PCI: Return u8 from pci_find_capability() and similar

PCI Capabilities are linked in a list that must appear in the first 256
bytes of config space.  Each capabilities list pointer is 8 bits.

Change the return type of pci_find_capability() and supporting functions
from int to u8 to match the specification.

[bhelgaas: change other related interfaces, fix HyperTransport typos]
Link: https://lore.kernel.org/r/20201129164626.12887-1-puranjay12@gmail.comSigned-off-by: Puranjay Mohan <puranjay12@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -399,8 +399,8 @@ static int pci_dev_str_match(struct pci_dev *dev, const char *p,
 	return 1;
 }
 
-static int __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn,
-				   u8 pos, int cap, int *ttl)
+static u8 __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn,
+				  u8 pos, int cap, int *ttl)
 {
 	u8 id;
 	u16 ent;
@@ -423,22 +423,22 @@ static int __pci_find_next_cap_ttl(struct pci_bus *bus, unsigned int devfn,
 	return 0;
 }
 
-static int __pci_find_next_cap(struct pci_bus *bus, unsigned int devfn,
-			       u8 pos, int cap)
+static u8 __pci_find_next_cap(struct pci_bus *bus, unsigned int devfn,
+			      u8 pos, int cap)
 {
 	int ttl = PCI_FIND_CAP_TTL;
 
 	return __pci_find_next_cap_ttl(bus, devfn, pos, cap, &ttl);
 }
 
-int pci_find_next_capability(struct pci_dev *dev, u8 pos, int cap)
+u8 pci_find_next_capability(struct pci_dev *dev, u8 pos, int cap)
 {
 	return __pci_find_next_cap(dev->bus, dev->devfn,
 				   pos + PCI_CAP_LIST_NEXT, cap);
 }
 EXPORT_SYMBOL_GPL(pci_find_next_capability);
 
-static int __pci_bus_find_cap_start(struct pci_bus *bus,
+static u8 __pci_bus_find_cap_start(struct pci_bus *bus,
 				    unsigned int devfn, u8 hdr_type)
 {
 	u16 status;
@@ -477,9 +477,9 @@ static int __pci_bus_find_cap_start(struct pci_bus *bus,
  *  %PCI_CAP_ID_PCIX         PCI-X
  *  %PCI_CAP_ID_EXP          PCI Express
  */
-int pci_find_capability(struct pci_dev *dev, int cap)
+u8 pci_find_capability(struct pci_dev *dev, int cap)
 {
-	int pos;
+	u8 pos;
 
 	pos = __pci_bus_find_cap_start(dev->bus, dev->devfn, dev->hdr_type);
 	if (pos)
@@ -502,10 +502,9 @@ EXPORT_SYMBOL(pci_find_capability);
  * device's PCI configuration space or 0 in case the device does not
  * support it.
  */
-int pci_bus_find_capability(struct pci_bus *bus, unsigned int devfn, int cap)
+u8 pci_bus_find_capability(struct pci_bus *bus, unsigned int devfn, int cap)
 {
-	int pos;
-	u8 hdr_type;
+	u8 hdr_type, pos;
 
 	pci_bus_read_config_byte(bus, devfn, PCI_HEADER_TYPE, &hdr_type);
 
@@ -623,7 +622,7 @@ u64 pci_get_dsn(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_get_dsn);
 
-static int __pci_find_next_ht_cap(struct pci_dev *dev, int pos, int ht_cap)
+static u8 __pci_find_next_ht_cap(struct pci_dev *dev, u8 pos, int ht_cap)
 {
 	int rc, ttl = PCI_FIND_CAP_TTL;
 	u8 cap, mask;
@@ -650,11 +649,12 @@ static int __pci_find_next_ht_cap(struct pci_dev *dev, int pos, int ht_cap)
 
 	return 0;
 }
+
 /**
- * pci_find_next_ht_capability - query a device's Hypertransport capabilities
+ * pci_find_next_ht_capability - query a device's HyperTransport capabilities
  * @dev: PCI device to query
  * @pos: Position from which to continue searching
- * @ht_cap: Hypertransport capability code
+ * @ht_cap: HyperTransport capability code
  *
  * To be used in conjunction with pci_find_ht_capability() to search for
  * all capabilities matching @ht_cap. @pos should always be a value returned
@@ -663,26 +663,26 @@ static int __pci_find_next_ht_cap(struct pci_dev *dev, int pos, int ht_cap)
  * NB. To be 100% safe against broken PCI devices, the caller should take
  * steps to avoid an infinite loop.
  */
-int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap)
+u8 pci_find_next_ht_capability(struct pci_dev *dev, u8 pos, int ht_cap)
 {
 	return __pci_find_next_ht_cap(dev, pos + PCI_CAP_LIST_NEXT, ht_cap);
 }
 EXPORT_SYMBOL_GPL(pci_find_next_ht_capability);
 
 /**
- * pci_find_ht_capability - query a device's Hypertransport capabilities
+ * pci_find_ht_capability - query a device's HyperTransport capabilities
  * @dev: PCI device to query
- * @ht_cap: Hypertransport capability code
+ * @ht_cap: HyperTransport capability code
  *
- * Tell if a device supports a given Hypertransport capability.
+ * Tell if a device supports a given HyperTransport capability.
  * Returns an address within the device's PCI configuration space
  * or 0 in case the device does not support the request capability.
  * The address points to the PCI capability, of type PCI_CAP_ID_HT,
- * which has a Hypertransport capability matching @ht_cap.
+ * which has a HyperTransport capability matching @ht_cap.
  */
-int pci_find_ht_capability(struct pci_dev *dev, int ht_cap)
+u8 pci_find_ht_capability(struct pci_dev *dev, int ht_cap)
 {
-	int pos;
+	u8 pos;
 
 	pos = __pci_bus_find_cap_start(dev->bus, dev->devfn, dev->hdr_type);
 	if (pos)

include/linux/pci.h

@@ -1064,12 +1064,13 @@ void pci_sort_breadthfirst(void);
 
 /* Generic PCI functions exported to card drivers */
 
-int pci_find_capability(struct pci_dev *dev, int cap);
-int pci_find_next_capability(struct pci_dev *dev, u8 pos, int cap);
+u8 pci_bus_find_capability(struct pci_bus *bus, unsigned int devfn, int cap);
+u8 pci_find_capability(struct pci_dev *dev, int cap);
+u8 pci_find_next_capability(struct pci_dev *dev, u8 pos, int cap);
+u8 pci_find_ht_capability(struct pci_dev *dev, int ht_cap);
+u8 pci_find_next_ht_capability(struct pci_dev *dev, u8 pos, int ht_cap);
 int pci_find_ext_capability(struct pci_dev *dev, int cap);
 int pci_find_next_ext_capability(struct pci_dev *dev, int pos, int cap);
-int pci_find_ht_capability(struct pci_dev *dev, int ht_cap);
-int pci_find_next_ht_capability(struct pci_dev *dev, int pos, int ht_cap);
 struct pci_bus *pci_find_next_bus(const struct pci_bus *from);
 
 u64 pci_get_dsn(struct pci_dev *dev);
@@ -1280,7 +1281,6 @@ void set_pcie_port_type(struct pci_dev *pdev);
 void set_pcie_hotplug_bridge(struct pci_dev *pdev);
 
 /* Functions for PCI Hotplug drivers to use */
-int pci_bus_find_capability(struct pci_bus *bus, unsigned int devfn, int cap);
 unsigned int pci_rescan_bus_bridge_resize(struct pci_dev *bridge);
 unsigned int pci_rescan_bus(struct pci_bus *bus);
 void pci_lock_rescan_remove(void);
@@ -1720,7 +1720,7 @@ static inline int __pci_register_driver(struct pci_driver *drv,
 static inline int pci_register_driver(struct pci_driver *drv)
 { return 0; }
 static inline void pci_unregister_driver(struct pci_driver *drv) { }
-static inline int pci_find_capability(struct pci_dev *dev, int cap)
+static inline u8 pci_find_capability(struct pci_dev *dev, int cap)
 { return 0; }
 static inline int pci_find_next_capability(struct pci_dev *dev, u8 post,
 					   int cap)