diff options
author | Keguang Zhang <keguang.zhang@gmail.com> | 2023-05-12 13:37:24 +0300 |
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committer | Daniel Lezcano <daniel.lezcano@linaro.org> | 2023-06-19 18:07:03 +0300 |
commit | e738521a11f13e40af89f66527e59306c4169782 (patch) | |
tree | 7029c7cf4e587975eae19ca57a5b61727366b62f /drivers/clocksource/timer-loongson1-pwm.c | |
parent | b25efff2a63f0d573f409f22e82904db9cc7d577 (diff) | |
download | linux-e738521a11f13e40af89f66527e59306c4169782.tar.xz |
clocksource/drivers/loongson1: Move PWM timer to clocksource framework
This patch moves most part of arch/mips/loongson32/common/time.c
into drivers/clocksource.
Adapt the driver to clocksource framework with devicetree support
and updates Kconfig/Makefile options.
Signed-off-by: Keguang Zhang <keguang.zhang@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230512103724.587760-4-keguang.zhang@gmail.com
Diffstat (limited to 'drivers/clocksource/timer-loongson1-pwm.c')
-rw-r--r-- | drivers/clocksource/timer-loongson1-pwm.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-loongson1-pwm.c b/drivers/clocksource/timer-loongson1-pwm.c new file mode 100644 index 000000000000..6335fee03017 --- /dev/null +++ b/drivers/clocksource/timer-loongson1-pwm.c @@ -0,0 +1,236 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Clocksource driver for Loongson-1 SoC + * + * Copyright (c) 2023 Keguang Zhang <keguang.zhang@gmail.com> + */ + +#include <linux/clockchips.h> +#include <linux/interrupt.h> +#include <linux/sizes.h> +#include "timer-of.h" + +/* Loongson-1 PWM Timer Register Definitions */ +#define PWM_CNTR 0x0 +#define PWM_HRC 0x4 +#define PWM_LRC 0x8 +#define PWM_CTRL 0xc + +/* PWM Control Register Bits */ +#define INT_LRC_EN BIT(11) +#define INT_HRC_EN BIT(10) +#define CNTR_RST BIT(7) +#define INT_SR BIT(6) +#define INT_EN BIT(5) +#define PWM_SINGLE BIT(4) +#define PWM_OE BIT(3) +#define CNT_EN BIT(0) + +#define CNTR_WIDTH 24 + +DEFINE_RAW_SPINLOCK(ls1x_timer_lock); + +struct ls1x_clocksource { + void __iomem *reg_base; + unsigned long ticks_per_jiffy; + struct clocksource clksrc; +}; + +static inline struct ls1x_clocksource *to_ls1x_clksrc(struct clocksource *c) +{ + return container_of(c, struct ls1x_clocksource, clksrc); +} + +static inline void ls1x_pwmtimer_set_period(unsigned int period, + struct timer_of *to) +{ + writel(period, timer_of_base(to) + PWM_LRC); + writel(period, timer_of_base(to) + PWM_HRC); +} + +static inline void ls1x_pwmtimer_clear(struct timer_of *to) +{ + writel(0, timer_of_base(to) + PWM_CNTR); +} + +static inline void ls1x_pwmtimer_start(struct timer_of *to) +{ + writel((INT_EN | PWM_OE | CNT_EN), timer_of_base(to) + PWM_CTRL); +} + +static inline void ls1x_pwmtimer_stop(struct timer_of *to) +{ + writel(0, timer_of_base(to) + PWM_CTRL); +} + +static inline void ls1x_pwmtimer_irq_ack(struct timer_of *to) +{ + int val; + + val = readl(timer_of_base(to) + PWM_CTRL); + val |= INT_SR; + writel(val, timer_of_base(to) + PWM_CTRL); +} + +static irqreturn_t ls1x_clockevent_isr(int irq, void *dev_id) +{ + struct clock_event_device *clkevt = dev_id; + struct timer_of *to = to_timer_of(clkevt); + + ls1x_pwmtimer_irq_ack(to); + ls1x_pwmtimer_clear(to); + ls1x_pwmtimer_start(to); + + clkevt->event_handler(clkevt); + + return IRQ_HANDLED; +} + +static int ls1x_clockevent_set_state_periodic(struct clock_event_device *clkevt) +{ + struct timer_of *to = to_timer_of(clkevt); + + raw_spin_lock(&ls1x_timer_lock); + ls1x_pwmtimer_set_period(timer_of_period(to), to); + ls1x_pwmtimer_clear(to); + ls1x_pwmtimer_start(to); + raw_spin_unlock(&ls1x_timer_lock); + + return 0; +} + +static int ls1x_clockevent_tick_resume(struct clock_event_device *clkevt) +{ + raw_spin_lock(&ls1x_timer_lock); + ls1x_pwmtimer_start(to_timer_of(clkevt)); + raw_spin_unlock(&ls1x_timer_lock); + + return 0; +} + +static int ls1x_clockevent_set_state_shutdown(struct clock_event_device *clkevt) +{ + raw_spin_lock(&ls1x_timer_lock); + ls1x_pwmtimer_stop(to_timer_of(clkevt)); + raw_spin_unlock(&ls1x_timer_lock); + + return 0; +} + +static int ls1x_clockevent_set_next(unsigned long evt, + struct clock_event_device *clkevt) +{ + struct timer_of *to = to_timer_of(clkevt); + + raw_spin_lock(&ls1x_timer_lock); + ls1x_pwmtimer_set_period(evt, to); + ls1x_pwmtimer_clear(to); + ls1x_pwmtimer_start(to); + raw_spin_unlock(&ls1x_timer_lock); + + return 0; +} + +static struct timer_of ls1x_to = { + .flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK, + .clkevt = { + .name = "ls1x-pwmtimer", + .features = CLOCK_EVT_FEAT_PERIODIC | + CLOCK_EVT_FEAT_ONESHOT, + .rating = 300, + .set_next_event = ls1x_clockevent_set_next, + .set_state_periodic = ls1x_clockevent_set_state_periodic, + .set_state_oneshot = ls1x_clockevent_set_state_shutdown, + .set_state_shutdown = ls1x_clockevent_set_state_shutdown, + .tick_resume = ls1x_clockevent_tick_resume, + }, + .of_irq = { + .handler = ls1x_clockevent_isr, + .flags = IRQF_TIMER, + }, +}; + +/* + * Since the PWM timer overflows every two ticks, its not very useful + * to just read by itself. So use jiffies to emulate a free + * running counter: + */ +static u64 ls1x_clocksource_read(struct clocksource *cs) +{ + struct ls1x_clocksource *ls1x_cs = to_ls1x_clksrc(cs); + unsigned long flags; + int count; + u32 jifs; + static int old_count; + static u32 old_jifs; + + raw_spin_lock_irqsave(&ls1x_timer_lock, flags); + /* + * Although our caller may have the read side of xtime_lock, + * this is now a seqlock, and we are cheating in this routine + * by having side effects on state that we cannot undo if + * there is a collision on the seqlock and our caller has to + * retry. (Namely, old_jifs and old_count.) So we must treat + * jiffies as volatile despite the lock. We read jiffies + * before latching the timer count to guarantee that although + * the jiffies value might be older than the count (that is, + * the counter may underflow between the last point where + * jiffies was incremented and the point where we latch the + * count), it cannot be newer. + */ + jifs = jiffies; + /* read the count */ + count = readl(ls1x_cs->reg_base + PWM_CNTR); + + /* + * It's possible for count to appear to go the wrong way for this + * reason: + * + * The timer counter underflows, but we haven't handled the resulting + * interrupt and incremented jiffies yet. + * + * Previous attempts to handle these cases intelligently were buggy, so + * we just do the simple thing now. + */ + if (count < old_count && jifs == old_jifs) + count = old_count; + + old_count = count; + old_jifs = jifs; + + raw_spin_unlock_irqrestore(&ls1x_timer_lock, flags); + + return (u64)(jifs * ls1x_cs->ticks_per_jiffy) + count; +} + +static struct ls1x_clocksource ls1x_clocksource = { + .clksrc = { + .name = "ls1x-pwmtimer", + .rating = 300, + .read = ls1x_clocksource_read, + .mask = CLOCKSOURCE_MASK(CNTR_WIDTH), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + }, +}; + +static int __init ls1x_pwm_clocksource_init(struct device_node *np) +{ + struct timer_of *to = &ls1x_to; + int ret; + + ret = timer_of_init(np, to); + if (ret) + return ret; + + clockevents_config_and_register(&to->clkevt, timer_of_rate(to), + 0x1, GENMASK(CNTR_WIDTH - 1, 0)); + + ls1x_clocksource.reg_base = timer_of_base(to); + ls1x_clocksource.ticks_per_jiffy = timer_of_period(to); + + return clocksource_register_hz(&ls1x_clocksource.clksrc, + timer_of_rate(to)); +} + +TIMER_OF_DECLARE(ls1x_pwm_clocksource, "loongson,ls1b-pwmtimer", + ls1x_pwm_clocksource_init); |