| // 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/err.h> |
| #include <linux/ioport.h> |
| #include <linux/io.h> |
| #include <linux/platform_device.h> |
| #include <linux/syscore_ops.h> |
| #include <linux/atmel_tc.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 16-bit clockevent |
| * source, used in either periodic or oneshot mode. This runs |
| * at 32 KiHZ, and can handle delays of up to two seconds. |
| * |
| * A boot clocksource and clockevent source are also currently needed, |
| * unless the relevant platforms (ARM/AT91, AVR32/AT32) are changed so |
| * this code can be used when init_timers() is called, well before most |
| * devices are set up. (Some low end AT91 parts, which can run uClinux, |
| * have only the timers in one TC block... they currently don't support |
| * the tclib code, because of that initialization issue.) |
| * |
| * 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 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 = { |
| .name = "tcb_clksrc", |
| .rating = 200, |
| .read = tc_get_cycles, |
| .mask = CLOCKSOURCE_MASK(32), |
| .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
| .suspend = tc_clksrc_suspend, |
| .resume = tc_clksrc_resume, |
| }; |
| |
| #ifdef CONFIG_GENERIC_CLOCKEVENTS |
| |
| struct tc_clkevt_device { |
| struct clock_event_device clkevt; |
| struct clk *clk; |
| 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); |
| } |
| |
| /* For now, we always use the 32K clock ... this optimizes for NO_HZ, |
| * because using one of the divided clocks would usually mean the |
| * tick rate can never be less than several dozen Hz (vs 0.5 Hz). |
| * |
| * A divided clock could be good for high resolution timers, since |
| * 30.5 usec resolution can seem "low". |
| */ |
| 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); |
| |
| /* slow clock, 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); |
| |
| /* slow clock, 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((32768 + 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 = { |
| .name = "tc_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 clk32k_divisor_idx) |
| { |
| int ret; |
| struct clk *t2_clk = tc->clk[2]; |
| int irq = tc->irq[2]; |
| |
| ret = clk_prepare_enable(tc->slow_clk); |
| if (ret) |
| return ret; |
| |
| /* try to enable t2 clk to avoid future errors in mode change */ |
| ret = clk_prepare_enable(t2_clk); |
| if (ret) { |
| clk_disable_unprepare(tc->slow_clk); |
| return ret; |
| } |
| |
| clk_disable(t2_clk); |
| |
| clkevt.regs = tc->regs; |
| clkevt.clk = t2_clk; |
| |
| timer_clock = clk32k_divisor_idx; |
| |
| clkevt.clkevt.cpumask = cpumask_of(0); |
| |
| ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt); |
| if (ret) { |
| clk_unprepare(t2_clk); |
| clk_disable_unprepare(tc->slow_clk); |
| return ret; |
| } |
| |
| clockevents_config_and_register(&clkevt.clkevt, 32768, 1, 0xffff); |
| |
| return ret; |
| } |
| |
| #else /* !CONFIG_GENERIC_CLOCKEVENTS */ |
| |
| static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_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_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 int __init tcb_clksrc_init(void) |
| { |
| static char bootinfo[] __initdata |
| = KERN_DEBUG "%s: tc%d at %d.%03d MHz\n"; |
| |
| struct platform_device *pdev; |
| struct atmel_tc *tc; |
| struct clk *t0_clk; |
| u32 rate, divided_rate = 0; |
| int best_divisor_idx = -1; |
| int clk32k_divisor_idx = -1; |
| int i; |
| int ret; |
| |
| tc = atmel_tc_alloc(CONFIG_ATMEL_TCB_CLKSRC_BLOCK); |
| if (!tc) { |
| pr_debug("can't alloc TC for clocksource\n"); |
| return -ENODEV; |
| } |
| tcaddr = tc->regs; |
| pdev = tc->pdev; |
| |
| t0_clk = tc->clk[0]; |
| ret = clk_prepare_enable(t0_clk); |
| if (ret) { |
| pr_debug("can't enable T0 clk\n"); |
| goto err_free_tc; |
| } |
| |
| /* How fast will we be counting? Pick something over 5 MHz. */ |
| rate = (u32) clk_get_rate(t0_clk); |
| for (i = 0; i < 5; i++) { |
| unsigned divisor = atmel_tc_divisors[i]; |
| unsigned tmp; |
| |
| /* remember 32 KiHz clock for later */ |
| if (!divisor) { |
| clk32k_divisor_idx = i; |
| continue; |
| } |
| |
| tmp = rate / divisor; |
| pr_debug("TC: %u / %-3u [%d] --> %u\n", rate, divisor, i, tmp); |
| if (best_divisor_idx > 0) { |
| if (tmp < 5 * 1000 * 1000) |
| continue; |
| } |
| divided_rate = tmp; |
| best_divisor_idx = i; |
| } |
| |
| |
| printk(bootinfo, clksrc.name, CONFIG_ATMEL_TCB_CLKSRC_BLOCK, |
| divided_rate / 1000000, |
| ((divided_rate % 1000000) + 500) / 1000); |
| |
| if (tc->tcb_config && tc->tcb_config->counter_width == 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); |
| } else { |
| /* tclib will give us 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); |
| } |
| |
| /* 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, clk32k_divisor_idx); |
| if (ret) |
| goto err_unregister_clksrc; |
| |
| return 0; |
| |
| err_unregister_clksrc: |
| clocksource_unregister(&clksrc); |
| |
| err_disable_t1: |
| if (!tc->tcb_config || tc->tcb_config->counter_width != 32) |
| clk_disable_unprepare(tc->clk[1]); |
| |
| err_disable_t0: |
| clk_disable_unprepare(t0_clk); |
| |
| err_free_tc: |
| atmel_tc_free(tc); |
| return ret; |
| } |
| arch_initcall(tcb_clksrc_init); |