PCI/sysfs: add per pci device msi[x] irq listing (v5)

This patch adds a per-pci-device subdirectory in sysfs called:
/sys/bus/pci/devices/<device>/msi_irqs

This sub-directory exports the set of msi vectors allocated by a given
pci device, by creating a numbered sub-directory for each vector beneath
msi_irqs.  For each vector various attributes can be exported.
Currently the only attribute is called mode, which tracks the
operational mode of that vector (msi vs. msix)

Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

4 files changed, 133 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index 349ecf26ce10..34f51100f029 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -66,6 +66,24 @@ Description:
                 re-discover previously removed devices.
                 Depends on CONFIG_HOTPLUG.
 
+What:           /sys/bus/pci/devices/.../msi_irqs/
+Date:           September, 2011
+Contact:        Neil Horman <nhorman@tuxdriver.com>
+Description:
+                The /sys/devices/.../msi_irqs directory contains a variable set
+                of sub-directories, with each sub-directory being named after a
+                corresponding msi irq vector allocated to that device.  Each
+                numbered sub-directory N contains attributes of that irq.
+                Note that this directory is not created for device drivers which
+                do not support msi irqs
+
+What:           /sys/bus/pci/devices/.../msi_irqs/<N>/mode
+Date:           September 2011
+Contact:        Neil Horman <nhorman@tuxdriver.com>
+Description:
+                This attribute indicates the mode that the irq vector named by
+                the parent directory is in (msi vs. msix)
+
 What:           /sys/bus/pci/devices/.../remove
 Date:           January 2009
 Contact:        Linux PCI developers <linux-pci@vger.kernel.org>
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 0e6d04d7ba4f..e6b6b9c67023 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -323,6 +323,8 @@ static void free_msi_irqs(struct pci_dev *dev)
                         if (list_is_last(&entry->list, &dev->msi_list))
                                 iounmap(entry->mask_base);
                 }
+                kobject_del(&entry->kobj);
+                kobject_put(&entry->kobj);
                 list_del(&entry->list);
                 kfree(entry);
         }
@@ -403,6 +405,98 @@ void pci_restore_msi_state(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_restore_msi_state);
 
+
+#define to_msi_attr(obj) container_of(obj, struct msi_attribute, attr)
+#define to_msi_desc(obj) container_of(obj, struct msi_desc, kobj)
+
+struct msi_attribute {
+        struct attribute        attr;
+        ssize_t (*show)(struct msi_desc *entry, struct msi_attribute *attr,
+                        char *buf);
+        ssize_t (*store)(struct msi_desc *entry, struct msi_attribute *attr,
+                         const char *buf, size_t count);
+};
+
+static ssize_t show_msi_mode(struct msi_desc *entry, struct msi_attribute *atr,
+                             char *buf)
+{
+        return sprintf(buf, "%s\n", entry->msi_attrib.is_msix ? "msix" : "msi");
+}
+
+static ssize_t msi_irq_attr_show(struct kobject *kobj,
+                                 struct attribute *attr, char *buf)
+{
+        struct msi_attribute *attribute = to_msi_attr(attr);
+        struct msi_desc *entry = to_msi_desc(kobj);
+
+        if (!attribute->show)
+                return -EIO;
+
+        return attribute->show(entry, attribute, buf);
+}
+
+static const struct sysfs_ops msi_irq_sysfs_ops = {
+        .show = msi_irq_attr_show,
+};
+
+static struct msi_attribute mode_attribute =
+        __ATTR(mode, S_IRUGO, show_msi_mode, NULL);
+
+
+struct attribute *msi_irq_default_attrs[] = {
+        &mode_attribute.attr,
+        NULL
+};
+
+void msi_kobj_release(struct kobject *kobj)
+{
+        struct msi_desc *entry = to_msi_desc(kobj);
+
+        pci_dev_put(entry->dev);
+}
+
+static struct kobj_type msi_irq_ktype = {
+        .release = msi_kobj_release,
+        .sysfs_ops = &msi_irq_sysfs_ops,
+        .default_attrs = msi_irq_default_attrs,
+};
+
+static int populate_msi_sysfs(struct pci_dev *pdev)
+{
+        struct msi_desc *entry;
+        struct kobject *kobj;
+        int ret;
+        int count = 0;
+
+        pdev->msi_kset = kset_create_and_add("msi_irqs", NULL, &pdev->dev.kobj);
+        if (!pdev->msi_kset)
+                return -ENOMEM;
+
+        list_for_each_entry(entry, &pdev->msi_list, list) {
+                kobj = &entry->kobj;
+                kobj->kset = pdev->msi_kset;
+                pci_dev_get(pdev);
+                ret = kobject_init_and_add(kobj, &msi_irq_ktype, NULL,
+                                     "%u", entry->irq);
+                if (ret)
+                        goto out_unroll;
+
+                count++;
+        }
+
+        return 0;
+
+out_unroll:
+        list_for_each_entry(entry, &pdev->msi_list, list) {
+                if (!count)
+                        break;
+                kobject_del(&entry->kobj);
+                kobject_put(&entry->kobj);
+                count--;
+        }
+        return ret;
+}
+
 /**
  * msi_capability_init - configure device's MSI capability structure
  * @dev: pointer to the pci_dev data structure of MSI device function
@@ -454,6 +548,13 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
                 return ret;
         }
 
+        ret = populate_msi_sysfs(dev);
+        if (ret) {
+                msi_mask_irq(entry, mask, ~mask);
+                free_msi_irqs(dev);
+                return ret;
+        }
+
         /* Set MSI enabled bits  */
         pci_intx_for_msi(dev, 0);
         msi_set_enable(dev, pos, 1);
@@ -574,6 +675,12 @@ static int msix_capability_init(struct pci_dev *dev,
 
         msix_program_entries(dev, entries);
 
+        ret = populate_msi_sysfs(dev);
+        if (ret) {
+                ret = 0;
+                goto error;
+        }
+
         /* Set MSI-X enabled bits and unmask the function */
         pci_intx_for_msi(dev, 0);
         dev->msix_enabled = 1;
@@ -732,6 +839,8 @@ void pci_disable_msi(struct pci_dev *dev)
 
         pci_msi_shutdown(dev);
         free_msi_irqs(dev);
+        kset_unregister(dev->msi_kset);
+        dev->msi_kset = NULL;
 }
 EXPORT_SYMBOL(pci_disable_msi);
 
@@ -830,6 +939,8 @@ void pci_disable_msix(struct pci_dev *dev)
 
         pci_msix_shutdown(dev);
         free_msi_irqs(dev);
+        kset_unregister(dev->msi_kset);
+        dev->msi_kset = NULL;
 }
 EXPORT_SYMBOL(pci_disable_msix);
 
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 05acced439a3..ce93a341337d 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -1,6 +1,7 @@
 #ifndef LINUX_MSI_H
 #define LINUX_MSI_H
 
+#include <linux/kobject.h>
 #include <linux/list.h>
 
 struct msi_msg {
@@ -44,6 +45,8 @@ struct msi_desc {
 
         /* Last set MSI message */
         struct msi_msg msg;
+
+        struct kobject kobj;
 };
 
 /*
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 7cda65b5f798..84225c756bd1 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -336,6 +336,7 @@ struct pci_dev {
         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;
+        struct kset *msi_kset;
 #endif
         struct pci_vpd *vpd;
 #ifdef CONFIG_PCI_ATS