UART: Fixing UART issues on UP2

Signed-off-by: Abhishek Malik <abhishek.malik@intel.com>

include/mraa_internal.h

@@ -168,6 +168,16 @@ mraa_result_t mraa_atoi(char* intStr, int* value);
  */
 int mraa_find_i2c_bus_pci(const char* pci_device, const char *pci_id, const char* adapter_name);
 
+/**
+ * helper function to find the uart device based on pci data
+ *
+ * @param pci_dev_path points to the location of tty device which corresponds
+ * to the uart device available on the platform
+ * @param dev_name as retrieved from pci_dev_path
+ * @return Result of the operation
+ */
+mraa_result_t mraa_find_uart_bus_pci(const char* pci_dev_path, char** dev_name);
+
 #if defined(IMRAA)
 /**
  * read Imraa subplatform lock file, caller is responsible to free return

src/mraa.c

@@ -282,21 +282,22 @@ mraa_deinit()
             }
             free(sub_plat);
         }
-#if defined(JSONPLAT)
         if (plat->platform_type == MRAA_JSON_PLATFORM) {
             // Free the platform name
             free(plat->platform_name);
             plat->platform_name = NULL;
+        }
 
         int i = 0;
         // Free the UART device path
+        if ((plat->platform_type == MRAA_JSON_PLATFORM) || (plat->platform_type == MRAA_UP2)) {
             for (i = 0; i < plat->uart_dev_count; i++) {
                 if (plat->uart_dev[i].device_path != NULL) {
                     free(plat->uart_dev[i].device_path);
                 }
             }
         }
-#endif
+
         free(plat);
         plat = NULL;
 
@@ -1135,6 +1136,34 @@ mraa_link_targets(const char* filename, const char* targetname)
     }
 }
 
+mraa_result_t
+mraa_find_uart_bus_pci(const char* pci_dev_path, char** dev_name)
+{
+    char path[PATH_MAX];
+    const int max_allowable_len = 16;
+    snprintf(path, PATH_MAX - 1, "%s", pci_dev_path);
+    if (!mraa_file_exist(path)) {
+        return MRAA_ERROR_INVALID_PARAMETER;
+    }
+
+    struct dirent** namelist;
+    int n = scandir(path, &namelist, NULL, alphasort);
+    if (n <= 0) {
+        syslog(LOG_ERR, "Failed to find expected UART bus: %s", strerror(errno));
+        return MRAA_ERROR_INVALID_RESOURCE;
+    }
+
+    *dev_name = (char*) malloc(sizeof(char) * max_allowable_len);
+
+    snprintf(*dev_name, max_allowable_len, "/dev/%s", namelist[n - 1]->d_name);
+    while (n--) {
+        free(namelist[n]);
+    }
+    free(namelist);
+    syslog(LOG_INFO, "UART device: %s selected for initialization", *dev_name);
+    return MRAA_SUCCESS;
+}
+
 static int
 mraa_count_i2c_files(const char* path, const struct stat* sb, int flag, struct FTW* ftwb)
 {

src/x86/up2.c

@@ -242,7 +242,11 @@ mraa_up2_board()
     // Configure UART
     b->uart_dev_count = 0;
     b->def_uart_dev = 0;
-    b->uart_dev[0].device_path = "/dev/ttyS1";
+    // setting up a default path
+    if (mraa_find_uart_bus_pci("/sys/bus/pci/devices/0000:00:18.1/dw-apb-uart.9/tty/",
+                               &(b->uart_dev[0].device_path)) != MRAA_SUCCESS) {
+        goto error;
+    }
 
     // Configure UART #1 (default)
     mraa_up2_get_pin_index(b, "UART_RX", &(b->uart_dev[0].rx));