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Commit e934945d authored by James Hogan's avatar James Hogan Committed by Ralf Baechle
Browse files

MIPS, ttyFDC: Add early FDC console support 



Add support for early console of MIPS Fast Debug Channel (FDC) on
channel 1 with a call very early from the MIPS setup_arch().

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9145/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 4cebec60

arch/mips/include/asm/cdmm.h

+11 −0
Original line number Diff line number Diff line
@@ -84,4 +84,15 @@ void mips_cdmm_driver_unregister(struct mips_cdmm_driver *); 
	module_driver(__mips_cdmm_driver, mips_cdmm_driver_register, \

			mips_cdmm_driver_unregister)



/* drivers/tty/mips_ejtag_fdc.c */



#ifdef CONFIG_MIPS_EJTAG_FDC_EARLYCON

int setup_early_fdc_console(void);

#else

static inline int setup_early_fdc_console(void)

{

	return -ENODEV;

}

#endif



#endif /* __ASM_CDMM_H */

arch/mips/kernel/setup.c

+2 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <asm/bootinfo.h>

#include <asm/bugs.h>

#include <asm/cache.h>

#include <asm/cdmm.h>

#include <asm/cpu.h>

#include <asm/sections.h>

#include <asm/setup.h>
@@ -763,6 +764,7 @@ void __init setup_arch(char **cmdline_p) 
	cpu_probe();

	prom_init();



	setup_early_fdc_console();

#ifdef CONFIG_EARLY_PRINTK

	setup_early_printk();

#endif

drivers/tty/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -437,4 +437,17 @@ config MIPS_EJTAG_FDC_TTY 


	  If unsure, say N.



config MIPS_EJTAG_FDC_EARLYCON

	bool "Early FDC console"

	depends on MIPS_EJTAG_FDC_TTY

	help

	  This registers a console on FDC channel 1 very early during boot (from

	  MIPS arch code). This is useful for bring-up and debugging early boot

	  issues.



	  Do not enable unless there is a debug probe attached to drain the FDC

	  TX FIFO.



	  If unsure, say N.



endif # TTY

drivers/tty/mips_ejtag_fdc.c

+20 −0
Original line number Diff line number Diff line
@@ -69,6 +69,9 @@ 
#define REG_FDSTAT_TXE			BIT(1)	/* Tx Empty */

#define REG_FDSTAT_TXF			BIT(0)	/* Tx Full */



/* Default channel for the early console */

#define CONSOLE_CHANNEL      1



#define NUM_TTY_CHANNELS     16



#define RX_BUF_SIZE 1024
@@ -1124,3 +1127,20 @@ static int __init mips_ejtag_fdc_init_console(void) 
	return mips_ejtag_fdc_console_init(&mips_ejtag_fdc_con);

}

console_initcall(mips_ejtag_fdc_init_console);



#ifdef CONFIG_MIPS_EJTAG_FDC_EARLYCON

static struct mips_ejtag_fdc_console mips_ejtag_fdc_earlycon = {

	.cons	= {

		.name	= "early_fdc",

		.write	= mips_ejtag_fdc_console_write,

		.flags	= CON_PRINTBUFFER | CON_BOOT,

		.index	= CONSOLE_CHANNEL,

	},

	.lock	= __RAW_SPIN_LOCK_UNLOCKED(mips_ejtag_fdc_earlycon.lock),

};



int __init setup_early_fdc_console(void)

{

	return mips_ejtag_fdc_console_init(&mips_ejtag_fdc_earlycon);

}

#endif