remarkable-linux/drivers/clocksource/timer-nps.c

/*
 * Copyright (c) 2016, Mellanox Technologies. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/interrupt.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/cpu.h>
#include <soc/nps/common.h>

#define NPS_MSU_TICK_LOW	0xC8
#define NPS_CLUSTER_OFFSET	8
#define NPS_CLUSTER_NUM		16

/* This array is per cluster of CPUs (Each NPS400 cluster got 256 CPUs) */
static void *nps_msu_reg_low_addr[NPS_CLUSTER_NUM] __read_mostly;

static int __init nps_get_timer_clk(struct device_node *node,
			     unsigned long *timer_freq,
			     struct clk **clk)
{
	int ret;

	*clk = of_clk_get(node, 0);
	ret = PTR_ERR_OR_ZERO(*clk);
	if (ret) {
		pr_err("timer missing clk\n");
		return ret;
	}

	ret = clk_prepare_enable(*clk);
	if (ret) {
		pr_err("Couldn't enable parent clk\n");
		clk_put(*clk);
		return ret;
	}

	*timer_freq = clk_get_rate(*clk);
	if (!(*timer_freq)) {
		pr_err("Couldn't get clk rate\n");
		clk_disable_unprepare(*clk);
		clk_put(*clk);
		return -EINVAL;
	}

	return 0;
}

static u64 nps_clksrc_read(struct clocksource *clksrc)
{
	int cluster = raw_smp_processor_id() >> NPS_CLUSTER_OFFSET;

	return (u64)ioread32be(nps_msu_reg_low_addr[cluster]);
}

static int __init nps_setup_clocksource(struct device_node *node)
{
	int ret, cluster;
	struct clk *clk;
	unsigned long nps_timer1_freq;


	for (cluster = 0; cluster < NPS_CLUSTER_NUM; cluster++)
		nps_msu_reg_low_addr[cluster] =
			nps_host_reg((cluster << NPS_CLUSTER_OFFSET),
				     NPS_MSU_BLKID, NPS_MSU_TICK_LOW);

	ret = nps_get_timer_clk(node, &nps_timer1_freq, &clk);
	if (ret)
		return ret;

	ret = clocksource_mmio_init(nps_msu_reg_low_addr, "nps-tick",
				    nps_timer1_freq, 300, 32, nps_clksrc_read);
	if (ret) {
		pr_err("Couldn't register clock source.\n");
		clk_disable_unprepare(clk);
	}

	return ret;
}

TIMER_OF_DECLARE(ezchip_nps400_clksrc, "ezchip,nps400-timer",
		       nps_setup_clocksource);
TIMER_OF_DECLARE(ezchip_nps400_clk_src, "ezchip,nps400-timer1",
		       nps_setup_clocksource);

#ifdef CONFIG_EZNPS_MTM_EXT
#include <soc/nps/mtm.h>

/* Timer related Aux registers */
#define NPS_REG_TIMER0_TSI	0xFFFFF850
#define NPS_REG_TIMER0_LIMIT	0x23
#define NPS_REG_TIMER0_CTRL	0x22
#define NPS_REG_TIMER0_CNT	0x21

/*
 * Interrupt Enabled (IE) - re-arm the timer
 * Not Halted (NH) - is cleared when working with JTAG (for debug)
 */
#define TIMER0_CTRL_IE		BIT(0)
#define TIMER0_CTRL_NH		BIT(1)

static unsigned long nps_timer0_freq;
static unsigned long nps_timer0_irq;

static void nps_clkevent_rm_thread(void)
{
	int thread;
	unsigned int cflags, enabled_threads;

	hw_schd_save(&cflags);

	enabled_threads = read_aux_reg(NPS_REG_TIMER0_TSI);

	/* remove thread from TSI1 */
	thread = read_aux_reg(CTOP_AUX_THREAD_ID);
	enabled_threads &= ~(1 << thread);
	write_aux_reg(NPS_REG_TIMER0_TSI, enabled_threads);

	/* Acknowledge and if needed re-arm the timer */
	if (!enabled_threads)
		write_aux_reg(NPS_REG_TIMER0_CTRL, TIMER0_CTRL_NH);
	else
		write_aux_reg(NPS_REG_TIMER0_CTRL,
			      TIMER0_CTRL_IE | TIMER0_CTRL_NH);

	hw_schd_restore(cflags);
}

static void nps_clkevent_add_thread(unsigned long delta)
{
	int thread;
	unsigned int cflags, enabled_threads;

	hw_schd_save(&cflags);

	/* add thread to TSI1 */
	thread = read_aux_reg(CTOP_AUX_THREAD_ID);
	enabled_threads = read_aux_reg(NPS_REG_TIMER0_TSI);
	enabled_threads |= (1 << thread);
	write_aux_reg(NPS_REG_TIMER0_TSI, enabled_threads);

	/* set next timer event */
	write_aux_reg(NPS_REG_TIMER0_LIMIT, delta);
	write_aux_reg(NPS_REG_TIMER0_CNT, 0);
	write_aux_reg(NPS_REG_TIMER0_CTRL,
		      TIMER0_CTRL_IE | TIMER0_CTRL_NH);

	hw_schd_restore(cflags);
}

/*
 * Whenever anyone tries to change modes, we just mask interrupts
 * and wait for the next event to get set.
 */
static int nps_clkevent_set_state(struct clock_event_device *dev)
{
	nps_clkevent_rm_thread();
	disable_percpu_irq(nps_timer0_irq);

	return 0;
}

static int nps_clkevent_set_next_event(unsigned long delta,
				       struct clock_event_device *dev)
{
	nps_clkevent_add_thread(delta);
	enable_percpu_irq(nps_timer0_irq, IRQ_TYPE_NONE);

	return 0;
}

static DEFINE_PER_CPU(struct clock_event_device, nps_clockevent_device) = {
	.name				=	"NPS Timer0",
	.features			=	CLOCK_EVT_FEAT_ONESHOT,
	.rating				=	300,
	.set_next_event			=	nps_clkevent_set_next_event,
	.set_state_oneshot		=	nps_clkevent_set_state,
	.set_state_oneshot_stopped	=	nps_clkevent_set_state,
	.set_state_shutdown		=	nps_clkevent_set_state,
	.tick_resume			=	nps_clkevent_set_state,
};

static irqreturn_t timer_irq_handler(int irq, void *dev_id)
{
	struct clock_event_device *evt = dev_id;

	nps_clkevent_rm_thread();
	evt->event_handler(evt);

	return IRQ_HANDLED;
}

static int nps_timer_starting_cpu(unsigned int cpu)
{
	struct clock_event_device *evt = this_cpu_ptr(&nps_clockevent_device);

	evt->cpumask = cpumask_of(smp_processor_id());

	clockevents_config_and_register(evt, nps_timer0_freq, 0, ULONG_MAX);
	enable_percpu_irq(nps_timer0_irq, IRQ_TYPE_NONE);

	return 0;
}

static int nps_timer_dying_cpu(unsigned int cpu)
{
	disable_percpu_irq(nps_timer0_irq);
	return 0;
}

static int __init nps_setup_clockevent(struct device_node *node)
{
	struct clk *clk;
	int ret;

	nps_timer0_irq = irq_of_parse_and_map(node, 0);
	if (nps_timer0_irq <= 0) {
		pr_err("clockevent: missing irq\n");
		return -EINVAL;
	}

	ret = nps_get_timer_clk(node, &nps_timer0_freq, &clk);
	if (ret)
		return ret;

	/* Needs apriori irq_set_percpu_devid() done in intc map function */
	ret = request_percpu_irq(nps_timer0_irq, timer_irq_handler,
				 "Timer0 (per-cpu-tick)",
				 &nps_clockevent_device);
	if (ret) {
		pr_err("Couldn't request irq\n");
		clk_disable_unprepare(clk);
		return ret;
	}

	ret = cpuhp_setup_state(CPUHP_AP_ARC_TIMER_STARTING,
				"clockevents/nps:starting",
				nps_timer_starting_cpu,
				nps_timer_dying_cpu);
	if (ret) {
		pr_err("Failed to setup hotplug state\n");
		clk_disable_unprepare(clk);
		free_percpu_irq(nps_timer0_irq, &nps_clockevent_device);
		return ret;
	}

	return 0;
}

TIMER_OF_DECLARE(ezchip_nps400_clk_evt, "ezchip,nps400-timer0",
		       nps_setup_clockevent);
#endif /* CONFIG_EZNPS_MTM_EXT */