From patchwork Mon Jun 24 05:43:04 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11012189 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B6D301805 for ; Mon, 24 Jun 2019 05:43:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A5C6A28B0B for ; Mon, 24 Jun 2019 05:43:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 97B7F28B01; Mon, 24 Jun 2019 05:43:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 51C6C28B01 for ; Mon, 24 Jun 2019 05:43:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=GT3zsxFV3eY0eMkv+Jyu6Q0yL7mOtD6uadd2tZ9cWiw=; b=Be8zwscBhsia1o WwuKGKsQaiZYEmXFu4spf3x5F/hT/jHwWR03jpIE0LDKLej9Ow2q6zAfgzPiGnRmn5IdpP+LOlToB FJrpdy/dkx1SrKV9Fm0vcrQ3/Dwg8H0gA3Eexzb4PYlqW6OFSlK8E2oPRwEbRfkgnzlu1sWoRY7x1 iVXzwCdT549wF1UFWCBpRTRBksPaQAq6TgqW9HEG28f2wn5LWasfTbcidhXAN6ns8tTB9oSV71jLD t/NjBA0jM3MqWwf74AAO2mC8RSNG+Z2bpQJeKErj3qTDOsJyD6AXsbINA33WqQDv4Ifkvm9uuL1wi vXjcNpxJ7lEpJ3BBgXNg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hfHlf-0006cj-Kr; Mon, 24 Jun 2019 05:43:51 +0000 Received: from 213-225-6-159.nat.highway.a1.net ([213.225.6.159] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hfHld-0006Xj-5S; Mon, 24 Jun 2019 05:43:49 +0000 From: Christoph Hellwig To: Palmer Dabbelt , Paul Walmsley Subject: [PATCH 10/17] riscv: read the hart ID from mhartid on boot Date: Mon, 24 Jun 2019 07:43:04 +0200 Message-Id: <20190624054311.30256-11-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190624054311.30256-1-hch@lst.de> References: <20190624054311.30256-1-hch@lst.de> MIME-Version: 1.0 X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mm@kvack.org, Damien Le Moal , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Sender: "linux-riscv" Errors-To: linux-riscv-bounces+patchwork-linux-riscv=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Damien Le Moal When in M-Mode, we can use the mhartid CSR to get the ID of the running HART. Doing so, direct M-Mode boot without firmware is possible. Signed-off-by: Damien Le Moal Signed-off-by: Christoph Hellwig Reviewed-by: Atish Patra --- arch/riscv/kernel/head.S | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index e5fa5481aa99..a4c170e41a34 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -18,6 +18,14 @@ ENTRY(_start) csrw CSR_XIE, zero csrw CSR_XIP, zero +#ifdef CONFIG_M_MODE + /* + * The hartid in a0 is expected later on, and we have no firmware + * to hand it to us. + */ + csrr a0, mhartid +#endif + /* Load the global pointer */ .option push .option norelax