text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * Copyright (C) 2014, STMicroelectronics - All Rights Reserved
   * Author(s): Vikas Manocha, <vikas.manocha@st.com> for STMicroelectronics.
   */
  
  #include <common.h>
  #include <asm/io.h>
  #include <asm/arch-stv0991/hardware.h>
  #include <asm/arch-stv0991/stv0991_cgu.h>
  #include <asm/arch-stv0991/stv0991_gpt.h>
  
  static struct stv0991_cgu_regs *const stv0991_cgu_regs = \
  				(struct stv0991_cgu_regs *) (CGU_BASE_ADDR);
  
  #define READ_TIMER()	(readl(&gpt1_regs_ptr->cnt) & GPT_FREE_RUNNING)
  #define GPT_RESOLUTION	(CONFIG_STV0991_HZ_CLOCK / CONFIG_STV0991_HZ)
  
  DECLARE_GLOBAL_DATA_PTR;
  
  #define timestamp gd->arch.tbl
  #define lastdec gd->arch.lastinc
  
  static ulong get_timer_masked(void);
  
  int timer_init(void)
  {
  	/* Timer1 clock configuration */
  	writel(TIMER1_CLK_CFG, &stv0991_cgu_regs->tim_freq);
  	writel(readl(&stv0991_cgu_regs->cgu_enable_2) |
  			TIMER1_CLK_EN, &stv0991_cgu_regs->cgu_enable_2);
  
  	/* Stop the timer */
  	writel(readl(&gpt1_regs_ptr->cr1) & ~GPT_CR1_CEN, &gpt1_regs_ptr->cr1);
  	writel(GPT_PRESCALER_128, &gpt1_regs_ptr->psc);
  	/* Configure timer for auto-reload */
  	writel(readl(&gpt1_regs_ptr->cr1) | GPT_MODE_AUTO_RELOAD,
  			&gpt1_regs_ptr->cr1);
  
  	/* load value for free running */
  	writel(GPT_FREE_RUNNING, &gpt1_regs_ptr->arr);
  
  	/* start timer */
  	writel(readl(&gpt1_regs_ptr->cr1) | GPT_CR1_CEN,
  			&gpt1_regs_ptr->cr1);
  
  	/* Reset the timer */
  	lastdec = READ_TIMER();
  	timestamp = 0;
  
  	return 0;
  }
  
  /*
   * timer without interrupts
   */
  ulong get_timer(ulong base)
  {
  	return (get_timer_masked() / GPT_RESOLUTION) - base;
  }
  
  void __udelay(unsigned long usec)
  {
  	ulong tmo;
  	ulong start = get_timer_masked();
  	ulong tenudelcnt = CONFIG_STV0991_HZ_CLOCK / (1000 * 100);
  	ulong rndoff;
  
  	rndoff = (usec % 10) ? 1 : 0;
  
  	/* tenudelcnt timer tick gives 10 microsecconds delay */
  	tmo = ((usec / 10) + rndoff) * tenudelcnt;
  
  	while ((ulong) (get_timer_masked() - start) < tmo)
  		;
  }
  
  static ulong get_timer_masked(void)
  {
  	ulong now = READ_TIMER();
  
  	if (now >= lastdec) {
  		/* normal mode */
  		timestamp += now - lastdec;
  	} else {
  		/* we have an overflow ... */
  		timestamp += now + GPT_FREE_RUNNING - lastdec;
  	}
  	lastdec = now;
  
  	return timestamp;
  }
  
  /*
   * This function is derived from PowerPC code (read timebase as long long).
   * On ARM it just returns the timer value.
   */
  unsigned long long get_ticks(void)
  {
  	return get_timer(0);
  }
  
  /*
   * This function is derived from PowerPC code (timebase clock frequency).
   * On ARM it returns the number of timer ticks per second.
   */
  ulong get_tbclk(void)
  {
  	return CONFIG_STV0991_HZ;
  }
  