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371 lines
8.4 KiB
371 lines
8.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Emma Mobile Timer Support - STI |
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* |
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* Copyright (C) 2012 Magnus Damm |
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*/ |
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#include <linux/init.h> |
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#include <linux/platform_device.h> |
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#include <linux/spinlock.h> |
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#include <linux/interrupt.h> |
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#include <linux/ioport.h> |
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#include <linux/io.h> |
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#include <linux/clk.h> |
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#include <linux/irq.h> |
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#include <linux/err.h> |
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#include <linux/delay.h> |
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#include <linux/clocksource.h> |
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#include <linux/clockchips.h> |
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#include <linux/slab.h> |
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#include <linux/module.h> |
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enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR }; |
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struct em_sti_priv { |
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void __iomem *base; |
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struct clk *clk; |
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struct platform_device *pdev; |
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unsigned int active[USER_NR]; |
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unsigned long rate; |
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raw_spinlock_t lock; |
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struct clock_event_device ced; |
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struct clocksource cs; |
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}; |
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#define STI_CONTROL 0x00 |
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#define STI_COMPA_H 0x10 |
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#define STI_COMPA_L 0x14 |
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#define STI_COMPB_H 0x18 |
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#define STI_COMPB_L 0x1c |
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#define STI_COUNT_H 0x20 |
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#define STI_COUNT_L 0x24 |
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#define STI_COUNT_RAW_H 0x28 |
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#define STI_COUNT_RAW_L 0x2c |
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#define STI_SET_H 0x30 |
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#define STI_SET_L 0x34 |
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#define STI_INTSTATUS 0x40 |
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#define STI_INTRAWSTATUS 0x44 |
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#define STI_INTENSET 0x48 |
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#define STI_INTENCLR 0x4c |
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#define STI_INTFFCLR 0x50 |
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static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs) |
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{ |
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return ioread32(p->base + offs); |
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} |
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static inline void em_sti_write(struct em_sti_priv *p, int offs, |
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unsigned long value) |
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{ |
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iowrite32(value, p->base + offs); |
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} |
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static int em_sti_enable(struct em_sti_priv *p) |
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{ |
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int ret; |
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/* enable clock */ |
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ret = clk_enable(p->clk); |
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if (ret) { |
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dev_err(&p->pdev->dev, "cannot enable clock\n"); |
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return ret; |
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} |
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/* reset the counter */ |
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em_sti_write(p, STI_SET_H, 0x40000000); |
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em_sti_write(p, STI_SET_L, 0x00000000); |
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/* mask and clear pending interrupts */ |
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em_sti_write(p, STI_INTENCLR, 3); |
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em_sti_write(p, STI_INTFFCLR, 3); |
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/* enable updates of counter registers */ |
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em_sti_write(p, STI_CONTROL, 1); |
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return 0; |
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} |
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static void em_sti_disable(struct em_sti_priv *p) |
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{ |
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/* mask interrupts */ |
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em_sti_write(p, STI_INTENCLR, 3); |
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/* stop clock */ |
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clk_disable(p->clk); |
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} |
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static u64 em_sti_count(struct em_sti_priv *p) |
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{ |
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u64 ticks; |
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unsigned long flags; |
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/* the STI hardware buffers the 48-bit count, but to |
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* break it out into two 32-bit access the registers |
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* must be accessed in a certain order. |
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* Always read STI_COUNT_H before STI_COUNT_L. |
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*/ |
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raw_spin_lock_irqsave(&p->lock, flags); |
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ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32; |
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ticks |= em_sti_read(p, STI_COUNT_L); |
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raw_spin_unlock_irqrestore(&p->lock, flags); |
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return ticks; |
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} |
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static u64 em_sti_set_next(struct em_sti_priv *p, u64 next) |
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{ |
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unsigned long flags; |
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raw_spin_lock_irqsave(&p->lock, flags); |
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/* mask compare A interrupt */ |
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em_sti_write(p, STI_INTENCLR, 1); |
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/* update compare A value */ |
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em_sti_write(p, STI_COMPA_H, next >> 32); |
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em_sti_write(p, STI_COMPA_L, next & 0xffffffff); |
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/* clear compare A interrupt source */ |
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em_sti_write(p, STI_INTFFCLR, 1); |
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/* unmask compare A interrupt */ |
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em_sti_write(p, STI_INTENSET, 1); |
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raw_spin_unlock_irqrestore(&p->lock, flags); |
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return next; |
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} |
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static irqreturn_t em_sti_interrupt(int irq, void *dev_id) |
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{ |
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struct em_sti_priv *p = dev_id; |
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p->ced.event_handler(&p->ced); |
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return IRQ_HANDLED; |
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} |
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static int em_sti_start(struct em_sti_priv *p, unsigned int user) |
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{ |
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unsigned long flags; |
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int used_before; |
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int ret = 0; |
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raw_spin_lock_irqsave(&p->lock, flags); |
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used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; |
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if (!used_before) |
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ret = em_sti_enable(p); |
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if (!ret) |
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p->active[user] = 1; |
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raw_spin_unlock_irqrestore(&p->lock, flags); |
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return ret; |
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} |
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static void em_sti_stop(struct em_sti_priv *p, unsigned int user) |
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{ |
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unsigned long flags; |
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int used_before, used_after; |
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raw_spin_lock_irqsave(&p->lock, flags); |
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used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; |
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p->active[user] = 0; |
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used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT]; |
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if (used_before && !used_after) |
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em_sti_disable(p); |
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raw_spin_unlock_irqrestore(&p->lock, flags); |
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} |
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static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs) |
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{ |
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return container_of(cs, struct em_sti_priv, cs); |
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} |
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static u64 em_sti_clocksource_read(struct clocksource *cs) |
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{ |
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return em_sti_count(cs_to_em_sti(cs)); |
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} |
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static int em_sti_clocksource_enable(struct clocksource *cs) |
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{ |
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struct em_sti_priv *p = cs_to_em_sti(cs); |
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return em_sti_start(p, USER_CLOCKSOURCE); |
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} |
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static void em_sti_clocksource_disable(struct clocksource *cs) |
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{ |
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em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE); |
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} |
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static void em_sti_clocksource_resume(struct clocksource *cs) |
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{ |
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em_sti_clocksource_enable(cs); |
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} |
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static int em_sti_register_clocksource(struct em_sti_priv *p) |
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{ |
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struct clocksource *cs = &p->cs; |
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cs->name = dev_name(&p->pdev->dev); |
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cs->rating = 200; |
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cs->read = em_sti_clocksource_read; |
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cs->enable = em_sti_clocksource_enable; |
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cs->disable = em_sti_clocksource_disable; |
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cs->suspend = em_sti_clocksource_disable; |
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cs->resume = em_sti_clocksource_resume; |
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cs->mask = CLOCKSOURCE_MASK(48); |
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cs->flags = CLOCK_SOURCE_IS_CONTINUOUS; |
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dev_info(&p->pdev->dev, "used as clock source\n"); |
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clocksource_register_hz(cs, p->rate); |
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return 0; |
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} |
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static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced) |
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{ |
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return container_of(ced, struct em_sti_priv, ced); |
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} |
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static int em_sti_clock_event_shutdown(struct clock_event_device *ced) |
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{ |
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struct em_sti_priv *p = ced_to_em_sti(ced); |
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em_sti_stop(p, USER_CLOCKEVENT); |
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return 0; |
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} |
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static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced) |
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{ |
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struct em_sti_priv *p = ced_to_em_sti(ced); |
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dev_info(&p->pdev->dev, "used for oneshot clock events\n"); |
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em_sti_start(p, USER_CLOCKEVENT); |
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return 0; |
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} |
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static int em_sti_clock_event_next(unsigned long delta, |
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struct clock_event_device *ced) |
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{ |
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struct em_sti_priv *p = ced_to_em_sti(ced); |
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u64 next; |
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int safe; |
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next = em_sti_set_next(p, em_sti_count(p) + delta); |
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safe = em_sti_count(p) < (next - 1); |
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return !safe; |
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} |
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static void em_sti_register_clockevent(struct em_sti_priv *p) |
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{ |
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struct clock_event_device *ced = &p->ced; |
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ced->name = dev_name(&p->pdev->dev); |
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ced->features = CLOCK_EVT_FEAT_ONESHOT; |
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ced->rating = 200; |
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ced->cpumask = cpu_possible_mask; |
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ced->set_next_event = em_sti_clock_event_next; |
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ced->set_state_shutdown = em_sti_clock_event_shutdown; |
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ced->set_state_oneshot = em_sti_clock_event_set_oneshot; |
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dev_info(&p->pdev->dev, "used for clock events\n"); |
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clockevents_config_and_register(ced, p->rate, 2, 0xffffffff); |
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} |
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static int em_sti_probe(struct platform_device *pdev) |
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{ |
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struct em_sti_priv *p; |
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int irq, ret; |
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p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL); |
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if (p == NULL) |
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return -ENOMEM; |
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p->pdev = pdev; |
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platform_set_drvdata(pdev, p); |
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irq = platform_get_irq(pdev, 0); |
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if (irq < 0) |
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return irq; |
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/* map memory, let base point to the STI instance */ |
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p->base = devm_platform_ioremap_resource(pdev, 0); |
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if (IS_ERR(p->base)) |
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return PTR_ERR(p->base); |
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ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt, |
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IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING, |
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dev_name(&pdev->dev), p); |
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if (ret) { |
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dev_err(&pdev->dev, "failed to request low IRQ\n"); |
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return ret; |
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} |
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/* get hold of clock */ |
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p->clk = devm_clk_get(&pdev->dev, "sclk"); |
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if (IS_ERR(p->clk)) { |
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dev_err(&pdev->dev, "cannot get clock\n"); |
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return PTR_ERR(p->clk); |
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} |
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ret = clk_prepare(p->clk); |
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if (ret < 0) { |
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dev_err(&pdev->dev, "cannot prepare clock\n"); |
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return ret; |
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} |
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ret = clk_enable(p->clk); |
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if (ret < 0) { |
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dev_err(&p->pdev->dev, "cannot enable clock\n"); |
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clk_unprepare(p->clk); |
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return ret; |
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} |
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p->rate = clk_get_rate(p->clk); |
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clk_disable(p->clk); |
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raw_spin_lock_init(&p->lock); |
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em_sti_register_clockevent(p); |
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em_sti_register_clocksource(p); |
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return 0; |
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} |
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static int em_sti_remove(struct platform_device *pdev) |
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{ |
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return -EBUSY; /* cannot unregister clockevent and clocksource */ |
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} |
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static const struct of_device_id em_sti_dt_ids[] = { |
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{ .compatible = "renesas,em-sti", }, |
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{}, |
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}; |
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MODULE_DEVICE_TABLE(of, em_sti_dt_ids); |
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static struct platform_driver em_sti_device_driver = { |
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.probe = em_sti_probe, |
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.remove = em_sti_remove, |
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.driver = { |
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.name = "em_sti", |
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.of_match_table = em_sti_dt_ids, |
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} |
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}; |
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static int __init em_sti_init(void) |
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{ |
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return platform_driver_register(&em_sti_device_driver); |
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} |
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static void __exit em_sti_exit(void) |
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{ |
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platform_driver_unregister(&em_sti_device_driver); |
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} |
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subsys_initcall(em_sti_init); |
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module_exit(em_sti_exit); |
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MODULE_AUTHOR("Magnus Damm"); |
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MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver"); |
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MODULE_LICENSE("GPL v2");
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