From b9c83da8c61859996ac287150407d640fe48d208 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADctor=20Mayoral=20Vilches?= <victor@erlerobot.com>
Date: Thu, 7 Jan 2016 19:22:50 +0100
Subject: [PATCH] HAL_Linux: AnalogIn_IIO, replace reopen by select

A new select_pin method has been implemented and
set that changes solely the file descriptor (avoids
reopening the file every time we call set_pin).
---
 libraries/AP_HAL_Linux/AnalogIn_IIO.cpp | 16 ++++++++++++++--
 libraries/AP_HAL_Linux/AnalogIn_IIO.h   |  3 ++-
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/libraries/AP_HAL_Linux/AnalogIn_IIO.cpp b/libraries/AP_HAL_Linux/AnalogIn_IIO.cpp
index 752409ba6e..379395b524 100644
--- a/libraries/AP_HAL_Linux/AnalogIn_IIO.cpp
+++ b/libraries/AP_HAL_Linux/AnalogIn_IIO.cpp
@@ -30,7 +30,8 @@ IIOAnalogSource::IIOAnalogSource(int16_t pin, float initial_value) :
     _sum_count(0),
     _pin_fd(-1)
 {
-    reopen_pin();
+    init_pins();
+    select_pin();    
 }
 
 void IIOAnalogSource::init_pins(void)
@@ -48,6 +49,17 @@ void IIOAnalogSource::init_pins(void)
     }
 }
 
+/*
+  selects a diferent file descriptor among in the fd_analog_sources array
+ */
+void IIOAnalogSource::select_pin(void)
+{
+    _pin_fd = fd_analog_sources[_pin];
+}
+
+/*
+  reopens an analog source (by closing and opening it again)
+ */
 void IIOAnalogSource::reopen_pin(void)
 {
     char buf[100];
@@ -139,7 +151,7 @@ void IIOAnalogSource::set_pin(uint8_t pin)
     _sum_count = 0;
     _latest = 0;
     _value = 0;    
-    reopen_pin();
+    select_pin();
     // _value_ratiometric = 0;
     hal.scheduler->resume_timer_procs();
 }
diff --git a/libraries/AP_HAL_Linux/AnalogIn_IIO.h b/libraries/AP_HAL_Linux/AnalogIn_IIO.h
index 6bdcfd4699..3767c61ddf 100644
--- a/libraries/AP_HAL_Linux/AnalogIn_IIO.h
+++ b/libraries/AP_HAL_Linux/AnalogIn_IIO.h
@@ -42,12 +42,13 @@ private:
     uint8_t     _sum_count;
     int16_t     _pin;
     int         _pin_fd;    
+    int         fd_analog_sources[IIO_ANALOG_IN_COUNT];
 
     void reopen_pin(void);
     void init_pins(void);
+    void select_pin(void);
 
     static const char *analog_sources[IIO_ANALOG_IN_COUNT];
-    static int fd_analog_sources[IIO_ANALOG_IN_COUNT];
 };
 
 class IIOAnalogIn : public AP_HAL::AnalogIn {