From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena 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 Reviewed-by: Andrea Righi --- drivers/soc/tegra/flowctrl.c | 226 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 226 insertions(+) create mode 100644 drivers/soc/tegra/flowctrl.c (limited to 'drivers/soc/tegra/flowctrl.c') diff --git a/drivers/soc/tegra/flowctrl.c b/drivers/soc/tegra/flowctrl.c new file mode 100644 index 000000000..221202db3 --- /dev/null +++ b/drivers/soc/tegra/flowctrl.c @@ -0,0 +1,226 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * drivers/soc/tegra/flowctrl.c + * + * Functions and macros to control the flowcontroller + * + * Copyright (c) 2010-2012, NVIDIA Corporation. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +static u8 flowctrl_offset_halt_cpu[] = { + FLOW_CTRL_HALT_CPU0_EVENTS, + FLOW_CTRL_HALT_CPU1_EVENTS, + FLOW_CTRL_HALT_CPU1_EVENTS + 8, + FLOW_CTRL_HALT_CPU1_EVENTS + 16, +}; + +static u8 flowctrl_offset_cpu_csr[] = { + FLOW_CTRL_CPU0_CSR, + FLOW_CTRL_CPU1_CSR, + FLOW_CTRL_CPU1_CSR + 8, + FLOW_CTRL_CPU1_CSR + 16, +}; + +static void __iomem *tegra_flowctrl_base; + +static void flowctrl_update(u8 offset, u32 value) +{ + if (WARN_ONCE(IS_ERR_OR_NULL(tegra_flowctrl_base), + "Tegra flowctrl not initialised!\n")) + return; + + writel(value, tegra_flowctrl_base + offset); + + /* ensure the update has reached the flow controller */ + wmb(); + readl_relaxed(tegra_flowctrl_base + offset); +} + +u32 flowctrl_read_cpu_csr(unsigned int cpuid) +{ + u8 offset = flowctrl_offset_cpu_csr[cpuid]; + + if (WARN_ONCE(IS_ERR_OR_NULL(tegra_flowctrl_base), + "Tegra flowctrl not initialised!\n")) + return 0; + + return readl(tegra_flowctrl_base + offset); +} + +void flowctrl_write_cpu_csr(unsigned int cpuid, u32 value) +{ + return flowctrl_update(flowctrl_offset_cpu_csr[cpuid], value); +} + +void flowctrl_write_cpu_halt(unsigned int cpuid, u32 value) +{ + return flowctrl_update(flowctrl_offset_halt_cpu[cpuid], value); +} + +void flowctrl_cpu_suspend_enter(unsigned int cpuid) +{ + unsigned int reg; + int i; + + reg = flowctrl_read_cpu_csr(cpuid); + switch (tegra_get_chip_id()) { + case TEGRA20: + /* clear wfe bitmap */ + reg &= ~TEGRA20_FLOW_CTRL_CSR_WFE_BITMAP; + /* clear wfi bitmap */ + reg &= ~TEGRA20_FLOW_CTRL_CSR_WFI_BITMAP; + /* pwr gating on wfe */ + reg |= TEGRA20_FLOW_CTRL_CSR_WFE_CPU0 << cpuid; + break; + case TEGRA30: + case TEGRA114: + case TEGRA124: + /* clear wfe bitmap */ + reg &= ~TEGRA30_FLOW_CTRL_CSR_WFE_BITMAP; + /* clear wfi bitmap */ + reg &= ~TEGRA30_FLOW_CTRL_CSR_WFI_BITMAP; + + if (tegra_get_chip_id() == TEGRA30) { + /* + * The wfi doesn't work well on Tegra30 because + * CPU hangs under some odd circumstances after + * power-gating (like memory running off PLLP), + * hence use wfe that is working perfectly fine. + * Note that Tegra30 TRM doc clearly stands that + * wfi should be used for the "Cluster Switching", + * while wfe for the power-gating, just like it + * is done on Tegra20. + */ + reg |= TEGRA20_FLOW_CTRL_CSR_WFE_CPU0 << cpuid; + } else { + /* pwr gating on wfi */ + reg |= TEGRA30_FLOW_CTRL_CSR_WFI_CPU0 << cpuid; + } + break; + } + reg |= FLOW_CTRL_CSR_INTR_FLAG; /* clear intr flag */ + reg |= FLOW_CTRL_CSR_EVENT_FLAG; /* clear event flag */ + reg |= FLOW_CTRL_CSR_ENABLE; /* pwr gating */ + flowctrl_write_cpu_csr(cpuid, reg); + + for (i = 0; i < num_possible_cpus(); i++) { + if (i == cpuid) + continue; + reg = flowctrl_read_cpu_csr(i); + reg |= FLOW_CTRL_CSR_EVENT_FLAG; + reg |= FLOW_CTRL_CSR_INTR_FLAG; + flowctrl_write_cpu_csr(i, reg); + } +} + +void flowctrl_cpu_suspend_exit(unsigned int cpuid) +{ + unsigned int reg; + + /* Disable powergating via flow controller for CPU0 */ + reg = flowctrl_read_cpu_csr(cpuid); + switch (tegra_get_chip_id()) { + case TEGRA20: + /* clear wfe bitmap */ + reg &= ~TEGRA20_FLOW_CTRL_CSR_WFE_BITMAP; + /* clear wfi bitmap */ + reg &= ~TEGRA20_FLOW_CTRL_CSR_WFI_BITMAP; + break; + case TEGRA30: + case TEGRA114: + case TEGRA124: + /* clear wfe bitmap */ + reg &= ~TEGRA30_FLOW_CTRL_CSR_WFE_BITMAP; + /* clear wfi bitmap */ + reg &= ~TEGRA30_FLOW_CTRL_CSR_WFI_BITMAP; + break; + } + reg &= ~FLOW_CTRL_CSR_ENABLE; /* clear enable */ + reg |= FLOW_CTRL_CSR_INTR_FLAG; /* clear intr */ + reg |= FLOW_CTRL_CSR_EVENT_FLAG; /* clear event */ + flowctrl_write_cpu_csr(cpuid, reg); +} + +static int tegra_flowctrl_probe(struct platform_device *pdev) +{ + void __iomem *base = tegra_flowctrl_base; + + tegra_flowctrl_base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); + if (IS_ERR(tegra_flowctrl_base)) + return PTR_ERR(tegra_flowctrl_base); + + iounmap(base); + + return 0; +} + +static const struct of_device_id tegra_flowctrl_match[] = { + { .compatible = "nvidia,tegra210-flowctrl" }, + { .compatible = "nvidia,tegra124-flowctrl" }, + { .compatible = "nvidia,tegra114-flowctrl" }, + { .compatible = "nvidia,tegra30-flowctrl" }, + { .compatible = "nvidia,tegra20-flowctrl" }, + { } +}; + +static struct platform_driver tegra_flowctrl_driver = { + .driver = { + .name = "tegra-flowctrl", + .suppress_bind_attrs = true, + .of_match_table = tegra_flowctrl_match, + }, + .probe = tegra_flowctrl_probe, +}; +builtin_platform_driver(tegra_flowctrl_driver); + +static int __init tegra_flowctrl_init(void) +{ + struct resource res; + struct device_node *np; + + if (!soc_is_tegra()) + return 0; + + np = of_find_matching_node(NULL, tegra_flowctrl_match); + if (np) { + if (of_address_to_resource(np, 0, &res) < 0) { + pr_err("failed to get flowctrl register\n"); + return -ENXIO; + } + of_node_put(np); + } else if (IS_ENABLED(CONFIG_ARM)) { + /* + * Hardcoded fallback for 32-bit Tegra + * devices if device tree node is missing. + */ + res.start = 0x60007000; + res.end = 0x60007fff; + res.flags = IORESOURCE_MEM; + } else { + /* + * At this point we're running on a Tegra, + * that doesn't support the flow controller + * (eg. Tegra186), so just return. + */ + return 0; + } + + tegra_flowctrl_base = ioremap(res.start, resource_size(&res)); + if (!tegra_flowctrl_base) + return -ENXIO; + + return 0; +} +early_initcall(tegra_flowctrl_init); -- cgit v1.3.1