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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /arch/alpha/lib/divide.S
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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 ...
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/alpha/lib/divide.S
+ *
+ * (C) 1995 Linus Torvalds
+ *
+ * Alpha division..
+ */
+
+/*
+ * The alpha chip doesn't provide hardware division, so we have to do it
+ * by hand. The compiler expects the functions
+ *
+ * __divqu: 64-bit unsigned long divide
+ * __remqu: 64-bit unsigned long remainder
+ * __divqs/__remqs: signed 64-bit
+ * __divlu/__remlu: unsigned 32-bit
+ * __divls/__remls: signed 32-bit
+ *
+ * These are not normal C functions: instead of the normal
+ * calling sequence, these expect their arguments in registers
+ * $24 and $25, and return the result in $27. Register $28 may
+ * be clobbered (assembly temporary), anything else must be saved.
+ *
+ * In short: painful.
+ *
+ * This is a rather simple bit-at-a-time algorithm: it's very good
+ * at dividing random 64-bit numbers, but the more usual case where
+ * the divisor is small is handled better by the DEC algorithm
+ * using lookup tables. This uses much less memory, though, and is
+ * nicer on the cache.. Besides, I don't know the copyright status
+ * of the DEC code.
+ */
+
+/*
+ * My temporaries:
+ * $0 - current bit
+ * $1 - shifted divisor
+ * $2 - modulus/quotient
+ *
+ * $23 - return address
+ * $24 - dividend
+ * $25 - divisor
+ *
+ * $27 - quotient/modulus
+ * $28 - compare status
+ */
+
+#include <linux/export.h>
+#define halt .long 0
+
+/*
+ * Select function type and registers
+ */
+#define mask $0
+#define divisor $1
+#define compare $28
+#define tmp1 $3
+#define tmp2 $4
+
+#ifdef DIV
+#define DIV_ONLY(x,y...) x,##y
+#define MOD_ONLY(x,y...)
+#define func(x) __div##x
+#define modulus $2
+#define quotient $27
+#define GETSIGN(x) xor $24,$25,x
+#define STACK 48
+#else
+#define DIV_ONLY(x,y...)
+#define MOD_ONLY(x,y...) x,##y
+#define func(x) __rem##x
+#define modulus $27
+#define quotient $2
+#define GETSIGN(x) bis $24,$24,x
+#define STACK 32
+#endif
+
+/*
+ * For 32-bit operations, we need to extend to 64-bit
+ */
+#ifdef INTSIZE
+#define ufunction func(lu)
+#define sfunction func(l)
+#define LONGIFY(x) zapnot x,15,x
+#define SLONGIFY(x) addl x,0,x
+#else
+#define ufunction func(qu)
+#define sfunction func(q)
+#define LONGIFY(x)
+#define SLONGIFY(x)
+#endif
+
+.set noat
+.align 3
+.globl ufunction
+.ent ufunction
+ufunction:
+ subq $30,STACK,$30
+ .frame $30,STACK,$23
+ .prologue 0
+
+7: stq $1, 0($30)
+ bis $25,$25,divisor
+ stq $2, 8($30)
+ bis $24,$24,modulus
+ stq $0,16($30)
+ bis $31,$31,quotient
+ LONGIFY(divisor)
+ stq tmp1,24($30)
+ LONGIFY(modulus)
+ bis $31,1,mask
+ DIV_ONLY(stq tmp2,32($30))
+ beq divisor, 9f /* div by zero */
+
+#ifdef INTSIZE
+ /*
+ * shift divisor left, using 3-bit shifts for
+ * 32-bit divides as we can't overflow. Three-bit
+ * shifts will result in looping three times less
+ * here, but can result in two loops more later.
+ * Thus using a large shift isn't worth it (and
+ * s8add pairs better than a sll..)
+ */
+1: cmpult divisor,modulus,compare
+ s8addq divisor,$31,divisor
+ s8addq mask,$31,mask
+ bne compare,1b
+#else
+1: cmpult divisor,modulus,compare
+ blt divisor, 2f
+ addq divisor,divisor,divisor
+ addq mask,mask,mask
+ bne compare,1b
+ unop
+#endif
+
+ /* ok, start to go right again.. */
+2: DIV_ONLY(addq quotient,mask,tmp2)
+ srl mask,1,mask
+ cmpule divisor,modulus,compare
+ subq modulus,divisor,tmp1
+ DIV_ONLY(cmovne compare,tmp2,quotient)
+ srl divisor,1,divisor
+ cmovne compare,tmp1,modulus
+ bne mask,2b
+
+9: ldq $1, 0($30)
+ ldq $2, 8($30)
+ ldq $0,16($30)
+ ldq tmp1,24($30)
+ DIV_ONLY(ldq tmp2,32($30))
+ addq $30,STACK,$30
+ ret $31,($23),1
+ .end ufunction
+EXPORT_SYMBOL(ufunction)
+
+/*
+ * Uhh.. Ugly signed division. I'd rather not have it at all, but
+ * it's needed in some circumstances. There are different ways to
+ * handle this, really. This does:
+ * -a / b = a / -b = -(a / b)
+ * -a % b = -(a % b)
+ * a % -b = a % b
+ * which is probably not the best solution, but at least should
+ * have the property that (x/y)*y + (x%y) = x.
+ */
+.align 3
+.globl sfunction
+.ent sfunction
+sfunction:
+ subq $30,STACK,$30
+ .frame $30,STACK,$23
+ .prologue 0
+ bis $24,$25,$28
+ SLONGIFY($28)
+ bge $28,7b
+ stq $24,0($30)
+ subq $31,$24,$28
+ stq $25,8($30)
+ cmovlt $24,$28,$24 /* abs($24) */
+ stq $23,16($30)
+ subq $31,$25,$28
+ stq tmp1,24($30)
+ cmovlt $25,$28,$25 /* abs($25) */
+ unop
+ bsr $23,ufunction
+ ldq $24,0($30)
+ ldq $25,8($30)
+ GETSIGN($28)
+ subq $31,$27,tmp1
+ SLONGIFY($28)
+ ldq $23,16($30)
+ cmovlt $28,tmp1,$27
+ ldq tmp1,24($30)
+ addq $30,STACK,$30
+ ret $31,($23),1
+ .end sfunction
+EXPORT_SYMBOL(sfunction)