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=-9.5 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,URIBL_BLOCKED,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 EE28CECE58E for ; Thu, 17 Oct 2019 17:38:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C873121D7A for ; Thu, 17 Oct 2019 17:38:18 +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="p6YI9ply" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2440754AbfJQRiQ (ORCPT ); Thu, 17 Oct 2019 13:38:16 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:37216 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2503091AbfJQRiN (ORCPT ); Thu, 17 Oct 2019 13:38:13 -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=wKgt7cxgONLSBdsnCJlQ2oLXjRoh54YqDUb57fNGjic=; b=p6YI9plypjKfw4Y6VzXrBCR5wM jcffYQjEnItN4Oa2QCS3hJFe4ZDtllKjyTxOyaaqZLKY/E8c7dfz1aUa8NOMsbYlPYVit+9CkExC9 mdY7/AZjdZWfkj/Q9tmE0zDi/okEtVjzsrCM+ELlkzgPj/Axg2Zblg2VDwlq+NLnJ5Gi/3pFA69IN GkEpr7nrrUYaptxJkX5hdtRSnwV/OfV/SUd/1mVlIBiJWXmUk2HjCkL6CBug//NgHSv3Z4ZBvXDBK bF7arsomcMtRiVWa3Hu1wHkxZ+iz32vdNKr73l46a0qA2bSbgNtgUnsAM9qES6PliB4ZFQlPHVixE o1Ohg37w==; Received: from [2001:4bb8:18c:d7b:c70:4a89:bc61:3] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iL9j0-0007u5-TW; Thu, 17 Oct 2019 17:38:11 +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 10/15] riscv: read the hart ID from mhartid on boot Date: Thu, 17 Oct 2019 19:37:38 +0200 Message-Id: <20191017173743.5430-11-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191017173743.5430-1-hch@lst.de> References: <20191017173743.5430-1-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 679e63d29edb..583784cb3a32 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