[PATCH 4/5] PCI: Add max_vfs in sysfs per pci device where supports

[Yinghai Lu]

only pci device that support sriov will have max_vfs show up in /sys

when user set value in /sys, driver ops set_max_vfs will be called to enable
VF there.

Signed-off-by: Yinghai Lu <ying...@kernel.org>
---
 drivers/pci/pci-sysfs.c |   51 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pci.h     |    1 +
 2 files changed, 52 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index fbbb97f..9b6f409 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -458,6 +458,52 @@ boot_vga_show(struct device *dev, struct device_attribute 
*attr, char *buf)
 }
 struct device_attribute vga_attr = __ATTR_RO(boot_vga);
 
+static ssize_t
+max_vfs_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+       struct pci_dev *pdev = to_pci_dev(dev);
+
+       return sprintf(buf, "%u\n", pdev->max_vfs);
+}
+
+static void max_vfs_callback(struct device *dev)
+{
+       struct pci_dev *pdev = to_pci_dev(dev);
+
+       mutex_lock(&pci_remove_rescan_mutex);
+       if (pdev->is_added && dev->driver) {
+               struct pci_driver *pdrv;
+
+               pdrv = to_pci_driver(dev->driver);
+               if (pdrv->set_max_vfs)
+                       pdrv->set_max_vfs(pdev);
+
+       }
+       mutex_unlock(&pci_remove_rescan_mutex);
+}
+static ssize_t
+max_vfs_store(struct device *dev, struct device_attribute *attr,
+                const char *buf, size_t count)
+{
+       unsigned long val;
+       int err;
+       struct pci_dev *pdev = to_pci_dev(dev);
+
+       if (kstrtoul(buf, 0, &val) < 0)
+               return -EINVAL;
+
+       pdev->max_vfs = val;
+
+       err = device_schedule_callback(dev, max_vfs_callback);
+
+       if (err)
+               return err;
+
+       return count;
+}
+struct device_attribute max_vfs_attr =
+       __ATTR(max_vfs, 0644, max_vfs_show, max_vfs_store);
+
 static void
 pci_config_pm_runtime_get(struct pci_dev *pdev)
 {
@@ -1405,6 +1451,7 @@ late_initcall(pci_sysfs_init);
 
 static struct attribute *pci_dev_dev_attrs[] = {
        &vga_attr.attr,
+       &max_vfs_attr.attr,
        NULL,
 };
 
@@ -1418,6 +1465,10 @@ static umode_t pci_dev_attrs_are_visible(struct kobject 
*kobj,
                if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
                        return 0;
 
+       if (a == &max_vfs_attr.attr)
+               if (!pdev->is_physfn)
+                       return 0;
+
        return a->mode;
 }
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 7d70a5e..f7423d4 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -335,6 +335,7 @@ struct pci_dev {
        unsigned int    broken_intx_masking:1;
        unsigned int    io_window_1k:1; /* Intel P2P bridge 1K I/O windows */
        pci_dev_flags_t dev_flags;
+       unsigned int    max_vfs;
        atomic_t        enable_cnt;     /* pci_enable_device has been called */
 
        u32             saved_config_space[16]; /* config space saved at 
suspend time */
-- 
1.7.7

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