misc: hpilo: map iLO shared memory by PCI revision id

Starting from iLO ASIC 'Neches' with subsystem device id 0x00E4,
bar 5 is used for shared memory region mapping instead of bar 2
because bar 2 is made inaccessible after system POST for security
reason.

As this holds true for future iLO ASIC generations, it does not
make sense to map shared memory region according to the subsystem
device id of each following generations.

Map iLO shared memory region with PCI revision id that maps to the
iLO ASIC generation, starting from Neches (Rev 7).
Signed-off-by: Matt Hsiao <matt.hsiao@hpe.com>
Link: https://lore.kernel.org/r/20210531085551.26421-1-matt.hsiao@hpe.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/hpilo.c

@@ -693,6 +693,8 @@ static int ilo_map_device(struct pci_dev *pdev, struct ilo_hwinfo *hw)
 {
 	int bar;
 	unsigned long off;
+	u8 pci_rev_id;
+	int rc;
 
 	/* map the memory mapped i/o registers */
 	hw->mmio_vaddr = pci_iomap(pdev, 1, 0);
@@ -702,7 +704,13 @@ static int ilo_map_device(struct pci_dev *pdev, struct ilo_hwinfo *hw)
 	}
 
 	/* map the adapter shared memory region */
-	if (pdev->subsystem_device == 0x00E4) {
+	rc = pci_read_config_byte(pdev, PCI_REVISION_ID, &pci_rev_id);
+	if (rc != 0) {
+		dev_err(&pdev->dev, "Error reading PCI rev id: %d\n", rc);
+		goto out;
+	}
+
+	if (pci_rev_id >= PCI_REV_ID_NECHES) {
 		bar = 5;
 		/* Last 8k is reserved for CCBs */
 		off = pci_resource_len(pdev, bar) - 0x2000;

drivers/misc/hpilo.h

@@ -10,6 +10,9 @@
 
 #define ILO_NAME "hpilo"
 
+/* iLO ASIC PCI revision id */
+#define PCI_REV_ID_NECHES	7
+
 /* max number of open channel control blocks per device, hw limited to 32 */
 #define MAX_CCB	       24
 /* min number of open channel control blocks per device, hw limited to 32 */