From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH] clocksource/drivers/tegra: rework for compensation of suspend time Date: Tue, 2 Apr 2019 18:49:51 +0200 Message-ID: <20190402164951.GB7797@ulmo> References: <20190402030234.13488-1-josephl@nvidia.com> <20190402144603.GE8017@ulmo> <01028c3a-8e2e-835b-f886-ca5b85474cd2@nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="1UWUbFP1cBYEclgG" Return-path: Content-Disposition: inline In-Reply-To: <01028c3a-8e2e-835b-f886-ca5b85474cd2@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Joseph Lo Cc: Daniel Lezcano , linux-kernel@vger.kernel.org, Jonathan Hunter , linux-tegra@vger.kernel.org, Thomas Gleixner , linux-arm-kernel@lists.infradead.org List-Id: linux-tegra@vger.kernel.org --1UWUbFP1cBYEclgG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Apr 02, 2019 at 11:50:20PM +0800, Joseph Lo wrote: > On 4/2/19 10:46 PM, Thierry Reding wrote: > > On Tue, Apr 02, 2019 at 11:02:34AM +0800, Joseph Lo wrote: > > > Since the clocksource framework has the support for suspend time > > > compensation. Re-work the driver to use that, so we can reduce the > > > duplicate code. > > >=20 > > > Suggested-by: Daniel Lezcano > > > Signed-off-by: Joseph Lo > > > --- > > > drivers/clocksource/timer-tegra20.c | 63 +++++++++-----------------= --- > > > 1 file changed, 20 insertions(+), 43 deletions(-) > >=20 > > Nice! > >=20 > > >=20 > > > diff --git a/drivers/clocksource/timer-tegra20.c b/drivers/clocksourc= e/timer-tegra20.c > > > index fdb3d795a409..919b3568c495 100644 > > > --- a/drivers/clocksource/timer-tegra20.c > > > +++ b/drivers/clocksource/timer-tegra20.c > > > @@ -60,9 +60,6 @@ > > > static u32 usec_config; > > > static void __iomem *timer_reg_base; > > > #ifdef CONFIG_ARM > > > -static void __iomem *rtc_base; > > > -static struct timespec64 persistent_ts; > > > -static u64 persistent_ms, last_persistent_ms; > > > static struct delay_timer tegra_delay_timer; > > > #endif > > > @@ -199,40 +196,30 @@ static unsigned long tegra_delay_timer_read_cou= nter_long(void) > > > return readl(timer_reg_base + TIMERUS_CNTR_1US); > > > } > > > +static struct timer_of suspend_rtc_to =3D { > > > + .flags =3D TIMER_OF_BASE | TIMER_OF_CLOCK, > > > +}; > > > + > > > /* > > > * tegra_rtc_read - Reads the Tegra RTC registers > > > * Care must be taken that this funciton is not called while the > > > * tegra_rtc driver could be executing to avoid race conditions > > > * on the RTC shadow register > > > */ > > > -static u64 tegra_rtc_read_ms(void) > > > +static u64 tegra_rtc_read_ms(struct clocksource *cs) > > > { > > > - u32 ms =3D readl(rtc_base + RTC_MILLISECONDS); > > > - u32 s =3D readl(rtc_base + RTC_SHADOW_SECONDS); > > > + u32 ms =3D readl(timer_of_base(&suspend_rtc_to) + RTC_MILLISECONDS); > > > + u32 s =3D readl(timer_of_base(&suspend_rtc_to) + RTC_SHADOW_SECONDS= ); > > > return (u64)s * MSEC_PER_SEC + ms; > > > } > > > -/* > > > - * tegra_read_persistent_clock64 - Return time from a persistent cl= ock. > > > - * > > > - * Reads the time from a source which isn't disabled during PM, the > > > - * 32k sync timer. Convert the cycles elapsed since last read into > > > - * nsecs and adds to a monotonically increasing timespec64. > > > - * Care must be taken that this funciton is not called while the > > > - * tegra_rtc driver could be executing to avoid race conditions > > > - * on the RTC shadow register > > > - */ > > > -static void tegra_read_persistent_clock64(struct timespec64 *ts) > > > -{ > > > - u64 delta; > > > - > > > - last_persistent_ms =3D persistent_ms; > > > - persistent_ms =3D tegra_rtc_read_ms(); > > > - delta =3D persistent_ms - last_persistent_ms; > > > - > > > - timespec64_add_ns(&persistent_ts, delta * NSEC_PER_MSEC); > > > - *ts =3D persistent_ts; > > > -} > > > +static struct clocksource suspend_rtc_clocksource =3D { > > > + .name =3D "tegra_suspend_timer", > > > + .rating =3D 200, > > > + .read =3D tegra_rtc_read_ms, > > > + .mask =3D CLOCKSOURCE_MASK(32), > > > + .flags =3D CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTO= P, > > > +}; > > > #endif > > > static int tegra_timer_common_init(struct device_node *np, struct t= imer_of *to) > > > @@ -385,25 +372,15 @@ static int __init tegra_init_timer(struct devic= e_node *np) > > > static int __init tegra20_init_rtc(struct device_node *np) > > > { > > > - struct clk *clk; > > > + int ret; > > > - rtc_base =3D of_iomap(np, 0); > > > - if (!rtc_base) { > > > - pr_err("Can't map RTC registers\n"); > > > - return -ENXIO; > > > - } > > > + ret =3D timer_of_init(np, &suspend_rtc_to); > > > + if (ret) > > > + return ret; > > > - /* > > > - * rtc registers are used by read_persistent_clock, keep the rtc cl= ock > > > - * enabled > > > - */ > > > - clk =3D of_clk_get(np, 0); > > > - if (IS_ERR(clk)) > > > - pr_warn("Unable to get rtc-tegra clock\n"); > > > - else > > > - clk_prepare_enable(clk); > > > + clocksource_register_hz(&suspend_rtc_clocksource, 1000); > > > - return register_persistent_clock(tegra_read_persistent_clock64); > > > + return 0; > > > } > > > TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rt= c); > > > #endif > >=20 > > I wonder if there's any reason left for the #ifdefs now. My recollection > > is that these were only needed because register_persistent_clock() was > > not available on 64-bit ARM. The new APIs seem to be available > > regardless of architecture, so do we still need to differentiate? > >=20 >=20 > Actually, only Tegra20/30 that doesn't have ARM arch timer support need > this. The latter Tegra chips which have ARM arch timer support use TSC ( > time stamp counter or timer system counter depends on the chip it has > different name) as the timer source in the PMC. And it uses OSC during > runtime and switches to 32KHz always-on clock source to keep counting when > the chip is in the SC7 or LP0 state. >=20 > So I didn't change that for this reason. Okay, looks good then. 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