USB: net2280: update dma buffer allocation

This updates the code handling dma-coherent buffer allocations, basically
reusing code from the musb_hdrc driver.  Instead of trying to work around two
significant limitations of the dma framework (memory wastage for buffers
smaller than a page, and inconsistency between calling context requirements
for allocation and free) this just works around one of them (the latter).

So count this as two steps forward (bugfixes:  the latter issue could cause
errors on some platforms, and some MIPS changes broke code for the former), 
and one step back (increasing cross-platform memory wastage).

Plus linelength and whitespace fixes; and minor data segment shrinkage.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 88 insertions, 68 deletions

diff --git a/drivers/usb/gadget/net2280.c b/drivers/usb/gadget/net2280.c
index 09243239d948..3bda37f9a35f 100644
--- a/drivers/usb/gadget/net2280.c
+++ b/drivers/usb/gadget/net2280.c
@@ -2,7 +2,7 @@
  * Driver for the PLX NET2280 USB device controller.
  * Specs and errata are available from <http://www.plxtech.com>.
  *
- * PLX Technology Inc. (formerly NetChip Technology) supported the 
+ * PLX Technology Inc. (formerly NetChip Technology) supported the
  * development of this driver.
  *
  *
@@ -26,7 +26,8 @@
  * Copyright (C) 2003 David Brownell
  * Copyright (C) 2003-2005 PLX Technology, Inc.
  *
- * Modified Seth Levy 2005 PLX Technology, Inc. to provide compatibility with 2282 chip
+ * Modified Seth Levy 2005 PLX Technology, Inc. to provide compatibility
+ *      with 2282 chip
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -85,7 +86,7 @@ static const char driver_name [] = "net2280";
 static const char driver_desc [] = DRIVER_DESC;
 
 static const char ep0name [] = "ep0";
-static const char *ep_name [] = {
+static const char *const ep_name [] = {
         ep0name,
         "ep-a", "ep-b", "ep-c", "ep-d",
         "ep-e", "ep-f",
@@ -225,7 +226,9 @@ net2280_enable (struct usb_ep *_ep, const struct usb_endpoint_descriptor *desc)
         if (!ep->is_in)
                 writel ((1 << SET_NAK_OUT_PACKETS), &ep->regs->ep_rsp);
         else if (dev->pdev->device != 0x2280) {
-                /* Added for 2282, Don't use nak packets on an in endpoint, this was ignored on 2280 */
+                /* Added for 2282, Don't use nak packets on an in endpoint,
+                 * this was ignored on 2280
+                 */
                 writel ((1 << CLEAR_NAK_OUT_PACKETS)
                         | (1 << CLEAR_NAK_OUT_PACKETS_MODE), &ep->regs->ep_rsp);
         }
@@ -288,7 +291,7 @@ static int handshake (u32 __iomem *ptr, u32 mask, u32 done, int usec)
         return -ETIMEDOUT;
 }
 
-static struct usb_ep_ops net2280_ep_ops;
+static const struct usb_ep_ops net2280_ep_ops;
 
 static void ep_reset (struct net2280_regs __iomem *regs, struct net2280_ep *ep)
 {
@@ -449,34 +452,15 @@ net2280_free_request (struct usb_ep *_ep, struct usb_request *_req)
 
 /*-------------------------------------------------------------------------*/
 
-#undef USE_KMALLOC
-
-/* many common platforms have dma-coherent caches, which means that it's
- * safe to use kmalloc() memory for all i/o buffers without using any
- * cache flushing calls.  (unless you're trying to share cache lines
- * between dma and non-dma activities, which is a slow idea in any case.)
+/*
+ * dma-coherent memory allocation (for dma-capable endpoints)
  *
- * other platforms need more care, with 2.5 having a moderately general
- * solution (which falls down for allocations smaller than one page)
- * that improves significantly on the 2.4 PCI allocators by removing
- * the restriction that memory never be freed in_interrupt().
+ * NOTE: the dma_*_coherent() API calls suck.  Most implementations are
+ * (a) page-oriented, so small buffers lose big; and (b) asymmetric with
+ * respect to calls with irqs disabled:  alloc is safe, free is not.
+ * We currently work around (b), but not (a).
  */
-#if     defined(CONFIG_X86)
-#define USE_KMALLOC
-
-#elif   defined(CONFIG_PPC) && !defined(CONFIG_NOT_COHERENT_CACHE)
-#define USE_KMALLOC
 
-#elif   defined(CONFIG_MIPS) && !defined(CONFIG_DMA_NONCOHERENT)
-#define USE_KMALLOC
-
-/* FIXME there are other cases, including an x86-64 one ...  */
-#endif
-
-/* allocating buffers this way eliminates dma mapping overhead, which
- * on some platforms will mean eliminating a per-io buffer copy.  with
- * some kinds of system caches, further tweaks may still be needed.
- */
 static void *
 net2280_alloc_buffer (
         struct usb_ep           *_ep,
@@ -493,43 +477,71 @@ net2280_alloc_buffer (
                 return NULL;
         *dma = DMA_ADDR_INVALID;
 
-#if     defined(USE_KMALLOC)
-        retval = kmalloc(bytes, gfp_flags);
-        if (retval)
-                *dma = virt_to_phys(retval);
-#else
-        if (ep->dma) {
-                /* the main problem with this call is that it wastes memory
-                 * on typical 1/N page allocations: it allocates 1-N pages.
-                 */
-#warning Using dma_alloc_coherent even with buffers smaller than a page.
+        if (ep->dma)
                 retval = dma_alloc_coherent(&ep->dev->pdev->dev,
                                 bytes, dma, gfp_flags);
-        } else
+        else
                 retval = kmalloc(bytes, gfp_flags);
-#endif
         return retval;
 }
 
+static DEFINE_SPINLOCK(buflock);
+static LIST_HEAD(buffers);
+
+struct free_record {
+        struct list_head        list;
+        struct device           *dev;
+        unsigned                bytes;
+        dma_addr_t              dma;
+};
+
+static void do_free(unsigned long ignored)
+{
+        spin_lock_irq(&buflock);
+        while (!list_empty(&buffers)) {
+                struct free_record      *buf;
+
+                buf = list_entry(buffers.next, struct free_record, list);
+                list_del(&buf->list);
+                spin_unlock_irq(&buflock);
+
+                dma_free_coherent(buf->dev, buf->bytes, buf, buf->dma);
+
+                spin_lock_irq(&buflock);
+        }
+        spin_unlock_irq(&buflock);
+}
+
+static DECLARE_TASKLET(deferred_free, do_free, 0);
+
 static void
 net2280_free_buffer (
         struct usb_ep *_ep,
-        void *buf,
+        void *address,
         dma_addr_t dma,
         unsigned bytes
 ) {
         /* free memory into the right allocator */
-#ifndef USE_KMALLOC
         if (dma != DMA_ADDR_INVALID) {
                 struct net2280_ep       *ep;
+                struct free_record      *buf = address;
+                unsigned long           flags;
 
                 ep = container_of(_ep, struct net2280_ep, ep);
                 if (!_ep)
                         return;
-                dma_free_coherent(&ep->dev->pdev->dev, bytes, buf, dma);
+
+                ep = container_of (_ep, struct net2280_ep, ep);
+                buf->dev = &ep->dev->pdev->dev;
+                buf->bytes = bytes;
+                buf->dma = dma;
+
+                spin_lock_irqsave(&buflock, flags);
+                list_add_tail(&buf->list, &buffers);
+                tasklet_schedule(&deferred_free);
+                spin_unlock_irqrestore(&buflock, flags);
         } else
-#endif
-                kfree (buf);
+                kfree (address);
 }
 
 /*-------------------------------------------------------------------------*/
@@ -737,7 +749,8 @@ fill_dma_desc (struct net2280_ep *ep, struct net2280_request *req, int valid)
          */
         if (ep->is_in)
                 dmacount |= (1 << DMA_DIRECTION);
-        if ((!ep->is_in && (dmacount % ep->ep.maxpacket) != 0) || ep->dev->pdev->device != 0x2280)
+        if ((!ep->is_in && (dmacount % ep->ep.maxpacket) != 0)
+                        || ep->dev->pdev->device != 0x2280)
                 dmacount |= (1 << END_OF_CHAIN);
 
         req->valid = valid;
@@ -812,7 +825,7 @@ static void start_dma (struct net2280_ep *ep, struct net2280_request *req)
 
         /* previous OUT packet might have been short */
         if (!ep->is_in && ((tmp = readl (&ep->regs->ep_stat))
-                                & (1 << NAK_OUT_PACKETS)) != 0) {
+                                & (1 << NAK_OUT_PACKETS)) != 0) {
                 writel ((1 << SHORT_PACKET_TRANSFERRED_INTERRUPT),
                         &ep->regs->ep_stat);
 
@@ -1373,7 +1386,7 @@ net2280_fifo_flush (struct usb_ep *_ep)
         (void) readl (&ep->regs->ep_rsp);
 }
 
-static struct usb_ep_ops net2280_ep_ops = {
+static const struct usb_ep_ops net2280_ep_ops = {
         .enable         = net2280_enable,
         .disable        = net2280_disable,
 
@@ -1631,7 +1644,7 @@ show_registers (struct device *_dev, struct device_attribute *attr, char *buf)
         }
 
         /* Indexed Registers */
-                // none yet 
+                // none yet
 
         /* Statistics */
         t = scnprintf (next, size, "\nirqs:  ");
@@ -1691,11 +1704,11 @@ show_queues (struct device *_dev, struct device_attribute *attr, char *buf)
                                 ({ char *val;
                                  switch (d->bmAttributes & 0x03) {
                                  case USB_ENDPOINT_XFER_BULK:
-                                        val = "bulk"; break;
+                                        val = "bulk"; break;
                                  case USB_ENDPOINT_XFER_INT:
-                                        val = "intr"; break;
+                                        val = "intr"; break;
                                  default:
-                                        val = "iso"; break;
+                                        val = "iso"; break;
                                  }; val; }),
                                 le16_to_cpu (d->wMaxPacketSize) & 0x1fff,
                                 ep->dma ? "dma" : "pio", ep->fifo_size
@@ -1808,8 +1821,8 @@ extern int net2280_set_fifo_mode (struct usb_gadget *gadget, int mode);
  * net2280_set_fifo_mode - change allocation of fifo buffers
  * @gadget: access to the net2280 device that will be updated
  * @mode: 0 for default, four 1kB buffers (ep-a through ep-d);
- *      1 for two 2kB buffers (ep-a and ep-b only);
- *      2 for one 2kB buffer (ep-a) and two 1kB ones (ep-b, ep-c).
+ *      1 for two 2kB buffers (ep-a and ep-b only);
+ *      2 for one 2kB buffer (ep-a) and two 1kB ones (ep-b, ep-c).
  *
  * returns zero on success, else negative errno.  when this succeeds,
  * the contents of gadget->ep_list may have changed.
@@ -2241,7 +2254,8 @@ static void handle_ep_small (struct net2280_ep *ep)
                                 req->td->dmacount = 0;
                                 t = readl (&ep->regs->ep_avail);
                                 dma_done (ep, req, count,
-                                        (ep->out_overflow || t) ? -EOVERFLOW : 0);
+                                        (ep->out_overflow || t)
+                                                ? -EOVERFLOW : 0);
                         }
 
                         /* also flush to prevent erratum 0106 trouble */
@@ -2411,7 +2425,7 @@ static void handle_stat0_irqs (struct net2280 *dev, u32 stat)
                         , &ep->regs->ep_stat);
                 u.raw [0] = readl (&dev->usb->setup0123);
                 u.raw [1] = readl (&dev->usb->setup4567);
-                
+
                 cpu_to_le32s (&u.raw [0]);
                 cpu_to_le32s (&u.raw [1]);
 
@@ -2578,14 +2592,16 @@ static void handle_stat1_irqs (struct net2280 *dev, u32 stat)
 
         /* VBUS disconnect is indicated by VBUS_PIN and VBUS_INTERRUPT set.
          * Root Port Reset is indicated by ROOT_PORT_RESET_INTERRRUPT set and
-         * both HIGH_SPEED and FULL_SPEED clear (as ROOT_PORT_RESET_INTERRUPT 
+         * both HIGH_SPEED and FULL_SPEED clear (as ROOT_PORT_RESET_INTERRUPT
          * only indicates a change in the reset state).
          */
         if (stat & tmp) {
                 writel (tmp, &dev->regs->irqstat1);
-                if ((((stat & (1 << ROOT_PORT_RESET_INTERRUPT)) && 
-                                ((readl (&dev->usb->usbstat) & mask) == 0))
-                                || ((readl (&dev->usb->usbctl) & (1 << VBUS_PIN)) == 0) 
+                if ((((stat & (1 << ROOT_PORT_RESET_INTERRUPT))
+                                        && ((readl (&dev->usb->usbstat) & mask)
+                                                        == 0))
+                                || ((readl (&dev->usb->usbctl)
+                                        & (1 << VBUS_PIN)) == 0)
                             ) && ( dev->gadget.speed != USB_SPEED_UNKNOWN)) {
                         DEBUG (dev, "disconnect %s\n",
                                         dev->driver->driver.name);
@@ -2852,7 +2868,7 @@ static int net2280_probe (struct pci_dev *pdev, const struct pci_device_id *id)
 
         /* now all the pci goodies ... */
         if (pci_enable_device (pdev) < 0) {
-                retval = -ENODEV;
+                retval = -ENODEV;
                 goto done;
         }
         dev->enabled = 1;
@@ -2870,6 +2886,10 @@ static int net2280_probe (struct pci_dev *pdev, const struct pci_device_id *id)
         }
         dev->region = 1;
 
+        /* FIXME provide firmware download interface to put
+         * 8051 code into the chip, e.g. to turn on PCI PM.
+         */
+
         base = ioremap_nocache (resource, len);
         if (base == NULL) {
                 DEBUG (dev, "can't map memory\n");
@@ -2984,16 +3004,16 @@ static void net2280_shutdown (struct pci_dev *pdev)
 
 /*-------------------------------------------------------------------------*/
 
-static struct pci_device_id pci_ids [] = { {
-        .class =        ((PCI_CLASS_SERIAL_USB << 8) | 0xfe),
-        .class_mask =   ~0,
+static const struct pci_device_id pci_ids [] = { {
+        .class =        ((PCI_CLASS_SERIAL_USB << 8) | 0xfe),
+        .class_mask =   ~0,
         .vendor =       0x17cc,
         .device =       0x2280,
         .subvendor =    PCI_ANY_ID,
         .subdevice =    PCI_ANY_ID,
 }, {
-        .class =        ((PCI_CLASS_SERIAL_USB << 8) | 0xfe),
-        .class_mask =   ~0,
+        .class =        ((PCI_CLASS_SERIAL_USB << 8) | 0xfe),
+        .class_mask =   ~0,
         .vendor =       0x17cc,
         .device =       0x2282,
         .subvendor =    PCI_ANY_ID,