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72 lines
2.1 KiB
72 lines
2.1 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (C) ST-Ericsson SA 2011 |
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* |
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* Author: Mattias Wallin <[email protected]> for ST-Ericsson |
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* Author: Sundar Iyer for ST-Ericsson |
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* sched_clock implementation is based on: |
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* plat-nomadik/timer.c Linus Walleij <[email protected]> |
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* |
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* DBx500-PRCMU Timer |
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* The PRCMU has 5 timers which are available in a always-on |
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* power domain. We use the Timer 4 for our always-on clock |
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* source on DB8500. |
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*/ |
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#include <linux/of.h> |
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#include <linux/of_address.h> |
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#include <linux/clockchips.h> |
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#define RATE_32K 32768 |
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#define TIMER_MODE_CONTINUOUS 0x1 |
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#define TIMER_DOWNCOUNT_VAL 0xffffffff |
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#define PRCMU_TIMER_REF 0 |
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#define PRCMU_TIMER_DOWNCOUNT 0x4 |
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#define PRCMU_TIMER_MODE 0x8 |
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static void __iomem *clksrc_dbx500_timer_base; |
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static u64 notrace clksrc_dbx500_prcmu_read(struct clocksource *cs) |
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{ |
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void __iomem *base = clksrc_dbx500_timer_base; |
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u32 count, count2; |
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do { |
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count = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT); |
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count2 = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT); |
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} while (count2 != count); |
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/* Negate because the timer is a decrementing counter */ |
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return ~count; |
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} |
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static struct clocksource clocksource_dbx500_prcmu = { |
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.name = "dbx500-prcmu-timer", |
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.rating = 100, |
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.read = clksrc_dbx500_prcmu_read, |
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.mask = CLOCKSOURCE_MASK(32), |
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.flags = CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP, |
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}; |
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static int __init clksrc_dbx500_prcmu_init(struct device_node *node) |
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{ |
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clksrc_dbx500_timer_base = of_iomap(node, 0); |
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/* |
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* The A9 sub system expects the timer to be configured as |
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* a continuous looping timer. |
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* The PRCMU should configure it but if it for some reason |
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* don't we do it here. |
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*/ |
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if (readl(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) != |
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TIMER_MODE_CONTINUOUS) { |
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writel(TIMER_MODE_CONTINUOUS, |
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clksrc_dbx500_timer_base + PRCMU_TIMER_MODE); |
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writel(TIMER_DOWNCOUNT_VAL, |
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clksrc_dbx500_timer_base + PRCMU_TIMER_REF); |
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} |
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return clocksource_register_hz(&clocksource_dbx500_prcmu, RATE_32K); |
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} |
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TIMER_OF_DECLARE(dbx500_prcmu, "stericsson,db8500-prcmu-timer-4", |
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clksrc_dbx500_prcmu_init);
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