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, 411 insertions, 0 deletions

diff --git a/sound/soc/codecs/framer-codec.c b/sound/soc/codecs/framer-codec.c
new file mode 100644
index 000000000..a87a78390
--- /dev/null
+++ b/sound/soc/codecs/framer-codec.c
@@ -0,0 +1,411 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Framer ALSA SoC driver
+//
+// Copyright 2023 CS GROUP France
+//
+// Author: Herve Codina <herve.codina@bootlin.com>
+
+#include <linux/clk.h>
+#include <linux/framer/framer.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <sound/jack.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/tlv.h>
+
+#define FRAMER_NB_CHANNEL	32
+#define FRAMER_JACK_MASK (SND_JACK_LINEIN | SND_JACK_LINEOUT)
+
+struct framer_codec {
+	struct framer *framer;
+	struct device *dev;
+	struct snd_soc_jack jack;
+	struct notifier_block nb;
+	struct work_struct carrier_work;
+	int max_chan_playback;
+	int max_chan_capture;
+};
+
+static int framer_dai_set_tdm_slot(struct snd_soc_dai *dai, unsigned int tx_mask,
+				   unsigned int rx_mask, int slots, int width)
+{
+	struct framer_codec *framer = snd_soc_component_get_drvdata(dai->component);
+
+	switch (width) {
+	case 0:
+		/* Not set -> default 8 */
+	case 8:
+		break;
+	default:
+		dev_err(dai->dev, "tdm slot width %d not supported\n", width);
+		return -EINVAL;
+	}
+
+	framer->max_chan_playback = hweight32(tx_mask);
+	if (framer->max_chan_playback > FRAMER_NB_CHANNEL) {
+		dev_err(dai->dev, "too many tx slots defined (mask = 0x%x) supported max %d\n",
+			tx_mask, FRAMER_NB_CHANNEL);
+		return -EINVAL;
+	}
+
+	framer->max_chan_capture = hweight32(rx_mask);
+	if (framer->max_chan_capture > FRAMER_NB_CHANNEL) {
+		dev_err(dai->dev, "too many rx slots defined (mask = 0x%x) supported max %d\n",
+			rx_mask, FRAMER_NB_CHANNEL);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * The constraints for format/channel is to match with the number of 8bit
+ * time-slots available.
+ */
+static int framer_dai_hw_rule_channels_by_format(struct snd_soc_dai *dai,
+						 struct snd_pcm_hw_params *params,
+						 unsigned int nb_ts)
+{
+	struct snd_interval *c = hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS);
+	snd_pcm_format_t format = params_format(params);
+	struct snd_interval ch = {0};
+	int width;
+
+	width = snd_pcm_format_physical_width(format);
+	if (width == 8 || width == 16 || width == 32 || width == 64) {
+		ch.max = nb_ts * 8 / width;
+	} else {
+		dev_err(dai->dev, "format physical width %d not supported\n", width);
+		return -EINVAL;
+	}
+
+	ch.min = ch.max ? 1 : 0;
+
+	return snd_interval_refine(c, &ch);
+}
+
+static int framer_dai_hw_rule_playback_channels_by_format(struct snd_pcm_hw_params *params,
+							  struct snd_pcm_hw_rule *rule)
+{
+	struct snd_soc_dai *dai = rule->private;
+	struct framer_codec *framer = snd_soc_component_get_drvdata(dai->component);
+
+	return framer_dai_hw_rule_channels_by_format(dai, params, framer->max_chan_playback);
+}
+
+static int framer_dai_hw_rule_capture_channels_by_format(struct snd_pcm_hw_params *params,
+							 struct snd_pcm_hw_rule *rule)
+{
+	struct snd_soc_dai *dai = rule->private;
+	struct framer_codec *framer = snd_soc_component_get_drvdata(dai->component);
+
+	return framer_dai_hw_rule_channels_by_format(dai, params, framer->max_chan_capture);
+}
+
+static int framer_dai_hw_rule_format_by_channels(struct snd_soc_dai *dai,
+						 struct snd_pcm_hw_params *params,
+						 unsigned int nb_ts)
+{
+	struct snd_mask *f_old = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
+	unsigned int channels = params_channels(params);
+	unsigned int slot_width;
+	snd_pcm_format_t format;
+	struct snd_mask f_new;
+
+	if (!channels || channels > nb_ts) {
+		dev_err(dai->dev, "channels %u not supported\n", nb_ts);
+		return -EINVAL;
+	}
+
+	slot_width = (nb_ts / channels) * 8;
+
+	snd_mask_none(&f_new);
+	pcm_for_each_format(format) {
+		if (snd_mask_test_format(f_old, format)) {
+			if (snd_pcm_format_physical_width(format) <= slot_width)
+				snd_mask_set_format(&f_new, format);
+		}
+	}
+
+	return snd_mask_refine(f_old, &f_new);
+}
+
+static int framer_dai_hw_rule_playback_format_by_channels(struct snd_pcm_hw_params *params,
+							  struct snd_pcm_hw_rule *rule)
+{
+	struct snd_soc_dai *dai = rule->private;
+	struct framer_codec *framer = snd_soc_component_get_drvdata(dai->component);
+
+	return framer_dai_hw_rule_format_by_channels(dai, params, framer->max_chan_playback);
+}
+
+static int framer_dai_hw_rule_capture_format_by_channels(struct snd_pcm_hw_params *params,
+							 struct snd_pcm_hw_rule *rule)
+{
+	struct snd_soc_dai *dai = rule->private;
+	struct framer_codec *framer = snd_soc_component_get_drvdata(dai->component);
+
+	return framer_dai_hw_rule_format_by_channels(dai, params, framer->max_chan_capture);
+}
+
+static u64 framer_formats(u8 nb_ts)
+{
+	unsigned int format_width;
+	unsigned int chan_width;
+	snd_pcm_format_t format;
+	u64 formats_mask;
+
+	if (!nb_ts)
+		return 0;
+
+	formats_mask = 0;
+	chan_width = nb_ts * 8;
+	pcm_for_each_format(format) {
+		/* Support physical width multiple of 8bit */
+		format_width = snd_pcm_format_physical_width(format);
+		if (format_width == 0 || format_width % 8)
+			continue;
+
+		/*
+		 * And support physical width that can fit N times in the
+		 * channel
+		 */
+		if (format_width > chan_width || chan_width % format_width)
+			continue;
+
+		formats_mask |= pcm_format_to_bits(format);
+	}
+	return formats_mask;
+}
+
+static int framer_dai_startup(struct snd_pcm_substream *substream,
+			      struct snd_soc_dai *dai)
+{
+	struct framer_codec *framer = snd_soc_component_get_drvdata(dai->component);
+	snd_pcm_hw_rule_func_t hw_rule_channels_by_format;
+	snd_pcm_hw_rule_func_t hw_rule_format_by_channels;
+	unsigned int frame_bits;
+	u64 format;
+	int ret;
+
+	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
+		format = framer_formats(framer->max_chan_capture);
+		hw_rule_channels_by_format = framer_dai_hw_rule_capture_channels_by_format;
+		hw_rule_format_by_channels = framer_dai_hw_rule_capture_format_by_channels;
+		frame_bits = framer->max_chan_capture * 8;
+	} else {
+		format = framer_formats(framer->max_chan_playback);
+		hw_rule_channels_by_format = framer_dai_hw_rule_playback_channels_by_format;
+		hw_rule_format_by_channels = framer_dai_hw_rule_playback_format_by_channels;
+		frame_bits = framer->max_chan_playback * 8;
+	}
+
+	ret = snd_pcm_hw_constraint_mask64(substream->runtime,
+					   SNDRV_PCM_HW_PARAM_FORMAT, format);
+	if (ret) {
+		dev_err(dai->dev, "Failed to add format constraint (%d)\n", ret);
+		return ret;
+	}
+
+	ret = snd_pcm_hw_rule_add(substream->runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
+				  hw_rule_channels_by_format, dai,
+				  SNDRV_PCM_HW_PARAM_FORMAT, -1);
+	if (ret) {
+		dev_err(dai->dev, "Failed to add channels rule (%d)\n", ret);
+		return ret;
+	}
+
+	ret = snd_pcm_hw_rule_add(substream->runtime, 0,  SNDRV_PCM_HW_PARAM_FORMAT,
+				  hw_rule_format_by_channels, dai,
+				  SNDRV_PCM_HW_PARAM_CHANNELS, -1);
+	if (ret) {
+		dev_err(dai->dev, "Failed to add format rule (%d)\n", ret);
+		return ret;
+	}
+
+	ret = snd_pcm_hw_constraint_single(substream->runtime,
+					   SNDRV_PCM_HW_PARAM_FRAME_BITS,
+					   frame_bits);
+	if (ret < 0) {
+		dev_err(dai->dev, "Failed to add frame_bits constraint (%d)\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const u64 framer_dai_formats = SND_SOC_POSSIBLE_DAIFMT_DSP_B;
+
+static const struct snd_soc_dai_ops framer_dai_ops = {
+	.startup	= framer_dai_startup,
+	.set_tdm_slot	= framer_dai_set_tdm_slot,
+	.auto_selectable_formats     = &framer_dai_formats,
+	.num_auto_selectable_formats = 1,
+};
+
+static struct snd_soc_dai_driver framer_dai_driver = {
+	.name = "framer",
+	.playback = {
+		.stream_name = "Playback",
+		.channels_min = 1,
+		.channels_max = FRAMER_NB_CHANNEL,
+		.rates = SNDRV_PCM_RATE_8000,
+		.formats = U64_MAX, /* Will be refined on DAI .startup() */
+	},
+	.capture = {
+		.stream_name = "Capture",
+		.channels_min = 1,
+		.channels_max = FRAMER_NB_CHANNEL,
+		.rates = SNDRV_PCM_RATE_8000,
+		.formats = U64_MAX, /* Will be refined on DAI .startup() */
+	},
+	.ops = &framer_dai_ops,
+};
+
+static void framer_carrier_work(struct work_struct *work)
+{
+	struct framer_codec *framer = container_of(work, struct framer_codec, carrier_work);
+	struct framer_status framer_status;
+	int jack_status;
+	int ret;
+
+	ret = framer_get_status(framer->framer, &framer_status);
+	if (ret) {
+		dev_err(framer->dev, "get framer status failed (%d)\n", ret);
+		return;
+	}
+
+	jack_status = framer_status.link_is_on ? FRAMER_JACK_MASK : 0;
+	snd_soc_jack_report(&framer->jack, jack_status, FRAMER_JACK_MASK);
+}
+
+static int framer_carrier_notifier(struct notifier_block *nb, unsigned long action,
+				   void *data)
+{
+	struct framer_codec *framer = container_of(nb, struct framer_codec, nb);
+
+	switch (action) {
+	case FRAMER_EVENT_STATUS:
+		queue_work(system_power_efficient_wq, &framer->carrier_work);
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static int framer_component_probe(struct snd_soc_component *component)
+{
+	struct framer_codec *framer = snd_soc_component_get_drvdata(component);
+	struct framer_status status;
+	char *name;
+	int ret;
+
+	INIT_WORK(&framer->carrier_work, framer_carrier_work);
+
+	name = "carrier";
+	if (component->name_prefix) {
+		name = kasprintf(GFP_KERNEL, "%s carrier", component->name_prefix);
+		if (!name)
+			return -ENOMEM;
+	}
+
+	ret = snd_soc_card_jack_new(component->card, name, FRAMER_JACK_MASK, &framer->jack);
+	if (component->name_prefix)
+		kfree(name); /* A copy is done by snd_soc_card_jack_new */
+	if (ret) {
+		dev_err(component->dev, "Cannot create jack\n");
+		return ret;
+	}
+
+	ret = framer_init(framer->framer);
+	if (ret) {
+		dev_err(component->dev, "framer init failed (%d)\n", ret);
+		return ret;
+	}
+
+	ret = framer_power_on(framer->framer);
+	if (ret) {
+		dev_err(component->dev, "framer power-on failed (%d)\n", ret);
+		goto framer_exit;
+	}
+
+	/* Be sure that get_status is supported */
+	ret = framer_get_status(framer->framer, &status);
+	if (ret) {
+		dev_err(component->dev, "get framer status failed (%d)\n", ret);
+		goto framer_power_off;
+	}
+
+	framer->nb.notifier_call = framer_carrier_notifier;
+	ret = framer_notifier_register(framer->framer, &framer->nb);
+	if (ret) {
+		dev_err(component->dev, "Cannot register event notifier\n");
+		goto framer_power_off;
+	}
+
+	/* Queue work to set the initial value */
+	queue_work(system_power_efficient_wq, &framer->carrier_work);
+
+	return 0;
+
+framer_power_off:
+	framer_power_off(framer->framer);
+framer_exit:
+	framer_exit(framer->framer);
+	return ret;
+}
+
+static void framer_component_remove(struct snd_soc_component *component)
+{
+	struct framer_codec *framer = snd_soc_component_get_drvdata(component);
+
+	framer_notifier_unregister(framer->framer, &framer->nb);
+	cancel_work_sync(&framer->carrier_work);
+	framer_power_off(framer->framer);
+	framer_exit(framer->framer);
+}
+
+static const struct snd_soc_component_driver framer_component_driver = {
+	.probe		= framer_component_probe,
+	.remove		= framer_component_remove,
+	.endianness	= 1,
+};
+
+static int framer_codec_probe(struct platform_device *pdev)
+{
+	struct framer_codec *framer;
+
+	framer = devm_kzalloc(&pdev->dev, sizeof(*framer), GFP_KERNEL);
+	if (!framer)
+		return -ENOMEM;
+
+	framer->dev = &pdev->dev;
+
+	/* Get framer from parents node */
+	framer->framer = devm_framer_get(&pdev->dev, NULL);
+	if (IS_ERR(framer->framer))
+		return dev_err_probe(&pdev->dev, PTR_ERR(framer->framer), "get framer failed\n");
+
+	platform_set_drvdata(pdev, framer);
+
+	return devm_snd_soc_register_component(&pdev->dev, &framer_component_driver,
+					       &framer_dai_driver, 1);
+}
+
+static struct platform_driver framer_codec_driver = {
+	.driver = {
+		.name = "framer-codec",
+	},
+	.probe = framer_codec_probe,
+};
+module_platform_driver(framer_codec_driver);
+
+MODULE_AUTHOR("Herve Codina <herve.codina@bootlin.com>");
+MODULE_DESCRIPTION("FRAMER ALSA SoC driver");
+MODULE_LICENSE("GPL");