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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 8CCD4C33CB2 for ; Tue, 28 Jan 2020 18:22:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 722E922522 for ; Tue, 28 Jan 2020 18:22:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726750AbgA1SWI (ORCPT ); Tue, 28 Jan 2020 13:22:08 -0500 Received: from lhrrgout.huawei.com ([185.176.76.210]:2323 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726276AbgA1SWI (ORCPT ); Tue, 28 Jan 2020 13:22:08 -0500 Received: from LHREML714-CAH.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id BBBB14C99F5943C6C623; Tue, 28 Jan 2020 18:22:05 +0000 (GMT) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by LHREML714-CAH.china.huawei.com (10.201.108.37) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 28 Jan 2020 18:22:05 +0000 Received: from [127.0.0.1] (10.210.167.110) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Tue, 28 Jan 2020 18:22:04 +0000 Subject: Re: [PATCH RFC 2/2] soc: Add a basic ACPI generic driver To: Olof Johansson CC: "Rafael J. Wysocki" , Len Brown , , Arnd Bergmann , "Linux Kernel Mailing List" , , Hanjun Guo , Greg Kroah-Hartman References: <1580210059-199540-1-git-send-email-john.garry@huawei.com> <1580210059-199540-3-git-send-email-john.garry@huawei.com> From: John Garry Message-ID: <4c6462e3-e368-bd9f-260f-e8351c85bcc2@huawei.com> Date: Tue, 28 Jan 2020 18:22:02 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.210.167.110] X-ClientProxiedBy: lhreml712-chm.china.huawei.com (10.201.108.63) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28/01/2020 17:51, Olof Johansson wrote: > Hi, > > On Tue, Jan 28, 2020 at 3:18 AM John Garry wrote: >> Hi Olof, >> Add a generic driver for platforms which populate their ACPI PPTT >> processor package ID Type Structure according to suggestion in the ACPI >> spec - see ACPI 6.2, section 5.2.29.3 ID structure Type 2. >> >> The soc_id is from member LEVEL_2_ID. >> >> For this, we need to use a whitelist of platforms which are known to >> populate the structure as suggested. >> >> For now, only the vendor and soc_id fields are exposed. >> >> Signed-off-by: John Garry >> --- >> drivers/soc/Makefile | 1 + >> drivers/soc/acpi_generic.c | 102 +++++++++++++++++++++++++++++++++++++ >> 2 files changed, 103 insertions(+) >> create mode 100644 drivers/soc/acpi_generic.c >> >> diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile >> index 8b49d782a1ab..2a59a30a22cd 100644 >> --- a/drivers/soc/Makefile >> +++ b/drivers/soc/Makefile >> @@ -3,6 +3,7 @@ >> # Makefile for the Linux Kernel SOC specific device drivers. >> # >> >> +obj-$(CONFIG_ACPI_PPTT) += acpi_generic.o >> obj-$(CONFIG_ARCH_ACTIONS) += actions/ >> obj-$(CONFIG_SOC_ASPEED) += aspeed/ >> obj-$(CONFIG_ARCH_AT91) += atmel/ > > Based on everything I've seen so far, this should go under drivers/acpi instead. soc drivers seem to live in drivers/soc (non-arm32, anyway), so I decided on this location. But drivers/acpi would also seem reasonable now. > >> diff --git a/drivers/soc/acpi_generic.c b/drivers/soc/acpi_generic.c >> new file mode 100644 >> index 000000000000..34a1f5f8e063 >> --- /dev/null >> +++ b/drivers/soc/acpi_generic.c >> @@ -0,0 +1,102 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * Copyright (c) John Garry, john.garry@huawei.com >> + */ >> + >> +#define pr_fmt(fmt) "SOC ACPI GENERIC: " fmt >> + >> +#include >> +#include >> + >> +/* >> + * Known platforms that fill in PPTT package ID structures according to >> + * ACPI spec examples, that being: >> + * - Custom driver attribute is in ID Type Structure VENDOR_ID member >> + * - SoC id is in ID Type Structure LEVEL_2_ID member >> + * See ACPI SPEC 6.2 Table 5-154 for PPTT ID Type Structure >> + */ >> +static struct acpi_platform_list plat_list[] = { >> + {"HISI ", "HIP08 ", 0, ACPI_SIG_PPTT, all_versions}, >> + { } /* End */ >> +}; > > As others have said, this will become a mess over time, and will > require changes for every new platform. Which, unfortunately, is > exactly what ACPI is supposed to provide relief from by making > standardized platforms... standardized. > Right, and I think that it can be dropped. As discussed with Sudeep, I was concerned how this PPTT ID structure could be interpreted, and had a whitelist as a conservative approach. >> + >> +struct acpi_generic_soc_struct { >> + struct soc_device_attribute dev_attr; >> + u32 vendor; >> +}; >> + >> +static ssize_t vendor_show(struct device *dev, >> + struct device_attribute *attr, >> + char *buf) >> +{ >> + struct acpi_generic_soc_struct *soc = dev_get_drvdata(dev); >> + u8 vendor_id[5] = {}; >> + >> + *(u32 *)vendor_id = soc->vendor; >> + >> + return sprintf(buf, "%s\n", vendor_id); >> +} >> + >> +static DEVICE_ATTR_RO(vendor); >> + >> +static __init int soc_acpi_generic_init(void) >> +{ >> + int index; >> + >> + index = acpi_match_platform_list(plat_list); >> + if (index < 0) >> + return -ENOENT; >> + >> + index = 0; >> + while (true) { >> + struct acpi_pptt_package_info info; >> + >> + if (!acpi_pptt_get_package_info(index, &info)) { >> + struct soc_device_attribute *soc_dev_attr; >> + struct acpi_generic_soc_struct *soc; >> + struct soc_device *soc_dev; >> + u8 soc_id[9] = {}; >> + >> + *(u64 *)soc_id = info.LEVEL_2_ID; >> + >> + soc = kzalloc(sizeof(*soc), GFP_KERNEL); >> + if (!soc) >> + return -ENOMEM; >> + >> + soc_dev_attr = &soc->dev_attr; >> + soc_dev_attr->soc_id = kasprintf(GFP_KERNEL, "%s", >> + soc_id); >> + if (!soc_dev_attr->soc_id) { >> + kfree(soc); >> + return -ENOMEM; >> + } >> + soc->vendor = info.vendor_id; >> + >> + soc_dev = soc_device_register(soc_dev_attr); >> + if (IS_ERR(soc_dev)) { >> + int ret = PTR_ERR(soc_dev); >> + >> + pr_info("could not register soc (%d) index=%d\n", >> + ret, index); >> + kfree(soc_dev_attr->soc_id); >> + kfree(soc); >> + return ret; >> + } >> + dev_set_drvdata(soc_device_to_device(soc_dev), soc); >> + device_create_file(soc_device_to_device(soc_dev), >> + &dev_attr_vendor); > > Hmm, this doesn't look like much of a driver to me. This looks like > the export of an attribute to userspace, and should probably be done > by ACPI core instead of creating an empty driver for it. OK, but I'm thinking that having a soc driver can be useful as it is common to DT, and so userspace only has to check a single location. And the soc driver can also cover multiple-chip systems without have to reinvent that code for ACPI core. And it saves adding a new ABI. > > This would also solve the whitelist issue -- always export this > property if it's set. If it's wrong, then the platform vendor needs to > fix it up. That's the approach that is used for other aspects of the > standardized platforms, right? We don't want to litter the kernel with > white/blacklists -- that's not a net improvement. Agreed. > > > -Olof > . Thanks, John >