From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 405C0C3A5A2 for ; Tue, 3 Sep 2019 09:33:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 11DEA22DBF for ; Tue, 3 Sep 2019 09:33:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="OU8nQSE8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728791AbfICJdY (ORCPT ); Tue, 3 Sep 2019 05:33:24 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:58092 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728767AbfICJdV (ORCPT ); Tue, 3 Sep 2019 05:33:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Uzm4eWZCJ+haezvkDSCeISrWp8bcgIBFtwd0yXT5PFo=; b=OU8nQSE85t38dYFfEFS0jopx59 UbpU0DL1IP3oM/BKNCc8aX5x20jf4Eyg28PmrAr2JJ1CHIcQrLHvlLmK6SXlZPDy3Strcc7alZwwg 3GI/h0dWkg4cY0BRzF3jH+JfI/6VRT0/SIpUj+rdeP1tc9SUEn420gnuGCYzukzAayGDkzii7kQDE pDkuZ+LU/S8nQIjTxDFQxy+muzPZNopSNt4CUBP0u6nTkpbfHwb35XUlydj2666/YTPhBlGTitTaU EqrjUFESUYRuS+aie3FX6ba/1XY/RtT19bUtwpgKw0cuaU2uOkwS8MKn3meGtHFoAm0fIc2JTTHPw qeCr6DeQ==; Received: from clnet-p19-102.ikbnet.co.at ([83.175.77.102] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1i55Bf-0004nW-1q; Tue, 03 Sep 2019 09:33:19 +0000 From: Christoph Hellwig To: Palmer Dabbelt , Paul Walmsley Cc: Damien Le Moal , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Damien Le Moal , Atish Patra Subject: [PATCH 15/20] riscv: read the hart ID from mhartid on boot Date: Tue, 3 Sep 2019 11:32:34 +0200 Message-Id: <20190903093239.21278-16-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190903093239.21278-1-hch@lst.de> References: <20190903093239.21278-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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/include/asm/csr.h | 1 + arch/riscv/kernel/head.S | 8 ++++++++ 2 files changed, 9 insertions(+) diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h index 0dae5c361f29..d0b5113e1a54 100644 --- a/arch/riscv/include/asm/csr.h +++ b/arch/riscv/include/asm/csr.h @@ -81,6 +81,7 @@ #define SIE_SEIE (_AC(0x1, UL) << IRQ_S_EXT) /* symbolic CSR names: */ +#define CSR_MHARTID 0xf14 #define CSR_MSTATUS 0x300 #define CSR_MIE 0x304 #define CSR_MTVEC 0x305 diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index bb96bb7b95d2..e0350499d7a4 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -50,6 +50,14 @@ _start_kernel: csrw CSR_XIE, zero csrw CSR_XIP, zero +#ifdef CONFIG_RISCV_M_MODE + /* + * The hartid in a0 is expected later on, and we have no firmware + * to hand it to us. + */ + csrr a0, CSR_MHARTID +#endif + /* Load the global pointer */ .option push .option norelax -- 2.20.1