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authorKeith Short <keithshort@chromium.org>2018-12-17 14:21:46 -0700
committerPatrick Georgi <pgeorgi@google.com>2019-01-24 13:52:43 +0000
commit514363541fd1f78cc786a0c1f8d5f047f3baebc7 (patch)
treeed1f496bf106c33d3f1385524eef1c938dc2ae18 /src
parentfc707892de7319cca3dc83e03034e443b2c9f9bb (diff)
downloadcoreboot-514363541fd1f78cc786a0c1f8d5f047f3baebc7.tar.xz
cr50: Add probe command to poll Cr50 until DID VID is valid
Added new routine cr50_i2c_probe() which ensures that communication with the Cr50 over I2C is good prior to attempting other initialization of the Cr50 and TPM state. This avoids a race condition when the Cr50 is first booting that it may reset it's I2C slave interface during the first few I2C transactions initiated from coreboot. BUG=b:120009037 BRANCH=none TEST=Run the Cr50 factory update against Careena board. Confirm that I2C reads are retried until the DID VID is valid. Tested against debug Cr50 firmware that forced failure of cr50_i2c_probe() and verfied that coreboot shows recovery screen. Change-Id: I47c59a32378ad00336277e111e81ba8d2d63e69a Signed-off-by: Keith Short <keithshort@chromium.org> Reviewed-on: https://review.coreboot.org/c/30295 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Raul Rangel <rrangel@chromium.org> Reviewed-by: Martin Roth <martinroth@google.com> Reviewed-by: Daniel Kurtz <djkurtz@google.com>
Diffstat (limited to 'src')
-rw-r--r--src/drivers/i2c/tpm/cr50.c50
1 files changed, 39 insertions, 11 deletions
diff --git a/src/drivers/i2c/tpm/cr50.c b/src/drivers/i2c/tpm/cr50.c
index b0d3b29044..19c8f6bcbb 100644
--- a/src/drivers/i2c/tpm/cr50.c
+++ b/src/drivers/i2c/tpm/cr50.c
@@ -456,10 +456,44 @@ int tpm_vendor_probe(unsigned int bus, uint32_t addr)
return 0;
}
+static int cr50_i2c_probe(struct tpm_chip *chip, uint32_t *did_vid)
+{
+ int retries;
+
+ /*
+ * 150 ms should be enough to synchronize with the TPM even under the
+ * worst nested reset request conditions. In vast majority of cases
+ * there would be no wait at all.
+ */
+ printk(BIOS_INFO, "Probing TPM I2C: ");
+
+ for (retries = 15; retries > 0; retries--) {
+ int rc;
+
+ rc = cr50_i2c_read(chip, TPM_DID_VID(0), (uint8_t *)did_vid, 4);
+
+ /* Exit once DID and VID verified */
+ if (!rc && (*did_vid == CR50_DID_VID)) {
+ printk(BIOS_INFO, "done! DID_VID 0x%08x\n", *did_vid);
+ return 0;
+ }
+
+ /* TPM might be resetting, let's retry in a bit. */
+ mdelay(10);
+ printk(BIOS_INFO, ".");
+ }
+
+ /*
+ * I2C reads failed, or the DID and VID didn't match
+ */
+ printk(BIOS_ERR, "DID_VID 0x%08x not recognized\n", *did_vid);
+ return -1;
+}
+
int tpm_vendor_init(struct tpm_chip *chip, unsigned int bus, uint32_t dev_addr)
{
struct tpm_inf_dev *tpm_dev = car_get_var_ptr(&g_tpm_dev);
- uint32_t vendor;
+ uint32_t did_vid = 0;
if (dev_addr == 0) {
printk(BIOS_ERR, "%s: missing device address\n", __func__);
@@ -471,6 +505,9 @@ int tpm_vendor_init(struct tpm_chip *chip, unsigned int bus, uint32_t dev_addr)
cr50_vendor_init(chip);
+ if (cr50_i2c_probe(chip, &did_vid))
+ return -1;
+
if (ENV_VERSTAGE || ENV_BOOTBLOCK)
if (process_reset(chip))
return -1;
@@ -478,17 +515,8 @@ int tpm_vendor_init(struct tpm_chip *chip, unsigned int bus, uint32_t dev_addr)
if (claim_locality(chip))
return -1;
- /* Read four bytes from DID_VID register */
- if (cr50_i2c_read(chip, TPM_DID_VID(0), (uint8_t *)&vendor, 4) < 0)
- return -1;
-
- if (vendor != CR50_DID_VID) {
- printk(BIOS_DEBUG, "Vendor ID 0x%08x not recognized\n", vendor);
- return -1;
- }
-
printk(BIOS_DEBUG, "cr50 TPM 2.0 (i2c %u:0x%02x id 0x%x)\n",
- bus, dev_addr, vendor >> 16);
+ bus, dev_addr, did_vid >> 16);
chip->is_open = 1;
return 0;