From patchwork Fri Sep 9 20:24:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bjorn Helgaas X-Patchwork-Id: 12972148 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22049C6FA89 for ; Fri, 9 Sep 2022 20:25:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232096AbiIIUZW (ORCPT ); Fri, 9 Sep 2022 16:25:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231627AbiIIUZT (ORCPT ); Fri, 9 Sep 2022 16:25:19 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6FBAADCEB; Fri, 9 Sep 2022 13:25:17 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 81344620DB; Fri, 9 Sep 2022 20:25:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B28A5C433C1; Fri, 9 Sep 2022 20:25:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662755115; bh=H4Hvk9X1Yt7qkvWdBzft4a3QJFArMQTjPf+CJiLeiSg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N/bH2qIDnclzkBx0bhkg5Nu9Rft5zehfQWKNRgp3Eu1E2xoYYikeQaav6qI4lz4wU B9RAK05YYSjQHmX2Ap/iV828hNB8wQYt4C08QU6eRyyFkXEDf2OolFsCh5yMEUuNST 9EZhs2vcnc+3jlEKhiZiGGwBKDiwxbJuecokuVmBwrTpR28A2yxN57qddKhdha+8Oo hwZyLQ4/CpnBFp5tCUjrILT72LhSh4e3XFrTcqNWXWc1v7A0m5dI1rL5HoxkuBFdn9 mZISzZnNX6wO8BN70bfbCjOGNag9Q28lm5MlgSWtJDTGTa/dt/xcH3TVSm+kvdNn1M AaJ1HqSSfoO7Q== From: Bjorn Helgaas To: Kai-Heng Feng , Rajvi Jingar , "Rafael J . Wysocki" Cc: Koba Ko , Mika Westerberg , "David E . Box" , Sathyanarayanan Kuppuswamy , linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas Subject: [PATCH v4 3/9] PCI/PTM: Separate configuration and enable Date: Fri, 9 Sep 2022 15:24:59 -0500 Message-Id: <20220909202505.314195-4-helgaas@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220909202505.314195-1-helgaas@kernel.org> References: <20220909202505.314195-1-helgaas@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Bjorn Helgaas PTM configuration and enabling were previously mixed together: pci_ptm_init() collected granularity info and enabled PTM for Root Ports and Switch Upstream Ports; pci_enable_ptm() did the same for Endpoints. Move everything related to the PTM Capability register to pci_ptm_init() for all devices, and everything related to the PTM Control register to pci_enable_ptm(). Signed-off-by: Bjorn Helgaas --- drivers/pci/pcie/ptm.c | 104 +++++++++++++++++++---------------------- 1 file changed, 49 insertions(+), 55 deletions(-) diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c index 0df6cdfe38b4..ba1d50c965fa 100644 --- a/drivers/pci/pcie/ptm.c +++ b/drivers/pci/pcie/ptm.c @@ -99,25 +99,19 @@ static struct pci_dev *pci_upstream_ptm(struct pci_dev *dev) return NULL; } +/* + * Find the PTM Capability (if present) and extract the information we need + * to use it. + */ void pci_ptm_init(struct pci_dev *dev) { u16 ptm; - u32 cap, ctrl; - u8 local_clock; + u32 cap; struct pci_dev *ups; if (!pci_is_pcie(dev)) return; - /* - * Enable PTM only on interior devices (root ports, switch ports, - * etc.) on the assumption that it causes no link traffic until an - * endpoint enables it. - */ - if ((pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT || - pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END)) - return; - ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); if (!ptm) return; @@ -126,76 +120,76 @@ void pci_ptm_init(struct pci_dev *dev) pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_PTM, sizeof(u16)); pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap); - local_clock = (cap & PCI_PTM_GRANULARITY_MASK) >> 8; + dev->ptm_granularity = (cap & PCI_PTM_GRANULARITY_MASK) >> 8; /* - * There's no point in enabling PTM unless it's enabled in the - * upstream device or this device can be a PTM Root itself. Per - * the spec recommendation (PCIe r3.1, sec 7.32.3), select the - * furthest upstream Time Source as the PTM Root. + * Per the spec recommendation (PCIe r6.0, sec 7.9.15.3), select the + * furthest upstream Time Source as the PTM Root. For Endpoints, + * "the Effective Granularity is the maximum Local Clock Granularity + * reported by the PTM Root and all intervening PTM Time Sources." */ ups = pci_upstream_ptm(dev); - if (ups && ups->ptm_enabled) { - ctrl = PCI_PTM_CTRL_ENABLE; + if (ups) { if (ups->ptm_granularity == 0) dev->ptm_granularity = 0; - else if (ups->ptm_granularity > local_clock) + else if (ups->ptm_granularity > dev->ptm_granularity) dev->ptm_granularity = ups->ptm_granularity; - } else { - if (cap & PCI_PTM_CAP_ROOT) { - ctrl = PCI_PTM_CTRL_ENABLE | PCI_PTM_CTRL_ROOT; - dev->ptm_root = 1; - dev->ptm_granularity = local_clock; - } else - return; + } else if (cap & PCI_PTM_CAP_ROOT) { + dev->ptm_root = 1; + } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) { + + /* + * Per sec 7.9.15.3, this should be the Local Clock + * Granularity of the associated Time Source. But it + * doesn't say how to find that Time Source. + */ + dev->ptm_granularity = 0; } - ctrl |= dev->ptm_granularity << 8; - pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl); - dev->ptm_enabled = 1; - - pci_ptm_info(dev); + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT || + pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM) + pci_enable_ptm(dev, NULL); } +/** + * pci_enable_ptm() - Enable Precision Time Measurement + * @dev: PCI device + * @granularity: pointer to return granularity + * + * Enable Precision Time Measurement for @dev. If successful and + * @granularity is non-NULL, return the Effective Granularity. + * + * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or + * is not a PTM Root and lacks an upstream path of PTM-enabled devices. + */ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity) { - u16 ptm; - u32 cap, ctrl; + u16 ptm = dev->ptm_cap; struct pci_dev *ups; + u32 ctrl; - if (!pci_is_pcie(dev)) - return -EINVAL; - - ptm = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_PTM); if (!ptm) return -EINVAL; - dev->ptm_cap = ptm; - pci_read_config_dword(dev, ptm + PCI_PTM_CAP, &cap); - if (!(cap & PCI_PTM_CAP_REQ)) - return -EINVAL; - /* - * For a PCIe Endpoint, PTM is only useful if the endpoint can - * issue PTM requests to upstream devices that have PTM enabled. - * - * For Root Complex Integrated Endpoints, there is no upstream - * device, so there must be some implementation-specific way to - * associate the endpoint with a time source. + * A device uses local PTM Messages to request time information + * from a PTM Root that's farther upstream. Every device along the + * path must support PTM and have it enabled so it can handle the + * messages. Therefore, if this device is not a PTM Root, the + * upstream link partner must have PTM enabled before we can enable + * PTM. */ - if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) { + if (!dev->ptm_root) { ups = pci_upstream_ptm(dev); if (!ups || !ups->ptm_enabled) return -EINVAL; - - dev->ptm_granularity = ups->ptm_granularity; - } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) { - dev->ptm_granularity = 0; - } else - return -EINVAL; + } ctrl = PCI_PTM_CTRL_ENABLE; ctrl |= dev->ptm_granularity << 8; + if (dev->ptm_root) + ctrl |= PCI_PTM_CTRL_ROOT; + pci_write_config_dword(dev, ptm + PCI_PTM_CTRL, ctrl); dev->ptm_enabled = 1;