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authorLogan Gunthorpe <logang@deltatee.com>2018-10-04 15:27:38 -0600
committerBjorn Helgaas <bhelgaas@google.com>2018-10-17 12:18:17 -0500
commit2d7bc010f450d803db9fed1a25da6144ff6140d3 (patch)
treed54ab047d59ef11976e6c0929e7df9eb89397e39 /drivers/pci/p2pdma.c
parent977196b8c5b20b901acb0042579e30d7fa55790a (diff)
PCI/P2PDMA: Introduce configfs/sysfs enable attribute helpers
Users of the P2PDMA infrastructure will typically need a way for the user to tell the kernel to use P2P resources. Typically this will be a simple on/off boolean operation but sometimes it may be desirable for the user to specify the exact device to use for the P2P operation. Add new helpers for attributes which take a boolean or a PCI device. Any boolean as accepted by strtobool() turn P2P on or off (such as 'y', 'n', '1', '0', etc). Specifying a full PCI device name/BDF will select the specific device. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'drivers/pci/p2pdma.c')
-rw-r--r--drivers/pci/p2pdma.c82
1 files changed, 82 insertions, 0 deletions
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 09b3146c145c..ae3c5b25dcc7 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -8,6 +8,8 @@
* Copyright (c) 2018, Eideticom Inc.
*/
+#define pr_fmt(fmt) "pci-p2pdma: " fmt
+#include <linux/ctype.h>
#include <linux/pci-p2pdma.h>
#include <linux/module.h>
#include <linux/slab.h>
@@ -721,3 +723,83 @@ int pci_p2pdma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
return nents;
}
EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg);
+
+/**
+ * pci_p2pdma_enable_store - parse a configfs/sysfs attribute store
+ * to enable p2pdma
+ * @page: contents of the value to be stored
+ * @p2p_dev: returns the PCI device that was selected to be used
+ * (if one was specified in the stored value)
+ * @use_p2pdma: returns whether to enable p2pdma or not
+ *
+ * Parses an attribute value to decide whether to enable p2pdma.
+ * The value can select a PCI device (using it's full BDF device
+ * name) or a boolean (in any format strtobool() accepts). A false
+ * value disables p2pdma, a true value expects the caller
+ * to automatically find a compatible device and specifying a PCI device
+ * expects the caller to use the specific provider.
+ *
+ * pci_p2pdma_enable_show() should be used as the show operation for
+ * the attribute.
+ *
+ * Returns 0 on success
+ */
+int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
+ bool *use_p2pdma)
+{
+ struct device *dev;
+
+ dev = bus_find_device_by_name(&pci_bus_type, NULL, page);
+ if (dev) {
+ *use_p2pdma = true;
+ *p2p_dev = to_pci_dev(dev);
+
+ if (!pci_has_p2pmem(*p2p_dev)) {
+ pci_err(*p2p_dev,
+ "PCI device has no peer-to-peer memory: %s\n",
+ page);
+ pci_dev_put(*p2p_dev);
+ return -ENODEV;
+ }
+
+ return 0;
+ } else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) {
+ /*
+ * If the user enters a PCI device that doesn't exist
+ * like "0000:01:00.1", we don't want strtobool to think
+ * it's a '0' when it's clearly not what the user wanted.
+ * So we require 0's and 1's to be exactly one character.
+ */
+ } else if (!strtobool(page, use_p2pdma)) {
+ return 0;
+ }
+
+ pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page);
+ return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store);
+
+/**
+ * pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating
+ * whether p2pdma is enabled
+ * @page: contents of the stored value
+ * @p2p_dev: the selected p2p device (NULL if no device is selected)
+ * @use_p2pdma: whether p2pdme has been enabled
+ *
+ * Attributes that use pci_p2pdma_enable_store() should use this function
+ * to show the value of the attribute.
+ *
+ * Returns 0 on success
+ */
+ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
+ bool use_p2pdma)
+{
+ if (!use_p2pdma)
+ return sprintf(page, "0\n");
+
+ if (!p2p_dev)
+ return sprintf(page, "1\n");
+
+ return sprintf(page, "%s\n", pci_name(p2p_dev));
+}
+EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show);