drivers/media/cec/cec-notifier.c

   1 /*
   2  * cec-notifier.c - notify CEC drivers of physical address changes
   3  *
   4  * Copyright 2016 Russell King <rmk+kernel@arm.linux.org.uk>
   5  * Copyright 2016-2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   6  *
   7  * This program is free software; you may redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; version 2 of the License.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  12  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  13  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  14  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  15  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  16  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  17  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  18  * SOFTWARE.
  19  */
  20
  21 #include <linux/export.h>
  22 #include <linux/string.h>
  23 #include <linux/slab.h>
  24 #include <linux/list.h>
  25 #include <linux/kref.h>
  26
  27 #include <media/cec.h>
  28 #include <media/cec-notifier.h>
  29 #include <drm/drm_edid.h>
  30
  31 struct cec_notifier {
  32         struct mutex lock;
  33         struct list_head head;
  34         struct kref kref;
  35         struct device *dev;
  36         struct cec_adapter *cec_adap;
  37         void (*callback)(struct cec_adapter *adap, u16 pa);
  38
  39         u16 phys_addr;
  40 };
  41
  42 static LIST_HEAD(cec_notifiers);
  43 static DEFINE_MUTEX(cec_notifiers_lock);
  44
  45 struct cec_notifier *cec_notifier_get(struct device *dev)
  46 {
  47         struct cec_notifier *n;
  48
  49         mutex_lock(&cec_notifiers_lock);
  50         list_for_each_entry(n, &cec_notifiers, head) {
  51                 if (n->dev == dev) {
  52                         kref_get(&n->kref);
  53                         mutex_unlock(&cec_notifiers_lock);
  54                         return n;
  55                 }
  56         }
  57         n = kzalloc(sizeof(*n), GFP_KERNEL);
  58         if (!n)
  59                 goto unlock;
  60         n->dev = dev;
  61         n->phys_addr = CEC_PHYS_ADDR_INVALID;
  62         mutex_init(&n->lock);
  63         kref_init(&n->kref);
  64         list_add_tail(&n->head, &cec_notifiers);
  65 unlock:
  66         mutex_unlock(&cec_notifiers_lock);
  67         return n;
  68 }
  69 EXPORT_SYMBOL_GPL(cec_notifier_get);
  70
  71 static void cec_notifier_release(struct kref *kref)
  72 {
  73         struct cec_notifier *n =
  74                 container_of(kref, struct cec_notifier, kref);
  75
  76         list_del(&n->head);
  77         kfree(n);
  78 }
  79
  80 void cec_notifier_put(struct cec_notifier *n)
  81 {
  82         mutex_lock(&cec_notifiers_lock);
  83         kref_put(&n->kref, cec_notifier_release);
  84         mutex_unlock(&cec_notifiers_lock);
  85 }
  86 EXPORT_SYMBOL_GPL(cec_notifier_put);
  87
  88 void cec_notifier_set_phys_addr(struct cec_notifier *n, u16 pa)
  89 {
  90         if (n == NULL)
  91                 return;
  92
  93         mutex_lock(&n->lock);
  94         n->phys_addr = pa;
  95         if (n->callback)
  96                 n->callback(n->cec_adap, n->phys_addr);
  97         mutex_unlock(&n->lock);
  98 }
  99 EXPORT_SYMBOL_GPL(cec_notifier_set_phys_addr);
 100
 101 void cec_notifier_set_phys_addr_from_edid(struct cec_notifier *n,
 102                                           const struct edid *edid)
 103 {
 104         u16 pa = CEC_PHYS_ADDR_INVALID;
 105
 106         if (n == NULL)
 107                 return;
 108
 109         if (edid && edid->extensions)
 110                 pa = cec_get_edid_phys_addr((const u8 *)edid,
 111                                 EDID_LENGTH * (edid->extensions + 1), NULL);
 112         cec_notifier_set_phys_addr(n, pa);
 113 }
 114 EXPORT_SYMBOL_GPL(cec_notifier_set_phys_addr_from_edid);
 115
 116 void cec_notifier_register(struct cec_notifier *n,
 117                            struct cec_adapter *adap,
 118                            void (*callback)(struct cec_adapter *adap, u16 pa))
 119 {
 120         kref_get(&n->kref);
 121         mutex_lock(&n->lock);
 122         n->cec_adap = adap;
 123         n->callback = callback;
 124         n->callback(adap, n->phys_addr);
 125         mutex_unlock(&n->lock);
 126 }
 127 EXPORT_SYMBOL_GPL(cec_notifier_register);
 128
 129 void cec_notifier_unregister(struct cec_notifier *n)
 130 {
 131         mutex_lock(&n->lock);
 132         n->callback = NULL;
 133         mutex_unlock(&n->lock);
 134         cec_notifier_put(n);
 135 }
 136 EXPORT_SYMBOL_GPL(cec_notifier_unregister);