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, 465 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/imagis.c b/drivers/input/touchscreen/imagis.c
new file mode 100644
index 000000000..7bbb00bee
--- /dev/null
+++ b/drivers/input/touchscreen/imagis.c
@@ -0,0 +1,465 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
+
+#define IST30XX_REG_STATUS		0x20
+#define IST30XX_REG_CHIPID		(0x40000000 | IST3038C_DIRECT_ACCESS)
+
+#define IST30XX_WHOAMI			0x30003000
+#define IST30XXA_WHOAMI			0x300a300a
+#define IST30XXB_WHOAMI			0x300b300b
+#define IST3038_WHOAMI			0x30383038
+
+#define IST3032C_WHOAMI			0x32c
+#define IST3038C_WHOAMI			0x38c
+#define IST3038H_WHOAMI			0x38d
+
+#define IST3038B_REG_CHIPID		0x30
+#define IST3038B_WHOAMI			0x30380b
+
+#define IST3038C_HIB_ACCESS		(0x800B << 16)
+#define IST3038C_DIRECT_ACCESS		BIT(31)
+#define IST3038C_REG_CHIPID		(0x40001000 | IST3038C_DIRECT_ACCESS)
+#define IST3038C_REG_HIB_BASE		0x30000100
+#define IST3038C_REG_TOUCH_STATUS	(IST3038C_REG_HIB_BASE | IST3038C_HIB_ACCESS)
+#define IST3038C_REG_TOUCH_COORD	(IST3038C_REG_HIB_BASE | IST3038C_HIB_ACCESS | 0x8)
+#define IST3038C_REG_INTR_MESSAGE	(IST3038C_REG_HIB_BASE | IST3038C_HIB_ACCESS | 0x4)
+#define IST3038C_CHIP_ON_DELAY_MS	60
+#define IST3038C_I2C_RETRY_COUNT	3
+#define IST3038C_MAX_FINGER_NUM		10
+#define IST3038C_X_MASK			GENMASK(23, 12)
+#define IST3038C_Y_MASK			GENMASK(11, 0)
+#define IST3038C_AREA_MASK		GENMASK(27, 24)
+#define IST3038C_FINGER_COUNT_MASK	GENMASK(15, 12)
+#define IST3038C_FINGER_STATUS_MASK	GENMASK(9, 0)
+#define IST3032C_KEY_STATUS_MASK	GENMASK(20, 16)
+
+struct imagis_properties {
+	unsigned int interrupt_msg_cmd;
+	unsigned int touch_coord_cmd;
+	unsigned int whoami_cmd;
+	unsigned int whoami_val;
+	bool protocol_b;
+	bool touch_keys_supported;
+};
+
+struct imagis_ts {
+	struct i2c_client *client;
+	const struct imagis_properties *tdata;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct regulator_bulk_data supplies[2];
+	u32 keycodes[5];
+	int num_keycodes;
+};
+
+static int imagis_i2c_read_reg(struct imagis_ts *ts,
+			       unsigned int reg, u32 *data)
+{
+	__be32 ret_be;
+	__be32 reg_be = cpu_to_be32(reg);
+	struct i2c_msg msg[] = {
+		{
+			.addr = ts->client->addr,
+			.flags = 0,
+			.buf = (unsigned char *)&reg_be,
+			.len = sizeof(reg_be),
+		}, {
+			.addr = ts->client->addr,
+			.flags = I2C_M_RD,
+			.buf = (unsigned char *)&ret_be,
+			.len = sizeof(ret_be),
+		},
+	};
+	int ret, error;
+	int retry = IST3038C_I2C_RETRY_COUNT;
+
+	/* Retry in case the controller fails to respond */
+	do {
+		ret = i2c_transfer(ts->client->adapter, msg, ARRAY_SIZE(msg));
+		if (ret == ARRAY_SIZE(msg)) {
+			*data = be32_to_cpu(ret_be);
+			return 0;
+		}
+
+		error = ret < 0 ? ret : -EIO;
+		dev_err(&ts->client->dev,
+			"%s - i2c_transfer failed: %d (%d)\n",
+			__func__, error, ret);
+	} while (--retry);
+
+	return error;
+}
+
+static irqreturn_t imagis_interrupt(int irq, void *dev_id)
+{
+	struct imagis_ts *ts = dev_id;
+	u32 intr_message, finger_status;
+	unsigned int finger_count, finger_pressed, key_pressed;
+	int i;
+	int error;
+
+	error = imagis_i2c_read_reg(ts, ts->tdata->interrupt_msg_cmd, &intr_message);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"failed to read the interrupt message: %d\n", error);
+		goto out;
+	}
+
+	finger_count = FIELD_GET(IST3038C_FINGER_COUNT_MASK, intr_message);
+	if (finger_count > IST3038C_MAX_FINGER_NUM) {
+		dev_err(&ts->client->dev,
+			"finger count %d is more than maximum supported\n",
+			finger_count);
+		goto out;
+	}
+
+	finger_pressed = FIELD_GET(IST3038C_FINGER_STATUS_MASK, intr_message);
+
+	for (i = 0; i < finger_count; i++) {
+		if (ts->tdata->protocol_b)
+			error = imagis_i2c_read_reg(ts,
+						    ts->tdata->touch_coord_cmd + (i * 4),
+						    &finger_status);
+		else
+			error = imagis_i2c_read_reg(ts,
+						    ts->tdata->touch_coord_cmd, &finger_status);
+		if (error) {
+			dev_err(&ts->client->dev,
+				"failed to read coordinates for finger %d: %d\n",
+				i, error);
+			goto out;
+		}
+
+		input_mt_slot(ts->input_dev, i);
+		input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER,
+					   finger_pressed & BIT(i));
+		touchscreen_report_pos(ts->input_dev, &ts->prop,
+				       FIELD_GET(IST3038C_X_MASK, finger_status),
+				       FIELD_GET(IST3038C_Y_MASK, finger_status),
+				       true);
+		input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR,
+				 FIELD_GET(IST3038C_AREA_MASK, finger_status));
+	}
+
+	key_pressed = FIELD_GET(IST3032C_KEY_STATUS_MASK, intr_message);
+
+	for (int i = 0; i < ts->num_keycodes; i++)
+		input_report_key(ts->input_dev, ts->keycodes[i],
+				 key_pressed & BIT(i));
+
+	input_mt_sync_frame(ts->input_dev);
+	input_sync(ts->input_dev);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static void imagis_power_off(void *_ts)
+{
+	struct imagis_ts *ts = _ts;
+
+	regulator_bulk_disable(ARRAY_SIZE(ts->supplies), ts->supplies);
+}
+
+static int imagis_power_on(struct imagis_ts *ts)
+{
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(ts->supplies), ts->supplies);
+	if (error)
+		return error;
+
+	msleep(IST3038C_CHIP_ON_DELAY_MS);
+
+	return 0;
+}
+
+static int imagis_start(struct imagis_ts *ts)
+{
+	int error;
+
+	error = imagis_power_on(ts);
+	if (error)
+		return error;
+
+	enable_irq(ts->client->irq);
+
+	return 0;
+}
+
+static int imagis_stop(struct imagis_ts *ts)
+{
+	disable_irq(ts->client->irq);
+
+	imagis_power_off(ts);
+
+	return 0;
+}
+
+static int imagis_input_open(struct input_dev *dev)
+{
+	struct imagis_ts *ts = input_get_drvdata(dev);
+
+	return imagis_start(ts);
+}
+
+static void imagis_input_close(struct input_dev *dev)
+{
+	struct imagis_ts *ts = input_get_drvdata(dev);
+
+	imagis_stop(ts);
+}
+
+static int imagis_init_input_dev(struct imagis_ts *ts)
+{
+	struct input_dev *input_dev;
+	int error;
+
+	input_dev = devm_input_allocate_device(&ts->client->dev);
+	if (!input_dev)
+		return -ENOMEM;
+
+	ts->input_dev = input_dev;
+
+	input_dev->name = "Imagis capacitive touchscreen";
+	input_dev->phys = "input/ts";
+	input_dev->id.bustype = BUS_I2C;
+	input_dev->open = imagis_input_open;
+	input_dev->close = imagis_input_close;
+
+	input_set_drvdata(input_dev, ts);
+
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0, 16, 0, 0);
+	if (ts->tdata->touch_keys_supported) {
+		ts->num_keycodes = of_property_read_variable_u32_array(
+				ts->client->dev.of_node, "linux,keycodes",
+				ts->keycodes, 0, ARRAY_SIZE(ts->keycodes));
+		if (ts->num_keycodes <= 0) {
+			ts->keycodes[0] = KEY_APPSELECT;
+			ts->keycodes[1] = KEY_BACK;
+			ts->num_keycodes = 2;
+		}
+
+		input_dev->keycodemax = ts->num_keycodes;
+		input_dev->keycodesize = sizeof(ts->keycodes[0]);
+		input_dev->keycode = ts->keycodes;
+	}
+
+	for (int i = 0; i < ts->num_keycodes; i++)
+		input_set_capability(input_dev, EV_KEY, ts->keycodes[i]);
+
+	touchscreen_parse_properties(input_dev, true, &ts->prop);
+	if (!ts->prop.max_x || !ts->prop.max_y) {
+		dev_err(&ts->client->dev,
+			"Touchscreen-size-x and/or touchscreen-size-y not set in dts\n");
+		return -EINVAL;
+	}
+
+	error = input_mt_init_slots(input_dev,
+				    IST3038C_MAX_FINGER_NUM,
+				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to initialize MT slots: %d", error);
+		return error;
+	}
+
+	error = input_register_device(input_dev);
+	if (error) {
+		dev_err(&ts->client->dev,
+			"Failed to register input device: %d", error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int imagis_init_regulators(struct imagis_ts *ts)
+{
+	struct i2c_client *client = ts->client;
+
+	ts->supplies[0].supply = "vdd";
+	ts->supplies[1].supply = "vddio";
+	return devm_regulator_bulk_get(&client->dev,
+				       ARRAY_SIZE(ts->supplies),
+				       ts->supplies);
+}
+
+static int imagis_probe(struct i2c_client *i2c)
+{
+	struct device *dev = &i2c->dev;
+	struct imagis_ts *ts;
+	int chip_id, error;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->client = i2c;
+
+	ts->tdata = device_get_match_data(dev);
+	if (!ts->tdata) {
+		dev_err(dev, "missing chip data\n");
+		return -EINVAL;
+	}
+
+	error = imagis_init_regulators(ts);
+	if (error) {
+		dev_err(dev, "regulator init error: %d\n", error);
+		return error;
+	}
+
+	error = imagis_power_on(ts);
+	if (error) {
+		dev_err(dev, "failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	error = devm_add_action_or_reset(dev, imagis_power_off, ts);
+	if (error) {
+		dev_err(dev, "failed to install poweroff action: %d\n", error);
+		return error;
+	}
+
+	error = imagis_i2c_read_reg(ts, ts->tdata->whoami_cmd, &chip_id);
+	if (error) {
+		dev_err(dev, "chip ID read failure: %d\n", error);
+		return error;
+	}
+
+	if (chip_id != ts->tdata->whoami_val) {
+		dev_err(dev, "unknown chip ID: 0x%x\n", chip_id);
+		return -EINVAL;
+	}
+
+	error = devm_request_threaded_irq(dev, i2c->irq,
+					  NULL, imagis_interrupt,
+					  IRQF_ONESHOT | IRQF_NO_AUTOEN,
+					  "imagis-touchscreen", ts);
+	if (error) {
+		dev_err(dev, "IRQ %d allocation failure: %d\n",
+			i2c->irq, error);
+		return error;
+	}
+
+	error = imagis_init_input_dev(ts);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static int imagis_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct imagis_ts *ts = i2c_get_clientdata(client);
+	int error;
+
+	guard(mutex)(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev)) {
+		error = imagis_stop(ts);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+static int imagis_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct imagis_ts *ts = i2c_get_clientdata(client);
+	int error;
+
+	guard(mutex)(&ts->input_dev->mutex);
+
+	if (input_device_enabled(ts->input_dev)) {
+		error = imagis_start(ts);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(imagis_pm_ops, imagis_suspend, imagis_resume);
+
+#ifdef CONFIG_OF
+static const struct imagis_properties imagis_3032c_data = {
+	.interrupt_msg_cmd = IST3038C_REG_INTR_MESSAGE,
+	.touch_coord_cmd = IST3038C_REG_TOUCH_COORD,
+	.whoami_cmd = IST3038C_REG_CHIPID,
+	.whoami_val = IST3032C_WHOAMI,
+	.touch_keys_supported = true,
+	.protocol_b = true,
+};
+
+static const struct imagis_properties imagis_3038_data = {
+	.interrupt_msg_cmd = IST30XX_REG_STATUS,
+	.touch_coord_cmd = IST30XX_REG_STATUS,
+	.whoami_cmd = IST30XX_REG_CHIPID,
+	.whoami_val = IST3038_WHOAMI,
+	.touch_keys_supported = true,
+};
+
+static const struct imagis_properties imagis_3038b_data = {
+	.interrupt_msg_cmd = IST30XX_REG_STATUS,
+	.touch_coord_cmd = IST30XX_REG_STATUS,
+	.whoami_cmd = IST3038B_REG_CHIPID,
+	.whoami_val = IST3038B_WHOAMI,
+};
+
+static const struct imagis_properties imagis_3038c_data = {
+	.interrupt_msg_cmd = IST3038C_REG_INTR_MESSAGE,
+	.touch_coord_cmd = IST3038C_REG_TOUCH_COORD,
+	.whoami_cmd = IST3038C_REG_CHIPID,
+	.whoami_val = IST3038C_WHOAMI,
+	.protocol_b = true,
+};
+
+static const struct imagis_properties imagis_3038h_data = {
+	.interrupt_msg_cmd = IST3038C_REG_INTR_MESSAGE,
+	.touch_coord_cmd = IST3038C_REG_TOUCH_COORD,
+	.whoami_cmd = IST3038C_REG_CHIPID,
+	.whoami_val = IST3038H_WHOAMI,
+};
+
+static const struct of_device_id imagis_of_match[] = {
+	{ .compatible = "imagis,ist3032c", .data = &imagis_3032c_data },
+	{ .compatible = "imagis,ist3038", .data = &imagis_3038_data },
+	{ .compatible = "imagis,ist3038b", .data = &imagis_3038b_data },
+	{ .compatible = "imagis,ist3038c", .data = &imagis_3038c_data },
+	{ .compatible = "imagis,ist3038h", .data = &imagis_3038h_data },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, imagis_of_match);
+#endif
+
+static struct i2c_driver imagis_ts_driver = {
+	.driver = {
+		.name = "imagis-touchscreen",
+		.pm = pm_sleep_ptr(&imagis_pm_ops),
+		.of_match_table = of_match_ptr(imagis_of_match),
+	},
+	.probe = imagis_probe,
+};
+
+module_i2c_driver(imagis_ts_driver);
+
+MODULE_DESCRIPTION("Imagis IST3038C Touchscreen Driver");
+MODULE_AUTHOR("Markuss Broks <markuss.broks@gmail.com>");
+MODULE_LICENSE("GPL");