uwb: add an ASIE sysfs attribute to uwb_rc devices

Allow user mode to add and remove application specific information
elements (ASIEs) to the beacon of a uwb_rc device.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 99 insertions, 0 deletions

diff --git a/drivers/uwb/lc-rc.c b/drivers/uwb/lc-rc.c
index 3eca6ceb9844..d059ad4d0dbd 100644
--- a/drivers/uwb/lc-rc.c
+++ b/drivers/uwb/lc-rc.c
@@ -119,10 +119,109 @@ struct uwb_rc *uwb_rc_alloc(void)
 }
 EXPORT_SYMBOL_GPL(uwb_rc_alloc);
 
+/*
+ * Show the ASIE that is broadcast in the UWB beacon by this uwb_rc device.
+ */
+static ssize_t ASIE_show(struct device *dev,
+                                struct device_attribute *attr, char *buf)
+{
+        struct uwb_dev *uwb_dev = to_uwb_dev(dev);
+        struct uwb_rc *rc = uwb_dev->rc;
+        struct uwb_ie_hdr *ie;
+        void *ptr;
+        size_t len;
+        int result = 0;
+
+        /* init empty buffer. */
+        result = scnprintf(buf, PAGE_SIZE, "\n");
+        mutex_lock(&rc->ies_mutex);
+        /* walk IEData looking for an ASIE. */
+        ptr = rc->ies->IEData;
+        len = le16_to_cpu(rc->ies->wIELength);
+        for (;;) {
+                ie = uwb_ie_next(&ptr, &len);
+                if (!ie)
+                        break;
+                if (ie->element_id == UWB_APP_SPEC_IE) {
+                        result = uwb_ie_dump_hex(ie,
+                                        ie->length + sizeof(struct uwb_ie_hdr),
+                                        buf, PAGE_SIZE);
+                        break;
+                }
+        }
+        mutex_unlock(&rc->ies_mutex);
+
+        return result;
+}
+
+/*
+ * Update the ASIE that is broadcast in the UWB beacon by this uwb_rc device.
+ */
+static ssize_t ASIE_store(struct device *dev,
+                                 struct device_attribute *attr,
+                                 const char *buf, size_t size)
+{
+        struct uwb_dev *uwb_dev = to_uwb_dev(dev);
+        struct uwb_rc *rc = uwb_dev->rc;
+        char ie_buf[255];
+        int result, ie_len = 0;
+        const char *cur_ptr = buf;
+        struct uwb_ie_hdr *ie;
+
+        /* empty string means clear the ASIE. */
+        if (strlen(buf) <= 1) {
+                uwb_rc_ie_rm(rc, UWB_APP_SPEC_IE);
+                return size;
+        }
+
+        /* if non-empty string, convert string of hex chars to binary. */
+        while (ie_len < sizeof(ie_buf)) {
+                int char_count;
+
+                if (sscanf(cur_ptr, " %02hhX %n",
+                                &(ie_buf[ie_len]), &char_count) > 0) {
+                        ++ie_len;
+                        /* skip chars read from cur_ptr. */
+                        cur_ptr += char_count;
+                } else {
+                        break;
+                }
+        }
+
+        /* validate IE length and type. */
+        if (ie_len < sizeof(struct uwb_ie_hdr)) {
+                dev_err(dev, "%s: Invalid ASIE size %d.\n", __func__, ie_len);
+                return -EINVAL;
+        }
+
+        ie = (struct uwb_ie_hdr *)ie_buf;
+        if (ie->element_id != UWB_APP_SPEC_IE) {
+                dev_err(dev, "%s: Invalid IE element type size = 0x%02X.\n",
+                                __func__, ie->element_id);
+                return -EINVAL;
+        }
+
+        /* bounds check length field from user. */
+        if (ie->length > (ie_len - sizeof(struct uwb_ie_hdr)))
+                ie->length = ie_len - sizeof(struct uwb_ie_hdr);
+
+        /*
+         * Valid ASIE received. Remove current ASIE then add the new one using
+         * uwb_rc_ie_add.
+         */
+        uwb_rc_ie_rm(rc, UWB_APP_SPEC_IE);
+
+        result = uwb_rc_ie_add(rc, ie, ie->length + sizeof(struct uwb_ie_hdr));
+
+        return result >= 0 ? size : result;
+}
+static DEVICE_ATTR_RW(ASIE);
+
 static struct attribute *rc_attrs[] = {
                 &dev_attr_mac_address.attr,
                 &dev_attr_scan.attr,
                 &dev_attr_beacon.attr,
+                &dev_attr_ASIE.attr,
                 NULL,
 };