tpm: two-phase chip management functions

tpm_register_hardware() and tpm_remove_hardware() are called often
before initializing the device. The problem is that the device might
not be fully initialized when it comes visible to the user space.

This patch resolves the issue by diving initialization into two
parts:

- tpmm_chip_alloc() creates struct tpm_chip.

- tpm_chip_register() sets up the character device and sysfs
  attributes.

The framework takes care of freeing struct tpm_chip by using the devres
API. The broken release callback has been wiped. ACPI drivers do not
ever get this callback.

Regards to Jason Gunthorpe for carefully reviewing this part of the
code.

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>
[phuewe: update to upstream changes]
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>

1 files changed, 199 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
new file mode 100644
index 000000000000..7dc9999e2d54
--- /dev/null
+++ b/drivers/char/tpm/tpm-chip.c
@@ -0,0 +1,199 @@
+/*
+ * Copyright (C) 2004 IBM Corporation
+ * Copyright (C) 2014 Intel Corporation
+ *
+ * Authors:
+ * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
+ * Leendert van Doorn <leendert@watson.ibm.com>
+ * Dave Safford <safford@watson.ibm.com>
+ * Reiner Sailer <sailer@watson.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.com>
+ *
+ * Maintained by: <tpmdd-devel@lists.sourceforge.net>
+ *
+ * TPM chip management routines.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/freezer.h>
+#include "tpm.h"
+#include "tpm_eventlog.h"
+
+static DECLARE_BITMAP(dev_mask, TPM_NUM_DEVICES);
+static LIST_HEAD(tpm_chip_list);
+static DEFINE_SPINLOCK(driver_lock);
+
+/*
+ * tpm_chip_find_get - return tpm_chip for a given chip number
+ * @chip_num the device number for the chip
+ */
+struct tpm_chip *tpm_chip_find_get(int chip_num)
+{
+	struct tpm_chip *pos, *chip = NULL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(pos, &tpm_chip_list, list) {
+		if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num)
+			continue;
+
+		if (try_module_get(pos->dev->driver->owner)) {
+			chip = pos;
+			break;
+		}
+	}
+	rcu_read_unlock();
+	return chip;
+}
+
+/**
+ * tpmm_chip_remove() - free chip memory and device number
+ * @data: points to struct tpm_chip instance
+ *
+ * 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.
+ */
+static void tpmm_chip_remove(void *data)
+{
+	struct tpm_chip *chip = (struct tpm_chip *) data;
+
+	spin_lock(&driver_lock);
+	clear_bit(chip->dev_num, dev_mask);
+	spin_unlock(&driver_lock);
+	kfree(chip);
+}
+
+/**
+ * tpmm_chip_alloc() - allocate a new struct tpm_chip instance
+ * @dev: device to which the chip is associated
+ * @ops: struct tpm_class_ops instance
+ *
+ * Allocates a new struct tpm_chip instance and assigns a free
+ * device number for it. Caller does not have to worry about
+ * freeing the allocated resources. When the devices is removed
+ * devres calls tpmm_chip_remove() to do the job.
+ */
+struct tpm_chip *tpmm_chip_alloc(struct device *dev,
+				 const struct tpm_class_ops *ops)
+{
+	struct tpm_chip *chip;
+
+	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&chip->tpm_mutex);
+	INIT_LIST_HEAD(&chip->list);
+
+	chip->ops = ops;
+
+	spin_lock(&driver_lock);
+	chip->dev_num = find_first_zero_bit(dev_mask, TPM_NUM_DEVICES);
+	spin_unlock(&driver_lock);
+
+	if (chip->dev_num >= TPM_NUM_DEVICES) {
+		dev_err(dev, "No available tpm device numbers\n");
+		kfree(chip);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	set_bit(chip->dev_num, dev_mask);
+
+	scnprintf(chip->devname, sizeof(chip->devname), "tpm%d", chip->dev_num);
+
+	chip->dev = dev;
+	devm_add_action(dev, tpmm_chip_remove, chip);
+	dev_set_drvdata(dev, chip);
+
+	return chip;
+}
+EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
+
+/*
+ * tpm_chip_register() - create a misc driver for the TPM chip
+ * @chip: TPM chip to use.
+ *
+ * Creates a misc driver 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.
+ *
+ * NOTE: This function should be only called after the chip initialization
+ * is complete.
+ *
+ * Called from tpm_<specific>.c probe function only for devices
+ * the driver has determined it should claim.  Prior to calling
+ * this function the specific probe function has called pci_enable_device
+ * upon errant exit from this function specific probe function should call
+ * pci_disable_device
+ */
+int tpm_chip_register(struct tpm_chip *chip)
+{
+	int rc;
+
+	rc = tpm_dev_add_device(chip);
+	if (rc)
+		return rc;
+
+	rc = tpm_sysfs_add_device(chip);
+	if (rc)
+		goto del_misc;
+
+	rc = tpm_add_ppi(&chip->dev->kobj);
+	if (rc)
+		goto del_sysfs;
+
+	chip->bios_dir = tpm_bios_log_setup(chip->devname);
+
+	/* Make the chip available. */
+	spin_lock(&driver_lock);
+	list_add_rcu(&chip->list, &tpm_chip_list);
+	spin_unlock(&driver_lock);
+
+	chip->flags |= TPM_CHIP_FLAG_REGISTERED;
+
+	return 0;
+del_sysfs:
+	tpm_sysfs_del_device(chip);
+del_misc:
+	tpm_dev_del_device(chip);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(tpm_chip_register);
+
+/*
+ * tpm_chip_unregister() - release the TPM driver
+ * @chip: TPM chip to use.
+ *
+ * Takes the chip first away from the list of available TPM chips and then
+ * cleans up all the resources reserved by tpm_chip_register().
+ *
+ * NOTE: This function should be only called before deinitializing chip
+ * resources.
+ */
+void tpm_chip_unregister(struct tpm_chip *chip)
+{
+	if (!(chip->flags & TPM_CHIP_FLAG_REGISTERED))
+		return;
+
+	spin_lock(&driver_lock);
+	list_del_rcu(&chip->list);
+	spin_unlock(&driver_lock);
+	synchronize_rcu();
+
+	if (chip->bios_dir)
+		tpm_bios_log_teardown(chip->bios_dir);
+	tpm_remove_ppi(&chip->dev->kobj);
+	tpm_sysfs_del_device(chip);
+
+	tpm_dev_del_device(chip);
+}
+EXPORT_SYMBOL_GPL(tpm_chip_unregister);