pci: Add a function to find a device by class

There is an existing function prototype in the header file but it is not
implemented. Implement something similar.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/pci/pci.c

@@ -15,6 +15,7 @@
 #include <common.h>
 
 #include <command.h>
+#include <errno.h>
 #include <asm/processor.h>
 #include <asm/io.h>
 #include <pci.h>
@@ -236,6 +237,48 @@ pci_dev_t pci_find_devices(struct pci_device_id *ids, int index)
 	return -1;
 }
 
+pci_dev_t pci_find_class(uint find_class, int index)
+{
+	int bus;
+	int devnum;
+	pci_dev_t bdf;
+	uint32_t class;
+
+	for (bus = 0; bus <= pci_last_busno(); bus++) {
+		for (devnum = 0; devnum < PCI_MAX_PCI_DEVICES - 1; devnum++) {
+			pci_read_config_dword(PCI_BDF(bus, devnum, 0),
+					      PCI_CLASS_REVISION, &class);
+			if (class >> 16 == 0xffff)
+				continue;
+
+			for (bdf = PCI_BDF(bus, devnum, 0);
+					bdf <= PCI_BDF(bus, devnum,
+						PCI_MAX_PCI_FUNCTIONS - 1);
+					bdf += PCI_BDF(0, 0, 1)) {
+				pci_read_config_dword(bdf, PCI_CLASS_REVISION,
+						      &class);
+				class >>= 8;
+
+				if (class != find_class)
+					continue;
+				/*
+				 * Decrement the index. We want to return the
+				 * correct device, so index is 0 for the first
+				 * matching device, 1 for the second, etc.
+				 */
+				if (index) {
+					index--;
+					continue;
+				}
+				/* Return index'th controller. */
+				return bdf;
+			}
+		}
+	}
+
+	return -ENODEV;
+}
+
 pci_dev_t pci_find_device(unsigned int vendor, unsigned int device, int index)
 {
 	struct pci_device_id ids[2] = { {}, {0, 0} };

include/pci.h

@@ -644,8 +644,7 @@ extern int pciauto_config_device(struct pci_controller *hose, pci_dev_t dev);
 
 extern pci_dev_t pci_find_device (unsigned int vendor, unsigned int device, int index);
 extern pci_dev_t pci_find_devices (struct pci_device_id *ids, int index);
-extern pci_dev_t pci_find_class(int wanted_class, int wanted_sub_code,
-				int wanted_prog_if, int index);
+pci_dev_t pci_find_class(unsigned int find_class, int index);
 
 extern int pci_hose_config_device(struct pci_controller *hose,
 				  pci_dev_t dev,