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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
| commit | 4352b8aee98005853aa63f57d6377282de17a33f (patch) | |
| tree | 27614d7a9ef05c32d089004e104364ce42324837 /drivers/clocksource/timer-atmel-pit.c | |
| download | linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip | |
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni:
"A new driver this cycle, for the AMD AXI I3C controller.
There are also new features such as IBI wakeup support, SETAASA device
discovery and ACPI support for the the DAA methods, meaning we can now
communicate with the SPD devices on DDR5 modules.
New driver:
- AMD AXI I3C master controller
Subsystem:
- I3C Common Command Code (CCC) handling improvements, especially
around GET CCCs
- SETAASA device discovery support
- ACPI support for all existing DAA methods like SETDASA, SETNEWDA as
well as I2C devices on I3C bus
- IBI-based wakeup support
Drivers:
- dw: SETAASA support
- mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C
controller support, PIO queue management support for HCI v1.2
- renesas: improve suspend to RAM support, add runtime PM support"
* tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits)
i3c: dw: reduce do_daa time if there's no client
i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller
i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2
i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode
i3c: dw: rename "pclk" to "apb" to match dt-binding
i3c: dw: make struct dw_i3c_cmd smaller
i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding
i3c: renesas: Don't register devices when ENTDAA times out
i3c: master: dw-i3c-master: fix OD timing for first broadcast
i3c: mipi-i3c-hci: Advertise IBI wakeup capability
i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()
i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI
i3c: master: Reject IBI requests from non-IBI-capable devices
i3c: master: Add helper to query bus wakeup requirements
i3c: master: Report wakeup events for IBIs
i3c: master: Support IBI-based wakeup capability
i3c: master: Fix potential UAF in i3c_device_match()
i3c: master: Fix potential UAF in i3c_device_uevent()
i3c: Make dev->desc locking assumptions explicit
i3c: master: Fix use-after-free of master->this
...
Diffstat (limited to 'drivers/clocksource/timer-atmel-pit.c')
| -rw-r--r-- | drivers/clocksource/timer-atmel-pit.c | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-atmel-pit.c b/drivers/clocksource/timer-atmel-pit.c new file mode 100644 index 000000000..888b06731 --- /dev/null +++ b/drivers/clocksource/timer-atmel-pit.c @@ -0,0 +1,264 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * at91sam926x_time.c - Periodic Interval Timer (PIT) for at91sam926x + * + * Copyright (C) 2005-2006 M. Amine SAYA, ATMEL Rousset, France + * Revision 2005 M. Nicolas Diremdjian, ATMEL Rousset, France + * Converted to ClockSource/ClockEvents by David Brownell. + */ + +#define pr_fmt(fmt) "AT91: PIT: " fmt + +#include <linux/clk.h> +#include <linux/clockchips.h> +#include <linux/interrupt.h> +#include <linux/irq.h> +#include <linux/kernel.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/slab.h> + +#define AT91_PIT_MR 0x00 /* Mode Register */ +#define AT91_PIT_PITIEN BIT(25) /* Timer Interrupt Enable */ +#define AT91_PIT_PITEN BIT(24) /* Timer Enabled */ +#define AT91_PIT_PIV GENMASK(19, 0) /* Periodic Interval Value */ + +#define AT91_PIT_SR 0x04 /* Status Register */ +#define AT91_PIT_PITS BIT(0) /* Timer Status */ + +#define AT91_PIT_PIVR 0x08 /* Periodic Interval Value Register */ +#define AT91_PIT_PIIR 0x0c /* Periodic Interval Image Register */ +#define AT91_PIT_PICNT GENMASK(31, 20) /* Interval Counter */ +#define AT91_PIT_CPIV GENMASK(19, 0) /* Inverval Value */ + +#define PIT_CPIV(x) ((x) & AT91_PIT_CPIV) +#define PIT_PICNT(x) (((x) & AT91_PIT_PICNT) >> 20) + +struct pit_data { + struct clock_event_device clkevt; + struct clocksource clksrc; + + void __iomem *base; + u32 cycle; + u32 cnt; + unsigned int irq; + struct clk *mck; +}; + +static inline struct pit_data *clksrc_to_pit_data(struct clocksource *clksrc) +{ + return container_of(clksrc, struct pit_data, clksrc); +} + +static inline struct pit_data *clkevt_to_pit_data(struct clock_event_device *clkevt) +{ + return container_of(clkevt, struct pit_data, clkevt); +} + +static inline unsigned int pit_read(void __iomem *base, unsigned int reg_offset) +{ + return readl_relaxed(base + reg_offset); +} + +static inline void pit_write(void __iomem *base, unsigned int reg_offset, unsigned long value) +{ + writel_relaxed(value, base + reg_offset); +} + +/* + * Clocksource: just a monotonic counter of MCK/16 cycles. + * We don't care whether or not PIT irqs are enabled. + */ +static u64 read_pit_clk(struct clocksource *cs) +{ + struct pit_data *data = clksrc_to_pit_data(cs); + unsigned long flags; + u32 elapsed; + u32 t; + + raw_local_irq_save(flags); + elapsed = data->cnt; + t = pit_read(data->base, AT91_PIT_PIIR); + raw_local_irq_restore(flags); + + elapsed += PIT_PICNT(t) * data->cycle; + elapsed += PIT_CPIV(t); + return elapsed; +} + +static int pit_clkevt_shutdown(struct clock_event_device *dev) +{ + struct pit_data *data = clkevt_to_pit_data(dev); + + /* disable irq, leaving the clocksource active */ + pit_write(data->base, AT91_PIT_MR, (data->cycle - 1) | AT91_PIT_PITEN); + return 0; +} + +/* + * Clockevent device: interrupts every 1/HZ (== pit_cycles * MCK/16) + */ +static int pit_clkevt_set_periodic(struct clock_event_device *dev) +{ + struct pit_data *data = clkevt_to_pit_data(dev); + + /* update clocksource counter */ + data->cnt += data->cycle * PIT_PICNT(pit_read(data->base, AT91_PIT_PIVR)); + pit_write(data->base, AT91_PIT_MR, + (data->cycle - 1) | AT91_PIT_PITEN | AT91_PIT_PITIEN); + return 0; +} + +static void at91sam926x_pit_suspend(struct clock_event_device *cedev) +{ + struct pit_data *data = clkevt_to_pit_data(cedev); + + /* Disable timer */ + pit_write(data->base, AT91_PIT_MR, 0); +} + +static void at91sam926x_pit_reset(struct pit_data *data) +{ + /* Disable timer and irqs */ + pit_write(data->base, AT91_PIT_MR, 0); + + /* Clear any pending interrupts, wait for PIT to stop counting */ + while (PIT_CPIV(pit_read(data->base, AT91_PIT_PIVR)) != 0) + cpu_relax(); + + /* Start PIT but don't enable IRQ */ + pit_write(data->base, AT91_PIT_MR, + (data->cycle - 1) | AT91_PIT_PITEN); +} + +static void at91sam926x_pit_resume(struct clock_event_device *cedev) +{ + struct pit_data *data = clkevt_to_pit_data(cedev); + + at91sam926x_pit_reset(data); +} + +/* + * IRQ handler for the timer. + */ +static irqreturn_t at91sam926x_pit_interrupt(int irq, void *dev_id) +{ + struct pit_data *data = dev_id; + + /* The PIT interrupt may be disabled, and is shared */ + if (clockevent_state_periodic(&data->clkevt) && + (pit_read(data->base, AT91_PIT_SR) & AT91_PIT_PITS)) { + /* Get number of ticks performed before irq, and ack it */ + data->cnt += data->cycle * PIT_PICNT(pit_read(data->base, + AT91_PIT_PIVR)); + data->clkevt.event_handler(&data->clkevt); + + return IRQ_HANDLED; + } + + return IRQ_NONE; +} + +/* + * Set up both clocksource and clockevent support. + */ +static int __init at91sam926x_pit_dt_init(struct device_node *node) +{ + unsigned long pit_rate; + unsigned bits; + int ret; + struct pit_data *data; + + data = kzalloc_obj(*data); + if (!data) + return -ENOMEM; + + data->base = of_iomap(node, 0); + if (!data->base) { + pr_err("Could not map PIT address\n"); + ret = -ENXIO; + goto exit; + } + + data->mck = of_clk_get(node, 0); + if (IS_ERR(data->mck)) { + pr_err("Unable to get mck clk\n"); + ret = PTR_ERR(data->mck); + goto exit; + } + + ret = clk_prepare_enable(data->mck); + if (ret) { + pr_err("Unable to enable mck\n"); + goto exit; + } + + /* Get the interrupts property */ + data->irq = irq_of_parse_and_map(node, 0); + if (!data->irq) { + pr_err("Unable to get IRQ from DT\n"); + ret = -EINVAL; + goto exit; + } + + /* + * Use our actual MCK to figure out how many MCK/16 ticks per + * 1/HZ period (instead of a compile-time constant LATCH). + */ + pit_rate = clk_get_rate(data->mck) / 16; + data->cycle = DIV_ROUND_CLOSEST(pit_rate, HZ); + WARN_ON(((data->cycle - 1) & ~AT91_PIT_PIV) != 0); + + /* Initialize and enable the timer */ + at91sam926x_pit_reset(data); + + /* + * Register clocksource. The high order bits of PIV are unused, + * so this isn't a 32-bit counter unless we get clockevent irqs. + */ + bits = 12 /* PICNT */ + ilog2(data->cycle) /* PIV */; + data->clksrc.mask = CLOCKSOURCE_MASK(bits); + data->clksrc.name = "pit"; + data->clksrc.rating = 175; + data->clksrc.read = read_pit_clk; + data->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS; + + ret = clocksource_register_hz(&data->clksrc, pit_rate); + if (ret) { + pr_err("Failed to register clocksource\n"); + goto exit; + } + + /* Set up irq handler */ + ret = request_irq(data->irq, at91sam926x_pit_interrupt, + IRQF_SHARED | IRQF_TIMER | IRQF_IRQPOLL, + "at91_tick", data); + if (ret) { + pr_err("Unable to setup IRQ\n"); + clocksource_unregister(&data->clksrc); + goto exit; + } + + /* Set up and register clockevents */ + data->clkevt.name = "pit"; + data->clkevt.features = CLOCK_EVT_FEAT_PERIODIC; + data->clkevt.shift = 32; + data->clkevt.mult = div_sc(pit_rate, NSEC_PER_SEC, data->clkevt.shift); + data->clkevt.rating = 100; + data->clkevt.cpumask = cpumask_of(0); + + data->clkevt.set_state_shutdown = pit_clkevt_shutdown; + data->clkevt.set_state_periodic = pit_clkevt_set_periodic; + data->clkevt.resume = at91sam926x_pit_resume; + data->clkevt.suspend = at91sam926x_pit_suspend; + clockevents_register_device(&data->clkevt); + + return 0; + +exit: + kfree(data); + return ret; +} +TIMER_OF_DECLARE(at91sam926x_pit, "atmel,at91sam9260-pit", + at91sam926x_pit_dt_init); |
