char/tpm_tis_i2c: minor bugfixes and cleanups

This patchset consists of minor bugfixes and cleanups to the Infineon
IFX TPM TIS I2C Driver.
These patches were already sent to the TPM Maintainer who is currently
reviewing the driver.

The patchset consists of these patches:

char/tpm: Fix cleanup behavior if no hardware is attached in tpm_tis_i2c.c

This patch fixes the cleanup behavior if no hardware is attached, by fixing the
exit points.

Without this patch the driver fails to release the registered minor number if
no hardware is attached.
Moreover if the driver gets called 256 times without the hardware attached,
tpm_register_hardware runs out of device numbers and consequently fails and
tpm_remove_hardware gets called with a NULL pointer, leading to an OOPS.

char/tpm: spellcheck and version bump for tpm_tis_i2c.c

This patch fixes a small typo and bumps the version of tpm_tis_i2c.c to 2.1.1

char/tpm: workaround: TPM can't handle more than 0x4f9 bytes

If the TPM (beta firmware) receives more than 0x4f9 Bytes the TPM shuts itself
down. Since this is usually not the desired behavior the driver has to workaound
this bug by blocking any input over 0x4f9 (1273) bytes.
We chose 1260 as an (arbitrary) upper limit, just to be on the safe side.

char/tpm: don't bypass timeout mechanism for burstcount

If the tpm keeps on reporting burstcount == 0 the driver gets into an endless
loop. This patch fixes this by removing the bypass of the timeout mechanism for
burstcount.
If burstcount == 0 (for some time) the driver now returns gracefully with a
 -EBUSY.

char/tpm_tis_i2c: Update driver to proposed mainline version

This patch updates the tpm_tis_i2c.c driver to the version that was sent
to the LKML.

The patch fixes some spelling errors and bumps the version to 2.1.0
The patch is needed to apply the upcomming patches cleanly.

Change-Id: I95ca3ea90cc4976d3e4f5f19aa37d3f72e0703c2

BUG=
TEST=Running the trousers testsuite several times, manual tests, IFX LinuxDD testsuite
Signed-off-by: Peter Huewe <huewe.external@infineon.com>
Signed-off-by: Peter Huewe <huewe.external@infineon.com>
Signed-off-by: Peter Huewe <huewe.external@infineon.com>
Signed-off-by: Peter Huewe <huewe.external@infineon.com>
Signed-off-by: Peter Huewe <huewe.external@infineon.com>
Signed-off-by: Olof Johansson <olofj@chromium.org>
Review URL: http://codereview.chromium.org/6794015

diff --git a/drivers/char/tpm/tpm_tis_i2c.c b/drivers/char/tpm/tpm_tis_i2c.c
index a948db9..8696b5f 100644 (file)
--- a/drivers/char/tpm/tpm_tis_i2c.c
+++ b/drivers/char/tpm/tpm_tis_i2c.c
@@ -20,8 +20,8 @@
  * License.
  *
  * NOTE:
- * Suspend does currently not work Nvidias Tegra2 Platform (tested on Seaboard)
- * but works fine on Beagleboard (arm omap).
+ * Suspend does currently not work Nvidias Tegra2 Platform
+ * but works fine on Beagleboard (ARM OMAP).
  *
  */
 #include <linux/init.h>
@@ -31,8 +31,8 @@
 #include <linux/wait.h>
 #include "tpm.h"
 
-/* max. buffer size required by TPM commands/results */
-#define TPM_BUFSIZE 4096
+/* max. buffer size supported by our tpm */
+#define TPM_BUFSIZE 1260
 
 /* max. number of iterations after i2c NAK */
 #define MAX_COUNT 3
@@ -97,7 +97,7 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
        if (rc <= 0)
                return -EIO;
 
-       /* After the TPM has sucessfully received the register address it needs
+       /* After the TPM has successfully received the register address it needs
         * some time, thus we're sleeping here again, before retrieving the data
         */
        for (count = 0; count < MAX_COUNT; count++) {
@@ -324,9 +324,9 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
        while (size < count) {
                burstcnt = get_burstcount(chip);
 
-               /* wait for positive burst count */
-               if (burstcnt <= 0)
-                       continue;
+               /* burstcnt < 0 = tpm is busy */
+               if (burstcnt < 0)
+                       return burstcnt;
 
                /* limit received data to max. left */
                if (burstcnt > (count-size))
@@ -397,6 +397,9 @@ static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
        size_t count = 0;
        u8 sts = TPM_STS_GO;
 
+       if (len > TPM_BUFSIZE)
+               return -E2BIG; /* command is too long for our tpm, sorry */
+
        if (request_locality(chip, 0) < 0)
                return -EBUSY;
 
@@ -417,9 +420,9 @@ static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
                        "send(): count=%zd, len=%zd, burstcount=%d (plain)\n",
                        count, len, burstcnt);
 
-               /* wait for positive burst count */
-               if (burstcnt <= 0)
-                       continue;
+               /* burstcnt < 0 = tpm is busy */
+               if (burstcnt < 0)
+                       return burstcnt;
 
                if (burstcnt > (len-1-count))
                        burstcnt = len-1-count;
@@ -534,7 +537,7 @@ static int tpm_tis_i2c_init(struct device *dev)
 
        if (request_locality(chip, 0) != 0) {
                rc = -ENODEV;
-               goto out_err;
+               goto out_vendor;
        }
 
        /* read four bytes from DID_VID register */
@@ -566,9 +569,9 @@ out_release:
 
 out_vendor:
        tpm_dev_vendor_release(chip);
+       tpm_remove_hardware(chip->dev);
 
 out_err:
-       tpm_remove_hardware(chip->dev);
        return rc;
 }
 
@@ -580,10 +583,12 @@ static const struct i2c_device_id tpm_i2c_tis_table[] = {
 
 #ifdef CONFIG_PM
 /* NOTE:
- * Suspend does currently not work Nvidias Tegra2 Platform (tested on Seaboard)
+ * Suspend does currently not work Nvidias Tegra2 Platform
  * but works fine on Beagleboard (arm omap).
  *
- * This function will block System Suspend if TPM is not initialized.
+ * This function will block System Suspend if TPM is not initialized,
+ * however the TPM is usually initialized by BIOS/u-boot or by sending
+ * a tpm startup command.
  */
 static int tpm_tis_i2c_suspend(struct device *dev)
 {
@@ -708,5 +713,5 @@ module_init(init_tis_i2c);
 module_exit(cleanup_tis_i2c);
 MODULE_AUTHOR("Peter Huewe <huewe.external@infineon.com>");
 MODULE_DESCRIPTION("TPM TIS I2C Driver");
-MODULE_VERSION("2.0.99");
+MODULE_VERSION("2.1.2");
 MODULE_LICENSE("GPL");