#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/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). * * - 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 cycle_t tc_get_cycles(struct clocksource *cs) { unsigned long flags; u32 lower, upper; raw_local_irq_save(flags); do { upper = __raw_readl(tcaddr + ATMEL_TC_REG(1, CV)); lower = __raw_readl(tcaddr + ATMEL_TC_REG(0, CV)); } while (upper != __raw_readl(tcaddr + ATMEL_TC_REG(1, CV))); raw_local_irq_restore(flags); return (upper << 16) | lower; } static struct clocksource clksrc = { .name = "tcb_clksrc", .rating = 200, .read = tc_get_cycles, .mask = CLOCKSOURCE_MASK(32), .shift = 18, .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; #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 void tc_mode(enum clock_event_mode m, struct clock_event_device *d) { struct tc_clkevt_device *tcd = to_tc_clkevt(d); void __iomem *regs = tcd->regs; if (tcd->clkevt.mode == CLOCK_EVT_MODE_PERIODIC || tcd->clkevt.mode == CLOCK_EVT_MODE_ONESHOT) { __raw_writel(0xff, regs + ATMEL_TC_REG(2, IDR)); __raw_writel(ATMEL_TC_CLKDIS, regs + ATMEL_TC_REG(2, CCR)); clk_disable(tcd->clk); } switch (m) { /* By not making the gentime core emulate periodic mode on top * of oneshot, we get lower overhead and improved accuracy. */ case CLOCK_EVT_MODE_PERIODIC: clk_enable(tcd->clk); /* slow clock, count up to RC, then irq and restart */ __raw_writel(timer_clock | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO, regs + ATMEL_TC_REG(2, CMR)); __raw_writel((32768 + HZ/2) / HZ, tcaddr + ATMEL_TC_REG(2, RC)); /* Enable clock and interrupts on RC compare */ __raw_writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); /* go go gadget! */ __raw_writel(ATMEL_TC_CLKEN | ATMEL_TC_SWTRG, regs + ATMEL_TC_REG(2, CCR)); break; case CLOCK_EVT_MODE_ONESHOT: clk_enable(tcd->clk); /* slow clock, count up to RC, then irq and stop */ __raw_writel(timer_clock | ATMEL_TC_CPCSTOP | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP_AUTO, regs + ATMEL_TC_REG(2, CMR)); __raw_writel(ATMEL_TC_CPCS, regs + ATMEL_TC_REG(2, IER)); /* set_next_event() configures and starts the timer */ break; default: break; } } static int tc_next_event(unsigned long delta, struct clock_event_device *d) { __raw_writel(delta, tcaddr + ATMEL_TC_REG(2, RC)); /* go go gadget! */ __raw_writel(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, .shift = 32, /* Should be lower than at91rm9200's system timer */ .rating = 125, .set_next_event = tc_next_event, .set_mode = tc_mode, }, }; static irqreturn_t ch2_irq(int irq, void *handle) { struct tc_clkevt_device *dev = handle; unsigned int sr; sr = __raw_readl(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 struct irqaction tc_irqaction = { .name = "tc_clkevt", .flags = IRQF_TIMER | IRQF_DISABLED, .handler = ch2_irq, }; static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx) { struct clk *t2_clk = tc->clk[2]; int irq = tc->irq[2]; clkevt.regs = tc->regs; clkevt.clk = t2_clk; tc_irqaction.dev_id = &clkevt; timer_clock = clk32k_divisor_idx; clkevt.clkevt.mult = div_sc(32768, NSEC_PER_SEC, clkevt.clkevt.shift); clkevt.clkevt.max_delta_ns = clockevent_delta2ns(0xffff, &clkevt.clkevt); clkevt.clkevt.min_delta_ns = clockevent_delta2ns(1, &clkevt.clkevt) + 1; clkevt.clkevt.cpumask = cpumask_of(0); setup_irq(irq, &tc_irqaction); clockevents_register_device(&clkevt.clkevt); } #else /* !CONFIG_GENERIC_CLOCKEVENTS */ static void __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx) { /* NOTHING */ } #endif 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; tc = atmel_tc_alloc(CONFIG_ATMEL_TCB_CLKSRC_BLOCK, clksrc.name); if (!tc) { pr_debug("can't alloc TC for clocksource\n"); return -ENODEV; } tcaddr = tc->regs; pdev = tc->pdev; t0_clk = tc->clk[0]; clk_enable(t0_clk); /* 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; } clksrc.mult = clocksource_hz2mult(divided_rate, clksrc.shift); printk(bootinfo, clksrc.name, CONFIG_ATMEL_TCB_CLKSRC_BLOCK, divided_rate / 1000000, ((divided_rate + 500000) % 1000000) / 1000); /* tclib will give us three clocks no matter what the * underlying platform supports. */ clk_enable(tc->clk[1]); /* channel 0: waveform mode, input mclk/8, clock TIOA0 on overflow */ __raw_writel(best_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)); __raw_writel(0x0000, tcaddr + ATMEL_TC_REG(0, RA)); __raw_writel(0x8000, tcaddr + ATMEL_TC_REG(0, RC)); __raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR)); /* no irqs */ __raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR)); /* channel 1: waveform mode, input TIOA0 */ __raw_writel(ATMEL_TC_XC1 /* input: TIOA0 */ | ATMEL_TC_WAVE | ATMEL_TC_WAVESEL_UP, /* free-run */ tcaddr + ATMEL_TC_REG(1, CMR)); __raw_writel(0xff, tcaddr + ATMEL_TC_REG(1, IDR)); /* no irqs */ __raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(1, CCR)); /* chain channel 0 to channel 1, then reset all the timers */ __raw_writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR); __raw_writel(ATMEL_TC_SYNC, tcaddr + ATMEL_TC_BCR); /* and away we go! */ clocksource_register(&clksrc); /* channel 2: periodic and oneshot timer support */ setup_clkevents(tc, clk32k_divisor_idx); return 0; } arch_initcall(tcb_clksrc_init);