mfd: intel-m10-bmc: Expose MAC address and count

Create two sysfs entries for exposing the MAC address and count
from the MAX10 BMC register space. The MAC address is the first
in a sequential block of MAC addresses reserved for the FPGA card.
The MAC count is the number of MAC addresses in the reserved block.

Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

Author: Russ Weight

Documentation/ABI/testing/sysfs-driver-intel-m10-bmc

@@ -13,3 +13,24 @@ Contact:	Xu Yilun <yilun.xu@intel.com>
 Description:	Read only. Returns the firmware version of Intel MAX10
 		BMC chip.
 		Format: "0x%x".
+
+What:		/sys/bus/spi/devices/.../mac_address
+Date:		January 2021
+KernelVersion:  5.12
+Contact:	Russ Weight <russell.h.weight@intel.com>
+Description:	Read only. Returns the first MAC address in a block
+		of sequential MAC addresses assigned to the board
+		that is managed by the Intel MAX10 BMC. It is stored in
+		FLASH storage and is mirrored in the MAX10 BMC register
+		space.
+		Format: "%02x:%02x:%02x:%02x:%02x:%02x".
+
+What:		/sys/bus/spi/devices/.../mac_count
+Date:		January 2021
+KernelVersion:  5.12
+Contact:	Russ Weight <russell.h.weight@intel.com>
+Description:	Read only. Returns the number of sequential MAC
+		addresses assigned to the board managed by the Intel
+		MAX10 BMC. This value is stored in FLASH and is mirrored
+		in the MAX10 BMC register space.
+		Format: "%u".

drivers/mfd/intel-m10-bmc.c

@@ -60,9 +60,52 @@ static ssize_t bmcfw_version_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(bmcfw_version);
 
+static ssize_t mac_address_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct intel_m10bmc *max10 = dev_get_drvdata(dev);
+	unsigned int macaddr_low, macaddr_high;
+	int ret;
+
+	ret = m10bmc_sys_read(max10, M10BMC_MAC_LOW, &macaddr_low);
+	if (ret)
+		return ret;
+
+	ret = m10bmc_sys_read(max10, M10BMC_MAC_HIGH, &macaddr_high);
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "%02x:%02x:%02x:%02x:%02x:%02x\n",
+			  (u8)FIELD_GET(M10BMC_MAC_BYTE1, macaddr_low),
+			  (u8)FIELD_GET(M10BMC_MAC_BYTE2, macaddr_low),
+			  (u8)FIELD_GET(M10BMC_MAC_BYTE3, macaddr_low),
+			  (u8)FIELD_GET(M10BMC_MAC_BYTE4, macaddr_low),
+			  (u8)FIELD_GET(M10BMC_MAC_BYTE5, macaddr_high),
+			  (u8)FIELD_GET(M10BMC_MAC_BYTE6, macaddr_high));
+}
+static DEVICE_ATTR_RO(mac_address);
+
+static ssize_t mac_count_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct intel_m10bmc *max10 = dev_get_drvdata(dev);
+	unsigned int macaddr_high;
+	int ret;
+
+	ret = m10bmc_sys_read(max10, M10BMC_MAC_HIGH, &macaddr_high);
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "%u\n",
+			  (u8)FIELD_GET(M10BMC_MAC_COUNT, macaddr_high));
+}
+static DEVICE_ATTR_RO(mac_count);
+
 static struct attribute *m10bmc_attrs[] = {
 	&dev_attr_bmc_version.attr,
 	&dev_attr_bmcfw_version.attr,
+	&dev_attr_mac_address.attr,
+	&dev_attr_mac_count.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(m10bmc);

include/linux/mfd/intel-m10-bmc.h

@@ -15,6 +15,15 @@
 
 /* Register offset of system registers */
 #define NIOS2_FW_VERSION		0x0
+#define M10BMC_MAC_LOW			0x10
+#define M10BMC_MAC_BYTE4		GENMASK(7, 0)
+#define M10BMC_MAC_BYTE3		GENMASK(15, 8)
+#define M10BMC_MAC_BYTE2		GENMASK(23, 16)
+#define M10BMC_MAC_BYTE1		GENMASK(31, 24)
+#define M10BMC_MAC_HIGH			0x14
+#define M10BMC_MAC_BYTE6		GENMASK(7, 0)
+#define M10BMC_MAC_BYTE5		GENMASK(15, 8)
+#define M10BMC_MAC_COUNT		GENMASK(23, 16)
 #define M10BMC_TEST_REG			0x3c
 #define M10BMC_BUILD_VER		0x68
 #define M10BMC_VER_MAJOR_MSK		GENMASK(23, 16)