PCI: endpoint: Add support for configurable page size

pci-epc-mem uses a page size equal to *PAGE_SIZE* (usually 4KB) to manage
the address space. However certain platforms like TI's K2G have a
restriction that this address space should be either divided into
1MB/2MB/4MB or 8MB sizes (Ref: 11.14.4.9.1 Outbound Address Translation in
K2G TRM SPRUHY8F January 2016 – Revised May 2017).  Add support to handle
different page sizes here.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/endpoint/pci-epc-mem.c

@@ -24,21 +24,54 @@
 #include <linux/pci-epc.h>
 
 /**
- * pci_epc_mem_init() - initialize the pci_epc_mem structure
+ * pci_epc_mem_get_order() - determine the allocation order of a memory size
+ * @mem: address space of the endpoint controller
+ * @size: the size for which to get the order
+ *
+ * Reimplement get_order() for mem->page_size since the generic get_order
+ * always gets order with a constant PAGE_SIZE.
+ */
+static int pci_epc_mem_get_order(struct pci_epc_mem *mem, size_t size)
+{
+	int order;
+	unsigned int page_shift = ilog2(mem->page_size);
+
+	size--;
+	size >>= page_shift;
+#if BITS_PER_LONG == 32
+	order = fls(size);
+#else
+	order = fls64(size);
+#endif
+	return order;
+}
+
+/**
+ * __pci_epc_mem_init() - initialize the pci_epc_mem structure
  * @epc: the EPC device that invoked pci_epc_mem_init
  * @phys_base: the physical address of the base
  * @size: the size of the address space
+ * @page_size: size of each page
  *
  * Invoke to initialize the pci_epc_mem structure used by the
  * endpoint functions to allocate mapped PCI address.
  */
-int pci_epc_mem_init(struct pci_epc *epc, phys_addr_t phys_base, size_t size)
+int __pci_epc_mem_init(struct pci_epc *epc, phys_addr_t phys_base, size_t size,
+		       size_t page_size)
 {
 	int ret;
 	struct pci_epc_mem *mem;
 	unsigned long *bitmap;
-	int pages = size >> PAGE_SHIFT;
-	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
+	unsigned int page_shift;
+	int pages;
+	int bitmap_size;
+
+	if (page_size < PAGE_SIZE)
+		page_size = PAGE_SIZE;
+
+	page_shift = ilog2(page_size);
+	pages = size >> page_shift;
+	bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
 
 	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 	if (!mem) {
@@ -54,6 +87,7 @@ int pci_epc_mem_init(struct pci_epc *epc, phys_addr_t phys_base, size_t size)
 
 	mem->bitmap = bitmap;
 	mem->phys_base = phys_base;
+	mem->page_size = page_size;
 	mem->pages = pages;
 	mem->size = size;
 
@@ -67,7 +101,7 @@ err_mem:
 err:
 return ret;
 }
-EXPORT_SYMBOL_GPL(pci_epc_mem_init);
+EXPORT_SYMBOL_GPL(__pci_epc_mem_init);
 
 /**
  * pci_epc_mem_exit() - cleanup the pci_epc_mem structure
@@ -101,13 +135,17 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
 	int pageno;
 	void __iomem *virt_addr;
 	struct pci_epc_mem *mem = epc->mem;
-	int order = get_order(size);
+	unsigned int page_shift = ilog2(mem->page_size);
+	int order;
+
+	size = ALIGN(size, mem->page_size);
+	order = pci_epc_mem_get_order(mem, size);
 
 	pageno = bitmap_find_free_region(mem->bitmap, mem->pages, order);
 	if (pageno < 0)
 		return NULL;
 
-	*phys_addr = mem->phys_base + (pageno << PAGE_SHIFT);
+	*phys_addr = mem->phys_base + (pageno << page_shift);
 	virt_addr = ioremap(*phys_addr, size);
 	if (!virt_addr)
 		bitmap_release_region(mem->bitmap, pageno, order);
@@ -129,11 +167,14 @@ void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
 			   void __iomem *virt_addr, size_t size)
 {
 	int pageno;
-	int order = get_order(size);
 	struct pci_epc_mem *mem = epc->mem;
+	unsigned int page_shift = ilog2(mem->page_size);
+	int order;
 
 	iounmap(virt_addr);
-	pageno = (phys_addr - mem->phys_base) >> PAGE_SHIFT;
+	pageno = (phys_addr - mem->phys_base) >> page_shift;
+	size = ALIGN(size, mem->page_size);
+	order = pci_epc_mem_get_order(mem, size);
 	bitmap_release_region(mem->bitmap, pageno, order);
 }
 EXPORT_SYMBOL_GPL(pci_epc_mem_free_addr);