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Date: Mon, 11 Mar 2024 09:49:47 +0000
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Subject: [PATCH v5 2/2] usb: host: xhci-plat: add support for multi memory regions
From: Howard Yen <howardyen@google.com>
To: gregkh@linuxfoundation.org, rafael@kernel.org, mathias.nyman@intel.com, 
	hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, 
	andriy.shevchenko@linux.intel.com, petr.tesarik.ext@huawei.com, 
	broonie@kernel.org, james@equiv.tech, james.clark@arm.com, 
	masahiroy@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, 
	iommu@lists.linux.dev, Howard Yen <howardyen@google.com>
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The reason why it needs multiple regions is that in my system there is
an always-on subsystem which includes a small size memory, and several
functions need to run and occupy the memory from the small memory if
they need to run on the always-on subsystem. These functions must
allocate the memory from the small memory region, so that they can get
benefit from the always-on subsystem. So the small memory is split for
multiple functions which are satisfied with their generic use cases.
But in specific use cases, like USB3 devices which support the stream
trasnsfer or multiple devices connect to the host, they required more
memory than their pre-allocated memory region, so I tried to propose
this patch to give it the ability to get the memory from the other
larger memory to solve the issue.

Signed-off-by: Howard Yen <howardyen@google.com>
---
 drivers/usb/host/xhci-plat.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 3d071b875308..7892d3eb26d2 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -14,6 +14,7 @@
 #include <linux/pci.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/of_reserved_mem.h>
 #include <linux/platform_device.h>
 #include <linux/usb/phy.h>
 #include <linux/slab.h>
@@ -149,7 +150,7 @@ int xhci_plat_probe(struct platform_device *pdev, struct device *sysdev, const s
 	struct xhci_hcd		*xhci;
 	struct resource         *res;
 	struct usb_hcd		*hcd, *usb3_hcd;
-	int			ret;
+	int			i, count, ret;
 	int			irq;
 	struct xhci_plat_priv	*priv = NULL;
 	bool			of_match;
@@ -194,6 +195,19 @@ int xhci_plat_probe(struct platform_device *pdev, struct device *sysdev, const s
 
 	xhci->allow_single_roothub = 1;
 
+	count = of_property_count_u32_elems(sysdev->of_node, "memory-region");
+
+	for (i = 0; i < count; i++) {
+		ret = of_reserved_mem_device_init_by_idx(sysdev, sysdev->of_node, i);
+		if (ret) {
+			dev_err(sysdev, "Could not get reserved memory\n");
+			if (i > 0)
+				of_reserved_mem_device_release(sysdev);
+
+			return ret;
+		}
+	}
+
 	/*
 	 * Not all platforms have clks so it is not an error if the
 	 * clock do not exist.
@@ -431,6 +445,9 @@ void xhci_plat_remove(struct platform_device *dev)
 	clk_disable_unprepare(clk);
 	clk_disable_unprepare(reg_clk);
 	reset_control_assert(xhci->reset);
+
+	of_reserved_mem_device_release(hcd->self.sysdev);
+
 	usb_put_hcd(hcd);
 
 	pm_runtime_disable(&dev->dev);
-- 
2.44.0.278.ge034bb2e1d-goog