From: khilman@linaro•org (Kevin Hilman)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv3 8/9] ARM: OMAP2+: AM33XX: Basic suspend resume support
Date: Thu, 29 Aug 2013 15:02:47 -0700 [thread overview]
Message-ID: <87y57krw8o.fsf@linaro.org> (raw)
In-Reply-To: <521FC000.6080900@ti.com> (Dave Gerlach's message of "Thu, 29 Aug 2013 16:41:20 -0500")
Dave Gerlach <d-gerlach@ti•com> writes:
> On 08/27/2013 04:45 PM, Kevin Hilman wrote:
>> Dave Gerlach <d-gerlach@ti•com> writes:
>>
>>> From: Vaibhav Bedia <vaibhav.bedia@ti•com>
>>>
>>> AM335x supports various low power modes as documented
>>> in section 8.1.4.3 of the AM335x TRM which is available
>>> @ http://www.ti.com/litv/pdf/spruh73f
>>>
>>> DeepSleep0 mode offers the lowest power mode with limited
>>> wakeup sources without a system reboot and is mapped as
>>> the suspend state in the kernel. In this state, MPU and
>>> PER domains are turned off with the internal RAM held in
>>> retention to facilitate resume process. As part of the boot
>>> process, the assembly code is copied over to OCMCRAM using
>>> the OMAP SRAM code.
>>>
>>> AM335x has a Cortex-M3 (WKUP_M3) which assists the MPU
>>> in DeepSleep0 entry and exit. WKUP_M3 takes care of the
>>> clockdomain and powerdomain transitions based on the
>>> intended low power state. MPU needs to load the appropriate
>>> WKUP_M3 binary onto the WKUP_M3 memory space before it can
>>> leverage any of the PM features like DeepSleep.
>>>
>>> The IPC mechanism between MPU and WKUP_M3 uses a mailbox
>>> sub-module and 8 IPC registers in the Control module. MPU
>>> uses the assigned Mailbox for issuing an interrupt to
>>> WKUP_M3 which then goes and checks the IPC registers for
>>> the payload. WKUP_M3 has the ability to trigger on interrupt
>>
>> s/trigger on interrupt/trigger an interrupt/ ??
>
> Oops I will fix that.
>
>>
>>> to MPU by executing the "sev" instruction.
>>>
>>> In the current implementation when the suspend process
>>> is initiated MPU interrupts the WKUP_M3 to let it know about
>>> the intent of entering DeepSleep0 and waits for an ACK. When
>>> the ACK is received MPU continues with its suspend process
>>> to suspend all the drivers and then jumps to assembly in
>>> OCMC RAM. The assembly code puts the PLLs in bypass, puts the
>>> external RAM in self-refresh mode and then finally execute the
>>> WFI instruction. Execution of the WFI instruction triggers another
>>> interrupt to the WKUP_M3 which then continues wiht the power down
>>> sequence wherein the clockdomain and powerdomain transition takes
>>> place. As part of the sleep sequence, WKUP_M3 unmasks the interrupt
>>> lines for the wakeup sources. WFI execution on WKUP_M3 causes the
>>> hardware to disable the main oscillator of the SoC.
>>>
>>> When a wakeup event occurs, WKUP_M3 starts the power-up
>>> sequence by switching on the power domains and finally
>>> enabling the clock to MPU. Since the MPU gets powered down
>>> as part of the sleep sequence in the resume path ROM code
>>> starts executing. The ROM code detects a wakeup from sleep
>>> and then jumps to the resume location in OCMC which was
>>> populated in one of the IPC registers as part of the suspend
>>> sequence.
>>>
>>> The low level code in OCMC relocks the PLLs, enables access
>>> to external RAM and then jumps to the cpu_resume code of
>>> the kernel to finish the resume process.
>>
>> [...]
>>
>>> arch/arm/mach-omap2/pm33xx.c | 474 +++++++++++++++++++++++++++++++++++++++++
>>> arch/arm/mach-omap2/pm33xx.h | 77 +++++++
>>> arch/arm/mach-omap2/wkup_m3.c | 183 ++++++++++++++++
>>
>>
>> Looking closer at this code as I'm trying to fully get my head around
>> all the IPC, I have some more comments.
>>
>> I think the split between pm33xx.c and the M3 driver is still confusing
>> here. For example, am33xx_ping_wkup_m3(),
>> am33xx_m3_state_machine_reset() and the guts of am33xx_pm_begin() all
>> belong inside the M3 driver, along with all the wakeup_src stuff, which
>> is info coming from the M3.
>>
>> IOW, the communication with M3 should be abstracted from pm33xx by the
>> M3 driver (or possibly an eventual remoteproc/rpmsg implementation) with
>> a well defined API. In this implementation, the interface is pretty
>> fuzzy and mixed between pm33xx.c and wkup_m3.c.
>
> I have since moved much more of the m3 functionality, including the
> ping and wakeup src code, into the wkup_m3 driver to make the split
> more clear but I haven't yet moved the state machine portion into the
> wkup_m3 driver. I feel that this is the portion of the IPC that could
> potentially be the most variant between different SoC implementations
> so leaving this in the pm code should allow for more flexibility.
I still think this belogs in the M3 driver, because AFAICT, it's
specific to the M3 firmware, not to the SoC.
>>
>> Kevin
>>
>> P.S. I'd also suggest renaming wakeup_src to something else since
>> it's close to wakeup_source which has a rather different meaning in the
>> kernel (c.f. linux/pm_wakeup.h)
>>
>
> I will rename this to tie it into the M3 code.
Great, thanks.
Kevin
next prev parent reply other threads:[~2013-08-29 22:02 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-06 17:49 [PATCHv3 0/9] ARM: OMAP2+: AM33XX: Add suspend-resume support Dave Gerlach
2013-08-06 17:49 ` [PATCHv3 1/9] memory: emif: Move EMIF register defines to include/linux/ Dave Gerlach
2013-08-08 0:48 ` Russ Dill
2013-08-08 13:35 ` Santosh Shilimkar
2013-08-12 19:32 ` Greg Kroah-Hartman
2013-08-12 19:33 ` Santosh Shilimkar
2013-08-06 17:49 ` [PATCHv3 2/9] ARM: OMAP2+: AM33XX: control: Add some control module registers and APIs Dave Gerlach
2013-08-08 0:52 ` Russ Dill
2013-08-08 13:44 ` Santosh Shilimkar
2013-08-08 16:16 ` Dave Gerlach
2013-08-09 5:11 ` Tony Lindgren
2013-08-09 20:55 ` Dave Gerlach
2013-08-12 7:54 ` Tony Lindgren
2013-08-12 19:17 ` Kevin Hilman
2013-08-12 21:40 ` Dave Gerlach
2013-08-13 14:29 ` Kevin Hilman
2013-08-13 15:08 ` Santosh Shilimkar
2013-08-13 16:19 ` Kevin Hilman
2013-08-13 18:18 ` Santosh Shilimkar
2013-08-13 18:30 ` Russ Dill
2013-08-13 18:40 ` Santosh Shilimkar
2013-08-13 19:11 ` Kevin Hilman
2013-08-14 17:27 ` Suman Anna
2013-08-14 19:16 ` Russ Dill
2013-08-20 23:39 ` Paul Walmsley
2013-08-21 17:32 ` Suman Anna
2013-08-06 17:49 ` [PATCHv3 3/9] ARM: OMAP: DTB: Update IRQ data for WKUP_M3 Dave Gerlach
2013-08-08 0:53 ` Russ Dill
2013-08-08 13:46 ` Santosh Shilimkar
2013-08-06 17:49 ` [PATCHv3 4/9] ARM: OMAP2+: AM33XX: Reserve memory to comply with EMIF spec Dave Gerlach
2013-08-08 2:30 ` Russ Dill
2013-08-08 14:19 ` Santosh Shilimkar
2013-08-08 18:16 ` Kevin Hilman
2013-08-08 19:31 ` Santosh Shilimkar
2013-08-08 20:05 ` Kevin Hilman
2013-08-08 20:11 ` Santosh Shilimkar
2013-08-09 15:11 ` Kevin Hilman
2013-08-09 16:25 ` Dave Gerlach
2013-08-06 17:49 ` [PATCHv3 5/9] ARM: OMAP2+: AM33XX: Add assembly code for PM operations Dave Gerlach
2013-08-08 7:02 ` Russ Dill
2013-08-08 14:50 ` Santosh Shilimkar
2013-08-08 15:16 ` Russ Dill
2013-08-08 15:22 ` Santosh Shilimkar
2013-08-08 16:03 ` Russ Dill
2013-08-19 12:54 ` Gururaja Hebbar
2013-08-19 17:51 ` Dave Gerlach
2013-08-06 17:49 ` [PATCHv3 6/9] ARM: OMAP2+: timer: Add suspend-resume callbacks for clkevent device Dave Gerlach
2013-08-08 7:03 ` Russ Dill
2013-08-08 14:23 ` Santosh Shilimkar
2013-08-08 16:09 ` Dave Gerlach
2013-08-08 18:25 ` Kevin Hilman
2013-08-08 19:49 ` Dave Gerlach
2013-08-06 17:49 ` [PATCHv3 7/9] ARM: OMAP: omap_device: Add APIs to enable and idle hwmods Dave Gerlach
2013-08-08 7:05 ` Russ Dill
2013-08-08 14:26 ` Santosh Shilimkar
2013-08-06 17:49 ` [PATCHv3 8/9] ARM: OMAP2+: AM33XX: Basic suspend resume support Dave Gerlach
2013-08-07 16:22 ` Nishanth Menon
2013-08-07 18:12 ` Dave Gerlach
2013-08-07 19:16 ` Nishanth Menon
2013-08-08 8:45 ` Russ Dill
2013-08-08 12:26 ` Nishanth Menon
2013-08-08 15:03 ` Santosh Shilimkar
2013-08-08 16:06 ` Dave Gerlach
2013-08-08 16:22 ` Nishanth Menon
2013-08-08 21:14 ` Kevin Hilman
2013-08-08 21:32 ` Nishanth Menon
2013-08-08 23:04 ` Kevin Hilman
2013-08-09 15:11 ` Nishanth Menon
2013-08-09 16:12 ` Kevin Hilman
2013-08-09 16:36 ` Nishanth Menon
2013-08-09 20:34 ` Kevin Hilman
2013-08-09 21:35 ` Nishanth Menon
2013-08-09 22:28 ` Russ Dill
2013-08-12 16:09 ` Kevin Hilman
2013-08-30 17:29 ` Vaibhav Bedia
2013-08-20 22:48 ` Paul Walmsley
2013-08-23 14:56 ` Dave Gerlach
2013-08-13 7:43 ` Russ Dill
2013-08-13 14:59 ` Kevin Hilman
2013-08-27 21:45 ` Kevin Hilman
2013-08-29 21:41 ` Dave Gerlach
2013-08-29 22:02 ` Kevin Hilman [this message]
2013-08-30 17:39 ` Vaibhav Bedia
2013-08-30 21:18 ` Kevin Hilman
2013-08-06 17:49 ` [PATCHv3 9/9] ARM: OMAP2+: AM33XX: Hookup AM33XX PM code into OMAP builds Dave Gerlach
2013-08-08 8:47 ` Russ Dill
2013-08-08 14:53 ` Santosh Shilimkar
2013-08-08 13:31 ` [PATCHv3 0/9] ARM: OMAP2+: AM33XX: Add suspend-resume support Santosh Shilimkar
2013-08-11 11:53 ` Daniel Mack
2013-08-12 18:59 ` Dave Gerlach
2013-08-13 12:39 ` Daniel Mack
2013-08-13 15:33 ` Dave Gerlach
2013-08-13 15:51 ` Daniel Mack
2013-08-19 9:23 ` Gururaja Hebbar
2013-08-19 17:47 ` Dave Gerlach
2013-08-27 20:23 ` Kevin Hilman
2013-08-29 21:30 ` Dave Gerlach
2013-08-29 21:52 ` Kevin Hilman
2013-08-29 22:20 ` Dave Gerlach
2013-08-29 22:20 ` Kevin Hilman
2013-08-29 22:43 ` Russ Dill
2013-08-29 23:02 ` Kevin Hilman
2013-09-03 17:24 ` Dave Gerlach
2013-09-04 15:01 ` Kevin Hilman
2013-09-04 15:12 ` Russ Dill
2013-09-04 15:18 ` Kevin Hilman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87y57krw8o.fsf@linaro.org \
--to=khilman@linaro$(echo .)org \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox