clocksource: Add NPS400 timers driver

NPS Network Processor

Required properties:

- compatible :	should be "ezchip,nps400-timer"

Clocks required for compatible = "ezchip,nps400-timer":

- clocks : Must contain a single entry describing the clock input

Example:

timer {

	compatible = "ezchip,nps400-timer";

	clocks = <&sysclk>;

};

	  This option enables support for Texas Instruments 32.768 Hz clocksource

	  available on many OMAP-like platforms.

config CLKSRC_NPS

	bool "NPS400 clocksource driver" if COMPILE_TEST

	depends on !PHYS_ADDR_T_64BIT

	select CLKSRC_MMIO

	select CLKSRC_OF if OF

	help

	  NPS400 clocksource support.

	  Got 64 bit counter with update rate up to 1000MHz.

	  This counter is accessed via couple of 32 bit memory mapped registers.

config CLKSRC_STM32

	bool "Clocksource for STM32 SoCs" if !ARCH_STM32

	depends on OF && ARM && (ARCH_STM32 || COMPILE_TEST)

obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o

obj-$(CONFIG_CLKSRC_PISTACHIO)	+= time-pistachio.o

obj-$(CONFIG_CLKSRC_TI_32K)	+= timer-ti-32k.o

obj-$(CONFIG_CLKSRC_NPS)	+= timer-nps.o

obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer.o

obj-$(CONFIG_ARM_GLOBAL_TIMER)		+= arm_global_timer.o

/*

 * 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

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 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

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 */

#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 unsigned long nps_timer_rate;

static cycle_t nps_clksrc_read(struct clocksource *clksrc)

{

	int cluster = raw_smp_processor_id() >> NPS_CLUSTER_OFFSET;

	return (cycle_t)ioread32be(nps_msu_reg_low_addr[cluster]);

}

static void __init nps_setup_clocksource(struct device_node *node,

					 struct clk *clk)

{

	int ret, cluster;

	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 = clk_prepare_enable(clk);

	if (ret) {

		pr_err("Couldn't enable parent clock\n");

		return;

	}

	nps_timer_rate = clk_get_rate(clk);

	ret = clocksource_mmio_init(nps_msu_reg_low_addr, "EZnps-tick",

				    nps_timer_rate, 301, 32, nps_clksrc_read);

	if (ret) {

		pr_err("Couldn't register clock source.\n");

		clk_disable_unprepare(clk);

	}

}

static void __init nps_timer_init(struct device_node *node)

{

	struct clk *clk;

	clk = of_clk_get(node, 0);

	if (IS_ERR(clk)) {

		pr_err("Can't get timer clock.\n");

		return;

	}

	nps_setup_clocksource(node, clk);

}

CLOCKSOURCE_OF_DECLARE(ezchip_nps400_clksrc, "ezchip,nps400-timer",

		       nps_timer_init);