From patchwork Wed Aug 19 23:02:49 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Timur Tabi X-Patchwork-Id: 7039851 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E0D6A9F358 for ; Wed, 19 Aug 2015 23:05:11 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 144842082F for ; Wed, 19 Aug 2015 23:05:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1AF1E2081C for ; Wed, 19 Aug 2015 23:05:10 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZSCOH-0004de-Ua; Wed, 19 Aug 2015 23:03:29 +0000 Received: from smtp.codeaurora.org ([198.145.29.96]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZSCO2-0004XS-H9 for linux-arm-kernel@lists.infradead.org; Wed, 19 Aug 2015 23:03:15 +0000 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 60020141061; Wed, 19 Aug 2015 23:02:54 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id 4EBF1141064; Wed, 19 Aug 2015 23:02:54 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-4.8 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from timur-ubuntu.qualcomm.com (rrcs-67-52-129-61.west.biz.rr.com [67.52.129.61]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: timur@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 4DD96141061; Wed, 19 Aug 2015 23:02:53 +0000 (UTC) From: Timur Tabi To: Will Deacon , Dave Martin , Stephen Boyd , linux-arm-kernel@lists.infradead.org, abhimany@codeaurora.org Subject: [PATCH 2/3] [v5] ARM64: TTY: hvc_dcc: Add support for ARM64 dcc Date: Wed, 19 Aug 2015 18:02:49 -0500 Message-Id: <1440025370-9519-2-git-send-email-timur@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1440025370-9519-1-git-send-email-timur@codeaurora.org> References: <1440025370-9519-1-git-send-email-timur@codeaurora.org> X-Virus-Scanned: ClamAV using ClamSMTP X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150819_160314_656511_CF8C06E9 X-CRM114-Status: GOOD ( 19.29 ) X-Spam-Score: -2.5 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 | 55 ++++++++++++++++++++++++++++++++++++++++++++ drivers/tty/hvc/Kconfig | 2 +- 2 files changed, 56 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..65e0190 --- /dev/null +++ b/arch/arm64/include/asm/dcc.h @@ -0,0 +1,55 @@ +/* Copyright (c) 2014-2015 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) +{ + /* + * The typecast is to make absolutely certain that 'c' is + * zero-extended. + */ + asm volatile("msr dbgdtrtx_el0, %0" + : : "r" ((unsigned long)(unsigned char)c)); + isb(); +} + +#endif diff --git a/drivers/tty/hvc/Kconfig b/drivers/tty/hvc/Kconfig index 2509d05..574da15 100644 --- a/drivers/tty/hvc/Kconfig +++ b/drivers/tty/hvc/Kconfig @@ -81,7 +81,7 @@ 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