scsi: ufs: Add HCI capabilities sysfs group

The standard register map of UFSHCI is comprised of several groups. The
first group (starting from offset 0x00), is the host capabilities group.
It contains some interesting information that otherwise is not available,
e.g. the UFS version of the platform etc.

Reviewed-by: Keoseong Park <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
Reviewed-by: Bean Huo <[e-mail]>
Signed-off-by: Avri Altman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin K. Petersen <[e-mail]>

Documentation/ABI/testing/sysfs-driver-ufs

···
 Description:
 		rtc_update_ms indicates how often the host should synchronize or update the
 		UFS RTC. If set to 0, this will disable UFS RTC periodic update.
+
+What:		/sys/devices/platform/.../ufshci_capabilities/version
+Date:		August 2024
+Contact:	Avri Altman <[e-mail]>
+Description:
+		Host Capabilities register group: UFS version register.
+		Symbol - VER.  This file shows the UFSHCD version.
+		Example: Version 3.12 would be represented as 0000_0312h.
+		The file is read only.
+
+What:		/sys/devices/platform/.../ufshci_capabilities/product_id
+Date:		August 2024
+Contact:	Avri Altman <[e-mail]>
+Description:
+		Host Capabilities register group: product ID register.
+		Symbol - HCPID.  This file shows the UFSHCD product id.
+		The content of this register is vendor specific.
+		The file is read only.
+
+What:		/sys/devices/platform/.../ufshci_capabilities/man_id
+Date:		August 2024
+Contact:	Avri Altman <[e-mail]>
+Description:
+		Host Capabilities register group: manufacturer ID register.
+		Symbol - HCMID. This file shows the UFSHCD manufacturer id.
+		The Manufacturer ID is defined by JEDEC in JEDEC-JEP106.
+		The file is read only.

drivers/ufs/core/ufs-sysfs.c

···
 	.attrs = ufs_sysfs_capabilities_attrs,
 };
 
+static ssize_t version_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "0x%x\n", hba->ufs_version);
+}
+
+static ssize_t product_id_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	int ret;
+	u32 val;
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+
+	ret = ufshcd_read_hci_reg(hba, &val, REG_CONTROLLER_PID);
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "0x%x\n", val);
+}
+
+static ssize_t man_id_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	int ret;
+	u32 val;
+	struct ufs_hba *hba = dev_get_drvdata(dev);
+
+	ret = ufshcd_read_hci_reg(hba, &val, REG_CONTROLLER_MID);
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "0x%x\n", val);
+}
+
+static DEVICE_ATTR_RO(version);
+static DEVICE_ATTR_RO(product_id);
+static DEVICE_ATTR_RO(man_id);
+
+static struct attribute *ufs_sysfs_ufshci_cap_attrs[] = {
+	&dev_attr_version.attr,
+	&dev_attr_product_id.attr,
+	&dev_attr_man_id.attr,
+	NULL
+};
+
+static const struct attribute_group ufs_sysfs_ufshci_group = {
+	.name = "ufshci_capabilities",
+	.attrs = ufs_sysfs_ufshci_cap_attrs,
+};
+
 static ssize_t monitor_enable_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
 {
···
 static const struct attribute_group *ufs_sysfs_groups[] = {
 	&ufs_sysfs_default_group,
 	&ufs_sysfs_capabilities_group,
+	&ufs_sysfs_ufshci_group,
 	&ufs_sysfs_monitor_group,
 	&ufs_sysfs_power_info_group,
 	&ufs_sysfs_device_descriptor_group,