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spi/tpm: read TPM version in larger chunks 

The TPM version string has become much longer recently, and the
TPM_FW_VER register available on VID 1ae0 devices supports reading in
arbitrary size quantities.

Let's read 50 bytes at a time to reduce the SPI register read wrapper
overhead, and increase the length limit to 300 bytes to accommodate
longer version strings.

TEST=verified on the Kevin device:
 localhost ~ # grep cr50 /sys/firmware/log
 Firmware version: RO_A: 0.0.1/84e2dde7 RO_B:* 0.0.2/13eda43f RW_A:* cr50_v1.1.5005-444ddb7 RW_B: cr50_v1.1.5005-5aac83c
 cr50_v1.1.5005-444ddb7 private-cr51:v0.0.66-bd9a0fe tpm2:v0.0.259-8f3d735 cryptoc:v0.0.4-5319e83 2016-07-31 10:58:05 vbendeb@kvasha

Change-Id: Ifaf28c1a9a3990372a9cec108c098edbe50d3243
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://review.coreboot.org/16000
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
This commit is contained in:
Vadim Bendebury 2016-07-31 11:19:20 -07:00
parent d1a00515ff
commit 9e561f8e80
1 changed files with 15 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
src/drivers/spi/tpm/tpm.c
View File

@ -359,8 +359,14 @@ int tpm2_init(struct spi_slave *spi_if)
/* Let's report device FW version if available. */ /* Let's report device FW version if available. */
if (tpm_info.vendor_id == 0x1ae0) { if (tpm_info.vendor_id == 0x1ae0) {
int chunk_count = 0; int chunk_count = 0;
uint32_t chunk = 0; size_t chunk_size;
char vstr[sizeof(chunk) + 1]; /* room for 4 chars + zero */ /*
* let's read 50 bytes at a time; leave room for the trailing
* zero.
*/
char vstr[51];
chunk_size = sizeof(vstr) - 1;
printk(BIOS_INFO, "Firmware version: "); printk(BIOS_INFO, "Firmware version: ");
@ -368,21 +374,20 @@ int tpm2_init(struct spi_slave *spi_if)
* Does not really matter what's written, this just makes sure * Does not really matter what's written, this just makes sure
* the version is reported from the beginning. * the version is reported from the beginning.
*/ */
tpm2_write_reg(TPM_FW_VER, &chunk, sizeof(chunk)); tpm2_write_reg(TPM_FW_VER, &chunk_size, 1);
/* Print it out in 4 byte chunks. */ /* Print it out in sizeof(vstr) - 1 byte chunks. */
vstr[sizeof(vstr) - 1] = 0; vstr[chunk_size] = 0;
do { do {
tpm2_read_reg(TPM_FW_VER, vstr, sizeof(chunk)); tpm2_read_reg(TPM_FW_VER, vstr, chunk_size);
printk(BIOS_INFO, "%s", vstr); printk(BIOS_INFO, "%s", vstr);
/* /*
* While string is not over, and no more than 200 * While string is not over, and is no longer than 300
* characters. * characters.
* This is likely result in one extra printk()
* invocation with an empty string, not a big deal.
*/ */
} while (vstr[0] && (chunk_count++ < (200 / sizeof(chunk)))); } while (vstr[chunk_size - 1] &&
(chunk_count++ < (300 / chunk_size)));
printk(BIOS_INFO, "\n"); printk(BIOS_INFO, "\n");
} }