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

[<Charles.Hyde@dellteam.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: Realtek linux nic maintainers <nic_swsd@realtek.com>
Cc: linux-usb@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
---
 drivers/net/usb/r8152.c          | 44 +++--------------------
 include/acpi/acpi_mac_passthru.h | 16 +++++++++
 lib/Makefile                     |  3 +-
 lib/acpi_mac_passthru.c          | 61 ++++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+), 41 deletions(-)
 create mode 100644 include/acpi/acpi_mac_passthru.h
 create mode 100644 lib/acpi_mac_passthru.c

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 0cc03a9ff545..b1dba3400b74 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"
@@ -1175,12 +1176,7 @@ 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);
@@ -1201,39 +1197,7 @@ 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(&tp->intf->dev, sa);
 }
 
 static int determine_ethernet_addr(struct r8152 *tp, struct sockaddr *sa)
@@ -4309,10 +4273,10 @@ 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..fb2b114c2765
--- /dev/null
+++ b/include/acpi/acpi_mac_passthru.h
@@ -0,0 +1,16 @@
+/*
+ *  Copyright (c) 2019 Dell Technology. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/acpi.h>
+#include <linux/socket.h>
+
+int get_acpi_mac_passthru(struct device *dev, struct sockaddr *sa);
+
diff --git a/lib/Makefile b/lib/Makefile
index 29c02a924973..a902bec0ac65 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -35,7 +35,8 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 flex_proportions.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
 	 earlycpio.o seq_buf.o siphash.o dec_and_lock.o \
-	 nmi_backtrace.o nodemask.o win_minmax.o memcat_p.o
+	 nmi_backtrace.o nodemask.o win_minmax.o memcat_p.o \
+	 acpi_mac_passthru.o
 
 lib-$(CONFIG_PRINTK) += dump_stack.o
 lib-$(CONFIG_MMU) += ioremap.o
diff --git a/lib/acpi_mac_passthru.c b/lib/acpi_mac_passthru.c
new file mode 100644
index 000000000000..832596433592
--- /dev/null
+++ b/lib/acpi_mac_passthru.c
@@ -0,0 +1,61 @@
+/*
+ *  Copyright (c) 2019 Dell Technology. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ */
+
+#include <acpi/acpi_mac_passthru.h>
+#include <linux/etherdevice.h>
+
+int get_acpi_mac_passthru(struct device *dev, struct sockaddr *sa)
+{
+#ifdef CONFIG_ACPI
+	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) {
+		dev_warn(dev,
+			 "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) {
+		dev_warn(dev,
+			 "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))) {
+		dev_warn(dev,
+			 "Invalid MAC for pass-thru MAC addr: %d, %pM\n",
+			 ret, buf);
+		ret = -EINVAL;
+		goto amacout;
+	}
+	memcpy(sa->sa_data, buf, 6);
+	dev_info(dev, "Pass-thru MAC addr %pM\n", sa->sa_data);
+
+amacout:
+	kfree(obj);
+	return ret;
+
+#else	/* !CONFIG_ACPI */
+	(void)dev;
+	(void)sa;
+
+	return -ENODEV;
+#endif
+}
+EXPORT_SYMBOL_GPL(get_acpi_mac_passthru);
-- 
2.20.1