[PATCH V6] acpi: add support for extended IRQ to PCI link

[PATCH V6] acpi: add support for extended IRQ to PCI link

[Sinan Kaya]

The ACPI compiler uses the extended format when used interrupt numbers
are greater than 256. The extended IRQ numbers use 32 bits for storing
interrupts. The code already supports parsing extended IRQ type but is
limited by 256 due to used data structure type (u8). This patch changes
the interrupt number type to 32 bits and places an upper limit of 1020
as possible interrupt id. 1020 is the maximum interrupt ID that can be
assigned to an ARM SPI interrupt according to ARM architecture.

Additional checks have been placed to return an error when ACPI_MAX_IRQS
is exceeded.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/acpi/pci_link.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
index 7c8408b..5ab83dc 100644
--- a/drivers/acpi/pci_link.c
+++ b/drivers/acpi/pci_link.c
@@ -4,6 +4,7 @@
  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
  *  Copyright (C) 2002       Dominik Brodowski <devel@brodo.de>
+ *  Copyright (c) 2015, The Linux Foundation. All rights reserved.
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  *
@@ -47,6 +48,14 @@ ACPI_MODULE_NAME("pci_link");
 #define ACPI_PCI_LINK_FILE_STATUS	"state"
 #define ACPI_PCI_LINK_MAX_POSSIBLE	16
 
+/*
+ * 1020 is the maximum interrupt ID that can be assigned to
+ * an ARM SPI interrupt according to ARM architecture.
+ */
+#define ACPI_MAX_IRQS		1020
+#define ACPI_MAX_ISA_IRQ	16
+
+
 static int acpi_pci_link_add(struct acpi_device *device,
 			     const struct acpi_device_id *not_used);
 static void acpi_pci_link_remove(struct acpi_device *device);
@@ -67,12 +76,12 @@ static struct acpi_scan_handler pci_link_handler = {
  * later even the link is disable. Instead, we just repick the active irq
  */
 struct acpi_pci_link_irq {
-	u8 active;		/* Current IRQ */
+	u32 active;		/* Current IRQ */
 	u8 triggering;		/* All IRQs */
 	u8 polarity;		/* All IRQs */
 	u8 resource_type;
 	u8 possible_count;
-	u8 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
+	u32 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
 	u8 initialized:1;
 	u8 reserved:7;
 };
@@ -147,6 +156,13 @@ static acpi_status acpi_pci_link_check_possible(struct acpi_resource *resource,
 					       p->interrupts[i]);
 					continue;
 				}
+				if (p->interrupts[i] >= ACPI_MAX_IRQS) {
+					dev_warn(&link->device->dev,
+						"Ignoring IRQ(%d) as it exceeds max(%d)\n",
+						p->interrupts[i],
+						ACPI_MAX_IRQS - 1);
+					continue;
+				}
 				link->irq.possible[i] = p->interrupts[i];
 				link->irq.possible_count++;
 			}
@@ -279,6 +295,12 @@ static int acpi_pci_link_get_current(struct acpi_pci_link *link)
 		result = -ENODEV;
 	}
 
+	if (irq >= ACPI_MAX_IRQS) {
+		dev_err(&link->device->dev,
+			"Ignoring IRQ(%d) as it exceeds max(%d)\n",
+			irq,  ACPI_MAX_IRQS - 1);
+		result = -ENODEV;
+	}
 	link->irq.active = irq;
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Link at IRQ %d \n", link->irq.active));
@@ -437,9 +459,6 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
  * enabled system.
  */
 
-#define ACPI_MAX_IRQS		256
-#define ACPI_MAX_ISA_IRQ	16
-
 #define PIRQ_PENALTY_PCI_AVAILABLE	(0)
 #define PIRQ_PENALTY_PCI_POSSIBLE	(16*16)
 #define PIRQ_PENALTY_PCI_USING		(16*16*16)
-- 
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

Re: [PATCH V6] acpi: add support for extended IRQ to PCI link

[Bjorn Helgaas]

On Wed, Nov 25, 2015 at 01:52:38PM -0500, Sinan Kaya wrote:
> The ACPI compiler uses the extended format when used interrupt numbers
> are greater than 256. The extended IRQ numbers use 32 bits for storing
> interrupts. The code already supports parsing extended IRQ type but is
> limited by 256 due to used data structure type (u8). This patch changes
> the interrupt number type to 32 bits and places an upper limit of 1020
> as possible interrupt id. 1020 is the maximum interrupt ID that can be
> assigned to an ARM SPI interrupt according to ARM architecture.
> 
> Additional checks have been placed to return an error when ACPI_MAX_IRQS
> is exceeded.
> 
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>

I don't think the description is quite accurate -- I think the
extended IRQ descriptor is required for IRQs of *16* and greater, not
IRQs greater than 256.  Here's how I understand it:

  The ACPI IRQ Descriptor contains a 16-bit mask with a bit for each
  IRQ, so it can describe interrupt numbers in the range [0-15].
  Interrupt numbers greater than 15 must be described with an Extended
  IRQ Descriptor, which contains a table of 32-bit interrupt numbers
  and can describe interrupt numbers in the range [0-(2^32-1)].  See
  ACPI 5.0, sections 6.4.2.1 and 6.4.3.6.

> ---
>  drivers/acpi/pci_link.c | 29 ++++++++++++++++++++++++-----
>  1 file changed, 24 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index 7c8408b..5ab83dc 100644
> --- a/drivers/acpi/pci_link.c
> +++ b/drivers/acpi/pci_link.c
> @@ -4,6 +4,7 @@
>   *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
>   *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
>   *  Copyright (C) 2002       Dominik Brodowski <devel@brodo.de>
> + *  Copyright (c) 2015, The Linux Foundation. All rights reserved.
>   *
>   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   *
> @@ -47,6 +48,14 @@ ACPI_MODULE_NAME("pci_link");
>  #define ACPI_PCI_LINK_FILE_STATUS	"state"
>  #define ACPI_PCI_LINK_MAX_POSSIBLE	16
>  
> +/*
> + * 1020 is the maximum interrupt ID that can be assigned to
> + * an ARM SPI interrupt according to ARM architecture.
> + */
> +#define ACPI_MAX_IRQS		1020
> +#define ACPI_MAX_ISA_IRQ	16

ACPI_MAX_IRQS is only used to size the acpi_irq_penalty[] table (and
after your patch, to validate IRQ numbers from ACPI).  But I think the
acpi_irq_penalty[] table is a design we've outgrown.  I *think* we
only care about penalties for IRQs 0-15, so even a 256-entry table is
more than we need.

If we could make acpi_irq_penalty[] a fixed size of 16 entries or
replace it with a linked list, I think we could get rid of
ACPI_MAX_IRQS completely.  Then the validation checks you add below
would be unnecessary and we could handle any interrupt number supplied
from ACPI.

Bjorn

> +
> +
>  static int acpi_pci_link_add(struct acpi_device *device,
>  			     const struct acpi_device_id *not_used);
>  static void acpi_pci_link_remove(struct acpi_device *device);
> @@ -67,12 +76,12 @@ static struct acpi_scan_handler pci_link_handler = {
>   * later even the link is disable. Instead, we just repick the active irq
>   */
>  struct acpi_pci_link_irq {
> -	u8 active;		/* Current IRQ */
> +	u32 active;		/* Current IRQ */
>  	u8 triggering;		/* All IRQs */
>  	u8 polarity;		/* All IRQs */
>  	u8 resource_type;
>  	u8 possible_count;
> -	u8 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
> +	u32 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
>  	u8 initialized:1;
>  	u8 reserved:7;
>  };
> @@ -147,6 +156,13 @@ static acpi_status acpi_pci_link_check_possible(struct acpi_resource *resource,
>  					       p->interrupts[i]);
>  					continue;
>  				}
> +				if (p->interrupts[i] >= ACPI_MAX_IRQS) {
> +					dev_warn(&link->device->dev,
> +						"Ignoring IRQ(%d) as it exceeds max(%d)\n",
> +						p->interrupts[i],
> +						ACPI_MAX_IRQS - 1);
> +					continue;
> +				}
>  				link->irq.possible[i] = p->interrupts[i];
>  				link->irq.possible_count++;
>  			}
> @@ -279,6 +295,12 @@ static int acpi_pci_link_get_current(struct acpi_pci_link *link)
>  		result = -ENODEV;
>  	}
>  
> +	if (irq >= ACPI_MAX_IRQS) {
> +		dev_err(&link->device->dev,
> +			"Ignoring IRQ(%d) as it exceeds max(%d)\n",
> +			irq,  ACPI_MAX_IRQS - 1);
> +		result = -ENODEV;
> +	}
>  	link->irq.active = irq;
>  
>  	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Link at IRQ %d \n", link->irq.active));
> @@ -437,9 +459,6 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
>   * enabled system.
>   */
>  
> -#define ACPI_MAX_IRQS		256
> -#define ACPI_MAX_ISA_IRQ	16
> -
>  #define PIRQ_PENALTY_PCI_AVAILABLE	(0)
>  #define PIRQ_PENALTY_PCI_POSSIBLE	(16*16)
>  #define PIRQ_PENALTY_PCI_USING		(16*16*16)
> -- 
> Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
> 
> --
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Re: [PATCH V6] acpi: add support for extended IRQ to PCI link

[Sinan Kaya]

On 11/30/2015 3:38 PM, Bjorn Helgaas wrote:
>> > Additional checks have been placed to return an error when ACPI_MAX_IRQS
>> > is exceeded.
>> > 
>> > Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> I don't think the description is quite accurate -- I think the
> extended IRQ descriptor is required for IRQs of *16* and greater, not
> IRQs greater than 256.  Here's how I understand it:
> 
>   The ACPI IRQ Descriptor contains a 16-bit mask with a bit for each
>   IRQ, so it can describe interrupt numbers in the range [0-15].
>   Interrupt numbers greater than 15 must be described with an Extended
>   IRQ Descriptor, which contains a table of 32-bit interrupt numbers
>   and can describe interrupt numbers in the range [0-(2^32-1)].  See
>   ACPI 5.0, sections 6.4.2.1 and 6.4.3.6.
> 

You are right. I'm pasting from the spec.

"6.4.2.1 IRQ Descriptor
Type 0, Small Item Name 0x4, Length = 2 or 3
The IRQ data structure indicates that the device uses an interrupt level
and supplies a mask with bits set indicating the levels implemented in
this device. For standard PC-AT implementation there are 15 possible
interrupts so a two-byte field is used. This structure is repeated for
each separate interrupt required"


"6.4.3.6 Extended Interrupt Descriptor
Type 1, Large Item Name 0x9
The Extended Interrupt Descriptor is necessary to describe interrupt
settings and possibilities for systems that support interrupts above 15."

I'll reword correctly. This was a Linux implementation bug not a spec
compliance issue.


-- 
Sinan Kaya
Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
Linux Foundation Collaborative Project