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SubjectRe: [PATCH v2 7/9] crypto: ccp: Add support for ringing a platform doorbell
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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@semihalf.com/
> Suggested-by: Jan Dabros <jsd@semihalf.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.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.

> + 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.

> +
> + 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.

> +
> + 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.

> + ret = -EBUSY;
> + goto unlock;
> + }
> +
> + if (wait_cmd(drbl)) {
> + dev_dbg(psp->dev, "not done processing command\n");

Ditto.

Thanks,
Tom

> + 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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