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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
| commit | 4352b8aee98005853aa63f57d6377282de17a33f (patch) | |
| tree | 27614d7a9ef05c32d089004e104364ce42324837 /include/asm-generic/div64.h | |
| download | linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip | |
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni:
"A new driver this cycle, for the AMD AXI I3C controller.
There are also new features such as IBI wakeup support, SETAASA device
discovery and ACPI support for the the DAA methods, meaning we can now
communicate with the SPD devices on DDR5 modules.
New driver:
- AMD AXI I3C master controller
Subsystem:
- I3C Common Command Code (CCC) handling improvements, especially
around GET CCCs
- SETAASA device discovery support
- ACPI support for all existing DAA methods like SETDASA, SETNEWDA as
well as I2C devices on I3C bus
- IBI-based wakeup support
Drivers:
- dw: SETAASA support
- mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C
controller support, PIO queue management support for HCI v1.2
- renesas: improve suspend to RAM support, add runtime PM support"
* tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits)
i3c: dw: reduce do_daa time if there's no client
i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller
i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2
i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode
i3c: dw: rename "pclk" to "apb" to match dt-binding
i3c: dw: make struct dw_i3c_cmd smaller
i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding
i3c: renesas: Don't register devices when ENTDAA times out
i3c: master: dw-i3c-master: fix OD timing for first broadcast
i3c: mipi-i3c-hci: Advertise IBI wakeup capability
i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()
i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI
i3c: master: Reject IBI requests from non-IBI-capable devices
i3c: master: Add helper to query bus wakeup requirements
i3c: master: Report wakeup events for IBIs
i3c: master: Support IBI-based wakeup capability
i3c: master: Fix potential UAF in i3c_device_match()
i3c: master: Fix potential UAF in i3c_device_uevent()
i3c: Make dev->desc locking assumptions explicit
i3c: master: Fix use-after-free of master->this
...
Diffstat (limited to 'include/asm-generic/div64.h')
| -rw-r--r-- | include/asm-generic/div64.h | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/include/asm-generic/div64.h b/include/asm-generic/div64.h new file mode 100644 index 000000000..25e7b4b58 --- /dev/null +++ b/include/asm-generic/div64.h @@ -0,0 +1,210 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_GENERIC_DIV64_H +#define _ASM_GENERIC_DIV64_H +/* + * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com> + * Based on former asm-ppc/div64.h and asm-m68knommu/div64.h + * + * Optimization for constant divisors on 32-bit machines: + * Copyright (C) 2006-2015 Nicolas Pitre + * + * The semantics of do_div() is, in C++ notation, observing that the name + * is a function-like macro and the n parameter has the semantics of a C++ + * reference: + * + * uint32_t do_div(uint64_t &n, uint32_t base) + * { + * uint32_t remainder = n % base; + * n = n / base; + * return remainder; + * } + * + * NOTE: macro parameter n is evaluated multiple times, + * beware of side effects! + */ + +#include <linux/types.h> +#include <linux/compiler.h> + +#if BITS_PER_LONG == 64 + +/** + * do_div - returns 2 values: calculate remainder and update new dividend + * @n: uint64_t dividend (will be updated) + * @base: uint32_t divisor + * + * Summary: + * ``uint32_t remainder = n % base;`` + * ``n = n / base;`` + * + * Return: (uint32_t)remainder + * + * NOTE: macro parameter @n is evaluated multiple times, + * beware of side effects! + */ +# define do_div(n,base) ({ \ + uint32_t __base = (base); \ + uint32_t __rem; \ + __rem = ((uint64_t)(n)) % __base; \ + (n) = ((uint64_t)(n)) / __base; \ + __rem; \ + }) + +#elif BITS_PER_LONG == 32 + +#include <linux/log2.h> + +/* + * If the divisor happens to be constant, we determine the appropriate + * inverse at compile time to turn the division into a few inline + * multiplications which ought to be much faster. + * + * (It is unfortunate that gcc doesn't perform all this internally.) + */ + +#define __div64_const32(n, ___b) \ +({ \ + /* \ + * Multiplication by reciprocal of b: n / b = n * (p / b) / p \ + * \ + * We rely on the fact that most of this code gets optimized \ + * away at compile time due to constant propagation and only \ + * a few multiplication instructions should remain. \ + * Hence this monstrous macro (static inline doesn't always \ + * do the trick here). \ + */ \ + uint64_t ___res, ___x, ___t, ___m, ___n = (n); \ + uint32_t ___p; \ + bool ___bias = false; \ + \ + /* determine MSB of b */ \ + ___p = 1 << ilog2(___b); \ + \ + /* compute m = ((p << 64) + b - 1) / b */ \ + ___m = (~0ULL / ___b) * ___p; \ + ___m += (((~0ULL % ___b + 1) * ___p) + ___b - 1) / ___b; \ + \ + /* one less than the dividend with highest result */ \ + ___x = ~0ULL / ___b * ___b - 1; \ + \ + /* test our ___m with res = m * x / (p << 64) */ \ + ___res = (___m & 0xffffffff) * (___x & 0xffffffff); \ + ___t = (___m & 0xffffffff) * (___x >> 32) + (___res >> 32); \ + ___res = (___m >> 32) * (___x >> 32) + (___t >> 32); \ + ___t = (___m >> 32) * (___x & 0xffffffff) + (___t & 0xffffffff);\ + ___res = (___res + (___t >> 32)) / ___p; \ + \ + /* Now validate what we've got. */ \ + if (___res != ___x / ___b) { \ + /* \ + * We can't get away without a bias to compensate \ + * for bit truncation errors. To avoid it we'd need an \ + * additional bit to represent m which would overflow \ + * a 64-bit variable. \ + * \ + * Instead we do m = p / b and n / b = (n * m + m) / p. \ + */ \ + ___bias = true; \ + /* Compute m = (p << 64) / b */ \ + ___m = (~0ULL / ___b) * ___p; \ + ___m += ((~0ULL % ___b + 1) * ___p) / ___b; \ + } \ + \ + /* Reduce m / p to help avoid overflow handling later. */ \ + ___p /= (___m & -___m); \ + ___m /= (___m & -___m); \ + \ + /* \ + * Perform (m_bias + m * n) / (1 << 64). \ + * From now on there will be actual runtime code generated. \ + */ \ + ___res = __arch_xprod_64(___m, ___n, ___bias); \ + \ + ___res /= ___p; \ +}) + +#ifndef __arch_xprod_64 +/* + * Default C implementation for __arch_xprod_64() + * + * Prototype: uint64_t __arch_xprod_64(const uint64_t m, uint64_t n, bool bias) + * Semantic: retval = ((bias ? m : 0) + m * n) >> 64 + * + * The product is a 128-bit value, scaled down to 64 bits. + * Hoping for compile-time optimization of conditional code. + * Architectures may provide their own optimized assembly implementation. + */ +#ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE +static __always_inline +#else +static inline +#endif +uint64_t __arch_xprod_64(const uint64_t m, uint64_t n, bool bias) +{ + uint32_t m_lo = m; + uint32_t m_hi = m >> 32; + uint32_t n_lo = n; + uint32_t n_hi = n >> 32; + uint64_t x, y; + + /* Determine if overflow handling can be dispensed with. */ + bool no_ovf = __builtin_constant_p(m) && + ((m >> 32) + (m & 0xffffffff) < 0x100000000); + + if (no_ovf) { + x = (uint64_t)m_lo * n_lo + (bias ? m : 0); + x >>= 32; + x += (uint64_t)m_lo * n_hi; + x += (uint64_t)m_hi * n_lo; + x >>= 32; + x += (uint64_t)m_hi * n_hi; + } else { + x = (uint64_t)m_lo * n_lo + (bias ? m_lo : 0); + y = (uint64_t)m_lo * n_hi + (uint32_t)(x >> 32) + (bias ? m_hi : 0); + x = (uint64_t)m_hi * n_hi + (uint32_t)(y >> 32); + y = (uint64_t)m_hi * n_lo + (uint32_t)y; + x += (uint32_t)(y >> 32); + } + + return x; +} +#endif + +#ifndef __div64_32 +extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor); +#endif + +/* The unnecessary pointer compare is there + * to check for type safety (n must be 64bit) + */ +# define do_div(n,base) ({ \ + uint32_t __base = (base); \ + uint32_t __rem; \ + (void)(((typeof((n)) *)0) == ((uint64_t *)0)); \ + if (__builtin_constant_p(__base) && \ + is_power_of_2(__base)) { \ + __rem = (n) & (__base - 1); \ + (n) >>= ilog2(__base); \ + } else if (__builtin_constant_p(__base) && \ + __base != 0) { \ + uint32_t __res_lo, __n_lo = (n); \ + (n) = __div64_const32(n, __base); \ + /* the remainder can be computed with 32-bit regs */ \ + __res_lo = (n); \ + __rem = __n_lo - __res_lo * __base; \ + } else if (likely(((n) >> 32) == 0)) { \ + __rem = (uint32_t)(n) % __base; \ + (n) = (uint32_t)(n) / __base; \ + } else { \ + __rem = __div64_32(&(n), __base); \ + } \ + __rem; \ + }) + +#else /* BITS_PER_LONG == ?? */ + +# error do_div() does not yet support the C64 + +#endif /* BITS_PER_LONG */ + +#endif /* _ASM_GENERIC_DIV64_H */ |
