kernel/printk: Convert to hotplug state machine

[linux/fpc-iii.git] / drivers / clocksource / tcb_clksrc.c

#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).
 *   - 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 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 cycle_t tc_get_cycles32(struct clocksource *cs)
{
        return __raw_readl(tcaddr + ATMEL_TC_REG(0, CV));
}

static struct clocksource clksrc = {
        .name           = "tcb_clksrc",
        .rating         = 200,
        .read           = tc_get_cycles,
        .mask           = CLOCKSOURCE_MASK(32),
        .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 int tc_shutdown(struct clock_event_device *d)
{
        struct tc_clkevt_device *tcd = to_tc_clkevt(d);
        void __iomem            *regs = tcd->regs;

        __raw_writel(0xff, regs + ATMEL_TC_REG(2, IDR));
        __raw_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 */
        __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 */
        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 */
        __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));
        return 0;
}

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,
                /* 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 = __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 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 */
        __raw_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));
        __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*/
        __raw_writel(ATMEL_TC_TC1XC1S_TIOA0, tcaddr + ATMEL_TC_BMR);
        /* then reset all the timers */
        __raw_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 */
        __raw_writel(mck_divisor_idx                    /* likely divide-by-8 */
                        | ATMEL_TC_WAVE
                        | ATMEL_TC_WAVESEL_UP,          /* free-run */
                        tcaddr + ATMEL_TC_REG(0, CMR));
        __raw_writel(0xff, tcaddr + ATMEL_TC_REG(0, IDR));      /* no irqs */
        __raw_writel(ATMEL_TC_CLKEN, tcaddr + ATMEL_TC_REG(0, CCR));

        /* then reset all the timers */
        __raw_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 + 500000) % 1000000) / 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);