linux-kernel - [PATCH 3/3] PCI/of fix of_dma_get_range; get PCI specific dma-ranges

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Date:   Wed,  3 May 2017 10:16:35 +0530
From:   Oza Pawandeep <oza.oza@...adcom.com>
To:     Joerg Roedel <joro@...tes.org>, Robin Murphy <robin.murphy@....com>
Cc:     iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
        Oza Pawandeep <oza.pawandeep@...il.com>,
        Oza Pawandeep <oza.oza@...adcom.com>
Subject: [PATCH 3/3] PCI/of fix of_dma_get_range; get PCI specific dma-ranges

current device framework and of framework integration assumes
dma-ranges in a way where memory-mapped devices define their
dma-ranges. (child-bus-address, parent-bus-address, length).

of_dma_configure is specifically written to take care of memory
mapped devices. but no implementation exists for pci to take
care of pcie based memory ranges.

for e.g. iproc based SOCs and other SOCs(suc as rcar) have PCI
world dma-ranges.
dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;

this patch fixes this patch fixes the bug in of_dma_get_range,
which with as is, parses the PCI memory ranges and return wrong
size as 0.

in order to get largest possible dma_mask. this patch also
retuns the largest possible size based on dma-ranges,

for e.g.
dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>;
we should get dev->coherent_dma_mask=0x7fffffffff.

based on which iova allocation space will honour PCI host
bridge limitations.

Bug: SOC-5216
Change-Id: I4c534bdd17e70c6b27327d39d1656e8ed0cf56d6
Signed-off-by: Oza Pawandeep <oza.oza@...adcom.com>
Reviewed-on: http://gerrit-ccxsw.broadcom.net/40762
Reviewed-by: vpx_checkpatch status <vpx_checkpatch@...adcom.com>
Reviewed-by: CCXSW <ccxswbuild@...adcom.com>
Reviewed-by: Scott Branden <scott.branden@...adcom.com>
Tested-by: vpx_autobuild status <vpx_autobuild@...adcom.com>
Tested-by: vpx_smoketest status <vpx_smoketest@...adcom.com>

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 02b2903..f7734fc 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -6,6 +6,7 @@
 #include <linux/ioport.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
+#include <linux/of_pci.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
 #include <linux/sizes.h>
@@ -830,6 +831,54 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
 	int ret = 0;
 	u64 dmaaddr;
 
+#ifdef CONFIG_PCI
+	struct resource_entry *window;
+	LIST_HEAD(res);
+
+	if (!node)
+		return -EINVAL;
+
+	if (of_bus_pci_match(np)) {
+		*size = 0;
+		/*
+		 * PCI dma-ranges is not mandatory property.
+		 * many devices do no need to have it, since
+		 * host bridge does not require inbound memory
+		 * configuration or rather have design limitations.
+		 * so we look for dma-ranges, if missing we
+		 * just return the caller full size, and also
+		 * no dma-ranges suggests that, host bridge allows
+		 * whatever comes in, so we set dma_addr to 0.
+		 */
+		ret = of_pci_get_dma_ranges(np, &res);
+		if (!ret) {
+			resource_list_for_each_entry(window, &res) {
+			struct resource *res_dma = window->res;
+
+			if (*size < resource_size(res_dma)) {
+				*dma_addr = res_dma->start - window->offset;
+				*paddr = res_dma->start;
+				*size = resource_size(res_dma);
+				}
+			}
+		}
+		pci_free_resource_list(&res);
+
+		/* ignore the empty ranges. */
+		if (*size == 0) {
+			pr_debug("empty/zero size dma-ranges found for node(%s)\n",
+				np->full_name);
+			*size = DMA_BIT_MASK(sizeof(dma_addr_t) * 8);
+			*dma_addr = *paddr = 0;
+			ret = 0;
+		}
+
+		pr_err("dma_addr(%llx) cpu_addr(%llx) size(%llx)\n",
+			 *dma_addr, *paddr, *size);
+		goto out;
+	}
+#endif
+
 	if (!node)
 		return -EINVAL;
 
-- 
1.9.1