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/clocksource/timer-msc313e.c | 253 ++++++++++++++++++++++++++++++++++++ 1 file changed, 253 insertions(+) create mode 100644 drivers/clocksource/timer-msc313e.c (limited to 'drivers/clocksource/timer-msc313e.c') diff --git a/drivers/clocksource/timer-msc313e.c b/drivers/clocksource/timer-msc313e.c new file mode 100644 index 000000000..e4b9e3f16 --- /dev/null +++ b/drivers/clocksource/timer-msc313e.c @@ -0,0 +1,253 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * MStar timer driver + * + * Copyright (C) 2021 Daniel Palmer + * Copyright (C) 2021 Romain Perier + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifdef CONFIG_ARM +#include +#endif + +#include "timer-of.h" + +#define TIMER_NAME "msc313e_timer" + +#define MSC313E_REG_CTRL 0x00 +#define MSC313E_REG_CTRL_TIMER_EN BIT(0) +#define MSC313E_REG_CTRL_TIMER_TRIG BIT(1) +#define MSC313E_REG_CTRL_TIMER_INT_EN BIT(8) +#define MSC313E_REG_TIMER_MAX_LOW 0x08 +#define MSC313E_REG_TIMER_MAX_HIGH 0x0c +#define MSC313E_REG_COUNTER_LOW 0x10 +#define MSC313E_REG_COUNTER_HIGH 0x14 +#define MSC313E_REG_TIMER_DIVIDE 0x18 + +#define MSC313E_CLK_DIVIDER 9 +#define TIMER_SYNC_TICKS 3 + +#ifdef CONFIG_ARM +struct msc313e_delay { + void __iomem *base; + struct delay_timer delay; +}; +static struct msc313e_delay msc313e_delay; +#endif + +static void __iomem *msc313e_clksrc; + +static void msc313e_timer_stop(void __iomem *base) +{ + writew(0, base + MSC313E_REG_CTRL); +} + +static void msc313e_timer_start(void __iomem *base, bool periodic) +{ + u16 reg; + + reg = readw(base + MSC313E_REG_CTRL); + if (periodic) + reg |= MSC313E_REG_CTRL_TIMER_EN; + else + reg |= MSC313E_REG_CTRL_TIMER_TRIG; + writew(reg | MSC313E_REG_CTRL_TIMER_INT_EN, base + MSC313E_REG_CTRL); +} + +static void msc313e_timer_setup(void __iomem *base, unsigned long delay) +{ + unsigned long flags; + + local_irq_save(flags); + writew(delay >> 16, base + MSC313E_REG_TIMER_MAX_HIGH); + writew(delay & 0xffff, base + MSC313E_REG_TIMER_MAX_LOW); + local_irq_restore(flags); +} + +static unsigned long msc313e_timer_current_value(void __iomem *base) +{ + unsigned long flags; + u16 l, h; + + local_irq_save(flags); + l = readw(base + MSC313E_REG_COUNTER_LOW); + h = readw(base + MSC313E_REG_COUNTER_HIGH); + local_irq_restore(flags); + + return (((u32)h) << 16 | l); +} + +static int msc313e_timer_clkevt_shutdown(struct clock_event_device *evt) +{ + struct timer_of *timer = to_timer_of(evt); + + msc313e_timer_stop(timer_of_base(timer)); + + return 0; +} + +static int msc313e_timer_clkevt_set_oneshot(struct clock_event_device *evt) +{ + struct timer_of *timer = to_timer_of(evt); + + msc313e_timer_stop(timer_of_base(timer)); + msc313e_timer_start(timer_of_base(timer), false); + + return 0; +} + +static int msc313e_timer_clkevt_set_periodic(struct clock_event_device *evt) +{ + struct timer_of *timer = to_timer_of(evt); + + msc313e_timer_stop(timer_of_base(timer)); + msc313e_timer_setup(timer_of_base(timer), timer_of_period(timer)); + msc313e_timer_start(timer_of_base(timer), true); + + return 0; +} + +static int msc313e_timer_clkevt_next_event(unsigned long evt, struct clock_event_device *clkevt) +{ + struct timer_of *timer = to_timer_of(clkevt); + + msc313e_timer_stop(timer_of_base(timer)); + msc313e_timer_setup(timer_of_base(timer), evt); + msc313e_timer_start(timer_of_base(timer), false); + + return 0; +} + +static irqreturn_t msc313e_timer_clkevt_irq(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static u64 msc313e_timer_clksrc_read(struct clocksource *cs) +{ + return msc313e_timer_current_value(msc313e_clksrc) & cs->mask; +} + +#ifdef CONFIG_ARM +static unsigned long msc313e_read_delay_timer_read(void) +{ + return msc313e_timer_current_value(msc313e_delay.base); +} +#endif + +static u64 msc313e_timer_sched_clock_read(void) +{ + return msc313e_timer_current_value(msc313e_clksrc); +} + +static struct clock_event_device msc313e_clkevt = { + .name = TIMER_NAME, + .rating = 300, + .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, + .set_state_shutdown = msc313e_timer_clkevt_shutdown, + .set_state_periodic = msc313e_timer_clkevt_set_periodic, + .set_state_oneshot = msc313e_timer_clkevt_set_oneshot, + .tick_resume = msc313e_timer_clkevt_shutdown, + .set_next_event = msc313e_timer_clkevt_next_event, +}; + +static int __init msc313e_clkevt_init(struct device_node *np) +{ + int ret; + struct timer_of *to; + + to = kzalloc_obj(*to); + if (!to) + return -ENOMEM; + + to->flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE; + to->of_irq.handler = msc313e_timer_clkevt_irq; + ret = timer_of_init(np, to); + if (ret) + return ret; + + if (of_device_is_compatible(np, "sstar,ssd20xd-timer")) { + to->of_clk.rate = clk_get_rate(to->of_clk.clk) / MSC313E_CLK_DIVIDER; + to->of_clk.period = DIV_ROUND_UP(to->of_clk.rate, HZ); + writew(MSC313E_CLK_DIVIDER - 1, timer_of_base(to) + MSC313E_REG_TIMER_DIVIDE); + } + + msc313e_clkevt.cpumask = cpu_possible_mask; + msc313e_clkevt.irq = to->of_irq.irq; + to->clkevt = msc313e_clkevt; + + clockevents_config_and_register(&to->clkevt, timer_of_rate(to), + TIMER_SYNC_TICKS, 0xffffffff); + return 0; +} + +static int __init msc313e_clksrc_init(struct device_node *np) +{ + struct timer_of to = { 0 }; + int ret; + u16 reg; + + to.flags = TIMER_OF_BASE | TIMER_OF_CLOCK; + ret = timer_of_init(np, &to); + if (ret) + return ret; + + msc313e_clksrc = timer_of_base(&to); + reg = readw(msc313e_clksrc + MSC313E_REG_CTRL); + reg |= MSC313E_REG_CTRL_TIMER_EN; + writew(reg, msc313e_clksrc + MSC313E_REG_CTRL); + +#ifdef CONFIG_ARM + msc313e_delay.base = timer_of_base(&to); + msc313e_delay.delay.read_current_timer = msc313e_read_delay_timer_read; + msc313e_delay.delay.freq = timer_of_rate(&to); + + register_current_timer_delay(&msc313e_delay.delay); +#endif + + sched_clock_register(msc313e_timer_sched_clock_read, 32, timer_of_rate(&to)); + return clocksource_mmio_init(timer_of_base(&to), TIMER_NAME, timer_of_rate(&to), 300, 32, + msc313e_timer_clksrc_read); +} + +static int __init msc313e_timer_init(struct device_node *np) +{ + int ret = 0; + static int num_called; + + switch (num_called) { + case 0: + ret = msc313e_clksrc_init(np); + if (ret) + return ret; + break; + + default: + ret = msc313e_clkevt_init(np); + if (ret) + return ret; + break; + } + + num_called++; + + return 0; +} + +TIMER_OF_DECLARE(msc313, "mstar,msc313e-timer", msc313e_timer_init); +TIMER_OF_DECLARE(ssd20xd, "sstar,ssd20xd-timer", msc313e_timer_init); -- cgit v1.3.1