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Date: Tue, 14 Jun 2016 16:14:58 +0300
From: Tomas Winkler <tomasw@...il.com>
To: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc: Peter Huewe <peterhuewe@....de>,
open list <linux-kernel@...r.kernel.org>,
linux-security-module@...r.kernel.org,
"moderated list:TPM DEVICE DRIVER"
<tpmdd-devel@...ts.sourceforge.net>
Subject: Re: [tpmdd-devel] [PATCH 3/3] tpm, tpm_crb: runtime power management
On Wed, Jun 8, 2016 at 2:02 AM, Jarkko Sakkinen
<jarkko.sakkinen@...ux.intel.com> wrote:
> The register TPM_CRB_CTRL_REQ_0 contains bits goIdle and cmdReady for
> invoking the chip to suspend and resume. This commit implements runtime
> PM for tpm_crb by using these bits.
>
> The legacy ACPI start (SMI + DMA) based devices do not support these
> bits. Thus this functionality only is enabled only for CRB start (MMIO)
> based devices.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> ---
> drivers/char/tpm/tpm-interface.c | 3 ++
> drivers/char/tpm/tpm_crb.c | 62 ++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 63 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 5e3c1b6..3b85648 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -29,6 +29,7 @@
> #include <linux/mutex.h>
> #include <linux/spinlock.h>
> #include <linux/freezer.h>
> +#include <linux/pm_runtime.h>
>
> #include "tpm.h"
> #include "tpm_eventlog.h"
> @@ -350,6 +351,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
> return -E2BIG;
> }
>
> + pm_runtime_get_sync(chip->dev.parent);
> mutex_lock(&chip->tpm_mutex);
>
> rc = chip->ops->send(chip, (u8 *) buf, count);
> @@ -394,6 +396,7 @@ out_recv:
> "tpm_transmit: tpm_recv: error %zd\n", rc);
> out:
> mutex_unlock(&chip->tpm_mutex);
> + pm_runtime_put_sync(chip->dev.parent);
> return rc;
> }
>
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index ca2cad9..71cc7cd 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -20,6 +20,7 @@
> #include <linux/rculist.h>
> #include <linux/module.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> #include "tpm.h"
>
> #define ACPI_SIG_TPM2 "TPM2"
> @@ -41,7 +42,6 @@ enum crb_ca_request {
>
> enum crb_ca_status {
> CRB_CA_STS_ERROR = BIT(0),
> - CRB_CA_STS_TPM_IDLE = BIT(1),
> };
>
> enum crb_start {
> @@ -68,6 +68,8 @@ struct crb_control_area {
>
> enum crb_status {
> CRB_STS_COMPLETE = BIT(0),
> + CRB_STS_READY = BIT(1),
> + CRB_STS_IDLE = BIT(2),
> };
>
> enum crb_flags {
> @@ -81,9 +83,52 @@ struct crb_priv {
> struct crb_control_area __iomem *cca;
> u8 __iomem *cmd;
> u8 __iomem *rsp;
> + wait_queue_head_t idle_queue;
I'm failing to find the code that is calling wake_up_interruptible(idle_queue);
> };
>
> -static SIMPLE_DEV_PM_OPS(crb_pm, tpm_pm_suspend, tpm_pm_resume);
> +static int __maybe_unused crb_runtime_suspend(struct device *dev)
> +{
> + struct tpm_chip *chip = dev_get_drvdata(dev);
> + struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> + u32 req;
> +
> + if (priv->flags & CRB_FL_ACPI_START)
> + return 0;
> +
> + req = ioread32(&priv->cca->req);
> +
> + iowrite32(cpu_to_le32(req | CRB_CA_REQ_GO_IDLE), &priv->cca->req);
> +
> + if (wait_for_tpm_stat(chip, CRB_STS_IDLE, chip->timeout_c,
> + &priv->idle_queue, false))
> + dev_warn(&chip->dev, "idle timed out\n");
Unfortunately you cannot do that as there is an HW errata, the status
register value might not be defined here during power transition
You should poll for request CRB_CA_REQ_GO_IDLE goes to 0 as descried
in the spec . only after that you can check for the status register
(thought it's maybe not needed)
> +
> + return 0;
> +}
> +
> +static int __maybe_unused crb_runtime_resume(struct device *dev)
why this is marked unused, why just not compile it out? if the
CONFIG_PM is not set?
> +{
> + struct tpm_chip *chip = dev_get_drvdata(dev);
> + struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> + u32 req;
> +
> + if (priv->flags & CRB_FL_ACPI_START)
> + return 0;
> +
> + req = ioread32(&priv->cca->req);
> + iowrite32(cpu_to_le32(req | CRB_CA_REQ_CMD_READY), &priv->cca->req);
> +
> + if (wait_for_tpm_stat(chip, CRB_STS_READY, chip->timeout_c,
> + &priv->idle_queue, false))
> + dev_warn(&chip->dev, "wake timed out\n");
Same here, you should wait for CRB_CA_REQ_CMD_READ to get cleared,
only after that it is safe to check the status register.
> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops crb_pm = {
> + SET_RUNTIME_PM_OPS(crb_runtime_suspend, crb_runtime_resume, NULL)
> + SET_SYSTEM_SLEEP_PM_OPS(tpm_pm_suspend, tpm_pm_resume)
> +};
>
> static u8 crb_status(struct tpm_chip *chip)
> {
> @@ -94,6 +139,14 @@ static u8 crb_status(struct tpm_chip *chip)
> CRB_START_INVOKE)
> sts |= CRB_STS_COMPLETE;
>
> + if ((ioread32(&priv->cca->req) & CRB_CA_REQ_CMD_READY) !=
> + CRB_CA_REQ_CMD_READY)
> + sts |= CRB_STS_READY;
There is meaning for checking this w/o the actual transition i.e.
setting the before
> + if ((ioread32(&priv->cca->req) & CRB_CA_REQ_GO_IDLE) !=
> + CRB_CA_REQ_GO_IDLE)
> + sts |= CRB_STS_IDLE;
Same here.
> +
> return sts;
> }
>
> @@ -206,6 +259,8 @@ static int crb_init(struct acpi_device *device, struct crb_priv *priv)
> if (IS_ERR(chip))
> return PTR_ERR(chip);
>
> + pm_runtime_set_active(&device->dev);
> + pm_runtime_enable(&device->dev);
> dev_set_drvdata(&chip->dev, priv);
> chip->acpi_dev_handle = device->handle;
> chip->flags = TPM_CHIP_FLAG_TPM2;
> @@ -348,6 +403,8 @@ static int crb_acpi_add(struct acpi_device *device)
> !strcmp(acpi_device_hid(device), "MSFT0101"))
> priv->flags |= CRB_FL_CRB_START;
>
> + init_waitqueue_head(&priv->idle_queue);
> +
> if (sm == ACPI_TPM2_START_METHOD ||
> sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> priv->flags |= CRB_FL_ACPI_START;
> @@ -366,6 +423,7 @@ static int crb_acpi_remove(struct acpi_device *device)
>
> tpm_chip_unregister(chip);
>
> + pm_runtime_disable(dev);
> return 0;
> }
>
Thanks
Tomas
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