From patchwork Tue Apr 9 16:01:16 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Jiang X-Patchwork-Id: 13622913 X-Patchwork-Delegate: bhelgaas@google.com Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E5AD913AD3F; Tue, 9 Apr 2024 16:03:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712678582; cv=none; b=P2Y+2kJ/o67CrwfVMvbfO0ZKoN35JHofVhkVZZglfg75ZeuFKqJECgKl9wxJSAWq8TIyCwofBNDLEwiAsyFfJYMVk2wFgjUgWEmtKSi16MwDL0Xz25fwmGUCJXQ0cic0FTadjI5MPPEZqekpGh2YhsvM3WPXBjXjMbTvYmFN7ok= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712678582; c=relaxed/simple; bh=vvWR5zO14zGXLal37SMteyWzk17WOIVGlVgn28GuZqg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Nph6D53OsKO760BbH0Z9SMEv6MjWIqxBMxsTyPbXXB45+Tkwf87QI1KO3LOnCklScNCgGllu7THU4CaRDHe869gGfHbTY9YlCmPAfm1uIJQm/1ze1Veie6HWMI0EKdxKEiQCo2whgzFuq98yCvG/dYcoQ0kYnP1XLq0LroRu9lg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF130C433F1; Tue, 9 Apr 2024 16:03:02 +0000 (UTC) From: Dave Jiang To: linux-cxl@vger.kernel.org, linux-pci@vger.kernel.org Cc: dan.j.williams@intel.com, ira.weiny@intel.com, vishal.l.verma@intel.com, alison.schofield@intel.com, Jonathan.Cameron@huawei.com, dave@stgolabs.net, bhelgaas@google.com, lukas@wunner.de Subject: [PATCH v4 3/4] PCI: Create new reset method to force SBR for CXL Date: Tue, 9 Apr 2024 09:01:16 -0700 Message-ID: <20240409160256.94184-4-dave.jiang@intel.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240409160256.94184-1-dave.jiang@intel.com> References: <20240409160256.94184-1-dave.jiang@intel.com> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 CXL spec r3.1 8.1.5.2 By default Secondary Bus Reset (SBR) is masked for CXL ports. Introduce a new PCI reset method "cxl_bus" to force SBR on CXL ports by setting the unmask SBR bit in the CXL DVSEC port control register before performing the bus reset and restore the original value of the bit post reset. The new reset method allows the user to intentionally perform SBR on a CXL device without needing to set the "Unmask SBR" bit via a user tool. Reviewed-by: Jonathan Cameron Signed-off-by: Dave Jiang --- v4: - Use pci_dev_lock guard() on bridge. (Dan) --- drivers/pci/pci.c | 39 +++++++++++++++++++++++++++++++++++++++ include/linux/pci.h | 2 +- 2 files changed, 40 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 570b00fe10f7..3b4f7b369287 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4982,6 +4982,44 @@ static int pci_reset_bus_function(struct pci_dev *dev, bool probe) return pci_parent_bus_reset(dev, probe); } +static int cxl_reset_bus_function(struct pci_dev *dev, bool probe) +{ + struct pci_dev *bridge; + u16 dvsec, reg, val; + int rc; + + bridge = pci_upstream_bridge(dev); + if (!bridge) + return -ENOTTY; + + dvsec = cxl_port_dvsec(bridge); + if (!dvsec) + return -ENOTTY; + + if (probe) + return 0; + + guard(pci_dev)(bridge); + rc = pci_read_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL, ®); + if (rc) + return -ENOTTY; + + if (!(reg & PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR)) { + val = reg | PCI_DVSEC_CXL_PORT_CTL_UNMASK_SBR; + pci_write_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL, + val); + } else { + val = reg; + } + + rc = pci_reset_bus_function(dev, probe); + + if (reg != val) + pci_write_config_word(bridge, dvsec + PCI_DVSEC_CXL_PORT_CTL, reg); + + return rc; +} + void pci_dev_lock(struct pci_dev *dev) { /* block PM suspend, driver probe, etc. */ @@ -5066,6 +5104,7 @@ static const struct pci_reset_fn_method pci_reset_fn_methods[] = { { pci_af_flr, .name = "af_flr" }, { pci_pm_reset, .name = "pm" }, { pci_reset_bus_function, .name = "bus" }, + { cxl_reset_bus_function, .name = "cxl_bus" }, }; static ssize_t reset_method_show(struct device *dev, diff --git a/include/linux/pci.h b/include/linux/pci.h index 16493426a04f..235f37715a43 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -51,7 +51,7 @@ PCI_STATUS_PARITY) /* Number of reset methods used in pci_reset_fn_methods array in pci.c */ -#define PCI_NUM_RESET_METHODS 7 +#define PCI_NUM_RESET_METHODS 8 #define PCI_RESET_PROBE true #define PCI_RESET_DO_RESET false