platform/x86/intel/sdsi: Add meter certificate support

Add support for reading the meter certificate from Intel On Demand
hardware.  The meter certificate [1] is used to access the utilization
metrics of enabled features in support of the Intel On Demand consumption
model. Similar to the state certificate, the meter certificate is read by
mailbox command.

While making similar changes also use the BIN_ATTR_ADMIN_RO helper to
create the 'registers' sysfs file.

Link: https://github.com/intel-sandbox/debox1.intel_sdsi/blob/gnr-review/meter-certificate.rst [1]
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Link: https://lore.kernel.org/r/20221119002343.1281885-5-david.e.box@linux.intel.comReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Documentation/ABI/testing/sysfs-driver-intel_sdsi

@@ -69,6 +69,16 @@ Description:
 		the CPU configuration is updated. A cold reboot is required to
 		fully activate the feature. Mailbox command.
 
+What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/meter_certificate
+Date:		Nov 2022
+KernelVersion:	6.2
+Contact:	"David E. Box" <david.e.box@linux.intel.com>
+Description:
+		(RO) Used to read back the current meter certificate for the CPU
+		from Intel On Demand hardware. The meter certificate contains
+		utilization metrics of On Demand enabled features. Mailbox
+		command.
+
 What:		/sys/bus/auxiliary/devices/intel_vsec.sdsi.X/state_certificate
 Date:		Feb 2022
 KernelVersion:	5.18

drivers/platform/x86/intel/sdsi.c

@@ -41,6 +41,7 @@
 
 #define SDSI_ENABLED_FEATURES_OFFSET	16
 #define SDSI_FEATURE_SDSI		BIT(3)
+#define SDSI_FEATURE_METERING		BIT(26)
 
 #define SDSI_SOCKET_ID_OFFSET		64
 #define SDSI_SOCKET_ID			GENMASK(3, 0)
@@ -83,9 +84,10 @@
 #define GUID_V2_REGS_SIZE		80
 
 enum sdsi_command {
-	SDSI_CMD_PROVISION_AKC		= 0x04,
-	SDSI_CMD_PROVISION_CAP		= 0x08,
-	SDSI_CMD_READ_STATE		= 0x10,
+	SDSI_CMD_PROVISION_AKC		= 0x0004,
+	SDSI_CMD_PROVISION_CAP		= 0x0008,
+	SDSI_CMD_READ_STATE		= 0x0010,
+	SDSI_CMD_READ_METER		= 0x0014,
 };
 
 struct sdsi_mbox_info {
@@ -401,13 +403,10 @@ static ssize_t provision_cap_write(struct file *filp, struct kobject *kobj,
 }
 static BIN_ATTR_WO(provision_cap, SDSI_SIZE_WRITE_MSG);
 
-static long state_certificate_read(struct file *filp, struct kobject *kobj,
-				   struct bin_attribute *attr, char *buf, loff_t off,
-				   size_t count)
+static ssize_t
+certificate_read(u64 command, struct sdsi_priv *priv, char *buf, loff_t off,
+		 size_t count)
 {
-	struct device *dev = kobj_to_dev(kobj);
-	struct sdsi_priv *priv = dev_get_drvdata(dev);
-	u64 command = SDSI_CMD_READ_STATE;
 	struct sdsi_mbox_info info;
 	size_t size;
 	int ret;
@@ -444,7 +443,30 @@ static long state_certificate_read(struct file *filp, struct kobject *kobj,
 
 	return size;
 }
-static BIN_ATTR(state_certificate, 0400, state_certificate_read, NULL, SDSI_SIZE_READ_MSG);
+
+static ssize_t
+state_certificate_read(struct file *filp, struct kobject *kobj,
+		       struct bin_attribute *attr, char *buf, loff_t off,
+		       size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct sdsi_priv *priv = dev_get_drvdata(dev);
+
+	return certificate_read(SDSI_CMD_READ_STATE, priv, buf, off, count);
+}
+static BIN_ATTR_ADMIN_RO(state_certificate, SDSI_SIZE_READ_MSG);
+
+static ssize_t
+meter_certificate_read(struct file *filp, struct kobject *kobj,
+		       struct bin_attribute *attr, char *buf, loff_t off,
+		       size_t count)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct sdsi_priv *priv = dev_get_drvdata(dev);
+
+	return certificate_read(SDSI_CMD_READ_METER, priv, buf, off, count);
+}
+static BIN_ATTR_ADMIN_RO(meter_certificate, SDSI_SIZE_READ_MSG);
 
 static ssize_t registers_read(struct file *filp, struct kobject *kobj,
 			      struct bin_attribute *attr, char *buf, loff_t off,
@@ -470,11 +492,12 @@ static ssize_t registers_read(struct file *filp, struct kobject *kobj,
 
 	return count;
 }
-static BIN_ATTR(registers, 0400, registers_read, NULL, SDSI_SIZE_REGS);
+static BIN_ATTR_ADMIN_RO(registers, SDSI_SIZE_REGS);
 
 static struct bin_attribute *sdsi_bin_attrs[] = {
 	&bin_attr_registers,
 	&bin_attr_state_certificate,
+	&bin_attr_meter_certificate,
 	&bin_attr_provision_akc,
 	&bin_attr_provision_cap,
 	NULL
@@ -494,6 +517,10 @@ sdsi_battr_is_visible(struct kobject *kobj, struct bin_attribute *attr, int n)
 	if (!(priv->features & SDSI_FEATURE_SDSI))
 		return 0;
 
+	if (attr == &bin_attr_meter_certificate)
+		return (priv->features & SDSI_FEATURE_METERING) ?
+				attr->attr.mode : 0;
+
 	return attr->attr.mode;
 }