/*
* The bits_wide parameter accommodates the limitations of the HW/SW which
* use these bits:
* Legacy PA I/O (GSC/NIO): 5 bits (architected EIM register)
* V-class (EPIC): 6 bits
* N/L/A-class (iosapic): 8 bits
* PCI 2.2 MSI: 16 bits
* Some PCI devices: 32 bits (Symbios SCSI/ATM/HyperFabric)
*
* On the service provider side:
* o PA 1.1 (and PA2.0 narrow mode) 5-bits (width of EIR register)
* o PA 2.0 wide mode 6-bits (per processor)
* o IA64 8-bits (0-256 total)
*
* So a Legacy PA I/O device on a PA 2.0 box can't use all the bits supported
* by the processor...and the N/L-class I/O subsystem supports more bits than
* PA2.0 has. The first case is the problem.
*/
int txn_alloc_irq(unsigned int bits_wide)
{
int irq;
/* never return irq 0 cause that's the interval timer */
for (irq = CPU_IRQ_BASE + 1; irq <= CPU_IRQ_MAX; irq++) {
if (cpu_claim_irq(irq, NULL, NULL) < 0)
continue;
if ((irq - CPU_IRQ_BASE) >= (1 << bits_wide))
continue;
return irq;
}
/* unlikely, but be prepared */
return -1;
}
int txn_alloc_irq(unsigned int bits_wide)
{
int irq;
for (irq = CPU_IRQ_BASE + 1; irq <= CPU_IRQ_MAX; irq++) {
if (cpu_claim_irq(irq, NULL, NULL) < 0)
continue;
if ((irq - CPU_IRQ_BASE) >= (1 << bits_wide))
continue;
return irq;
}
return -1;
}
int txn_claim_irq(int irq)
{
return cpu_claim_irq(irq, NULL, NULL) ? -1 : irq;
}