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PCI MSI: Refactor interrupt masking code
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Since most of the callers already know whether they have an MSI or
an MSI-X capability, split msi_set_mask_bits() into msi_mask_irq()
and msix_mask_irq().  The only callers which don't (mask_msi_irq()
and unmask_msi_irq()) can share code in msi_set_mask_bit().  This then
becomes the only caller of msix_flush_writes(), so we can inline it.
The flushing read can be to any address that belongs to the device,
so we can eliminate the calculation too.

We can also get rid of maskbits_mask from struct msi_desc and simply
recalculate it on the rare occasion that we need it.  The single-bit
'masked' element is replaced by a copy of the 32-bit 'masked' register,
so this patch does not affect the size of msi_desc.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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Matthew Wilcox authored and Jesse Barnes committed Mar 20, 2009
1 parent 264d9ca commit f2440d9
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Showing 2 changed files with 77 additions and 83 deletions.
155 changes: 75 additions & 80 deletions drivers/pci/msi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -105,17 +105,14 @@ static inline __attribute_const__ u32 msi_mask(unsigned x)
return (1 << (1 << x)) - 1;
}

static void msix_flush_writes(struct irq_desc *desc)
static inline __attribute_const__ u32 msi_capable_mask(u16 control)
{
struct msi_desc *entry;
return msi_mask((control >> 1) & 7);
}

entry = get_irq_desc_msi(desc);
BUG_ON(!entry);
if (entry->msi_attrib.is_msix) {
int offset = entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET;
readl(entry->mask_base + offset);
}
static inline __attribute_const__ u32 msi_enabled_mask(u16 control)
{
return msi_mask((control >> 4) & 7);
}

/*
Expand All @@ -127,32 +124,57 @@ static void msix_flush_writes(struct irq_desc *desc)
* Returns 1 if it succeeded in masking the interrupt and 0 if the device
* doesn't support MSI masking.
*/
static int msi_set_mask_bits(struct irq_desc *desc, u32 mask, u32 flag)
static void msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
{
struct msi_desc *entry;
u32 mask_bits = desc->masked;

entry = get_irq_desc_msi(desc);
BUG_ON(!entry);
if (entry->msi_attrib.is_msix) {
int offset = entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET;
writel(flag, entry->mask_base + offset);
readl(entry->mask_base + offset);
} else {
int pos;
u32 mask_bits;
if (!desc->msi_attrib.maskbit)
return;

mask_bits &= ~mask;
mask_bits |= flag;
pci_write_config_dword(desc->dev, desc->mask_pos, mask_bits);
desc->masked = mask_bits;
}

/*
* This internal function does not flush PCI writes to the device.
* All users must ensure that they read from the device before either
* assuming that the device state is up to date, or returning out of this
* file. This saves a few milliseconds when initialising devices with lots
* of MSI-X interrupts.
*/
static void msix_mask_irq(struct msi_desc *desc, u32 flag)
{
u32 mask_bits = desc->masked;
unsigned offset = desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET;
mask_bits &= ~1;
mask_bits |= flag;
writel(mask_bits, desc->mask_base + offset);
desc->masked = mask_bits;
}

if (!entry->msi_attrib.maskbit)
return 0;
static void msi_set_mask_bit(unsigned irq, u32 flag)
{
struct msi_desc *desc = get_irq_msi(irq);

pos = entry->mask_pos;
pci_read_config_dword(entry->dev, pos, &mask_bits);
mask_bits &= ~mask;
mask_bits |= flag & mask;
pci_write_config_dword(entry->dev, pos, mask_bits);
if (desc->msi_attrib.is_msix) {
msix_mask_irq(desc, flag);
readl(desc->mask_base); /* Flush write to device */
} else {
msi_mask_irq(desc, 1, flag);
}
entry->msi_attrib.masked = !!flag;
return 1;
}

void mask_msi_irq(unsigned int irq)
{
msi_set_mask_bit(irq, 1);
}

void unmask_msi_irq(unsigned int irq)
{
msi_set_mask_bit(irq, 0);
}

void read_msi_msg_desc(struct irq_desc *desc, struct msi_msg *msg)
Expand Down Expand Up @@ -230,22 +252,6 @@ void write_msi_msg(unsigned int irq, struct msi_msg *msg)
write_msi_msg_desc(desc, msg);
}

void mask_msi_irq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);

msi_set_mask_bits(desc, 1, 1);
msix_flush_writes(desc);
}

void unmask_msi_irq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);

msi_set_mask_bits(desc, 1, 0);
msix_flush_writes(desc);
}

static int msi_free_irqs(struct pci_dev* dev);

static struct msi_desc *alloc_msi_entry(struct pci_dev *dev)
Expand Down Expand Up @@ -281,13 +287,9 @@ static void __pci_restore_msi_state(struct pci_dev *dev)
pci_intx_for_msi(dev, 0);
msi_set_enable(dev, 0);
write_msi_msg(dev->irq, &entry->msg);
if (entry->msi_attrib.maskbit) {
struct irq_desc *desc = irq_to_desc(dev->irq);
msi_set_mask_bits(desc, entry->msi_attrib.maskbits_mask,
entry->msi_attrib.masked);
}

pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &control);
msi_mask_irq(entry, msi_capable_mask(control), entry->masked);
control &= ~PCI_MSI_FLAGS_QSIZE;
control |= PCI_MSI_FLAGS_ENABLE;
pci_write_config_word(dev, pos + PCI_MSI_FLAGS, control);
Expand All @@ -307,9 +309,8 @@ static void __pci_restore_msix_state(struct pci_dev *dev)
msix_set_enable(dev, 0);

list_for_each_entry(entry, &dev->msi_list, list) {
struct irq_desc *desc = irq_to_desc(entry->irq);
write_msi_msg(entry->irq, &entry->msg);
msi_set_mask_bits(desc, 1, entry->msi_attrib.masked);
msix_mask_irq(entry, entry->masked);
}

BUG_ON(list_empty(&dev->msi_list));
Expand Down Expand Up @@ -342,6 +343,7 @@ static int msi_capability_init(struct pci_dev *dev)
struct msi_desc *entry;
int pos, ret;
u16 control;
unsigned mask;

msi_set_enable(dev, 0); /* Ensure msi is disabled as I set it up */

Expand All @@ -356,21 +358,16 @@ static int msi_capability_init(struct pci_dev *dev)
entry->msi_attrib.is_64 = is_64bit_address(control);
entry->msi_attrib.entry_nr = 0;
entry->msi_attrib.maskbit = is_mask_bit_support(control);
entry->msi_attrib.masked = 1;
entry->msi_attrib.default_irq = dev->irq; /* Save IOAPIC IRQ */
entry->msi_attrib.pos = pos;
if (entry->msi_attrib.maskbit) {
unsigned int base, maskbits, temp;

base = msi_mask_bits_reg(pos, entry->msi_attrib.is_64);
entry->mask_pos = base;
/* All MSIs are unmasked by default, Mask them all */
pci_read_config_dword(dev, base, &maskbits);
temp = msi_mask((control & PCI_MSI_FLAGS_QMASK) >> 1);
maskbits |= temp;
pci_write_config_dword(dev, base, maskbits);
entry->msi_attrib.maskbits_mask = temp;
}

entry->mask_pos = msi_mask_bits_reg(pos, entry->msi_attrib.is_64);
/* All MSIs are unmasked by default, Mask them all */
if (entry->msi_attrib.maskbit)
pci_read_config_dword(dev, entry->mask_pos, &entry->masked);
mask = msi_capable_mask(control);
msi_mask_irq(entry, mask, mask);

list_add_tail(&entry->list, &dev->msi_list);

/* Configure MSI capability structure */
Expand Down Expand Up @@ -435,11 +432,12 @@ static int msix_capability_init(struct pci_dev *dev,
entry->msi_attrib.is_msix = 1;
entry->msi_attrib.is_64 = 1;
entry->msi_attrib.entry_nr = j;
entry->msi_attrib.maskbit = 1;
entry->msi_attrib.masked = 1;
entry->msi_attrib.default_irq = dev->irq;
entry->msi_attrib.pos = pos;
entry->mask_base = base;
entry->masked = readl(base + j * PCI_MSIX_ENTRY_SIZE +
PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
msix_mask_irq(entry, 1);

list_add_tail(&entry->list, &dev->msi_list);
}
Expand Down Expand Up @@ -556,9 +554,11 @@ int pci_enable_msi(struct pci_dev* dev)
}
EXPORT_SYMBOL(pci_enable_msi);

void pci_msi_shutdown(struct pci_dev* dev)
void pci_msi_shutdown(struct pci_dev *dev)
{
struct msi_desc *entry;
struct msi_desc *desc;
u32 mask;
u16 ctrl;

if (!pci_msi_enable || !dev || !dev->msi_enabled)
return;
Expand All @@ -568,18 +568,13 @@ void pci_msi_shutdown(struct pci_dev* dev)
dev->msi_enabled = 0;

BUG_ON(list_empty(&dev->msi_list));
entry = list_entry(dev->msi_list.next, struct msi_desc, list);
/* Return the the pci reset with msi irqs unmasked */
if (entry->msi_attrib.maskbit) {
u32 mask = entry->msi_attrib.maskbits_mask;
struct irq_desc *desc = irq_to_desc(dev->irq);
msi_set_mask_bits(desc, mask, ~mask);
}
if (entry->msi_attrib.is_msix)
return;
desc = list_first_entry(&dev->msi_list, struct msi_desc, list);
pci_read_config_word(dev, desc->msi_attrib.pos + PCI_MSI_FLAGS, &ctrl);
mask = msi_capable_mask(ctrl);
msi_mask_irq(desc, mask, ~mask);

/* Restore dev->irq to its default pin-assertion irq */
dev->irq = entry->msi_attrib.default_irq;
dev->irq = desc->msi_attrib.default_irq;
}

void pci_disable_msi(struct pci_dev* dev)
Expand Down
5 changes: 2 additions & 3 deletions include/linux/msi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -22,14 +22,13 @@ struct msi_desc {
struct {
__u8 is_msix : 1;
__u8 maskbit : 1; /* mask-pending bit supported ? */
__u8 masked : 1;
__u8 is_64 : 1; /* Address size: 0=32bit 1=64bit */
__u8 pos; /* Location of the msi capability */
__u16 entry_nr; /* specific enabled entry */
__u32 maskbits_mask; /* mask bits mask */
unsigned default_irq; /* default pre-assigned irq */
}msi_attrib;
} msi_attrib;

u32 masked; /* mask bits */
unsigned int irq;
struct list_head list;

Expand Down

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