diff mbox series

[v9,08/12] tpm, tpm: Implement usage counter for locality

Message ID 20221110152533.24243-9-LinoSanfilippo@gmx.de (mailing list archive)
State New
Headers show
Series TPM IRQ fixes | expand

Commit Message

Lino Sanfilippo Nov. 10, 2022, 3:25 p.m. UTC
From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Implement a usage counter for the (default) locality used by the TPM TIS
driver:
Request the locality from the TPM if it has not been claimed yet, otherwise
only increment the counter. Also release the locality if the counter is 0
otherwise only decrement the counter. Since in case of SPI the register
accesses are locked by means of the SPI bus mutex use a sleepable lock
(i.e. also a mutex) to ensure thread-safety of the counter which may be
accessed by both a userspace thread and the interrupt handler.

By doing this refactor the names of the amended functions to use a more
appropriate prefix.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Tested-by: Michael Niewöhner <linux@mniewoehner.de>
---
 drivers/char/tpm/tpm_tis_core.c | 75 ++++++++++++++++++++++-----------
 drivers/char/tpm/tpm_tis_core.h |  2 +
 2 files changed, 53 insertions(+), 24 deletions(-)
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 4336f7ea8c2b..ecde684a8f80 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -165,16 +165,27 @@  static bool check_locality(struct tpm_chip *chip, int l)
 	return false;
 }
 
-static int release_locality(struct tpm_chip *chip, int l)
+static int __tpm_tis_relinquish_locality(struct tpm_tis_data *priv, int l)
+{
+	tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
+
+	return 0;
+}
+
+static int tpm_tis_relinquish_locality(struct tpm_chip *chip, int l)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 
-	tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
+	mutex_lock(&priv->locality_count_mutex);
+	priv->locality_count--;
+	if (priv->locality_count == 0)
+		__tpm_tis_relinquish_locality(priv, l);
+	mutex_unlock(&priv->locality_count_mutex);
 
 	return 0;
 }
 
-static int request_locality(struct tpm_chip *chip, int l)
+static int __tpm_tis_request_locality(struct tpm_chip *chip, int l)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 	unsigned long stop, timeout;
@@ -215,6 +226,20 @@  static int request_locality(struct tpm_chip *chip, int l)
 	return -1;
 }
 
+static int tpm_tis_request_locality(struct tpm_chip *chip, int l)
+{
+	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+	int ret = 0;
+
+	mutex_lock(&priv->locality_count_mutex);
+	if (priv->locality_count == 0)
+		ret = __tpm_tis_request_locality(chip, l);
+	if (!ret)
+		priv->locality_count++;
+	mutex_unlock(&priv->locality_count_mutex);
+	return ret;
+}
+
 static u8 tpm_tis_status(struct tpm_chip *chip)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
@@ -682,7 +707,7 @@  static int probe_itpm(struct tpm_chip *chip)
 	if (vendor != TPM_VID_INTEL)
 		return 0;
 
-	if (request_locality(chip, 0) != 0)
+	if (tpm_tis_request_locality(chip, 0) != 0)
 		return -EBUSY;
 
 	rc = tpm_tis_send_data(chip, cmd_getticks, len);
@@ -703,7 +728,7 @@  static int probe_itpm(struct tpm_chip *chip)
 
 out:
 	tpm_tis_ready(chip);
-	release_locality(chip, priv->locality);
+	tpm_tis_relinquish_locality(chip, priv->locality);
 
 	return rc;
 }
@@ -762,7 +787,7 @@  static int tpm_tis_gen_interrupt(struct tpm_chip *chip)
 	cap_t cap;
 	int ret;
 
-	ret = request_locality(chip, 0);
+	ret = tpm_tis_request_locality(chip, 0);
 	if (ret < 0)
 		return ret;
 
@@ -771,7 +796,7 @@  static int tpm_tis_gen_interrupt(struct tpm_chip *chip)
 	else
 		ret = tpm1_getcap(chip, TPM_CAP_PROP_TIS_TIMEOUT, &cap, desc, 0);
 
-	release_locality(chip, 0);
+	tpm_tis_relinquish_locality(chip, 0);
 
 	return ret;
 }
@@ -796,33 +821,33 @@  static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
 	}
 	priv->irq = irq;
 
-	rc = request_locality(chip, 0);
+	rc = tpm_tis_request_locality(chip, 0);
 	if (rc < 0)
 		return rc;
 
 	rc = tpm_tis_read8(priv, TPM_INT_VECTOR(priv->locality),
 			   &original_int_vec);
 	if (rc < 0) {
-		release_locality(chip, priv->locality);
+		tpm_tis_relinquish_locality(chip, priv->locality);
 		return rc;
 	}
 
 	rc = tpm_tis_write8(priv, TPM_INT_VECTOR(priv->locality), irq);
 	if (rc < 0) {
-		release_locality(chip, priv->locality);
+		tpm_tis_relinquish_locality(chip, priv->locality);
 		return rc;
 	}
 
 	rc = tpm_tis_read32(priv, TPM_INT_STATUS(priv->locality), &int_status);
 	if (rc < 0) {
-		release_locality(chip, priv->locality);
+		tpm_tis_relinquish_locality(chip, priv->locality);
 		return rc;
 	}
 
 	/* Clear all existing */
 	rc = tpm_tis_write32(priv, TPM_INT_STATUS(priv->locality), int_status);
 	if (rc < 0) {
-		release_locality(chip, priv->locality);
+		tpm_tis_relinquish_locality(chip, priv->locality);
 		return rc;
 	}
 
@@ -830,11 +855,11 @@  static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
 	rc = tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality),
 			     intmask | TPM_GLOBAL_INT_ENABLE);
 	if (rc < 0) {
-		release_locality(chip, priv->locality);
+		tpm_tis_relinquish_locality(chip, priv->locality);
 		return rc;
 	}
 
-	release_locality(chip, priv->locality);
+	tpm_tis_relinquish_locality(chip, priv->locality);
 	clear_bit(TPM_TIS_IRQ_TESTED, &priv->flags);
 
 	/* Generate an interrupt by having the core call through to
@@ -970,8 +995,8 @@  static const struct tpm_class_ops tpm_tis = {
 	.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 	.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
 	.req_canceled = tpm_tis_req_canceled,
-	.request_locality = request_locality,
-	.relinquish_locality = release_locality,
+	.request_locality = tpm_tis_request_locality,
+	.relinquish_locality = tpm_tis_relinquish_locality,
 	.clk_enable = tpm_tis_clkrun_enable,
 };
 
@@ -1005,6 +1030,8 @@  int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 	priv->timeout_min = TPM_TIMEOUT_USECS_MIN;
 	priv->timeout_max = TPM_TIMEOUT_USECS_MAX;
 	priv->phy_ops = phy_ops;
+	priv->locality_count = 0;
+	mutex_init(&priv->locality_count_mutex);
 
 	dev_set_drvdata(&chip->dev, priv);
 
@@ -1083,14 +1110,14 @@  int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 
 	intmask &= ~TPM_GLOBAL_INT_ENABLE;
 
-	rc = request_locality(chip, 0);
+	rc = tpm_tis_request_locality(chip, 0);
 	if (rc < 0) {
 		rc = -ENODEV;
 		goto out_err;
 	}
 
 	tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
-	release_locality(chip, 0);
+	tpm_tis_relinquish_locality(chip, 0);
 
 	rc = tpm_chip_start(chip);
 	if (rc)
@@ -1124,13 +1151,13 @@  int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 		 * proper timeouts for the driver.
 		 */
 
-		rc = request_locality(chip, 0);
+		rc = tpm_tis_request_locality(chip, 0);
 		if (rc < 0)
 			goto out_err;
 
 		rc = tpm_get_timeouts(chip);
 
-		release_locality(chip, 0);
+		tpm_tis_relinquish_locality(chip, 0);
 
 		if (rc) {
 			dev_err(dev, "Could not get TPM timeouts and durations\n");
@@ -1150,11 +1177,11 @@  int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 			dev_err(&chip->dev, FW_BUG
 					"TPM interrupt not working, polling instead\n");
 
-			rc = request_locality(chip, 0);
+			rc = tpm_tis_request_locality(chip, 0);
 			if (rc < 0)
 				goto out_err;
 			disable_interrupts(chip);
-			release_locality(chip, 0);
+			tpm_tis_relinquish_locality(chip, 0);
 		}
 	}
 
@@ -1221,13 +1248,13 @@  int tpm_tis_resume(struct device *dev)
 	 * an error code but for unknown reason it isn't handled.
 	 */
 	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
-		ret = request_locality(chip, 0);
+		ret = tpm_tis_request_locality(chip, 0);
 		if (ret < 0)
 			return ret;
 
 		tpm1_do_selftest(chip);
 
-		release_locality(chip, 0);
+		tpm_tis_relinquish_locality(chip, 0);
 	}
 
 	return 0;
diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index 2deef11c88db..13bdcf38e56f 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -91,6 +91,8 @@  enum tpm_tis_flags {
 
 struct tpm_tis_data {
 	u16 manufacturer_id;
+	struct mutex locality_count_mutex;
+	unsigned int locality_count;
 	int locality;
 	int irq;
 	unsigned int int_mask;