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x86/pci: Clean up open-coded PCIBIOS return code mangling

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Per PCI Firmware spec r3.3, sec 2.5.2, 2.6.2, and 2.7, the return code for
these PCI BIOS interfaces is in 8 bits of the EAX register.  Previously it
was extracted by open-coded masks and shifting.

Name the return code bits with a #define and add pcibios_get_return_code()
to extract the return code to improve code readability. In addition,
replace zero test with PCIBIOS_SUCCESSFUL.

No functional changes intended.

Link: https://lore.kernel.org/r/20231124085924.13830-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Ilpo Järvinen 2023-11-24 10:59:24 +02:00 committed by Bjorn Helgaas
parent 420ac76610
commit 0d481ff35c
1 changed files with 21 additions and 7 deletions
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28
arch/x86/pci/pcbios.c
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@ -3,6 +3,8 @@
* BIOS32 and PCI BIOS handling.
*/
#include <linux/bits.h>
#include <linux/bitfield.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/slab.h>
@ -29,8 +31,19 @@
#define PCIBIOS_HW_TYPE1_SPEC 0x10
#define PCIBIOS_HW_TYPE2_SPEC 0x20
/*
* Returned in EAX:
* - AH: return code
*/
#define PCIBIOS_RETURN_CODE GENMASK(15, 8)
int pcibios_enabled;
static u8 pcibios_get_return_code(u32 eax)
{
return FIELD_GET(PCIBIOS_RETURN_CODE, eax);
}
/* According to the BIOS specification at:
* http://members.datafast.net.au/dft0802/specs/bios21.pdf, we could
* restrict the x zone to some pages and make it ro. But this may be
@ -154,7 +167,7 @@ static int __init check_pcibios(void)
: "memory");
local_irq_restore(flags);
status = (eax >> 8) & 0xff;
status = pcibios_get_return_code(eax);
hw_mech = eax & 0xff;
major_ver = (ebx >> 8) & 0xff;
minor_ver = ebx & 0xff;
@ -227,7 +240,7 @@ static int pci_bios_read(unsigned int seg, unsigned int bus,
raw_spin_unlock_irqrestore(&pci_config_lock, flags);
return (int)((result & 0xff00) >> 8);
return pcibios_get_return_code(result);
}
static int pci_bios_write(unsigned int seg, unsigned int bus,
@ -269,7 +282,7 @@ static int pci_bios_write(unsigned int seg, unsigned int bus,
raw_spin_unlock_irqrestore(&pci_config_lock, flags);
return (int)((result & 0xff00) >> 8);
return pcibios_get_return_code(result);
}
@ -385,9 +398,10 @@ struct irq_routing_table * pcibios_get_irq_routing_table(void)
"m" (opt)
: "memory");
DBG("OK ret=%d, size=%d, map=%x\n", ret, opt.size, map);
if (ret & 0xff00)
printk(KERN_ERR "PCI: Error %02x when fetching IRQ routing table.\n", (ret >> 8) & 0xff);
else if (opt.size) {
ret = pcibios_get_return_code(ret);
if (ret) {
printk(KERN_ERR "PCI: Error %02x when fetching IRQ routing table.\n", ret);
} else if (opt.size) {
rt = kmalloc(sizeof(struct irq_routing_table) + opt.size, GFP_KERNEL);
if (rt) {
memset(rt, 0, sizeof(struct irq_routing_table));
@ -415,7 +429,7 @@ int pcibios_set_irq_routing(struct pci_dev *dev, int pin, int irq)
"b" ((dev->bus->number << 8) | dev->devfn),
"c" ((irq << 8) | (pin + 10)),
"S" (&pci_indirect));
return !(ret & 0xff00);
return pcibios_get_return_code(ret) == PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL(pcibios_set_irq_routing);