Change permissions and update README

2 files changed, 16 insertions, 5 deletions

diff --git a/README.md b/README.md
index 67d37e6..055c7e1 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,23 @@
 # INA260-sysfs-driver
 
+Link to the [ina260 datasheet](https://www.ti.com/lit/gpn/INA260).
+
 ## Installation
     
     $ make
     $ sudo insmod ina260.ko
 
-## Usage
+## Managing INA260 devices
+- Add device: `echo ina260 [devaddr] > /sys/bus/i2c/devices/<bus>/new_device`
+- Delete device: `echo [devaddr] > /sys/bus/i2c/devices/<bus>/delete_device`
+
+## Sysfs structure
+- Overview: `tree /sys/kernel/ina260`
+- You can access to each device registers in `/sys/kernel/ina260/<device>/registers/`
+- You can access to each device register fields in `/sys/kernel/ina260/<device>/fields/`
+- You can access to the currently measured current, voltage and power via `/sys/kernel/ina260/<device>/<power|current|voltage>` (units are watts, amperes and volts respectively)
 
-- Add device: `echo ina260 <devaddr> > /sys/bus/i2c/devices/<busid>/new_device`
+For more informations on the registers/fields, please refer to the [ina260 datasheet](https://www.ti.com/lit/gpn/INA260).
 
-- Next, run: `tree /sys/kernel/ina260`
\ No newline at end of file
+## Notes
+- Tested so far on a [Beaglebone Black](https://www.beagleboard.org/boards/beaglebone-black) with a [Mikrobus Cape](https://www.mikroe.com/beaglebone-mikrobus-cape) with up to four ina260 devices attached.
\ No newline at end of file
diff --git a/ina260.c b/ina260.c
index 8a99b2e..283757c 100644
--- a/ina260.c
+++ b/ina260.c
@@ -371,9 +371,9 @@ static const struct attribute_group registers_group = {
 };
 // ----- Metrics -----
 static struct kobj_attribute metric_power_attribute =
-    __ATTR(power, 0664, attr_metric_show, NULL);
+    __ATTR(power, 0444, attr_metric_show, NULL);
 static struct kobj_attribute metric_voltage_attribute =
-    __ATTR(voltage, 0664, attr_metric_show, NULL);
+    __ATTR(voltage, 0444, attr_metric_show, NULL);
 static struct kobj_attribute metric_current_attribute = {
 	.attr = {.name = "current", // current is a defined macro so need to do it manually
 		 .mode = VERIFY_OCTAL_PERMISSIONS(0444) },