PCI: Add pci_irq_type() to query the allocated interrupt typegrafted

Add a helper that returns PCI_IRQ_MSIX, PCI_IRQ_MSI, or PCI_IRQ_INTX
based on the interrupt type the PCI core selected after
pci_alloc_irq_vectors().

Several drivers already open-code this check against pdev->msix_enabled
and pdev->msi_enabled, or even open code this helper [1].

A common helper avoids the duplication and keeps drivers from accessing
the bitfield directly (see also [2]).

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: John Hubbard <jhubbard@nvidia.com>
Link: https://elixir.bootlin.com/linux/v7.1/source/drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c#L196 [1]
Inspired-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/all/DKKG2QM3YJYB.Z2H2B2UXJ75N@kernel.org/ [2]
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260813165234.620555-5-dakr@kernel.org
[ Add missing pci_irq_type() stub for CONFIG_PCI=n. ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/include/vdso/math64.h b/include/vdso/math64.h
new file mode 100644
index 000000000..22ae212f8
--- /dev/null
+++ b/include/vdso/math64.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_MATH64_H
+#define __VDSO_MATH64_H
+
+static __always_inline u32
+__iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
+{
+	u32 ret = 0;
+
+	while (dividend >= divisor) {
+		/* The following asm() prevents the compiler from
+		   optimising this loop into a modulo operation.  */
+		asm("" : "+rm"(dividend));
+
+		dividend -= divisor;
+		ret++;
+	}
+
+	*remainder = dividend;
+
+	return ret;
+}
+
+#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
+
+#ifndef mul_u64_u32_add_u64_shr
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	return (u64)((((unsigned __int128)a * mul) + b) >> shift);
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#else
+
+#ifndef mul_u64_u32_add_u64_shr
+#ifndef mul_u32_u32
+static inline u64 mul_u32_u32(u32 a, u32 b)
+{
+	return (u64)a * b;
+}
+#define mul_u32_u32 mul_u32_u32
+#endif
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	u32 ah = a >> 32, al = a;
+	bool ovf;
+	u64 ret;
+
+	ovf = __builtin_add_overflow(mul_u32_u32(al, mul), b, &ret);
+	ret >>= shift;
+	if (ovf && shift)
+		ret += 1ULL << (64 - shift);
+	if (ah)
+		ret += mul_u32_u32(ah, mul) << (32 - shift);
+
+	return ret;
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#endif
+
+#endif /* __VDSO_MATH64_H */