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Thu, 06 Jun 2024 00:27:39 -0700 (PDT) Received: from [127.0.1.1] ([120.60.142.92]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-703fd494feasm566621b3a.100.2024.06.06.00.27.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Jun 2024 00:27:39 -0700 (PDT) From: Manivannan Sadhasivam Date: Thu, 06 Jun 2024 12:56:36 +0530 Subject: [PATCH 3/5] PCI: dwc: ep: Add a generic dw_pcie_ep_linkdown() API to handle Link Down event Precedence: bulk X-Mailing-List: linux-omap@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20240606-pci-deinit-v1-3-4395534520dc@linaro.org> References: <20240606-pci-deinit-v1-0-4395534520dc@linaro.org> In-Reply-To: <20240606-pci-deinit-v1-0-4395534520dc@linaro.org> To: Vignesh Raghavendra , Siddharth Vadapalli , Lorenzo Pieralisi , =?utf-8?q?Krzysztof_Wilczy?= =?utf-8?q?=C5=84ski?= , Rob Herring , Bjorn Helgaas , Richard Zhu , Lucas Stach , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Minghuan Lian , Mingkai Hu , Roy Zang , Jesper Nilsson , Jingoo Han , Srikanth Thokala , Marek Vasut , Yoshihiro Shimoda , Thierry Reding , Jonathan Hunter , Kunihiko Hayashi , Masami Hiramatsu , Kishon Vijay Abraham I Cc: linux-omap@vger.kernel.org, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@axis.com, linux-arm-msm@vger.kernel.org, linux-renesas-soc@vger.kernel.org, linux-tegra@vger.kernel.org, mhi@lists.linux.dev, Niklas Cassel , Manivannan Sadhasivam X-Mailer: b4 0.12.4 X-Developer-Signature: v=1; a=openpgp-sha256; l=6883; i=manivannan.sadhasivam@linaro.org; h=from:subject:message-id; bh=CyPVVcJODJ2tCBdthwAVOus+8aJwJCp9nbRVeHHFCiQ=; b=owEBbQGS/pANAwAKAVWfEeb+kc71AcsmYgBmYWTC1tIEUprHWLU3EJbohGb4dhy/c74Ocfx/L gFMNksZJ96JATMEAAEKAB0WIQRnpUMqgUjL2KRYJ5dVnxHm/pHO9QUCZmFkwgAKCRBVnxHm/pHO 9RqiB/wMM8Tt9y5MfBLY75mIEysw4v7tQX00FYGFLUMXPKf2oEKReZt+8J/fkmIfXEHWwiGONN2 uYmAwIdX2adk3LvRje/TCwo/ejcIJ2zykk0oss3oBr6t2GJXXIPuAKtNzISB4p2D3ey/Vjy/6xk 0Rtzznh3Wlz5rda3ypN/B5AEOGTLlzLQiqIYgn4iuPIgntiAE18mp0zhbiRpO4X/EwLyFSV7cwB X8XO5m6EKI1tkg6yVUJAsu4CJFSupVEEJbczhUSeXBVeFErpeyQeDM4ovmeHVXxvX+JHrTwPk+q eP90fxT0EFQCjKr/rr15hqsncrMBMRB74CQmXHyqxFRtrBCr X-Developer-Key: i=manivannan.sadhasivam@linaro.org; a=openpgp; fpr=C668AEC3C3188E4C611465E7488550E901166008 As per the PCIe base spec r5.0, section 5.2, Link Down event can happen under any of the following circumstances: 1. Fundamental/Hot reset 2. Link disable transmission by upstream component 3. Moving from L2/L3 to L0 In those cases, Link Down causes some non-sticky DWC registers to loose the state (like REBAR, etc...). So the drivers need to reinitialize them to function properly once the link comes back again. This is not a problem for drivers supporting PERST# IRQ, since they can reinitialize the registers in the PERST# IRQ callback. But for the drivers not supporting PERST#, there is no way they can reinitialize the registers other than relying on Link Down IRQ received when the link goes down. So let's add a DWC generic API dw_pcie_ep_linkdown() that reinitializes the non-sticky registers and also notifies the EPF drivers about link going down. This API can also be used by the drivers supporting PERST# to handle the scenario (2) mentioned above. NOTE: For the sake of code organization, move the dw_pcie_ep_linkup() definition just above dw_pcie_ep_linkdown(). Reviewed-by: Niklas Cassel Signed-off-by: Manivannan Sadhasivam --- drivers/pci/controller/dwc/pcie-designware-ep.c | 103 ++++++++++++++++-------- drivers/pci/controller/dwc/pcie-designware.h | 5 ++ 2 files changed, 73 insertions(+), 35 deletions(-) diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c index 78d5fc72c9cb..09ad6f7b5095 100644 --- a/drivers/pci/controller/dwc/pcie-designware-ep.c +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c @@ -15,18 +15,6 @@ #include #include -/** - * dw_pcie_ep_linkup - Notify EPF drivers about Link Up event - * @ep: DWC EP device - */ -void dw_pcie_ep_linkup(struct dw_pcie_ep *ep) -{ - struct pci_epc *epc = ep->epc; - - pci_epc_linkup(epc); -} -EXPORT_SYMBOL_GPL(dw_pcie_ep_linkup); - /** * dw_pcie_ep_get_func_from_ep - Get the struct dw_pcie_ep_func corresponding to * the endpoint function @@ -661,6 +649,34 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap) return 0; } +static void dw_pcie_ep_init_non_sticky_registers(struct dw_pcie *pci) +{ + unsigned int offset; + unsigned int nbars; + u32 reg, i; + + offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR); + + dw_pcie_dbi_ro_wr_en(pci); + + if (offset) { + reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL); + nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >> + PCI_REBAR_CTRL_NBAR_SHIFT; + + /* + * PCIe r6.0, sec 7.8.6.2 require us to support at least one + * size in the range from 1 MB to 512 GB. Advertise support + * for 1 MB BAR size only. + */ + for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL) + dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0); + } + + dw_pcie_setup(pci); + dw_pcie_dbi_ro_wr_dis(pci); +} + /** * dw_pcie_ep_init_registers - Initialize DWC EP specific registers * @ep: DWC EP device @@ -675,13 +691,11 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep) struct dw_pcie_ep_func *ep_func; struct device *dev = pci->dev; struct pci_epc *epc = ep->epc; - unsigned int offset, ptm_cap_base; - unsigned int nbars; + u32 ptm_cap_base, reg; u8 hdr_type; u8 func_no; - int i, ret; void *addr; - u32 reg; + int ret; hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) & PCI_HEADER_TYPE_MASK; @@ -744,25 +758,8 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep) if (ep->ops->init) ep->ops->init(ep); - offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR); ptm_cap_base = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_PTM); - dw_pcie_dbi_ro_wr_en(pci); - - if (offset) { - reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL); - nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >> - PCI_REBAR_CTRL_NBAR_SHIFT; - - /* - * PCIe r6.0, sec 7.8.6.2 require us to support at least one - * size in the range from 1 MB to 512 GB. Advertise support - * for 1 MB BAR size only. - */ - for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL) - dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, BIT(4)); - } - /* * PTM responder capability can be disabled only after disabling * PTM root capability. @@ -779,8 +776,7 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep) dw_pcie_dbi_ro_wr_dis(pci); } - dw_pcie_setup(pci); - dw_pcie_dbi_ro_wr_dis(pci); + dw_pcie_ep_init_non_sticky_registers(pci); return 0; @@ -791,6 +787,43 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep) } EXPORT_SYMBOL_GPL(dw_pcie_ep_init_registers); +/** + * dw_pcie_ep_linkup - Notify EPF drivers about Link Up event + * @ep: DWC EP device + */ +void dw_pcie_ep_linkup(struct dw_pcie_ep *ep) +{ + struct pci_epc *epc = ep->epc; + + pci_epc_linkup(epc); +} +EXPORT_SYMBOL_GPL(dw_pcie_ep_linkup); + +/** + * dw_pcie_ep_linkdown - Notify EPF drivers about Link Down event + * @ep: DWC EP device + * + * Non-sticky registers are also initialized before sending the notification to + * the EPF drivers. This is needed since the registers need to be initialized + * before the link comes back again. + */ +void dw_pcie_ep_linkdown(struct dw_pcie_ep *ep) +{ + struct dw_pcie *pci = to_dw_pcie_from_ep(ep); + struct pci_epc *epc = ep->epc; + + /* + * Initialize the non-sticky DWC registers as they would've reset post + * Link Down. This is specifically needed for drivers not supporting + * PERST# as they have no way to reinitialize the registers before the + * link comes back again. + */ + dw_pcie_ep_init_non_sticky_registers(pci); + + pci_epc_linkdown(epc); +} +EXPORT_SYMBOL_GPL(dw_pcie_ep_linkdown); + /** * dw_pcie_ep_init - Initialize the endpoint device * @ep: DWC EP device diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h index 49ae845a3662..89f9046af7eb 100644 --- a/drivers/pci/controller/dwc/pcie-designware.h +++ b/drivers/pci/controller/dwc/pcie-designware.h @@ -668,6 +668,7 @@ static inline void __iomem *dw_pcie_own_conf_map_bus(struct pci_bus *bus, #ifdef CONFIG_PCIE_DW_EP void dw_pcie_ep_linkup(struct dw_pcie_ep *ep); +void dw_pcie_ep_linkdown(struct dw_pcie_ep *ep); int dw_pcie_ep_init(struct dw_pcie_ep *ep); int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep); void dw_pcie_ep_deinit(struct dw_pcie_ep *ep); @@ -687,6 +688,10 @@ static inline void dw_pcie_ep_linkup(struct dw_pcie_ep *ep) { } +static inline void dw_pcie_ep_linkdown(struct dw_pcie_ep *ep) +{ +} + static inline int dw_pcie_ep_init(struct dw_pcie_ep *ep) { return 0;