x86/PCI: Simplify pci_bios_{read,write}

There is some repetitive code in the switch/case statements in
pci_bios_read() and pci_bios_write().  Factor out the BIOS function
IDs and the result widths to simplify the code.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/pci/pcbios.c

@@ -180,6 +180,7 @@ static int pci_bios_read(unsigned int seg, unsigned int bus,
 	unsigned long result = 0;
 	unsigned long flags;
 	unsigned long bx = (bus << 8) | devfn;
+	u16 number = 0, mask = 0;
 
 	WARN_ON(seg);
 	if (!value || (bus > 255) || (devfn > 255) || (reg > 255))
@@ -189,53 +190,35 @@ static int pci_bios_read(unsigned int seg, unsigned int bus,
 
 	switch (len) {
 	case 1:
-		__asm__("lcall *(%%esi); cld\n\t"
-			"jc 1f\n\t"
-			"xor %%ah, %%ah\n"
-			"1:"
-			: "=c" (*value),
-			  "=a" (result)
-			: "1" (PCIBIOS_READ_CONFIG_BYTE),
-			  "b" (bx),
-			  "D" ((long)reg),
-			  "S" (&pci_indirect));
-		/*
-		 * Zero-extend the result beyond 8 bits, do not trust the
-		 * BIOS having done it:
-		 */
-		*value &= 0xff;
+		number = PCIBIOS_READ_CONFIG_BYTE;
+		mask = 0xff;
 		break;
 	case 2:
-		__asm__("lcall *(%%esi); cld\n\t"
-			"jc 1f\n\t"
-			"xor %%ah, %%ah\n"
-			"1:"
-			: "=c" (*value),
-			  "=a" (result)
-			: "1" (PCIBIOS_READ_CONFIG_WORD),
-			  "b" (bx),
-			  "D" ((long)reg),
-			  "S" (&pci_indirect));
-		/*
-		 * Zero-extend the result beyond 16 bits, do not trust the
-		 * BIOS having done it:
-		 */
-		*value &= 0xffff;
+		number = PCIBIOS_READ_CONFIG_WORD;
+		mask = 0xffff;
 		break;
 	case 4:
-		__asm__("lcall *(%%esi); cld\n\t"
-			"jc 1f\n\t"
-			"xor %%ah, %%ah\n"
-			"1:"
-			: "=c" (*value),
-			  "=a" (result)
-			: "1" (PCIBIOS_READ_CONFIG_DWORD),
-			  "b" (bx),
-			  "D" ((long)reg),
-			  "S" (&pci_indirect));
+		number = PCIBIOS_READ_CONFIG_DWORD;
 		break;
 	}
 
+	__asm__("lcall *(%%esi); cld\n\t"
+		"jc 1f\n\t"
+		"xor %%ah, %%ah\n"
+		"1:"
+		: "=c" (*value),
+		  "=a" (result)
+		: "1" (number),
+		  "b" (bx),
+		  "D" ((long)reg),
+		  "S" (&pci_indirect));
+	/*
+	 * Zero-extend the result beyond 8 or 16 bits, do not trust the
+	 * BIOS having done it:
+	 */
+	if (mask)
+		*value &= mask;
+
 	raw_spin_unlock_irqrestore(&pci_config_lock, flags);
 
 	return (int)((result & 0xff00) >> 8);
@@ -247,6 +230,7 @@ static int pci_bios_write(unsigned int seg, unsigned int bus,
 	unsigned long result = 0;
 	unsigned long flags;
 	unsigned long bx = (bus << 8) | devfn;
+	u16 number = 0;
 
 	WARN_ON(seg);
 	if ((bus > 255) || (devfn > 255) || (reg > 255)) 
@@ -256,43 +240,27 @@ static int pci_bios_write(unsigned int seg, unsigned int bus,
 
 	switch (len) {
 	case 1:
-		__asm__("lcall *(%%esi); cld\n\t"
-			"jc 1f\n\t"
-			"xor %%ah, %%ah\n"
-			"1:"
-			: "=a" (result)
-			: "0" (PCIBIOS_WRITE_CONFIG_BYTE),
-			  "c" (value),
-			  "b" (bx),
-			  "D" ((long)reg),
-			  "S" (&pci_indirect));
+		number = PCIBIOS_WRITE_CONFIG_BYTE;
 		break;
 	case 2:
-		__asm__("lcall *(%%esi); cld\n\t"
-			"jc 1f\n\t"
-			"xor %%ah, %%ah\n"
-			"1:"
-			: "=a" (result)
-			: "0" (PCIBIOS_WRITE_CONFIG_WORD),
-			  "c" (value),
-			  "b" (bx),
-			  "D" ((long)reg),
-			  "S" (&pci_indirect));
+		number = PCIBIOS_WRITE_CONFIG_WORD;
 		break;
 	case 4:
-		__asm__("lcall *(%%esi); cld\n\t"
-			"jc 1f\n\t"
-			"xor %%ah, %%ah\n"
-			"1:"
-			: "=a" (result)
-			: "0" (PCIBIOS_WRITE_CONFIG_DWORD),
-			  "c" (value),
-			  "b" (bx),
-			  "D" ((long)reg),
-			  "S" (&pci_indirect));
+		number = PCIBIOS_WRITE_CONFIG_DWORD;
 		break;
 	}
 
+	__asm__("lcall *(%%esi); cld\n\t"
+		"jc 1f\n\t"
+		"xor %%ah, %%ah\n"
+		"1:"
+		: "=a" (result)
+		: "0" (number),
+		  "c" (value),
+		  "b" (bx),
+		  "D" ((long)reg),
+		  "S" (&pci_indirect));
+
 	raw_spin_unlock_irqrestore(&pci_config_lock, flags);
 
 	return (int)((result & 0xff00) >> 8);