hwmon: (ltc4245) Expose all GPIO pins as analog voltages

Add support for exposing all GPIO pins as analog voltages. Though this is
not an ideal use of the chip, some hardware engineers may decide that the
LTC4245 meets their design requirements when studying the datasheet.

The GPIO pins are sampled in round-robin fashion, meaning that a slow
reader will see stale data. A userspace application can detect this,
because it will get -EAGAIN when reading from a sysfs file which contains
stale data.

Users can choose to use this feature on a per-chip basis by using either
platform data or the OF device tree (where applicable).

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/i2c/ltc4245.h b/include/linux/i2c/ltc4245.h
new file mode 100644
index 000000000000..56bda4be0016
--- /dev/null
+++ b/include/linux/i2c/ltc4245.h
@@ -0,0 +1,21 @@
+/*
+ * Platform Data for LTC4245 hardware monitor chip
+ *
+ * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#ifndef LINUX_LTC4245_H
+#define LINUX_LTC4245_H
+
+#include <linux/types.h>
+
+struct ltc4245_platform_data {
+	bool use_extra_gpios;
+};
+
+#endif /* LINUX_LTC4245_H */