linux-kernel - [PATCH v4 2/2] PCI: iproc: Add outbound configuration for 32-bit I/O region

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Date:   Fri,  1 Mar 2019 10:22:16 +0530
From:   Srinath Mannam <srinath.mannam@...adcom.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>
Cc:     bcm-kernel-feedback-list@...adcom.com, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Srinath Mannam <srinath.mannam@...adcom.com>,
        Abhishek Shah <abhishek.shah@...adcom.com>,
        Ray Jui <ray.jui@...adcom.com>
Subject: [PATCH v4 2/2] PCI: iproc: Add outbound configuration for 32-bit I/O region

In the present driver outbound window configuration is done to map above
32-bit address I/O regions with corresponding PCI memory range given in
ranges DT property.

This patch add outbound window configuration to map below 32-bit I/O range
with corresponding PCI memory, which helps to access I/O region in ARM
32-bit and one to one mapping of I/O region to PCI memory.

Ex:
1. ranges DT property given for current driver is,
    ranges = <0x83000000 0x0 0x40000000 0x4 0x00000000 0 0x40000000>;
    I/O region address is 0x400000000
2. ranges DT property can be given after this patch,
    ranges = <0x83000000 0x0 0x42000000 0x0 0x42000000 0 0x2000000>;
    I/O region address is 0x42000000

Signed-off-by: Srinath Mannam <srinath.mannam@...adcom.com>
Signed-off-by: Abhishek Shah <abhishek.shah@...adcom.com>
Signed-off-by: Ray Jui <ray.jui@...adcom.com>
---
 drivers/pci/controller/pcie-iproc.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
index b882255..080f142 100644
--- a/drivers/pci/controller/pcie-iproc.c
+++ b/drivers/pci/controller/pcie-iproc.c
@@ -955,8 +955,25 @@ static int iproc_pcie_setup_ob(struct iproc_pcie *pcie, u64 axi_addr,
 			resource_size_t window_size =
 				ob_map->window_sizes[size_idx] * SZ_1M;
 
-			if (size < window_size)
-				continue;
+			/*
+			 * Keep iterating until we reach the last window and
+			 * with the minimal window size at index zero. In this
+			 * case, we take a compromise by mapping it using the
+			 * minimum window size that can be supported
+			 */
+			if (size < window_size) {
+				if (size_idx > 0 || window_idx > 0)
+					continue;
+
+				/*
+				 * For the corner case of reaching the minimal
+				 * window size that can be supported on the
+				 * last window
+				 */
+				axi_addr = ALIGN_DOWN(axi_addr, window_size);
+				pci_addr = ALIGN_DOWN(pci_addr, window_size);
+				size = window_size;
+			}
 
 			if (!IS_ALIGNED(axi_addr, window_size) ||
 			    !IS_ALIGNED(pci_addr, window_size)) {
-- 
2.7.4