[PATCH v3 2/3] ACPI: move ACPI functionality out of r8152 driver

[Charles Hyde <chip.programmer@gmail.com>]

This change moves ACPI functionality out of the Realtek r8152 driver to
its own source and header file, making it available to other drivers as
needed now and into the future.  At the time this ACPI snippet was
introduced in 2016, only the Realtek driver made use of it in support of
Dell's enterprise IT policy efforts.  There comes now a need for this
same support in a different driver, also in support of Dell's enterprise
IT policy efforts.

Signed-off-by: Charles Hyde <charles.hyde@dellteam.com>
Cc: Mario Limonciello <mario.limonciello@dell.com>
Cc: chip.programmer@gmail.com
Cc: Realtek linux nic maintainers <nic_swsd@realtek.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
---
 drivers/acpi/Makefile            |  1 +
 drivers/acpi/acpi_mac_passthru.c | 63 ++++++++++++++++++++++++++++++++
 drivers/net/usb/r8152.c          | 44 ++--------------------
 include/acpi/acpi_mac_passthru.h | 27 ++++++++++++++
 4 files changed, 95 insertions(+), 40 deletions(-)
 create mode 100644 drivers/acpi/acpi_mac_passthru.c
 create mode 100644 include/acpi/acpi_mac_passthru.h

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 5d361e4e3405..6bc2748f0e00 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -66,6 +66,7 @@ acpi-$(CONFIG_ACPI_WATCHDOG)	+= acpi_watchdog.o
 acpi-$(CONFIG_ACPI_ADXL)	+= acpi_adxl.o
 
 # These are (potentially) separate modules
+acpi-y				+= acpi_mac_passthru.o
 
 # IPMI may be used by other drivers, so it has to initialise before them
 obj-$(CONFIG_ACPI_IPMI)		+= acpi_ipmi.o
diff --git a/drivers/acpi/acpi_mac_passthru.c b/drivers/acpi/acpi_mac_passthru.c
new file mode 100644
index 000000000000..37d7e2388c0b
--- /dev/null
+++ b/drivers/acpi/acpi_mac_passthru.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * acpi_mac_passthru.c - ACPI MAC address pass through driver
+ *
+ *  Copyright (c) 2019 Dell Technology. All rights reserved.
+ *
+ * Search for MAC Address Pass Through information, and return the MAC address
+ * found.  This is set through enterprise policy settings, and expected to be
+ * read by ethernet drivers that have software programmable MAC addresses.
+ * Failure to find the needed information results in -ENODEV.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <acpi/acpi_mac_passthru.h>
+#include <linux/etherdevice.h>
+
+ACPI_MODULE_NAME("mapt");
+
+MODULE_AUTHOR("Charles Hyde");
+MODULE_DESCRIPTION("ACPI MAPT Driver");
+MODULE_LICENSE("GPL");
+
+int get_acpi_mac_passthru(char *macAddress)
+{
+	acpi_status status;
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	int ret = -EINVAL;
+	unsigned char buf[6];
+
+	/* returns _AUXMAC_#AABBCCDDEEFF# */
+	status = acpi_evaluate_object(NULL, "\\_SB.AMAC", NULL, &buffer);
+	obj = (union acpi_object *)buffer.pointer;
+	if (!ACPI_SUCCESS(status))
+		return -ENODEV;
+	if (obj->type != ACPI_TYPE_BUFFER || obj->string.length != 0x17) {
+		acpi_info("Invalid buffer for pass-thru MAC addr: (%d, %d)\n",
+			  obj->type, obj->string.length);
+		goto amacout;
+	}
+	if (strncmp(obj->string.pointer, "_AUXMAC_#", 9) != 0 ||
+	    strncmp(obj->string.pointer + 0x15, "#", 1) != 0) {
+		acpi_info("Invalid header when reading pass-thru MAC addr\n");
+		goto amacout;
+	}
+	ret = hex2bin(buf, obj->string.pointer + 9, 6);
+	if (!(ret == 0 && is_valid_ether_addr(buf))) {
+		acpi_info("Invalid MAC for pass-thru MAC addr: %d, %pM\n",
+			  ret, buf);
+		ret = -EINVAL;
+		goto amacout;
+	}
+	memcpy(macAddress, buf, 6);
+	acpi_info("Pass-thru MAC addr %pM\n", macAddress);
+
+amacout:
+	kfree(obj);
+	return ret;
+
+}
+EXPORT_SYMBOL_GPL(get_acpi_mac_passthru);
diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 04137ac373b0..6b9de6ae6524 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -23,6 +23,7 @@
 #include <linux/usb/cdc.h>
 #include <linux/suspend.h>
 #include <linux/acpi.h>
+#include <acpi/acpi_mac_passthru.h>
 
 /* Information for net-next */
 #define NETNEXT_VERSION		"09"
@@ -1178,12 +1179,7 @@ static int rtl8152_set_mac_address(struct net_device *netdev, void *p)
  */
 static int vendor_mac_passthru_addr_read(struct r8152 *tp, struct sockaddr *sa)
 {
-	acpi_status status;
-	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
-	union acpi_object *obj;
-	int ret = -EINVAL;
 	u32 ocp_data;
-	unsigned char buf[6];
 
 	/* test for -AD variant of RTL8153 */
 	ocp_data = ocp_read_word(tp, MCU_TYPE_USB, USB_MISC_0);
@@ -1204,39 +1200,7 @@ static int vendor_mac_passthru_addr_read(struct r8152 *tp, struct sockaddr *sa)
 			return -ENODEV;
 		}
 	}
-
-	/* returns _AUXMAC_#AABBCCDDEEFF# */
-	status = acpi_evaluate_object(NULL, "\\_SB.AMAC", NULL, &buffer);
-	obj = (union acpi_object *)buffer.pointer;
-	if (!ACPI_SUCCESS(status))
-		return -ENODEV;
-	if (obj->type != ACPI_TYPE_BUFFER || obj->string.length != 0x17) {
-		netif_warn(tp, probe, tp->netdev,
-			   "Invalid buffer for pass-thru MAC addr: (%d, %d)\n",
-			   obj->type, obj->string.length);
-		goto amacout;
-	}
-	if (strncmp(obj->string.pointer, "_AUXMAC_#", 9) != 0 ||
-	    strncmp(obj->string.pointer + 0x15, "#", 1) != 0) {
-		netif_warn(tp, probe, tp->netdev,
-			   "Invalid header when reading pass-thru MAC addr\n");
-		goto amacout;
-	}
-	ret = hex2bin(buf, obj->string.pointer + 9, 6);
-	if (!(ret == 0 && is_valid_ether_addr(buf))) {
-		netif_warn(tp, probe, tp->netdev,
-			   "Invalid MAC for pass-thru MAC addr: %d, %pM\n",
-			   ret, buf);
-		ret = -EINVAL;
-		goto amacout;
-	}
-	memcpy(sa->sa_data, buf, 6);
-	netif_info(tp, probe, tp->netdev,
-		   "Using pass-thru MAC addr %pM\n", sa->sa_data);
-
-amacout:
-	kfree(obj);
-	return ret;
+	return get_acpi_mac_passthru(sa->sa_data);
 }
 
 static int determine_ethernet_addr(struct r8152 *tp, struct sockaddr *sa)
@@ -4311,10 +4275,10 @@ static int rtl8152_post_reset(struct usb_interface *intf)
 	if (!tp)
 		return 0;
 
-	/* reset the MAC adddress in case of policy change */
+	/* reset the MAC address in case of policy change */
 	if (determine_ethernet_addr(tp, &sa) >= 0) {
 		rtnl_lock();
-		dev_set_mac_address (tp->netdev, &sa, NULL);
+		dev_set_mac_address(tp->netdev, &sa, NULL);
 		rtnl_unlock();
 	}
 
diff --git a/include/acpi/acpi_mac_passthru.h b/include/acpi/acpi_mac_passthru.h
new file mode 100644
index 000000000000..79c7a2d1062e
--- /dev/null
+++ b/include/acpi/acpi_mac_passthru.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * acpi_mac_passthru.h - ACPI MAC address pass through driver
+ *
+ *  Copyright (c) 2019 Dell Technology. All rights reserved.
+ *
+ * Search for MAC Address Pass Through information, and return the MAC address
+ * found.  This is set through enterprise policy settings, and expected to be
+ * read by ethernet drivers that have software programmable MAC addresses.
+ * Failure to find the needed information results in -ENODEV.
+ */
+
+#include <linux/module.h>
+#include <linux/acpi.h>
+
+#ifdef CONFIG_ACPI
+
+int get_acpi_mac_passthru(char *macAddress);
+
+#else
+
+static inline int get_acpi_mac_passthru(char *macAddress)
+{
+	return -ENODEV;
+}
+
+#endif
-- 
2.20.1