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

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

diff --git a/drivers/media/common/ir-keytable.c b/drivers/media/common/ir-keytable.c
index b06f023ca76087cb1df4be684c07b1e7ff41a96c..26ce5bc2fdd545de4bf3088e655e1ec7e9a0507a 100644 (file)
--- 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;