cregit-Linux how code gets into the kernel

Release 4.7 drivers/clocksource/timer-digicolor.c

/*
 * Conexant Digicolor timer driver
 *
 * Author: Baruch Siach <baruch@tkos.co.il>
 *
 * Copyright (C) 2014 Paradox Innovation Ltd.
 *
 * Based on:
 *      Allwinner SoCs hstimer driver
 *
 * Copyright (C) 2013 Maxime Ripard
 *
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

/*
 * Conexant Digicolor SoCs have 8 configurable timers, named from "Timer A" to
 * "Timer H". Timer A is the only one with watchdog support, so it is dedicated
 * to the watchdog driver. This driver uses Timer B for sched_clock(), and
 * Timer C for clockevents.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqreturn.h>
#include <linux/sched_clock.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>

enum {
	
TIMER_A,
	
TIMER_B,
	
TIMER_C,
	
TIMER_D,
	
TIMER_E,
	
TIMER_F,
	
TIMER_G,
	
TIMER_H,
};


#define CONTROL(t)	((t)*8)

#define COUNT(t)	((t)*8 + 4)


#define CONTROL_DISABLE		0

#define CONTROL_ENABLE		BIT(0)

#define CONTROL_MODE(m)		((m) << 4)

#define CONTROL_MODE_ONESHOT	CONTROL_MODE(1)

#define CONTROL_MODE_PERIODIC	CONTROL_MODE(2)


struct digicolor_timer {
	
struct clock_event_device ce;
	
void __iomem *base;
	
u32 ticks_per_jiffy;
	
int timer_id; /* one of TIMER_* */
};


struct digicolor_timer *dc_timer(struct clock_event_device *ce) { return container_of(ce, struct digicolor_timer, ce); }

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static inline void dc_timer_disable(struct clock_event_device *ce) { struct digicolor_timer *dt = dc_timer(ce); writeb(CONTROL_DISABLE, dt->base + CONTROL(dt->timer_id)); }

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static inline void dc_timer_enable(struct clock_event_device *ce, u32 mode) { struct digicolor_timer *dt = dc_timer(ce); writeb(CONTROL_ENABLE | mode, dt->base + CONTROL(dt->timer_id)); }

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static inline void dc_timer_set_count(struct clock_event_device *ce, unsigned long count) { struct digicolor_timer *dt = dc_timer(ce); writel(count, dt->base + COUNT(dt->timer_id)); }

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static int digicolor_clkevt_shutdown(struct clock_event_device *ce) { dc_timer_disable(ce); return 0; }

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static int digicolor_clkevt_set_oneshot(struct clock_event_device *ce) { dc_timer_disable(ce); dc_timer_enable(ce, CONTROL_MODE_ONESHOT); return 0; }

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static int digicolor_clkevt_set_periodic(struct clock_event_device *ce) { struct digicolor_timer *dt = dc_timer(ce); dc_timer_disable(ce); dc_timer_set_count(ce, dt->ticks_per_jiffy); dc_timer_enable(ce, CONTROL_MODE_PERIODIC); return 0; }

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static int digicolor_clkevt_next_event(unsigned long evt, struct clock_event_device *ce) { dc_timer_disable(ce); dc_timer_set_count(ce, evt); dc_timer_enable(ce, CONTROL_MODE_ONESHOT); return 0; }

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static struct digicolor_timer dc_timer_dev = { .ce = { .name = "digicolor_tick", .rating = 340, .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, .set_state_shutdown = digicolor_clkevt_shutdown, .set_state_periodic = digicolor_clkevt_set_periodic, .set_state_oneshot = digicolor_clkevt_set_oneshot, .tick_resume = digicolor_clkevt_shutdown, .set_next_event = digicolor_clkevt_next_event, }, .timer_id = TIMER_C, };
static irqreturn_t digicolor_timer_interrupt(int irq, void *dev_id) { struct clock_event_device *evt = dev_id; evt->event_handler(evt); return IRQ_HANDLED; }

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static u64 notrace digicolor_timer_sched_read(void) { return ~readl(dc_timer_dev.base + COUNT(TIMER_B)); }

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static void __init digicolor_timer_init(struct device_node *node) { unsigned long rate; struct clk *clk; int ret, irq; /* * timer registers are shared with the watchdog timer; * don't map exclusively */ dc_timer_dev.base = of_iomap(node, 0); if (!dc_timer_dev.base) { pr_err("Can't map registers"); return; } irq = irq_of_parse_and_map(node, dc_timer_dev.timer_id); if (irq <= 0) { pr_err("Can't parse IRQ"); return; } clk = of_clk_get(node, 0); if (IS_ERR(clk)) { pr_err("Can't get timer clock"); return; } clk_prepare_enable(clk); rate = clk_get_rate(clk); dc_timer_dev.ticks_per_jiffy = DIV_ROUND_UP(rate, HZ); writeb(CONTROL_DISABLE, dc_timer_dev.base + CONTROL(TIMER_B)); writel(UINT_MAX, dc_timer_dev.base + COUNT(TIMER_B)); writeb(CONTROL_ENABLE, dc_timer_dev.base + CONTROL(TIMER_B)); sched_clock_register(digicolor_timer_sched_read, 32, rate); clocksource_mmio_init(dc_timer_dev.base + COUNT(TIMER_B), node->name, rate, 340, 32, clocksource_mmio_readl_down); ret = request_irq(irq, digicolor_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL, "digicolor_timerC", &dc_timer_dev.ce); if (ret) pr_warn("request of timer irq %d failed (%d)\n", irq, ret); dc_timer_dev.ce.cpumask = cpu_possible_mask; dc_timer_dev.ce.irq = irq; clockevents_config_and_register(&dc_timer_dev.ce, rate, 0, 0xffffffff); }

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CLOCKSOURCE_OF_DECLARE(conexant_digicolor, "cnxt,cx92755-timer", digicolor_timer_init);

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