From patchwork Fri Jun 19 22:08:54 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Timur Tabi X-Patchwork-Id: 6649221 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 5732EC05AC for ; Fri, 19 Jun 2015 22:12:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6EB3D20875 for ; Fri, 19 Jun 2015 22:12:44 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8294220704 for ; Fri, 19 Jun 2015 22:12:43 +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 1Z64TS-0005om-AK; Fri, 19 Jun 2015 22:09:22 +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 1Z64TN-0005ni-TI for linux-arm-kernel@lists.infradead.org; Fri, 19 Jun 2015 22:09:18 +0000 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id DCC3C140926; Fri, 19 Jun 2015 22:08:56 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 486) id CF850140938; Fri, 19 Jun 2015 22:08:56 +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=-4.5 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 08826140926; Fri, 19 Jun 2015 22:08:55 +0000 (UTC) From: Timur Tabi To: catalin.marinas@arm.com, abhimany@codeaurora.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, will.deacon@arm.com Subject: [PATCH] ARM64: TTY: hvc_dcc: Add support for ARM64 dcc Date: Fri, 19 Jun 2015 17:08:54 -0500 Message-Id: <1434751734-2178-1-git-send-email-timur@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 X-Virus-Scanned: ClamAV using ClamSMTP X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150619_150917_975105_E021D7E3 X-CRM114-Status: GOOD ( 18.14 ) X-Spam-Score: -0.3 (/) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 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 | 49 ++++++++++++++++++++++++++++++++++++++++++++ drivers/tty/hvc/Kconfig | 2 +- 2 files changed, 50 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..f038d61 --- /dev/null +++ b/arch/arm64/include/asm/dcc.h @@ -0,0 +1,49 @@ +/* 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. + */ + +#include + +static inline u32 __dcc_getstatus(void) +{ + u32 __ret; + + asm volatile("mrs %0, mdccsr_el0" : "=r" (__ret) + : : "cc"); + + 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(); +} 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