| Message ID | 1362049164-10297-2-git-send-email-akshay.s@samsung.com |
|---|---|
| State | Changes Requested |
| Delegated to: | Minkyu Kang |
| Headers | show |
Dear Akshay, On 28/02/13 19:59, Akshay Saraswat wrote: > At present get_timer() does not return sane values. It should count up > smoothly in milliscond intervals. > > We can change the PWM to count down at 1MHz, providing a resolution > of 1us and a range of about an hour between required get_timer() calls. > > Test with command "sf probe 1:0; time sf read 40008000 0 1000". > Try with different numbers of bytes and see that sane values are obtained > > Signed-off-by: Simon Glass <sjg@chromium.org> > Signed-off-by: Akshay Saraswat <akshay.s@samsung.com> > Acked-by: Simon Glass <sjg@chromium.org> > --- > Changes since v1: > - Added "Acked-by: Simon Glass". > > arch/arm/cpu/armv7/s5p-common/pwm.c | 6 ++ > arch/arm/cpu/armv7/s5p-common/timer.c | 100 +++++++++++++--------------------- > 2 files changed, 44 insertions(+), 62 deletions(-) > > diff --git a/arch/arm/cpu/armv7/s5p-common/pwm.c b/arch/arm/cpu/armv7/s5p-common/pwm.c > index 44d7bc3..3147f59 100644 > --- a/arch/arm/cpu/armv7/s5p-common/pwm.c > +++ b/arch/arm/cpu/armv7/s5p-common/pwm.c > @@ -174,6 +174,12 @@ int pwm_init(int pwm_id, int div, int invert) > > /* set count value */ > offset = pwm_id * 3; > + > + /* > + * TODO(sjg): Use this as a countdown timer for now. We count down > + * from the maximum value to 0, then reset. > + */ > + timer_rate_hz = -1; is it workaround? > writel(timer_rate_hz, &pwm->tcntb0 + offset); > > val = readl(&pwm->tcon) & ~(0xf << TCON_OFFSET(pwm_id)); > diff --git a/arch/arm/cpu/armv7/s5p-common/timer.c b/arch/arm/cpu/armv7/s5p-common/timer.c > index e78c716..c48a297 100644 > --- a/arch/arm/cpu/armv7/s5p-common/timer.c > +++ b/arch/arm/cpu/armv7/s5p-common/timer.c > @@ -39,13 +39,33 @@ static inline struct s5p_timer *s5p_get_base_timer(void) > return (struct s5p_timer *)samsung_get_base_timer(); > } > > +/** > + * Read the countdown timer. > + * > + * This operates at 1MHz and counts downwards. It will wrap about every > + * hour (2^32 microseconds). > + * > + * @return current value of timer > + */ > +static unsigned long timer_get_us_down(void) > +{ > + struct s5p_timer *const timer = s5p_get_base_timer(); > + > + return readl(&timer->tcnto4); > +} > + > int timer_init(void) > { > /* PWM Timer 4 */ > - pwm_init(4, MUX_DIV_2, 0); > + pwm_init(4, MUX_DIV_4, 0); There are special reason to change the div value? Please let me know. > pwm_config(4, 0, 0); > pwm_enable(4); > > + /* Use this as the current monotonic time in us */ > + gd->arch.timer_reset_value = 0; > + > + /* Use this as the last timer value we saw */ > + gd->arch.lastinc = timer_get_us_down(); > reset_timer_masked(); > > return 0; > @@ -56,48 +76,28 @@ int timer_init(void) > */ > unsigned long get_timer(unsigned long base) > { > - return get_timer_masked() - base; > + ulong now = timer_get_us_down(); > + > + /* > + * Increment the time by the amount elapsed since the last read. > + * The timer may have wrapped around, but it makes no difference to > + * our arithmetic here. > + */ > + gd->arch.timer_reset_value += gd->arch.lastinc - now; > + gd->arch.lastinc = now; > + > + /* Divide by 1000 to convert from us to ms */ > + return gd->arch.timer_reset_value / 1000 - base; > } > > /* delay x useconds */ > void __udelay(unsigned long usec) > { > - struct s5p_timer *const timer = s5p_get_base_timer(); > - unsigned long tmo, tmp, count_value; > - > - count_value = readl(&timer->tcntb4); > - > - if (usec >= 1000) { > - /* > - * if "big" number, spread normalization > - * to seconds > - * 1. start to normalize for usec to ticks per sec > - * 2. find number of "ticks" to wait to achieve target > - * 3. finish normalize. > - */ > - tmo = usec / 1000; > - tmo *= (CONFIG_SYS_HZ * count_value); > - tmo /= 1000; > - } else { > - /* else small number, don't kill it prior to HZ multiply */ > - tmo = usec * CONFIG_SYS_HZ * count_value; > - tmo /= (1000 * 1000); > - } > - > - /* get current timestamp */ > - tmp = get_current_tick(); > - > - /* if setting this fordward will roll time stamp */ > - /* reset "advancing" timestamp to 0, set lastinc value */ > - /* else, set advancing stamp wake up time */ > - if ((tmo + tmp + 1) < tmp) > - reset_timer_masked(); > - else > - tmo += tmp; > - > - /* loop till event */ > - while (get_current_tick() < tmo) > - ; /* nop */ > + unsigned long count_value; > + > + count_value = timer_get_us_down(); > + while ((int)(count_value - timer_get_us_down()) < (int)usec) why convert to int? > + ; > } > > void reset_timer_masked(void) > @@ -109,30 +109,6 @@ void reset_timer_masked(void) > gd->arch.tbl = 0; > } > > -unsigned long get_timer_masked(void) > -{ > - struct s5p_timer *const timer = s5p_get_base_timer(); > - unsigned long count_value = readl(&timer->tcntb4); > - > - return get_current_tick() / count_value; > -} > - > -unsigned long get_current_tick(void) > -{ > - struct s5p_timer *const timer = s5p_get_base_timer(); > - unsigned long now = readl(&timer->tcnto4); > - unsigned long count_value = readl(&timer->tcntb4); > - > - if (gd->arch.lastinc >= now) > - gd->arch.tbl += gd->arch.lastinc - now; > - else > - gd->arch.tbl += gd->arch.lastinc + count_value - now; > - > - gd->arch.lastinc = now; > - > - return gd->arch.tbl; > -} > - > /* > * This function is derived from PowerPC code (read timebase as long long). > * On ARM it just returns the timer value. > Thanks, Minkyu Kang.
diff --git a/arch/arm/cpu/armv7/s5p-common/pwm.c b/arch/arm/cpu/armv7/s5p-common/pwm.c index 44d7bc3..3147f59 100644 --- a/arch/arm/cpu/armv7/s5p-common/pwm.c +++ b/arch/arm/cpu/armv7/s5p-common/pwm.c @@ -174,6 +174,12 @@ int pwm_init(int pwm_id, int div, int invert) /* set count value */ offset = pwm_id * 3; + + /* + * TODO(sjg): Use this as a countdown timer for now. We count down + * from the maximum value to 0, then reset. + */ + timer_rate_hz = -1; writel(timer_rate_hz, &pwm->tcntb0 + offset); val = readl(&pwm->tcon) & ~(0xf << TCON_OFFSET(pwm_id)); diff --git a/arch/arm/cpu/armv7/s5p-common/timer.c b/arch/arm/cpu/armv7/s5p-common/timer.c index e78c716..c48a297 100644 --- a/arch/arm/cpu/armv7/s5p-common/timer.c +++ b/arch/arm/cpu/armv7/s5p-common/timer.c @@ -39,13 +39,33 @@ static inline struct s5p_timer *s5p_get_base_timer(void) return (struct s5p_timer *)samsung_get_base_timer(); } +/** + * Read the countdown timer. + * + * This operates at 1MHz and counts downwards. It will wrap about every + * hour (2^32 microseconds). + * + * @return current value of timer + */ +static unsigned long timer_get_us_down(void) +{ + struct s5p_timer *const timer = s5p_get_base_timer(); + + return readl(&timer->tcnto4); +} + int timer_init(void) { /* PWM Timer 4 */ - pwm_init(4, MUX_DIV_2, 0); + pwm_init(4, MUX_DIV_4, 0); pwm_config(4, 0, 0); pwm_enable(4); + /* Use this as the current monotonic time in us */ + gd->arch.timer_reset_value = 0; + + /* Use this as the last timer value we saw */ + gd->arch.lastinc = timer_get_us_down(); reset_timer_masked(); return 0; @@ -56,48 +76,28 @@ int timer_init(void) */ unsigned long get_timer(unsigned long base) { - return get_timer_masked() - base; + ulong now = timer_get_us_down(); + + /* + * Increment the time by the amount elapsed since the last read. + * The timer may have wrapped around, but it makes no difference to + * our arithmetic here. + */ + gd->arch.timer_reset_value += gd->arch.lastinc - now; + gd->arch.lastinc = now; + + /* Divide by 1000 to convert from us to ms */ + return gd->arch.timer_reset_value / 1000 - base; } /* delay x useconds */ void __udelay(unsigned long usec) { - struct s5p_timer *const timer = s5p_get_base_timer(); - unsigned long tmo, tmp, count_value; - - count_value = readl(&timer->tcntb4); - - if (usec >= 1000) { - /* - * if "big" number, spread normalization - * to seconds - * 1. start to normalize for usec to ticks per sec - * 2. find number of "ticks" to wait to achieve target - * 3. finish normalize. - */ - tmo = usec / 1000; - tmo *= (CONFIG_SYS_HZ * count_value); - tmo /= 1000; - } else { - /* else small number, don't kill it prior to HZ multiply */ - tmo = usec * CONFIG_SYS_HZ * count_value; - tmo /= (1000 * 1000); - } - - /* get current timestamp */ - tmp = get_current_tick(); - - /* if setting this fordward will roll time stamp */ - /* reset "advancing" timestamp to 0, set lastinc value */ - /* else, set advancing stamp wake up time */ - if ((tmo + tmp + 1) < tmp) - reset_timer_masked(); - else - tmo += tmp; - - /* loop till event */ - while (get_current_tick() < tmo) - ; /* nop */ + unsigned long count_value; + + count_value = timer_get_us_down(); + while ((int)(count_value - timer_get_us_down()) < (int)usec) + ; } void reset_timer_masked(void) @@ -109,30 +109,6 @@ void reset_timer_masked(void) gd->arch.tbl = 0; } -unsigned long get_timer_masked(void) -{ - struct s5p_timer *const timer = s5p_get_base_timer(); - unsigned long count_value = readl(&timer->tcntb4); - - return get_current_tick() / count_value; -} - -unsigned long get_current_tick(void) -{ - struct s5p_timer *const timer = s5p_get_base_timer(); - unsigned long now = readl(&timer->tcnto4); - unsigned long count_value = readl(&timer->tcntb4); - - if (gd->arch.lastinc >= now) - gd->arch.tbl += gd->arch.lastinc - now; - else - gd->arch.tbl += gd->arch.lastinc + count_value - now; - - gd->arch.lastinc = now; - - return gd->arch.tbl; -} - /* * This function is derived from PowerPC code (read timebase as long long). * On ARM it just returns the timer value.