USB: xhci: Scratchpad buffer allocation

Allocates and initializes the scratchpad buffer array (XHCI 4.20). This is an
array of 64-bit DMA addresses to scratch pages that the controller may use
during operation. The number of pages is specified in the "Max Scratchpad
Buffers" field of HCSPARAMS2. The DMA address of this array is written into
slot 0 of the DCBAA.

Signed-off-by: John Youn <[e-mail]>
Acked-by: Sarah Sharp <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/xhci-mem.c

···
 	 */
 }
 
+/* Set up the scratchpad buffer array and scratchpad buffers, if needed. */
+static int scratchpad_alloc(struct xhci_hcd *xhci, gfp_t flags)
+{
+	int i;
+	struct device *dev = xhci_to_hcd(xhci)->self.controller;
+	int num_sp = HCS_MAX_SCRATCHPAD(xhci->hcs_params2);
+
+	xhci_dbg(xhci, "Allocating %d scratchpad buffers\n", num_sp);
+
+	if (!num_sp)
+		return 0;
+
+	xhci->scratchpad = kzalloc(sizeof(*xhci->scratchpad), flags);
+	if (!xhci->scratchpad)
+		goto fail_sp;
+
+	xhci->scratchpad->sp_array =
+		pci_alloc_consistent(to_pci_dev(dev),
+				     num_sp * sizeof(u64),
+				     &xhci->scratchpad->sp_dma);
+	if (!xhci->scratchpad->sp_array)
+		goto fail_sp2;
+
+	xhci->scratchpad->sp_buffers = kzalloc(sizeof(void *) * num_sp, flags);
+	if (!xhci->scratchpad->sp_buffers)
+		goto fail_sp3;
+
+	xhci->scratchpad->sp_dma_buffers =
+		kzalloc(sizeof(dma_addr_t) * num_sp, flags);
+
+	if (!xhci->scratchpad->sp_dma_buffers)
+		goto fail_sp4;
+
+	xhci->dcbaa->dev_context_ptrs[0] = xhci->scratchpad->sp_dma;
+	for (i = 0; i < num_sp; i++) {
+		dma_addr_t dma;
+		void *buf = pci_alloc_consistent(to_pci_dev(dev),
+						 xhci->page_size, &dma);
+		if (!buf)
+			goto fail_sp5;
+
+		xhci->scratchpad->sp_array[i] = dma;
+		xhci->scratchpad->sp_buffers[i] = buf;
+		xhci->scratchpad->sp_dma_buffers[i] = dma;
+	}
+
+	return 0;
+
+ fail_sp5:
+	for (i = i - 1; i >= 0; i--) {
+		pci_free_consistent(to_pci_dev(dev), xhci->page_size,
+				    xhci->scratchpad->sp_buffers[i],
+				    xhci->scratchpad->sp_dma_buffers[i]);
+	}
+	kfree(xhci->scratchpad->sp_dma_buffers);
+
+ fail_sp4:
+	kfree(xhci->scratchpad->sp_buffers);
+
+ fail_sp3:
+	pci_free_consistent(to_pci_dev(dev), num_sp * sizeof(u64),
+			    xhci->scratchpad->sp_array,
+			    xhci->scratchpad->sp_dma);
+
+ fail_sp2:
+	kfree(xhci->scratchpad);
+	xhci->scratchpad = NULL;
+
+ fail_sp:
+	return -ENOMEM;
+}
+
+static void scratchpad_free(struct xhci_hcd *xhci)
+{
+	int num_sp;
+	int i;
+	struct pci_dev	*pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);
+
+	if (!xhci->scratchpad)
+		return;
+
+	num_sp = HCS_MAX_SCRATCHPAD(xhci->hcs_params2);
+
+	for (i = 0; i < num_sp; i++) {
+		pci_free_consistent(pdev, xhci->page_size,
+				    xhci->scratchpad->sp_buffers[i],
+				    xhci->scratchpad->sp_dma_buffers[i]);
+	}
+	kfree(xhci->scratchpad->sp_dma_buffers);
+	kfree(xhci->scratchpad->sp_buffers);
+	pci_free_consistent(pdev, num_sp * sizeof(u64),
+			    xhci->scratchpad->sp_array,
+			    xhci->scratchpad->sp_dma);
+	kfree(xhci->scratchpad);
+	xhci->scratchpad = NULL;
+}
+
 void xhci_mem_cleanup(struct xhci_hcd *xhci)
 {
 	struct pci_dev	*pdev = to_pci_dev(xhci_to_hcd(xhci)->self.controller);
···
 
 	xhci->page_size = 0;
 	xhci->page_shift = 0;
+	scratchpad_free(xhci);
 }
 
 int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
···
 	for (i = 0; i < MAX_HC_SLOTS; ++i)
 		xhci->devs[i] = 0;
 
+	if (scratchpad_alloc(xhci, flags))
+		goto fail;
+
 	return 0;
+
 fail:
 	xhci_warn(xhci, "Couldn't initialize memory\n");
 	xhci_mem_cleanup(xhci);

drivers/usb/host/xhci.h

···
 #define HCS_ERST_MAX(p)		(((p) >> 4) & 0xf)
 /* bit 26 Scratchpad restore - for save/restore HW state - not used yet */
 /* bits 27:31 number of Scratchpad buffers SW must allocate for the HW */
+#define HCS_MAX_SCRATCHPAD(p)   (((p) >> 27) & 0x1f)
 
 /* HCSPARAMS3 - hcs_params3 - bitmasks */
 /* bits 0:7, Max U1 to U0 latency for the roothub ports */
···
 	unsigned int		erst_size;
 };
 
+struct xhci_scratchpad {
+	u64 *sp_array;
+	dma_addr_t sp_dma;
+	void **sp_buffers;
+	dma_addr_t *sp_dma_buffers;
+};
+
 /*
  * Each segment table entry is 4*32bits long.  1K seems like an ok size:
  * (1K bytes * 8bytes/bit) / (4*32 bits) = 64 segment entries in the table,
···
 	struct xhci_ring	*cmd_ring;
 	struct xhci_ring	*event_ring;
 	struct xhci_erst	erst;
+	/* Scratchpad */
+	struct xhci_scratchpad  *scratchpad;
+
 	/* slot enabling and address device helpers */
 	struct completion	addr_dev;
 	int slot_id;