text: /*
   * Copyright (C) 2005-2013 Imagination Technologies Ltd.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *
   * Support for Meta per-thread timers.
   *
   * Meta hardware threads have 2 timers. The background timer (TXTIMER) is used
   * as a free-running time base (hz clocksource), and the interrupt timer
   * (TXTIMERI) is used for the timer interrupt (clock event). Both counters
   * traditionally count at approximately 1MHz.
   */
  
  #include <clocksource/metag_generic.h>
  #include <linux/cpu.h>
  #include <linux/errno.h>
  #include <linux/sched.h>
  #include <linux/kernel.h>
  #include <linux/param.h>
  #include <linux/time.h>
  #include <linux/init.h>
  #include <linux/proc_fs.h>
  #include <linux/clocksource.h>
  #include <linux/clockchips.h>
  #include <linux/interrupt.h>
  
  #include <asm/clock.h>
  #include <asm/hwthread.h>
  #include <asm/core_reg.h>
  #include <asm/metag_mem.h>
  #include <asm/tbx.h>
  
  #define HARDWARE_FREQ		1000000	/* 1MHz */
  #define HARDWARE_DIV		1	/* divide by 1 = 1MHz clock */
  #define HARDWARE_TO_NS_SHIFT	10	/* convert ticks to ns */
  
  static unsigned int hwtimer_freq = HARDWARE_FREQ;
  static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
  static DEFINE_PER_CPU(char [11], local_clockevent_name);
  
  static int metag_timer_set_next_event(unsigned long delta,
  				      struct clock_event_device *dev)
  {
  	__core_reg_set(TXTIMERI, -delta);
  	return 0;
  }
  
  static cycle_t metag_clocksource_read(struct clocksource *cs)
  {
  	return __core_reg_get(TXTIMER);
  }
  
  static struct clocksource clocksource_metag = {
  	.name = "META",
  	.rating = 200,
  	.mask = CLOCKSOURCE_MASK(32),
  	.read = metag_clocksource_read,
  	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
  };
  
  static irqreturn_t metag_timer_interrupt(int irq, void *dummy)
  {
  	struct clock_event_device *evt = this_cpu_ptr(&local_clockevent);
  
  	evt->event_handler(evt);
  
  	return IRQ_HANDLED;
  }
  
  static struct irqaction metag_timer_irq = {
  	.name = "META core timer",
  	.handler = metag_timer_interrupt,
  	.flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_PERCPU,
  };
  
  unsigned long long sched_clock(void)
  {
  	unsigned long long ticks = __core_reg_get(TXTIMER);
  	return ticks << HARDWARE_TO_NS_SHIFT;
  }
  
  static int arch_timer_starting_cpu(unsigned int cpu)
  {
  	unsigned int txdivtime;
  	struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
  	char *name = per_cpu(local_clockevent_name, cpu);
  
  	txdivtime = __core_reg_get(TXDIVTIME);
  
  	txdivtime &= ~TXDIVTIME_DIV_BITS;
  	txdivtime |= (HARDWARE_DIV & TXDIVTIME_DIV_BITS);
  
  	__core_reg_set(TXDIVTIME, txdivtime);
  
  	sprintf(name, "META %d", cpu);
  	clk->name = name;
  	clk->features = CLOCK_EVT_FEAT_ONESHOT,
  
  	clk->rating = 200,
  	clk->shift = 12,
  	clk->irq = tbisig_map(TBID_SIGNUM_TRT),
  	clk->set_next_event = metag_timer_set_next_event,
  
  	clk->mult = div_sc(hwtimer_freq, NSEC_PER_SEC, clk->shift);
  	clk->max_delta_ns = clockevent_delta2ns(0x7fffffff, clk);
  	clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
  	clk->cpumask = cpumask_of(cpu);
  
  	clockevents_register_device(clk);
  
  	/*
  	 * For all non-boot CPUs we need to synchronize our free
  	 * running clock (TXTIMER) with the boot CPU's clock.
  	 *
  	 * While this won't be accurate, it should be close enough.
  	 */
  	if (cpu) {
  		unsigned int thread0 = cpu_2_hwthread_id[0];
  		unsigned long val;
  
  		val = core_reg_read(TXUCT_ID, TXTIMER_REGNUM, thread0);
  		__core_reg_set(TXTIMER, val);
  	}
  	return 0;
  }
  
  int __init metag_generic_timer_init(void)
  {
  	/*
  	 * On Meta 2 SoCs, the actual frequency of the timer is based on the
  	 * Meta core clock speed divided by an integer, so it is only
  	 * approximately 1MHz. Calculating the real frequency here drastically
  	 * reduces clock skew on these SoCs.
  	 */
  #ifdef CONFIG_METAG_META21
  	hwtimer_freq = get_coreclock() / (metag_in32(EXPAND_TIMER_DIV) + 1);
  #endif
  	pr_info("Timer frequency: %u Hz\n", hwtimer_freq);
  
  	clocksource_register_hz(&clocksource_metag, hwtimer_freq);
  
  	setup_irq(tbisig_map(TBID_SIGNUM_TRT), &metag_timer_irq);
  
  	/* Hook cpu boot to configure the CPU's timers */
  	return cpuhp_setup_state(CPUHP_AP_METAG_TIMER_STARTING,
  				 "AP_METAG_TIMER_STARTING",
  				 arch_timer_starting_cpu, NULL);
  }
  