x86: PAT export resource_wc in pci sysfs

For the ranges with IORESOURCE_PREFETCH, export a new resource_wc interface in
pci /sysfs along with resource (which is uncached).

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 64 insertions, 22 deletions

diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
index 5daa2aaec2c5..68ef48839c04 100644
--- a/Documentation/filesystems/sysfs-pci.txt
+++ b/Documentation/filesystems/sysfs-pci.txt
@@ -36,6 +36,7 @@ files, each with their own function.
        local_cpus          nearby CPU mask (cpumask, ro)
        resource            PCI resource host addresses (ascii, ro)
        resource0..N        PCI resource N, if present (binary, mmap)
+       resource0_wc..N_wc  PCI WC map resource N, if prefetchable (binary, mmap)
        rom                 PCI ROM resource, if present (binary, ro)
        subsystem_device    PCI subsystem device (ascii, ro)
        subsystem_vendor    PCI subsystem vendor (ascii, ro)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 271d41cc05ab..9ec7d3977a82 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -489,13 +489,14 @@ pci_mmap_legacy_mem(struct kobject *kobj, struct bin_attribute *attr,
  * @kobj: kobject for mapping
  * @attr: struct bin_attribute for the file being mapped
  * @vma: struct vm_area_struct passed into the mmap
+ * @write_combine: 1 for write_combine mapping
  *
  * Use the regular PCI mapping routines to map a PCI resource into userspace.
  * FIXME: write combining?  maybe automatic for prefetchable regions?
  */
 static int
 pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
-                  struct vm_area_struct *vma)
+                  struct vm_area_struct *vma, int write_combine)
 {
         struct pci_dev *pdev = to_pci_dev(container_of(kobj,
                                                        struct device, kobj));
@@ -518,7 +519,21 @@ pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
         vma->vm_pgoff += start >> PAGE_SHIFT;
         mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
 
-        return pci_mmap_page_range(pdev, vma, mmap_type, 0);
+        return pci_mmap_page_range(pdev, vma, mmap_type, write_combine);
+}
+
+static int
+pci_mmap_resource_uc(struct kobject *kobj, struct bin_attribute *attr,
+                     struct vm_area_struct *vma)
+{
+        return pci_mmap_resource(kobj, attr, vma, 0);
+}
+
+static int
+pci_mmap_resource_wc(struct kobject *kobj, struct bin_attribute *attr,
+                     struct vm_area_struct *vma)
+{
+        return pci_mmap_resource(kobj, attr, vma, 1);
 }
 
 /**
@@ -541,9 +556,46 @@ pci_remove_resource_files(struct pci_dev *pdev)
                         sysfs_remove_bin_file(&pdev->dev.kobj, res_attr);
                         kfree(res_attr);
                 }
+
+                res_attr = pdev->res_attr_wc[i];
+                if (res_attr) {
+                        sysfs_remove_bin_file(&pdev->dev.kobj, res_attr);
+                        kfree(res_attr);
+                }
         }
 }
 
+static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
+{
+        /* allocate attribute structure, piggyback attribute name */
+        int name_len = write_combine ? 13 : 10;
+        struct bin_attribute *res_attr;
+        int retval;
+
+        res_attr = kzalloc(sizeof(*res_attr) + name_len, GFP_ATOMIC);
+        if (res_attr) {
+                char *res_attr_name = (char *)(res_attr + 1);
+
+                if (write_combine) {
+                        pdev->res_attr_wc[num] = res_attr;
+                        sprintf(res_attr_name, "resource%d_wc", num);
+                        res_attr->mmap = pci_mmap_resource_wc;
+                } else {
+                        pdev->res_attr[num] = res_attr;
+                        sprintf(res_attr_name, "resource%d", num);
+                        res_attr->mmap = pci_mmap_resource_uc;
+                }
+                res_attr->attr.name = res_attr_name;
+                res_attr->attr.mode = S_IRUSR | S_IWUSR;
+                res_attr->size = pci_resource_len(pdev, num);
+                res_attr->private = &pdev->resource[num];
+                retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
+        } else
+                retval = -ENOMEM;
+
+        return retval;
+}
+
 /**
  * pci_create_resource_files - create resource files in sysfs for @dev
  * @dev: dev in question
@@ -557,31 +609,19 @@ static int pci_create_resource_files(struct pci_dev *pdev)
 
         /* Expose the PCI resources from this device as files */
         for (i = 0; i < PCI_ROM_RESOURCE; i++) {
-                struct bin_attribute *res_attr;
 
                 /* skip empty resources */
                 if (!pci_resource_len(pdev, i))
                         continue;
 
-                /* allocate attribute structure, piggyback attribute name */
-                res_attr = kzalloc(sizeof(*res_attr) + 10, GFP_ATOMIC);
-                if (res_attr) {
-                        char *res_attr_name = (char *)(res_attr + 1);
-
-                        pdev->res_attr[i] = res_attr;
-                        sprintf(res_attr_name, "resource%d", i);
-                        res_attr->attr.name = res_attr_name;
-                        res_attr->attr.mode = S_IRUSR | S_IWUSR;
-                        res_attr->size = pci_resource_len(pdev, i);
-                        res_attr->mmap = pci_mmap_resource;
-                        res_attr->private = &pdev->resource[i];
-                        retval = sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
-                        if (retval) {
-                                pci_remove_resource_files(pdev);
-                                return retval;
-                        }
-                } else {
-                        return -ENOMEM;
+                retval = pci_create_attr(pdev, i, 0);
+                /* for prefetchable resources, create a WC mappable file */
+                if (!retval && pdev->resource[i].flags & IORESOURCE_PREFETCH)
+                        retval = pci_create_attr(pdev, i, 1);
+
+                if (retval) {
+                        pci_remove_resource_files(pdev);
+                        return retval;
                 }
         }
         return 0;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 509159bcd4e7..d18b1dd49fab 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -206,6 +206,7 @@ struct pci_dev {
         struct bin_attribute *rom_attr; /* attribute descriptor for sysfs ROM entry */
         int rom_attr_enabled;           /* has display of the rom attribute been enabled? */
         struct bin_attribute *res_attr[DEVICE_COUNT_RESOURCE]; /* sysfs file for resources */
+        struct bin_attribute *res_attr_wc[DEVICE_COUNT_RESOURCE]; /* sysfs file for WC mapping of resources */
 #ifdef CONFIG_PCI_MSI
         struct list_head msi_list;
 #endif