Re: [PATCH v6 11/11] bus: mhi: core: Introduce sysfs entries for MHI

bbhatt@xxxxxxxxxxxxxx · Mon, 10 Aug 2020 12:11:04 -0700

On 2020-08-06 22:22, Manivannan Sadhasivam wrote:
On Mon, Jul 27, 2020 at 07:02:20PM -0700, Bhaumik Bhatt wrote:
Introduce sysfs entries to enable userspace clients the ability to 
read
the serial number and the OEM PK Hash values obtained from BHI. OEMs
need to read these device-specific hardware information values through
userspace for factory testing purposes and cannot be exposed via 
degbufs
as it may remain disabled for performance reasons. Also, update the
documentation for ABI to include these entries.

Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
---
 Documentation/ABI/stable/sysfs-bus-mhi | 21 ++++++++++++++
 MAINTAINERS                            |  1 +
 drivers/bus/mhi/core/init.c            | 53 
++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+)
 create mode 100644 Documentation/ABI/stable/sysfs-bus-mhi

diff --git a/Documentation/ABI/stable/sysfs-bus-mhi 
b/Documentation/ABI/stable/sysfs-bus-mhi
new file mode 100644
index 0000000..1d5d0d6
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-bus-mhi
@@ -0,0 +1,21 @@
+What:		/sys/bus/mhi/devices/.../serialnumber
+Date:		Jul 2020
+KernelVersion:	5.8
+Contact:	Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
+Description:	The file holds the serial number of the client device 
obtained
+		using a BHI (Boot Host Interface) register read after at least
+		one attempt to power up the device has been done. If read
+		without having the device power on at least once, the file will
+		read all 0's.
+Users:		Any userspace application or clients interested in device 
info.

I think you're not using tabs here and that's why it is showing 
mangled. Please
use tabs as like other files.

Thanks,
Mani

Hi Mani,

I am using tabs actually. I, in fact, copied another file 
(sysfs-bus-vmbus) and only modified the
required entries and did a diff to confirm.

I doubt there is more I can do.

Please let me know if the next patch is acceptable soon.

+
+What:		/sys/bus/mhi/devices/.../oem_pk_hash
+Date:		Jul 2020
+KernelVersion:	5.8
+Contact:	Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
+Description:	The file holds the OEM PK Hash value of the endpoint 
device
+		obtained using a BHI (Boot Host Interface) register read after
+		at least one attempt to power up the device has been done. If
+		read without having the device power on at least once, the file
+		will read all 0's.
+Users:		Any userspace application or clients interested in device 
info.
diff --git a/MAINTAINERS b/MAINTAINERS
index e64e5db..5e49316 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11018,6 +11018,7 @@ M:	Hemant Kumar <hemantk@xxxxxxxxxxxxxx>
 L:	linux-arm-msm@xxxxxxxxxxxxxxx
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mani/mhi.git
+F:	Documentation/ABI/stable/sysfs-bus-mhi
 F:	Documentation/mhi/
 F:	drivers/bus/mhi/
 F:	include/linux/mhi.h
diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index 972dbf0..c086ef2 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -76,6 +76,56 @@ const char *to_mhi_pm_state_str(enum mhi_pm_state 
state)
 	return mhi_pm_state_str[index];
 }

+static ssize_t serial_number_show(struct device *dev,
+				  struct device_attribute *attr,
+				  char *buf)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+
+	return snprintf(buf, PAGE_SIZE, "Serial Number: %u\n",
+			mhi_cntrl->serial_number);
+}
+static DEVICE_ATTR_RO(serial_number);
+
+static ssize_t oem_pk_hash_show(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	int i, cnt = 0;
+
+	for (i = 0; i < ARRAY_SIZE(mhi_cntrl->oem_pk_hash); i++)
+		cnt += snprintf(buf + cnt, PAGE_SIZE - cnt,
+				"OEMPKHASH[%d]: 0x%x\n", i,
+				mhi_cntrl->oem_pk_hash[i]);
+
+	return cnt;
+}
+static DEVICE_ATTR_RO(oem_pk_hash);
+
+static struct attribute *mhi_sysfs_attrs[] = {
+	&dev_attr_serial_number.attr,
+	&dev_attr_oem_pk_hash.attr,
+	NULL,
+};
+
+static const struct attribute_group mhi_sysfs_group = {
+	.attrs = mhi_sysfs_attrs,
+};
+
+static int mhi_create_sysfs(struct mhi_controller *mhi_cntrl)
+{
+	return sysfs_create_group(&mhi_cntrl->mhi_dev->dev.kobj,
+				  &mhi_sysfs_group);
+}
+
+static void mhi_destroy_sysfs(struct mhi_controller *mhi_cntrl)
+{
+	sysfs_remove_group(&mhi_cntrl->mhi_dev->dev.kobj, &mhi_sysfs_group);
+}
+
 /* MHI protocol requires the transfer ring to be aligned with ring 
length */
 static int mhi_alloc_aligned_ring(struct mhi_controller *mhi_cntrl,
 				  struct mhi_ring *ring,
@@ -917,6 +967,8 @@ int mhi_register_controller(struct mhi_controller 
*mhi_cntrl,
 	mhi_cntrl->mhi_dev = mhi_dev;

 	mhi_create_debugfs(mhi_cntrl);
+	if (mhi_create_sysfs(mhi_cntrl))
+		dev_err(mhi_cntrl->cntrl_dev, "Failed to create sysfs entries\n");

 	return 0;

@@ -940,6 +992,7 @@ void mhi_unregister_controller(struct 
mhi_controller *mhi_cntrl)
 	struct mhi_chan *mhi_chan = mhi_cntrl->mhi_chan;
 	unsigned int i;

+	mhi_destroy_sysfs(mhi_cntrl);
 	mhi_destroy_debugfs(mhi_cntrl);

 	kfree(mhi_cntrl->mhi_cmd);
--
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