/drivers/clocksource/sh_cmt.c
https://bitbucket.org/wisechild/galaxy-nexus · C · 709 lines · 506 code · 131 blank · 72 comment · 90 complexity · 42cd023284d2f44e46075a0d66a98594 MD5 · raw file
- /*
- * SuperH Timer Support - CMT
- *
- * Copyright (C) 2008 Magnus Damm
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- */
- #include <linux/init.h>
- #include <linux/platform_device.h>
- #include <linux/spinlock.h>
- #include <linux/interrupt.h>
- #include <linux/ioport.h>
- #include <linux/io.h>
- #include <linux/clk.h>
- #include <linux/irq.h>
- #include <linux/err.h>
- #include <linux/clocksource.h>
- #include <linux/clockchips.h>
- #include <linux/sh_timer.h>
- #include <linux/slab.h>
- struct sh_cmt_priv {
- void __iomem *mapbase;
- struct clk *clk;
- unsigned long width; /* 16 or 32 bit version of hardware block */
- unsigned long overflow_bit;
- unsigned long clear_bits;
- struct irqaction irqaction;
- struct platform_device *pdev;
- unsigned long flags;
- unsigned long match_value;
- unsigned long next_match_value;
- unsigned long max_match_value;
- unsigned long rate;
- spinlock_t lock;
- struct clock_event_device ced;
- struct clocksource cs;
- unsigned long total_cycles;
- };
- static DEFINE_SPINLOCK(sh_cmt_lock);
- #define CMSTR -1 /* shared register */
- #define CMCSR 0 /* channel register */
- #define CMCNT 1 /* channel register */
- #define CMCOR 2 /* channel register */
- static inline unsigned long sh_cmt_read(struct sh_cmt_priv *p, int reg_nr)
- {
- struct sh_timer_config *cfg = p->pdev->dev.platform_data;
- void __iomem *base = p->mapbase;
- unsigned long offs;
- if (reg_nr == CMSTR) {
- offs = 0;
- base -= cfg->channel_offset;
- } else
- offs = reg_nr;
- if (p->width == 16)
- offs <<= 1;
- else {
- offs <<= 2;
- if ((reg_nr == CMCNT) || (reg_nr == CMCOR))
- return ioread32(base + offs);
- }
- return ioread16(base + offs);
- }
- static inline void sh_cmt_write(struct sh_cmt_priv *p, int reg_nr,
- unsigned long value)
- {
- struct sh_timer_config *cfg = p->pdev->dev.platform_data;
- void __iomem *base = p->mapbase;
- unsigned long offs;
- if (reg_nr == CMSTR) {
- offs = 0;
- base -= cfg->channel_offset;
- } else
- offs = reg_nr;
- if (p->width == 16)
- offs <<= 1;
- else {
- offs <<= 2;
- if ((reg_nr == CMCNT) || (reg_nr == CMCOR)) {
- iowrite32(value, base + offs);
- return;
- }
- }
- iowrite16(value, base + offs);
- }
- static unsigned long sh_cmt_get_counter(struct sh_cmt_priv *p,
- int *has_wrapped)
- {
- unsigned long v1, v2, v3;
- int o1, o2;
- o1 = sh_cmt_read(p, CMCSR) & p->overflow_bit;
- /* Make sure the timer value is stable. Stolen from acpi_pm.c */
- do {
- o2 = o1;
- v1 = sh_cmt_read(p, CMCNT);
- v2 = sh_cmt_read(p, CMCNT);
- v3 = sh_cmt_read(p, CMCNT);
- o1 = sh_cmt_read(p, CMCSR) & p->overflow_bit;
- } while (unlikely((o1 != o2) || (v1 > v2 && v1 < v3)
- || (v2 > v3 && v2 < v1) || (v3 > v1 && v3 < v2)));
- *has_wrapped = o1;
- return v2;
- }
- static void sh_cmt_start_stop_ch(struct sh_cmt_priv *p, int start)
- {
- struct sh_timer_config *cfg = p->pdev->dev.platform_data;
- unsigned long flags, value;
- /* start stop register shared by multiple timer channels */
- spin_lock_irqsave(&sh_cmt_lock, flags);
- value = sh_cmt_read(p, CMSTR);
- if (start)
- value |= 1 << cfg->timer_bit;
- else
- value &= ~(1 << cfg->timer_bit);
- sh_cmt_write(p, CMSTR, value);
- spin_unlock_irqrestore(&sh_cmt_lock, flags);
- }
- static int sh_cmt_enable(struct sh_cmt_priv *p, unsigned long *rate)
- {
- int ret;
- /* enable clock */
- ret = clk_enable(p->clk);
- if (ret) {
- dev_err(&p->pdev->dev, "cannot enable clock\n");
- return ret;
- }
- /* make sure channel is disabled */
- sh_cmt_start_stop_ch(p, 0);
- /* configure channel, periodic mode and maximum timeout */
- if (p->width == 16) {
- *rate = clk_get_rate(p->clk) / 512;
- sh_cmt_write(p, CMCSR, 0x43);
- } else {
- *rate = clk_get_rate(p->clk) / 8;
- sh_cmt_write(p, CMCSR, 0x01a4);
- }
- sh_cmt_write(p, CMCOR, 0xffffffff);
- sh_cmt_write(p, CMCNT, 0);
- /* enable channel */
- sh_cmt_start_stop_ch(p, 1);
- return 0;
- }
- static void sh_cmt_disable(struct sh_cmt_priv *p)
- {
- /* disable channel */
- sh_cmt_start_stop_ch(p, 0);
- /* disable interrupts in CMT block */
- sh_cmt_write(p, CMCSR, 0);
- /* stop clock */
- clk_disable(p->clk);
- }
- /* private flags */
- #define FLAG_CLOCKEVENT (1 << 0)
- #define FLAG_CLOCKSOURCE (1 << 1)
- #define FLAG_REPROGRAM (1 << 2)
- #define FLAG_SKIPEVENT (1 << 3)
- #define FLAG_IRQCONTEXT (1 << 4)
- static void sh_cmt_clock_event_program_verify(struct sh_cmt_priv *p,
- int absolute)
- {
- unsigned long new_match;
- unsigned long value = p->next_match_value;
- unsigned long delay = 0;
- unsigned long now = 0;
- int has_wrapped;
- now = sh_cmt_get_counter(p, &has_wrapped);
- p->flags |= FLAG_REPROGRAM; /* force reprogram */
- if (has_wrapped) {
- /* we're competing with the interrupt handler.
- * -> let the interrupt handler reprogram the timer.
- * -> interrupt number two handles the event.
- */
- p->flags |= FLAG_SKIPEVENT;
- return;
- }
- if (absolute)
- now = 0;
- do {
- /* reprogram the timer hardware,
- * but don't save the new match value yet.
- */
- new_match = now + value + delay;
- if (new_match > p->max_match_value)
- new_match = p->max_match_value;
- sh_cmt_write(p, CMCOR, new_match);
- now = sh_cmt_get_counter(p, &has_wrapped);
- if (has_wrapped && (new_match > p->match_value)) {
- /* we are changing to a greater match value,
- * so this wrap must be caused by the counter
- * matching the old value.
- * -> first interrupt reprograms the timer.
- * -> interrupt number two handles the event.
- */
- p->flags |= FLAG_SKIPEVENT;
- break;
- }
- if (has_wrapped) {
- /* we are changing to a smaller match value,
- * so the wrap must be caused by the counter
- * matching the new value.
- * -> save programmed match value.
- * -> let isr handle the event.
- */
- p->match_value = new_match;
- break;
- }
- /* be safe: verify hardware settings */
- if (now < new_match) {
- /* timer value is below match value, all good.
- * this makes sure we won't miss any match events.
- * -> save programmed match value.
- * -> let isr handle the event.
- */
- p->match_value = new_match;
- break;
- }
- /* the counter has reached a value greater
- * than our new match value. and since the
- * has_wrapped flag isn't set we must have
- * programmed a too close event.
- * -> increase delay and retry.
- */
- if (delay)
- delay <<= 1;
- else
- delay = 1;
- if (!delay)
- dev_warn(&p->pdev->dev, "too long delay\n");
- } while (delay);
- }
- static void __sh_cmt_set_next(struct sh_cmt_priv *p, unsigned long delta)
- {
- if (delta > p->max_match_value)
- dev_warn(&p->pdev->dev, "delta out of range\n");
- p->next_match_value = delta;
- sh_cmt_clock_event_program_verify(p, 0);
- }
- static void sh_cmt_set_next(struct sh_cmt_priv *p, unsigned long delta)
- {
- unsigned long flags;
- spin_lock_irqsave(&p->lock, flags);
- __sh_cmt_set_next(p, delta);
- spin_unlock_irqrestore(&p->lock, flags);
- }
- static irqreturn_t sh_cmt_interrupt(int irq, void *dev_id)
- {
- struct sh_cmt_priv *p = dev_id;
- /* clear flags */
- sh_cmt_write(p, CMCSR, sh_cmt_read(p, CMCSR) & p->clear_bits);
- /* update clock source counter to begin with if enabled
- * the wrap flag should be cleared by the timer specific
- * isr before we end up here.
- */
- if (p->flags & FLAG_CLOCKSOURCE)
- p->total_cycles += p->match_value + 1;
- if (!(p->flags & FLAG_REPROGRAM))
- p->next_match_value = p->max_match_value;
- p->flags |= FLAG_IRQCONTEXT;
- if (p->flags & FLAG_CLOCKEVENT) {
- if (!(p->flags & FLAG_SKIPEVENT)) {
- if (p->ced.mode == CLOCK_EVT_MODE_ONESHOT) {
- p->next_match_value = p->max_match_value;
- p->flags |= FLAG_REPROGRAM;
- }
- p->ced.event_handler(&p->ced);
- }
- }
- p->flags &= ~FLAG_SKIPEVENT;
- if (p->flags & FLAG_REPROGRAM) {
- p->flags &= ~FLAG_REPROGRAM;
- sh_cmt_clock_event_program_verify(p, 1);
- if (p->flags & FLAG_CLOCKEVENT)
- if ((p->ced.mode == CLOCK_EVT_MODE_SHUTDOWN)
- || (p->match_value == p->next_match_value))
- p->flags &= ~FLAG_REPROGRAM;
- }
- p->flags &= ~FLAG_IRQCONTEXT;
- return IRQ_HANDLED;
- }
- static int sh_cmt_start(struct sh_cmt_priv *p, unsigned long flag)
- {
- int ret = 0;
- unsigned long flags;
- spin_lock_irqsave(&p->lock, flags);
- if (!(p->flags & (FLAG_CLOCKEVENT | FLAG_CLOCKSOURCE)))
- ret = sh_cmt_enable(p, &p->rate);
- if (ret)
- goto out;
- p->flags |= flag;
- /* setup timeout if no clockevent */
- if ((flag == FLAG_CLOCKSOURCE) && (!(p->flags & FLAG_CLOCKEVENT)))
- __sh_cmt_set_next(p, p->max_match_value);
- out:
- spin_unlock_irqrestore(&p->lock, flags);
- return ret;
- }
- static void sh_cmt_stop(struct sh_cmt_priv *p, unsigned long flag)
- {
- unsigned long flags;
- unsigned long f;
- spin_lock_irqsave(&p->lock, flags);
- f = p->flags & (FLAG_CLOCKEVENT | FLAG_CLOCKSOURCE);
- p->flags &= ~flag;
- if (f && !(p->flags & (FLAG_CLOCKEVENT | FLAG_CLOCKSOURCE)))
- sh_cmt_disable(p);
- /* adjust the timeout to maximum if only clocksource left */
- if ((flag == FLAG_CLOCKEVENT) && (p->flags & FLAG_CLOCKSOURCE))
- __sh_cmt_set_next(p, p->max_match_value);
- spin_unlock_irqrestore(&p->lock, flags);
- }
- static struct sh_cmt_priv *cs_to_sh_cmt(struct clocksource *cs)
- {
- return container_of(cs, struct sh_cmt_priv, cs);
- }
- static cycle_t sh_cmt_clocksource_read(struct clocksource *cs)
- {
- struct sh_cmt_priv *p = cs_to_sh_cmt(cs);
- unsigned long flags, raw;
- unsigned long value;
- int has_wrapped;
- spin_lock_irqsave(&p->lock, flags);
- value = p->total_cycles;
- raw = sh_cmt_get_counter(p, &has_wrapped);
- if (unlikely(has_wrapped))
- raw += p->match_value + 1;
- spin_unlock_irqrestore(&p->lock, flags);
- return value + raw;
- }
- static int sh_cmt_clocksource_enable(struct clocksource *cs)
- {
- int ret;
- struct sh_cmt_priv *p = cs_to_sh_cmt(cs);
- p->total_cycles = 0;
- ret = sh_cmt_start(p, FLAG_CLOCKSOURCE);
- if (!ret)
- __clocksource_updatefreq_hz(cs, p->rate);
- return ret;
- }
- static void sh_cmt_clocksource_disable(struct clocksource *cs)
- {
- sh_cmt_stop(cs_to_sh_cmt(cs), FLAG_CLOCKSOURCE);
- }
- static void sh_cmt_clocksource_resume(struct clocksource *cs)
- {
- sh_cmt_start(cs_to_sh_cmt(cs), FLAG_CLOCKSOURCE);
- }
- static int sh_cmt_register_clocksource(struct sh_cmt_priv *p,
- char *name, unsigned long rating)
- {
- struct clocksource *cs = &p->cs;
- cs->name = name;
- cs->rating = rating;
- cs->read = sh_cmt_clocksource_read;
- cs->enable = sh_cmt_clocksource_enable;
- cs->disable = sh_cmt_clocksource_disable;
- cs->suspend = sh_cmt_clocksource_disable;
- cs->resume = sh_cmt_clocksource_resume;
- cs->mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8);
- cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
- dev_info(&p->pdev->dev, "used as clock source\n");
- /* Register with dummy 1 Hz value, gets updated in ->enable() */
- clocksource_register_hz(cs, 1);
- return 0;
- }
- static struct sh_cmt_priv *ced_to_sh_cmt(struct clock_event_device *ced)
- {
- return container_of(ced, struct sh_cmt_priv, ced);
- }
- static void sh_cmt_clock_event_start(struct sh_cmt_priv *p, int periodic)
- {
- struct clock_event_device *ced = &p->ced;
- sh_cmt_start(p, FLAG_CLOCKEVENT);
- /* TODO: calculate good shift from rate and counter bit width */
- ced->shift = 32;
- ced->mult = div_sc(p->rate, NSEC_PER_SEC, ced->shift);
- ced->max_delta_ns = clockevent_delta2ns(p->max_match_value, ced);
- ced->min_delta_ns = clockevent_delta2ns(0x1f, ced);
- if (periodic)
- sh_cmt_set_next(p, ((p->rate + HZ/2) / HZ) - 1);
- else
- sh_cmt_set_next(p, p->max_match_value);
- }
- static void sh_cmt_clock_event_mode(enum clock_event_mode mode,
- struct clock_event_device *ced)
- {
- struct sh_cmt_priv *p = ced_to_sh_cmt(ced);
- /* deal with old setting first */
- switch (ced->mode) {
- case CLOCK_EVT_MODE_PERIODIC:
- case CLOCK_EVT_MODE_ONESHOT:
- sh_cmt_stop(p, FLAG_CLOCKEVENT);
- break;
- default:
- break;
- }
- switch (mode) {
- case CLOCK_EVT_MODE_PERIODIC:
- dev_info(&p->pdev->dev, "used for periodic clock events\n");
- sh_cmt_clock_event_start(p, 1);
- break;
- case CLOCK_EVT_MODE_ONESHOT:
- dev_info(&p->pdev->dev, "used for oneshot clock events\n");
- sh_cmt_clock_event_start(p, 0);
- break;
- case CLOCK_EVT_MODE_SHUTDOWN:
- case CLOCK_EVT_MODE_UNUSED:
- sh_cmt_stop(p, FLAG_CLOCKEVENT);
- break;
- default:
- break;
- }
- }
- static int sh_cmt_clock_event_next(unsigned long delta,
- struct clock_event_device *ced)
- {
- struct sh_cmt_priv *p = ced_to_sh_cmt(ced);
- BUG_ON(ced->mode != CLOCK_EVT_MODE_ONESHOT);
- if (likely(p->flags & FLAG_IRQCONTEXT))
- p->next_match_value = delta - 1;
- else
- sh_cmt_set_next(p, delta - 1);
- return 0;
- }
- static void sh_cmt_register_clockevent(struct sh_cmt_priv *p,
- char *name, unsigned long rating)
- {
- struct clock_event_device *ced = &p->ced;
- memset(ced, 0, sizeof(*ced));
- ced->name = name;
- ced->features = CLOCK_EVT_FEAT_PERIODIC;
- ced->features |= CLOCK_EVT_FEAT_ONESHOT;
- ced->rating = rating;
- ced->cpumask = cpumask_of(0);
- ced->set_next_event = sh_cmt_clock_event_next;
- ced->set_mode = sh_cmt_clock_event_mode;
- dev_info(&p->pdev->dev, "used for clock events\n");
- clockevents_register_device(ced);
- }
- static int sh_cmt_register(struct sh_cmt_priv *p, char *name,
- unsigned long clockevent_rating,
- unsigned long clocksource_rating)
- {
- if (p->width == (sizeof(p->max_match_value) * 8))
- p->max_match_value = ~0;
- else
- p->max_match_value = (1 << p->width) - 1;
- p->match_value = p->max_match_value;
- spin_lock_init(&p->lock);
- if (clockevent_rating)
- sh_cmt_register_clockevent(p, name, clockevent_rating);
- if (clocksource_rating)
- sh_cmt_register_clocksource(p, name, clocksource_rating);
- return 0;
- }
- static int sh_cmt_setup(struct sh_cmt_priv *p, struct platform_device *pdev)
- {
- struct sh_timer_config *cfg = pdev->dev.platform_data;
- struct resource *res;
- int irq, ret;
- ret = -ENXIO;
- memset(p, 0, sizeof(*p));
- p->pdev = pdev;
- if (!cfg) {
- dev_err(&p->pdev->dev, "missing platform data\n");
- goto err0;
- }
- platform_set_drvdata(pdev, p);
- res = platform_get_resource(p->pdev, IORESOURCE_MEM, 0);
- if (!res) {
- dev_err(&p->pdev->dev, "failed to get I/O memory\n");
- goto err0;
- }
- irq = platform_get_irq(p->pdev, 0);
- if (irq < 0) {
- dev_err(&p->pdev->dev, "failed to get irq\n");
- goto err0;
- }
- /* map memory, let mapbase point to our channel */
- p->mapbase = ioremap_nocache(res->start, resource_size(res));
- if (p->mapbase == NULL) {
- dev_err(&p->pdev->dev, "failed to remap I/O memory\n");
- goto err0;
- }
- /* request irq using setup_irq() (too early for request_irq()) */
- p->irqaction.name = dev_name(&p->pdev->dev);
- p->irqaction.handler = sh_cmt_interrupt;
- p->irqaction.dev_id = p;
- p->irqaction.flags = IRQF_DISABLED | IRQF_TIMER | \
- IRQF_IRQPOLL | IRQF_NOBALANCING;
- /* get hold of clock */
- p->clk = clk_get(&p->pdev->dev, "cmt_fck");
- if (IS_ERR(p->clk)) {
- dev_err(&p->pdev->dev, "cannot get clock\n");
- ret = PTR_ERR(p->clk);
- goto err1;
- }
- if (resource_size(res) == 6) {
- p->width = 16;
- p->overflow_bit = 0x80;
- p->clear_bits = ~0x80;
- } else {
- p->width = 32;
- p->overflow_bit = 0x8000;
- p->clear_bits = ~0xc000;
- }
- ret = sh_cmt_register(p, (char *)dev_name(&p->pdev->dev),
- cfg->clockevent_rating,
- cfg->clocksource_rating);
- if (ret) {
- dev_err(&p->pdev->dev, "registration failed\n");
- goto err1;
- }
- ret = setup_irq(irq, &p->irqaction);
- if (ret) {
- dev_err(&p->pdev->dev, "failed to request irq %d\n", irq);
- goto err1;
- }
- return 0;
- err1:
- iounmap(p->mapbase);
- err0:
- return ret;
- }
- static int __devinit sh_cmt_probe(struct platform_device *pdev)
- {
- struct sh_cmt_priv *p = platform_get_drvdata(pdev);
- int ret;
- if (p) {
- dev_info(&pdev->dev, "kept as earlytimer\n");
- return 0;
- }
- p = kmalloc(sizeof(*p), GFP_KERNEL);
- if (p == NULL) {
- dev_err(&pdev->dev, "failed to allocate driver data\n");
- return -ENOMEM;
- }
- ret = sh_cmt_setup(p, pdev);
- if (ret) {
- kfree(p);
- platform_set_drvdata(pdev, NULL);
- }
- return ret;
- }
- static int __devexit sh_cmt_remove(struct platform_device *pdev)
- {
- return -EBUSY; /* cannot unregister clockevent and clocksource */
- }
- static struct platform_driver sh_cmt_device_driver = {
- .probe = sh_cmt_probe,
- .remove = __devexit_p(sh_cmt_remove),
- .driver = {
- .name = "sh_cmt",
- }
- };
- static int __init sh_cmt_init(void)
- {
- return platform_driver_register(&sh_cmt_device_driver);
- }
- static void __exit sh_cmt_exit(void)
- {
- platform_driver_unregister(&sh_cmt_device_driver);
- }
- early_platform_init("earlytimer", &sh_cmt_device_driver);
- module_init(sh_cmt_init);
- module_exit(sh_cmt_exit);
- MODULE_AUTHOR("Magnus Damm");
- MODULE_DESCRIPTION("SuperH CMT Timer Driver");
- MODULE_LICENSE("GPL v2");