[PATCH v2] ARM: S5P: Add System Timer

Lukasz Majewski l.majewski at samsung.com
Fri May 14 12:08:40 EDT 2010


Hello,

I've following comments:

> -----Original Message-----
> From: linux-samsung-soc-owner at vger.kernel.org [mailto:linux-samsung-
> soc-owner at vger.kernel.org] On Behalf Of Kukjin Kim
> Sent: Friday, May 14, 2010 10:52 AM
> To: linux-arm-kernel at lists.infradead.org; linux-samsung-
> soc at vger.kernel.org
> Cc: ben-linux at fluff.org; Jongpill Lee; Jongpill Lee; Kukjin Kim
> Subject: [PATCH v2] ARM: S5P: Add System Timer
> 
> From: Jongpill Lee <boyko at samsung.com>
> 
> This patch addes system timer for Samsung S5P series SoCs
> 
> Signed-off-by: Jongpill Lee <boyko.lee at samsung.com>
> Signed-off-by: Kukjin Kim <kgene.kim at samsung.com>
> ---
>  arch/arm/mach-s5p6442/include/mach/tick.h      |    6 +
>  arch/arm/mach-s5p6442/mach-smdk6442.c          |    2 +-
>  arch/arm/mach-s5pv210/include/mach/tick.h      |    6 +
>  arch/arm/mach-s5pv210/mach-smdkc110.c          |    2 +-
>  arch/arm/mach-s5pv210/mach-smdkv210.c          |    2 +-
>  arch/arm/plat-s5p/Kconfig                      |    7 +
>  arch/arm/plat-s5p/Makefile                     |    1 +
>  arch/arm/plat-s5p/include/plat/regs-systimer.h |   75 ++++++
>  arch/arm/plat-s5p/s5p-systimer.c               |  287
> ++++++++++++++++++++++++
>  arch/arm/plat-samsung/include/plat/cpu.h       |    3 +
>  10 files changed, 388 insertions(+), 3 deletions(-)
>  create mode 100644 arch/arm/plat-s5p/include/plat/regs-systimer.h
>  create mode 100644 arch/arm/plat-s5p/s5p-systimer.c
> 
> diff --git a/arch/arm/mach-s5p6442/include/mach/tick.h b/arch/arm/mach-
> s5p6442/include/mach/tick.h
> index e1d4cab..1795b43 100644
> --- a/arch/arm/mach-s5p6442/include/mach/tick.h
> +++ b/arch/arm/mach-s5p6442/include/mach/tick.h
> @@ -21,6 +21,12 @@ static inline u32 s3c24xx_ostimer_pending(void)
>  	return pend & (1 << (IRQ_TIMER4_VIC - S5P_IRQ_VIC0(0)));
>  }
> 
> +static inline u32 s5p_ostimer_pending(void)
> +{
> +	u32 pend = __raw_readl(VA_VIC0 + VIC_RAW_STATUS);
> +	return pend & (1 << (IRQ_SYSTIMER - S5P_IRQ_VIC0(0)));
> +}
> +
>  #define TICK_MAX	(0xffffffff)
> 
>  #endif /* __ASM_ARCH_TICK_H */
> diff --git a/arch/arm/mach-s5p6442/mach-smdk6442.c b/arch/arm/mach-
> s5p6442/mach-smdk6442.c
> index 0d63371..6c8728b 100644
> --- a/arch/arm/mach-s5p6442/mach-smdk6442.c
> +++ b/arch/arm/mach-s5p6442/mach-smdk6442.c
> @@ -87,5 +87,5 @@ MACHINE_START(SMDK6442, "SMDK6442")
>  	.init_irq	= s5p6442_init_irq,
>  	.map_io		= smdk6442_map_io,
>  	.init_machine	= smdk6442_machine_init,
> -	.timer		= &s3c24xx_timer,
> +	.timer		= &s5p_systimer,
>  MACHINE_END
> diff --git a/arch/arm/mach-s5pv210/include/mach/tick.h b/arch/arm/mach-
> s5pv210/include/mach/tick.h
> index 7993b36..9fc5a8d 100644
> --- a/arch/arm/mach-s5pv210/include/mach/tick.h
> +++ b/arch/arm/mach-s5pv210/include/mach/tick.h
> @@ -21,6 +21,12 @@ static inline u32 s3c24xx_ostimer_pending(void)
>  	return pend & (1 << (IRQ_TIMER4_VIC - S5P_IRQ_VIC0(0)));
>  }
> 
> +static inline u32 s5p_ostimer_pending(void)
> +{
> +	u32 pend = __raw_readl(VA_VIC0 + VIC_RAW_STATUS);
> +	return pend & (1 << (IRQ_SYSTIMER - S5P_IRQ_VIC0(0)));
> +}
> +
>  #define TICK_MAX	(0xffffffff)
> 
>  #endif /* __ASM_ARCH_TICK_H */
> diff --git a/arch/arm/mach-s5pv210/mach-smdkc110.c b/arch/arm/mach-
> s5pv210/mach-smdkc110.c
> index ab4869d..b520817 100644
> --- a/arch/arm/mach-s5pv210/mach-smdkc110.c
> +++ b/arch/arm/mach-s5pv210/mach-smdkc110.c
> @@ -94,5 +94,5 @@ MACHINE_START(SMDKC110, "SMDKC110")
>  	.init_irq	= s5pv210_init_irq,
>  	.map_io		= smdkc110_map_io,
>  	.init_machine	= smdkc110_machine_init,
> -	.timer		= &s3c24xx_timer,
> +	.timer		= &s5p_systimer,
>  MACHINE_END
> diff --git a/arch/arm/mach-s5pv210/mach-smdkv210.c b/arch/arm/mach-
> s5pv210/mach-smdkv210.c
> index a278832..2a29d47 100644
> --- a/arch/arm/mach-s5pv210/mach-smdkv210.c
> +++ b/arch/arm/mach-s5pv210/mach-smdkv210.c
> @@ -94,5 +94,5 @@ MACHINE_START(SMDKV210, "SMDKV210")
>  	.init_irq	= s5pv210_init_irq,
>  	.map_io		= smdkv210_map_io,
>  	.init_machine	= smdkv210_machine_init,
> -	.timer		= &s3c24xx_timer,
> +	.timer		= &s5p_systimer,
>  MACHINE_END
> diff --git a/arch/arm/plat-s5p/Kconfig b/arch/arm/plat-s5p/Kconfig
> index d400a6a..e152bbc 100644
> --- a/arch/arm/plat-s5p/Kconfig
> +++ b/arch/arm/plat-s5p/Kconfig
> @@ -23,3 +23,10 @@ config PLAT_S5P
>  	select SAMSUNG_IRQ_UART
>  	help
>  	  Base platform code for Samsung's S5P series SoC.
> +
> +config S5P_SYSTIMER
> +	bool
> +	depends on (ARCH_S5P6442 || ARCH_S5PV210)
> +	default y
> +	help
> +	  Support System Timer for S5P Series
> diff --git a/arch/arm/plat-s5p/Makefile b/arch/arm/plat-s5p/Makefile
> index 7f44678..dbc6595 100644
> --- a/arch/arm/plat-s5p/Makefile
> +++ b/arch/arm/plat-s5p/Makefile
> @@ -17,3 +17,4 @@ obj-y				+= cpu.o
>  obj-y				+= clock.o
>  obj-y				+= irq.o
>  obj-y				+= setup-i2c0.o
> +obj-$(CONFIG_S5P_SYSTIMER)	+= s5p-systimer.o
> diff --git a/arch/arm/plat-s5p/include/plat/regs-systimer.h
> b/arch/arm/plat-s5p/include/plat/regs-systimer.h
> new file mode 100644
> index 0000000..61f1282
> --- /dev/null
> +++ b/arch/arm/plat-s5p/include/plat/regs-systimer.h
> @@ -0,0 +1,75 @@
> +/* linux/arch/arm/plat-s5p/include/plat/regs-systimer.h
> + *
> + * Copyright (c) 2010 Samsung Electronics Co., Ltd.
> + *		http://www.samsung.com/
> + *
> + * S5P System Timer Driver Header information
> + *
> + * 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.
> +*/
> +
> +#ifndef __ASM_PLAT_REGS_SYSTIMER_H
> +#define __ASM_PLAT_REGS_SYSTIMER_H __FILE__
> +
> +#define S5P_SYSTIMERREG(x)		(S5P_VA_SYSTIMER + (x))
> +
> +#define S5P_SYSTIMER_TCFG		S5P_SYSTIMERREG(0x00)
> +#define S5P_SYSTIMER_TCON		S5P_SYSTIMERREG(0x04)
> +#define S5P_SYSTIMER_TICNTB		S5P_SYSTIMERREG(0x08)
> +#define S5P_SYSTIMER_TICNTO		S5P_SYSTIMERREG(0x0c)
> +#define S5P_SYSTIMER_TFCNTB		S5P_SYSTIMERREG(0x10)
> +#define S5P_SYSTIMER_ICNTB		S5P_SYSTIMERREG(0x18)
> +#define S5P_SYSTIMER_ICNTO		S5P_SYSTIMERREG(0x1c)
> +#define S5P_SYSTIMER_INT_CSTAT		S5P_SYSTIMERREG(0x20)
> +
> +/* Value for TCFG */
> +
> +#define S5P_SYSTIMER_SWRST		(1 << 16)
> +
> +#define S5P_SYSTIMER_DIV_GEN		(0 << 15)
> +#define S5P_SYSTIMER_DIV_RTC		(1 << 15)
> +
> +#define S5P_SYSTIMER_TICK_INT		(0 << 14)
> +#define S5P_SYSTIMER_TICK_FRA		(1 << 14)
> +
> +#define S5P_SYSTIMER_TCLK_MASK		(3 << 12)
> +#define S5P_SYSTIMER_TCLK_XXTI		(0 << 12)
> +#define S5P_SYSTIMER_TCLK_RTC		(1 << 12)
> +#define S5P_SYSTIMER_TCLK_USB		(2 << 12)
> +#define S5P_SYSTIMER_TCLK_PCLK		(3 << 12)
> +
> +#define S5P_SYSTIMER_DIV_MASK		(7 << 8)
> +#define S5P_SYSTIMER_DIV_1		(0 << 8)
> +#define S5P_SYSTIMER_DIV_2		(1 << 8)
> +#define S5P_SYSTIMER_DIV_4		(2 << 8)
> +#define S5P_SYSTIMER_DIV_8		(3 << 8)
> +#define S5P_SYSTIMER_DIV_16		(4 << 8)
> +
> +#define S5P_SYSTIMER_TARGET_HZ		1000
> +#define S5P_SYSTIMER_PRESCALER		5
> +#define S5P_SYSTIMER_PRESCALER_MASK	(0x3f << 0)
> +
> +/* value for TCON */
> +
> +#define S5P_SYSTIMER_INT_AUTO		(1 << 5)
> +#define S5P_SYSTIMER_INT_IMM		(1 << 4)
> +#define S5P_SYSTIMER_INT_START		(1 << 3)
> +#define S5P_SYSTIMER_START		(1 << 0)
> +
> +/* Value for INT_CSTAT */
> +
> +#define S5P_SYSTIMER_INT_TWIE		(1 << 10)
> +#define S5P_SYSTIMER_INT_IWIE		(1 << 9)
> +#define S5P_SYSTIMER_INT_TFWIE		(1 << 8)
> +#define S5P_SYSTIMER_INT_TIWIE		(1 << 7)
> +#define S5P_SYSTIMER_INT_ICNTEIE	(1 << 6)
> +#define S5P_SYSTIMER_INT_TCON		(1 << 5)
> +#define S5P_SYSTIMER_INT_ICNTB		(1 << 4)
> +#define S5P_SYSTIMER_INT_TFCNTB		(1 << 3)
> +#define S5P_SYSTIMER_INT_TICNTB		(1 << 2)
> +#define S5P_SYSTIMER_INT_INTCNT		(1 << 1)
> +#define S5P_SYSTIMER_INT_INTENABLE	(1 << 0)
> +
> +#endif /* __ASM_PLAT_REGS_SYSTIMER_H */
> diff --git a/arch/arm/plat-s5p/s5p-systimer.c b/arch/arm/plat-s5p/s5p-
> systimer.c
> new file mode 100644
> index 0000000..f0e4ec8
> --- /dev/null
> +++ b/arch/arm/plat-s5p/s5p-systimer.c
> @@ -0,0 +1,287 @@
> +/* linux/arch/arm/plat-s5p/s5p-systimer.c
> + *
> + * Copyright (c) 2010 Samsung Electronics Co., Ltd.
> + *		http://www.samsung.com/
> + *
> + * S5P System Timer
> + *
> + * Based on linux/arch/arm/plat-samsung/time.c
> + *
> + * 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.
> +*/
> +
> +#include <linux/kernel.h>
> +#include <linux/sched.h>
> +#include <linux/init.h>
> +#include <linux/errno.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +
> +#include <asm/system.h>
> +#include <asm/mach-types.h>
> +
> +#include <asm/irq.h>
> +#include <asm/mach/time.h>
> +
> +#include <mach/map.h>
> +#include <mach/regs-irq.h>
> +#include <mach/tick.h>
> +
> +#include <plat/regs-systimer.h>
> +#include <plat/clock.h>
> +#include <plat/cpu.h>
> +
> +#include <mach/regs-clock.h>
> +
> +static unsigned long timer_startval;
> +static unsigned long timer_usec_ticks;
> +static unsigned long timer_icnt;
> +
> +#define TICK_MAX		(0xffffffff)
> +#define TIMER_USEC_SHIFT	16
> +
> +static unsigned int systimer_write_done(unsigned int value)
> +{
> +	unsigned int cnt;
> +	unsigned int tmp_reg;
> +
> +	cnt = 1000;
> +
> +	do {
> +		if (__raw_readl(S5P_SYSTIMER_INT_CSTAT) & value) {
> +			tmp_reg = __raw_readl(S5P_SYSTIMER_INT_CSTAT);
> +			tmp_reg |= value;
> +			__raw_writel(tmp_reg , S5P_SYSTIMER_INT_CSTAT);
> +
> +			return 0;
> +		}
> +	} while (--cnt > 0);
> +
> +	printk(KERN_ERR "%s : %d : Timer Expired\n", __func__, value);
> +
> +	return -ETIME;
> +}
> +
> +static unsigned int s5p_systimer_write(void __iomem *reg,
> +				       unsigned int value)
> +{
> +	unsigned int int_cstat;
> +	unsigned int ret = 0;
> +
> +	__raw_writel(value, reg);
> +
> +	int_cstat = __raw_readl(S5P_SYSTIMER_INT_CSTAT);
> +
> +	if (reg == S5P_SYSTIMER_TCON) {
> +		if (int_cstat & S5P_SYSTIMER_INT_TWIE)
> +			ret = systimer_write_done(S5P_SYSTIMER_INT_TCON);
> +
> +	} else if (reg == S5P_SYSTIMER_ICNTB) {
> +		if (int_cstat & S5P_SYSTIMER_INT_IWIE)
> +			ret = systimer_write_done(S5P_SYSTIMER_INT_ICNTB);
> +
> +	} else if (reg == S5P_SYSTIMER_TFCNTB) {
> +		if (int_cstat & S5P_SYSTIMER_INT_TFWIE)
> +			ret = systimer_write_done(S5P_SYSTIMER_INT_TFCNTB);
> +
> +	} else if (reg == S5P_SYSTIMER_TICNTB) {
> +		if (int_cstat & S5P_SYSTIMER_INT_TIWIE)
> +			ret = systimer_write_done(S5P_SYSTIMER_INT_TICNTB);
> +	}
> +
> +	return ret;
> +}
> +
> +/*
> + * S5P has system timer to use as OS tick Timer.
> + * System Timer provides two distincive feature. Accurate timer which
> provides
> + * exact 1ms time tick at any power mode except sleep mode.
> + * interrupt interval without stopping reference tick timer.
> + */
> +
> +/*
> + * timer_mask_usec_ticks
> + *
> + * given a clock and divisor, make the value to pass into
> timer_ticks_to_usec
> + * to scale the ticks into usecs
> + */
> +static inline unsigned long timer_mask_usec_ticks(unsigned long
> scaler,
> +						  unsigned long pclk)
> +{
> +	unsigned long den = pclk / 1000;
> +
> +	return ((1000 << TIMER_USEC_SHIFT) * scaler + (den >> 1)) / den;
> +}
> +
> +/*
> + * timer_ticks_to_usec
> + *
> + * convert timer ticks to usec.
> + */
> +static inline unsigned long timer_ticks_to_usec(unsigned long ticks)
> +{
> +	unsigned long res;
> +
> +	res = ticks * timer_usec_ticks;
> +	res += 1 << (TIMER_USEC_SHIFT - 4);	/* round up slightly */
> +
> +	return res >> TIMER_USEC_SHIFT;
> +}
> +
> +/*
> + * Returns microsecond  since last clock interrupt.  Note that
> interrupts
> + * will have been disabled by do_gettimeoffset()
> + * IRQs are disabled before entering here from do_gettimeofday()
> + */
> +static unsigned long s5p_gettimeoffset(void)
> +{
> +	unsigned long tdone;
> +	unsigned long tval;
> +	unsigned long clk_tick_totcnt;
> +
> +	clk_tick_totcnt = (timer_icnt + 1) * timer_startval;
> +
> +	/* work out how many ticks have gone since last timer interrupt
> */
> +	tval = __raw_readl(S5P_SYSTIMER_ICNTO) * timer_startval;
> +	tval += __raw_readl(S5P_SYSTIMER_TICNTO);
> +
> +	tdone = clk_tick_totcnt - tval;
> +
> +	/* check to see if there is an interrupt pending */
> +	if (s5p_ostimer_pending()) {
> +		/* re-read the timer, and try and fix up for the missed
> +		 * interrupt. Note, the interrupt may go off before the
> +		 * timer has re-loaded from wrapping.
> +		 */
> +
> +		tval = __raw_readl(S5P_SYSTIMER_ICNTO) * timer_startval;
> +		tval += __raw_readl(S5P_SYSTIMER_TICNTO);
> +
> +		tdone = clk_tick_totcnt - tval;
> +
> +		if (tval != 0)
> +			tdone += clk_tick_totcnt;
> +	}
> +
> +	return timer_ticks_to_usec(tdone);
> +}
> +
> +/*
> + * IRQ handler for the timer
> + */
> +static irqreturn_t s5p_systimer_interrupt(int irq, void *dev_id)
> +{
> +	unsigned int temp_cstat;
> +
> +	temp_cstat = __raw_readl(S5P_SYSTIMER_INT_CSTAT);
> +	temp_cstat |= S5P_SYSTIMER_INT_INTCNT;
> +	s5p_systimer_write(S5P_SYSTIMER_INT_CSTAT, temp_cstat);
> +
> +	timer_tick();
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static struct irqaction s5p_systimer_irq = {
> +	.name		= "S5P System Timer",
> +	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
> +	.handler	= s5p_systimer_interrupt,
> +};
> +
> +/*
> + * Set up timer interrupt, and return the current time in seconds.
> + */
> +static void s5p_systimer_setup(void)
> +{
> +	unsigned long tcon;
> +	unsigned long tcnt;
> +	unsigned long tcfg;
> +	unsigned long int_csata;
> +
> +	/* clock configuration setting and enable */
> +	unsigned long pclk;
> +	struct clk *clk;
> +
> +	clk = clk_get(NULL, "systimer");
> +	if (IS_ERR(clk))
> +		panic("failed to get clock for system timer");
> +
> +	clk_enable(clk);
> +
> +	pclk = clk_get_rate(clk);
> +
> +	tcfg = __raw_readl(S5P_SYSTIMER_TCFG);
> +	tcfg |= S5P_SYSTIMER_SWRST;
> +	s5p_systimer_write(S5P_SYSTIMER_TCFG, tcfg);
> +
> +	tcnt = TICK_MAX;  /* default value for tcnt */
> +
> +	/* initialize system timer clock */
> +	tcfg = __raw_readl(S5P_SYSTIMER_TCFG);
> +
> +	tcfg &= ~S5P_SYSTIMER_TCLK_MASK;
> +	tcfg |= S5P_SYSTIMER_TCLK_PCLK;
> +
> +	s5p_systimer_write(S5P_SYSTIMER_TCFG, tcfg);
> +
> +	/* TCFG must not be changed at run-time.
> +	 * If you want to change TCFG, stop timer(TCON[0] = 0)
> +	 */
> +
> +	s5p_systimer_write(S5P_SYSTIMER_TCON, 0);
> +
> +	/* read the current timer configuration bits */
> +	tcon = __raw_readl(S5P_SYSTIMER_TCON);
> +	tcfg = __raw_readl(S5P_SYSTIMER_TCFG);
> +
> +	/* configure clock tick */
> +	timer_usec_ticks = timer_mask_usec_ticks(S5P_SYSTIMER_PRESCALER,
> pclk);
> +
> +	tcfg &= ~S5P_SYSTIMER_TCLK_MASK;
> +	tcfg |= S5P_SYSTIMER_TCLK_PCLK;

Here the PCLK clock is used to feed the SYSTEM TIMER.
Maybe it would be worth to use other (not system dependent and always
available) 
clock source - for instance the main processor clock?

And additionally it would be welcome to add this clock selection to the
overall clock API? (with use of e.g. clock_set/get_parent)

Is there any plan to do that?


> +	tcfg &= ~S5P_SYSTIMER_PRESCALER_MASK;
> +	tcfg |= S5P_SYSTIMER_PRESCALER - 1;
> +
> +	tcnt = ((pclk / S5P_SYSTIMER_PRESCALER) / S5P_SYSTIMER_TARGET_HZ)
> - 1;
> +
> +	/* check to see if timer is within 16bit range... */
> +	if (tcnt > TICK_MAX) {
> +		panic("setup_timer: HZ is too small, cannot configure
> timer!");
> +		return;
> +	}
> +
> +	s5p_systimer_write(S5P_SYSTIMER_TCFG, tcfg);
> +
> +	timer_startval = tcnt;
> +	s5p_systimer_write(S5P_SYSTIMER_TICNTB, tcnt);
> +
> +	/* set Interrupt tick value */
> +	timer_icnt = (S5P_SYSTIMER_TARGET_HZ / HZ) - 1;
> +	s5p_systimer_write(S5P_SYSTIMER_ICNTB, timer_icnt);
> +
> +	tcon = (S5P_SYSTIMER_INT_AUTO | S5P_SYSTIMER_START
> +		| S5P_SYSTIMER_INT_START);
> +	s5p_systimer_write(S5P_SYSTIMER_TCON, tcon);
> +
> +	/* Interrupt Start and Enable */
> +	int_csata = __raw_readl(S5P_SYSTIMER_INT_CSTAT);
> +	int_csata |= (S5P_SYSTIMER_INT_ICNTEIE |
> S5P_SYSTIMER_INT_INTENABLE);
> +	s5p_systimer_write(S5P_SYSTIMER_INT_CSTAT, int_csata);
> +}
> +
> +static void __init s5p_systimer_init(void)
> +{
> +	s5p_systimer_setup();
> +	setup_irq(IRQ_SYSTIMER, &s5p_systimer_irq);
> +}
> +
> +struct sys_timer s5p_systimer = {
> +	.init		= s5p_systimer_init,
> +	.offset		= s5p_gettimeoffset,
> +	.resume		= s5p_systimer_setup
> +};
> diff --git a/arch/arm/plat-samsung/include/plat/cpu.h b/arch/arm/plat-
> samsung/include/plat/cpu.h
> index c54f318..d1ec201 100644
> --- a/arch/arm/plat-samsung/include/plat/cpu.h
> +++ b/arch/arm/plat-samsung/include/plat/cpu.h
> @@ -68,6 +68,9 @@ extern void s3c24xx_init_uartdevs(char *name,
>  struct sys_timer;
>  extern struct sys_timer s3c24xx_timer;
> 
> +/* timer for s5p */
> +extern struct sys_timer s5p_systimer;
> +
>  /* system device classes */
> 
>  extern struct sysdev_class s3c2410_sysclass;
> --
> 1.6.2.5
> 
> --
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Best regards,

Lukasz Majewski
Samsung Poland R&D Center
Platform Group








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