net: ipa: add an endpoint device attribute group

Create a new attribute group meant to provide a single place that
defines endpoint IDs that might be needed by user space.  Not all
defined endpoints are presented, and only those that are defined
will be made visible.

The new attributes use "extended" device attributes to hold endpoint
IDs, which is a little more compact and efficient.  Reimplement the
existing modem endpoint ID attribute files using common code.

Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20220719191639.373249-1-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 51 insertions, 18 deletions

diff --git a/drivers/net/ipa/ipa_sysfs.c b/drivers/net/ipa/ipa_sysfs.c
index ff61dbdd70d8..c0c8641cdd14 100644
--- a/drivers/net/ipa/ipa_sysfs.c
+++ b/drivers/net/ipa/ipa_sysfs.c
@@ -96,38 +96,71 @@ const struct attribute_group ipa_feature_attribute_group = {
 	.attrs		= ipa_feature_attrs,
 };
 
-static ssize_t
-ipa_endpoint_id_show(struct ipa *ipa, char *buf, enum ipa_endpoint_name name)
+static umode_t ipa_endpoint_id_is_visible(struct kobject *kobj,
+					  struct attribute *attr, int n)
 {
-	u32 endpoint_id = ipa->name_map[name]->endpoint_id;
+	struct ipa *ipa = dev_get_drvdata(kobj_to_dev(kobj));
+	struct device_attribute *dev_attr;
+	struct dev_ext_attribute *ea;
+	bool visible;
+
+	/* An endpoint id attribute is only visible if it's defined */
+	dev_attr = container_of(attr, struct device_attribute, attr);
+	ea = container_of(dev_attr, struct dev_ext_attribute, attr);
 
-	return scnprintf(buf, PAGE_SIZE, "%u\n", endpoint_id);
+	visible = !!ipa->name_map[(enum ipa_endpoint_name)(uintptr_t)ea->var];
+
+	return visible ? attr->mode : 0;
 }
 
-static ssize_t rx_endpoint_id_show(struct device *dev,
-				   struct device_attribute *attr, char *buf)
+static ssize_t endpoint_id_attr_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
 {
 	struct ipa *ipa = dev_get_drvdata(dev);
+	struct ipa_endpoint *endpoint;
+	struct dev_ext_attribute *ea;
+
+	ea = container_of(attr, struct dev_ext_attribute, attr);
+	endpoint = ipa->name_map[(enum ipa_endpoint_name)(uintptr_t)ea->var];
 
-	return ipa_endpoint_id_show(ipa, buf, IPA_ENDPOINT_AP_MODEM_RX);
+	return sysfs_emit(buf, "%u\n", endpoint->endpoint_id);
 }
 
-static DEVICE_ATTR_RO(rx_endpoint_id);
+#define ENDPOINT_ID_ATTR(_n, _endpoint_name)				    \
+	static struct dev_ext_attribute dev_attr_endpoint_id_ ## _n = {	    \
+		.attr	= __ATTR(_n, 0444, endpoint_id_attr_show, NULL),    \
+		.var	= (void *)(_endpoint_name),			    \
+	}
 
-static ssize_t tx_endpoint_id_show(struct device *dev,
-				   struct device_attribute *attr, char *buf)
-{
-	struct ipa *ipa = dev_get_drvdata(dev);
+ENDPOINT_ID_ATTR(modem_rx, IPA_ENDPOINT_AP_MODEM_RX);
+ENDPOINT_ID_ATTR(modem_tx, IPA_ENDPOINT_AP_MODEM_TX);
 
-	return ipa_endpoint_id_show(ipa, buf, IPA_ENDPOINT_AP_MODEM_TX);
-}
+static struct attribute *ipa_endpoint_id_attrs[] = {
+	&dev_attr_endpoint_id_modem_rx.attr.attr,
+	&dev_attr_endpoint_id_modem_tx.attr.attr,
+	NULL
+};
 
-static DEVICE_ATTR_RO(tx_endpoint_id);
+const struct attribute_group ipa_endpoint_id_attribute_group = {
+	.name		= "endpoint_id",
+	.is_visible	= ipa_endpoint_id_is_visible,
+	.attrs		= ipa_endpoint_id_attrs,
+};
+
+/* Reuse endpoint ID attributes for the legacy modem endpoint IDs */
+#define MODEM_ATTR(_n, _endpoint_name)					    \
+	static struct dev_ext_attribute dev_attr_modem_ ## _n = {	    \
+		.attr	= __ATTR(_n, 0444, endpoint_id_attr_show, NULL),    \
+		.var	= (void *)(_endpoint_name),			    \
+	}
+
+MODEM_ATTR(rx_endpoint_id, IPA_ENDPOINT_AP_MODEM_RX);
+MODEM_ATTR(tx_endpoint_id, IPA_ENDPOINT_AP_MODEM_TX);
 
 static struct attribute *ipa_modem_attrs[] = {
-	&dev_attr_rx_endpoint_id.attr,
-	&dev_attr_tx_endpoint_id.attr,
-	NULL
+	&dev_attr_modem_rx_endpoint_id.attr.attr,
+	&dev_attr_modem_tx_endpoint_id.attr.attr,
+	NULL,
 };
 
 const struct attribute_group ipa_modem_attribute_group = {