linux-kernel - [PATCH v8 3/6] PCI: endpoint: Add pci_epf_align

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Message-Id: <20241116-ep-msi-v8-3-6f1f68ffd1bb@nxp.com>
Date: Sat, 16 Nov 2024 09:40:43 -0500
From: Frank Li <Frank.Li@....com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>, 
 Krzysztof Wilczyński <kw@...ux.com>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Bjorn Helgaas <bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, 
 imx@...ts.linux.dev, Niklas Cassel <cassel@...nel.org>, dlemoal@...nel.org, 
 maz@...nel.org, tglx@...utronix.de, jdmason@...zu.us, 
 Frank Li <Frank.Li@....com>
Subject: [PATCH v8 3/6] PCI: endpoint: Add pci_epf_align_addr() helper for
 address alignment

Introduce the helper function pci_epf_align_addr() to adjust addresses
according to PCI BAR alignment requirements, converting addresses into base
and offset values.

Signed-off-by: Frank Li <Frank.Li@....com>
---
change from v7 to v8
- change name to pci_epf_align_inbound_addr()
- update comment said only need for memory, which not allocated by
pci_epf_alloc_space().

change from v6 to v7
- new patch
---
 drivers/pci/endpoint/pci-epf-core.c | 45 +++++++++++++++++++++++++++++++++++++
 include/linux/pci-epf.h             | 14 ++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
index 8fa2797d4169a..4dfc218ebe20b 100644
--- a/drivers/pci/endpoint/pci-epf-core.c
+++ b/drivers/pci/endpoint/pci-epf-core.c
@@ -464,6 +464,51 @@ struct pci_epf *pci_epf_create(const char *name)
 }
 EXPORT_SYMBOL_GPL(pci_epf_create);
 
+/**
+ * pci_epf_align_inbound_addr() - Get base address and offset that match bar's
+ *			  alignment requirement
+ * @epf: the EPF device
+ * @addr: the address of the memory
+ * @bar: the BAR number corresponding to map addr
+ * @base: return base address, which match BAR's alignment requirement, nothing
+ *	  return if NULL
+ * @off: return offset, nothing return if NULL
+ *
+ * Helper function to convert input 'addr' to base and offset, which match
+ * BAR's alignment requirement.
+ *
+ * The pci_epf_alloc_space() function already accounts for alignment. This is
+ * primarily intended for use with other memory regions not allocated by
+ * pci_epf_alloc_space(), such as peripheral register spaces or the trigger
+ * address for a platform MSI controller.
+ */
+int pci_epf_align_inbound_addr(struct pci_epf *epf, enum pci_barno bar,
+			       u64 addr, u64 *base, size_t *off)
+{
+	const struct pci_epc_features *epc_features;
+	u64 align;
+
+	epc_features = pci_epc_get_features(epf->epc, epf->func_no, epf->vfunc_no);
+	if (!epc_features) {
+		dev_err(&epf->dev, "epc_features not implemented\n");
+		return -EOPNOTSUPP;
+	}
+
+	align = epc_features->align;
+	align = align ? align : 128;
+	if (epc_features->bar[bar].type == BAR_FIXED)
+		align = max(epc_features->bar[bar].fixed_size, align);
+
+	if (base)
+		*base = round_down(addr, align);
+
+	if (off)
+		*off = addr & (align - 1);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pci_epf_align_inbound_addr);
+
 static void pci_epf_dev_release(struct device *dev)
 {
 	struct pci_epf *epf = to_pci_epf(dev);
diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
index 5374e6515ffa0..eff73ccb5e702 100644
--- a/include/linux/pci-epf.h
+++ b/include/linux/pci-epf.h
@@ -238,6 +238,20 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar,
 			  enum pci_epc_interface_type type);
 void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar,
 			enum pci_epc_interface_type type);
+
+int pci_epf_align_inbound_addr(struct pci_epf *epf, enum pci_barno bar,
+			       u64 addr, u64 *base, size_t *off);
+static inline int pci_epf_align_inbound_addr_lo_hi(struct pci_epf *epf, enum pci_barno bar,
+						   u32 low, u32 high, u64 *base, size_t *off)
+{
+	u64 addr = high;
+
+	addr <<= 32;
+	addr |= low;
+
+	return pci_epf_align_inbound_addr(epf, bar, addr, base, off);
+}
+
 int pci_epf_bind(struct pci_epf *epf);
 void pci_epf_unbind(struct pci_epf *epf);
 int pci_epf_add_vepf(struct pci_epf *epf_pf, struct pci_epf *epf_vf);

-- 
2.34.1