Nodes marked with this (boolean) property will have a writable status
sysfs file, which can be used to toggle them between "okay" and
"reserved", effectively hot-plugging them. Note that this will only
be effective for devices on busses that register for OF reconfig
notifications (currently spi, i2c, and platform), and only if
CONFIG_OF_DYNAMIC is enabled.
Signed-off-by: Zev Weiss <zev@xxxxxxxxxxxxxxxxx>
---
drivers/of/kobj.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 69 insertions(+)
diff --git a/drivers/of/kobj.c b/drivers/of/kobj.c
index 378cb421aae1..141ae23f3130 100644
--- a/drivers/of/kobj.c
+++ b/drivers/of/kobj.c
@@ -36,6 +36,69 @@ static ssize_t of_node_property_read(struct file *filp, struct kobject *kobj,
return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length);
}
+static ssize_t of_node_status_write(struct file *filp, struct kobject *kobj,
+ struct bin_attribute *bin_attr, char *buf,
+ loff_t offset, size_t count)
+{
+ int rc;
+ char *newstatus;
+ struct property **deadprev;
+ struct property *newprop = NULL;
+ struct property *oldprop = container_of(bin_attr, struct property, attr);
+ struct device_node *np = container_of(kobj, struct device_node, kobj);
+
+ if (WARN_ON_ONCE(strcmp(oldprop->name, "status")))
+ return -EIO;
+
+ if (offset)
+ return -EINVAL;
+
+ if (sysfs_buf_streq(buf, count, "okay") || sysfs_buf_streq(buf, count, "ok"))
+ newstatus = "okay";
+ else if (sysfs_buf_streq(buf, count, "reserved"))
+ newstatus = "reserved";
+ else if (sysfs_buf_streq(buf, count, "disabled"))
+ newstatus = "disabled";
+ else
+ return -EINVAL;
+
+ if (!strcmp(newstatus, oldprop->value))
+ return count;
+
+ /*
+ * of_update_property_self() doesn't free replaced properties, so
+ * rifle through deadprops first to see if there's an equivalent old
+ * status property we can reuse instead of allocating a new one.
+ */
+ mutex_lock(&of_mutex);
+ for (deadprev = &np->deadprops; *deadprev; deadprev = &(*deadprev)->next) {
+ struct property *deadprop = *deadprev;
+ if (!strcmp(deadprop->name, "status") &&
+ deadprop->length == strlen(newstatus) + 1 &&
+ !strcmp(deadprop->value, newstatus)) {
+ *deadprev = deadprop->next;
+ deadprop->next = NULL;
+ newprop = deadprop;
+ break;
+ }
+ }
+ mutex_unlock(&of_mutex);
+
+ if (!newprop) {
+ newprop = kzalloc(sizeof(*newprop), GFP_KERNEL);
+ if (!newprop)
+ return -ENOMEM;
+
+ newprop->name = oldprop->name;
+ newprop->value = newstatus;
+ newprop->length = strlen(newstatus) + 1;
+ }
+
+ rc = of_update_property_self(np, newprop, true);
+
+ return rc ? rc : count;
+}
+
/* always return newly allocated name, caller must free after use */
static const char *safe_name(struct kobject *kobj, const char *orig_name)
{
@@ -79,6 +142,12 @@ int __of_add_property_sysfs(struct device_node *np, struct property *pp)
pp->attr.size = secure ? 0 : pp->length;
pp->attr.read = of_node_property_read;
+ if (!strcmp(pp->name, "status") && of_property_read_bool(np, "dynamic")) {
+ pp->attr.attr.mode |= 0200;
+ pp->attr.write = of_node_status_write;
+ pp->attr.growable = true;
+ }
+
rc = sysfs_create_bin_file(&np->kobj, &pp->attr);
WARN(rc, "error adding attribute %s to node %pOF\n", pp->name, np);
return rc;
--
2.33.0
