// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2015-2018 Netronome Systems, Inc. */
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/jiffies.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include "nfp_cpp.h"
#include "nfp6000/nfp6000.h"
struct nfp_cpp_mutex {
struct nfp_cpp *cpp;
int target;
u16 depth;
unsigned long long address;
u32 key;
};
static u32 nfp_mutex_locked(u16 interface)
{
return (u32)interface << 16 | 0x000f;
}
static u32 nfp_mutex_unlocked(u16 interface)
{
return (u32)interface << 16 | 0x0000;
}
static u32 nfp_mutex_owner(u32 val)
{
return val >> 16;
}
static bool nfp_mutex_is_locked(u32 val)
{
return (val & 0xffff) == 0x000f;
}
static bool nfp_mutex_is_unlocked(u32 val)
{
return (val & 0xffff) == 0000;
}
/* If you need more than 65536 recursive locks, please rethink your code. */
#define NFP_MUTEX_DEPTH_MAX 0xffff
static int
nfp_cpp_mutex_validate(u16 interface, int *target, unsigned long long address)
{
/* Not permitted on invalid interfaces */
if (NFP_CPP_INTERFACE_TYPE_of(interface) ==
NFP_CPP_INTERFACE_TYPE_INVALID)
return -EINVAL;
/* Address must be 64-bit aligned */
if (address & 7)
return -EINVAL;
if (*target != NFP_CPP_TARGET_MU)
return -EINVAL;
return 0;
}
/**
* nfp_cpp_mutex_init() - Initialize a mutex location
* @cpp: NFP CPP handle
* @target: NFP CPP target ID (ie NFP_CPP_TARGET_CLS or NFP_CPP_TARGET_MU)
* @address: Offset into the address space of the NFP CPP target ID
* @key: Unique 32-bit value for this mutex
*
* The CPP target:address must point to a 64-bit aligned location, and
* will initialize 64 bits of data at the location.
*
* This creates the initial mutex state, as locked by this
* nfp_cpp_interface().
*
* This function should only be called when setting up
* the initial lock state upon boot-up of the system.
*
* Return: 0 on success, or -errno on failure
*/
int nfp_cpp_mutex_init(struct nfp_cpp *cpp,
int target, unsigned long long address, u32 key)
{
const u32 muw = NFP_CPP_ID(target, 4, 0); /* atomic_write */
u16 interface = nfp_cpp_interface(cpp);
int err;
err = nfp_cpp_mutex_validate(interface, &target, address);
if (err)
return err;
err = nfp_cpp_writel(cpp, muw, address + 4, key);
if (err)
return err;
err = nfp_cpp_writel(cpp, muw, address, nfp_mutex_locked(interface));
if (err)
return err;
return 0;
}
/**
* nfp_cpp_mutex_alloc() - Create a mutex handle
* @cpp: NFP CPP handle
* @target: NFP CPP target ID (ie NFP_CPP_TARGET_CLS or NFP_CPP_TARGET_MU)
* @address: Offset into the address space of the NFP CPP target ID
* @key: 32-bit unique key (must match the key at this location)
*
* The CPP target:address must point to a 64-bit aligned location, and
* reserve 64 bits of data at the location for use by the handle.
*
* Only target/address pairs that point to entities that support the
* MU Atomic Engine's CmpAndSwap32 command are supported.
*
* Return: A non-NULL struct nfp_cpp_mutex * on success, NULL on failure.
*/
struct nfp_cpp_mutex *nfp_cpp_mutex_alloc(struct nfp_cpp *cpp, int target,
unsigned long long address, u32 key)
{
const u32 mur = NFP_CPP_ID(target, 3, 0); /* atomic_read */
u16 interface = nfp_cpp_interface(cpp);
struct nfp_cpp_mutex *mutex;
int err;
u32 tmp;
err = nfp_cpp_mutex_validate(interface, &target, address);
if (err)
return NULL;
err = nfp_cpp_readl(cpp, mur, address + 4, &tmp);
if (err < 0)
return NULL;
if (tmp != key)
return NULL;
mutex = kzalloc(sizeof(*mutex), GFP_KERNEL);
if (!mutex)
return NULL;
mutex->cpp = cpp;
mutex->target = target;
mutex->address = address;
mutex->key = key;
mutex->depth = 0;
return mutex;
}
/**
* nfp_cpp_mutex_free() - Free a mutex handle - does not alter the lock state
* @mutex: NFP CPP Mutex handle
*/
void nfp_cpp_mutex_free(struct nfp_cpp_mutex *mutex)
{
kfree(mutex);
}
/**
* nfp_cpp_mutex_lock() - Lock a mutex handle, using the NFP MU Atomic Engine
* @mutex: NFP CPP Mutex handle
*
* Return: 0 on success, or -errno on failure
*/
int nfp_cpp_mutex_lock(struct nfp_cpp_mutex *mutex)
{
unsigned long warn_at = jiffies + NFP_MUTEX_WAIT_FIRST_WARN * HZ;
unsigned long err_at = jiffies + NFP_MUTEX_WAIT_ERROR * HZ;
unsigned int timeout_ms = 1;
int err;
/* We can't use a waitqueue here, because the unlocker
* might be on a separate CPU.
*
* So just wait for now.
*/
for (;;) {
err = nfp_cpp_mutex_trylock(mutex);
if (err != -EBUSY)
break;
err = msleep_interruptible(timeout_ms);
if (err != 0) {
nfp_info(mutex->cpp,
"interrupted waiting for NFP mutex\n");
return -ERESTARTSYS;
}
if (time_is_before_eq_jiffies(warn_at)) {
warn_at = jiffies + NFP_MUTEX_WAIT_NEXT_WARN * HZ;
nfp_warn(mutex->cpp,
"Warning: waiting for NFP mutex [depth:%hd target:%d addr:%llx key:%08x]\n",
mutex->depth,
mutex->target, mutex->address, mutex->key);
}
if (time_is_before_eq_jiffies(err_at)) {
nfp_err(mutex->cpp, "Error: mutex wait timed out\n");
return -EBUSY;
}
}
return err;
}
/**
* nfp_cpp_mutex_unlock() - Unlock a mutex handle, using the MU Atomic Engine
* @mutex: NFP CPP Mutex handle
*
* Return: 0 on success, or -errno on failure
*/
int nfp_cpp_mutex_unlock(struct nfp_cpp_mutex *mutex)
{
const u32 muw = NFP_CPP_ID(mutex->target, 4, 0); /* atomic_write */
const u32 mur = NFP_CPP_ID(mutex->target, 3, 0); /* atomic_read */
struct nfp_cpp *cpp = mutex->cpp;
u32 key, value;
u16 interface;
int err;
interface = nfp_cpp_interface(cpp);
if (mutex->depth > 1) {
mutex->depth--;
return 0;
}
err = nfp_cpp_readl(mutex->cpp, mur, mutex->address + 4, &key);
if (err < 0)
return err;
if (key != mutex->key)
return -EPERM;
err = nfp_cpp_readl(mutex->cpp, mur, mutex->address, &value);
if (err < 0)
return err;
if (value != nfp_mutex_locked(interface))
return -EACCES;
err = nfp_cpp_writel(cpp, muw, mutex->address,
nfp_mutex_unlocked(interface));
if (err < 0)
return err;
mutex->depth = 0;
return 0;
}
/**
* nfp_cpp_mutex_trylock() - Attempt to lock a mutex handle
* @mutex: NFP CPP Mutex handle
*
* Return: 0 if the lock succeeded, -errno on failure
*/
int nfp_cpp_mutex_trylock(struct nfp_cpp_mutex *mutex)
{
const u32 muw = NFP_CPP_ID(mutex->target, 4, 0); /* atomic_write */
const u32 mus = NFP_CPP_ID(mutex->target, 5, 3); /* test_set_imm */
const u32 mur = NFP_CPP_ID(mutex->target, 3, 0); /* atomic_read */
struct nfp_cpp *cpp = mutex->cpp;
u32 key, value, tmp;
int err;
if (mutex->depth > 0) {
if (mutex->depth == NFP_MUTEX_DEPTH_MAX)
return -E2BIG;
mutex->depth++;
return 0;
}
/* Verify that the lock marker is not damaged */
err = nfp_cpp_readl(cpp, mur, mutex->address + 4, &key);
if (err < 0)
return err;
if (key != mutex->key)
return -EPERM;
/* Compare against the unlocked state, and if true,
* write the interface id into the top 16 bits, and
* mark as locked.
*/
value = nfp_mutex_locked(nfp_cpp_interface(cpp));
/* We use test_set_imm here, as it implies a read
* of the current state, and sets the bits in the
* bytemask of the command to 1s. Since the mutex
* is guaranteed to be 64-bit aligned, the bytemask
* of this 32-bit command is ensured to be 8'b00001111,
* which implies that the lower 4 bits will be set to
* ones regardless of the initial state.
*
* Since this is a 'Readback' operation, with no Pull
* data, we can treat this as a normal Push (read)
* atomic, which returns the original value.
*/
err = nfp_cpp_readl(cpp, mus, mutex->address, &tmp);
if (err < 0)
return err;
/* Was it unlocked? */
if (nfp_mutex_is_unlocked(tmp)) {
/* The read value can only be 0x....0000 in the unlocked state.
* If there was another contending for this lock, then
* the lock state would be 0x....000f
*/
/* Write our owner ID into the lock
* While not strictly necessary, this helps with
* debug and bookkeeping.
*/
err = nfp_cpp_writel(cpp, muw, mutex->address, value);
if (err < 0)
return err;
mutex->depth = 1;
return 0;
}
return nfp_mutex_is_locked(tmp) ? -EBUSY : -EINVAL;
}
/**
* nfp_cpp_mutex_reclaim() - Unlock mutex if held by local endpoint
* @cpp: NFP CPP handle
* @target: NFP CPP target ID (ie NFP_CPP_TARGET_CLS or NFP_CPP_TARGET_MU)
* @address: Offset into the address space of the NFP CPP target ID
*
* Release lock if held by local system. Extreme care is advised, call only
* when no local lock users can exist.
*
* Return: 0 if the lock was OK, 1 if locked by us, -errno on invalid mutex
*/
int nfp_cpp_mutex_reclaim(struct nfp_cpp *cpp, int target,
unsigned long long address)
{
const u32 mur = NFP_CPP_ID(target, 3, 0); /* atomic_read */
const u32 muw = NFP_CPP_ID(target, 4, 0); /* atomic_write */
u16 interface = nfp_cpp_interface(cpp);
int err;
u32 tmp;
err = nfp_cpp_mutex_validate(interface, &target, address);
if (err)
return err;
/* Check lock */
err = nfp_cpp_readl(cpp, mur, address, &tmp);
if (err < 0)
return err;
if (nfp_mutex_is_unlocked(tmp) || nfp_mutex_owner(tmp) != interface)
return 0;
/* Bust the lock */
err = nfp_cpp_writel(cpp, muw, address, nfp_mutex_unlocked(interface));
if (err < 0)
return err;
return 1;
}
Codebase Browser
linux