5 files changed, 82 insertions, 2 deletions
diff --git a/src/generic/gpio.h b/src/generic/gpio.h
index 4b5dc812..1b649cab 100644
--- a/src/generic/gpio.h
+++ b/src/generic/gpio.h
@@ -1,7 +1,7 @@
 #ifndef __GENERIC_GPIO_H
 #define __GENERIC_GPIO_H
 
-#include <stdint.h>
+#include <stdint.h> // uint8_t
 
 struct gpio_out {
     uint8_t pin;
diff --git a/src/linux/Kconfig b/src/linux/Kconfig
index b80ca3a7..651f0874 100644
--- a/src/linux/Kconfig
+++ b/src/linux/Kconfig
@@ -3,6 +3,11 @@
 
 if MACH_LINUX
 
+config LINUX_SELECT
+    bool
+    default y
+    select HAVE_GPIO_ADC
+
 config BOARD_DIRECTORY
     string
     default "linux"
diff --git a/src/linux/Makefile b/src/linux/Makefile
index 6d432d15..5ab3fc27 100644
--- a/src/linux/Makefile
+++ b/src/linux/Makefile
@@ -3,7 +3,7 @@
 dirs-y += src/linux src/generic
 
 src-y += linux/main.c linux/timer.c linux/console.c linux/watchdog.c
-src-y += linux/pca9685.c linux/spidev.c
+src-y += linux/pca9685.c linux/spidev.c linux/analog.c
 src-y += generic/crc16_ccitt.c generic/alloc.c
 
 CFLAGS_klipper.elf += -lutil
diff --git a/src/linux/analog.c b/src/linux/analog.c
new file mode 100644
index 00000000..88adc9dd
--- /dev/null
+++ b/src/linux/analog.c
@@ -0,0 +1,61 @@
+// Read analog values from Linux IIO device
+//
+// Copyright (C) 2017  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include <fcntl.h> // open
+#include <stdio.h> // snprintf
+#include <stdlib.h> // atoi
+#include <unistd.h> // read
+#include "command.h" // shutdown
+#include "gpio.h" // gpio_adc_setup
+#include "internal.h" // report_errno
+#include "sched.h" // sched_shutdown
+
+DECL_CONSTANT(ADC_MAX, 4095); // Assume 12bit adc
+
+#define IIO_PATH "/sys/bus/iio/devices/iio:device0/in_voltage%d_raw"
+
+struct gpio_adc
+gpio_adc_setup(uint8_t pin)
+{
+    char fname[256];
+    snprintf(fname, sizeof(fname), IIO_PATH, pin);
+
+    int fd = open(fname, O_RDONLY|O_CLOEXEC);
+    if (fd < 0) {
+        report_errno("analog open", fd);
+        shutdown("Unable to open adc path");
+    }
+    int ret = set_non_blocking(fd);
+    if (ret < 0) {
+        report_errno("analog set_non_blocking", ret);
+        shutdown("Unable to set non blocking on adc path");
+    }
+    return (struct gpio_adc){ .fd = fd };
+}
+
+uint32_t
+gpio_adc_sample(struct gpio_adc g)
+{
+    return 0;
+}
+
+uint16_t
+gpio_adc_read(struct gpio_adc g)
+{
+    char buf[64];
+    int ret = pread(g.fd, buf, sizeof(buf)-1, 0);
+    if (ret <= 0) {
+        report_errno("analog read", ret);
+        shutdown("Error on analog read");
+    }
+    buf[ret] = '\0';
+    return atoi(buf);
+}
+
+void
+gpio_adc_cancel_sample(struct gpio_adc g)
+{
+}
diff --git a/src/linux/gpio.h b/src/linux/gpio.h
new file mode 100644
index 00000000..a2c92520
--- /dev/null
+++ b/src/linux/gpio.h
@@ -0,0 +1,14 @@
+#ifndef __LINUX_GPIO_H
+#define __LINUX_GPIO_H
+
+#include <stdint.h> // uint8_t
+
+struct gpio_adc {
+    int fd;
+};
+struct gpio_adc gpio_adc_setup(uint8_t pin);
+uint32_t gpio_adc_sample(struct gpio_adc g);
+uint16_t gpio_adc_read(struct gpio_adc g);
+void gpio_adc_cancel_sample(struct gpio_adc g);
+
+#endif // gpio.h