USB: use genalloc for USB HCs with local memory

For HCs that have local memory, replace the current DMA API usage with
a genalloc generic allocator to manage the mappings for these devices.
To help users, introduce a new HCD API, usb_hcd_setup_local_mem() that
will setup up the genalloc backing up the device local memory. It will
be used in subsequent patches.  This is in preparation for dropping
the existing "coherent" dma mem declaration APIs.  The current
implementation was relying on a short circuit in the DMA API that in
the end, was acting as an allocator for these type of devices.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Tested-by: Fredrik Noring <noring@nocrew.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>

2 files changed, 45 insertions, 0 deletions

diff --git a/drivers/usb/core/buffer.c b/drivers/usb/core/buffer.c
index f641342cdec0..d2064ad7ad14 100644
--- a/drivers/usb/core/buffer.c
+++ b/drivers/usb/core/buffer.c
@@ -16,6 +16,7 @@
 #include <linux/io.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmapool.h>
+#include <linux/genalloc.h>
 #include <linux/usb.h>
 #include <linux/usb/hcd.h>
 
@@ -124,6 +125,9 @@ void *hcd_buffer_alloc(
 	if (size == 0)
 		return NULL;
 
+	if (hcd->localmem_pool)
+		return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
+
 	/* some USB hosts just use PIO */
 	if (!IS_ENABLED(CONFIG_HAS_DMA) ||
 	    (!is_device_dma_capable(bus->sysdev) &&
@@ -152,6 +156,11 @@ void hcd_buffer_free(
 	if (!addr)
 		return;
 
+	if (hcd->localmem_pool) {
+		gen_pool_free(hcd->localmem_pool, (unsigned long)addr, size);
+		return;
+	}
+
 	if (!IS_ENABLED(CONFIG_HAS_DMA) ||
 	    (!is_device_dma_capable(bus->sysdev) &&
 	     !(hcd->driver->flags & HCD_LOCAL_MEM))) {
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 94d22551fc1b..29b96e5e8621 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -29,6 +29,8 @@
 #include <linux/workqueue.h>
 #include <linux/pm_runtime.h>
 #include <linux/types.h>
+#include <linux/genalloc.h>
+#include <linux/io.h>
 
 #include <linux/phy/phy.h>
 #include <linux/usb.h>
@@ -3039,6 +3041,40 @@ usb_hcd_platform_shutdown(struct platform_device *dev)
 }
 EXPORT_SYMBOL_GPL(usb_hcd_platform_shutdown);
 
+int usb_hcd_setup_local_mem(struct usb_hcd *hcd, phys_addr_t phys_addr,
+			    dma_addr_t dma, size_t size)
+{
+	int err;
+	void *local_mem;
+
+	hcd->localmem_pool = devm_gen_pool_create(hcd->self.sysdev, PAGE_SHIFT,
+						  dev_to_node(hcd->self.sysdev),
+						  dev_name(hcd->self.sysdev));
+	if (IS_ERR(hcd->localmem_pool))
+		return PTR_ERR(hcd->localmem_pool);
+
+	local_mem = devm_memremap(hcd->self.sysdev, phys_addr,
+				  size, MEMREMAP_WC);
+	if (!local_mem)
+		return -ENOMEM;
+
+	/*
+	 * Here we pass a dma_addr_t but the arg type is a phys_addr_t.
+	 * It's not backed by system memory and thus there's no kernel mapping
+	 * for it.
+	 */
+	err = gen_pool_add_virt(hcd->localmem_pool, (unsigned long)local_mem,
+				dma, size, dev_to_node(hcd->self.sysdev));
+	if (err < 0) {
+		dev_err(hcd->self.sysdev, "gen_pool_add_virt failed with %d\n",
+			err);
+		return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_hcd_setup_local_mem);
+
 /*-------------------------------------------------------------------------*/
 
 #if IS_ENABLED(CONFIG_USB_MON)