sched_ext: Maintain an online cid mask in the scheduler arenagrafted

Schedulers on the default cid mapping treat [0, nr_online_cids) as the
online set and restart on hotplug. Schedulers that install their own mapping
with scx_bpf_cid_override() have no way to learn which cids are online: the
count no longer identifies members and the CPU-form cpumask is unusable from
cid programs. This is an obvious hole in the cid API.

Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's
arena, allocated alongside the per-CPU scratch masks and populated after the
cid mapping is finalized and before ops.init(), for child schedulers too.
The pointer stays valid through ops.exit() with no reference to take. It is
the arena offset as a void pointer, the same form struct_ops arena arguments
arrive in. The verifier types the void return as a scalar for the program's
arena cast.

The mask follows the SCX hotplug notifications: seeded from cpu_active_mask
and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask
only inside a hotplug transition. Updates walk the scheduler list under the
lock that also serializes unlinking. Reads are live, not atomic snapshots.
Root initialization excludes hotplug.

v2: Reworded the getter kerneldoc (Andrea Righi).

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>

1 files changed, 104 insertions, 0 deletions

diff --git a/sound/soc/sof/sof-of-dev.c b/sound/soc/sof/sof-of-dev.c
new file mode 100644
index 000000000..3ccfcfb14
--- /dev/null
+++ b/sound/soc/sof/sof-of-dev.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause)
+//
+// Copyright 2019 NXP
+//
+// Author: Daniel Baluta <daniel.baluta@nxp.com>
+//
+
+#include <linux/firmware.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/pm_runtime.h>
+#include <sound/sof.h>
+
+#include "sof-of-dev.h"
+#include "ops.h"
+
+static char *fw_path;
+module_param(fw_path, charp, 0444);
+MODULE_PARM_DESC(fw_path, "deprecated - moved to snd-sof module.");
+
+static char *fw_filename;
+module_param(fw_filename, charp, 0444);
+MODULE_PARM_DESC(fw_filename, "deprecated - moved to snd-sof module.");
+
+static char *tplg_path;
+module_param(tplg_path, charp, 0444);
+MODULE_PARM_DESC(tplg_path, "deprecated - moved to snd-sof module.");
+
+static char *tplg_filename;
+module_param(tplg_filename, charp, 0444);
+MODULE_PARM_DESC(tplg_filename, "deprecated - moved to snd-sof module.");
+
+EXPORT_DEV_PM_OPS(sof_of_pm) = {
+	.prepare = snd_sof_prepare,
+	.complete = snd_sof_complete,
+	SYSTEM_SLEEP_PM_OPS(snd_sof_suspend, snd_sof_resume)
+	RUNTIME_PM_OPS(snd_sof_runtime_suspend, snd_sof_runtime_resume, NULL)
+};
+
+static void sof_of_probe_complete(struct device *dev)
+{
+	/* allow runtime_pm */
+	pm_runtime_set_autosuspend_delay(dev, SND_SOF_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+}
+
+int sof_of_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct sof_dev_desc *desc;
+	struct snd_sof_pdata *sof_pdata;
+
+	dev_info(&pdev->dev, "DT DSP detected");
+
+	sof_pdata = devm_kzalloc(dev, sizeof(*sof_pdata), GFP_KERNEL);
+	if (!sof_pdata)
+		return -ENOMEM;
+
+	desc = device_get_match_data(dev);
+	if (!desc)
+		return -ENODEV;
+
+	if (!desc->ops) {
+		dev_err(dev, "error: no matching DT descriptor ops\n");
+		return -ENODEV;
+	}
+
+	sof_pdata->desc = desc;
+	sof_pdata->dev = &pdev->dev;
+
+	sof_pdata->ipc_file_profile_base.ipc_type = desc->ipc_default;
+	sof_pdata->ipc_file_profile_base.fw_path = fw_path;
+	sof_pdata->ipc_file_profile_base.tplg_path = tplg_path;
+	sof_pdata->ipc_file_profile_base.fw_name = fw_filename;
+	sof_pdata->ipc_file_profile_base.tplg_name = tplg_filename;
+
+	/* set callback to be called on successful device probe to enable runtime_pm */
+	sof_pdata->sof_probe_complete = sof_of_probe_complete;
+
+	/* call sof helper for DSP hardware probe */
+	return snd_sof_device_probe(dev, sof_pdata);
+}
+EXPORT_SYMBOL(sof_of_probe);
+
+void sof_of_remove(struct platform_device *pdev)
+{
+	pm_runtime_disable(&pdev->dev);
+
+	/* call sof helper for DSP hardware remove */
+	snd_sof_device_remove(&pdev->dev);
+}
+EXPORT_SYMBOL(sof_of_remove);
+
+void sof_of_shutdown(struct platform_device *pdev)
+{
+	snd_sof_device_shutdown(&pdev->dev);
+}
+EXPORT_SYMBOL(sof_of_shutdown);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION("SOF support for OF/DT platforms");