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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>
This commit is contained in:
Keith Short 2018-12-17 14:21:46 -07:00 committed by Patrick Georgi
parent fc707892de
commit 514363541f
1 changed files with 39 additions and 11 deletions
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50
src/drivers/i2c/tpm/cr50.c
View File

@ -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;