usb: dma bounce buffer support V4
This patch adds dma bounce buffer support to the usb core. These buffers
can be enabled with the HCD_LOCAL_MEM flag, and they make sure that all data
passed to the host controller is allocated using dma_alloc_coherent().
Signed-off-by: Magnus Damm <***@igel.co.jp>
Acked-by: Alan Stern <***@rowland.harvard.edu>
Acked-by: David Brownell <***@users.sourceforge.net>
---
Only comment and checkpatch fixes since V3.
drivers/usb/core/buffer.c | 9 +-
drivers/usb/core/hcd.c | 176 +++++++++++++++++++++++++++++++++++++++------
drivers/usb/core/hcd.h | 1
3 files changed, 163 insertions(+), 23 deletions(-)
--- 0001/drivers/usb/core/buffer.c
+++ work/drivers/usb/core/buffer.c 2008-01-23 13:36:47.000000000 +0900
@@ -53,7 +53,8 @@ int hcd_buffer_create(struct usb_hcd *hc
char name[16];
int i, size;
- if (!hcd->self.controller->dma_mask)
+ if (!hcd->self.controller->dma_mask &&
+ !(hcd->driver->flags & HCD_LOCAL_MEM))
return 0;
for (i = 0; i < HCD_BUFFER_POOLS; i++) {
@@ -107,7 +108,8 @@ void *hcd_buffer_alloc(
int i;
/* some USB hosts just use PIO */
- if (!bus->controller->dma_mask) {
+ if (!bus->controller->dma_mask &&
+ !(hcd->driver->flags & HCD_LOCAL_MEM)) {
*dma = ~(dma_addr_t) 0;
return kmalloc(size, mem_flags);
}
@@ -132,7 +134,8 @@ void hcd_buffer_free(
if (!addr)
return;
- if (!bus->controller->dma_mask) {
+ if (!bus->controller->dma_mask &&
+ !(hcd->driver->flags & HCD_LOCAL_MEM)) {
kfree(addr);
return;
}
--- 0001/drivers/usb/core/hcd.c
+++ work/drivers/usb/core/hcd.c 2008-01-23 15:47:12.000000000 +0900
@@ -35,6 +35,7 @@
#include <linux/mutex.h>
#include <asm/irq.h>
#include <asm/byteorder.h>
+#include <asm/unaligned.h>
#include <linux/platform_device.h>
#include <linux/workqueue.h>
@@ -1112,48 +1113,177 @@ void usb_hcd_unlink_urb_from_ep(struct u
}
EXPORT_SYMBOL_GPL(usb_hcd_unlink_urb_from_ep);
-static void map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
+/*
+ * Some usb host controllers can only perform dma using a small SRAM area.
+ * The usb core itself is however optimized for host controllers that can dma
+ * using regular system memory - like pci devices doing bus mastering.
+ *
+ * To support host controllers with limited dma capabilites we provide dma
+ * bounce buffers. This feature can be enabled using the HCD_LOCAL_MEM flag.
+ * For this to work properly the host controller code must first use the
+ * function dma_declare_coherent_memory() to point out which memory area
+ * that should be used for dma allocations.
+ *
+ * The HCD_LOCAL_MEM flag then tells the usb code to allocate all data for
+ * dma using dma_alloc_coherent() which in turn allocates from the memory
+ * area pointed out with dma_declare_coherent_memory().
+ *
+ * So, to summarize...
+ *
+ * - We need "local" memory, canonical example being
+ * a small SRAM on a discrete controller being the
+ * only memory that the controller can read ...
+ * (a) "normal" kernel memory is no good, and
+ * (b) there's not enough to share
+ *
+ * - The only *portable* hook for such stuff in the
+ * DMA framework is dma_declare_coherent_memory()
+ *
+ * - So we use that, even though the primary requirement
+ * is that the memory be "local" (hence addressible
+ * by that device), not "coherent".
+ *
+ */
+
+static int hcd_alloc_coherent(struct usb_bus *bus,
+ gfp_t mem_flags, dma_addr_t *dma_handle,
+ void **vaddr_handle, size_t size,
+ enum dma_data_direction dir)
+{
+ unsigned char *vaddr;
+
+ vaddr = hcd_buffer_alloc(bus, size + sizeof(vaddr),
+ mem_flags, dma_handle);
+ if (!vaddr)
+ return -ENOMEM;
+
+ /*
+ * Store the virtual address of the buffer at the end
+ * of the allocated dma buffer. The size of the buffer
+ * may be uneven so use unaligned functions instead
+ * of just rounding up. It makes sense to optimize for
+ * memory footprint over access speed since the amount
+ * of memory available for dma may be limited.
+ */
+ put_unaligned((unsigned long)*vaddr_handle,
+ (unsigned long *)(vaddr + size));
+
+ if (dir == DMA_TO_DEVICE)
+ memcpy(vaddr, *vaddr_handle, size);
+
+ *vaddr_handle = vaddr;
+ return 0;
+}
+
+static void hcd_free_coherent(struct usb_bus *bus, dma_addr_t *dma_handle,
+ void **vaddr_handle, size_t size,
+ enum dma_data_direction dir)
+{
+ unsigned char *vaddr = *vaddr_handle;
+
+ vaddr = (void *)get_unaligned((unsigned long *)(vaddr + size));
+
+ if (dir == DMA_FROM_DEVICE)
+ memcpy(vaddr, *vaddr_handle, size);
+
+ hcd_buffer_free(bus, size + sizeof(vaddr), *vaddr_handle, *dma_handle);
+
+ *vaddr_handle = vaddr;
+ *dma_handle = 0;
+}
+
+static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
+ gfp_t mem_flags)
{
+ enum dma_data_direction dir;
+ int ret = 0;
+
/* Map the URB's buffers for DMA access.
* Lower level HCD code should use *_dma exclusively,
* unless it uses pio or talks to another transport.
*/
- if (hcd->self.uses_dma && !is_root_hub(urb->dev)) {
- if (usb_endpoint_xfer_control(&urb->ep->desc)
- && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
- urb->setup_dma = dma_map_single (
+ if (is_root_hub(urb->dev))
+ return 0;
+
+ if (usb_endpoint_xfer_control(&urb->ep->desc)
+ && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP)) {
+ if (hcd->self.uses_dma)
+ urb->setup_dma = dma_map_single(
hcd->self.controller,
urb->setup_packet,
- sizeof (struct usb_ctrlrequest),
+ sizeof(struct usb_ctrlrequest),
DMA_TO_DEVICE);
- if (urb->transfer_buffer_length != 0
- && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
+ else if (hcd->driver->flags & HCD_LOCAL_MEM)
+ ret = hcd_alloc_coherent(
+ urb->dev->bus, mem_flags,
+ &urb->setup_dma,
+ (void **)&urb->setup_packet,
+ sizeof(struct usb_ctrlrequest),
+ DMA_TO_DEVICE);
+ }
+
+ dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+ if (ret == 0 && urb->transfer_buffer_length != 0
+ && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
+ if (hcd->self.uses_dma)
urb->transfer_dma = dma_map_single (
hcd->self.controller,
urb->transfer_buffer,
urb->transfer_buffer_length,
- usb_urb_dir_in(urb)
- ? DMA_FROM_DEVICE
- : DMA_TO_DEVICE);
+ dir);
+ else if (hcd->driver->flags & HCD_LOCAL_MEM) {
+ ret = hcd_alloc_coherent(
+ urb->dev->bus, mem_flags,
+ &urb->transfer_dma,
+ &urb->transfer_buffer,
+ urb->transfer_buffer_length,
+ dir);
+
+ if (ret && usb_endpoint_xfer_control(&urb->ep->desc)
+ && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
+ hcd_free_coherent(urb->dev->bus,
+ &urb->setup_dma,
+ (void **)&urb->setup_packet,
+ sizeof(struct usb_ctrlrequest),
+ DMA_TO_DEVICE);
+ }
}
+ return ret;
}
static void unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
{
- if (hcd->self.uses_dma && !is_root_hub(urb->dev)) {
- if (usb_endpoint_xfer_control(&urb->ep->desc)
- && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
+ enum dma_data_direction dir;
+
+ if (is_root_hub(urb->dev))
+ return;
+
+ if (usb_endpoint_xfer_control(&urb->ep->desc)
+ && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP)) {
+ if (hcd->self.uses_dma)
dma_unmap_single(hcd->self.controller, urb->setup_dma,
sizeof(struct usb_ctrlrequest),
DMA_TO_DEVICE);
- if (urb->transfer_buffer_length != 0
- && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
+ else if (hcd->driver->flags & HCD_LOCAL_MEM)
+ hcd_free_coherent(urb->dev->bus, &urb->setup_dma,
+ (void **)&urb->setup_packet,
+ sizeof(struct usb_ctrlrequest),
+ DMA_TO_DEVICE);
+ }
+
+ dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+ if (urb->transfer_buffer_length != 0
+ && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
+ if (hcd->self.uses_dma)
dma_unmap_single(hcd->self.controller,
urb->transfer_dma,
urb->transfer_buffer_length,
- usb_urb_dir_in(urb)
- ? DMA_FROM_DEVICE
- : DMA_TO_DEVICE);
+ dir);
+ else if (hcd->driver->flags & HCD_LOCAL_MEM)
+ hcd_free_coherent(urb->dev->bus, &urb->transfer_dma,
+ &urb->transfer_buffer,
+ urb->transfer_buffer_length,
+ dir);
}
}
@@ -1185,7 +1315,12 @@ int usb_hcd_submit_urb (struct urb *urb,
* URBs must be submitted in process context with interrupts
* enabled.
*/
- map_urb_for_dma(hcd, urb);
+ status = map_urb_for_dma(hcd, urb, mem_flags);
+ if (unlikely(status)) {
+ usbmon_urb_submit_error(&hcd->self, urb, status);
+ goto error;
+ }
+
if (is_root_hub(urb->dev))
status = rh_urb_enqueue(hcd, urb);
else
@@ -1194,6 +1329,7 @@ int usb_hcd_submit_urb (struct urb *urb,
if (unlikely(status)) {
usbmon_urb_submit_error(&hcd->self, urb, status);
unmap_urb_for_dma(hcd, urb);
+ error:
urb->hcpriv = NULL;
INIT_LIST_HEAD(&urb->urb_list);
atomic_dec(&urb->use_count);
--- 0001/drivers/usb/core/hcd.h
+++ work/drivers/usb/core/hcd.h 2008-01-23 15:43:58.000000000 +0900
@@ -165,6 +165,7 @@ struct hc_driver {
int flags;
#define HCD_MEMORY 0x0001 /* HC regs use memory (else I/O) */
+#define HCD_LOCAL_MEM 0x0002 /* HC needs local memory */
#define HCD_USB11 0x0010 /* USB 1.1 */
#define HCD_USB2 0x0020 /* USB 2.0 */
-
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