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-rw-r--r--arch/arm/include/asm/div64.h111
1 files changed, 111 insertions, 0 deletions
diff --git a/arch/arm/include/asm/div64.h b/arch/arm/include/asm/div64.h
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+++ b/arch/arm/include/asm/div64.h
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+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_ARM_DIV64
+#define __ASM_ARM_DIV64
+
+#include <linux/types.h>
+#include <asm/compiler.h>
+
+/*
+ * The semantics of __div64_32() are:
+ *
+ * uint32_t __div64_32(uint64_t *n, uint32_t base)
+ * {
+ * uint32_t remainder = *n % base;
+ * *n = *n / base;
+ * return remainder;
+ * }
+ *
+ * In other words, a 64-bit dividend with a 32-bit divisor producing
+ * a 64-bit result and a 32-bit remainder. To accomplish this optimally
+ * we override the generic version in lib/div64.c to call our __do_div64
+ * assembly implementation with completely non standard calling convention
+ * for arguments and results (beware).
+ */
+static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
+{
+ register unsigned int __base asm("r4") = base;
+ register unsigned long long __n asm("r0") = *n;
+ register unsigned long long __res asm("r2");
+ unsigned int __rem;
+ asm( __asmeq("%0", "r0")
+ __asmeq("%1", "r2")
+ __asmeq("%2", "r4")
+ "bl __do_div64"
+ : "+r" (__n), "=r" (__res)
+ : "r" (__base)
+ : "ip", "lr", "cc");
+ __rem = __n >> 32;
+ *n = __res;
+ return __rem;
+}
+#define __div64_32 __div64_32
+
+#if !defined(CONFIG_AEABI)
+
+/*
+ * In OABI configurations, some uses of the do_div function
+ * cause gcc to run out of registers. To work around that,
+ * we can force the use of the out-of-line version for
+ * configurations that build a OABI kernel.
+ */
+#define do_div(n, base) __div64_32(&(n), base)
+
+#else
+
+static inline uint64_t __arch_xprod_64(uint64_t m, uint64_t n, bool bias)
+{
+ unsigned long long res;
+ register unsigned int tmp asm("ip") = 0;
+
+ if (!bias) {
+ asm ( "umull %Q0, %R0, %Q1, %Q2\n\t"
+ "mov %Q0, #0"
+ : "=&r" (res)
+ : "r" (m), "r" (n)
+ : "cc");
+ } else if (!(m & ((1ULL << 63) | (1ULL << 31)))) {
+ res = m;
+ asm ( "umlal %Q0, %R0, %Q1, %Q2\n\t"
+ "mov %Q0, #0"
+ : "+&r" (res)
+ : "r" (m), "r" (n)
+ : "cc");
+ } else {
+ asm ( "umull %Q0, %R0, %Q2, %Q3\n\t"
+ "cmn %Q0, %Q2\n\t"
+ "adcs %R0, %R0, %R2\n\t"
+ "adc %Q0, %1, #0"
+ : "=&r" (res), "+&r" (tmp)
+ : "r" (m), "r" (n)
+ : "cc");
+ }
+
+ if (!(m & ((1ULL << 63) | (1ULL << 31)))) {
+ asm ( "umlal %R0, %Q0, %R1, %Q2\n\t"
+ "umlal %R0, %Q0, %Q1, %R2\n\t"
+ "mov %R0, #0\n\t"
+ "umlal %Q0, %R0, %R1, %R2"
+ : "+&r" (res)
+ : "r" (m), "r" (n)
+ : "cc");
+ } else {
+ asm ( "umlal %R0, %Q0, %R2, %Q3\n\t"
+ "umlal %R0, %1, %Q2, %R3\n\t"
+ "mov %R0, #0\n\t"
+ "adds %Q0, %1, %Q0\n\t"
+ "adc %R0, %R0, #0\n\t"
+ "umlal %Q0, %R0, %R2, %R3"
+ : "+&r" (res), "+&r" (tmp)
+ : "r" (m), "r" (n)
+ : "cc");
+ }
+
+ return res;
+}
+#define __arch_xprod_64 __arch_xprod_64
+
+#include <asm-generic/div64.h>
+
+#endif
+
+#endif