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Subject[PATCH] char/tpm: use msleep(), clean-up timers, fix typo
On Wed, Mar 09, 2005 at 04:42:01PM -0800, Greg KH wrote:
> ChangeSet 1.2035, 2005/03/09 10:12:19-08:00, kjhall@us.ibm.com
>
> [PATCH] Add TPM hardware enablement driver
>
> This patch is a device driver to enable new hardware. The new hardware is
> the TPM chip as described by specifications at
> <http://www.trustedcomputinggroup.org>. The TPM chip will enable you to
> use hardware to securely store and protect your keys and personal data.
> To use the chip according to the specification, you will need the Trusted
> Software Stack (TSS) of which an implementation for Linux is available at:
> <http://sourceforge.net/projects/trousers>.

Here is a patch that removes all callers of schedule_timeout() as I
previously mentioned:

Description: The TPM driver unnecessarily uses timers when it simply
needs to maintain a maximum delay via time_before(). msleep() is used
instead of schedule_timeout() to guarantee the task delays as expected.
While compile-testing, I found a typo in the driver, using tpm_chp
instead of tpm_chip. Remove the now unused timer callback function and
change TPM_TIMEOUT's units to milliseconds. Patch is compile-tested.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>

diff -urpN 2.6.11-v/drivers/char/tpm/tpm.c 2.6.11/drivers/char/tpm/tpm.c
--- 2.6.11-v/drivers/char/tpm/tpm.c 2005-03-10 10:50:00.000000000 -0800
+++ 2.6.11/drivers/char/tpm/tpm.c 2005-03-10 11:00:50.000000000 -0800
@@ -19,7 +19,7 @@
*
* Note, the TPM chip is not interrupt driven (only polling)
* and can have very long timeouts (minutes!). Hence the unusual
- * calls to schedule_timeout.
+ * calls to msleep.
*
*/

@@ -52,14 +52,6 @@ static void user_reader_timeout(unsigned
up(&chip->buffer_mutex);
}

-void tpm_time_expired(unsigned long ptr)
-{
- int *exp = (int *) ptr;
- *exp = 1;
-}
-
-EXPORT_SYMBOL_GPL(tpm_time_expired);
-
/*
* Initialize the LPC bus and enable the TPM ports
*/
@@ -135,6 +127,7 @@ static ssize_t tpm_transmit(struct tpm_c
ssize_t len;
u32 count;
__be32 *native_size;
+ unsigned long stop;

native_size = (__force __be32 *) (buf + 2);
count = be32_to_cpu(*native_size);
@@ -155,28 +148,16 @@ static ssize_t tpm_transmit(struct tpm_c
return len;
}

- down(&chip->timer_manipulation_mutex);
- chip->time_expired = 0;
- init_timer(&chip->device_timer);
- chip->device_timer.function = tpm_time_expired;
- chip->device_timer.expires = jiffies + 2 * 60 * HZ;
- chip->device_timer.data = (unsigned long) &chip->time_expired;
- add_timer(&chip->device_timer);
- up(&chip->timer_manipulation_mutex);
-
+ stop = jiffies + 2 * 60 * HZ;
do {
u8 status = inb(chip->vendor->base + 1);
if ((status & chip->vendor->req_complete_mask) ==
chip->vendor->req_complete_val) {
- down(&chip->timer_manipulation_mutex);
- del_singleshot_timer_sync(&chip->device_timer);
- up(&chip->timer_manipulation_mutex);
goto out_recv;
}
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(TPM_TIMEOUT);
+ msleep(TPM_TIMEOUT); /* CHECK */
rmb();
- } while (!chip->time_expired);
+ } while (time_before(jiffies, stop));


chip->vendor->cancel(chip);
@@ -219,7 +200,7 @@ static ssize_t show_pcrs(struct device *
int i, j, index, num_pcrs;
char *str = buf;

- struct tpm_chp *chip =
+ struct tpm_chip *chip =
pci_get_drvdata(container_of(dev, struct pci_dev, dev));
if (chip == NULL)
return -ENODEV;
@@ -450,10 +431,8 @@ ssize_t tpm_write(struct file * file, co

/* cannot perform a write until the read has cleared
either via tpm_read or a user_read_timer timeout */
- while (atomic_read(&chip->data_pending) != 0) {
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(TPM_TIMEOUT);
- }
+ while (atomic_read(&chip->data_pending) != 0)
+ msleep(TPM_TIMEOUT);

down(&chip->buffer_mutex);

diff -urpN 2.6.11-v/drivers/char/tpm/tpm.h 2.6.11/drivers/char/tpm/tpm.h
--- 2.6.11-v/drivers/char/tpm/tpm.h 2005-03-10 10:50:00.000000000 -0800
+++ 2.6.11/drivers/char/tpm/tpm.h 2005-03-10 10:58:12.000000000 -0800
@@ -24,7 +24,7 @@
#include <linux/delay.h>
#include <linux/miscdevice.h>

-#define TPM_TIMEOUT msecs_to_jiffies(5)
+#define TPM_TIMEOUT 5 /* msecs */

/* TPM addresses */
#define TPM_ADDR 0x4E
@@ -77,7 +77,6 @@ static inline void tpm_write_index(int i
outb(value & 0xFF, TPM_DATA);
}

-extern void tpm_time_expired(unsigned long);
extern int tpm_lpc_bus_init(struct pci_dev *, u16);

extern int tpm_register_hardware(struct pci_dev *,
diff -urpN 2.6.11-v/drivers/char/tpm/tpm_nsc.c 2.6.11/drivers/char/tpm/tpm_nsc.c
--- 2.6.11-v/drivers/char/tpm/tpm_nsc.c 2005-03-10 10:50:00.000000000 -0800
+++ 2.6.11/drivers/char/tpm/tpm_nsc.c 2005-03-10 10:56:54.000000000 -0800
@@ -55,10 +55,7 @@
*/
static int wait_for_stat(struct tpm_chip *chip, u8 mask, u8 val, u8 * data)
{
- int expired = 0;
- struct timer_list status_timer =
- TIMER_INITIALIZER(tpm_time_expired, jiffies + 10 * HZ,
- (unsigned long) &expired);
+ unsigned long stop;

/* status immediately available check */
*data = inb(chip->vendor->base + NSC_STATUS);
@@ -66,17 +63,14 @@ static int wait_for_stat(struct tpm_chip
return 0;

/* wait for status */
- add_timer(&status_timer);
+ stop = jiffies + 10 * HZ;
do {
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(TPM_TIMEOUT);
+ msleep(TPM_TIMEOUT);
*data = inb(chip->vendor->base + 1);
- if ((*data & mask) == val) {
- del_singleshot_timer_sync(&status_timer);
+ if ((*data & mask) == val)
return 0;
- }
}
- while (!expired);
+ while (time_before(jiffies, stop));

return -EBUSY;
}
@@ -84,10 +78,7 @@ static int wait_for_stat(struct tpm_chip
static int nsc_wait_for_ready(struct tpm_chip *chip)
{
int status;
- int expired = 0;
- struct timer_list status_timer =
- TIMER_INITIALIZER(tpm_time_expired, jiffies + 100,
- (unsigned long) &expired);
+ unsigned long stop;

/* status immediately available check */
status = inb(chip->vendor->base + NSC_STATUS);
@@ -97,19 +88,16 @@ static int nsc_wait_for_ready(struct tpm
return 0;

/* wait for status */
- add_timer(&status_timer);
+ stop = jiffies + 100;
do {
- set_current_state(TASK_UNINTERRUPTIBLE);
- schedule_timeout(TPM_TIMEOUT);
+ msleep(TPM_TIMEOUT);
status = inb(chip->vendor->base + NSC_STATUS);
if (status & NSC_STATUS_OBF)
status = inb(chip->vendor->base + NSC_DATA);
- if (status & NSC_STATUS_RDY) {
- del_singleshot_timer_sync(&status_timer);
+ if (status & NSC_STATUS_RDY)
return 0;
- }
}
- while (!expired);
+ while (time_before(jiffies, stop));

dev_info(&chip->pci_dev->dev, "wait for ready failed\n");
return -EBUSY;
-
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