tpm: device class for tpm

Added own device class for TPM. Uses MISC_MAJOR:TPM_MINOR for the
first character device in order to retain backwards compatibility.
Added tpm_dev_release() back attached to the character device.

I've been running this code now for a while on my laptop (Lenovo
T430S) TrouSerS works perfectly without modifications. I don't
believe it breaks anything significantly.

The sysfs attributes that have been placed under the wrong place
and are against sysfs-rules.txt should be probably left to
stagnate under platform device directory and start defining
new sysfs attributes to the char device directory.

Guidelines for future TPM sysfs attributes should be probably
along the lines of

- Single flat set of mandatory sysfs attributes. For example,
  current PPI interface is way way too rich when you only want
  to use it to clear and activate the TPM.

- Define sysfs attribute if and only if there's no way to get
  the value from ring-3. No attributes for TPM properties. It's
  just unnecessary maintenance hurdle that we don't want.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jasob Gunthorpe <jason.gunthorpe@obsidianresearch.com>
Reviewed-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Tested-by: Scot Doyle <lkml14@scotdoyle.com>
Tested-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

1 files changed, 62 insertions, 10 deletions

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index e72b042aa867..7596eef3bff9 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -25,6 +25,7 @@
 #include <linux/mutex.h>
 #include <linux/spinlock.h>
 #include <linux/freezer.h>
+#include <linux/major.h>
 #include "tpm.h"
 #include "tpm_eventlog.h"
 
@@ -32,6 +33,9 @@ static DECLARE_BITMAP(dev_mask, TPM_NUM_DEVICES);
 static LIST_HEAD(tpm_chip_list);
 static DEFINE_SPINLOCK(driver_lock);
 
+struct class *tpm_class;
+dev_t tpm_devt;
+
 /*
  * tpm_chip_find_get - return tpm_chip for a given chip number
  * @chip_num the device number for the chip
@@ -55,16 +59,14 @@ struct tpm_chip *tpm_chip_find_get(int chip_num)
 }
 
 /**
- * tpmm_chip_remove() - free chip memory and device number
- * @data: points to struct tpm_chip instance
+ * tpm_dev_release() - free chip memory and the device number
+ * @dev: the character device for the TPM chip
  *
- * This is used internally by tpmm_chip_alloc() and called by devres
- * when the device is released. This function does the opposite of
- * tpmm_chip_alloc() freeing memory and the device number.
+ * This is used as the release function for the character device.
  */
-static void tpmm_chip_remove(void *data)
+static void tpm_dev_release(struct device *dev)
 {
-	struct tpm_chip *chip = (struct tpm_chip *) data;
+	struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
 
 	spin_lock(&driver_lock);
 	clear_bit(chip->dev_num, dev_mask);
@@ -111,18 +113,68 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev,
 	scnprintf(chip->devname, sizeof(chip->devname), "tpm%d", chip->dev_num);
 
 	chip->pdev = dev;
-	devm_add_action(dev, tpmm_chip_remove, chip);
+
 	dev_set_drvdata(dev, chip);
 
+	chip->dev.class = tpm_class;
+	chip->dev.release = tpm_dev_release;
+	chip->dev.parent = chip->pdev;
+
+	if (chip->dev_num == 0)
+		chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
+	else
+		chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num);
+
+	dev_set_name(&chip->dev, chip->devname);
+
+	device_initialize(&chip->dev);
+
+	chip->cdev.owner = chip->pdev->driver->owner;
+	cdev_init(&chip->cdev, &tpm_fops);
+
 	return chip;
 }
 EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
 
+static int tpm_dev_add_device(struct tpm_chip *chip)
+{
+	int rc;
+
+	rc = device_add(&chip->dev);
+	if (rc) {
+		dev_err(&chip->dev,
+			"unable to device_register() %s, major %d, minor %d, err=%d\n",
+			chip->devname, MAJOR(chip->dev.devt),
+			MINOR(chip->dev.devt), rc);
+
+		return rc;
+	}
+
+	rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
+	if (rc) {
+		dev_err(&chip->dev,
+			"unable to cdev_add() %s, major %d, minor %d, err=%d\n",
+			chip->devname, MAJOR(chip->dev.devt),
+			MINOR(chip->dev.devt), rc);
+
+		device_unregister(&chip->dev);
+		return rc;
+	}
+
+	return rc;
+}
+
+static void tpm_dev_del_device(struct tpm_chip *chip)
+{
+	cdev_del(&chip->cdev);
+	device_unregister(&chip->dev);
+}
+
 /*
- * tpm_chip_register() - create a misc driver for the TPM chip
+ * tpm_chip_register() - create a character device for the TPM chip
  * @chip: TPM chip to use.
  *
- * Creates a misc driver for the TPM chip and adds sysfs interfaces for
+ * Creates a character device for the TPM chip and adds sysfs interfaces for
  * the device, PPI and TCPA. As the last step this function adds the
  * chip to the list of TPM chips available for use.
  *