diff options
Diffstat (limited to 'drivers/clocksource/timer-atmel-tcb.c')
| -rw-r--r-- | drivers/clocksource/timer-atmel-tcb.c | 511 |
1 files changed, 511 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-atmel-tcb.c b/drivers/clocksource/timer-atmel-tcb.c new file mode 100644 index 000000000..5ea1efd87 --- /dev/null +++ b/drivers/clocksource/timer-atmel-tcb.c @@ -0,0 +1,511 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/init.h> +#include <linux/clocksource.h> +#include <linux/clockchips.h> +#include <linux/interrupt.h> +#include <linux/irq.h> + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/ioport.h> +#include <linux/io.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/sched_clock.h> +#include <linux/syscore_ops.h> +#include <soc/at91/atmel_tcb.h> + + +/* + * We're configured to use a specific TC block, one that's not hooked + * up to external hardware, to provide a time solution: + * + * - Two channels combine to create a free-running 32 bit counter + * with a base rate of 5+ MHz, packaged as a clocksource (with + * resolution better than 200 nsec). + * - Some chips support 32 bit counter. A single channel is used for + * this 32 bit free-running counter. the second channel is not used. + * + * - The third channel may be used to provide a clockevent source, used in + * either periodic or oneshot mode. For 16-bit counter its runs at 32 KiHZ, + * and can handle delays of up to two seconds. For 32-bit counters, it runs at + * the same rate as the clocksource + * + * REVISIT behavior during system suspend states... we should disable + * all clocks and save the power. Easily done for clockevent devices, + * but clocksources won't necessarily get the needed notifications. + * For deeper system sleep states, this will be mandatory... + */ + +static void __iomem *tcaddr; +static struct +{ + u32 cmr; + u32 imr; + u32 rc; + bool clken; +} tcb_cache[3]; +static u32 bmr_cache; + +static const u8 atmel_tcb_divisors[] = { 2, 8, 32, 128 }; + +static u64 tc_get_cycles(struct clocksource *cs) +{ + unsigned long flags; + u32 lower, upper; + + raw_local_irq_save(flags); + do { + upper = readl_relaxed(tcaddr + ATMEL_TC_REG(1, CV)); + lower = readl_relaxed(tcaddr + ATMEL_TC_REG(0, CV)); + } while (upper != readl_relaxed(tcaddr + ATMEL_TC_REG(1, CV))); + + raw_local_irq_restore(flags); + return (upper << 16) | lower; +} + +static u64 tc_get_cycles32(struct clocksource *cs) +{ + return readl_relaxed(tcaddr + ATMEL_TC_REG(0, CV)); +} + +static void tc_clksrc_suspend(struct clocksource *cs) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(tcb_cache); i++) { + tcb_cache[i].cmr = readl(tcaddr + ATMEL_TC_REG(i, CMR)); + tcb_cache[i].imr = readl(tcaddr + ATMEL_TC_REG(i, IMR)); + tcb_cache[i].rc = readl(tcaddr + ATMEL_TC_REG(i, RC)); + tcb_cache[i].clken = !!(readl(tcaddr + ATMEL_TC_REG(i, SR)) & + ATMEL_TC_CLKSTA); + } + + bmr_cache = readl(tcaddr + ATMEL_TC_BMR); +} + +static void tc_clksrc_resume(struct clocksource *cs) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(tcb_cache); i++) { + /* Restore registers for the channel, RA and RB are not used */ + writel(tcb_cache[i].cmr, tcaddr + ATMEL_TC_REG(i, CMR)); + writel(tcb_cache[i].rc, tcaddr + ATMEL_TC_REG(i, RC)); + writel(0, tcaddr + ATMEL_TC_REG(i, RA)); + writel(0, tcaddr + ATMEL_TC_REG(i, RB)); + /* Disable all the interrupts */ + writel(0xff, tcaddr + ATMEL_TC_REG(i, IDR)); + /* Reenable interrupts that were enabled before suspending */ + writel(tcb_cache[i].imr, tcaddr + ATMEL_TC_REG(i, IER)); + /* Start the clock if it was used */ + if (tcb_cache[i].clken) + writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(i, CCR)); + } + + /* Dual channel, chain channels */ + writel(bmr_cache, tcaddr + ATMEL_TC_BMR); + /* Finally, trigger all the channels*/ + writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); +} + +static struct clocksource clksrc = { + .rating = 200, + .read = tc_get_cycles, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .suspend = tc_clksrc_suspend, + .resume = tc_clksrc_resume, +}; + +static u64 notrace tc_sched_clock_read(void) +{ + return tc_get_cycles(&clksrc); +} + +static u64 notrace tc_sched_clock_read32(void) +{ + return tc_get_cycles32(&clksrc); +} + +static struct delay_timer tc_delay_timer; + +static unsigned long tc_delay_timer_read(void) +{ + return tc_get_cycles(&clksrc); +} + +static unsigned long notrace tc_delay_timer_read32(void) +{ + return tc_get_cycles32(&clksrc); +} + +#ifdef CONFIG_GENERIC_CLOCKEVENTS + +struct tc_clkevt_device { + struct clock_event_device clkevt; + struct clk *clk; + u32 rate; + void __iomem *regs; +}; + +static struct tc_clkevt_device *to_tc_clkevt(struct clock_event_device *clkevt) +{ + return container_of(clkevt, struct tc_clkevt_device, clkevt); +} + +static u32 timer_clock; + +static int tc_shutdown(struct clock_event_device *d) +{ + struct tc_clkevt_device *tcd = to_tc_clkevt(d); + void __iomem *regs = tcd->regs; + + writel(0xff, regs + ATMEL_TC_REG(2, IDR)); + writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR)); + if (!clockevent_state_detached(d)) + clk_disable(tcd->clk); + + return 0; +} + +static int tc_set_oneshot(struct clock_event_device *d) +{ + struct tc_clkevt_device *tcd = to_tc_clkevt(d); + void __iomem *regs = tcd->regs; + + if (clockevent_state_oneshot(d) || clockevent_state_periodic(d)) + tc_shutdown(d); + + clk_enable(tcd->clk); + + /* count up to RC, then irq and stop */ + writel(timer_clock | ATMEL_TC_CPCSTOP | ATMEL_TC_WAVE | + ATMEL_TC_WAVESEL_UP_AUTO, regs + ATMEL_TC_REG(2, CMR)); + writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); + + /* set_next_event() configures and starts the timer */ + return 0; +} + +static int tc_set_periodic(struct clock_event_device *d) +{ + struct tc_clkevt_device *tcd = to_tc_clkevt(d); + void __iomem *regs = tcd->regs; + + if (clockevent_state_oneshot(d) || clockevent_state_periodic(d)) + tc_shutdown(d); + + /* By not making the gentime core emulate periodic mode on top + * of oneshot, we get lower overhead and improved accuracy. + */ + clk_enable(tcd->clk); + + /* count up to RC, then irq and restart */ + writel(timer_clock | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO, + regs + ATMEL_TC_REG(2, CMR)); + writel((tcd->rate + HZ / 2) / HZ, tcaddr + ATMEL_TC_REG(2, RC)); + + /* Enable clock and interrupts on RC compare */ + writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); + + /* go go gadget! */ + writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, regs + + ATMEL_TC_REG(2, CCR)); + return 0; +} + +static int tc_next_event(unsigned long delta, struct clock_event_device *d) +{ + writel_relaxed(delta, tcaddr + ATMEL_TC_REG(2, RC)); + + /* go go gadget! */ + writel_relaxed(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, + tcaddr + ATMEL_TC_REG(2, CCR)); + return 0; +} + +static struct tc_clkevt_device clkevt = { + .clkevt = { + .features = CLOCK_EVT_FEAT_PERIODIC | + CLOCK_EVT_FEAT_ONESHOT, + /* Should be lower than at91rm9200's system timer */ + .rating = 125, + .set_next_event = tc_next_event, + .set_state_shutdown = tc_shutdown, + .set_state_periodic = tc_set_periodic, + .set_state_oneshot = tc_set_oneshot, + }, +}; + +static irqreturn_t ch2_irq(int irq, void *handle) +{ + struct tc_clkevt_device *dev = handle; + unsigned int sr; + + sr = readl_relaxed(dev->regs + ATMEL_TC_REG(2, SR)); + if (sr & ATMEL_TC_CPCS) { + dev->clkevt.event_handler(&dev->clkevt); + return IRQ_HANDLED; + } + + return IRQ_NONE; +} + +static int __init setup_clkevents(struct atmel_tc *tc, int divisor_idx) +{ + int ret; + struct clk *t2_clk = tc->clk[2]; + int irq = tc->irq[2]; + int bits = tc->tcb_config->counter_width; + + /* try to enable t2 clk to avoid future errors in mode change */ + ret = clk_prepare_enable(t2_clk); + if (ret) + return ret; + + clkevt.regs = tc->regs; + clkevt.clk = t2_clk; + + if (bits == 32) { + timer_clock = divisor_idx; + clkevt.rate = clk_get_rate(t2_clk) / atmel_tcb_divisors[divisor_idx]; + } else { + ret = clk_prepare_enable(tc->slow_clk); + if (ret) { + clk_disable_unprepare(t2_clk); + return ret; + } + + clkevt.rate = clk_get_rate(tc->slow_clk); + timer_clock = ATMEL_TC_TIMER_CLOCK5; + } + + clk_disable(t2_clk); + + clkevt.clkevt.cpumask = cpumask_of(0); + + ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt); + if (ret) { + clk_unprepare(t2_clk); + if (bits != 32) + clk_disable_unprepare(tc->slow_clk); + return ret; + } + + clockevents_config_and_register(&clkevt.clkevt, clkevt.rate, 1, BIT(bits) - 1); + + return ret; +} + +#else /* !CONFIG_GENERIC_CLOCKEVENTS */ + +static int __init setup_clkevents(struct atmel_tc *tc, int divisor_idx) +{ + /* NOTHING */ + return 0; +} + +#endif + +static void __init tcb_setup_dual_chan(struct atmel_tc *tc, int mck_divisor_idx) +{ + /* channel 0: waveform mode, input mclk/8, clock TIOA0 on overflow */ + writel(mck_divisor_idx /* likely divide-by-8 */ + | ATMEL_TC_WAVE + | ATMEL_TC_WAVESEL_UP /* free-run */ + | ATMEL_TC_ASWTRG_SET /* TIOA0 rises at software trigger */ + | ATMEL_TC_ACPA_SET /* TIOA0 rises at 0 */ + | ATMEL_TC_ACPC_CLEAR, /* (duty cycle 50%) */ + tcaddr + ATMEL_TC_REG(0, CMR)); + writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA)); + writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC)); + writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */ + writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR)); + + /* channel 1: waveform mode, input TIOA0 */ + writel(ATMEL_TC_XC1 /* input: TIOA0 */ + | ATMEL_TC_WAVE + | ATMEL_TC_WAVESEL_UP, /* free-run */ + tcaddr + ATMEL_TC_REG(1, CMR)); + writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR)); /* no irqs */ + writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR)); + + /* chain channel 0 to channel 1*/ + writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR); + /* then reset all the timers */ + writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); +} + +static void __init tcb_setup_single_chan(struct atmel_tc *tc, int mck_divisor_idx) +{ + /* channel 0: waveform mode, input mclk/8 */ + writel(mck_divisor_idx /* likely divide-by-8 */ + | ATMEL_TC_WAVE + | ATMEL_TC_WAVESEL_UP, /* free-run */ + tcaddr + ATMEL_TC_REG(0, CMR)); + writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */ + writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR)); + + /* then reset all the timers */ + writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); +} + +static struct atmel_tcb_config tcb_rm9200_config = { + .counter_width = 16, +}; + +static struct atmel_tcb_config tcb_sam9x5_config = { + .counter_width = 32, +}; + +static struct atmel_tcb_config tcb_sama5d2_config = { + .counter_width = 32, + .has_gclk = 1, +}; + +static const struct of_device_id atmel_tcb_of_match[] = { + { .compatible = "atmel,at91rm9200-tcb", .data = &tcb_rm9200_config, }, + { .compatible = "atmel,at91sam9x5-tcb", .data = &tcb_sam9x5_config, }, + { .compatible = "atmel,sama5d2-tcb", .data = &tcb_sama5d2_config, }, + { /* sentinel */ } +}; + +static int __init tcb_clksrc_init(struct device_node *node) +{ + struct atmel_tc tc; + struct clk *t0_clk; + const struct of_device_id *match; + u64 (*tc_sched_clock)(void); + u32 rate, divided_rate = 0; + int best_divisor_idx = -1; + int bits; + int i; + int ret; + + /* Protect against multiple calls */ + if (tcaddr) + return 0; + + tc.regs = of_iomap(node->parent, 0); + if (!tc.regs) + return -ENXIO; + + t0_clk = of_clk_get_by_name(node->parent, "t0_clk"); + if (IS_ERR(t0_clk)) + return PTR_ERR(t0_clk); + + tc.slow_clk = of_clk_get_by_name(node->parent, "slow_clk"); + if (IS_ERR(tc.slow_clk)) + return PTR_ERR(tc.slow_clk); + + tc.clk[0] = t0_clk; + tc.clk[1] = of_clk_get_by_name(node->parent, "t1_clk"); + if (IS_ERR(tc.clk[1])) + tc.clk[1] = t0_clk; + tc.clk[2] = of_clk_get_by_name(node->parent, "t2_clk"); + if (IS_ERR(tc.clk[2])) + tc.clk[2] = t0_clk; + + tc.irq[2] = of_irq_get(node->parent, 2); + if (tc.irq[2] <= 0) { + tc.irq[2] = of_irq_get(node->parent, 0); + if (tc.irq[2] <= 0) + return -EINVAL; + } + + match = of_match_node(atmel_tcb_of_match, node->parent); + if (!match) + return -ENODEV; + + tc.tcb_config = match->data; + bits = tc.tcb_config->counter_width; + + for (i = 0; i < ARRAY_SIZE(tc.irq); i++) + writel(ATMEL_TC_ALL_IRQ, tc.regs + ATMEL_TC_REG(i, IDR)); + + ret = clk_prepare_enable(t0_clk); + if (ret) { + pr_debug("can't enable T0 clk\n"); + return ret; + } + + /* How fast will we be counting? Pick something over 5 MHz. */ + rate = (u32) clk_get_rate(t0_clk); + i = 0; + if (tc.tcb_config->has_gclk) + i = 1; + for (; i < ARRAY_SIZE(atmel_tcb_divisors); i++) { + unsigned divisor = atmel_tcb_divisors[i]; + unsigned tmp; + + tmp = rate / divisor; + pr_debug("TC: %u / %-3u [%d] --> %u\n", rate, divisor, i, tmp); + if ((best_divisor_idx >= 0) && (tmp < 5 * 1000 * 1000)) + break; + divided_rate = tmp; + best_divisor_idx = i; + } + + clksrc.name = kbasename(node->parent->full_name); + clkevt.clkevt.name = kbasename(node->parent->full_name); + pr_debug("%s at %d.%03d MHz\n", clksrc.name, divided_rate / 1000000, + ((divided_rate % 1000000) + 500) / 1000); + + tcaddr = tc.regs; + + if (bits == 32) { + /* use apropriate function to read 32 bit counter */ + clksrc.read = tc_get_cycles32; + /* setup ony channel 0 */ + tcb_setup_single_chan(&tc, best_divisor_idx); + tc_sched_clock = tc_sched_clock_read32; + tc_delay_timer.read_current_timer = tc_delay_timer_read32; + } else { + /* we have three clocks no matter what the + * underlying platform supports. + */ + ret = clk_prepare_enable(tc.clk[1]); + if (ret) { + pr_debug("can't enable T1 clk\n"); + goto err_disable_t0; + } + /* setup both channel 0 & 1 */ + tcb_setup_dual_chan(&tc, best_divisor_idx); + tc_sched_clock = tc_sched_clock_read; + tc_delay_timer.read_current_timer = tc_delay_timer_read; + } + + /* and away we go! */ + ret = clocksource_register_hz(&clksrc, divided_rate); + if (ret) + goto err_disable_t1; + + /* channel 2: periodic and oneshot timer support */ + ret = setup_clkevents(&tc, best_divisor_idx); + if (ret) + goto err_unregister_clksrc; + + sched_clock_register(tc_sched_clock, 32, divided_rate); + + tc_delay_timer.freq = divided_rate; + register_current_timer_delay(&tc_delay_timer); + + return 0; + +err_unregister_clksrc: + clocksource_unregister(&clksrc); + +err_disable_t1: + if (bits != 32) + clk_disable_unprepare(tc.clk[1]); + +err_disable_t0: + clk_disable_unprepare(t0_clk); + + tcaddr = NULL; + + return ret; +} +TIMER_OF_DECLARE(atmel_tcb_clksrc, "atmel,tcb-timer", tcb_clksrc_init); |