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>

3 files changed, 313 insertions, 0 deletions

diff --git a/drivers/phy/sunplus/Kconfig b/drivers/phy/sunplus/Kconfig
new file mode 100644
index 000000000..3bd3cfb53
--- /dev/null
+++ b/drivers/phy/sunplus/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+config PHY_SUNPLUS_USB
+	tristate "Sunplus SP7021 USB 2.0 PHY driver"
+	depends on OF && (SOC_SP7021 || COMPILE_TEST)
+	select GENERIC_PHY
+	help
+	  Enable this to support the USB 2.0 PHY on Sunplus SP7021
+	  SoC. The USB 2.0 PHY controller supports battery charger
+	  and synchronous signals, various power down modes including
+	  operating, partial and suspend modes, and high-speed,
+	  full-speed and low-speed data transfer.
diff --git a/drivers/phy/sunplus/Makefile b/drivers/phy/sunplus/Makefile
new file mode 100644
index 000000000..71754d5cb
--- /dev/null
+++ b/drivers/phy/sunplus/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_PHY_SUNPLUS_USB)	+= phy-sunplus-usb2.o
diff --git a/drivers/phy/sunplus/phy-sunplus-usb2.c b/drivers/phy/sunplus/phy-sunplus-usb2.c
new file mode 100644
index 000000000..637a5fbae
--- /dev/null
+++ b/drivers/phy/sunplus/phy-sunplus-usb2.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Sunplus SP7021 USB 2.0 phy driver
+ *
+ * Copyright (C) 2022 Sunplus Technology Inc., All rights reserved.
+ *
+ * Note 1 : non-posted write command for the registers accesses of
+ * Sunplus SP7021.
+ *
+ */
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/of.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+
+#define HIGH_MASK_BITS				GENMASK(31, 16)
+#define LOW_MASK_BITS				GENMASK(15, 0)
+#define OTP_DISC_LEVEL_DEFAULT			0xd
+
+/* GROUP UPHY */
+#define CONFIG1					0x4
+#define J_HS_TX_PWRSAV				BIT(5)
+#define CONFIG3					0xc
+#define J_FORCE_DISC_ON				BIT(5)
+#define J_DEBUG_CTRL_ADDR_MACRO			BIT(0)
+#define CONFIG7					0x1c
+#define J_DISC					0X1f
+#define CONFIG9					0x24
+#define J_ECO_PATH				BIT(6)
+#define CONFIG16				0x40
+#define J_TBCWAIT_MASK				GENMASK(6, 5)
+#define J_TBCWAIT_1P1_MS			FIELD_PREP(J_TBCWAIT_MASK, 0)
+#define J_TVDM_SRC_DIS_MASK			GENMASK(4, 3)
+#define J_TVDM_SRC_DIS_8P2_MS			FIELD_PREP(J_TVDM_SRC_DIS_MASK, 3)
+#define J_TVDM_SRC_EN_MASK			GENMASK(2, 1)
+#define J_TVDM_SRC_EN_1P6_MS			FIELD_PREP(J_TVDM_SRC_EN_MASK, 0)
+#define J_BC_EN					BIT(0)
+#define CONFIG17				0x44
+#define IBG_TRIM0_MASK				GENMASK(7, 5)
+#define IBG_TRIM0_SSLVHT			FIELD_PREP(IBG_TRIM0_MASK, 4)
+#define J_VDATREE_TRIM_MASK			GENMASK(4, 1)
+#define J_VDATREE_TRIM_DEFAULT			FIELD_PREP(J_VDATREE_TRIM_MASK, 9)
+#define CONFIG23				0x5c
+#define PROB_MASK				GENMASK(5, 3)
+#define PROB					FIELD_PREP(PROB_MASK, 7)
+
+/* GROUP MOON4 */
+#define UPHY_CONTROL0				0x0
+#define UPHY_CONTROL1				0x4
+#define UPHY_CONTROL2				0x8
+#define MO1_UPHY_RX_CLK_SEL			BIT(6)
+#define MASK_MO1_UPHY_RX_CLK_SEL		BIT(6 + 16)
+#define UPHY_CONTROL3				0xc
+#define MO1_UPHY_PLL_POWER_OFF_SEL		BIT(7)
+#define MASK_MO1_UPHY_PLL_POWER_OFF_SEL		BIT(7 + 16)
+#define MO1_UPHY_PLL_POWER_OFF			BIT(3)
+#define MASK_UPHY_PLL_POWER_OFF			BIT(3 + 16)
+
+struct sp_usbphy {
+	struct device *dev;
+	struct resource *phy_res_mem;
+	struct resource *moon4_res_mem;
+	struct reset_control *rstc;
+	struct clk *phy_clk;
+	void __iomem *phy_regs;
+	void __iomem *moon4_regs;
+	u32 disc_vol_addr_off;
+};
+
+static int update_disc_vol(struct sp_usbphy *usbphy)
+{
+	struct nvmem_cell *cell;
+	char *disc_name = "disc_vol";
+	ssize_t otp_l = 0;
+	char *otp_v;
+	u32 val, set;
+
+	cell = nvmem_cell_get(usbphy->dev, disc_name);
+	if (IS_ERR_OR_NULL(cell)) {
+		if (PTR_ERR(cell) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+	}
+
+	otp_v = nvmem_cell_read(cell, &otp_l);
+	nvmem_cell_put(cell);
+
+	if (!IS_ERR(otp_v)) {
+		set = *(otp_v + 1);
+		set = (set << (sizeof(char) * 8)) | *otp_v;
+		set = (set >> usbphy->disc_vol_addr_off) & J_DISC;
+	}
+
+	if (IS_ERR(otp_v) || set == 0)
+		set = OTP_DISC_LEVEL_DEFAULT;
+
+	val = readl(usbphy->phy_regs + CONFIG7);
+	val = (val & ~J_DISC) | set;
+	writel(val, usbphy->phy_regs + CONFIG7);
+
+	return 0;
+}
+
+static int sp_uphy_init(struct phy *phy)
+{
+	struct sp_usbphy *usbphy = phy_get_drvdata(phy);
+	u32 val;
+	int ret;
+
+	ret = clk_prepare_enable(usbphy->phy_clk);
+	if (ret)
+		goto err_clk;
+
+	ret = reset_control_deassert(usbphy->rstc);
+	if (ret)
+		goto err_reset;
+
+	/* Default value modification */
+	writel(HIGH_MASK_BITS | 0x4002, usbphy->moon4_regs + UPHY_CONTROL0);
+	writel(HIGH_MASK_BITS | 0x8747, usbphy->moon4_regs + UPHY_CONTROL1);
+
+	/* disconnect voltage */
+	ret = update_disc_vol(usbphy);
+	if (ret < 0)
+		return ret;
+
+	/* board uphy 0 internal register modification for tid certification */
+	val = readl(usbphy->phy_regs + CONFIG9);
+	val &= ~(J_ECO_PATH);
+	writel(val, usbphy->phy_regs + CONFIG9);
+
+	val = readl(usbphy->phy_regs + CONFIG1);
+	val &= ~(J_HS_TX_PWRSAV);
+	writel(val, usbphy->phy_regs + CONFIG1);
+
+	val = readl(usbphy->phy_regs + CONFIG23);
+	val = (val & ~PROB) | PROB;
+	writel(val, usbphy->phy_regs + CONFIG23);
+
+	/* port 0 uphy clk fix */
+	writel(MASK_MO1_UPHY_RX_CLK_SEL | MO1_UPHY_RX_CLK_SEL,
+	       usbphy->moon4_regs + UPHY_CONTROL2);
+
+	/* battery charger */
+	writel(J_TBCWAIT_1P1_MS | J_TVDM_SRC_DIS_8P2_MS | J_TVDM_SRC_EN_1P6_MS | J_BC_EN,
+	       usbphy->phy_regs + CONFIG16);
+	writel(IBG_TRIM0_SSLVHT | J_VDATREE_TRIM_DEFAULT, usbphy->phy_regs + CONFIG17);
+
+	/* chirp mode */
+	writel(J_FORCE_DISC_ON | J_DEBUG_CTRL_ADDR_MACRO, usbphy->phy_regs + CONFIG3);
+
+	return 0;
+
+err_reset:
+	reset_control_assert(usbphy->rstc);
+err_clk:
+	clk_disable_unprepare(usbphy->phy_clk);
+
+	return ret;
+}
+
+static int sp_uphy_power_on(struct phy *phy)
+{
+	struct sp_usbphy *usbphy = phy_get_drvdata(phy);
+	u32 pll_pwr_on, pll_pwr_off;
+
+	/* PLL power off/on twice */
+	pll_pwr_off = (readl(usbphy->moon4_regs + UPHY_CONTROL3) & ~LOW_MASK_BITS)
+			| MO1_UPHY_PLL_POWER_OFF_SEL | MO1_UPHY_PLL_POWER_OFF;
+	pll_pwr_on = (readl(usbphy->moon4_regs + UPHY_CONTROL3) & ~LOW_MASK_BITS)
+			| MO1_UPHY_PLL_POWER_OFF_SEL;
+
+	writel(MASK_MO1_UPHY_PLL_POWER_OFF_SEL | MASK_UPHY_PLL_POWER_OFF | pll_pwr_off,
+	       usbphy->moon4_regs + UPHY_CONTROL3);
+	mdelay(1);
+	writel(MASK_MO1_UPHY_PLL_POWER_OFF_SEL | MASK_UPHY_PLL_POWER_OFF | pll_pwr_on,
+	       usbphy->moon4_regs + UPHY_CONTROL3);
+	mdelay(1);
+	writel(MASK_MO1_UPHY_PLL_POWER_OFF_SEL | MASK_UPHY_PLL_POWER_OFF | pll_pwr_off,
+	       usbphy->moon4_regs + UPHY_CONTROL3);
+	mdelay(1);
+	writel(MASK_MO1_UPHY_PLL_POWER_OFF_SEL | MASK_UPHY_PLL_POWER_OFF | pll_pwr_on,
+	       usbphy->moon4_regs + UPHY_CONTROL3);
+	mdelay(1);
+	writel(MASK_MO1_UPHY_PLL_POWER_OFF_SEL | MASK_UPHY_PLL_POWER_OFF | 0x0,
+	       usbphy->moon4_regs + UPHY_CONTROL3);
+
+	return 0;
+}
+
+static int sp_uphy_power_off(struct phy *phy)
+{
+	struct sp_usbphy *usbphy = phy_get_drvdata(phy);
+	u32 pll_pwr_off;
+
+	pll_pwr_off = (readl(usbphy->moon4_regs + UPHY_CONTROL3) & ~LOW_MASK_BITS)
+			| MO1_UPHY_PLL_POWER_OFF_SEL | MO1_UPHY_PLL_POWER_OFF;
+
+	writel(MASK_MO1_UPHY_PLL_POWER_OFF_SEL | MASK_UPHY_PLL_POWER_OFF | pll_pwr_off,
+	       usbphy->moon4_regs + UPHY_CONTROL3);
+	mdelay(1);
+	writel(MASK_MO1_UPHY_PLL_POWER_OFF_SEL | MASK_UPHY_PLL_POWER_OFF | 0x0,
+	       usbphy->moon4_regs + UPHY_CONTROL3);
+
+	return 0;
+}
+
+static int sp_uphy_exit(struct phy *phy)
+{
+	struct sp_usbphy *usbphy = phy_get_drvdata(phy);
+
+	reset_control_assert(usbphy->rstc);
+	clk_disable_unprepare(usbphy->phy_clk);
+
+	return 0;
+}
+
+static const struct phy_ops sp_uphy_ops = {
+	.init		= sp_uphy_init,
+	.power_on	= sp_uphy_power_on,
+	.power_off	= sp_uphy_power_off,
+	.exit		= sp_uphy_exit,
+};
+
+static const struct of_device_id sp_uphy_dt_ids[] = {
+	{.compatible = "sunplus,sp7021-usb2-phy", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sp_uphy_dt_ids);
+
+static int sp_usb_phy_probe(struct platform_device *pdev)
+{
+	struct sp_usbphy *usbphy;
+	struct phy_provider *phy_provider;
+	struct phy *phy;
+	int ret;
+
+	usbphy = devm_kzalloc(&pdev->dev, sizeof(*usbphy), GFP_KERNEL);
+	if (!usbphy)
+		return -ENOMEM;
+
+	usbphy->dev = &pdev->dev;
+
+	usbphy->phy_res_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM, "phy");
+	usbphy->phy_regs = devm_ioremap_resource(&pdev->dev, usbphy->phy_res_mem);
+	if (IS_ERR(usbphy->phy_regs))
+		return PTR_ERR(usbphy->phy_regs);
+
+	usbphy->moon4_res_mem = platform_get_resource_byname(pdev, IORESOURCE_MEM, "moon4");
+	if (!usbphy->moon4_res_mem)
+		return -EINVAL;
+
+	usbphy->moon4_regs = devm_ioremap(&pdev->dev, usbphy->moon4_res_mem->start,
+					  resource_size(usbphy->moon4_res_mem));
+	if (!usbphy->moon4_regs)
+		return -ENOMEM;
+
+	usbphy->phy_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(usbphy->phy_clk))
+		return PTR_ERR(usbphy->phy_clk);
+
+	usbphy->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(usbphy->rstc))
+		return PTR_ERR(usbphy->rstc);
+
+	of_property_read_u32(pdev->dev.of_node, "sunplus,disc-vol-addr-off",
+			     &usbphy->disc_vol_addr_off);
+
+	phy = devm_phy_create(&pdev->dev, NULL, &sp_uphy_ops);
+	if (IS_ERR(phy)) {
+		ret = PTR_ERR(phy);
+		return ret;
+	}
+
+	phy_set_drvdata(phy, usbphy);
+	phy_provider = devm_of_phy_provider_register(&pdev->dev, of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static struct platform_driver sunplus_usb_phy_driver = {
+	.probe		= sp_usb_phy_probe,
+	.driver		= {
+		.name	= "sunplus-usb2-phy",
+		.of_match_table = sp_uphy_dt_ids,
+	},
+};
+module_platform_driver(sunplus_usb_phy_driver);
+
+MODULE_AUTHOR("Vincent Shih <vincent.shih@sunplus.com>");
+MODULE_DESCRIPTION("Sunplus USB 2.0 phy driver");
+MODULE_LICENSE("GPL");