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, 533 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-max8997.c b/drivers/rtc/rtc-max8997.c
new file mode 100644
index 000000000..89203c92e
--- /dev/null
+++ b/drivers/rtc/rtc-max8997.c
@@ -0,0 +1,533 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// RTC driver for Maxim MAX8997
+//
+// Copyright (C) 2013 Samsung Electronics Co.Ltd
+//
+//  based on rtc-max8998.c
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/max8997-private.h>
+#include <linux/irqdomain.h>
+
+/* Module parameter for WTSR function control */
+static int wtsr_en = 1;
+module_param(wtsr_en, int, 0444);
+MODULE_PARM_DESC(wtsr_en, "Watchdog Timeout & Software Reset (default=on)");
+/* Module parameter for SMPL function control */
+static int smpl_en = 1;
+module_param(smpl_en, int, 0444);
+MODULE_PARM_DESC(smpl_en, "Sudden Momentary Power Loss (default=on)");
+
+/* RTC Control Register */
+#define BCD_EN_SHIFT			0
+#define BCD_EN_MASK			(1 << BCD_EN_SHIFT)
+#define MODEL24_SHIFT			1
+#define MODEL24_MASK			(1 << MODEL24_SHIFT)
+/* RTC Update Register1 */
+#define RTC_UDR_SHIFT			0
+#define RTC_UDR_MASK			(1 << RTC_UDR_SHIFT)
+/* WTSR and SMPL Register */
+#define WTSRT_SHIFT			0
+#define SMPLT_SHIFT			2
+#define WTSR_EN_SHIFT			6
+#define SMPL_EN_SHIFT			7
+#define WTSRT_MASK			(3 << WTSRT_SHIFT)
+#define SMPLT_MASK			(3 << SMPLT_SHIFT)
+#define WTSR_EN_MASK			(1 << WTSR_EN_SHIFT)
+#define SMPL_EN_MASK			(1 << SMPL_EN_SHIFT)
+/* RTC Hour register */
+#define HOUR_PM_SHIFT			6
+#define HOUR_PM_MASK			(1 << HOUR_PM_SHIFT)
+/* RTC Alarm Enable */
+#define ALARM_ENABLE_SHIFT		7
+#define ALARM_ENABLE_MASK		(1 << ALARM_ENABLE_SHIFT)
+
+enum {
+	RTC_SEC = 0,
+	RTC_MIN,
+	RTC_HOUR,
+	RTC_WEEKDAY,
+	RTC_MONTH,
+	RTC_YEAR,
+	RTC_DATE,
+	RTC_NR_TIME
+};
+
+struct max8997_rtc_info {
+	struct device		*dev;
+	struct max8997_dev	*max8997;
+	struct i2c_client	*rtc;
+	struct rtc_device	*rtc_dev;
+	struct mutex		lock;
+	int virq;
+	int rtc_24hr_mode;
+};
+
+static void max8997_rtc_data_to_tm(u8 *data, struct rtc_time *tm,
+				   int rtc_24hr_mode)
+{
+	tm->tm_sec = data[RTC_SEC] & 0x7f;
+	tm->tm_min = data[RTC_MIN] & 0x7f;
+	if (rtc_24hr_mode)
+		tm->tm_hour = data[RTC_HOUR] & 0x1f;
+	else {
+		tm->tm_hour = data[RTC_HOUR] & 0x0f;
+		if (data[RTC_HOUR] & HOUR_PM_MASK)
+			tm->tm_hour += 12;
+	}
+
+	tm->tm_wday = fls(data[RTC_WEEKDAY] & 0x7f) - 1;
+	tm->tm_mday = data[RTC_DATE] & 0x1f;
+	tm->tm_mon = (data[RTC_MONTH] & 0x0f) - 1;
+	tm->tm_year = (data[RTC_YEAR] & 0x7f) + 100;
+	tm->tm_yday = 0;
+	tm->tm_isdst = 0;
+}
+
+static int max8997_rtc_tm_to_data(struct rtc_time *tm, u8 *data)
+{
+	data[RTC_SEC] = tm->tm_sec;
+	data[RTC_MIN] = tm->tm_min;
+	data[RTC_HOUR] = tm->tm_hour;
+	data[RTC_WEEKDAY] = 1 << tm->tm_wday;
+	data[RTC_DATE] = tm->tm_mday;
+	data[RTC_MONTH] = tm->tm_mon + 1;
+	data[RTC_YEAR] = tm->tm_year > 100 ? (tm->tm_year - 100) : 0;
+
+	if (tm->tm_year < 100) {
+		pr_warn("RTC cannot handle the year %d.  Assume it's 2000.\n",
+			1900 + tm->tm_year);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static inline int max8997_rtc_set_update_reg(struct max8997_rtc_info *info)
+{
+	int ret;
+
+	ret = max8997_write_reg(info->rtc, MAX8997_RTC_UPDATE1,
+						RTC_UDR_MASK);
+	if (ret < 0)
+		dev_err(info->dev, "%s: fail to write update reg(%d)\n",
+				__func__, ret);
+	else {
+		/* Minimum 16ms delay required before RTC update.
+		 * Otherwise, we may read and update based on out-of-date
+		 * value */
+		msleep(20);
+	}
+
+	return ret;
+}
+
+static int max8997_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct max8997_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	int ret;
+
+	mutex_lock(&info->lock);
+	ret = max8997_bulk_read(info->rtc, MAX8997_RTC_SEC, RTC_NR_TIME, data);
+	mutex_unlock(&info->lock);
+
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to read time reg(%d)\n", __func__,
+				ret);
+		return ret;
+	}
+
+	max8997_rtc_data_to_tm(data, tm, info->rtc_24hr_mode);
+
+	return 0;
+}
+
+static int max8997_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct max8997_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	int ret;
+
+	ret = max8997_rtc_tm_to_data(tm, data);
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&info->lock);
+
+	ret = max8997_bulk_write(info->rtc, MAX8997_RTC_SEC, RTC_NR_TIME, data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to write time reg(%d)\n", __func__,
+				ret);
+		goto out;
+	}
+
+	ret = max8997_rtc_set_update_reg(info);
+out:
+	mutex_unlock(&info->lock);
+	return ret;
+}
+
+static int max8997_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct max8997_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	u8 val;
+	int i, ret;
+
+	mutex_lock(&info->lock);
+
+	ret = max8997_bulk_read(info->rtc, MAX8997_RTC_ALARM1_SEC, RTC_NR_TIME,
+			data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s:%d fail to read alarm reg(%d)\n",
+				__func__, __LINE__, ret);
+		goto out;
+	}
+
+	max8997_rtc_data_to_tm(data, &alrm->time, info->rtc_24hr_mode);
+
+	alrm->enabled = 0;
+	for (i = 0; i < RTC_NR_TIME; i++) {
+		if (data[i] & ALARM_ENABLE_MASK) {
+			alrm->enabled = 1;
+			break;
+		}
+	}
+
+	alrm->pending = 0;
+	ret = max8997_read_reg(info->max8997->i2c, MAX8997_REG_STATUS1, &val);
+	if (ret < 0) {
+		dev_err(info->dev, "%s:%d fail to read status1 reg(%d)\n",
+				__func__, __LINE__, ret);
+		goto out;
+	}
+
+	if (val & (1 << 4)) /* RTCA1 */
+		alrm->pending = 1;
+
+out:
+	mutex_unlock(&info->lock);
+	return ret;
+}
+
+static int max8997_rtc_stop_alarm(struct max8997_rtc_info *info)
+{
+	u8 data[RTC_NR_TIME];
+	int ret, i;
+
+	if (!mutex_is_locked(&info->lock))
+		dev_warn(info->dev, "%s: should have mutex locked\n", __func__);
+
+	ret = max8997_bulk_read(info->rtc, MAX8997_RTC_ALARM1_SEC, RTC_NR_TIME,
+				data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to read alarm reg(%d)\n",
+				__func__, ret);
+		goto out;
+	}
+
+	for (i = 0; i < RTC_NR_TIME; i++)
+		data[i] &= ~ALARM_ENABLE_MASK;
+
+	ret = max8997_bulk_write(info->rtc, MAX8997_RTC_ALARM1_SEC, RTC_NR_TIME,
+				 data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to write alarm reg(%d)\n",
+				__func__, ret);
+		goto out;
+	}
+
+	ret = max8997_rtc_set_update_reg(info);
+out:
+	return ret;
+}
+
+static int max8997_rtc_start_alarm(struct max8997_rtc_info *info)
+{
+	u8 data[RTC_NR_TIME];
+	int ret;
+
+	if (!mutex_is_locked(&info->lock))
+		dev_warn(info->dev, "%s: should have mutex locked\n", __func__);
+
+	ret = max8997_bulk_read(info->rtc, MAX8997_RTC_ALARM1_SEC, RTC_NR_TIME,
+				data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to read alarm reg(%d)\n",
+				__func__, ret);
+		goto out;
+	}
+
+	data[RTC_SEC] |= (1 << ALARM_ENABLE_SHIFT);
+	data[RTC_MIN] |= (1 << ALARM_ENABLE_SHIFT);
+	data[RTC_HOUR] |= (1 << ALARM_ENABLE_SHIFT);
+	data[RTC_WEEKDAY] &= ~ALARM_ENABLE_MASK;
+	if (data[RTC_MONTH] & 0xf)
+		data[RTC_MONTH] |= (1 << ALARM_ENABLE_SHIFT);
+	if (data[RTC_YEAR] & 0x7f)
+		data[RTC_YEAR] |= (1 << ALARM_ENABLE_SHIFT);
+	if (data[RTC_DATE] & 0x1f)
+		data[RTC_DATE] |= (1 << ALARM_ENABLE_SHIFT);
+
+	ret = max8997_bulk_write(info->rtc, MAX8997_RTC_ALARM1_SEC, RTC_NR_TIME,
+				 data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to write alarm reg(%d)\n",
+				__func__, ret);
+		goto out;
+	}
+
+	ret = max8997_rtc_set_update_reg(info);
+out:
+	return ret;
+}
+static int max8997_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct max8997_rtc_info *info = dev_get_drvdata(dev);
+	u8 data[RTC_NR_TIME];
+	int ret;
+
+	ret = max8997_rtc_tm_to_data(&alrm->time, data);
+	if (ret < 0)
+		return ret;
+
+	dev_info(info->dev, "%s: %d-%02d-%02d %02d:%02d:%02d\n", __func__,
+			data[RTC_YEAR] + 2000, data[RTC_MONTH], data[RTC_DATE],
+			data[RTC_HOUR], data[RTC_MIN], data[RTC_SEC]);
+
+	mutex_lock(&info->lock);
+
+	ret = max8997_rtc_stop_alarm(info);
+	if (ret < 0)
+		goto out;
+
+	ret = max8997_bulk_write(info->rtc, MAX8997_RTC_ALARM1_SEC, RTC_NR_TIME,
+				data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to write alarm reg(%d)\n",
+				__func__, ret);
+		goto out;
+	}
+
+	ret = max8997_rtc_set_update_reg(info);
+	if (ret < 0)
+		goto out;
+
+	if (alrm->enabled)
+		ret = max8997_rtc_start_alarm(info);
+out:
+	mutex_unlock(&info->lock);
+	return ret;
+}
+
+static int max8997_rtc_alarm_irq_enable(struct device *dev,
+					unsigned int enabled)
+{
+	struct max8997_rtc_info *info = dev_get_drvdata(dev);
+	int ret;
+
+	mutex_lock(&info->lock);
+	if (enabled)
+		ret = max8997_rtc_start_alarm(info);
+	else
+		ret = max8997_rtc_stop_alarm(info);
+	mutex_unlock(&info->lock);
+
+	return ret;
+}
+
+static irqreturn_t max8997_rtc_alarm_irq(int irq, void *data)
+{
+	struct max8997_rtc_info *info = data;
+
+	dev_info(info->dev, "%s:irq(%d)\n", __func__, irq);
+
+	rtc_update_irq(info->rtc_dev, 1, RTC_IRQF | RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops max8997_rtc_ops = {
+	.read_time = max8997_rtc_read_time,
+	.set_time = max8997_rtc_set_time,
+	.read_alarm = max8997_rtc_read_alarm,
+	.set_alarm = max8997_rtc_set_alarm,
+	.alarm_irq_enable = max8997_rtc_alarm_irq_enable,
+};
+
+static void max8997_rtc_enable_wtsr(struct max8997_rtc_info *info, bool enable)
+{
+	int ret;
+	u8 val, mask;
+
+	if (!wtsr_en)
+		return;
+
+	if (enable)
+		val = (1 << WTSR_EN_SHIFT) | (3 << WTSRT_SHIFT);
+	else
+		val = 0;
+
+	mask = WTSR_EN_MASK | WTSRT_MASK;
+
+	dev_info(info->dev, "%s: %s WTSR\n", __func__,
+			enable ? "enable" : "disable");
+
+	ret = max8997_update_reg(info->rtc, MAX8997_RTC_WTSR_SMPL, val, mask);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to update WTSR reg(%d)\n",
+				__func__, ret);
+		return;
+	}
+
+	max8997_rtc_set_update_reg(info);
+}
+
+static void max8997_rtc_enable_smpl(struct max8997_rtc_info *info, bool enable)
+{
+	int ret;
+	u8 val, mask;
+
+	if (!smpl_en)
+		return;
+
+	if (enable)
+		val = (1 << SMPL_EN_SHIFT) | (0 << SMPLT_SHIFT);
+	else
+		val = 0;
+
+	mask = SMPL_EN_MASK | SMPLT_MASK;
+
+	dev_info(info->dev, "%s: %s SMPL\n", __func__,
+			enable ? "enable" : "disable");
+
+	ret = max8997_update_reg(info->rtc, MAX8997_RTC_WTSR_SMPL, val, mask);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to update SMPL reg(%d)\n",
+				__func__, ret);
+		return;
+	}
+
+	max8997_rtc_set_update_reg(info);
+
+	val = 0;
+	max8997_read_reg(info->rtc, MAX8997_RTC_WTSR_SMPL, &val);
+	pr_info("WTSR_SMPL(0x%02x)\n", val);
+}
+
+static int max8997_rtc_init_reg(struct max8997_rtc_info *info)
+{
+	u8 data[2];
+	int ret;
+
+	/* Set RTC control register : Binary mode, 24hour mdoe */
+	data[0] = (1 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
+	data[1] = (0 << BCD_EN_SHIFT) | (1 << MODEL24_SHIFT);
+
+	info->rtc_24hr_mode = 1;
+
+	ret = max8997_bulk_write(info->rtc, MAX8997_RTC_CTRLMASK, 2, data);
+	if (ret < 0) {
+		dev_err(info->dev, "%s: fail to write controlm reg(%d)\n",
+				__func__, ret);
+		return ret;
+	}
+
+	ret = max8997_rtc_set_update_reg(info);
+	return ret;
+}
+
+static int max8997_rtc_probe(struct platform_device *pdev)
+{
+	struct max8997_dev *max8997 = dev_get_drvdata(pdev->dev.parent);
+	struct max8997_rtc_info *info;
+	int ret, virq;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(struct max8997_rtc_info),
+			GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	mutex_init(&info->lock);
+	info->dev = &pdev->dev;
+	info->max8997 = max8997;
+	info->rtc = max8997->rtc;
+
+	platform_set_drvdata(pdev, info);
+
+	ret = max8997_rtc_init_reg(info);
+
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to initialize RTC reg:%d\n", ret);
+		return ret;
+	}
+
+	max8997_rtc_enable_wtsr(info, true);
+	max8997_rtc_enable_smpl(info, true);
+
+	device_init_wakeup(&pdev->dev, true);
+
+	info->rtc_dev = devm_rtc_device_register(&pdev->dev, "max8997-rtc",
+					&max8997_rtc_ops, THIS_MODULE);
+
+	if (IS_ERR(info->rtc_dev)) {
+		ret = PTR_ERR(info->rtc_dev);
+		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
+		return ret;
+	}
+
+	virq = irq_create_mapping(max8997->irq_domain, MAX8997_PMICIRQ_RTCA1);
+	if (!virq) {
+		dev_err(&pdev->dev, "Failed to create mapping alarm IRQ\n");
+		ret = -ENXIO;
+		goto err_out;
+	}
+	info->virq = virq;
+
+	ret = devm_request_threaded_irq(&pdev->dev, virq, NULL,
+				max8997_rtc_alarm_irq, 0,
+				"rtc-alarm0", info);
+	if (ret < 0)
+		dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d\n",
+			info->virq, ret);
+
+err_out:
+	return ret;
+}
+
+static void max8997_rtc_shutdown(struct platform_device *pdev)
+{
+	struct max8997_rtc_info *info = platform_get_drvdata(pdev);
+
+	max8997_rtc_enable_wtsr(info, false);
+	max8997_rtc_enable_smpl(info, false);
+}
+
+static const struct platform_device_id rtc_id[] = {
+	{ .name = "max8997-rtc" },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, rtc_id);
+
+static struct platform_driver max8997_rtc_driver = {
+	.driver		= {
+		.name	= "max8997-rtc",
+	},
+	.probe		= max8997_rtc_probe,
+	.shutdown	= max8997_rtc_shutdown,
+	.id_table	= rtc_id,
+};
+
+module_platform_driver(max8997_rtc_driver);
+
+MODULE_DESCRIPTION("Maxim MAX8997 RTC driver");
+MODULE_AUTHOR("<ms925.kim@samsung.com>");
+MODULE_LICENSE("GPL");