linux/net/nfc/core.c
Eric Lapuyade d4ccb13280 NFC: Specify usage for targets found and target lost events
It is now specified that nfc_target_found() and nfc_target_lost() core
functions must not be called from an atomic context. This allow us to
serialize calls and protect the targets table using the nfc device lock
instead of a spinlock.

Signed-off-by: Eric Lapuyade <eric.lapuyade@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2012-05-15 17:28:00 -04:00

850 lines
17 KiB
C

/*
* Copyright (C) 2011 Instituto Nokia de Tecnologia
*
* Authors:
* Lauro Ramos Venancio <lauro.venancio@openbossa.org>
* Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the
* Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/nfc.h>
#include "nfc.h"
#define VERSION "0.1"
#define NFC_CHECK_PRES_FREQ_MS 2000
int nfc_devlist_generation;
DEFINE_MUTEX(nfc_devlist_mutex);
/**
* nfc_dev_up - turn on the NFC device
*
* @dev: The nfc device to be turned on
*
* The device remains up until the nfc_dev_down function is called.
*/
int nfc_dev_up(struct nfc_dev *dev)
{
int rc = 0;
pr_debug("dev_name=%s\n", dev_name(&dev->dev));
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (dev->dev_up) {
rc = -EALREADY;
goto error;
}
if (dev->ops->dev_up)
rc = dev->ops->dev_up(dev);
if (!rc)
dev->dev_up = true;
error:
device_unlock(&dev->dev);
return rc;
}
/**
* nfc_dev_down - turn off the NFC device
*
* @dev: The nfc device to be turned off
*/
int nfc_dev_down(struct nfc_dev *dev)
{
int rc = 0;
pr_debug("dev_name=%s\n", dev_name(&dev->dev));
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (!dev->dev_up) {
rc = -EALREADY;
goto error;
}
if (dev->polling || dev->active_target) {
rc = -EBUSY;
goto error;
}
if (dev->ops->dev_down)
dev->ops->dev_down(dev);
dev->dev_up = false;
error:
device_unlock(&dev->dev);
return rc;
}
/**
* nfc_start_poll - start polling for nfc targets
*
* @dev: The nfc device that must start polling
* @protocols: bitset of nfc protocols that must be used for polling
*
* The device remains polling for targets until a target is found or
* the nfc_stop_poll function is called.
*/
int nfc_start_poll(struct nfc_dev *dev, u32 protocols)
{
int rc;
pr_debug("dev_name=%s protocols=0x%x\n",
dev_name(&dev->dev), protocols);
if (!protocols)
return -EINVAL;
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (dev->polling) {
rc = -EBUSY;
goto error;
}
rc = dev->ops->start_poll(dev, protocols);
if (!rc)
dev->polling = true;
error:
device_unlock(&dev->dev);
return rc;
}
/**
* nfc_stop_poll - stop polling for nfc targets
*
* @dev: The nfc device that must stop polling
*/
int nfc_stop_poll(struct nfc_dev *dev)
{
int rc = 0;
pr_debug("dev_name=%s\n", dev_name(&dev->dev));
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (!dev->polling) {
rc = -EINVAL;
goto error;
}
dev->ops->stop_poll(dev);
dev->polling = false;
error:
device_unlock(&dev->dev);
return rc;
}
static struct nfc_target *nfc_find_target(struct nfc_dev *dev, u32 target_idx)
{
int i;
if (dev->n_targets == 0)
return NULL;
for (i = 0; i < dev->n_targets ; i++) {
if (dev->targets[i].idx == target_idx)
return &dev->targets[i];
}
return NULL;
}
int nfc_dep_link_up(struct nfc_dev *dev, int target_index, u8 comm_mode)
{
int rc = 0;
u8 *gb;
size_t gb_len;
struct nfc_target *target;
pr_debug("dev_name=%s comm %d\n", dev_name(&dev->dev), comm_mode);
if (!dev->ops->dep_link_up)
return -EOPNOTSUPP;
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (dev->dep_link_up == true) {
rc = -EALREADY;
goto error;
}
gb = nfc_llcp_general_bytes(dev, &gb_len);
if (gb_len > NFC_MAX_GT_LEN) {
rc = -EINVAL;
goto error;
}
target = nfc_find_target(dev, target_index);
if (target == NULL) {
rc = -ENOTCONN;
goto error;
}
rc = dev->ops->dep_link_up(dev, target, comm_mode, gb, gb_len);
if (!rc)
dev->active_target = target;
error:
device_unlock(&dev->dev);
return rc;
}
int nfc_dep_link_down(struct nfc_dev *dev)
{
int rc = 0;
pr_debug("dev_name=%s\n", dev_name(&dev->dev));
if (!dev->ops->dep_link_down)
return -EOPNOTSUPP;
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (dev->dep_link_up == false) {
rc = -EALREADY;
goto error;
}
if (dev->dep_rf_mode == NFC_RF_TARGET) {
rc = -EOPNOTSUPP;
goto error;
}
rc = dev->ops->dep_link_down(dev);
if (!rc) {
dev->dep_link_up = false;
dev->active_target = NULL;
nfc_llcp_mac_is_down(dev);
nfc_genl_dep_link_down_event(dev);
}
error:
device_unlock(&dev->dev);
return rc;
}
int nfc_dep_link_is_up(struct nfc_dev *dev, u32 target_idx,
u8 comm_mode, u8 rf_mode)
{
dev->dep_link_up = true;
dev->dep_rf_mode = rf_mode;
nfc_llcp_mac_is_up(dev, target_idx, comm_mode, rf_mode);
return nfc_genl_dep_link_up_event(dev, target_idx, comm_mode, rf_mode);
}
EXPORT_SYMBOL(nfc_dep_link_is_up);
/**
* nfc_activate_target - prepare the target for data exchange
*
* @dev: The nfc device that found the target
* @target_idx: index of the target that must be activated
* @protocol: nfc protocol that will be used for data exchange
*/
int nfc_activate_target(struct nfc_dev *dev, u32 target_idx, u32 protocol)
{
int rc;
struct nfc_target *target;
pr_debug("dev_name=%s target_idx=%u protocol=%u\n",
dev_name(&dev->dev), target_idx, protocol);
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (dev->active_target) {
rc = -EBUSY;
goto error;
}
target = nfc_find_target(dev, target_idx);
if (target == NULL) {
rc = -ENOTCONN;
goto error;
}
rc = dev->ops->activate_target(dev, target, protocol);
if (!rc) {
dev->active_target = target;
if (dev->ops->check_presence)
mod_timer(&dev->check_pres_timer, jiffies +
msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
}
error:
device_unlock(&dev->dev);
return rc;
}
/**
* nfc_deactivate_target - deactivate a nfc target
*
* @dev: The nfc device that found the target
* @target_idx: index of the target that must be deactivated
*/
int nfc_deactivate_target(struct nfc_dev *dev, u32 target_idx)
{
int rc = 0;
pr_debug("dev_name=%s target_idx=%u\n",
dev_name(&dev->dev), target_idx);
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
goto error;
}
if (dev->active_target == NULL) {
rc = -ENOTCONN;
goto error;
}
if (dev->active_target->idx != target_idx) {
rc = -ENOTCONN;
goto error;
}
if (dev->ops->check_presence)
del_timer_sync(&dev->check_pres_timer);
dev->ops->deactivate_target(dev, dev->active_target);
dev->active_target = NULL;
error:
device_unlock(&dev->dev);
return rc;
}
/**
* nfc_data_exchange - transceive data
*
* @dev: The nfc device that found the target
* @target_idx: index of the target
* @skb: data to be sent
* @cb: callback called when the response is received
* @cb_context: parameter for the callback function
*
* The user must wait for the callback before calling this function again.
*/
int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx, struct sk_buff *skb,
data_exchange_cb_t cb, void *cb_context)
{
int rc;
pr_debug("dev_name=%s target_idx=%u skb->len=%u\n",
dev_name(&dev->dev), target_idx, skb->len);
device_lock(&dev->dev);
if (!device_is_registered(&dev->dev)) {
rc = -ENODEV;
kfree_skb(skb);
goto error;
}
if (dev->active_target == NULL) {
rc = -ENOTCONN;
kfree_skb(skb);
goto error;
}
if (dev->active_target->idx != target_idx) {
rc = -EADDRNOTAVAIL;
kfree_skb(skb);
goto error;
}
if (dev->ops->check_presence)
del_timer_sync(&dev->check_pres_timer);
rc = dev->ops->data_exchange(dev, dev->active_target, skb, cb,
cb_context);
if (!rc && dev->ops->check_presence)
mod_timer(&dev->check_pres_timer, jiffies +
msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
error:
device_unlock(&dev->dev);
return rc;
}
int nfc_set_remote_general_bytes(struct nfc_dev *dev, u8 *gb, u8 gb_len)
{
pr_debug("dev_name=%s gb_len=%d\n", dev_name(&dev->dev), gb_len);
if (gb_len > NFC_MAX_GT_LEN)
return -EINVAL;
return nfc_llcp_set_remote_gb(dev, gb, gb_len);
}
EXPORT_SYMBOL(nfc_set_remote_general_bytes);
/**
* nfc_alloc_send_skb - allocate a skb for data exchange responses
*
* @size: size to allocate
* @gfp: gfp flags
*/
struct sk_buff *nfc_alloc_send_skb(struct nfc_dev *dev, struct sock *sk,
unsigned int flags, unsigned int size,
unsigned int *err)
{
struct sk_buff *skb;
unsigned int total_size;
total_size = size +
dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
skb = sock_alloc_send_skb(sk, total_size, flags & MSG_DONTWAIT, err);
if (skb)
skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
return skb;
}
/**
* nfc_alloc_recv_skb - allocate a skb for data exchange responses
*
* @size: size to allocate
* @gfp: gfp flags
*/
struct sk_buff *nfc_alloc_recv_skb(unsigned int size, gfp_t gfp)
{
struct sk_buff *skb;
unsigned int total_size;
total_size = size + 1;
skb = alloc_skb(total_size, gfp);
if (skb)
skb_reserve(skb, 1);
return skb;
}
EXPORT_SYMBOL(nfc_alloc_recv_skb);
/**
* nfc_targets_found - inform that targets were found
*
* @dev: The nfc device that found the targets
* @targets: array of nfc targets found
* @ntargets: targets array size
*
* The device driver must call this function when one or many nfc targets
* are found. After calling this function, the device driver must stop
* polling for targets.
* IMPORTANT: this function must not be called from an atomic context.
* In addition, it must also not be called from a context that would prevent
* the NFC Core to call other nfc ops entry point concurrently.
*/
int nfc_targets_found(struct nfc_dev *dev,
struct nfc_target *targets, int n_targets)
{
int i;
pr_debug("dev_name=%s n_targets=%d\n", dev_name(&dev->dev), n_targets);
dev->polling = false;
for (i = 0; i < n_targets; i++)
targets[i].idx = dev->target_next_idx++;
device_lock(&dev->dev);
dev->targets_generation++;
kfree(dev->targets);
dev->targets = kmemdup(targets, n_targets * sizeof(struct nfc_target),
GFP_ATOMIC);
if (!dev->targets) {
dev->n_targets = 0;
device_unlock(&dev->dev);
return -ENOMEM;
}
dev->n_targets = n_targets;
device_unlock(&dev->dev);
nfc_genl_targets_found(dev);
return 0;
}
EXPORT_SYMBOL(nfc_targets_found);
/**
* nfc_target_lost - inform that an activated target went out of field
*
* @dev: The nfc device that had the activated target in field
* @target_idx: the nfc index of the target
*
* The device driver must call this function when the activated target
* goes out of the field.
* IMPORTANT: this function must not be called from an atomic context.
* In addition, it must also not be called from a context that would prevent
* the NFC Core to call other nfc ops entry point concurrently.
*/
int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
{
struct nfc_target *tg;
int i;
pr_debug("dev_name %s n_target %d\n", dev_name(&dev->dev), target_idx);
device_lock(&dev->dev);
for (i = 0; i < dev->n_targets; i++) {
tg = &dev->targets[i];
if (tg->idx == target_idx)
break;
}
if (i == dev->n_targets) {
device_unlock(&dev->dev);
return -EINVAL;
}
dev->targets_generation++;
dev->n_targets--;
dev->active_target = NULL;
if (dev->n_targets) {
memcpy(&dev->targets[i], &dev->targets[i + 1],
(dev->n_targets - i) * sizeof(struct nfc_target));
} else {
kfree(dev->targets);
dev->targets = NULL;
}
device_unlock(&dev->dev);
nfc_genl_target_lost(dev, target_idx);
return 0;
}
EXPORT_SYMBOL(nfc_target_lost);
static void nfc_release(struct device *d)
{
struct nfc_dev *dev = to_nfc_dev(d);
pr_debug("dev_name=%s\n", dev_name(&dev->dev));
if (dev->ops->check_presence) {
del_timer_sync(&dev->check_pres_timer);
destroy_workqueue(dev->check_pres_wq);
}
nfc_genl_data_exit(&dev->genl_data);
kfree(dev->targets);
kfree(dev);
}
static void nfc_check_pres_work(struct work_struct *work)
{
struct nfc_dev *dev = container_of(work, struct nfc_dev,
check_pres_work);
int rc;
device_lock(&dev->dev);
if (dev->active_target && timer_pending(&dev->check_pres_timer) == 0) {
rc = dev->ops->check_presence(dev, dev->active_target);
if (!rc) {
mod_timer(&dev->check_pres_timer, jiffies +
msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
} else {
u32 active_target_idx = dev->active_target->idx;
device_unlock(&dev->dev);
nfc_target_lost(dev, active_target_idx);
return;
}
}
device_unlock(&dev->dev);
}
static void nfc_check_pres_timeout(unsigned long data)
{
struct nfc_dev *dev = (struct nfc_dev *)data;
queue_work(dev->check_pres_wq, &dev->check_pres_work);
}
struct class nfc_class = {
.name = "nfc",
.dev_release = nfc_release,
};
EXPORT_SYMBOL(nfc_class);
static int match_idx(struct device *d, void *data)
{
struct nfc_dev *dev = to_nfc_dev(d);
unsigned int *idx = data;
return dev->idx == *idx;
}
struct nfc_dev *nfc_get_device(unsigned int idx)
{
struct device *d;
d = class_find_device(&nfc_class, NULL, &idx, match_idx);
if (!d)
return NULL;
return to_nfc_dev(d);
}
/**
* nfc_allocate_device - allocate a new nfc device
*
* @ops: device operations
* @supported_protocols: NFC protocols supported by the device
*/
struct nfc_dev *nfc_allocate_device(struct nfc_ops *ops,
u32 supported_protocols,
int tx_headroom, int tx_tailroom)
{
static atomic_t dev_no = ATOMIC_INIT(0);
struct nfc_dev *dev;
if (!ops->start_poll || !ops->stop_poll || !ops->activate_target ||
!ops->deactivate_target || !ops->data_exchange)
return NULL;
if (!supported_protocols)
return NULL;
dev = kzalloc(sizeof(struct nfc_dev), GFP_KERNEL);
if (!dev)
return NULL;
dev->dev.class = &nfc_class;
dev->idx = atomic_inc_return(&dev_no) - 1;
dev_set_name(&dev->dev, "nfc%d", dev->idx);
device_initialize(&dev->dev);
dev->ops = ops;
dev->supported_protocols = supported_protocols;
dev->tx_headroom = tx_headroom;
dev->tx_tailroom = tx_tailroom;
nfc_genl_data_init(&dev->genl_data);
/* first generation must not be 0 */
dev->targets_generation = 1;
if (ops->check_presence) {
char name[32];
init_timer(&dev->check_pres_timer);
dev->check_pres_timer.data = (unsigned long)dev;
dev->check_pres_timer.function = nfc_check_pres_timeout;
INIT_WORK(&dev->check_pres_work, nfc_check_pres_work);
snprintf(name, sizeof(name), "nfc%d_check_pres_wq", dev->idx);
dev->check_pres_wq = alloc_workqueue(name, WQ_NON_REENTRANT |
WQ_UNBOUND |
WQ_MEM_RECLAIM, 1);
if (dev->check_pres_wq == NULL) {
kfree(dev);
return NULL;
}
}
return dev;
}
EXPORT_SYMBOL(nfc_allocate_device);
/**
* nfc_register_device - register a nfc device in the nfc subsystem
*
* @dev: The nfc device to register
*/
int nfc_register_device(struct nfc_dev *dev)
{
int rc;
pr_debug("dev_name=%s\n", dev_name(&dev->dev));
mutex_lock(&nfc_devlist_mutex);
nfc_devlist_generation++;
rc = device_add(&dev->dev);
mutex_unlock(&nfc_devlist_mutex);
if (rc < 0)
return rc;
rc = nfc_llcp_register_device(dev);
if (rc)
pr_err("Could not register llcp device\n");
rc = nfc_genl_device_added(dev);
if (rc)
pr_debug("The userspace won't be notified that the device %s was added\n",
dev_name(&dev->dev));
return 0;
}
EXPORT_SYMBOL(nfc_register_device);
/**
* nfc_unregister_device - unregister a nfc device in the nfc subsystem
*
* @dev: The nfc device to unregister
*/
void nfc_unregister_device(struct nfc_dev *dev)
{
int rc;
pr_debug("dev_name=%s\n", dev_name(&dev->dev));
mutex_lock(&nfc_devlist_mutex);
nfc_devlist_generation++;
/* lock to avoid unregistering a device while an operation
is in progress */
device_lock(&dev->dev);
device_del(&dev->dev);
device_unlock(&dev->dev);
mutex_unlock(&nfc_devlist_mutex);
nfc_llcp_unregister_device(dev);
rc = nfc_genl_device_removed(dev);
if (rc)
pr_debug("The userspace won't be notified that the device %s was removed\n",
dev_name(&dev->dev));
}
EXPORT_SYMBOL(nfc_unregister_device);
static int __init nfc_init(void)
{
int rc;
pr_info("NFC Core ver %s\n", VERSION);
rc = class_register(&nfc_class);
if (rc)
return rc;
rc = nfc_genl_init();
if (rc)
goto err_genl;
/* the first generation must not be 0 */
nfc_devlist_generation = 1;
rc = rawsock_init();
if (rc)
goto err_rawsock;
rc = nfc_llcp_init();
if (rc)
goto err_llcp_sock;
rc = af_nfc_init();
if (rc)
goto err_af_nfc;
return 0;
err_af_nfc:
nfc_llcp_exit();
err_llcp_sock:
rawsock_exit();
err_rawsock:
nfc_genl_exit();
err_genl:
class_unregister(&nfc_class);
return rc;
}
static void __exit nfc_exit(void)
{
af_nfc_exit();
nfc_llcp_exit();
rawsock_exit();
nfc_genl_exit();
class_unregister(&nfc_class);
}
subsys_initcall(nfc_init);
module_exit(nfc_exit);
MODULE_AUTHOR("Lauro Ramos Venancio <lauro.venancio@openbossa.org>");
MODULE_DESCRIPTION("NFC Core ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");