Skip to content

Commit

Permalink
x86/PCI: Add support for the ALi M1487 (IBC) PIRQ router
Browse files Browse the repository at this point in the history 
The ALi M1487 ISA Bus Controller (IBC), a part of the ALi FinALi 486 
chipset, implements PCI interrupt steering with a PIRQ router[1] in the 
form of four 4-bit mappings, spread across two PCI INTx Routing Table 
Mapping Registers, available in the port I/O space accessible indirectly 
via the index/data register pair at 0x22/0x23, located at indices 0x42 
and 0x43 for the INT1/INT2 and INT3/INT4 lines respectively.

Additionally there is a separate PCI INTx Sensitivity Register at index 
0x44 in the same port I/O space, whose bits 3:0 select the trigger mode 
for INT[4:1] lines respectively[2].  Manufacturer's documentation says 
that this register has to be set consistently with the relevant ELCR 
register[3].  Add a router-specific hook then and use it to handle this 
register.

Accesses to the port I/O space concerned here need to be unlocked by 
writing the value of 0xc5 to the Lock Register at index 0x03 
beforehand[4].  Do so then and then lock access after use for safety.

The IBC is implemented as a peer bridge on the host bus rather than a 
southbridge on PCI and therefore it does not itself appear in the PCI 
configuration space.  It is complemented by the M1489 Cache-Memory PCI 
Controller (CMP) host-to-PCI bridge, so use that device's identification 
for determining the presence of the IBC.

References:

[1] "M1489/M1487: 486 PCI Chip Set", Version 1.2, Acer Laboratories 
    Inc., July 1997, Section 4: "Configuration Registers", pp. 76-77

[2] same, p. 77

[3] same, Section 5: "M1489/M1487 Software Programming Guide", pp. 
    99-100

[4] same, Section 4: "Configuration Registers", p. 37

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2107191702020.9461@angie.orcam.me.uk
  • Loading branch information
Maciej W. Rozycki authored and Thomas Gleixner committed Aug 10, 2021
1 parent fb6a040 commit 1ce849c
Show file tree
Hide file tree
Showing 2 changed files with 153 additions and 2 deletions.
154 changes: 152 additions & 2 deletions arch/x86/pci/irq.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,9 +13,12 @@
#include <linux/dmi.h>
#include <linux/io.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <asm/io_apic.h>
#include <linux/irq.h>
#include <linux/acpi.h>

#include <asm/pc-conf-reg.h>
#include <asm/pci_x86.h>

#define PIRQ_SIGNATURE (('$' << 0) + ('P' << 8) + ('I' << 16) + ('R' << 24))
Expand Down Expand Up @@ -47,6 +50,8 @@ struct irq_router {
int (*get)(struct pci_dev *router, struct pci_dev *dev, int pirq);
int (*set)(struct pci_dev *router, struct pci_dev *dev, int pirq,
int new);
int (*lvl)(struct pci_dev *router, struct pci_dev *dev, int pirq,
int irq);
};

struct irq_router_handler {
Expand Down Expand Up @@ -169,6 +174,139 @@ void elcr_set_level_irq(unsigned int irq)
}
}

/*
* PIRQ routing for the M1487 ISA Bus Controller (IBC) ASIC used
* with the ALi FinALi 486 chipset. The IBC is not decoded in the
* PCI configuration space, so we identify it by the accompanying
* M1489 Cache-Memory PCI Controller (CMP) ASIC.
*
* There are four 4-bit mappings provided, spread across two PCI
* INTx Routing Table Mapping Registers, available in the port I/O
* space accessible indirectly via the index/data register pair at
* 0x22/0x23, located at indices 0x42 and 0x43 for the INT1/INT2
* and INT3/INT4 lines respectively. The INT1/INT3 and INT2/INT4
* lines are mapped in the low and the high 4-bit nibble of the
* corresponding register as follows:
*
* 0000 : Disabled
* 0001 : IRQ9
* 0010 : IRQ3
* 0011 : IRQ10
* 0100 : IRQ4
* 0101 : IRQ5
* 0110 : IRQ7
* 0111 : IRQ6
* 1000 : Reserved
* 1001 : IRQ11
* 1010 : Reserved
* 1011 : IRQ12
* 1100 : Reserved
* 1101 : IRQ14
* 1110 : Reserved
* 1111 : IRQ15
*
* In addition to the usual ELCR register pair there is a separate
* PCI INTx Sensitivity Register at index 0x44 in the same port I/O
* space, whose bits 3:0 select the trigger mode for INT[4:1] lines
* respectively. Any bit set to 1 causes interrupts coming on the
* corresponding line to be passed to ISA as edge-triggered and
* otherwise they are passed as level-triggered. Manufacturer's
* documentation says this register has to be set consistently with
* the relevant ELCR register.
*
* Accesses to the port I/O space concerned here need to be unlocked
* by writing the value of 0xc5 to the Lock Register at index 0x03
* beforehand. Any other value written to said register prevents
* further accesses from reaching the register file, except for the
* Lock Register being written with 0xc5 again.
*
* References:
*
* "M1489/M1487: 486 PCI Chip Set", Version 1.2, Acer Laboratories
* Inc., July 1997
*/

#define PC_CONF_FINALI_LOCK 0x03u
#define PC_CONF_FINALI_PCI_INTX_RT1 0x42u
#define PC_CONF_FINALI_PCI_INTX_RT2 0x43u
#define PC_CONF_FINALI_PCI_INTX_SENS 0x44u

#define PC_CONF_FINALI_LOCK_KEY 0xc5u

static u8 read_pc_conf_nybble(u8 base, u8 index)
{
u8 reg = base + (index >> 1);
u8 x;

x = pc_conf_get(reg);
return index & 1 ? x >> 4 : x & 0xf;
}

static void write_pc_conf_nybble(u8 base, u8 index, u8 val)
{
u8 reg = base + (index >> 1);
u8 x;

x = pc_conf_get(reg);
x = index & 1 ? (x & 0x0f) | (val << 4) : (x & 0xf0) | val;
pc_conf_set(reg, x);
}

static int pirq_finali_get(struct pci_dev *router, struct pci_dev *dev,
int pirq)
{
static const u8 irqmap[16] = {
0, 9, 3, 10, 4, 5, 7, 6, 0, 11, 0, 12, 0, 14, 0, 15
};
unsigned long flags;
u8 x;

raw_spin_lock_irqsave(&pc_conf_lock, flags);
pc_conf_set(PC_CONF_FINALI_LOCK, PC_CONF_FINALI_LOCK_KEY);
x = irqmap[read_pc_conf_nybble(PC_CONF_FINALI_PCI_INTX_RT1, pirq - 1)];
pc_conf_set(PC_CONF_FINALI_LOCK, 0);
raw_spin_unlock_irqrestore(&pc_conf_lock, flags);
return x;
}

static int pirq_finali_set(struct pci_dev *router, struct pci_dev *dev,
int pirq, int irq)
{
static const u8 irqmap[16] = {
0, 0, 0, 2, 4, 5, 7, 6, 0, 1, 3, 9, 11, 0, 13, 15
};
u8 val = irqmap[irq];
unsigned long flags;

if (!val)
return 0;

raw_spin_lock_irqsave(&pc_conf_lock, flags);
pc_conf_set(PC_CONF_FINALI_LOCK, PC_CONF_FINALI_LOCK_KEY);
write_pc_conf_nybble(PC_CONF_FINALI_PCI_INTX_RT1, pirq - 1, val);
pc_conf_set(PC_CONF_FINALI_LOCK, 0);
raw_spin_unlock_irqrestore(&pc_conf_lock, flags);
return 1;
}

static int pirq_finali_lvl(struct pci_dev *router, struct pci_dev *dev,
int pirq, int irq)
{
u8 mask = ~(1u << (pirq - 1));
unsigned long flags;
u8 trig;

elcr_set_level_irq(irq);
raw_spin_lock_irqsave(&pc_conf_lock, flags);
pc_conf_set(PC_CONF_FINALI_LOCK, PC_CONF_FINALI_LOCK_KEY);
trig = pc_conf_get(PC_CONF_FINALI_PCI_INTX_SENS);
trig &= mask;
pc_conf_set(PC_CONF_FINALI_PCI_INTX_SENS, trig);
pc_conf_set(PC_CONF_FINALI_LOCK, 0);
raw_spin_unlock_irqrestore(&pc_conf_lock, flags);
return 1;
}

/*
* Common IRQ routing practice: nibbles in config space,
* offset by some magic constant.
Expand Down Expand Up @@ -745,6 +883,12 @@ static __init int ite_router_probe(struct irq_router *r, struct pci_dev *router,
static __init int ali_router_probe(struct irq_router *r, struct pci_dev *router, u16 device)
{
switch (device) {
case PCI_DEVICE_ID_AL_M1489:
r->name = "FinALi";
r->get = pirq_finali_get;
r->set = pirq_finali_set;
r->lvl = pirq_finali_lvl;
return 1;
case PCI_DEVICE_ID_AL_M1533:
case PCI_DEVICE_ID_AL_M1563:
r->name = "ALI";
Expand Down Expand Up @@ -968,11 +1112,17 @@ static int pcibios_lookup_irq(struct pci_dev *dev, int assign)
} else if (r->get && (irq = r->get(pirq_router_dev, dev, pirq)) && \
((!(pci_probe & PCI_USE_PIRQ_MASK)) || ((1 << irq) & mask))) {
msg = "found";
elcr_set_level_irq(irq);
if (r->lvl)
r->lvl(pirq_router_dev, dev, pirq, irq);
else
elcr_set_level_irq(irq);
} else if (newirq && r->set &&
(dev->class >> 8) != PCI_CLASS_DISPLAY_VGA) {
if (r->set(pirq_router_dev, dev, pirq, newirq)) {
elcr_set_level_irq(newirq);
if (r->lvl)
r->lvl(pirq_router_dev, dev, pirq, newirq);
else
elcr_set_level_irq(newirq);
msg = "assigned";
irq = newirq;
}
Expand Down
1 change: 1 addition & 0 deletions include/linux/pci_ids.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1121,6 +1121,7 @@
#define PCI_DEVICE_ID_3COM_3CR990SVR 0x990a

#define PCI_VENDOR_ID_AL 0x10b9
#define PCI_DEVICE_ID_AL_M1489 0x1489
#define PCI_DEVICE_ID_AL_M1533 0x1533
#define PCI_DEVICE_ID_AL_M1535 0x1535
#define PCI_DEVICE_ID_AL_M1541 0x1541
Expand Down

0 comments on commit 1ce849c

Please sign in to comment.