drivers/at : Expose to Kconfig

Expose configurations to Kconfig:
Model choice for CONFIG_AT_SEND_EOL
Allow value to be configured as exponent for AT_BUF_SIZE

drivers/Kconfig

@@ -10,8 +10,11 @@ menu "Actuator Device Drivers"
 rsource "motor_driver/Kconfig"
 endmenu # Actuator Device Drivers
 
-rsource "Kconfig.net"
+menu "Miscellaneous Device Drivers"
+rsource "at/Kconfig"
+endmenu # Miscellaneous Device Drivers
 
+rsource "Kconfig.net"
 rsource "periph_common/Kconfig"
 
 menu "Sensor Device Drivers"

drivers/at/Kconfig

@@ -0,0 +1,63 @@
+# Copyright (c) 2020 Freie Universitaet Berlin
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+#
+menuconfig KCONFIG_MODULE_AT
+    bool "Configure AT driver"
+    depends on MODULE_AT
+    help
+        Configure the AT driver using Kconfig.
+
+if KCONFIG_MODULE_AT
+
+choice
+    bool "End of line character"
+    default AT_SEND_EOL_MAC
+    help
+        Select the EOL character to send after the AT command.
+        The character sequence depends on target device.
+        By default "\r", aka carriage return, is used.
+
+config AT_SEND_EOL_WINDOWS
+    bool "\\r\\n"
+
+config AT_SEND_EOL_UNIX
+    bool "\\n"
+
+config AT_SEND_EOL_MAC
+    bool "\\r"
+
+endchoice
+
+config AT_SEND_SKIP_ECHO
+    bool "Disable check for echo"
+    help
+        Enable this to disable check for echo after an AT
+        command is sent.
+
+config AT_RECV_OK
+    string "OK reply string"
+    default "OK"
+    help
+        Change okay response of the AT device.
+
+config AT_RECV_ERROR
+    string "Error reply string"
+    default "ERROR"
+    help
+        Change error response of the AT device.
+
+config AT_BUF_SIZE_EXP
+    int "Exponent for the buffer size (resulting in the queue size 2^n)"
+    range 0 31
+    default 7
+    depends on MODULE_AT_URC
+    help
+        Size of buffer used to process unsolicited result code data. (as
+        exponent of 2^n). As the buffer size ALWAYS needs to be power of two,
+        this option represents the exponent of 2^n, which will be used as the
+        size of the buffer.
+
+endif # KCONFIG_MODULE_AT

drivers/include/at.h

@@ -54,12 +54,21 @@ extern "C" {
 /**
  * @brief End of line character to send after the AT command.
  */
+#if IS_ACTIVE(CONFIG_AT_SEND_EOL_WINDOWS)
+#define CONFIG_AT_SEND_EOL   "\r\n"
+#elif IS_ACTIVE(CONFIG_AT_SEND_EOL_UNIX)
+#define CONFIG_AT_SEND_EOL   "\n"
+#elif IS_ACTIVE(CONFIG_AT_SEND_EOL_MAC)
+#define CONFIG_AT_SEND_EOL   "\r"
+#endif
+
 #ifndef CONFIG_AT_SEND_EOL
 #define CONFIG_AT_SEND_EOL "\r"
 #endif
 
 /**
- * @brief Disable echo after an AT command is sent.
+ * @brief Enable this to disable check for echo after an AT
+ * command is sent.
  */
 #ifdef DOXYGEN
 #define CONFIG_AT_SEND_SKIP_ECHO
@@ -107,15 +116,28 @@ extern "C" {
 #define CONFIG_AT_RECV_ERROR "ERROR"
 #endif
 
-/**
- * @brief Internal buffer size used to process unsolicited result code data.
- */
 #if defined(MODULE_AT_URC) || DOXYGEN
-#ifndef AT_BUF_SIZE
-#define AT_BUF_SIZE (128)
+
+/**
+ * @brief   Default buffer size used to process unsolicited result code data.
+ *          (as exponent of 2^n).
+ *
+ *          As the buffer size ALWAYS needs to be power of two, this option
+ *          represents the exponent of 2^n, which will be used as the size of
+ *          the buffer.
+ */
+#ifndef CONFIG_AT_BUF_SIZE_EXP
+#define CONFIG_AT_BUF_SIZE_EXP (7U)
 #endif
 /** @} */
 
+/**
+ * @brief   Size of buffer used to process unsolicited result code data.
+ */
+#ifndef AT_BUF_SIZE
+#define AT_BUF_SIZE   (1 << CONFIG_AT_BUF_SIZE_EXP)
+#endif
+
 /**
  * @brief   Unsolicited result code callback
  *