diff mbox series

[2/3] char: tpm: cr50: Use generic request/relinquish locality ops

Message ID 20221101020352.939691-3-jsd@semihalf.com (mailing list archive)
State New, archived
Headers show
Series char: tpm: Adjust cr50_i2c locking mechanism | expand

Commit Message

Jan Dąbroś Nov. 1, 2022, 2:03 a.m. UTC 
Instead of using static functions tpm_cr50_request_locality and
tpm_cr50_release_locality register callbacks from tpm class chip->ops
created for this purpose.

Signed-off-by: Jan Dabros <jsd@semihalf.com>
---
 drivers/char/tpm/tpm_tis_i2c_cr50.c | 98 ++++++++++++++++++-----------
 1 file changed, 60 insertions(+), 38 deletions(-)

Comments

Tim Van Patten Nov. 1, 2022, 4:04 p.m. UTC | #1 
On Mon, Oct 31, 2022 at 8:04 PM Jan Dabros <jsd@semihalf.com> wrote:
>  /**
> - * tpm_cr50_check_locality() - Verify TPM locality 0 is active.
> + * tpm_cr50_check_locality() - Verify if required TPM locality is active.
>   * @chip: A TPM chip.
> + * @loc: Locality to be verified
>   *
>   * Return:
> - * - 0:                Success.
> + * - loc:      Success.
>   * - -errno:   A POSIX error code.
>   */
> -static int tpm_cr50_check_locality(struct tpm_chip *chip)
> +static int tpm_cr50_check_locality(struct tpm_chip *chip, int loc)
>  {
>         u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY;
>         u8 buf;
>         int rc;
>
> -       rc = tpm_cr50_i2c_read(chip, TPM_I2C_ACCESS(0), &buf, sizeof(buf));
> +       rc = tpm_cr50_i2c_read(chip, TPM_I2C_ACCESS(loc), &buf, sizeof(buf));
>         if (rc < 0)
>                 return rc;
>
>         if ((buf & mask) == mask)
> -               return 0;
> +               return loc;
>
>         return -EIO;
>  }

Why is it useful to return the same `loc` value that was passed in,
rather than just returning `0`? The caller already knows the value of
`loc`, so they aren't being told anything new.

I think this should continue to return `0` for success.


> - * tpm_cr50_request_locality() - Request TPM locality 0.
> + * tpm_cr50_request_locality() - Request TPM locality.
>   * @chip: A TPM chip.
> + * @loc: Locality to be requested.
>   *
>   * Return:
> - * - 0:                Success.
> + * - loc:      Success.

Same as above. Return `0`.

> @@ -374,7 +386,9 @@ static u8 tpm_cr50_i2c_tis_status(struct tpm_chip *chip)
>  {
>         u8 buf[4];
>
> -       if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(0), buf, sizeof(buf)) < 0)
> +       WARN_ONCE((chip->locality < 0), "Incorrect tpm locality value\n");

For each of these ` WARN_ONCE((chip->locality < 0), ...).`, can it
return immediately rather than attempting to continue using an invalid
locality value? Do the following commands have a chance of succeeding
with the invalid value?
Jan Dąbroś Nov. 2, 2022, 9:42 p.m. UTC | #2 
> >  /**
> > - * tpm_cr50_check_locality() - Verify TPM locality 0 is active.
> > + * tpm_cr50_check_locality() - Verify if required TPM locality is active.
> >   * @chip: A TPM chip.
> > + * @loc: Locality to be verified
> >   *
> >   * Return:
> > - * - 0:                Success.
> > + * - loc:      Success.
> >   * - -errno:   A POSIX error code.
> >   */
> > -static int tpm_cr50_check_locality(struct tpm_chip *chip)
> > +static int tpm_cr50_check_locality(struct tpm_chip *chip, int loc)
> >  {
> >         u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY;
> >         u8 buf;
> >         int rc;
> >
> > -       rc = tpm_cr50_i2c_read(chip, TPM_I2C_ACCESS(0), &buf, sizeof(buf));
> > +       rc = tpm_cr50_i2c_read(chip, TPM_I2C_ACCESS(loc), &buf, sizeof(buf));
> >         if (rc < 0)
> >                 return rc;
> >
> >         if ((buf & mask) == mask)
> > -               return 0;
> > +               return loc;
> >
> >         return -EIO;
> >  }
>
> Why is it useful to return the same `loc` value that was passed in,
> rather than just returning `0`? The caller already knows the value of
> `loc`, so they aren't being told anything new.
>
> I think this should continue to return `0` for success.

I agree, I should keep this as it was.

>
>
> > - * tpm_cr50_request_locality() - Request TPM locality 0.
> > + * tpm_cr50_request_locality() - Request TPM locality.
> >   * @chip: A TPM chip.
> > + * @loc: Locality to be requested.
> >   *
> >   * Return:
> > - * - 0:                Success.
> > + * - loc:      Success.
>
> Same as above. Return `0`.

The case here is that .request_locality callback should return active
locality. This value is assigned to chip->locality inside
tpm_request_locality() [drivers/char/tpm/tpm-chip.c].

>
> > @@ -374,7 +386,9 @@ static u8 tpm_cr50_i2c_tis_status(struct tpm_chip *chip)
> >  {
> >         u8 buf[4];
> >
> > -       if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(0), buf, sizeof(buf)) < 0)
> > +       WARN_ONCE((chip->locality < 0), "Incorrect tpm locality value\n");
>
> For each of these ` WARN_ONCE((chip->locality < 0), ...).`, can it
> return immediately rather than attempting to continue using an invalid
> locality value? Do the following commands have a chance of succeeding
> with the invalid value?

I agree - it makes more sense to return immediately instead of trying
to send invalid configuration over i2c.

Best Regards,
Jan
Grzegorz Bernacki Sept. 30, 2024, 11:52 a.m. UTC | #3 
Tim,

[...]
> Why is it useful to return the same `loc` value that was passed in,
> rather than just returning `0`? The caller already knows the value of
> `loc`, so they aren't being told anything new.
> 
> I think this should continue to return `0` for success.

I think Jan just followed the conventions, when he returned 'loc' instead of
'0', some others request/release locality function do exactly the same.

[...]
> For each of these ` WARN_ONCE((chip->locality < 0), ...).`, can it
> return immediately rather than attempting to continue using an invalid
> locality value? Do the following commands have a chance of succeeding
> with the invalid value?

WARN_ONCE() macro does not remove checking of locality. If I understand
the code correctly layer above should not called this function if
request locality fails, so this code is an extra check. 
I can remove it in the next patchset if you want.

Jarkko,

Would it be possible to merge this changes. Patch 1. has already been merged,
only 2 and 3 are still waiting. Do you want me to create a new patchset for
these two patches?

thanks,
greg
Jarkko Sakkinen Oct. 7, 2024, 11:37 p.m. UTC | #4 
On Mon, 2024-09-30 at 11:52 +0000, bernacki@chromium.org wrote:
> Tim,
> 
> [...]
> > Why is it useful to return the same `loc` value that was passed in,
> > rather than just returning `0`? The caller already knows the value
> > of
> > `loc`, so they aren't being told anything new.
> > 
> > I think this should continue to return `0` for success.
> 
> I think Jan just followed the conventions, when he returned 'loc'
> instead of
> '0', some others request/release locality function do exactly the
> same.
> 
> [...]
> > For each of these ` WARN_ONCE((chip->locality < 0), ...).`, can it
> > return immediately rather than attempting to continue using an
> > invalid
> > locality value? Do the following commands have a chance of
> > succeeding
> > with the invalid value?
> 
> WARN_ONCE() macro does not remove checking of locality. If I
> understand
> the code correctly layer above should not called this function if
> request locality fails, so this code is an extra check. 
> I can remove it in the next patchset if you want.
> 
> Jarkko,
> 
> Would it be possible to merge this changes. Patch 1. has already been
> merged,
> only 2 and 3 are still waiting. Do you want me to create a new
> patchset for
> these two patches?

Send a rebased version that applies. Let's check that through
then. Quick recap and some time gone, I don't see anything
extremely bad. Still acking patches that even do not apply
is not possible.

So yeah, send. If glitches are spotted in worst case this
means two rounds.

> 
> thanks,
> greg


BR, Jarkko
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm_tis_i2c_cr50.c b/drivers/char/tpm/tpm_tis_i2c_cr50.c
index 77cea5b31c6e4..d3438a4ed1ef8 100644
--- a/drivers/char/tpm/tpm_tis_i2c_cr50.c
+++ b/drivers/char/tpm/tpm_tis_i2c_cr50.c
@@ -17,6 +17,7 @@ 
  */
 
 #include <linux/acpi.h>
+#include <linux/bug.h>
 #include <linux/completion.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
@@ -35,6 +36,7 @@ 
 #define TPM_CR50_I2C_MAX_RETRIES	3		/* Max retries due to I2C errors */
 #define TPM_CR50_I2C_RETRY_DELAY_LO	55		/* Min usecs between retries on I2C */
 #define TPM_CR50_I2C_RETRY_DELAY_HI	65		/* Max usecs between retries on I2C */
+#define TPM_CR50_I2C_DEFAULT_LOC	0
 
 #define TPM_I2C_ACCESS(l)	(0x0000 | ((l) << 4))
 #define TPM_I2C_STS(l)		(0x0001 | ((l) << 4))
@@ -286,25 +288,26 @@  static int tpm_cr50_i2c_write(struct tpm_chip *chip, u8 addr, u8 *buffer,
 }
 
 /**
- * tpm_cr50_check_locality() - Verify TPM locality 0 is active.
+ * tpm_cr50_check_locality() - Verify if required TPM locality is active.
  * @chip: A TPM chip.
+ * @loc: Locality to be verified
  *
  * Return:
- * - 0:		Success.
+ * - loc:	Success.
  * - -errno:	A POSIX error code.
  */
-static int tpm_cr50_check_locality(struct tpm_chip *chip)
+static int tpm_cr50_check_locality(struct tpm_chip *chip, int loc)
 {
 	u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY;
 	u8 buf;
 	int rc;
 
-	rc = tpm_cr50_i2c_read(chip, TPM_I2C_ACCESS(0), &buf, sizeof(buf));
+	rc = tpm_cr50_i2c_read(chip, TPM_I2C_ACCESS(loc), &buf, sizeof(buf));
 	if (rc < 0)
 		return rc;
 
 	if ((buf & mask) == mask)
-		return 0;
+		return loc;
 
 	return -EIO;
 }
@@ -312,48 +315,57 @@  static int tpm_cr50_check_locality(struct tpm_chip *chip)
 /**
  * tpm_cr50_release_locality() - Release TPM locality.
  * @chip:	A TPM chip.
- * @force:	Flag to force release if set.
+ * @loc:	Locality to be released
+ *
+ * Return:
+ * - 0:		Success.
+ * - -errno:	A POSIX error code.
  */
-static void tpm_cr50_release_locality(struct tpm_chip *chip, bool force)
+static int tpm_cr50_release_locality(struct tpm_chip *chip, int loc)
 {
 	u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_REQUEST_PENDING;
-	u8 addr = TPM_I2C_ACCESS(0);
+	u8 addr = TPM_I2C_ACCESS(loc);
 	u8 buf;
+	int rc;
 
-	if (tpm_cr50_i2c_read(chip, addr, &buf, sizeof(buf)) < 0)
-		return;
+	rc = tpm_cr50_i2c_read(chip, addr, &buf, sizeof(buf));
+	if (rc < 0)
+		return rc;
 
-	if (force || (buf & mask) == mask) {
+	if ((buf & mask) == mask) {
 		buf = TPM_ACCESS_ACTIVE_LOCALITY;
-		tpm_cr50_i2c_write(chip, addr, &buf, sizeof(buf));
+		rc = tpm_cr50_i2c_write(chip, addr, &buf, sizeof(buf));
 	}
+
+	return rc;
 }
 
 /**
- * tpm_cr50_request_locality() - Request TPM locality 0.
+ * tpm_cr50_request_locality() - Request TPM locality.
  * @chip: A TPM chip.
+ * @loc: Locality to be requested.
  *
  * Return:
- * - 0:		Success.
+ * - loc:	Success.
  * - -errno:	A POSIX error code.
  */
-static int tpm_cr50_request_locality(struct tpm_chip *chip)
+static int tpm_cr50_request_locality(struct tpm_chip *chip, int loc)
 {
 	u8 buf = TPM_ACCESS_REQUEST_USE;
 	unsigned long stop;
 	int rc;
 
-	if (!tpm_cr50_check_locality(chip))
-		return 0;
+	if (tpm_cr50_check_locality(chip, loc) == loc)
+		return loc;
 
-	rc = tpm_cr50_i2c_write(chip, TPM_I2C_ACCESS(0), &buf, sizeof(buf));
+	rc = tpm_cr50_i2c_write(chip, TPM_I2C_ACCESS(loc), &buf, sizeof(buf));
 	if (rc < 0)
 		return rc;
 
 	stop = jiffies + chip->timeout_a;
 	do {
-		if (!tpm_cr50_check_locality(chip))
-			return 0;
+		if (tpm_cr50_check_locality(chip, loc) == loc)
+			return loc;
 
 		msleep(TPM_CR50_TIMEOUT_SHORT_MS);
 	} while (time_before(jiffies, stop));
@@ -374,7 +386,9 @@  static u8 tpm_cr50_i2c_tis_status(struct tpm_chip *chip)
 {
 	u8 buf[4];
 
-	if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(0), buf, sizeof(buf)) < 0)
+	WARN_ONCE((chip->locality < 0), "Incorrect tpm locality value\n");
+
+	if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(chip->locality), buf, sizeof(buf)) < 0)
 		return 0;
 
 	return buf[0];
@@ -390,7 +404,9 @@  static void tpm_cr50_i2c_tis_set_ready(struct tpm_chip *chip)
 {
 	u8 buf[4] = { TPM_STS_COMMAND_READY };
 
-	tpm_cr50_i2c_write(chip, TPM_I2C_STS(0), buf, sizeof(buf));
+	WARN_ONCE((chip->locality < 0), "Incorrect tpm locality value\n");
+
+	tpm_cr50_i2c_write(chip, TPM_I2C_STS(chip->locality), buf, sizeof(buf));
 	msleep(TPM_CR50_TIMEOUT_SHORT_MS);
 }
 
@@ -420,7 +436,7 @@  static int tpm_cr50_i2c_get_burst_and_status(struct tpm_chip *chip, u8 mask,
 	stop = jiffies + chip->timeout_b;
 
 	do {
-		if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(0), buf, sizeof(buf)) < 0) {
+		if (tpm_cr50_i2c_read(chip, TPM_I2C_STS(chip->locality), buf, sizeof(buf)) < 0) {
 			msleep(TPM_CR50_TIMEOUT_SHORT_MS);
 			continue;
 		}
@@ -454,10 +470,12 @@  static int tpm_cr50_i2c_tis_recv(struct tpm_chip *chip, u8 *buf, size_t buf_len)
 
 	u8 mask = TPM_STS_VALID | TPM_STS_DATA_AVAIL;
 	size_t burstcnt, cur, len, expected;
-	u8 addr = TPM_I2C_DATA_FIFO(0);
+	u8 addr = TPM_I2C_DATA_FIFO(chip->locality);
 	u32 status;
 	int rc;
 
+	WARN_ONCE((chip->locality < 0), "Incorrect tpm locality value\n");
+
 	if (buf_len < TPM_HEADER_SIZE)
 		return -EINVAL;
 
@@ -516,7 +534,6 @@  static int tpm_cr50_i2c_tis_recv(struct tpm_chip *chip, u8 *buf, size_t buf_len)
 		goto out_err;
 	}
 
-	tpm_cr50_release_locality(chip, false);
 	return cur;
 
 out_err:
@@ -524,7 +541,6 @@  static int tpm_cr50_i2c_tis_recv(struct tpm_chip *chip, u8 *buf, size_t buf_len)
 	if (tpm_cr50_i2c_tis_status(chip) & TPM_STS_COMMAND_READY)
 		tpm_cr50_i2c_tis_set_ready(chip);
 
-	tpm_cr50_release_locality(chip, false);
 	return rc;
 }
 
@@ -546,9 +562,7 @@  static int tpm_cr50_i2c_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	u32 status;
 	int rc;
 
-	rc = tpm_cr50_request_locality(chip);
-	if (rc < 0)
-		return rc;
+	WARN_ONCE((chip->locality < 0), "Incorrect tpm locality value\n");
 
 	/* Wait until TPM is ready for a command */
 	stop = jiffies + chip->timeout_b;
@@ -578,7 +592,8 @@  static int tpm_cr50_i2c_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
 		 * that is inserted by tpm_cr50_i2c_write()
 		 */
 		limit = min_t(size_t, burstcnt - 1, len);
-		rc = tpm_cr50_i2c_write(chip, TPM_I2C_DATA_FIFO(0), &buf[sent], limit);
+		rc = tpm_cr50_i2c_write(chip, TPM_I2C_DATA_FIFO(chip->locality),
+					&buf[sent], limit);
 		if (rc < 0) {
 			dev_err(&chip->dev, "Write failed\n");
 			goto out_err;
@@ -599,7 +614,7 @@  static int tpm_cr50_i2c_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	}
 
 	/* Start the TPM command */
-	rc = tpm_cr50_i2c_write(chip, TPM_I2C_STS(0), tpm_go,
+	rc = tpm_cr50_i2c_write(chip, TPM_I2C_STS(chip->locality), tpm_go,
 				sizeof(tpm_go));
 	if (rc < 0) {
 		dev_err(&chip->dev, "Start command failed\n");
@@ -612,7 +627,6 @@  static int tpm_cr50_i2c_tis_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	if (tpm_cr50_i2c_tis_status(chip) & TPM_STS_COMMAND_READY)
 		tpm_cr50_i2c_tis_set_ready(chip);
 
-	tpm_cr50_release_locality(chip, false);
 	return rc;
 }
 
@@ -651,6 +665,8 @@  static const struct tpm_class_ops cr50_i2c = {
 	.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 	.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 	.req_canceled = &tpm_cr50_i2c_req_canceled,
+	.request_locality = &tpm_cr50_request_locality,
+	.relinquish_locality = &tpm_cr50_release_locality,
 };
 
 #ifdef CONFIG_ACPI
@@ -686,6 +702,7 @@  static int tpm_cr50_i2c_probe(struct i2c_client *client)
 	u32 vendor;
 	u8 buf[4];
 	int rc;
+	int loc;
 
 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -ENODEV;
@@ -728,24 +745,30 @@  static int tpm_cr50_i2c_probe(struct i2c_client *client)
 			 TPM_CR50_TIMEOUT_NOIRQ_MS);
 	}
 
-	rc = tpm_cr50_request_locality(chip);
-	if (rc < 0) {
+	loc = tpm_cr50_request_locality(chip, TPM_CR50_I2C_DEFAULT_LOC);
+	if (loc < 0) {
 		dev_err(dev, "Could not request locality\n");
 		return rc;
 	}
 
 	/* Read four bytes from DID_VID register */
-	rc = tpm_cr50_i2c_read(chip, TPM_I2C_DID_VID(0), buf, sizeof(buf));
+	rc = tpm_cr50_i2c_read(chip, TPM_I2C_DID_VID(loc), buf, sizeof(buf));
 	if (rc < 0) {
 		dev_err(dev, "Could not read vendor id\n");
-		tpm_cr50_release_locality(chip, true);
+		if (tpm_cr50_release_locality(chip, loc))
+			dev_err(dev, "Could not release locality\n");
+		return rc;
+	}
+
+	rc = tpm_cr50_release_locality(chip, loc);
+	if (rc) {
+		dev_err(dev, "Could not release locality\n");
 		return rc;
 	}
 
 	vendor = le32_to_cpup((__le32 *)buf);
 	if (vendor != TPM_CR50_I2C_DID_VID && vendor != TPM_TI50_I2C_DID_VID) {
 		dev_err(dev, "Vendor ID did not match! ID was %08x\n", vendor);
-		tpm_cr50_release_locality(chip, true);
 		return -ENODEV;
 	}
 
@@ -774,7 +797,6 @@  static void tpm_cr50_i2c_remove(struct i2c_client *client)
 	}
 
 	tpm_chip_unregister(chip);
-	tpm_cr50_release_locality(chip, true);
 }
 
 static SIMPLE_DEV_PM_OPS(cr50_i2c_pm, tpm_pm_suspend, tpm_pm_resume);