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Date: Thu, 24 Jan 2013 12:38:59 -0800
From: tip-bot for Alexander Gordeev <agordeev@...hat.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, agordeev@...hat.com, hpa@...or.com,
mingo@...nel.org, yinghai@...nel.org, a.p.zijlstra@...llo.nl,
torvalds@...ux-foundation.org, jgarzik@...ox.com,
willy@...ux.intel.com, bhelgaas@...gle.com,
akpm@...ux-foundation.org, suresh.b.siddha@...el.com,
tglx@...utronix.de
Subject: [tip:x86/apic] PCI/MSI:
Enable multiple MSIs with pci_enable_msi_block_auto()
Commit-ID: 08261d87f7d1b6253ab3223756625a5c74532293
Gitweb: http://git.kernel.org/tip/08261d87f7d1b6253ab3223756625a5c74532293
Author: Alexander Gordeev <agordeev@...hat.com>
AuthorDate: Mon, 19 Nov 2012 16:02:10 +0100
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 24 Jan 2013 17:25:13 +0100
PCI/MSI: Enable multiple MSIs with pci_enable_msi_block_auto()
The new function pci_enable_msi_block_auto() tries to allocate
maximum possible number of MSIs up to the number the device
supports. It generalizes a pattern when pci_enable_msi_block()
is contiguously called until it succeeds or fails.
Opposite to pci_enable_msi_block() which takes the number of
MSIs to allocate as a input parameter,
pci_enable_msi_block_auto() could be used by device drivers to
obtain the number of assigned MSIs and the number of MSIs the
device supports.
Signed-off-by: Alexander Gordeev <agordeev@...hat.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Suresh Siddha <suresh.b.siddha@...el.com>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: Matthew Wilcox <willy@...ux.intel.com>
Cc: Jeff Garzik <jgarzik@...ox.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/c3de2419df94a0f95ca1a6f755afc421486455e6.1353324359.git.agordeev@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
Documentation/PCI/MSI-HOWTO.txt | 37 ++++++++++++++++++++++++++++++++-----
drivers/pci/msi.c | 26 ++++++++++++++++++++++++++
include/linux/pci.h | 7 +++++++
3 files changed, 65 insertions(+), 5 deletions(-)
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt
index 53e6fca..a091780 100644
--- a/Documentation/PCI/MSI-HOWTO.txt
+++ b/Documentation/PCI/MSI-HOWTO.txt
@@ -127,15 +127,42 @@ on the number of vectors that can be allocated; pci_enable_msi_block()
returns as soon as it finds any constraint that doesn't allow the
call to succeed.
-4.2.3 pci_disable_msi
+4.2.3 pci_enable_msi_block_auto
+
+int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *count)
+
+This variation on pci_enable_msi() call allows a device driver to request
+the maximum possible number of MSIs. The MSI specification only allows
+interrupts to be allocated in powers of two, up to a maximum of 2^5 (32).
+
+If this function returns a positive number, it indicates that it has
+succeeded and the returned value is the number of allocated interrupts. In
+this case, the function enables MSI on this device and updates dev->irq to
+be the lowest of the new interrupts assigned to it. The other interrupts
+assigned to the device are in the range dev->irq to dev->irq + returned
+value - 1.
+
+If this function returns a negative number, it indicates an error and
+the driver should not attempt to request any more MSI interrupts for
+this device.
+
+If the device driver needs to know the number of interrupts the device
+supports it can pass the pointer count where that number is stored. The
+device driver must decide what action to take if pci_enable_msi_block_auto()
+succeeds, but returns a value less than the number of interrupts supported.
+If the device driver does not need to know the number of interrupts
+supported, it can set the pointer count to NULL.
+
+4.2.4 pci_disable_msi
void pci_disable_msi(struct pci_dev *dev)
This function should be used to undo the effect of pci_enable_msi() or
-pci_enable_msi_block(). Calling it restores dev->irq to the pin-based
-interrupt number and frees the previously allocated message signaled
-interrupt(s). The interrupt may subsequently be assigned to another
-device, so drivers should not cache the value of dev->irq.
+pci_enable_msi_block() or pci_enable_msi_block_auto(). Calling it restores
+dev->irq to the pin-based interrupt number and frees the previously
+allocated message signaled interrupt(s). The interrupt may subsequently be
+assigned to another device, so drivers should not cache the value of
+dev->irq.
Before calling this function, a device driver must always call free_irq()
on any interrupt for which it previously called request_irq().
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 5099636..00cc78c 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -845,6 +845,32 @@ int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)
}
EXPORT_SYMBOL(pci_enable_msi_block);
+int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec)
+{
+ int ret, pos, nvec;
+ u16 msgctl;
+
+ pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
+ if (!pos)
+ return -EINVAL;
+
+ pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl);
+ ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);
+
+ if (maxvec)
+ *maxvec = ret;
+
+ do {
+ nvec = ret;
+ ret = pci_enable_msi_block(dev, nvec);
+ } while (ret > 0);
+
+ if (ret < 0)
+ return ret;
+ return nvec;
+}
+EXPORT_SYMBOL(pci_enable_msi_block_auto);
+
void pci_msi_shutdown(struct pci_dev *dev)
{
struct msi_desc *desc;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 15472d6..6fa4dd2 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1101,6 +1101,12 @@ static inline int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)
return -1;
}
+static inline int
+pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec)
+{
+ return -1;
+}
+
static inline void pci_msi_shutdown(struct pci_dev *dev)
{ }
static inline void pci_disable_msi(struct pci_dev *dev)
@@ -1132,6 +1138,7 @@ static inline int pci_msi_enabled(void)
}
#else
extern int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec);
+extern int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec);
extern void pci_msi_shutdown(struct pci_dev *dev);
extern void pci_disable_msi(struct pci_dev *dev);
extern int pci_msix_table_size(struct pci_dev *dev);
--
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