[PATCH] char/tpm: use msleep(), clean-up timers, fix typo

[Nishanth Aravamudan <nacc@us.ibm.com>]

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;