PCI: epf-mhi: Make use of the alignment restriction from EPF core

Instead of hardcoding the alignment restriction in the EPF_MHI driver, make
use of the info available from the EPF core that reflects the alignment
restriction of the endpoint controller.

For this purpose, let's introduce the get_align_offset() static function.

[kwilczynski: update get_align_offset() to avoid issues on 32-bit architectures]
Link: https://lore.kernel.org/linux-pci/20230717065459.14138-3-manivannan.sadhasivam@linaro.org
Link: https://lore.kernel.org/linux-pci/20230826150626.23309-1-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>

Author: Mani-Sadhasivam

drivers/pci/endpoint/functions/pci-epf-mhi.c

@@ -92,6 +92,7 @@ static const struct pci_epf_mhi_ep_info sdx55_info = {
 };
 
 struct pci_epf_mhi {
+	const struct pci_epc_features *epc_features;
 	const struct pci_epf_mhi_ep_info *info;
 	struct mhi_ep_cntrl mhi_cntrl;
 	struct pci_epf *epf;
@@ -102,6 +103,11 @@ struct pci_epf_mhi {
 	int irq;
 };
 
+static size_t get_align_offset(struct pci_epf_mhi *epf_mhi, u64 addr)
+{
+	return addr & (epf_mhi->epc_features->align -1);
+}
+
 static int __pci_epf_mhi_alloc_map(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
 				 phys_addr_t *paddr, void __iomem **vaddr,
 				 size_t offset, size_t size)
@@ -133,8 +139,7 @@ static int pci_epf_mhi_alloc_map(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
 				 size_t size)
 {
 	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
-	struct pci_epc *epc = epf_mhi->epf->epc;
-	size_t offset = pci_addr & (epc->mem->window.page_size - 1);
+	size_t offset = get_align_offset(epf_mhi, pci_addr);
 
 	return __pci_epf_mhi_alloc_map(mhi_cntrl, pci_addr, paddr, vaddr,
 				      offset, size);
@@ -159,9 +164,7 @@ static void pci_epf_mhi_unmap_free(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
 				   size_t size)
 {
 	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
-	struct pci_epf *epf = epf_mhi->epf;
-	struct pci_epc *epc = epf->epc;
-	size_t offset = pci_addr & (epc->mem->window.page_size - 1);
+	size_t offset = get_align_offset(epf_mhi, pci_addr);
 
 	__pci_epf_mhi_unmap_free(mhi_cntrl, pci_addr, paddr, vaddr, offset,
 				 size);
@@ -185,7 +188,7 @@ static int pci_epf_mhi_read_from_host(struct mhi_ep_cntrl *mhi_cntrl, u64 from,
 				      void *to, size_t size)
 {
 	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
-	size_t offset = from % SZ_4K;
+	size_t offset = get_align_offset(epf_mhi, from);
 	void __iomem *tre_buf;
 	phys_addr_t tre_phys;
 	int ret;
@@ -213,7 +216,7 @@ static int pci_epf_mhi_write_to_host(struct mhi_ep_cntrl *mhi_cntrl,
 				     void *from, u64 to, size_t size)
 {
 	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
-	size_t offset = to % SZ_4K;
+	size_t offset = get_align_offset(epf_mhi, to);
 	void __iomem *tre_buf;
 	phys_addr_t tre_phys;
 	int ret;
@@ -270,6 +273,10 @@ static int pci_epf_mhi_core_init(struct pci_epf *epf)
 		return ret;
 	}
 
+	epf_mhi->epc_features = pci_epc_get_features(epc, epf->func_no, epf->vfunc_no);
+	if (!epf_mhi->epc_features)
+		return -ENODATA;
+
 	return 0;
 }