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linux
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sh_cmt.c
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sh_cmt.c
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/* * 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) { unsigned long flags; if (delta > p->max_match_value) dev_warn(&p->pdev->dev, "delta out of range\n"); spin_lock_irqsave(&p->lock, flags); p->next_match_value = delta; sh_cmt_clock_event_program_verify(p, 0); 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) { struct sh_cmt_priv *p = cs_to_sh_cmt(cs); p->total_cycles = 0; return sh_cmt_start(p, FLAG_CLOCKSOURCE); } 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; /* clk_get_rate() needs an enabled clock */ clk_enable(p->clk); p->rate = clk_get_rate(p->clk) / ((p->width == 16) ? 512 : 8); clk_disable(p->clk); /* TODO: calculate good shift from rate and counter bit width */ cs->shift = 0; cs->mult = clocksource_hz2mult(p->rate, cs->shift); dev_info(&p->pdev->dev, "used as clock source\n"); clocksource_register(cs); 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");
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