| Message ID | 1454650952-20154-2-git-send-email-lokeshvutla@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Lokesh I apologize for the delay. A few comments: On Fri, 5 Feb 2016, Lokesh Vutla wrote: > RTC IP have kicker feature which prevents spurious writes to its registers. > In order to write into any of the RTC registers, KICK values has to be > written to KICK registers. > Introduce omap_hwmod_rtc_unlock/lock functions, which writes into these > KICK registers inorder to lock and unlock RTC registers. > > Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> > --- ... > +/** > + * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag > + * @oh: struct omap_hwmod * > + * > + * For updating certain RTC registers, the MPU must wait > + * for the BUSY status in OMAP_RTC_STATUS_REG to become zero. > + * Once the BUSY status is zero, there is a 15-?s access Probably best just to write out "microseconds" or "us" here to avoid the high-bit character problem. > + * period in which the MPU can program. > + */ > +static void omap_rtc_wait_not_busy(struct omap_hwmod *oh) > +{ > + int i; > + > + /* BUSY may stay active for 1/32768 second (~30 usec) */ > + omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG) > + & OMAP_RTC_STATUS_REG, OMAP_RTC_MAX_READY_TIME, i); This test looks bogus. Shouldn't it AND the register value with OMAP_RTC_STATUS_BUSY? Right now the code is AND-ing with 0x44, which doesn't include the BUSY bit. So I guess the tests that you mentioned in the first message of the series don't cover the BUSY case? > + /* now we have ~15 usec to read/write various registers */ > +} > + > +/** > + * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism. > + * @oh: struct omap_hwmod * > + * > + * RTC IP have kicker feature. This prevents spurious writes to its registers. > + * In order to write into any of the RTC registers, KICK values has te be > + * written in respective KICK registers. This is needed for hwmod to write into > + * sysconfig register. > + */ > +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh) > +{ > + local_irq_disable(); > + omap_rtc_wait_not_busy(oh); > + omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG); > + omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG); > + local_irq_enable(); Finally, could you ask the IP block maintainer to confirm the interpretation that, for any STATUS_REG read where the BUSY bit is 0, that we are guaranteed to have at least 15 microseconds from that point in time to access the IP block? It appears to be this way from my reading of the TRM; but to me, the phrasing is not explicit. Another interpretation could be that the BUSY bit reflects the IP block's current status. If this latter case is true, then to ensure that the IP block accesses complete inside the access window, we'll either need to test the BUSY bit after the writes to ensure that it is still 0, and otherwise repeat the busy test and writes; or we'll need to wait for a 0->1 BUSY transition before we wait for a 1->0 BUSY transition. > +} > + > +/** > + * omap_hwmod_rtc_lock - Lock the Kicker mechanism. > + * @oh: struct omap_hwmod * > + * > + * RTC IP have kicker feature. This prevents spurious writes to its registers. > + * Once the RTC registers are written, KICK mechanism needs to be locked, > + * in order to prevent any spurious writes. This function locks back the RTC > + * registers once hwmod completes its write into sysconfig register. > + */ > +void omap_hwmod_rtc_lock(struct omap_hwmod *oh) > +{ > + local_irq_disable(); > + omap_rtc_wait_not_busy(oh); > + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG); > + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG); > + local_irq_enable(); > +} > -- > 2.1.4 > - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Lokesh On Sun, 7 Feb 2016, Paul Walmsley wrote: > A few comments: > > On Fri, 5 Feb 2016, Lokesh Vutla wrote: > > > RTC IP have kicker feature which prevents spurious writes to its registers. > > In order to write into any of the RTC registers, KICK values has to be > > written to KICK registers. > > Introduce omap_hwmod_rtc_unlock/lock functions, which writes into these > > KICK registers inorder to lock and unlock RTC registers. > > > > Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> > > --- > > ... > > > +/** > > + * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag > > + * @oh: struct omap_hwmod * > > + * > > + * For updating certain RTC registers, the MPU must wait > > + * for the BUSY status in OMAP_RTC_STATUS_REG to become zero. > > + * Once the BUSY status is zero, there is a 15-?s access > > Probably best just to write out "microseconds" or "us" here to avoid the > high-bit character problem. > > > + * period in which the MPU can program. > > + */ > > +static void omap_rtc_wait_not_busy(struct omap_hwmod *oh) > > +{ > > + int i; > > + > > + /* BUSY may stay active for 1/32768 second (~30 usec) */ > > + omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG) > > + & OMAP_RTC_STATUS_REG, OMAP_RTC_MAX_READY_TIME, i); > > This test looks bogus. Shouldn't it AND the register value with > OMAP_RTC_STATUS_BUSY? Right now the code is AND-ing with 0x44, which > doesn't include the BUSY bit. So I guess the tests that you mentioned in > the first message of the series don't cover the BUSY case? > > > + /* now we have ~15 usec to read/write various registers */ > > +} > > + > > +/** > > + * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism. > > + * @oh: struct omap_hwmod * > > + * > > + * RTC IP have kicker feature. This prevents spurious writes to its registers. > > + * In order to write into any of the RTC registers, KICK values has te be > > + * written in respective KICK registers. This is needed for hwmod to write into > > + * sysconfig register. > > + */ > > +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh) > > +{ > > + local_irq_disable(); > > + omap_rtc_wait_not_busy(oh); > > + omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG); > > + omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG); > > + local_irq_enable(); > > Finally, could you ask the IP block maintainer to confirm the > interpretation that, for any STATUS_REG read where the BUSY bit is 0, that > we are guaranteed to have at least 15 microseconds from that point in time > to access the IP block? It appears to be this way from my reading of the > TRM; but to me, the phrasing is not explicit. Another interpretation > could be that the BUSY bit reflects the IP block's current status. If > this latter case is true, then to ensure that the IP block accesses > complete inside the access window, we'll either need to test the BUSY bit > after the writes to ensure that it is still 0, and otherwise repeat the > busy test and writes; or we'll need to wait for a 0->1 BUSY transition > before we wait for a 1->0 BUSY transition. > > > +} > > + > > +/** > > + * omap_hwmod_rtc_lock - Lock the Kicker mechanism. > > + * @oh: struct omap_hwmod * > > + * > > + * RTC IP have kicker feature. This prevents spurious writes to its registers. > > + * Once the RTC registers are written, KICK mechanism needs to be locked, > > + * in order to prevent any spurious writes. This function locks back the RTC > > + * registers once hwmod completes its write into sysconfig register. > > + */ > > +void omap_hwmod_rtc_lock(struct omap_hwmod *oh) > > +{ > > + local_irq_disable(); > > + omap_rtc_wait_not_busy(oh); > > + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG); > > + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG); > > + local_irq_enable(); > > +} Any update? - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Paul, On 2/18/2016 11:57 AM, Paul Walmsley wrote: > Hi Lokesh > > On Sun, 7 Feb 2016, Paul Walmsley wrote: > >> A few comments: >> >> On Fri, 5 Feb 2016, Lokesh Vutla wrote: >> >>> RTC IP have kicker feature which prevents spurious writes to its registers. >>> In order to write into any of the RTC registers, KICK values has to be >>> written to KICK registers. >>> Introduce omap_hwmod_rtc_unlock/lock functions, which writes into these >>> KICK registers inorder to lock and unlock RTC registers. >>> >>> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> >>> --- >> >> ... >> >>> +/** >>> + * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag >>> + * @oh: struct omap_hwmod * >>> + * >>> + * For updating certain RTC registers, the MPU must wait >>> + * for the BUSY status in OMAP_RTC_STATUS_REG to become zero. >>> + * Once the BUSY status is zero, there is a 15-?s access >> >> Probably best just to write out "microseconds" or "us" here to avoid the >> high-bit character problem. >> >>> + * period in which the MPU can program. >>> + */ >>> +static void omap_rtc_wait_not_busy(struct omap_hwmod *oh) >>> +{ >>> + int i; >>> + >>> + /* BUSY may stay active for 1/32768 second (~30 usec) */ >>> + omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG) >>> + & OMAP_RTC_STATUS_REG, OMAP_RTC_MAX_READY_TIME, i); >> >> This test looks bogus. Shouldn't it AND the register value with >> OMAP_RTC_STATUS_BUSY? Right now the code is AND-ing with 0x44, which >> doesn't include the BUSY bit. So I guess the tests that you mentioned in >> the first message of the series don't cover the BUSY case? >> >>> + /* now we have ~15 usec to read/write various registers */ >>> +} >>> + >>> +/** >>> + * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism. >>> + * @oh: struct omap_hwmod * >>> + * >>> + * RTC IP have kicker feature. This prevents spurious writes to its registers. >>> + * In order to write into any of the RTC registers, KICK values has te be >>> + * written in respective KICK registers. This is needed for hwmod to write into >>> + * sysconfig register. >>> + */ >>> +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh) >>> +{ >>> + local_irq_disable(); >>> + omap_rtc_wait_not_busy(oh); >>> + omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG); >>> + omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG); >>> + local_irq_enable(); >> >> Finally, could you ask the IP block maintainer to confirm the >> interpretation that, for any STATUS_REG read where the BUSY bit is 0, that >> we are guaranteed to have at least 15 microseconds from that point in time >> to access the IP block? It appears to be this way from my reading of the >> TRM; but to me, the phrasing is not explicit. Another interpretation >> could be that the BUSY bit reflects the IP block's current status. If >> this latter case is true, then to ensure that the IP block accesses >> complete inside the access window, we'll either need to test the BUSY bit >> after the writes to ensure that it is still 0, and otherwise repeat the >> busy test and writes; or we'll need to wait for a 0->1 BUSY transition >> before we wait for a 1->0 BUSY transition. >> >>> +} >>> + >>> +/** >>> + * omap_hwmod_rtc_lock - Lock the Kicker mechanism. >>> + * @oh: struct omap_hwmod * >>> + * >>> + * RTC IP have kicker feature. This prevents spurious writes to its registers. >>> + * Once the RTC registers are written, KICK mechanism needs to be locked, >>> + * in order to prevent any spurious writes. This function locks back the RTC >>> + * registers once hwmod completes its write into sysconfig register. >>> + */ >>> +void omap_hwmod_rtc_lock(struct omap_hwmod *oh) >>> +{ >>> + local_irq_disable(); >>> + omap_rtc_wait_not_busy(oh); >>> + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG); >>> + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG); >>> + local_irq_enable(); >>> +} > > Any update? Sorry for the delay, I am on a vacation right now. I have already sent a mail to the HW guys. Will update you as soon as I receive a reply from them. Thanks and regards, Lokesh > > > - Paul > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 18 Feb 2016, Lokesh Vutla wrote: > Sorry for the delay, I am on a vacation right now. I have already sent > a mail to the HW guys. Will update you as soon as I receive a reply > from them. Got it; thanks Lokesh. - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Paul, On Monday 08 February 2016 03:54 AM, Paul Walmsley wrote: > Hi Lokesh > > I apologize for the delay. > > A few comments: > > On Fri, 5 Feb 2016, Lokesh Vutla wrote: > >> RTC IP have kicker feature which prevents spurious writes to its registers. >> In order to write into any of the RTC registers, KICK values has to be >> written to KICK registers. >> Introduce omap_hwmod_rtc_unlock/lock functions, which writes into these >> KICK registers inorder to lock and unlock RTC registers. >> >> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> >> --- > > ... > >> +/** >> + * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag >> + * @oh: struct omap_hwmod * >> + * >> + * For updating certain RTC registers, the MPU must wait >> + * for the BUSY status in OMAP_RTC_STATUS_REG to become zero. >> + * Once the BUSY status is zero, there is a 15-?s access > > Probably best just to write out "microseconds" or "us" here to avoid the > high-bit character problem. > >> + * period in which the MPU can program. >> + */ >> +static void omap_rtc_wait_not_busy(struct omap_hwmod *oh) >> +{ >> + int i; >> + >> + /* BUSY may stay active for 1/32768 second (~30 usec) */ >> + omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG) >> + & OMAP_RTC_STATUS_REG, OMAP_RTC_MAX_READY_TIME, i); > > This test looks bogus. Shouldn't it AND the register value with > OMAP_RTC_STATUS_BUSY? Right now the code is AND-ing with 0x44, which > doesn't include the BUSY bit. So I guess the tests that you mentioned in > the first message of the series don't cover the BUSY case? > >> + /* now we have ~15 usec to read/write various registers */ >> +} >> + >> +/** >> + * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism. >> + * @oh: struct omap_hwmod * >> + * >> + * RTC IP have kicker feature. This prevents spurious writes to its registers. >> + * In order to write into any of the RTC registers, KICK values has te be >> + * written in respective KICK registers. This is needed for hwmod to write into >> + * sysconfig register. >> + */ >> +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh) >> +{ >> + local_irq_disable(); >> + omap_rtc_wait_not_busy(oh); >> + omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG); >> + omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG); >> + local_irq_enable(); > > Finally, could you ask the IP block maintainer to confirm the > interpretation that, for any STATUS_REG read where the BUSY bit is 0, that > we are guaranteed to have at least 15 microseconds from that point in time > to access the IP block? It appears to be this way from my reading of the > TRM; but to me, the phrasing is not explicit. Another interpretation > could be that the BUSY bit reflects the IP block's current status. If > this latter case is true, then to ensure that the IP block accesses > complete inside the access window, we'll either need to test the BUSY bit > after the writes to ensure that it is still 0, and otherwise repeat the > busy test and writes; or we'll need to wait for a 0->1 BUSY transition > before we wait for a 1->0 BUSY transition. As per the HW folks, once SW sees the transistion from 1->0, it is guaranteed that SW has 15.25 us to do all the write transactions for all the TC updates. Also as per TRM, in RTC there are three types of registers: -> TC registers and TC alarm registers: -> General registers -> Compensation registers. MPU must wait for the BUSY bit for accessing the TC registers and MPU can access the general registers at any point of time. SYSCONFIG, KICK registers comes under general registers. Since hwmod modifies only the sysconfig register, this omap_rtc_wait_not_busy() is not required here. We can directly write into sysconfig and KICK registers. Does this sound fine to you? Shall I resend this patch without omap_rtc_wait_not_busy()? Thanks and regards, Lokesh > >> +} >> + >> +/** >> + * omap_hwmod_rtc_lock - Lock the Kicker mechanism. >> + * @oh: struct omap_hwmod * >> + * >> + * RTC IP have kicker feature. This prevents spurious writes to its registers. >> + * Once the RTC registers are written, KICK mechanism needs to be locked, >> + * in order to prevent any spurious writes. This function locks back the RTC >> + * registers once hwmod completes its write into sysconfig register. >> + */ >> +void omap_hwmod_rtc_lock(struct omap_hwmod *oh) >> +{ >> + local_irq_disable(); >> + omap_rtc_wait_not_busy(oh); >> + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG); >> + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG); >> + local_irq_enable(); >> +} >> -- >> 2.1.4 >> > > > - Paul > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Lokesh, On Wed, 24 Feb 2016, Lokesh Vutla wrote: > On Monday 08 February 2016 03:54 AM, Paul Walmsley wrote: > > On Fri, 5 Feb 2016, Lokesh Vutla wrote: > > > >> RTC IP have kicker feature which prevents spurious writes to its registers. > >> In order to write into any of the RTC registers, KICK values has to be > >> written to KICK registers. > >> Introduce omap_hwmod_rtc_unlock/lock functions, which writes into these > >> KICK registers inorder to lock and unlock RTC registers. > >> > >> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> > >> --- > > > > ... > > > >> +/** > >> + * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag > >> + * @oh: struct omap_hwmod * > >> + * > >> + * For updating certain RTC registers, the MPU must wait > >> + * for the BUSY status in OMAP_RTC_STATUS_REG to become zero. > >> + * Once the BUSY status is zero, there is a 15-?s access > > > > Probably best just to write out "microseconds" or "us" here to avoid the > > high-bit character problem. > > > >> + * period in which the MPU can program. > >> + */ > >> +static void omap_rtc_wait_not_busy(struct omap_hwmod *oh) > >> +{ > >> + int i; > >> + > >> + /* BUSY may stay active for 1/32768 second (~30 usec) */ > >> + omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG) > >> + & OMAP_RTC_STATUS_REG, OMAP_RTC_MAX_READY_TIME, i); > > > > This test looks bogus. Shouldn't it AND the register value with > > OMAP_RTC_STATUS_BUSY? Right now the code is AND-ing with 0x44, which > > doesn't include the BUSY bit. So I guess the tests that you mentioned in > > the first message of the series don't cover the BUSY case? > > > >> + /* now we have ~15 usec to read/write various registers */ > >> +} > >> + > >> +/** > >> + * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism. > >> + * @oh: struct omap_hwmod * > >> + * > >> + * RTC IP have kicker feature. This prevents spurious writes to its registers. > >> + * In order to write into any of the RTC registers, KICK values has te be > >> + * written in respective KICK registers. This is needed for hwmod to write into > >> + * sysconfig register. > >> + */ > >> +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh) > >> +{ > >> + local_irq_disable(); > >> + omap_rtc_wait_not_busy(oh); > >> + omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG); > >> + omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG); > >> + local_irq_enable(); > > > > Finally, could you ask the IP block maintainer to confirm the > > interpretation that, for any STATUS_REG read where the BUSY bit is 0, that > > we are guaranteed to have at least 15 microseconds from that point in time > > to access the IP block? It appears to be this way from my reading of the > > TRM; but to me, the phrasing is not explicit. Another interpretation > > could be that the BUSY bit reflects the IP block's current status. If > > this latter case is true, then to ensure that the IP block accesses > > complete inside the access window, we'll either need to test the BUSY bit > > after the writes to ensure that it is still 0, and otherwise repeat the > > busy test and writes; or we'll need to wait for a 0->1 BUSY transition > > before we wait for a 1->0 BUSY transition. > > As per the HW folks, once SW sees the transistion from 1->0, it is > guaranteed that SW has 15.25 us to do all the write transactions for all > the TC updates. Great > Also as per TRM, in RTC there are three types of registers: > -> TC registers and TC alarm registers: > -> General registers > -> Compensation registers. > > MPU must wait for the BUSY bit for accessing the TC registers and MPU > can access the general registers at any point of time. SYSCONFIG, KICK > registers comes under general registers. Since hwmod modifies only the > sysconfig register, this omap_rtc_wait_not_busy() is not required here. > We can directly write into sysconfig and KICK registers. Does this sound > fine to you? > Shall I resend this patch without omap_rtc_wait_not_busy()? If there's no need for the unlock/lock sequence to ensure that the IP block is completely reset, then there doesn't seem to be much point in including it? - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm/mach-omap2/omap_hwmod.h b/arch/arm/mach-omap2/omap_hwmod.h index 76bce11..649576e 100644 --- a/arch/arm/mach-omap2/omap_hwmod.h +++ b/arch/arm/mach-omap2/omap_hwmod.h @@ -751,6 +751,8 @@ const char *omap_hwmod_get_main_clk(struct omap_hwmod *oh); */ extern int omap_hwmod_aess_preprogram(struct omap_hwmod *oh); +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh); +void omap_hwmod_rtc_lock(struct omap_hwmod *oh); /* * Chip variant-specific hwmod init routines - XXX should be converted diff --git a/arch/arm/mach-omap2/omap_hwmod_reset.c b/arch/arm/mach-omap2/omap_hwmod_reset.c index 65e186c..0e21daa 100644 --- a/arch/arm/mach-omap2/omap_hwmod_reset.c +++ b/arch/arm/mach-omap2/omap_hwmod_reset.c @@ -29,6 +29,16 @@ #include <sound/aess.h> #include "omap_hwmod.h" +#include "common.h" + +#define OMAP_RTC_STATUS_REG 0x44 +#define OMAP_RTC_KICK0_REG 0x6c +#define OMAP_RTC_KICK1_REG 0x70 + +#define OMAP_RTC_KICK0_VALUE 0x83E70B13 +#define OMAP_RTC_KICK1_VALUE 0x95A4F1E0 +#define OMAP_RTC_STATUS_BUSY BIT(0) +#define OMAP_RTC_MAX_READY_TIME 50 /** * omap_hwmod_aess_preprogram - enable AESS internal autogating @@ -51,3 +61,58 @@ int omap_hwmod_aess_preprogram(struct omap_hwmod *oh) return 0; } + +/** + * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag + * @oh: struct omap_hwmod * + * + * For updating certain RTC registers, the MPU must wait + * for the BUSY status in OMAP_RTC_STATUS_REG to become zero. + * Once the BUSY status is zero, there is a 15-?s access + * period in which the MPU can program. + */ +static void omap_rtc_wait_not_busy(struct omap_hwmod *oh) +{ + int i; + + /* BUSY may stay active for 1/32768 second (~30 usec) */ + omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG) + & OMAP_RTC_STATUS_REG, OMAP_RTC_MAX_READY_TIME, i); + /* now we have ~15 usec to read/write various registers */ +} + +/** + * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism. + * @oh: struct omap_hwmod * + * + * RTC IP have kicker feature. This prevents spurious writes to its registers. + * In order to write into any of the RTC registers, KICK values has te be + * written in respective KICK registers. This is needed for hwmod to write into + * sysconfig register. + */ +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh) +{ + local_irq_disable(); + omap_rtc_wait_not_busy(oh); + omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG); + omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG); + local_irq_enable(); +} + +/** + * omap_hwmod_rtc_lock - Lock the Kicker mechanism. + * @oh: struct omap_hwmod * + * + * RTC IP have kicker feature. This prevents spurious writes to its registers. + * Once the RTC registers are written, KICK mechanism needs to be locked, + * in order to prevent any spurious writes. This function locks back the RTC + * registers once hwmod completes its write into sysconfig register. + */ +void omap_hwmod_rtc_lock(struct omap_hwmod *oh) +{ + local_irq_disable(); + omap_rtc_wait_not_busy(oh); + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG); + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG); + local_irq_enable(); +}
RTC IP have kicker feature which prevents spurious writes to its registers. In order to write into any of the RTC registers, KICK values has to be written to KICK registers. Introduce omap_hwmod_rtc_unlock/lock functions, which writes into these KICK registers inorder to lock and unlock RTC registers. Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> --- arch/arm/mach-omap2/omap_hwmod.h | 2 ++ arch/arm/mach-omap2/omap_hwmod_reset.c | 65 ++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+)