From patchwork Mon Sep 25 14:48:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Wilczynski, Michal" X-Patchwork-Id: 13397927 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.93]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A45E1C295 for ; Mon, 25 Sep 2023 14:49:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1695653361; x=1727189361; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=kKM0C1N1K+zAFPffptjtDRXafSmi9wPq9IOl4rSEZ+w=; b=F/ezaepzUt1YjDf8xW+pc8wySNvqQwV/jdDRqTl2U7oFsZzUS9mRC9Fw NR4G1wtREVIeM724S7tpun3BDMGje8Dv5TVZL1hVITnvTJ2XV74FpPdZg 4oU1CpzajRjOmV40IQOAPZqxACctgtfC08v6omEe4PLDKwYyx9/g8uwIN zmQVVgpM+QhS7pf0Lbv3PaxhK6BB75+PRt6dL+HCAeGyJZA5IoJg+bpp5 OOdJCVl0USBiqi0iiK980NFQWE3pybZNuBOVt/ecPCGsczmCdGQCnmkIK 6+2W5CHhyNereDyrskPrsywj96YNWzc+yx0WRVS+UXkiJQf3e85QrKho5 w==; X-IronPort-AV: E=McAfee;i="6600,9927,10843"; a="378547989" X-IronPort-AV: E=Sophos;i="6.03,175,1694761200"; d="scan'208";a="378547989" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2023 07:49:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10843"; a="995409451" X-IronPort-AV: E=Sophos;i="6.03,175,1694761200"; d="scan'208";a="995409451" Received: from powerlab.fi.intel.com ([10.237.71.25]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2023 07:49:17 -0700 From: Michal Wilczynski To: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev Cc: rafael.j.wysocki@intel.com, andriy.shevchenko@intel.com, lenb@kernel.org, dan.j.williams@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, rui.zhang@intel.com, Michal Wilczynski , Elena Reshetova Subject: [PATCH v1 2/9] docs: firmware-guide: ACPI: Clarify ACPI bus concepts Date: Mon, 25 Sep 2023 17:48:35 +0300 Message-ID: <20230925144842.586829-3-michal.wilczynski@intel.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230925144842.586829-1-michal.wilczynski@intel.com> References: <20230925144842.586829-1-michal.wilczynski@intel.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Some devices implement ACPI driver as a way to manage devices enumerated by the ACPI. This might be confusing as a preferred way to implement a driver for devices not connected to any bus is a platform driver, as stated in the documentation. Clarify relationships between ACPI device, platform device and ACPI entries. Suggested-by: Elena Reshetova Signed-off-by: Michal Wilczynski Signed-off-by: Michal Wilczynski Signed-off-by: Rafael J. Wysocki --- Documentation/firmware-guide/acpi/enumeration.rst | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/firmware-guide/acpi/enumeration.rst b/Documentation/firmware-guide/acpi/enumeration.rst index 56d9913a3370..f56cc79a9e83 100644 --- a/Documentation/firmware-guide/acpi/enumeration.rst +++ b/Documentation/firmware-guide/acpi/enumeration.rst @@ -64,6 +64,19 @@ If the driver needs to perform more complex initialization like getting and configuring GPIOs it can get its ACPI handle and extract this information from ACPI tables. +ACPI bus +==================== + +Historically some devices not connected to any bus were represented as ACPI +devices, and had to implement ACPI driver. This is not a preferred way for new +drivers. As explained above devices not connected to any bus should implement +platform driver. ACPI device would be created during enumeration nonetheless, +and would be accessible through ACPI_COMPANION() macro, and the ACPI handle would +be accessible through ACPI_HANDLE() macro. ACPI device is meant to describe +information related to ACPI entry e.g. handle of the ACPI entry. Think - +ACPI device interfaces with the FW, and the platform device with the rest of +the system. + DMA support ===========