Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752581AbbFZSw6 (ORCPT ); Fri, 26 Jun 2015 14:52:58 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:33008 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751726AbbFZSwl (ORCPT ); Fri, 26 Jun 2015 14:52:41 -0400 From: Timur Tabi To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Shanker Donthineni , awallis@codeaurora.org, abhimany@codeaurora.org, will.deacon@arm.com, sboyd@codeaurora.org, Vipul Gandhi Subject: [PATCH 3/3] [v2] ARM64: TTY: hvc_dcc: Add support for ARM64 dcc Date: Fri, 26 Jun 2015 13:52:36 -0500 Message-Id: <1435344756-20901-3-git-send-email-timur@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1435344756-20901-1-git-send-email-timur@codeaurora.org> References: <1435344756-20901-1-git-send-email-timur@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3621 Lines: 122 From: Abhimanyu Kapur Add support for debug communications channel based hvc console for arm64 cpus. Signed-off-by: Abhimanyu Kapur Signed-off-by: Timur Tabi --- arch/arm64/include/asm/dcc.h | 52 ++++++++++++++++++++++++++++++++++++++++++++ drivers/tty/hvc/Kconfig | 2 +- drivers/tty/hvc/hvc_dcc.c | 11 ++++++++++ 3 files changed, 64 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/include/asm/dcc.h diff --git a/arch/arm64/include/asm/dcc.h b/arch/arm64/include/asm/dcc.h new file mode 100644 index 0000000..d550173 --- /dev/null +++ b/arch/arm64/include/asm/dcc.h @@ -0,0 +1,52 @@ +/* Copyright (c) 2014 The Linux Foundation. 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. + * + * A call to __dcc_getchar() or __dcc_putchar() is typically followed by + * a call to __dcc_getstatus(). We want to make sure that the CPU does + * not speculative read the DCC status before executing the read or write + * instruction. That's what the ISBs are for. + * + * The 'volatile' ensures that the compiler does not cache the status bits, + * and instead reads the DCC register every time. + */ +#ifndef __ASM_DCC_H +#define __ASM_DCC_H + +#include + +static inline u32 __dcc_getstatus(void) +{ + u32 ret; + + asm volatile("mrs %0, mdccsr_el0" : "=r" (ret)); + + return ret; +} + +static inline char __dcc_getchar(void) +{ + char c; + + asm volatile("mrs %0, dbgdtrrx_el0" : "=r" (c)); + isb(); + + return c; +} + +static inline void __dcc_putchar(char c) +{ + asm volatile("msr dbgdtrtx_el0, %0" + : /* No output register */ + : "r" (c)); + isb(); +} + +#endif diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig index 2c6883c..9a60d18 100644 --- a/drivers/tty/hvc/Kconfig +++ b/drivers/tty/hvc/Kconfig @@ -88,7 +88,7 @@ config HVC_UDBG config HVC_DCC bool "ARM JTAG DCC console" - depends on ARM + depends on ARM || ARM64 select HVC_DRIVER help This console uses the JTAG DCC on ARM to create a console under the HVC diff --git a/drivers/tty/hvc/hvc_dcc.c b/drivers/tty/hvc/hvc_dcc.c index f8b8cf2..d4c7073 100644 --- a/drivers/tty/hvc/hvc_dcc.c +++ b/drivers/tty/hvc/hvc_dcc.c @@ -226,11 +226,22 @@ static const struct hv_ops hvc_dcc_get_put_ops = { static int __init hvc_dcc_console_init(void) { int ret; +#ifdef CONFIG_ARM64 + u32 val; +#endif /* This always runs on boot core */ if (!hvc_dcc_check()) return -ENODEV; +#ifdef CONFIG_ARM64 + /* Disable user-space access to DCC */ + asm("msr mdscr_el1, %0 " + "orr %0, %0, #4096 " /* TDCC */ + "msr %0, mdscr_el1 " + : "=r" (val)); +#endif + /* Returns -1 if error */ ret = hvc_instantiate(0, 0, &hvc_dcc_get_put_ops); -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/