[coreboot-gerrit] Change in coreboot[master]: drivers/spi/tpm: Re-organize the TPM Initialization

[Karthik Ramasubramanian (Code Review)]

Karthik Ramasubramanian has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/44276 )

Change subject: drivers/spi/tpm: Re-organize the TPM Initialization
......................................................................

drivers/spi/tpm: Re-organize the TPM Initialization

Re-organize the tpm_init2 to facilitate caching the TPM firmware. Also
read the TPM firmware version only during ramstage where it will be
used. In other stages, it is read, logged and dropped.

BUG=None
TEST=Ensure that the device boots to OS. Ensure that the TPM
initialization sequence works as expected.

Change-Id: I94fef8ed813f4c0482b23ba513465faaf1ceae9f
Signed-off-by: Karthikeyan Ramasubramanian 
---
M src/drivers/spi/tpm/tpm.c
1 file changed, 58 insertions(+), 46 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/76/44276/1

diff --git a/src/drivers/spi/tpm/tpm.c b/src/drivers/spi/tpm/tpm.c
index 4263dce..b44c87e 100644
--- a/src/drivers/spi/tpm/tpm.c
+++ b/src/drivers/spi/tpm/tpm.c
@@ -34,6 +34,8 @@

#define CR50_TIMEOUT_INIT_MS 30000 /* Very long timeout for TPM init */

+#define TPM_FW_VER_STRLEN	301
+
 /* SPI slave structure for TPM device. */
 static struct spi_slave spi_slave;

@@ -421,23 +423,46 @@
    return 0;
 }

+static void read_tpm_fw_version(void)
+{
+	char vstr[TPM_FW_VER_STRLEN];
+	int chunk_count = 0;
+	/*
+	 * let's read 50 bytes at a time; leave room for the trailing
+	 * zero.
+	 */
+	size_t chunk_size = 50;
+
+	/* Only cr50 reports device FW version */
+	if (tpm_info.vendor_id != 0x1ae0)
+		return;
+
+	/*
+	 * Does not really matter what's written, this just makes sure
+	 * the version is reported from the beginning.
+	 */
+	tpm2_write_reg(TPM_FW_VER, vstr, 1);
+
+	do {
+		tpm2_read_reg(TPM_FW_VER,
+			      vstr + chunk_count * chunk_size, chunk_size);
+		chunk_count++;
+	} while (vstr[chunk_count * chunk_size - 1] &&
+		 (chunk_count + 1) * chunk_size < sizeof(vstr));
+	vstr[chunk_count * chunk_size] = 0;
+	printk(BIOS_INFO, "Firmware version: %s\n", vstr);
+}
+
 /* Device/vendor ID values of the TPM devices this driver supports. */
 static const uint32_t supported_did_vids[] = {
    0x00281ae0,  /* H1 based Cr50 security chip. */
    0x0000104a   /* ST33HTPH2E32 */
 };

-int tpm2_init(struct spi_slave *spi_if)
+static int probe_tpm(uint32_t *did_vid)
 {
-	uint32_t did_vid, status;
-	uint8_t cmd;
    int retries;

-	memcpy(&spi_slave, spi_if, sizeof(*spi_if));
-
-	/* clear any pending IRQs */
-	tis_plat_irq_status();
-
    /*
     * 150 ms should be enough to synchronize with the TPM even under the
     * worst nested reset request conditions. In vast majority of cases
@@ -447,11 +472,11 @@
    for (retries = 15; retries > 0; retries--) {
    	int i;

-		/* In case of failure to read div_vid is set to zero. */
-		tpm2_read_reg(TPM_DID_VID_REG, &did_vid, sizeof(did_vid));
+		/* In case of failure to read did_vid is set to zero. */
+		tpm2_read_reg(TPM_DID_VID_REG, did_vid, sizeof(*did_vid));

for (i = 0; i < ARRAY_SIZE(supported_did_vids); i++)
-			if (did_vid == supported_did_vids[i])
+			if (*did_vid == supported_did_vids[i])
    			break; /* TPM is up and ready. */

if (i < ARRAY_SIZE(supported_did_vids))
@@ -469,6 +494,22 @@
    }

printk(BIOS_INFO, " done!\n");
+	return 0;
+}
+
+int tpm2_init(struct spi_slave *spi_if)
+{
+	uint32_t did_vid, status;
+	uint8_t cmd;
+
+	memcpy(&spi_slave, spi_if, sizeof(*spi_if));
+
+	/* clear any pending IRQs */
+	tis_plat_irq_status();
+
+	/* Probe TPM and get the did_vid */
+	if (probe_tpm(&did_vid))
+		return -1;

// FIXME: Move this to tpm_setup()
    if (ENV_SEPARATE_VERSTAGE || ENV_BOOTBLOCK || !CONFIG(VBOOT))
@@ -501,41 +542,12 @@
    printk(BIOS_INFO, "Connected to device vid:did:rid of %4.4x:%4.4x:%2.2x\n",
           tpm_info.vendor_id, tpm_info.device_id, tpm_info.revision);

-	/* Let's report device FW version if available. */
-	if (tpm_info.vendor_id == 0x1ae0) {
-		int chunk_count = 0;
-		size_t chunk_size;
-		/*
-		 * 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: ");
-
-		/*
-		 * Does not really matter what's written, this just makes sure
-		 * the version is reported from the beginning.
-		 */
-		tpm2_write_reg(TPM_FW_VER, &chunk_size, 1);
-
-		/* Print it out in sizeof(vstr) - 1 byte chunks. */
-		vstr[chunk_size] = 0;
-		do {
-			tpm2_read_reg(TPM_FW_VER, vstr, chunk_size);
-			printk(BIOS_INFO, "%s", vstr);
-
-			/*
-			 * While string is not over, and is no longer than 300
-			 * characters.
-			 */
-		} while (vstr[chunk_size - 1] &&
-			 (chunk_count++ < (300 / chunk_size)));
-
-		printk(BIOS_INFO, "\n");
-	}
+	/*
+	 * Firmware version is used only in ramstage. In other stages it is
+	 * read, logged and dropped. So read FW version only in ramstage.
+	 */
+	if (ENV_RAMSTAGE)
+		read_tpm_fw_version();
    return 0;
 }