/* * Emma Mobile Timer Support - STI * * Copyright (C) 2012 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/delay.h> #include <linux/clocksource.h> #include <linux/clockchips.h> #include <linux/slab.h> #include <linux/module.h> enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR }; struct em_sti_priv { void __iomem *base; struct clk *clk; struct platform_device *pdev; unsigned int active[USER_NR]; unsigned long rate; raw_spinlock_t lock; struct clock_event_device ced; struct clocksource cs; }; #define STI_CONTROL 0x00 #define STI_COMPA_H 0x10 #define STI_COMPA_L 0x14 #define STI_COMPB_H 0x18 #define STI_COMPB_L 0x1c #define STI_COUNT_H 0x20 #define STI_COUNT_L 0x24 #define STI_COUNT_RAW_H 0x28 #define STI_COUNT_RAW_L 0x2c #define STI_SET_H 0x30 #define STI_SET_L 0x34 #define STI_INTSTATUS 0x40 #define STI_INTRAWSTATUS 0x44 #define STI_INTENSET 0x48 #define STI_INTENCLR 0x4c #define STI_INTFFCLR 0x50 static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs) { return ioread32(p->base + offs); } static inline void em_sti_write(struct em_sti_priv *p, int offs, unsigned long value) { iowrite32(value, p->base + offs); } static int em_sti_enable(struct em_sti_priv *p) { int ret; /* enable clock */ ret = clk_prepare_enable(p->clk); if (ret) { dev_err(&p->pdev->dev, "cannot enable clock\n"); return ret; } /* configure channel, periodic mode and maximum timeout */ p->rate = clk_get_rate(p->clk); /* reset the counter */ em_sti_write(p, STI_SET_H, 0x40000000); em_sti_write(p, STI_SET_L, 0x00000000); /* mask and clear pending interrupts */ em_sti_write(p, STI_INTENCLR, 3); em_sti_write(p, STI_INTFFCLR, 3); /* enable updates of counter registers */ em_sti_write(p, STI_CONTROL, 1); return 0; } static void em_sti_disable(struct em_sti_priv *p) { /* mask interrupts */ em_sti_write(p, STI_INTENCLR, 3); /* stop clock */ clk_disable_unprepare(p->clk); } static cycle_t em_sti_count(struct em_sti_priv *p) { cycle_t ticks; unsigned long flags; /* the STI hardware buffers the 48-bit count, but to * break it out into two 32-bit access the registers * must be accessed in a certain order. * Always read STI_COUNT_H before STI_COUNT_L. */ raw_spin_lock_irqsave(&p->lock, flags); ticks = (cycle_t)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32; ticks |= em_sti_read(p, STI_COUNT_L); raw_spin_unlock_irqrestore(&p->lock, flags); return ticks; } static cycle_t em_sti_set_next(struct em_sti_priv *p, cycle_t next) { unsigned long flags; raw_spin_lock_irqsave(&p->lock, flags); /* mask compare A interrupt */ em_sti_write(p, STI_INTENCLR, 1); /* update compare A value */ em_sti_write(p, STI_COMPA_H, next >> 32); em_sti_write(p, STI_COMPA_L, next & 0xffffffff); /* clear compare A interrupt source */ em_sti_write(p, STI_INTFFCLR, 1); /* unmask compare A interrupt */ em_sti_write(p, STI_INTENSET, 1); raw_spin_unlock_irqrestore(&p->lock, flags); return next; } static irqreturn_t em_sti_interrupt(int irq, void *dev_id) { struct em_sti_priv *p = dev_id; p->ced.event_handler(&p->ced); return IRQ_HANDLED; } static int em_sti_start(struct em_sti_priv *p, unsigned int user) { unsigned long flags; int used_before; int ret = 0; raw_spin_lock_irqsave(&p->lock, flags); used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; if (!used_before) ret = em_sti_enable(p); if (!ret) p->active[user] = 1; raw_spin_unlock_irqrestore(&p->lock, flags); return ret; } static void em_sti_stop(struct em_sti_priv *p, unsigned int user) { unsigned long flags; int used_before, used_after; raw_spin_lock_irqsave(&p->lock, flags); used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; p->active[user] = 0; used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; if (used_before && !used_after) em_sti_disable(p); raw_spin_unlock_irqrestore(&p->lock, flags); } static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs) { return container_of(cs, struct em_sti_priv, cs); } static cycle_t em_sti_clocksource_read(struct clocksource *cs) { return em_sti_count(cs_to_em_sti(cs)); } static int em_sti_clocksource_enable(struct clocksource *cs) { int ret; struct em_sti_priv *p = cs_to_em_sti(cs); ret = em_sti_start(p, USER_CLOCKSOURCE); if (!ret) __clocksource_update_freq_hz(cs, p->rate); return ret; } static void em_sti_clocksource_disable(struct clocksource *cs) { em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE); } static void em_sti_clocksource_resume(struct clocksource *cs) { em_sti_clocksource_enable(cs); } static int em_sti_register_clocksource(struct em_sti_priv *p) { struct clocksource *cs = &p->cs; cs->name = dev_name(&p->pdev->dev); cs->rating = 200; cs->read = em_sti_clocksource_read; cs->enable = em_sti_clocksource_enable; cs->disable = em_sti_clocksource_disable; cs->suspend = em_sti_clocksource_disable; cs->resume = em_sti_clocksource_resume; cs->mask = CLOCKSOURCE_MASK(48); 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 em_sti_priv *ced_to_em_sti(struct clock_event_device *ced) { return container_of(ced, struct em_sti_priv, ced); } static int em_sti_clock_event_shutdown(struct clock_event_device *ced) { struct em_sti_priv *p = ced_to_em_sti(ced); em_sti_stop(p, USER_CLOCKEVENT); return 0; } static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced) { struct em_sti_priv *p = ced_to_em_sti(ced); dev_info(&p->pdev->dev, "used for oneshot clock events\n"); em_sti_start(p, USER_CLOCKEVENT); clockevents_config(&p->ced, p->rate); return 0; } static int em_sti_clock_event_next(unsigned long delta, struct clock_event_device *ced) { struct em_sti_priv *p = ced_to_em_sti(ced); cycle_t next; int safe; next = em_sti_set_next(p, em_sti_count(p) + delta); safe = em_sti_count(p) < (next - 1); return !safe; } static void em_sti_register_clockevent(struct em_sti_priv *p) { struct clock_event_device *ced = &p->ced; ced->name = dev_name(&p->pdev->dev); ced->features = CLOCK_EVT_FEAT_ONESHOT; ced->rating = 200; ced->cpumask = cpu_possible_mask; ced->set_next_event = em_sti_clock_event_next; ced->set_state_shutdown = em_sti_clock_event_shutdown; ced->set_state_oneshot = em_sti_clock_event_set_oneshot; dev_info(&p->pdev->dev, "used for clock events\n"); /* Register with dummy 1 Hz value, gets updated in ->set_state_oneshot() */ clockevents_config_and_register(ced, 1, 2, 0xffffffff); } static int em_sti_probe(struct platform_device *pdev) { struct em_sti_priv *p; struct resource *res; int irq; p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL); if (p == NULL) return -ENOMEM; p->pdev = pdev; platform_set_drvdata(pdev, p); irq = platform_get_irq(pdev, 0); if (irq < 0) { dev_err(&pdev->dev, "failed to get irq\n"); return -EINVAL; } /* map memory, let base point to the STI instance */ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); p->base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(p->base)) return PTR_ERR(p->base); /* get hold of clock */ p->clk = devm_clk_get(&pdev->dev, "sclk"); if (IS_ERR(p->clk)) { dev_err(&pdev->dev, "cannot get clock\n"); return PTR_ERR(p->clk); } if (devm_request_irq(&pdev->dev, irq, em_sti_interrupt, IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING, dev_name(&pdev->dev), p)) { dev_err(&pdev->dev, "failed to request low IRQ\n"); return -ENOENT; } raw_spin_lock_init(&p->lock); em_sti_register_clockevent(p); em_sti_register_clocksource(p); return 0; } static int em_sti_remove(struct platform_device *pdev) { return -EBUSY; /* cannot unregister clockevent and clocksource */ } static const struct of_device_id em_sti_dt_ids[] = { { .compatible = "renesas,em-sti", }, {}, }; MODULE_DEVICE_TABLE(of, em_sti_dt_ids); static struct platform_driver em_sti_device_driver = { .probe = em_sti_probe, .remove = em_sti_remove, .driver = { .name = "em_sti", .of_match_table = em_sti_dt_ids, } }; static int __init em_sti_init(void) { return platform_driver_register(&em_sti_device_driver); } static void __exit em_sti_exit(void) { platform_driver_unregister(&em_sti_device_driver); } subsys_initcall(em_sti_init); module_exit(em_sti_exit); MODULE_AUTHOR("Magnus Damm"); MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver"); MODULE_LICENSE("GPL v2");