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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 /lib/atomic64.c
downloadlinux-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 'lib/atomic64.c')
-rw-r--r--lib/atomic64.c207
1 files changed, 207 insertions, 0 deletions
diff --git a/lib/atomic64.c b/lib/atomic64.c
new file mode 100644
index 000000000..1a72bba36
--- /dev/null
+++ b/lib/atomic64.c
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Generic implementation of 64-bit atomics using spinlocks,
+ * useful on processors that don't have 64-bit atomic instructions.
+ *
+ * Copyright © 2009 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ */
+#include <linux/types.h>
+#include <linux/cache.h>
+#include <linux/spinlock.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/atomic.h>
+
+/*
+ * We use a hashed array of spinlocks to provide exclusive access
+ * to each atomic64_t variable. Since this is expected to used on
+ * systems with small numbers of CPUs (<= 4 or so), we use a
+ * relatively small array of 16 spinlocks to avoid wasting too much
+ * memory on the spinlock array.
+ */
+#define NR_LOCKS 16
+
+/*
+ * Ensure each lock is in a separate cacheline.
+ */
+static union {
+ arch_spinlock_t lock;
+ char pad[L1_CACHE_BYTES];
+} atomic64_lock[NR_LOCKS] __cacheline_aligned_in_smp = {
+ [0 ... (NR_LOCKS - 1)] = {
+ .lock = __ARCH_SPIN_LOCK_UNLOCKED,
+ },
+};
+
+static inline arch_spinlock_t *lock_addr(const atomic64_t *v)
+{
+ unsigned long addr = (unsigned long) v;
+
+ addr >>= L1_CACHE_SHIFT;
+ addr ^= (addr >> 8) ^ (addr >> 16);
+ return &atomic64_lock[addr & (NR_LOCKS - 1)].lock;
+}
+
+s64 generic_atomic64_read(const atomic64_t *v)
+{
+ unsigned long flags;
+ arch_spinlock_t *lock = lock_addr(v);
+ s64 val;
+
+ local_irq_save(flags);
+ arch_spin_lock(lock);
+ val = v->counter;
+ arch_spin_unlock(lock);
+ local_irq_restore(flags);
+ return val;
+}
+EXPORT_SYMBOL(generic_atomic64_read);
+
+void generic_atomic64_set(atomic64_t *v, s64 i)
+{
+ unsigned long flags;
+ arch_spinlock_t *lock = lock_addr(v);
+
+ local_irq_save(flags);
+ arch_spin_lock(lock);
+ v->counter = i;
+ arch_spin_unlock(lock);
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(generic_atomic64_set);
+
+#define ATOMIC64_OP(op, c_op) \
+void generic_atomic64_##op(s64 a, atomic64_t *v) \
+{ \
+ unsigned long flags; \
+ arch_spinlock_t *lock = lock_addr(v); \
+ \
+ local_irq_save(flags); \
+ arch_spin_lock(lock); \
+ v->counter c_op a; \
+ arch_spin_unlock(lock); \
+ local_irq_restore(flags); \
+} \
+EXPORT_SYMBOL(generic_atomic64_##op);
+
+#define ATOMIC64_OP_RETURN(op, c_op) \
+s64 generic_atomic64_##op##_return(s64 a, atomic64_t *v) \
+{ \
+ unsigned long flags; \
+ arch_spinlock_t *lock = lock_addr(v); \
+ s64 val; \
+ \
+ local_irq_save(flags); \
+ arch_spin_lock(lock); \
+ val = (v->counter c_op a); \
+ arch_spin_unlock(lock); \
+ local_irq_restore(flags); \
+ return val; \
+} \
+EXPORT_SYMBOL(generic_atomic64_##op##_return);
+
+#define ATOMIC64_FETCH_OP(op, c_op) \
+s64 generic_atomic64_fetch_##op(s64 a, atomic64_t *v) \
+{ \
+ unsigned long flags; \
+ arch_spinlock_t *lock = lock_addr(v); \
+ s64 val; \
+ \
+ local_irq_save(flags); \
+ arch_spin_lock(lock); \
+ val = v->counter; \
+ v->counter c_op a; \
+ arch_spin_unlock(lock); \
+ local_irq_restore(flags); \
+ return val; \
+} \
+EXPORT_SYMBOL(generic_atomic64_fetch_##op);
+
+#define ATOMIC64_OPS(op, c_op) \
+ ATOMIC64_OP(op, c_op) \
+ ATOMIC64_OP_RETURN(op, c_op) \
+ ATOMIC64_FETCH_OP(op, c_op)
+
+ATOMIC64_OPS(add, +=)
+ATOMIC64_OPS(sub, -=)
+
+#undef ATOMIC64_OPS
+#define ATOMIC64_OPS(op, c_op) \
+ ATOMIC64_OP(op, c_op) \
+ ATOMIC64_FETCH_OP(op, c_op)
+
+ATOMIC64_OPS(and, &=)
+ATOMIC64_OPS(or, |=)
+ATOMIC64_OPS(xor, ^=)
+
+#undef ATOMIC64_OPS
+#undef ATOMIC64_FETCH_OP
+#undef ATOMIC64_OP
+
+s64 generic_atomic64_dec_if_positive(atomic64_t *v)
+{
+ unsigned long flags;
+ arch_spinlock_t *lock = lock_addr(v);
+ s64 val;
+
+ local_irq_save(flags);
+ arch_spin_lock(lock);
+ val = v->counter - 1;
+ if (val >= 0)
+ v->counter = val;
+ arch_spin_unlock(lock);
+ local_irq_restore(flags);
+ return val;
+}
+EXPORT_SYMBOL(generic_atomic64_dec_if_positive);
+
+s64 generic_atomic64_cmpxchg(atomic64_t *v, s64 o, s64 n)
+{
+ unsigned long flags;
+ arch_spinlock_t *lock = lock_addr(v);
+ s64 val;
+
+ local_irq_save(flags);
+ arch_spin_lock(lock);
+ val = v->counter;
+ if (val == o)
+ v->counter = n;
+ arch_spin_unlock(lock);
+ local_irq_restore(flags);
+ return val;
+}
+EXPORT_SYMBOL(generic_atomic64_cmpxchg);
+
+s64 generic_atomic64_xchg(atomic64_t *v, s64 new)
+{
+ unsigned long flags;
+ arch_spinlock_t *lock = lock_addr(v);
+ s64 val;
+
+ local_irq_save(flags);
+ arch_spin_lock(lock);
+ val = v->counter;
+ v->counter = new;
+ arch_spin_unlock(lock);
+ local_irq_restore(flags);
+ return val;
+}
+EXPORT_SYMBOL(generic_atomic64_xchg);
+
+s64 generic_atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
+{
+ unsigned long flags;
+ arch_spinlock_t *lock = lock_addr(v);
+ s64 val;
+
+ local_irq_save(flags);
+ arch_spin_lock(lock);
+ val = v->counter;
+ if (val != u)
+ v->counter += a;
+ arch_spin_unlock(lock);
+ local_irq_restore(flags);
+
+ return val;
+}
+EXPORT_SYMBOL(generic_atomic64_fetch_add_unless);