diff options
Diffstat (limited to 'drivers/net/ethernet/netronome/nfp/nfpcore/nfp_mutex.c')
| -rw-r--r-- | drivers/net/ethernet/netronome/nfp/nfpcore/nfp_mutex.c | 345 |
1 files changed, 345 insertions, 0 deletions
diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_mutex.c b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_mutex.c new file mode 100644 index 000000000000..8a99c189efa8 --- /dev/null +++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_mutex.c @@ -0,0 +1,345 @@ +/* + * Copyright (C) 2015-2017 Netronome Systems, Inc. + * + * This software is dual licensed under the GNU General License Version 2, + * June 1991 as shown in the file COPYING in the top-level directory of this + * source tree or the BSD 2-Clause License provided below. You have the + * option to license this software under the complete terms of either license. + * + * The BSD 2-Clause License: + * + * Redistribution and use in source and binary forms, with or + * without modification, are permitted provided that the following + * conditions are met: + * + * 1. Redistributions of source code must retain the above + * copyright notice, this list of conditions and the following + * disclaimer. + * + * 2. Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials + * provided with the distribution. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#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 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 + 15 * 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) + return -ERESTARTSYS; + + if (time_is_before_eq_jiffies(warn_at)) { + warn_at = jiffies + 60 * 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); + } + } + + 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; +} |