// SPDX-License-Identifier: GPL-2.0/* * 64-bit Periodic Interval Timer driver * * Copyright (C) 2019 Microchip Technology Inc. and its subsidiaries * * Author: Claudiu Beznea <claudiu.beznea@microchip.com> */ #include <linux/clk.h>#include <linux/clockchips.h>#include <linux/interrupt.h>#include <linux/of_address.h>#include <linux/of_irq.h>#include <linux/sched_clock.h>#include <linux/slab.h> #define MCHP_PIT64B_CR 0x00 /* Control Register */#define MCHP_PIT64B_CR_START BIT(0)#define MCHP_PIT64B_CR_SWRST BIT(8) #define MCHP_PIT64B_MR 0x04 /* Mode Register */#define MCHP_PIT64B_MR_CONT BIT(0)#define MCHP_PIT64B_MR_ONE_SHOT (0)#define MCHP_PIT64B_MR_SGCLK BIT(3)#define MCHP_PIT64B_MR_PRES GENMASK(11, 8) #define MCHP_PIT64B_LSB_PR 0x08 /* LSB Period Register */ #define MCHP_PIT64B_MSB_PR 0x0C /* MSB Period Register */ #define MCHP_PIT64B_IER 0x10 /* Interrupt Enable Register */#define MCHP_PIT64B_IER_PERIOD BIT(0) #define MCHP_PIT64B_ISR 0x1C /* Interrupt Status Register */ #define MCHP_PIT64B_TLSBR 0x20 /* Timer LSB Register */ #define MCHP_PIT64B_TMSBR 0x24 /* Timer MSB Register */ #define MCHP_PIT64B_PRES_MAX 0x10#define MCHP_PIT64B_LSBMASK GENMASK_ULL(31, 0)#define MCHP_PIT64B_PRES_TO_MODE(p) (MCHP_PIT64B_MR_PRES & ((p) << 8))#define MCHP_PIT64B_MODE_TO_PRES(m) ((MCHP_PIT64B_MR_PRES & (m)) >> 8)#define MCHP_PIT64B_DEF_FREQ 5000000UL /* 5 MHz */ #define MCHP_PIT64B_NAME "pit64b" /** * struct mchp_pit64b_timer - PIT64B timer data structure * @base: base address of PIT64B hardware block * @pclk: PIT64B's peripheral clock * @gclk: PIT64B's generic clock * @mode: precomputed value for mode register */struct mchp_pit64b_timer { void __iomem *base; struct clk *pclk; struct clk *gclk; u32 mode;}; /** * struct mchp_pit64b_clkevt - PIT64B clockevent data structure * @timer: PIT64B timer * @clkevt: clockevent */struct mchp_pit64b_clkevt { struct mchp_pit64b_timer timer; struct clock_event_device clkevt;}; #define clkevt_to_mchp_pit64b_timer(x) \ ((struct mchp_pit64b_timer *)container_of(x,\ struct mchp_pit64b_clkevt, clkevt)) /** * struct mchp_pit64b_clksrc - PIT64B clocksource data structure * @timer: PIT64B timer * @clksrc: clocksource */struct mchp_pit64b_clksrc { struct mchp_pit64b_timer timer; struct clocksource clksrc;}; #define clksrc_to_mchp_pit64b_timer(x) \ ((struct mchp_pit64b_timer *)container_of(x,\ struct mchp_pit64b_clksrc, clksrc)) /* Base address for clocksource timer. */static void __iomem *mchp_pit64b_cs_base;/* Default cycles for clockevent timer. */static u64 mchp_pit64b_ce_cycles; static inline u64 mchp_pit64b_cnt_read(void __iomem *base){ unsigned long flags; u32 low, high; raw_local_irq_save(flags); /* * When using a 64 bit period TLSB must be read first, followed by the * read of TMSB. This sequence generates an atomic read of the 64 bit * timer value whatever the lapse of time between the accesses. */ low = readl_relaxed(base + MCHP_PIT64B_TLSBR); high = readl_relaxed(base + MCHP_PIT64B_TMSBR); raw_local_irq_restore(flags); return (((u64)high << 32) | low);} static inline void mchp_pit64b_reset(struct mchp_pit64b_timer *timer, u64 cycles, u32 mode, u32 irqs){ u32 low, high; low = cycles & MCHP_PIT64B_LSBMASK; high = cycles >> 32; writel_relaxed(MCHP_PIT64B_CR_SWRST, timer->base + MCHP_PIT64B_CR); writel_relaxed(mode | timer->mode, timer->base + MCHP_PIT64B_MR); writel_relaxed(high, timer->base + MCHP_PIT64B_MSB_PR); writel_relaxed(low, timer->base + MCHP_PIT64B_LSB_PR); writel_relaxed(irqs, timer->base + MCHP_PIT64B_IER); writel_relaxed(MCHP_PIT64B_CR_START, timer->base + MCHP_PIT64B_CR);} static void mchp_pit64b_suspend(struct mchp_pit64b_timer *timer){ writel_relaxed(MCHP_PIT64B_CR_SWRST, timer->base + MCHP_PIT64B_CR); if (timer->mode & MCHP_PIT64B_MR_SGCLK) clk_disable_unprepare(timer->gclk); clk_disable_unprepare(timer->pclk);} static void mchp_pit64b_resume(struct mchp_pit64b_timer *timer){ clk_prepare_enable(timer->pclk); if (timer->mode & MCHP_PIT64B_MR_SGCLK) clk_prepare_enable(timer->gclk);} static void mchp_pit64b_clksrc_suspend(struct clocksource *cs){ struct mchp_pit64b_timer *timer = clksrc_to_mchp_pit64b_timer(cs); mchp_pit64b_suspend(timer);} static void mchp_pit64b_clksrc_resume(struct clocksource *cs){ struct mchp_pit64b_timer *timer = clksrc_to_mchp_pit64b_timer(cs); mchp_pit64b_resume(timer); mchp_pit64b_reset(timer, ULLONG_MAX, MCHP_PIT64B_MR_CONT, 0);} static u64 mchp_pit64b_clksrc_read(struct clocksource *cs){ return mchp_pit64b_cnt_read(mchp_pit64b_cs_base);} static u64 notrace mchp_pit64b_sched_read_clk(void){ return mchp_pit64b_cnt_read(mchp_pit64b_cs_base);} static int mchp_pit64b_clkevt_shutdown(struct clock_event_device *cedev){ struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev); if (!clockevent_state_detached(cedev)) mchp_pit64b_suspend(timer); return 0;} static int mchp_pit64b_clkevt_set_periodic(struct clock_event_device *cedev){ struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev); if (clockevent_state_shutdown(cedev)) mchp_pit64b_resume(timer); mchp_pit64b_reset(timer, mchp_pit64b_ce_cycles, MCHP_PIT64B_MR_CONT, MCHP_PIT64B_IER_PERIOD); return 0;} static int mchp_pit64b_clkevt_set_oneshot(struct clock_event_device *cedev){ struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev); if (clockevent_state_shutdown(cedev)) mchp_pit64b_resume(timer); mchp_pit64b_reset(timer, mchp_pit64b_ce_cycles, MCHP_PIT64B_MR_ONE_SHOT, MCHP_PIT64B_IER_PERIOD); return 0;} static int mchp_pit64b_clkevt_set_next_event(unsigned long evt, struct clock_event_device *cedev){ struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev); mchp_pit64b_reset(timer, evt, MCHP_PIT64B_MR_ONE_SHOT, MCHP_PIT64B_IER_PERIOD); return 0;} static irqreturn_t mchp_pit64b_interrupt(int irq, void *dev_id){ struct mchp_pit64b_clkevt *irq_data = dev_id; /* Need to clear the interrupt. */ readl_relaxed(irq_data->timer.base + MCHP_PIT64B_ISR); irq_data->clkevt.event_handler(&irq_data->clkevt); return IRQ_HANDLED;} static void __init mchp_pit64b_pres_compute(u32 *pres, u32 clk_rate, u32 max_rate){ u32 tmp; for (*pres = 0; *pres < MCHP_PIT64B_PRES_MAX; (*pres)++) { tmp = clk_rate / (*pres + 1); if (tmp <= max_rate) break; } /* Use the biggest prescaler if we didn't match one. */ if (*pres == MCHP_PIT64B_PRES_MAX) *pres = MCHP_PIT64B_PRES_MAX - 1;} /** * mchp_pit64b_init_mode() - prepare PIT64B mode register value to be used at * runtime; this includes prescaler and SGCLK bit * @timer: pointer to pit64b timer to init * @max_rate: maximum rate that timer's clock could use * * PIT64B timer may be fed by gclk or pclk. When gclk is used its rate has to * be at least 3 times lower that pclk's rate. pclk rate is fixed, gclk rate * could be changed via clock APIs. The chosen clock (pclk or gclk) could be * divided by the internal PIT64B's divider. * * This function, first tries to use GCLK by requesting the desired rate from * PMC and then using the internal PIT64B prescaler, if any, to reach the * requested rate. If PCLK/GCLK < 3 (condition requested by PIT64B hardware) * then the function falls back on using PCLK as clock source for PIT64B timer * choosing the highest prescaler in case it doesn't locate one to match the * requested frequency. * * Below is presented the PIT64B block in relation with PMC: * * PIT64B * PMC +------------------------------------+ * +----+ | +-----+ | * | |-->gclk -->|-->| | +---------+ +-----+ | * | | | | MUX |--->| Divider |->|timer| | * | |-->pclk -->|-->| | +---------+ +-----+ | * +----+ | +-----+ | * | ^ | * | sel | * +------------------------------------+ * * Where: * - gclk rate <= pclk rate/3 * - gclk rate could be requested from PMC * - pclk rate is fixed (cannot be requested from PMC) */static int __init mchp_pit64b_init_mode(struct mchp_pit64b_timer *timer, unsigned long max_rate){ unsigned long pclk_rate, diff = 0, best_diff = ULONG_MAX; long gclk_round = 0; u32 pres, best_pres = 0; pclk_rate = clk_get_rate(timer->pclk); if (!pclk_rate) return -EINVAL; timer->mode = 0; /* Try using GCLK. */ gclk_round = clk_round_rate(timer->gclk, max_rate); if (gclk_round < 0) goto pclk; if (pclk_rate / gclk_round < 3) goto pclk; mchp_pit64b_pres_compute(&pres, gclk_round, max_rate); best_diff = abs(gclk_round / (pres + 1) - max_rate); best_pres = pres; if (!best_diff) { timer->mode |= MCHP_PIT64B_MR_SGCLK; clk_set_rate(timer->gclk, gclk_round); goto done; } pclk: /* Check if requested rate could be obtained using PCLK. */ mchp_pit64b_pres_compute(&pres, pclk_rate, max_rate); diff = abs(pclk_rate / (pres + 1) - max_rate); if (best_diff > diff) { /* Use PCLK. */ best_pres = pres; } else { /* Use GCLK. */ timer->mode |= MCHP_PIT64B_MR_SGCLK; clk_set_rate(timer->gclk, gclk_round); } done: timer->mode |= MCHP_PIT64B_PRES_TO_MODE(best_pres); pr_info("PIT64B: using clk=%s with prescaler %u, freq=%lu [Hz]\n", timer->mode & MCHP_PIT64B_MR_SGCLK ? "gclk" : "pclk", best_pres, timer->mode & MCHP_PIT64B_MR_SGCLK ? gclk_round / (best_pres + 1) : pclk_rate / (best_pres + 1)); return 0;} static int __init mchp_pit64b_init_clksrc(struct mchp_pit64b_timer *timer, u32 clk_rate){ struct mchp_pit64b_clksrc *cs; int ret; cs = kzalloc(sizeof(*cs), GFP_KERNEL); if (!cs) return -ENOMEM; mchp_pit64b_resume(timer); mchp_pit64b_reset(timer, ULLONG_MAX, MCHP_PIT64B_MR_CONT, 0); mchp_pit64b_cs_base = timer->base; cs->timer.base = timer->base; cs->timer.pclk = timer->pclk; cs->timer.gclk = timer->gclk; cs->timer.mode = timer->mode; cs->clksrc.name = MCHP_PIT64B_NAME; cs->clksrc.mask = CLOCKSOURCE_MASK(64); cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS; cs->clksrc.rating = 210; cs->clksrc.read = mchp_pit64b_clksrc_read; cs->clksrc.suspend = mchp_pit64b_clksrc_suspend; cs->clksrc.resume = mchp_pit64b_clksrc_resume; ret = clocksource_register_hz(&cs->clksrc, clk_rate); if (ret) { pr_debug("clksrc: Failed to register PIT64B clocksource!\n"); /* Stop timer. */ mchp_pit64b_suspend(timer); kfree(cs); return ret; } sched_clock_register(mchp_pit64b_sched_read_clk, 64, clk_rate); return 0;} static int __init mchp_pit64b_init_clkevt(struct mchp_pit64b_timer *timer, u32 clk_rate, u32 irq){ struct mchp_pit64b_clkevt *ce; int ret; ce = kzalloc(sizeof(*ce), GFP_KERNEL); if (!ce) return -ENOMEM; mchp_pit64b_ce_cycles = DIV_ROUND_CLOSEST(clk_rate, HZ); ce->timer.base = timer->base; ce->timer.pclk = timer->pclk; ce->timer.gclk = timer->gclk; ce->timer.mode = timer->mode; ce->clkevt.name = MCHP_PIT64B_NAME; ce->clkevt.features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC; ce->clkevt.rating = 150; ce->clkevt.set_state_shutdown = mchp_pit64b_clkevt_shutdown; ce->clkevt.set_state_periodic = mchp_pit64b_clkevt_set_periodic; ce->clkevt.set_state_oneshot = mchp_pit64b_clkevt_set_oneshot; ce->clkevt.set_next_event = mchp_pit64b_clkevt_set_next_event; ce->clkevt.cpumask = cpumask_of(0); ce->clkevt.irq = irq; ret = request_irq(irq, mchp_pit64b_interrupt, IRQF_TIMER, "pit64b_tick", ce); if (ret) { pr_debug("clkevt: Failed to setup PIT64B IRQ\n"); kfree(ce); return ret; } clockevents_config_and_register(&ce->clkevt, clk_rate, 1, ULONG_MAX); return 0;} static int __init mchp_pit64b_dt_init_timer(struct device_node *node, bool clkevt){ struct mchp_pit64b_timer timer; unsigned long clk_rate; u32 irq = 0; int ret; /* Parse DT node. */ timer.pclk = of_clk_get_by_name(node, "pclk"); if (IS_ERR(timer.pclk)) return PTR_ERR(timer.pclk); timer.gclk = of_clk_get_by_name(node, "gclk"); if (IS_ERR(timer.gclk)) return PTR_ERR(timer.gclk); timer.base = of_iomap(node, 0); if (!timer.base) return -ENXIO; if (clkevt) { irq = irq_of_parse_and_map(node, 0); if (!irq) { ret = -ENODEV; goto io_unmap; } } /* Initialize mode (prescaler + SGCK bit). To be used at runtime. */ ret = mchp_pit64b_init_mode(&timer, MCHP_PIT64B_DEF_FREQ); if (ret) goto irq_unmap; if (timer.mode & MCHP_PIT64B_MR_SGCLK) clk_rate = clk_get_rate(timer.gclk); else clk_rate = clk_get_rate(timer.pclk); clk_rate = clk_rate / (MCHP_PIT64B_MODE_TO_PRES(timer.mode) + 1); if (clkevt) ret = mchp_pit64b_init_clkevt(&timer, clk_rate, irq); else ret = mchp_pit64b_init_clksrc(&timer, clk_rate); if (ret) goto irq_unmap; return 0; irq_unmap: irq_dispose_mapping(irq);io_unmap: iounmap(timer.base); return ret;} static int __init mchp_pit64b_dt_init(struct device_node *node){ static int inits; switch (inits++) { case 0: /* 1st request, register clockevent. */ return mchp_pit64b_dt_init_timer(node, true); case 1: /* 2nd request, register clocksource. */ return mchp_pit64b_dt_init_timer(node, false); } /* The rest, don't care. */ return -EINVAL;} TIMER_OF_DECLARE(mchp_pit64b, "microchip,sam9x60-pit64b", mchp_pit64b_dt_init);
// SPDX-License-Identifier: GPL-2.0
/*
* 64-bit Periodic Interval Timer driver
*
* Copyright (C) 2019 Microchip Technology Inc. and its subsidiaries
*
* Author: Claudiu Beznea <claudiu.beznea@microchip.com>
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/sched_clock.h>
#include <linux/slab.h>
#define MCHP_PIT64B_CR 0x00 /* Control Register */
#define MCHP_PIT64B_CR_START BIT(0)
#define MCHP_PIT64B_CR_SWRST BIT(8)
#define MCHP_PIT64B_MR 0x04 /* Mode Register */
#define MCHP_PIT64B_MR_CONT BIT(0)
#define MCHP_PIT64B_MR_ONE_SHOT (0)
#define MCHP_PIT64B_MR_SGCLK BIT(3)
#define MCHP_PIT64B_MR_PRES GENMASK(11, 8)
#define MCHP_PIT64B_LSB_PR 0x08 /* LSB Period Register */
#define MCHP_PIT64B_MSB_PR 0x0C /* MSB Period Register */
#define MCHP_PIT64B_IER 0x10 /* Interrupt Enable Register */
#define MCHP_PIT64B_IER_PERIOD BIT(0)
#define MCHP_PIT64B_ISR 0x1C /* Interrupt Status Register */
#define MCHP_PIT64B_TLSBR 0x20 /* Timer LSB Register */
#define MCHP_PIT64B_TMSBR 0x24 /* Timer MSB Register */
#define MCHP_PIT64B_PRES_MAX 0x10
#define MCHP_PIT64B_LSBMASK GENMASK_ULL(31, 0)
#define MCHP_PIT64B_PRES_TO_MODE(p) (MCHP_PIT64B_MR_PRES & ((p) << 8))
#define MCHP_PIT64B_MODE_TO_PRES(m) ((MCHP_PIT64B_MR_PRES & (m)) >> 8)
#define MCHP_PIT64B_DEF_FREQ 5000000UL /* 5 MHz */
#define MCHP_PIT64B_NAME "pit64b"
/**
* struct mchp_pit64b_timer - PIT64B timer data structure
* @base: base address of PIT64B hardware block
* @pclk: PIT64B's peripheral clock
* @gclk: PIT64B's generic clock
* @mode: precomputed value for mode register
*/
struct mchp_pit64b_timer {
void __iomem *base;
struct clk *pclk;
struct clk *gclk;
u32 mode;
};
/**
* struct mchp_pit64b_clkevt - PIT64B clockevent data structure
* @timer: PIT64B timer
* @clkevt: clockevent
*/
struct mchp_pit64b_clkevt {
struct mchp_pit64b_timer timer;
struct clock_event_device clkevt;
};
#define clkevt_to_mchp_pit64b_timer(x) \
((struct mchp_pit64b_timer *)container_of(x,\
struct mchp_pit64b_clkevt, clkevt))
/**
* struct mchp_pit64b_clksrc - PIT64B clocksource data structure
* @timer: PIT64B timer
* @clksrc: clocksource
*/
struct mchp_pit64b_clksrc {
struct mchp_pit64b_timer timer;
struct clocksource clksrc;
};
#define clksrc_to_mchp_pit64b_timer(x) \
((struct mchp_pit64b_timer *)container_of(x,\
struct mchp_pit64b_clksrc, clksrc))
/* Base address for clocksource timer. */
static void __iomem *mchp_pit64b_cs_base;
/* Default cycles for clockevent timer. */
static u64 mchp_pit64b_ce_cycles;
static inline u64 mchp_pit64b_cnt_read(void __iomem *base)
{
unsigned long flags;
u32 low, high;
raw_local_irq_save(flags);
/*
* When using a 64 bit period TLSB must be read first, followed by the
* read of TMSB. This sequence generates an atomic read of the 64 bit
* timer value whatever the lapse of time between the accesses.
*/
low = readl_relaxed(base + MCHP_PIT64B_TLSBR);
high = readl_relaxed(base + MCHP_PIT64B_TMSBR);
raw_local_irq_restore(flags);
return (((u64)high << 32) | low);
}
static inline void mchp_pit64b_reset(struct mchp_pit64b_timer *timer,
u64 cycles, u32 mode, u32 irqs)
{
u32 low, high;
low = cycles & MCHP_PIT64B_LSBMASK;
high = cycles >> 32;
writel_relaxed(MCHP_PIT64B_CR_SWRST, timer->base + MCHP_PIT64B_CR);
writel_relaxed(mode | timer->mode, timer->base + MCHP_PIT64B_MR);
writel_relaxed(high, timer->base + MCHP_PIT64B_MSB_PR);
writel_relaxed(low, timer->base + MCHP_PIT64B_LSB_PR);
writel_relaxed(irqs, timer->base + MCHP_PIT64B_IER);
writel_relaxed(MCHP_PIT64B_CR_START, timer->base + MCHP_PIT64B_CR);
}
static void mchp_pit64b_suspend(struct mchp_pit64b_timer *timer)
{
writel_relaxed(MCHP_PIT64B_CR_SWRST, timer->base + MCHP_PIT64B_CR);
if (timer->mode & MCHP_PIT64B_MR_SGCLK)
clk_disable_unprepare(timer->gclk);
clk_disable_unprepare(timer->pclk);
}
static void mchp_pit64b_resume(struct mchp_pit64b_timer *timer)
{
clk_prepare_enable(timer->pclk);
if (timer->mode & MCHP_PIT64B_MR_SGCLK)
clk_prepare_enable(timer->gclk);
}
static void mchp_pit64b_clksrc_suspend(struct clocksource *cs)
{
struct mchp_pit64b_timer *timer = clksrc_to_mchp_pit64b_timer(cs);
mchp_pit64b_suspend(timer);
}
static void mchp_pit64b_clksrc_resume(struct clocksource *cs)
{
struct mchp_pit64b_timer *timer = clksrc_to_mchp_pit64b_timer(cs);
mchp_pit64b_resume(timer);
mchp_pit64b_reset(timer, ULLONG_MAX, MCHP_PIT64B_MR_CONT, 0);
}
static u64 mchp_pit64b_clksrc_read(struct clocksource *cs)
{
return mchp_pit64b_cnt_read(mchp_pit64b_cs_base);
}
static u64 notrace mchp_pit64b_sched_read_clk(void)
{
return mchp_pit64b_cnt_read(mchp_pit64b_cs_base);
}
static int mchp_pit64b_clkevt_shutdown(struct clock_event_device *cedev)
{
struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev);
if (!clockevent_state_detached(cedev))
mchp_pit64b_suspend(timer);
return 0;
}
static int mchp_pit64b_clkevt_set_periodic(struct clock_event_device *cedev)
{
struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev);
if (clockevent_state_shutdown(cedev))
mchp_pit64b_resume(timer);
mchp_pit64b_reset(timer, mchp_pit64b_ce_cycles, MCHP_PIT64B_MR_CONT,
MCHP_PIT64B_IER_PERIOD);
return 0;
}
static int mchp_pit64b_clkevt_set_oneshot(struct clock_event_device *cedev)
{
struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev);
if (clockevent_state_shutdown(cedev))
mchp_pit64b_resume(timer);
mchp_pit64b_reset(timer, mchp_pit64b_ce_cycles, MCHP_PIT64B_MR_ONE_SHOT,
MCHP_PIT64B_IER_PERIOD);
return 0;
}
static int mchp_pit64b_clkevt_set_next_event(unsigned long evt,
struct clock_event_device *cedev)
{
struct mchp_pit64b_timer *timer = clkevt_to_mchp_pit64b_timer(cedev);
mchp_pit64b_reset(timer, evt, MCHP_PIT64B_MR_ONE_SHOT,
MCHP_PIT64B_IER_PERIOD);
return 0;
}
static irqreturn_t mchp_pit64b_interrupt(int irq, void *dev_id)
{
struct mchp_pit64b_clkevt *irq_data = dev_id;
/* Need to clear the interrupt. */
readl_relaxed(irq_data->timer.base + MCHP_PIT64B_ISR);
irq_data->clkevt.event_handler(&irq_data->clkevt);
return IRQ_HANDLED;
}
static void __init mchp_pit64b_pres_compute(u32 *pres, u32 clk_rate,
u32 max_rate)
{
u32 tmp;
for (*pres = 0; *pres < MCHP_PIT64B_PRES_MAX; (*pres)++) {
tmp = clk_rate / (*pres + 1);
if (tmp <= max_rate)
break;
}
/* Use the biggest prescaler if we didn't match one. */
if (*pres == MCHP_PIT64B_PRES_MAX)
*pres = MCHP_PIT64B_PRES_MAX - 1;
}
/**
* mchp_pit64b_init_mode() - prepare PIT64B mode register value to be used at
* runtime; this includes prescaler and SGCLK bit
* @timer: pointer to pit64b timer to init
* @max_rate: maximum rate that timer's clock could use
*
* PIT64B timer may be fed by gclk or pclk. When gclk is used its rate has to
* be at least 3 times lower that pclk's rate. pclk rate is fixed, gclk rate
* could be changed via clock APIs. The chosen clock (pclk or gclk) could be
* divided by the internal PIT64B's divider.
*
* This function, first tries to use GCLK by requesting the desired rate from
* PMC and then using the internal PIT64B prescaler, if any, to reach the
* requested rate. If PCLK/GCLK < 3 (condition requested by PIT64B hardware)
* then the function falls back on using PCLK as clock source for PIT64B timer
* choosing the highest prescaler in case it doesn't locate one to match the
* requested frequency.
*
* Below is presented the PIT64B block in relation with PMC:
*
* PIT64B
* PMC +------------------------------------+
* +----+ | +-----+ |
* | |-->gclk -->|-->| | +---------+ +-----+ |
* | | | | MUX |--->| Divider |->|timer| |
* | |-->pclk -->|-->| | +---------+ +-----+ |
* +----+ | +-----+ |
* | ^ |
* | sel |
* +------------------------------------+
*
* Where:
* - gclk rate <= pclk rate/3
* - gclk rate could be requested from PMC
* - pclk rate is fixed (cannot be requested from PMC)
*/
static int __init mchp_pit64b_init_mode(struct mchp_pit64b_timer *timer,
unsigned long max_rate)
{
unsigned long pclk_rate, diff = 0, best_diff = ULONG_MAX;
long gclk_round = 0;
u32 pres, best_pres = 0;
pclk_rate = clk_get_rate(timer->pclk);
if (!pclk_rate)
return -EINVAL;
timer->mode = 0;
/* Try using GCLK. */
gclk_round = clk_round_rate(timer->gclk, max_rate);
if (gclk_round < 0)
goto pclk;
if (pclk_rate / gclk_round < 3)
goto pclk;
mchp_pit64b_pres_compute(&pres, gclk_round, max_rate);
best_diff = abs(gclk_round / (pres + 1) - max_rate);
best_pres = pres;
if (!best_diff) {
timer->mode |= MCHP_PIT64B_MR_SGCLK;
clk_set_rate(timer->gclk, gclk_round);
goto done;
}
pclk:
/* Check if requested rate could be obtained using PCLK. */
mchp_pit64b_pres_compute(&pres, pclk_rate, max_rate);
diff = abs(pclk_rate / (pres + 1) - max_rate);
if (best_diff > diff) {
/* Use PCLK. */
best_pres = pres;
} else {
/* Use GCLK. */
timer->mode |= MCHP_PIT64B_MR_SGCLK;
clk_set_rate(timer->gclk, gclk_round);
}
done:
timer->mode |= MCHP_PIT64B_PRES_TO_MODE(best_pres);
pr_info("PIT64B: using clk=%s with prescaler %u, freq=%lu [Hz]\n",
timer->mode & MCHP_PIT64B_MR_SGCLK ? "gclk" : "pclk", best_pres,
timer->mode & MCHP_PIT64B_MR_SGCLK ?
gclk_round / (best_pres + 1) : pclk_rate / (best_pres + 1));
return 0;
}
static int __init mchp_pit64b_init_clksrc(struct mchp_pit64b_timer *timer,
u32 clk_rate)
{
struct mchp_pit64b_clksrc *cs;
int ret;
cs = kzalloc(sizeof(*cs), GFP_KERNEL);
if (!cs)
return -ENOMEM;
mchp_pit64b_resume(timer);
mchp_pit64b_reset(timer, ULLONG_MAX, MCHP_PIT64B_MR_CONT, 0);
mchp_pit64b_cs_base = timer->base;
cs->timer.base = timer->base;
cs->timer.pclk = timer->pclk;
cs->timer.gclk = timer->gclk;
cs->timer.mode = timer->mode;
cs->clksrc.name = MCHP_PIT64B_NAME;
cs->clksrc.mask = CLOCKSOURCE_MASK(64);
cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS;
cs->clksrc.rating = 210;
cs->clksrc.read = mchp_pit64b_clksrc_read;
cs->clksrc.suspend = mchp_pit64b_clksrc_suspend;
cs->clksrc.resume = mchp_pit64b_clksrc_resume;
ret = clocksource_register_hz(&cs->clksrc, clk_rate);
if (ret) {
pr_debug("clksrc: Failed to register PIT64B clocksource!\n");
/* Stop timer. */
mchp_pit64b_suspend(timer);
kfree(cs);
return ret;
}
sched_clock_register(mchp_pit64b_sched_read_clk, 64, clk_rate);
return 0;
}
static int __init mchp_pit64b_init_clkevt(struct mchp_pit64b_timer *timer,
u32 clk_rate, u32 irq)
{
struct mchp_pit64b_clkevt *ce;
int ret;
ce = kzalloc(sizeof(*ce), GFP_KERNEL);
if (!ce)
return -ENOMEM;
mchp_pit64b_ce_cycles = DIV_ROUND_CLOSEST(clk_rate, HZ);
ce->timer.base = timer->base;
ce->timer.pclk = timer->pclk;
ce->timer.gclk = timer->gclk;
ce->timer.mode = timer->mode;
ce->clkevt.name = MCHP_PIT64B_NAME;
ce->clkevt.features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC;
ce->clkevt.rating = 150;
ce->clkevt.set_state_shutdown = mchp_pit64b_clkevt_shutdown;
ce->clkevt.set_state_periodic = mchp_pit64b_clkevt_set_periodic;
ce->clkevt.set_state_oneshot = mchp_pit64b_clkevt_set_oneshot;
ce->clkevt.set_next_event = mchp_pit64b_clkevt_set_next_event;
ce->clkevt.cpumask = cpumask_of(0);
ce->clkevt.irq = irq;
ret = request_irq(irq, mchp_pit64b_interrupt, IRQF_TIMER,
"pit64b_tick", ce);
if (ret) {
pr_debug("clkevt: Failed to setup PIT64B IRQ\n");
kfree(ce);
return ret;
}
clockevents_config_and_register(&ce->clkevt, clk_rate, 1, ULONG_MAX);
return 0;
}
static int __init mchp_pit64b_dt_init_timer(struct device_node *node,
bool clkevt)
{
struct mchp_pit64b_timer timer;
unsigned long clk_rate;
u32 irq = 0;
int ret;
/* Parse DT node. */
timer.pclk = of_clk_get_by_name(node, "pclk");
if (IS_ERR(timer.pclk))
return PTR_ERR(timer.pclk);
timer.gclk = of_clk_get_by_name(node, "gclk");
if (IS_ERR(timer.gclk))
return PTR_ERR(timer.gclk);
timer.base = of_iomap(node, 0);
if (!timer.base)
return -ENXIO;
if (clkevt) {
irq = irq_of_parse_and_map(node, 0);
if (!irq) {
ret = -ENODEV;
goto io_unmap;
}
}
/* Initialize mode (prescaler + SGCK bit). To be used at runtime. */
ret = mchp_pit64b_init_mode(&timer, MCHP_PIT64B_DEF_FREQ);
if (ret)
goto irq_unmap;
if (timer.mode & MCHP_PIT64B_MR_SGCLK)
clk_rate = clk_get_rate(timer.gclk);
else
clk_rate = clk_get_rate(timer.pclk);
clk_rate = clk_rate / (MCHP_PIT64B_MODE_TO_PRES(timer.mode) + 1);
if (clkevt)
ret = mchp_pit64b_init_clkevt(&timer, clk_rate, irq);
else
ret = mchp_pit64b_init_clksrc(&timer, clk_rate);
if (ret)
goto irq_unmap;
return 0;
irq_unmap:
irq_dispose_mapping(irq);
io_unmap:
iounmap(timer.base);
return ret;
}
static int __init mchp_pit64b_dt_init(struct device_node *node)
{
static int inits;
switch (inits++) {
case 0:
/* 1st request, register clockevent. */
return mchp_pit64b_dt_init_timer(node, true);
case 1:
/* 2nd request, register clocksource. */
return mchp_pit64b_dt_init_timer(node, false);
}
/* The rest, don't care. */
return -EINVAL;
}
TIMER_OF_DECLARE(mchp_pit64b, "microchip,sam9x60-pit64b", mchp_pit64b_dt_init);