define U_TXR(x)	(UART_BASE(x) + 0x20)
 27#define U_BRG(x)	(UART_BASE(x) + 0x40)
 28
 29static void __iomem *uart_base;
 30static int console_port = -1;
 31
 32static int __init configure_uart_pins(int port)
 33{
 34	switch (port) {
 35	case 1:
 36		pic32_pps_input(IN_FUNC_U2RX, IN_RPB0);
 37		pic32_pps_output(OUT_FUNC_U2TX, OUT_RPG9);
 38		break;
 39	case 5:
 40		pic32_pps_input(IN_FUNC_U6RX, IN_RPD0);
 41		pic32_pps_output(OUT_FUNC_U6TX, OUT_RPB8);
 42		break;
 43	default:
 44		return -1;
 45	}
 46
 47	return 0;
 48}
 49
 50static void __init configure_uart(int port, int baud)
 51{
 52	u32 pbclk;
 53
 54	pbclk = pic32_get_pbclk(2);
 55
 56	__raw_writel(0, uart_base + U_MODE(port));
 57	__raw_writel(((pbclk / baud) / 16) - 1, uart_base + U_BRG(port));
 58	__raw_writel(UART_ENABLE, uart_base + U_MODE(port));
 59	__raw_writel(UART_ENABLE_TX | UART_ENABLE_RX,
 60		     uart_base + PIC32_SET(U_STA(port)));
 61}
 62
 63static void __init setup_early_console(int port, int baud)
 64{
 65	if (configure_uart_pins(port))
 66		return;
 67
 68	console_port = port;
 69	configure_uart(console_port, baud);
 70}
 71
 72static char * __init pic32_getcmdline(void)
 73{
 74	/*
 75	 * arch_mem_init() has not been called yet, so we don't have a real
 76	 * command line setup if using CONFIG_CMDLINE_BOOL.
 77	 */
 78#ifdef CONFIG_CMDLINE_OVERRIDE
 79	return CONFIG_CMDLINE;
 80#else
 81	return fw_getcmdline();
 82#endif
 83}
 84
 85static int __init get_port_from_cmdline(char *arch_cmdline)
 86{
 87	char *s;
 88	int port = -1;
 89
 90	if (!arch_cmdline || *arch_cmdline == '\0')
 91		goto _out;
 92
 93	s = strstr(arch_cmdline, "earlyprintk=");
 94	if (s) {
 95		s = strstr(s, "ttyS");
 96		if (s)
 97			s += 4;
 98		else
 99			goto _out;
100
101		port = (*s) - '0';
102	}
103
104_out:
105	return port;
106}
107
108static int __init get_baud_from_cmdline(char *arch_cmdline)
109{
110	char *s;
111	int baud = -1;
112
113	if (!arch_cmdline || *arch_cmdline == '\0')
114		goto _out;
115
116	s = strstr(arch_cmdline, "earlyprintk=");
117	if (s) {
118		s = strstr(s, "ttyS");
119		if (s)
120			s += 6;
121		else
122			goto _out;
123
124		baud = 0;
125		while (*s >= '0' && *s <= '9')
126			baud = baud * 10 + *s++ - '0';
127	}
128
129_out:
130	return baud;
131}
132
133void __init fw_init_early_console(void)
134{
135	char *arch_cmdline = pic32_getcmdline();
136	int baud, port;
137
138	uart_base = ioremap(PIC32_BASE_UART, 0xc00);
139
140	baud = get_baud_from_cmdline(arch_cmdline);
141	port = get_port_from_cmdline(arch_cmdline);
142
143	if (port == -1)
144		port = EARLY_CONSOLE_PORT;
145
146	if (baud == -1)
147		baud = EARLY_CONSOLE_BAUDRATE;
148
149	setup_early_console(port, baud);
150}
151
152void prom_putchar(char c)
153{
154	if (console_port >= 0) {
155		while (__raw_readl(
156				uart_base + U_STA(console_port)) & UART_TX_FULL)
157			;
158
159		__raw_writel(c, uart_base + U_TXR(console_port));
160	}
161}