From patchwork Mon Sep 6 13:40:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Delevoryas X-Patchwork-Id: 1524968 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.a=rsa-sha256 header.s=facebook header.b=Sfr0C4ti; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4H38h34jM7z9sVw for ; Mon, 6 Sep 2021 23:41:39 +1000 (AEST) Received: from localhost ([::1]:44232 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mNEsT-0001EB-EO for incoming@patchwork.ozlabs.org; Mon, 06 Sep 2021 09:41:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35256) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mNErR-0000M9-RV for qemu-devel@nongnu.org; Mon, 06 Sep 2021 09:40:35 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:22884 helo=mx0a-00082601.pphosted.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mNErP-0006jS-S1 for qemu-devel@nongnu.org; Mon, 06 Sep 2021 09:40:33 -0400 Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.16.0.43/8.16.0.43) with SMTP id 186DZ5pL014829 for ; Mon, 6 Sep 2021 06:40:30 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : content-type : content-transfer-encoding : mime-version; s=facebook; bh=7hX8pcfClyecpQ+u2ryVt37NGwkCMaGiDqwps6yjoeo=; b=Sfr0C4tiFuVLb4HBBp7d1y8jknOLIxDb2tgwj8A5hyYTYMpTamG7vDRwX0d8ooqrhJWS xbzM7Q4ZpWXf3u3x03PmH9KFnCjRu8jR+H2oQIxvFkWI+4sLB61YRDkyRZ6vm4Ot77HB PsPKV6/F81y8AUQFK39e3C6jK5sJp3Theto= Received: from mail.thefacebook.com ([163.114.132.120]) by m0001303.ppops.net with ESMTP id 3awgun9egp-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 06 Sep 2021 06:40:29 -0700 Received: from intmgw003.48.prn1.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:11d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.14; Mon, 6 Sep 2021 06:40:27 -0700 Received: by devvm660.prn0.facebook.com (Postfix, from userid 385188) id 564731ACBBDB; Mon, 6 Sep 2021 06:40:24 -0700 (PDT) From: To: CC: , , , , , Peter Delevoryas Subject: [PATCH v2 1/1] hw/arm/aspeed: Initialize AST2600 UART clock selection registers Date: Mon, 6 Sep 2021 06:40:23 -0700 Message-ID: <20210906134023.3711031-2-pdel@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210906134023.3711031-1-pdel@fb.com> References: <20210906134023.3711031-1-pdel@fb.com> X-FB-Internal: Safe X-FB-Source: Intern X-Proofpoint-GUID: xY9OEadA6vcwW9URUYBwBXfs6QM8NHfe X-Proofpoint-ORIG-GUID: xY9OEadA6vcwW9URUYBwBXfs6QM8NHfe X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-09-06_06:2021-09-03, 2021-09-06 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 suspectscore=0 lowpriorityscore=0 spamscore=0 phishscore=0 malwarescore=0 adultscore=0 mlxlogscore=999 impostorscore=0 priorityscore=1501 clxscore=1015 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2108310000 definitions=main-2109060086 X-FB-Internal: deliver Received-SPF: pass client-ip=67.231.153.30; envelope-from=prvs=888312a924=pdel@fb.com; helo=mx0a-00082601.pphosted.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.391, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Peter Delevoryas UART5 is typically used as the default debug UART on the AST2600, but UART1 is also designed to be a debug UART. All the AST2600 UART's have semi-configurable clock rates through registers in the System Control Unit (SCU), but only UART5 works out of the box with zero-initialized values. The rest of the UART's expect a few of the registers to be initialized to non-zero values, or else the clock rate calculation will yield zero or undefined (due to a divide-by-zero). For reference, the U-Boot clock rate driver here shows the calculation: https://github.com/facebook/openbmc-uboot/blob/15f7e0dc01d8/drivers/clk/aspeed/clk_ast2600.c#L357 To summarize, UART5 allows selection from 4 rates: 24 MHz, 192 MHz, 24 / 13 MHz, and 192 / 13 MHz. The other UART's allow selecting either the "low" rate (UARTCLK) or the "high" rate (HUARTCLK). UARTCLK and HUARTCLK are configurable themselves: UARTCLK = UXCLK * R / (N * 2) HUARTCLK = HUXCLK * HR / (HN * 2) UXCLK and HUXCLK are also configurable, and depend on the APLL and/or HPLL clock rates, which also derive from complicated calculations. Long story short, there's lots of multiplication and division from configurable registers, and most of these registers are zero-initialized in QEMU, which at best is unexpected and at worst causes this clock rate driver to hang from divide-by-zero's. This can also be difficult to diagnose, because it may cause U-Boot to hang before serial console initialization completes, requiring intervention from gdb. This change just initializes all of these registers with default values from the datasheet. To test this, I used Facebook's AST2600 OpenBMC image for "fuji", with the following diff applied (because fuji uses UART1 for console output, not UART5). @@ -323,8 +323,8 @@ static void aspeed_soc_ast2600_realize(DeviceState *dev, Error **errp) } /* UART - attach an 8250 to the IO space as our UART5 */ - serial_mm_init(get_system_memory(), sc->memmap[ASPEED_DEV_UART5], 2, - aspeed_soc_get_irq(s, ASPEED_DEV_UART5), + serial_mm_init(get_system_memory(), sc->memmap[ASPEED_DEV_UART1], 2, + aspeed_soc_get_irq(s, ASPEED_DEV_UART1), 38400, serial_hd(0), DEVICE_LITTLE_ENDIAN); /* I2C */ Without these clock rate registers being initialized, U-Boot hangs in the clock rate driver from a divide-by-zero, because the UART1 clock rate register reads return zero, and there's no console output. After initializing them with default values, fuji boots successfully. Signed-off-by: Peter Delevoryas Reviewed-by: Joel Stanley --- hw/misc/aspeed_scu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/misc/aspeed_scu.c b/hw/misc/aspeed_scu.c index 05edebedeb..a95dca65f2 100644 --- a/hw/misc/aspeed_scu.c +++ b/hw/misc/aspeed_scu.c @@ -119,6 +119,8 @@ #define AST2600_CLK_SEL3 TO_REG(0x308) #define AST2600_CLK_SEL4 TO_REG(0x310) #define AST2600_CLK_SEL5 TO_REG(0x314) +#define AST2600_UARTCLK_PARAM TO_REG(0x338) +#define AST2600_HUARTCLK_PARAM TO_REG(0x33C) #define AST2600_HW_STRAP1 TO_REG(0x500) #define AST2600_HW_STRAP1_CLR TO_REG(0x504) #define AST2600_HW_STRAP1_PROT TO_REG(0x508) @@ -681,6 +683,8 @@ static const uint32_t ast2600_a3_resets[ASPEED_AST2600_SCU_NR_REGS] = { [AST2600_CLK_SEL3] = 0x00000000, [AST2600_CLK_SEL4] = 0xF3F40000, [AST2600_CLK_SEL5] = 0x30000000, + [AST2600_UARTCLK_PARAM] = 0x00014506, + [AST2600_HUARTCLK_PARAM] = 0x000145C0, [AST2600_CHIP_ID0] = 0x1234ABCD, [AST2600_CHIP_ID1] = 0x88884444, };