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![Daniel Lezcano](/assets/img/avatar_default.png)
The CLOCKSOURCE_OF_DECLARE macro is used widely for the timers to declare the clocksource at early stage. However, this macro is also used to initialize the clockevent if any, or the clockevent only. It was originally suggested to declare another macro to initialize a clockevent, so in order to separate the two entities even they belong to the same IP. This was not accepted because of the impact on the DT where splitting a clocksource/clockevent definition does not make sense as it is a Linux concept not a hardware description. On the other side, the clocksource has not interrupt declared while the clockevent has, so it is easy from the driver to know if the description is for a clockevent or a clocksource, IOW it could be implemented at the driver level. So instead of dealing with a named clocksource macro, let's use a more generic one: TIMER_OF_DECLARE. The patch has not functional changes. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Heiko Stuebner <heiko@sntech.de> Acked-by: Neil Armstrong <narmstrong@baylibre.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Matthias Brugger <matthias.bgg@gmail.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
288 lines
7.5 KiB
C
288 lines
7.5 KiB
C
/*
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* Copyright (C) 2008 STMicroelectronics
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* Copyright (C) 2010 Alessandro Rubini
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* Copyright (C) 2010 Linus Walleij for ST-Ericsson
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2, as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/io.h>
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#include <linux/clockchips.h>
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#include <linux/clocksource.h>
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#include <linux/of_address.h>
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#include <linux/of_irq.h>
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#include <linux/of_platform.h>
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#include <linux/clk.h>
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#include <linux/jiffies.h>
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/sched_clock.h>
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#include <asm/mach/time.h>
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/*
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* The MTU device hosts four different counters, with 4 set of
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* registers. These are register names.
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*/
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#define MTU_IMSC 0x00 /* Interrupt mask set/clear */
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#define MTU_RIS 0x04 /* Raw interrupt status */
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#define MTU_MIS 0x08 /* Masked interrupt status */
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#define MTU_ICR 0x0C /* Interrupt clear register */
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/* per-timer registers take 0..3 as argument */
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#define MTU_LR(x) (0x10 + 0x10 * (x) + 0x00) /* Load value */
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#define MTU_VAL(x) (0x10 + 0x10 * (x) + 0x04) /* Current value */
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#define MTU_CR(x) (0x10 + 0x10 * (x) + 0x08) /* Control reg */
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#define MTU_BGLR(x) (0x10 + 0x10 * (x) + 0x0c) /* At next overflow */
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/* bits for the control register */
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#define MTU_CRn_ENA 0x80
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#define MTU_CRn_PERIODIC 0x40 /* if 0 = free-running */
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#define MTU_CRn_PRESCALE_MASK 0x0c
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#define MTU_CRn_PRESCALE_1 0x00
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#define MTU_CRn_PRESCALE_16 0x04
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#define MTU_CRn_PRESCALE_256 0x08
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#define MTU_CRn_32BITS 0x02
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#define MTU_CRn_ONESHOT 0x01 /* if 0 = wraps reloading from BGLR*/
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/* Other registers are usual amba/primecell registers, currently not used */
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#define MTU_ITCR 0xff0
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#define MTU_ITOP 0xff4
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#define MTU_PERIPH_ID0 0xfe0
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#define MTU_PERIPH_ID1 0xfe4
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#define MTU_PERIPH_ID2 0xfe8
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#define MTU_PERIPH_ID3 0xfeC
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#define MTU_PCELL0 0xff0
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#define MTU_PCELL1 0xff4
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#define MTU_PCELL2 0xff8
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#define MTU_PCELL3 0xffC
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static void __iomem *mtu_base;
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static bool clkevt_periodic;
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static u32 clk_prescale;
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static u32 nmdk_cycle; /* write-once */
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static struct delay_timer mtu_delay_timer;
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#ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
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/*
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* Override the global weak sched_clock symbol with this
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* local implementation which uses the clocksource to get some
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* better resolution when scheduling the kernel.
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*/
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static u64 notrace nomadik_read_sched_clock(void)
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{
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if (unlikely(!mtu_base))
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return 0;
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return -readl(mtu_base + MTU_VAL(0));
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}
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#endif
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static unsigned long nmdk_timer_read_current_timer(void)
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{
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return ~readl_relaxed(mtu_base + MTU_VAL(0));
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}
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/* Clockevent device: use one-shot mode */
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static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev)
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{
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writel(1 << 1, mtu_base + MTU_IMSC);
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writel(evt, mtu_base + MTU_LR(1));
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/* Load highest value, enable device, enable interrupts */
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writel(MTU_CRn_ONESHOT | clk_prescale |
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MTU_CRn_32BITS | MTU_CRn_ENA,
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mtu_base + MTU_CR(1));
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return 0;
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}
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static void nmdk_clkevt_reset(void)
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{
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if (clkevt_periodic) {
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/* Timer: configure load and background-load, and fire it up */
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writel(nmdk_cycle, mtu_base + MTU_LR(1));
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writel(nmdk_cycle, mtu_base + MTU_BGLR(1));
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writel(MTU_CRn_PERIODIC | clk_prescale |
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MTU_CRn_32BITS | MTU_CRn_ENA,
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mtu_base + MTU_CR(1));
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writel(1 << 1, mtu_base + MTU_IMSC);
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} else {
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/* Generate an interrupt to start the clockevent again */
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(void) nmdk_clkevt_next(nmdk_cycle, NULL);
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}
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}
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static int nmdk_clkevt_shutdown(struct clock_event_device *evt)
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{
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writel(0, mtu_base + MTU_IMSC);
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/* disable timer */
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writel(0, mtu_base + MTU_CR(1));
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/* load some high default value */
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writel(0xffffffff, mtu_base + MTU_LR(1));
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return 0;
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}
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static int nmdk_clkevt_set_oneshot(struct clock_event_device *evt)
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{
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clkevt_periodic = false;
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return 0;
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}
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static int nmdk_clkevt_set_periodic(struct clock_event_device *evt)
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{
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clkevt_periodic = true;
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nmdk_clkevt_reset();
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return 0;
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}
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static void nmdk_clksrc_reset(void)
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{
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/* Disable */
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writel(0, mtu_base + MTU_CR(0));
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/* ClockSource: configure load and background-load, and fire it up */
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writel(nmdk_cycle, mtu_base + MTU_LR(0));
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writel(nmdk_cycle, mtu_base + MTU_BGLR(0));
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writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA,
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mtu_base + MTU_CR(0));
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}
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static void nmdk_clkevt_resume(struct clock_event_device *cedev)
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{
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nmdk_clkevt_reset();
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nmdk_clksrc_reset();
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}
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static struct clock_event_device nmdk_clkevt = {
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.name = "mtu_1",
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.features = CLOCK_EVT_FEAT_ONESHOT |
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CLOCK_EVT_FEAT_PERIODIC |
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CLOCK_EVT_FEAT_DYNIRQ,
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.rating = 200,
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.set_state_shutdown = nmdk_clkevt_shutdown,
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.set_state_periodic = nmdk_clkevt_set_periodic,
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.set_state_oneshot = nmdk_clkevt_set_oneshot,
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.set_next_event = nmdk_clkevt_next,
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.resume = nmdk_clkevt_resume,
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};
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/*
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* IRQ Handler for timer 1 of the MTU block.
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*/
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static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id)
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{
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struct clock_event_device *evdev = dev_id;
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writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */
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evdev->event_handler(evdev);
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return IRQ_HANDLED;
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}
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static struct irqaction nmdk_timer_irq = {
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.name = "Nomadik Timer Tick",
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.flags = IRQF_TIMER,
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.handler = nmdk_timer_interrupt,
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.dev_id = &nmdk_clkevt,
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};
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static int __init nmdk_timer_init(void __iomem *base, int irq,
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struct clk *pclk, struct clk *clk)
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{
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unsigned long rate;
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int ret;
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mtu_base = base;
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BUG_ON(clk_prepare_enable(pclk));
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BUG_ON(clk_prepare_enable(clk));
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/*
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* Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz
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* for ux500.
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* Use a divide-by-16 counter if the tick rate is more than 32MHz.
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* At 32 MHz, the timer (with 32 bit counter) can be programmed
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* to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer
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* with 16 gives too low timer resolution.
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*/
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rate = clk_get_rate(clk);
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if (rate > 32000000) {
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rate /= 16;
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clk_prescale = MTU_CRn_PRESCALE_16;
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} else {
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clk_prescale = MTU_CRn_PRESCALE_1;
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}
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/* Cycles for periodic mode */
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nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ);
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/* Timer 0 is the free running clocksource */
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nmdk_clksrc_reset();
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ret = clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0",
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rate, 200, 32, clocksource_mmio_readl_down);
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if (ret) {
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pr_err("timer: failed to initialize clock source %s\n", "mtu_0");
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return ret;
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}
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#ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK
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sched_clock_register(nomadik_read_sched_clock, 32, rate);
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#endif
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/* Timer 1 is used for events, register irq and clockevents */
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setup_irq(irq, &nmdk_timer_irq);
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nmdk_clkevt.cpumask = cpumask_of(0);
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nmdk_clkevt.irq = irq;
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clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU);
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mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer;
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mtu_delay_timer.freq = rate;
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register_current_timer_delay(&mtu_delay_timer);
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return 0;
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}
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static int __init nmdk_timer_of_init(struct device_node *node)
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{
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struct clk *pclk;
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struct clk *clk;
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void __iomem *base;
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int irq;
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base = of_iomap(node, 0);
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if (!base) {
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pr_err("Can't remap registers\n");
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return -ENXIO;
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}
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pclk = of_clk_get_by_name(node, "apb_pclk");
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if (IS_ERR(pclk)) {
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pr_err("could not get apb_pclk\n");
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return PTR_ERR(pclk);
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}
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clk = of_clk_get_by_name(node, "timclk");
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if (IS_ERR(clk)) {
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pr_err("could not get timclk\n");
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return PTR_ERR(clk);
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}
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irq = irq_of_parse_and_map(node, 0);
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if (irq <= 0) {
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pr_err("Can't parse IRQ\n");
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return -EINVAL;
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}
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return nmdk_timer_init(base, irq, pclk, clk);
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}
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TIMER_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu",
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nmdk_timer_of_init);
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