fix unmapping problem

ws2811.c

@@ -115,6 +115,24 @@ static int max_channel_led_count(ws2811_t *ws2811)
     return max;
 }
 
+/**
+ * Unmap a physical address and length from virtual memory.
+ *
+ * @param    addr  Virtual address pointer of device registers.
+ * @param    len   Length of mapped region.
+ *
+ * @returns  None
+ */
+static void unmap_device(volatile void *addr, const uint32_t len)
+{
+    uint32_t virt = (uint32_t)addr;
+    uint32_t start_page_addr = virt & PAGE_MASK;
+    uint32_t end_page_addr = (virt + len) & PAGE_MASK;
+    uint32_t pages = end_page_addr - start_page_addr + 1;
+
+    munmap((void *)addr, PAGE_SIZE * pages);
+}
+
 /**
  * Map all devices into userspace memory.
  *
@@ -173,22 +191,22 @@ static void unmap_registers(ws2811_t *ws2811)
 
     if (device->dma)
     {
-        unmapmem((void *)device->dma, sizeof(dma_t));
+        unmap_device(device->dma, sizeof(dma_t));
     }
 
     if (device->pwm)
     {
-        unmapmem((void *)device->pwm, sizeof(pwm_t));
+        unmap_device(device->pwm, sizeof(pwm_t));
     }
 
     if (device->cm_pwm)
     {
-        unmapmem((void *)device->cm_pwm, sizeof(cm_pwm_t));
+        unmap_device(device->cm_pwm, sizeof(cm_pwm_t));
     }
 
     if (device->gpio)
     {
-        unmapmem((void *)device->gpio, sizeof(gpio_t));
+        unmap_device(device->gpio, sizeof(gpio_t));
     }
 }