usb: pd: Exposing the Peak Current value of Fixed Supplies to user space

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@interlog.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20231002142240.2641962-1-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/testing/sysfs-class-usb_power_delivery b/Documentation/ABI/testing/sysfs-class-usb_power_delivery
index 1bf9d1d7902ce4e93ee296ecc057dbedf9ae25b8..61d233c320ea7f6e2e81890f166c89f65e9b0e84 100644 (file)
--- 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@linux.intel.com>
 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@linux.intel.com>
+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@linux.intel.com>

diff --git a/drivers/usb/typec/pd.c b/drivers/usb/typec/pd.c
index 8cc66e4467c48f3f6175f612092c661b484a44e0..85d015cdbe1fe1b530720ae34bdddf08dae10929 100644 (file)
--- 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 c59fb79a42e8672111c0f146c8d535c04c395777..eb626af0e4e7cfc739842a34736317688ac88187 100644 (file)
--- 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 */