drivers: char: hvc: add arm JTAG DCC console support (16c63f8e) · Commits · 戴 / test

drivers/char/Kconfig

+9 −0

Original line number	Diff line number	Diff line
		@@ -682,6 +682,15 @@ config HVC_UDBG
		select HVC_DRIVER
		default n

		config HVC_DCC
		bool "ARM JTAG DCC console"
		depends on ARM
		select HVC_DRIVER
		help
		This console uses the JTAG DCC on ARM to create a console under the HVC
		driver. This console is used through a JTAG only on ARM. If you don't have
		a JTAG then you probably don't want this option.

		config VIRTIO_CONSOLE
		tristate "Virtio console"
		depends on VIRTIO

drivers/char/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -34,6 +34,7 @@ obj-$(CONFIG_HVC_CONSOLE) += hvc_vio.o hvsi.o
		obj-$(CONFIG_HVC_ISERIES) += hvc_iseries.o
		obj-$(CONFIG_HVC_RTAS) += hvc_rtas.o
		obj-$(CONFIG_HVC_TILE) += hvc_tile.o
		obj-$(CONFIG_HVC_DCC) += hvc_dcc.o
		obj-$(CONFIG_HVC_BEAT) += hvc_beat.o
		obj-$(CONFIG_HVC_DRIVER) += hvc_console.o
		obj-$(CONFIG_HVC_IRQ) += hvc_irq.o

drivers/char/hvc_dcc.c

0 → 100644

+133 −0

Original line number	Diff line number	Diff line
		/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 and
		* only version 2 as published by the Free Software Foundation.
		*
		* This program is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*
		* You should have received a copy of the GNU General Public License
		* along with this program; if not, write to the Free Software
		* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
		* 02110-1301, USA.
		*/

		#include <linux/console.h>
		#include <linux/delay.h>
		#include <linux/err.h>
		#include <linux/init.h>
		#include <linux/moduleparam.h>
		#include <linux/types.h>

		#include <asm/processor.h>

		#include "hvc_console.h"

		/* DCC Status Bits */
		#define DCC_STATUS_RX (1 << 30)
		#define DCC_STATUS_TX (1 << 29)

		static inline u32 __dcc_getstatus(void)
		{
		u32 __ret;

		asm("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg"
		: "=r" (__ret) : : "cc");

		return __ret;
		}


		#if defined(CONFIG_CPU_V7)
		static inline char __dcc_getchar(void)
		{
		char __c;

		asm("get_wait: mrc p14, 0, pc, c0, c1, 0 \n\
		bne get_wait \n\
		mrc p14, 0, %0, c0, c5, 0 @ read comms data reg"
		: "=r" (__c) : : "cc");

		return __c;
		}
		#else
		static inline char __dcc_getchar(void)
		{
		char __c;

		asm("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg"
		: "=r" (__c));

		return __c;
		}
		#endif

		#if defined(CONFIG_CPU_V7)
		static inline void __dcc_putchar(char c)
		{
		asm("put_wait: mrc p14, 0, pc, c0, c1, 0 \n\
		bcs put_wait \n\
		mcr p14, 0, %0, c0, c5, 0 "
		: : "r" (c) : "cc");
		}
		#else
		static inline void __dcc_putchar(char c)
		{
		asm("mcr p14, 0, %0, c0, c5, 0 @ write a char"
		: /* no output register */
		: "r" (c));
		}
		#endif

		static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
		{
		int i;

		for (i = 0; i < count; i++) {
		while (__dcc_getstatus() & DCC_STATUS_TX)
		cpu_relax();

		__dcc_putchar((char)(buf[i] & 0xFF));
		}

		return count;
		}

		static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
		{
		int i;

		for (i = 0; i < count; ++i) {
		int c = -1;

		if (__dcc_getstatus() & DCC_STATUS_RX)
		c = __dcc_getchar();
		if (c < 0)
		break;
		buf[i] = c;
		}

		return i;
		}

		static const struct hv_ops hvc_dcc_get_put_ops = {
		.get_chars = hvc_dcc_get_chars,
		.put_chars = hvc_dcc_put_chars,
		};

		static int __init hvc_dcc_console_init(void)
		{
		hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
		return 0;
		}
		console_initcall(hvc_dcc_console_init);

		static int __init hvc_dcc_init(void)
		{
		hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
		return 0;
		}
		device_initcall(hvc_dcc_init);

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