Exposing the value of the field as is.
The Peak Current value has to be interpreted as described
in Table 6-10 (Fixed Power Source Peak Current Capability)
of the USB Power Delivery Specification, but that
interpretation will be done in user space, not in kernel.
Suggested-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
---
v3: There was something wrong with my reStructuredText style table. While
attempting to fix it, I realised that in the latest USB PD specification
there are some small changes in the Table 6-10, so I'm skipping that table
from the documentation, and just giving a general explanation for the sysfs
file instead.
I took the liberty of including Reviewed-by tag from Guenter in any case.
The code has not changed.
---
.../ABI/testing/sysfs-class-usb_power_delivery | 7 +++++++
drivers/usb/typec/pd.c | 10 ++++------
include/linux/usb/pd.h | 1 +
3 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-class-usb_power_delivery b/Documentation/ABI/testing/sysfs-class-usb_power_delivery
index 1bf9d1d7902c..61d233c320ea 100644
--- a/Documentation/ABI/testing/sysfs-class-usb_power_delivery
+++ b/Documentation/ABI/testing/sysfs-class-usb_power_delivery
@@ -124,6 +124,13 @@ Contact: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
Description:
The voltage the supply supports in millivolts.
+What: /sys/class/usb_power_delivery/.../source-capabilities/<position>:fixed_supply/peak_current
+Date: October 2023
+Contact: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
+Description:
+ This file shows the value of the Fixed Power Source Peak Current
+ Capability field.
+
What: /sys/class/usb_power_delivery/.../source-capabilities/<position>:fixed_supply/maximum_current
Date: May 2022
Contact: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
diff --git a/drivers/usb/typec/pd.c b/drivers/usb/typec/pd.c
index 8cc66e4467c4..85d015cdbe1f 100644
--- a/drivers/usb/typec/pd.c
+++ b/drivers/usb/typec/pd.c
@@ -83,14 +83,12 @@ unchunked_extended_messages_supported_show(struct device *dev,
}
static DEVICE_ATTR_RO(unchunked_extended_messages_supported);
-/*
- * REVISIT: Peak Current requires access also to the RDO.
static ssize_t
peak_current_show(struct device *dev, struct device_attribute *attr, char *buf)
{
- ...
+ return sysfs_emit(buf, "%u\n", (to_pdo(dev)->pdo >> PDO_FIXED_PEAK_CURR_SHIFT) & 3);
}
-*/
+static DEVICE_ATTR_RO(peak_current);
static ssize_t
fast_role_swap_current_show(struct device *dev, struct device_attribute *attr, char *buf)
@@ -135,7 +133,7 @@ static struct attribute *source_fixed_supply_attrs[] = {
&dev_attr_usb_communication_capable.attr,
&dev_attr_dual_role_data.attr,
&dev_attr_unchunked_extended_messages_supported.attr,
- /*&dev_attr_peak_current.attr,*/
+ &dev_attr_peak_current.attr,
&dev_attr_voltage.attr,
&maximum_current_attr.attr,
NULL
@@ -144,7 +142,7 @@ static struct attribute *source_fixed_supply_attrs[] = {
static umode_t fixed_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n)
{
if (to_pdo(kobj_to_dev(kobj))->object_position &&
- /*attr != &dev_attr_peak_current.attr &&*/
+ attr != &dev_attr_peak_current.attr &&
attr != &dev_attr_voltage.attr &&
attr != &maximum_current_attr.attr &&
attr != &operational_current_attr.attr)
diff --git a/include/linux/usb/pd.h b/include/linux/usb/pd.h
index c59fb79a42e8..eb626af0e4e7 100644
--- a/include/linux/usb/pd.h
+++ b/include/linux/usb/pd.h
@@ -228,6 +228,7 @@ enum pd_pdo_type {
#define PDO_FIXED_UNCHUNK_EXT BIT(24) /* Unchunked Extended Message supported (Source) */
#define PDO_FIXED_FRS_CURR_MASK (BIT(24) | BIT(23)) /* FR_Swap Current (Sink) */
#define PDO_FIXED_FRS_CURR_SHIFT 23
+#define PDO_FIXED_PEAK_CURR_SHIFT 20
#define PDO_FIXED_VOLT_SHIFT 10 /* 50mV units */
#define PDO_FIXED_CURR_SHIFT 0 /* 10mA units */
--
2.40.1
