[PATCH v3 2/2] tpm: Add reserved memory event log

Eddie James
2023-01-26T21:08:33Z

Some platforms may desire to pass the event log up to Linux in the
form of a reserved memory region. In particular, this is desirable
for embedded systems or baseboard management controllers (BMCs)
booting with U-Boot. IBM OpenBMC BMCs will be the first user.
Add support for the reserved memory in the TPM core to find the
region and map it.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
drivers/char/tpm/eventlog/of.c | 38 +++++++++++++++++++++++++++++++++-
1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
index 741ab2204b11..c815cadf00a4 100644
--- a/drivers/char/tpm/eventlog/of.c
+++ b/drivers/char/tpm/eventlog/of.c
@@ -12,12 +12,48 @@

#include <linux/device.h>
#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
#include <linux/tpm_eventlog.h>

#include "../tpm.h"
#include "common.h"

+static int tpm_read_log_memory_region(struct tpm_chip *chip)
+{
+ struct device_node *node;
+ struct resource res;
+ int rc;
+
+ node = of_parse_phandle(chip->dev.parent->of_node, "memory-region", 0);
+ if (!node) {
+ dev_info(&chip->dev, "no phandle\n");
+ return -ENODEV;
+ }
+
+ rc = of_address_to_resource(node, 0, &res);
+ of_node_put(node);
+ if (rc) {
+ dev_info(&chip->dev, "no mem\n");
+ return rc;
+ }
+
+ chip->log.bios_event_log = devm_memremap(&chip->dev, res.start, resource_size(&res),
+ MEMREMAP_WB);
+ if (!chip->log.bios_event_log) {
+ dev_info(&chip->dev, "err memremap\n");
+ return -ENOMEM;
+ }
+
+ chip->log.bios_event_log_end = chip->log.bios_event_log + resource_size(&res);
+
+ return chip->flags & TPM_CHIP_FLAG_TPM2 ? EFI_TCG2_EVENT_LOG_FORMAT_TCG_2 :
+ EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
+}
+
int tpm_read_log_of(struct tpm_chip *chip)
{
struct device_node *np;
@@ -39,7 +75,7 @@ int tpm_read_log_of(struct tpm_chip *chip)
sizep = of_get_property(np, "linux,sml-size", NULL);
basep = of_get_property(np, "linux,sml-base", NULL);
if (sizep == NULL && basep == NULL)
- return -ENODEV;
+ return tpm_read_log_memory_region(chip);
if (sizep == NULL || basep == NULL)
return -EIO;

--
2.31.1