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Date: Thu, 2 Mar 2023 21:55:18 +0000
From: "Limonciello, Mario" <Mario.Limonciello@....com>
To: "Lendacky, Thomas" <Thomas.Lendacky@....com>,
Jan Dąbroś <jsd@...ihalf.com>,
Grzegorz Bernacki <gjb@...ihalf.com>,
"Thomas, Rijo-john" <Rijo-john.Thomas@....com>,
"herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
"Allen, John" <John.Allen@....com>
CC: "David S. Miller" <davem@...emloft.net>,
"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 7/9] crypto: ccp: Add support for ringing a platform
doorbell
[Public]
> -----Original Message-----
> From: Lendacky, Thomas <Thomas.Lendacky@....com>
> Sent: Thursday, March 2, 2023 15:52
> To: Limonciello, Mario <Mario.Limonciello@....com>; Jan Dąbroś
> <jsd@...ihalf.com>; Grzegorz Bernacki <gjb@...ihalf.com>; Thomas, Rijo-
> john <Rijo-john.Thomas@....com>; herbert@...dor.apana.org.au; Allen,
> John <John.Allen@....com>
> Cc: David S. Miller <davem@...emloft.net>; linux-crypto@...r.kernel.org;
> linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v2 7/9] crypto: ccp: Add support for ringing a platform
> doorbell
>
> On 3/2/23 13:42, Mario Limonciello wrote:
> > Some platforms support using a doorbell to communicate. Export
> > this feature for other drivers to utilize as well.
> >
> > Link: https://lore.kernel.org/linux-i2c/20220916131854.687371-3-
> jsd@...ihalf.com/
> > Suggested-by: Jan Dabros <jsd@...ihalf.com>
> > Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> > ---
> > v1->v2:
> > * New patch
> > ---
> > drivers/crypto/ccp/platform-access.c | 47
> ++++++++++++++++++++++++++++
> > drivers/crypto/ccp/sp-dev.h | 1 +
> > include/linux/psp-platform-access.h | 15 +++++++++
> > include/linux/psp.h | 3 ++
> > 4 files changed, 66 insertions(+)
> >
> > diff --git a/drivers/crypto/ccp/platform-access.c
> b/drivers/crypto/ccp/platform-access.c
> > index af3a1e97abfe..0763389a2814 100644
> > --- a/drivers/crypto/ccp/platform-access.c
> > +++ b/drivers/crypto/ccp/platform-access.c
> > @@ -135,6 +135,53 @@ int psp_send_platform_access_msg(enum
> psp_platform_access_msg msg,
> > }
> > EXPORT_SYMBOL_GPL(psp_send_platform_access_msg);
> >
> > +int psp_ring_platform_doorbell(enum psp_platform_access_msg msg)
> > +{
> > + struct psp_device *psp = psp_get_master_device();
> > + struct psp_platform_access_device *pa_dev;
> > + u32 __iomem *drbl;
> > + u32 drbl_reg;
>
> Lets spell out doorbell for these two variable names.
Ack. Given drbl_reg is only used one place, I might just drop it too.
>
> > + int ret;
> > +
> > + if (!psp || !psp->platform_access_data)
> > + return -ENODEV;
> > +
> > + pa_dev = psp->platform_access_data;
> > + drbl = psp->io_regs + pa_dev->vdata->doorbell_reg;
> > +
> > + if (!drbl)
> > + return -ENODEV;
>
> This will be non-zero because psp->io_regs will always be non-zero. Maybe
> you meant to check the actual pa_dev->vdata->doorbell_reg value?
>
> I think you should squash this and patch #9 together so that patch #8 just
> works right away.
Ack, I'll squash them together.
>
> > +
> > + mutex_lock(&pa_dev->mutex);
>
> Does the doorbell register operate independently from the other registers
> (C2PMSG_28 - C2PMSG_30)? If it does, you could probably just introduce a
> doorbell mutex.
It does work independently. I'll add a second mutex.
>
> > +
> > + if (check_recovery(drbl)) {
> > + dev_dbg(psp->dev, "in recovery\n");
>
> Maybe a bit more info as to what is "in recovery" (that goes for patch #4,
> too) or just prefix it with "doorbell" (and "platform" in #4) since you
> now have duplicated messages.
Will add prefixes to make unique messages.
>
> > + ret = -EBUSY;
> > + goto unlock;
> > + }
> > +
> > + if (wait_cmd(drbl)) {
> > + dev_dbg(psp->dev, "not done processing command\n");
>
> Ditto.
>
> Thanks,
> Tom
Thanks for the new comments.
I'll wait on Jan and Grzegorz to confirm whether the new doorbell stuff works
on Skyrim or not to spin a v3.
>
> > + ret = -EBUSY;
> > + goto unlock;
> > + }
> > +
> > + drbl_reg = FIELD_PREP(PSP_DRBL_MSG, msg) | PSP_DRBL_RING;
> > + iowrite32(drbl_reg, drbl);
> > +
> > + if (wait_cmd(drbl)) {
> > + ret = -ETIMEDOUT;
> > + goto unlock;
> > + }
> > +
> > + ret = 0;
> > +unlock:
> > + mutex_unlock(&pa_dev->mutex);
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(psp_ring_platform_doorbell);
> > +
> > void platform_access_dev_destroy(struct psp_device *psp)
> > {
> > struct psp_platform_access_device *pa_dev = psp-
> >platform_access_data;
> > diff --git a/drivers/crypto/ccp/sp-dev.h b/drivers/crypto/ccp/sp-dev.h
> > index 5ec6c219a731..87c0b9350bc2 100644
> > --- a/drivers/crypto/ccp/sp-dev.h
> > +++ b/drivers/crypto/ccp/sp-dev.h
> > @@ -54,6 +54,7 @@ struct tee_vdata {
> > };
> >
> > struct platform_access_vdata {
> > + const unsigned int doorbell_reg;
> > const unsigned int cmdresp_reg;
> > const unsigned int cmdbuff_addr_lo_reg;
> > const unsigned int cmdbuff_addr_hi_reg;
> > diff --git a/include/linux/psp-platform-access.h b/include/linux/psp-
> platform-access.h
> > index f5a03cd11f10..1e1d0e077cec 100644
> > --- a/include/linux/psp-platform-access.h
> > +++ b/include/linux/psp-platform-access.h
> > @@ -35,6 +35,21 @@ struct psp_request {
> > */
> > int psp_send_platform_access_msg(enum psp_platform_access_msg,
> struct psp_request *req);
> >
> > +/**
> > + * psp_ring_platform_doorbell() - Ring platform doorbell
> > + *
> > + * This function is intended to be used by drivers outside of ccp to ring the
> > + * platform doorbell with a message.
> > + *
> > + * Returns:
> > + * 0: success
> > + * -%EBUSY: mailbox in recovery or in use
> > + * -%ENODEV: driver not bound with PSP device
> > + * -%ETIMEDOUT: request timed out
> > + * -%EIO: unknown error (see kernel log)
> > + */
> > +int psp_ring_platform_doorbell(enum psp_platform_access_msg);
> > +
> > /**
> > * psp_check_platform_access_status() - Checks whether platform
> features is ready
> > *
> > diff --git a/include/linux/psp.h b/include/linux/psp.h
> > index d3424790a70e..92e60aeef21e 100644
> > --- a/include/linux/psp.h
> > +++ b/include/linux/psp.h
> > @@ -23,4 +23,7 @@
> > #define PSP_CMDRESP_RECOVERY BIT(30)
> > #define PSP_CMDRESP_RESP BIT(31)
> >
> > +#define PSP_DRBL_MSG PSP_CMDRESP_CMD
> > +#define PSP_DRBL_RING BIT(0)
> > +
> > #endif /* __PSP_H */
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