1 files changed, 55 insertions, 22 deletions

diff --git a/drivers/platform/x86/p2sb.c b/drivers/platform/x86/p2sb.c
index d51eb0db0626..cbbb0f809704 100644
--- a/drivers/platform/x86/p2sb.c
+++ b/drivers/platform/x86/p2sb.c
@@ -43,6 +43,7 @@ struct p2sb_res_cache {
 };
 
 static struct p2sb_res_cache p2sb_resources[NR_P2SB_RES_CACHE];
+static bool p2sb_hidden_by_bios;
 
 static void p2sb_get_devfn(unsigned int *devfn)
 {
@@ -97,6 +98,12 @@ static void p2sb_scan_and_cache_devfn(struct pci_bus *bus, unsigned int devfn)
 
 static int p2sb_scan_and_cache(struct pci_bus *bus, unsigned int devfn)
 {
+	/*
+	 * The BIOS prevents the P2SB device from being enumerated by the PCI
+	 * subsystem, so we need to unhide and hide it back to lookup the BAR.
+	 */
+	pci_bus_write_config_dword(bus, devfn, P2SBC, 0);
+
 	/* Scan the P2SB device and cache its BAR0 */
 	p2sb_scan_and_cache_devfn(bus, devfn);
 
@@ -104,6 +111,8 @@ static int p2sb_scan_and_cache(struct pci_bus *bus, unsigned int devfn)
 	if (devfn == P2SB_DEVFN_GOLDMONT)
 		p2sb_scan_and_cache_devfn(bus, SPI_DEVFN_GOLDMONT);
 
+	pci_bus_write_config_dword(bus, devfn, P2SBC, P2SBC_HIDE);
+
 	if (!p2sb_valid_resource(&p2sb_resources[PCI_FUNC(devfn)].res))
 		return -ENOENT;
 
@@ -129,7 +138,7 @@ static int p2sb_cache_resources(void)
 	u32 value = P2SBC_HIDE;
 	struct pci_bus *bus;
 	u16 class;
-	int ret;
+	int ret = 0;
 
 	/* Get devfn for P2SB device itself */
 	p2sb_get_devfn(&devfn_p2sb);
@@ -152,22 +161,53 @@ static int p2sb_cache_resources(void)
 	 */
 	pci_lock_rescan_remove();
 
+	pci_bus_read_config_dword(bus, devfn_p2sb, P2SBC, &value);
+	p2sb_hidden_by_bios = value & P2SBC_HIDE;
+
 	/*
-	 * The BIOS prevents the P2SB device from being enumerated by the PCI
-	 * subsystem, so we need to unhide and hide it back to lookup the BAR.
-	 * Unhide the P2SB device here, if needed.
+	 * If the BIOS does not hide the P2SB device then its resources
+	 * are accesilble. Cache them only if the P2SB device is hidden.
 	 */
-	pci_bus_read_config_dword(bus, devfn_p2sb, P2SBC, &value);
-	if (value & P2SBC_HIDE)
-		pci_bus_write_config_dword(bus, devfn_p2sb, P2SBC, 0);
+	if (p2sb_hidden_by_bios)
+		ret = p2sb_scan_and_cache(bus, devfn_p2sb);
 
-	ret = p2sb_scan_and_cache(bus, devfn_p2sb);
+	pci_unlock_rescan_remove();
 
-	/* Hide the P2SB device, if it was hidden */
-	if (value & P2SBC_HIDE)
-		pci_bus_write_config_dword(bus, devfn_p2sb, P2SBC, P2SBC_HIDE);
+	return ret;
+}
 
-	pci_unlock_rescan_remove();
+static int p2sb_read_from_cache(struct pci_bus *bus, unsigned int devfn,
+				struct resource *mem)
+{
+	struct p2sb_res_cache *cache = &p2sb_resources[PCI_FUNC(devfn)];
+
+	if (cache->bus_dev_id != bus->dev.id)
+		return -ENODEV;
+
+	if (!p2sb_valid_resource(&cache->res))
+		return -ENOENT;
+
+	memcpy(mem, &cache->res, sizeof(*mem));
+
+	return 0;
+}
+
+static int p2sb_read_from_dev(struct pci_bus *bus, unsigned int devfn,
+			      struct resource *mem)
+{
+	struct pci_dev *pdev;
+	int ret = 0;
+
+	pdev = pci_get_slot(bus, devfn);
+	if (!pdev)
+		return -ENODEV;
+
+	if (p2sb_valid_resource(pci_resource_n(pdev, 0)))
+		p2sb_read_bar0(pdev, mem);
+	else
+		ret = -ENOENT;
+
+	pci_dev_put(pdev);
 
 	return ret;
 }
@@ -188,8 +228,6 @@ static int p2sb_cache_resources(void)
  */
 int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem)
 {
-	struct p2sb_res_cache *cache;
-
 	bus = p2sb_get_bus(bus);
 	if (!bus)
 		return -ENODEV;
@@ -197,15 +235,10 @@ int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem)
 	if (!devfn)
 		p2sb_get_devfn(&devfn);
 
-	cache = &p2sb_resources[PCI_FUNC(devfn)];
-	if (cache->bus_dev_id != bus->dev.id)
-		return -ENODEV;
+	if (p2sb_hidden_by_bios)
+		return p2sb_read_from_cache(bus, devfn, mem);
 
-	if (!p2sb_valid_resource(&cache->res))
-		return -ENOENT;
-
-	memcpy(mem, &cache->res, sizeof(*mem));
-	return 0;
+	return p2sb_read_from_dev(bus, devfn, mem);
 }
 EXPORT_SYMBOL_GPL(p2sb_bar);