[tip: x86/irq] x86/PCI: Add support for the ALi M1487 (IBC) PIRQ router

From: tip-bot2 for Maciej W. Rozycki
Date: Tue Aug 10 2021 - 17:35:59 EST

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The following commit has been merged into the x86/irq branch of tip:

Commit-ID: 1ce849c755342b236fc6236dfe39dbbf536b64b6
Gitweb: https://git.kernel.org/tip/1ce849c755342b236fc6236dfe39dbbf536b64b6
Author: Maciej W. Rozycki <macro@xxxxxxxxxxx>
AuthorDate: Tue, 20 Jul 2021 05:27:54 +02:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 10 Aug 2021 23:31:43 +02:00

x86/PCI: Add support for the ALi M1487 (IBC) PIRQ router

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@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2107191702020.9461@xxxxxxxxxxxxxxxxx

---
arch/x86/pci/irq.c | 154 ++++++++++++++++++++++++++++++++++++++-
include/linux/pci_ids.h | 1 +-
2 files changed, 153 insertions(+), 2 deletions(-)

diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index d3a73f9..1bccbc4 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -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))
@@ -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 {
@@ -170,6 +175,139 @@ 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.
*/
@@ -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";
@@ -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;
}
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index 4bac183..256fa4d 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -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

Next message: tip-bot2 for Maciej W. Rozycki: "[tip: x86/irq] x86/PCI: Add support for the Intel 82374EB/82374SB (ESC) PIRQ router"
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