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bus: mhi: host: Read PK HASH dynamically

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The OEM PK HASH registers in the BHI region are read once during firmware
load (boot), cached, and displayed on demand via sysfs. This has a few
problems - if firmware load is skipped, the registers will not be read and
if the register values change over the life of the device the local cache
will be out of sync.

Qualcomm Cloud AI 100 can expose both these problems. It is possible for
mhi_async_power_up() to be invoked while the device is in AMSS EE, which
would bypass firmware loading. Also, Qualcomm Cloud AI 100 has 5 PK HASH
slots which can be dynamically provisioned while the device is active,
which would result in the values changing and users may want to know what
keys are active.

Address these concerns by reading the PK HASH registers on-demand during
the sysfs read. This will result in showing the most current information.

Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20240105174253.863388-1-quic_jhugo@quicinc.com
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
This commit is contained in:
Jeffrey Hugo 2024-01-05 10:42:53 -07:00 committed by Manivannan Sadhasivam
parent bce3f77068
commit 8ddf54a321
3 changed files with 13 additions and 16 deletions
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11
drivers/bus/mhi/host/boot.c
View file

@ -395,7 +395,7 @@ void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl)
void *buf;
dma_addr_t dma_addr;
size_t size, fw_sz;
int i, ret;
int ret;
if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
dev_err(dev, "Device MHI is not in valid state\n");
@ -408,15 +408,6 @@ void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl)
if (ret)
dev_err(dev, "Could not capture serial number via BHI\n");
for (i = 0; i < ARRAY_SIZE(mhi_cntrl->oem_pk_hash); i++) {
ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_OEMPKHASH(i),
&mhi_cntrl->oem_pk_hash[i]);
if (ret) {
dev_err(dev, "Could not capture OEM PK HASH via BHI\n");
break;
}
}
/* wait for ready on pass through or any other execution environment */
if (!MHI_FW_LOAD_CAPABLE(mhi_cntrl->ee))
goto fw_load_ready_state;

16
drivers/bus/mhi/host/init.c
View file

@ -98,11 +98,19 @@ static ssize_t oem_pk_hash_show(struct device *dev,
{
struct mhi_device *mhi_dev = to_mhi_device(dev);
struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
int i, cnt = 0;
u32 hash_segment[MHI_MAX_OEM_PK_HASH_SEGMENTS];
int i, cnt = 0, ret;
for (i = 0; i < ARRAY_SIZE(mhi_cntrl->oem_pk_hash); i++)
cnt += sysfs_emit_at(buf, cnt, "OEMPKHASH[%d]: 0x%x\n",
i, mhi_cntrl->oem_pk_hash[i]);
for (i = 0; i < MHI_MAX_OEM_PK_HASH_SEGMENTS; i++) {
ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_OEMPKHASH(i), &hash_segment[i]);
if (ret) {
dev_err(dev, "Could not capture OEM PK HASH\n");
return ret;
}
}
for (i = 0; i < MHI_MAX_OEM_PK_HASH_SEGMENTS; i++)
cnt += sysfs_emit_at(buf, cnt, "OEMPKHASH[%d]: 0x%x\n", i, hash_segment[i]);
return cnt;
}

2
include/linux/mhi.h
View file

@ -325,7 +325,6 @@ struct mhi_controller_config {
* @major_version: MHI controller major revision number
* @minor_version: MHI controller minor revision number
* @serial_number: MHI controller serial number obtained from BHI
* @oem_pk_hash: MHI controller OEM PK Hash obtained from BHI
* @mhi_event: MHI event ring configurations table
* @mhi_cmd: MHI command ring configurations table
* @mhi_ctxt: MHI device context, shared memory between host and device
@ -413,7 +412,6 @@ struct mhi_controller {
u32 major_version;
u32 minor_version;
u32 serial_number;
u32 oem_pk_hash[MHI_MAX_OEM_PK_HASH_SEGMENTS];
struct mhi_event *mhi_event;
struct mhi_cmd *mhi_cmd;