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Tobias Klauser
44a4ed4257
Enable generic earlycon support for nios2. This e.g. allows to use a 8250/16650 UART as earlycon. In order to get the earlycon, we just need to call parse_early_param() in early_init_devtree() as soon as the device tree is initially scanned. By adding an stdout-path property to the dts (done in this patch for 10m50_devboard), the earlycon can be used. In order to provide early printk support, we need to provide a dummy implementation of early_console_write(), so that arch/nios2/kernel/early_printk.c can still be compiled if neither SERIAL_ALTERA_JTAGUART_CONSOLE nor SERIAL_ALTERA_UART_CONSOLE is selected. As soon as the altera_uart and altera_jtaguart support earlycon, the entire file can be removed. Tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Acked-by: Ley Foon Tan <ley.foon.tan@intel.com>
122 lines
3.0 KiB
C
122 lines
3.0 KiB
C
/*
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* Early printk for Nios2.
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*
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* Copyright (C) 2015, Altera Corporation
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* Copyright (C) 2010, Tobias Klauser <tklauser@distanz.ch>
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* Copyright (C) 2009, Wind River Systems Inc
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* Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/console.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/io.h>
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#include <asm/prom.h>
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static unsigned long base_addr;
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#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
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#define ALTERA_JTAGUART_DATA_REG 0
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#define ALTERA_JTAGUART_CONTROL_REG 4
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#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK 0xFFFF0000
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#define ALTERA_JTAGUART_CONTROL_AC_MSK 0x00000400
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#define JUART_GET_CR() \
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__builtin_ldwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG))
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#define JUART_SET_CR(v) \
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__builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG), v)
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#define JUART_SET_TX(v) \
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__builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_DATA_REG), v)
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static void early_console_write(struct console *con, const char *s, unsigned n)
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{
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unsigned long status;
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while (n-- && *s) {
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while (((status = JUART_GET_CR())
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& ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
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#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
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if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0)
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return; /* no connection activity */
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#endif
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}
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JUART_SET_TX(*s);
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s++;
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}
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}
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#elif defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
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#define ALTERA_UART_TXDATA_REG 4
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#define ALTERA_UART_STATUS_REG 8
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#define ALTERA_UART_STATUS_TRDY 0x0040
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#define UART_GET_SR() \
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__builtin_ldwio((void *)(base_addr + ALTERA_UART_STATUS_REG))
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#define UART_SET_TX(v) \
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__builtin_stwio((void *)(base_addr + ALTERA_UART_TXDATA_REG), v)
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static void early_console_putc(char c)
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{
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while (!(UART_GET_SR() & ALTERA_UART_STATUS_TRDY))
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;
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UART_SET_TX(c);
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}
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static void early_console_write(struct console *con, const char *s, unsigned n)
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{
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while (n-- && *s) {
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early_console_putc(*s);
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if (*s == '\n')
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early_console_putc('\r');
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s++;
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}
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}
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#else
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static void early_console_write(struct console *con, const char *s, unsigned n)
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{
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}
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#endif
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static struct console early_console_prom = {
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.name = "early",
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.write = early_console_write,
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.flags = CON_PRINTBUFFER | CON_BOOT,
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.index = -1
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};
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void __init setup_early_printk(void)
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{
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#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) || \
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defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
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base_addr = of_early_console();
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#else
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base_addr = 0;
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#endif
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if (!base_addr)
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return;
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#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
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/* Clear activity bit so BYPASS doesn't stall if we've used JTAG for
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* downloading the kernel. This might cause early data to be lost even
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* if the JTAG terminal is running.
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*/
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JUART_SET_CR(JUART_GET_CR() | ALTERA_JTAGUART_CONTROL_AC_MSK);
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#endif
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early_console = &early_console_prom;
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register_console(early_console);
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pr_info("early_console initialized at 0x%08lx\n", base_addr);
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}
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