pmdomain: Add pm_test_nopop_bus and a driver for sync_state tests
Populate device-nodes under /pm_tests_nopop and hook up a bus/driver to
them.
Use "probe-delay-ms" to delay probe and/or use "probe-defer" to always
return -EPROBE_DEFER from their ->probe().
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/pmdomain/Makefile b/drivers/pmdomain/Makefile
index 314db5a..8533af9 100644
--- a/drivers/pmdomain/Makefile
+++ b/drivers/pmdomain/Makefile
@@ -22,3 +22,4 @@
obj-y += pm_domain_test.o
obj-y += pm_domain_oc_test.o
obj-y += pm_domain_oc_aux_test.o
+obj-y += pm_nopop_bus_test.o
diff --git a/drivers/pmdomain/pm_nopop_bus_test.c b/drivers/pmdomain/pm_nopop_bus_test.c
new file mode 100644
index 0000000..b99b631
--- /dev/null
+++ b/drivers/pmdomain/pm_nopop_bus_test.c
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2025 Linaro Ltd.
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * Implements device node popluation to test consumers getting attached to PM
+ * PM domains in regards to the sync_state mechanism.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/pm_domain.h>
+
+static void __maybe_unused pm_test_nopop_plat_populate(struct device_node *np)
+{
+ int err;
+
+ /*
+ * of_platform_populate() calls of_device_alloc() that creates
+ * a device and assigns its fwnode via device_set_node().
+ * This means the device are taken into account for sync_state.
+ */
+
+ err = of_platform_populate(np, NULL, NULL, NULL);
+ if (err)
+ pr_info("%s: OF populate failed %d\n", __func__, err);
+}
+
+static const struct bus_type pm_test_nopop_bus_type = {
+ .name = "pm_test_nopop_bus",
+};
+
+static int pm_test_nopop_probe(struct device *dev)
+{
+ u32 probe_delay_ms = 0;
+ int ret = 0;
+
+ dev_info(dev, "%s\n", __func__);
+
+ /* DT property to see if we should delay probe. */
+ of_property_read_u32(dev->of_node, "probe-delay-ms", &probe_delay_ms);
+ if (probe_delay_ms) {
+ dev_info(dev, "%s Delaying probe %ums\n", __func__, probe_delay_ms);
+ msleep(probe_delay_ms);
+ }
+
+ /* DT property to see if we should defer probe. */
+ if (of_property_present(dev->of_node, "probe-defer")) {
+ dev_info(dev, "%s Enforce a probe defer\n", __func__);
+ ret = -EPROBE_DEFER;
+ goto out;
+ }
+
+out:
+ dev_info(dev, "%s ret=%d\n", __func__, ret);
+ return ret;
+}
+
+static struct device_driver pm_test_nopop_drv = {
+ .name = "pm_test_nopop_drv",
+ .bus = &pm_test_nopop_bus_type,
+ .probe = pm_test_nopop_probe,
+ .probe_type = PROBE_PREFER_ASYNCHRONOUS,
+};
+
+static void pm_test_nopop_release(struct device *dev) { }
+
+static void __maybe_unused pm_test_nopop_bus_populate(struct device_node *np)
+{
+ struct device *dev;
+ int ret;
+
+ ret = bus_register(&pm_test_nopop_bus_type);
+ if (ret) {
+ pr_info("%s: failed (err %d) to register bus\n", __func__, ret);
+ return;
+ }
+
+ ret = driver_register(&pm_test_nopop_drv);
+ if (ret) {
+ pr_info("%s: failed (err %d) to register drv\n", __func__, ret);
+ return;
+ }
+
+ for_each_child_of_node_scoped(np, node) {
+ struct fwnode_handle *fwnode;
+ const char *name;
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev)
+ return;
+
+ name = kasprintf(GFP_KERNEL, "%pOF", node);
+ name = kbasename(name);
+ dev_set_name(dev, "%s", name);
+ dev->release = pm_test_nopop_release;
+ dev->bus = &pm_test_nopop_bus_type;
+
+ /*
+ * Alone and with the driver being probed later, we need to set
+ * the fwnode for the device, otherwise the device will not be
+ * taken into account in the ->sync_state() condition for the
+ * supplier (the genpd OF provider). In other words, just
+ * setting the OF node as below, is not suffient for
+ * ->sync_state() to work:
+ *
+ * dev->of_node = of_node_get(node);
+ */
+ fwnode = of_fwnode_handle(node);
+ device_set_node(dev, fwnode);
+
+ pr_info("%s: adding dev %s\n", __func__, name);
+
+ ret = device_register(dev);
+ if (ret)
+ pr_info("%s: failed (err %d) to add dev %pOF\n",
+ __func__, ret, node);
+ }
+}
+
+static int __init pm_test_nopop_init(void)
+{
+ struct device_node *np;
+
+ pr_info("%s\n", __func__);
+
+ np = of_find_node_by_path("/pm_tests_nopop");
+ if (!np)
+ return 0;
+
+ /*
+ * If no population of the DT node is node, the node isn't taken into
+ * account at all, which means the ->sync_state() callback of the
+ * supplieris gets invoked.
+ * If population is done, a compatible driver must be probed to allow
+ * the ->sync_state() callback to be invoked.
+ */
+
+#if 0
+ pm_test_nopop_plat_populate(np);
+#else
+ pm_test_nopop_bus_populate(np);
+#endif
+
+ pr_info("%s /pm_tests_nopop node populated\n", __func__);
+ return 0;
+}
+late_initcall(pm_test_nopop_init);
+
+MODULE_LICENSE("GPL v2");
