PCI: Expose PCI VPD through sysfs

Vital Product Data (VPD) may be exposed by PCI devices in several
ways.  It is generally unsafe to read this information through the
existing interfaces to user-land because of stateful interfaces.

This adds:
- abstract operations for VPD access (struct pci_vpd_ops)
- VPD state information in struct pci_dev (struct pci_vpd)
- an implementation of the VPD access method specified in PCI 2.2
  (in access.c)
- a 'vpd' binary file in sysfs directories for PCI devices with VPD
  operations defined

It adds a probe for PCI 2.2 VPD in pci_scan_device() and release of
VPD state in pci_release_dev().

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 166 insertions, 0 deletions

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index fc405f0165d9..ec8f7002b09d 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -1,3 +1,4 @@
+#include <linux/delay.h>
 #include <linux/pci.h>
 #include <linux/module.h>
 #include <linux/sched.h>
@@ -126,6 +127,171 @@ PCI_USER_WRITE_CONFIG(byte, u8)
 PCI_USER_WRITE_CONFIG(word, u16)
 PCI_USER_WRITE_CONFIG(dword, u32)
 
+/* VPD access through PCI 2.2+ VPD capability */
+
+#define PCI_VPD_PCI22_SIZE (PCI_VPD_ADDR_MASK + 1)
+
+struct pci_vpd_pci22 {
+        struct pci_vpd base;
+        spinlock_t lock; /* controls access to hardware and the flags */
+        u8      cap;
+        bool    busy;
+        bool    flag; /* value of F bit to wait for */
+};
+
+/* Wait for last operation to complete */
+static int pci_vpd_pci22_wait(struct pci_dev *dev)
+{
+        struct pci_vpd_pci22 *vpd =
+                container_of(dev->vpd, struct pci_vpd_pci22, base);
+        u16 flag, status;
+        int wait;
+        int ret;
+
+        if (!vpd->busy)
+                return 0;
+
+        flag = vpd->flag ? PCI_VPD_ADDR_F : 0;
+        wait = vpd->flag ? 10 : 1000; /* read: 100 us; write: 10 ms */
+        for (;;) {
+                ret = pci_user_read_config_word(dev,
+                                                vpd->cap + PCI_VPD_ADDR,
+                                                &status);
+                if (ret < 0)
+                        return ret;
+                if ((status & PCI_VPD_ADDR_F) == flag) {
+                        vpd->busy = false;
+                        return 0;
+                }
+                if (wait-- == 0)
+                        return -ETIMEDOUT;
+                udelay(10);
+        }
+}
+
+static int pci_vpd_pci22_read(struct pci_dev *dev, int pos, int size,
+                              char *buf)
+{
+        struct pci_vpd_pci22 *vpd =
+                container_of(dev->vpd, struct pci_vpd_pci22, base);
+        u32 val;
+        int ret;
+        int begin, end, i;
+
+        if (pos < 0 || pos > PCI_VPD_PCI22_SIZE ||
+            size > PCI_VPD_PCI22_SIZE  - pos)
+                return -EINVAL;
+        if (size == 0)
+                return 0;
+
+        spin_lock_irq(&vpd->lock);
+        ret = pci_vpd_pci22_wait(dev);
+        if (ret < 0)
+                goto out;
+        ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
+                                         pos & ~3);
+        if (ret < 0)
+                goto out;
+        vpd->busy = true;
+        vpd->flag = 1;
+        ret = pci_vpd_pci22_wait(dev);
+        if (ret < 0)
+                goto out;
+        ret = pci_user_read_config_dword(dev, vpd->cap + PCI_VPD_DATA,
+                                         &val);
+out:
+        spin_unlock_irq(&vpd->lock);
+        if (ret < 0)
+                return ret;
+
+        /* Convert to bytes */
+        begin = pos & 3;
+        end = min(4, begin + size);
+        for (i = 0; i < end; ++i) {
+                if (i >= begin)
+                        *buf++ = val;
+                val >>= 8;
+        }
+        return end - begin;
+}
+
+static int pci_vpd_pci22_write(struct pci_dev *dev, int pos, int size,
+                               const char *buf)
+{
+        struct pci_vpd_pci22 *vpd =
+                container_of(dev->vpd, struct pci_vpd_pci22, base);
+        u32 val;
+        int ret;
+
+        if (pos < 0 || pos > PCI_VPD_PCI22_SIZE || pos & 3 ||
+            size > PCI_VPD_PCI22_SIZE - pos || size < 4)
+                return -EINVAL;
+
+        val = (u8) *buf++;
+        val |= ((u8) *buf++) << 8;
+        val |= ((u8) *buf++) << 16;
+        val |= ((u32)(u8) *buf++) << 24;
+
+        spin_lock_irq(&vpd->lock);
+        ret = pci_vpd_pci22_wait(dev);
+        if (ret < 0)
+                goto out;
+        ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA,
+                                          val);
+        if (ret < 0)
+                goto out;
+        ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
+                                         pos | PCI_VPD_ADDR_F);
+        if (ret < 0)
+                goto out;
+        vpd->busy = true;
+        vpd->flag = 0;
+        ret = pci_vpd_pci22_wait(dev);
+out:
+        spin_unlock_irq(&vpd->lock);
+        if (ret < 0)
+                return ret;
+
+        return 4;
+}
+
+static int pci_vpd_pci22_get_size(struct pci_dev *dev)
+{
+        return PCI_VPD_PCI22_SIZE;
+}
+
+static void pci_vpd_pci22_release(struct pci_dev *dev)
+{
+        kfree(container_of(dev->vpd, struct pci_vpd_pci22, base));
+}
+
+static struct pci_vpd_ops pci_vpd_pci22_ops = {
+        .read = pci_vpd_pci22_read,
+        .write = pci_vpd_pci22_write,
+        .get_size = pci_vpd_pci22_get_size,
+        .release = pci_vpd_pci22_release,
+};
+
+int pci_vpd_pci22_init(struct pci_dev *dev)
+{
+        struct pci_vpd_pci22 *vpd;
+        u8 cap;
+
+        cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
+        if (!cap)
+                return -ENODEV;
+        vpd = kzalloc(sizeof(*vpd), GFP_ATOMIC);
+        if (!vpd)
+                return -ENOMEM;
+
+        vpd->base.ops = &pci_vpd_pci22_ops;
+        spin_lock_init(&vpd->lock);
+        vpd->cap = cap;
+        vpd->busy = false;
+        dev->vpd = &vpd->base;
+        return 0;
+}
+
 /**
  * pci_block_user_cfg_access - Block userspace PCI config reads/writes
  * @dev:        pci device struct