V4L/DVB (13542): ir-keytable: Allow dynamic table change

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 197 insertions, 10 deletions

diff --git a/drivers/media/common/ir-keytable.c b/drivers/media/common/ir-keytable.c
index b06f023ca760..26ce5bc2fdd5 100644
--- a/drivers/media/common/ir-keytable.c
+++ b/drivers/media/common/ir-keytable.c
@@ -8,6 +8,7 @@
 #include <media/ir-common.h>
 
 #define IR_TAB_MIN_SIZE 32
+#define IR_TAB_MAX_SIZE 1024
 
 /**
  * ir_seek_table() - returns the element order on the table
@@ -121,7 +122,154 @@ static int ir_getkeycode(struct input_dev *dev,
                 return 0;
         }
 
-        return -EINVAL;
+        /*
+         * Scancode not found and table can't be expanded
+         */
+        if (elem < 0 && rc_tab->size == IR_TAB_MAX_SIZE)
+                return -EINVAL;
+
+        /*
+         * If is there extra space, returns KEY_RESERVED,
+         * otherwise, input core won't let ir_setkeycode to work
+         */
+        *keycode = KEY_RESERVED;
+        return 0;
+}
+
+
+/**
+ * ir_is_resize_needed() - Check if the table needs rezise
+ * @table:              keycode table that may need to resize
+ * @n_elems:            minimum number of entries to store keycodes
+ *
+ * Considering that kmalloc uses power of two storage areas, this
+ * routine detects if the real alloced size will change. If not, it
+ * just returns without doing nothing. Otherwise, it will extend or
+ * reduce the table size to meet the new needs.
+ *
+ * It returns 0 if no resize is needed, 1 otherwise.
+ */
+static int ir_is_resize_needed(struct ir_scancode_table *table, int n_elems)
+{
+        int cur_size = ir_roundup_tablesize(table->size);
+        int new_size = ir_roundup_tablesize(n_elems);
+
+        if (cur_size == new_size)
+                return 0;
+
+        /* Resize is needed */
+        return 1;
+}
+
+/**
+ * ir_delete_key() - remove a keycode from the table
+ * @rc_tab:             keycode table
+ * @elem:               element to be removed
+ *
+ */
+static void ir_delete_key(struct ir_scancode_table *rc_tab, int elem)
+{
+        unsigned long flags = 0;
+        int newsize = rc_tab->size - 1;
+        int resize = ir_is_resize_needed(rc_tab, newsize);
+        struct ir_scancode *oldkeymap = rc_tab->scan;
+        struct ir_scancode *newkeymap;
+
+        if (resize) {
+                newkeymap = kzalloc(ir_roundup_tablesize(newsize) *
+                                    sizeof(*newkeymap), GFP_ATOMIC);
+
+                /* There's no memory for resize. Keep the old table */
+                if (!newkeymap)
+                        resize = 0;
+        }
+
+        if (!resize) {
+                newkeymap = oldkeymap;
+
+                /* We'll modify the live table. Lock it */
+                spin_lock_irqsave(&rc_tab->lock, flags);
+        }
+
+        /*
+         * Copy the elements before the one that will be deleted
+         * if (!resize), both oldkeymap and newkeymap points
+         * to the same place, so, there's no need to copy
+         */
+        if (resize && elem > 0)
+                memcpy(newkeymap, oldkeymap,
+                       elem * sizeof(*newkeymap));
+
+        /*
+         * Copy the other elements overwriting the element to be removed
+         * This operation applies to both resize and non-resize case
+         */
+        if (elem < newsize)
+                memcpy(&newkeymap[elem], &oldkeymap[elem + 1],
+                       (newsize - elem) * sizeof(*newkeymap));
+
+        if (resize) {
+                /*
+                 * As the copy happened to a temporary table, only here
+                 * it needs to lock while replacing the table pointers
+                 * to use the new table
+                 */
+                spin_lock_irqsave(&rc_tab->lock, flags);
+                rc_tab->size = newsize;
+                rc_tab->scan = newkeymap;
+                spin_unlock_irqrestore(&rc_tab->lock, flags);
+
+                /* Frees the old keytable */
+                kfree(oldkeymap);
+        } else {
+                rc_tab->size = newsize;
+                spin_unlock_irqrestore(&rc_tab->lock, flags);
+        }
+}
+
+/**
+ * ir_insert_key() - insert a keycode at the table
+ * @rc_tab:             keycode table
+ * @scancode:   the desired scancode
+ * @keycode:    the keycode to be retorned.
+ *
+ */
+static int ir_insert_key(struct ir_scancode_table *rc_tab,
+                          int scancode, int keycode)
+{
+        unsigned long flags;
+        int elem = rc_tab->size;
+        int newsize = rc_tab->size + 1;
+        int resize = ir_is_resize_needed(rc_tab, newsize);
+        struct ir_scancode *oldkeymap = rc_tab->scan;
+        struct ir_scancode *newkeymap;
+
+        if (resize) {
+                newkeymap = kzalloc(ir_roundup_tablesize(newsize) *
+                                    sizeof(*newkeymap), GFP_ATOMIC);
+                if (!newkeymap)
+                        return -ENOMEM;
+
+                memcpy(newkeymap, oldkeymap,
+                       rc_tab->size * sizeof(*newkeymap));
+        } else
+                newkeymap  = oldkeymap;
+
+        /* Stores the new code at the table */
+        IR_dprintk(1, "#%d: New scan 0x%04x with key 0x%04x\n",
+                   rc_tab->size, scancode, keycode);
+
+        spin_lock_irqsave(&rc_tab->lock, flags);
+        rc_tab->size = newsize;
+        if (resize) {
+                rc_tab->scan = newkeymap;
+                kfree(oldkeymap);
+        }
+        newkeymap[elem].scancode = scancode;
+        newkeymap[elem].keycode  = keycode;
+        spin_unlock_irqrestore(&rc_tab->lock, flags);
+
+        return 0;
 }
 
 /**
@@ -142,20 +290,59 @@ static int ir_setkeycode(struct input_dev *dev,
         struct ir_scancode *keymap = rc_tab->scan;
         unsigned long flags;
 
-        /* Search if it is replacing an existing keycode */
+        /*
+         * Handle keycode table deletions
+         *
+         * If userspace is adding a KEY_UNKNOWN or KEY_RESERVED,
+         * deal as a trial to remove an existing scancode attribution
+         * if table become too big, reduce it to save space
+         */
+        if (keycode == KEY_UNKNOWN || keycode == KEY_RESERVED) {
+                rc = ir_seek_table(rc_tab, scancode);
+                if (rc < 0)
+                        return 0;
+
+                IR_dprintk(1, "#%d: Deleting scan 0x%04x\n", rc, scancode);
+                clear_bit(keymap[rc].keycode, dev->keybit);
+                ir_delete_key(rc_tab, rc);
+
+                return 0;
+        }
+
+        /*
+         * Handle keycode replacements
+         *
+         * If the scancode exists, just replace by the new value
+         */
         rc = ir_seek_table(rc_tab, scancode);
-        if (rc <0)
-                return rc;
+        if (rc >= 0) {
+                IR_dprintk(1, "#%d: Replacing scan 0x%04x with key 0x%04x\n",
+                        rc, scancode, keycode);
 
-        IR_dprintk(1, "#%d: Replacing scan 0x%04x with key 0x%04x\n",
-                rc, scancode, keycode);
+                clear_bit(keymap[rc].keycode, dev->keybit);
 
-        clear_bit(keymap[rc].keycode, dev->keybit);
+                spin_lock_irqsave(&rc_tab->lock, flags);
+                keymap[rc].keycode = keycode;
+                spin_unlock_irqrestore(&rc_tab->lock, flags);
 
-        spin_lock_irqsave(&rc_tab->lock, flags);
-        keymap[rc].keycode = keycode;
-        spin_unlock_irqrestore(&rc_tab->lock, flags);
+                set_bit(keycode, dev->keybit);
 
+                return 0;
+        }
+
+        /*
+         * Handle new scancode inserts
+         *
+         * reallocate table if needed and insert a new keycode
+         */
+
+        /* Avoid growing the table indefinitely */
+        if (rc_tab->size + 1 > IR_TAB_MAX_SIZE)
+                return -EINVAL;
+
+        rc = ir_insert_key(rc_tab, scancode, keycode);
+        if (rc < 0)
+                return rc;
         set_bit(keycode, dev->keybit);
 
         return 0;