cc770_isa_port_write_reg_indirect(const struct cc770_priv *priv,
  						int reg, u8 val)
  {
  	unsigned long base = (unsigned long)priv->reg_base;
+	unsigned long flags;

+	spin_lock_irqsave( &outb_lock, flags);
  	outb(reg, base);
  	outb(val, base + 1);
+	spin_unlock_irqrestore( &outb_lock, flags);	

Is there a 'read_reg_indirect' function??
If so it also needs to use the same mutex.
I'd double check all references to the 'reg_base' field.

	David