[PATCH v6 RESEND] r8152: Add support for setting pass through MAC address on RTL8153-AD

Subsystems: networking drivers, the rest, usb networking drivers

STALE3679d

5 messages, 3 authors, 2016-07-13 · open the first message on its own page

[PATCH v6 RESEND] r8152: Add support for setting pass through MAC address on RTL8153-AD

From: Mario Limonciello <hidden>
Date: 2016-07-12 00:58:20

The RTL8153-AD supports a persistent system specific MAC address.
This means a device plugged into two different systems with host side
support will show different (but persistent) MAC addresses.

This information for the system's persistent MAC address is burned in when
the system HW is built and available under \_SB.AMAC in the DSDT at runtime.

This technology is currently implemented in the Dell TB15 and WD15 Type-C
docks.  More information is available here:
http://www.dell.com/support/article/us/en/04/SLN301147

Signed-off-by: Mario Limonciello <redacted>
---
 drivers/net/usb/r8152.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 74 insertions(+), 2 deletions(-)
diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 0da72d3..2298f26 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -26,6 +26,7 @@
 #include <linux/mdio.h>
 #include <linux/usb/cdc.h>
 #include <linux/suspend.h>
+#include <linux/acpi.h>
 
 /* Information for net-next */
 #define NETNEXT_VERSION		"08"
@@ -460,6 +461,11 @@
 /* SRAM_IMPEDANCE */
 #define RX_DRIVING_MASK		0x6000
 
+/* MAC PASSTHRU */
+#define AD_MASK			0xfee0
+#define EFUSE			0xcfdb
+#define PASS_THRU_MASK		0x1
+
 enum rtl_register_content {
 	_1000bps	= 0x10,
 	_100bps		= 0x08,
@@ -1036,6 +1042,65 @@ out1:
 	return ret;
 }
 
+/* Devices containing RTL8153-AD can support a persistent
+ * host system provided MAC address.
+ * Examples of this are Dell TB15 and Dell WD15 docks
+ */
+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);
+	if ((ocp_data & AD_MASK) != 0x1000)
+		return -ENODEV;
+
+	/* test for MAC address pass-through bit */
+	ocp_data = ocp_read_byte(tp, MCU_TYPE_USB, EFUSE);
+	if ((ocp_data & PASS_THRU_MASK) != 1)
+		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 when reading 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 when reading pass-thru MAC addr: "
+			   "%d, %pM\n", ret, buf);
+		ret = -EINVAL;
+		goto amacout;
+	}
+	memcpy(sa->sa_data, buf, 6);
+	ether_addr_copy(tp->netdev->dev_addr, sa->sa_data);
+	netif_info(tp, probe, tp->netdev,
+		   "Using pass-thru MAC addr %pM\n", sa->sa_data);
+
+amacout:
+	kfree(obj);
+	return ret;
+}
+
 static int set_ethernet_addr(struct r8152 *tp)
 {
 	struct net_device *dev = tp->netdev;
@@ -1044,8 +1109,15 @@ static int set_ethernet_addr(struct r8152 *tp)
 
 	if (tp->version == RTL_VER_01)
 		ret = pla_ocp_read(tp, PLA_IDR, 8, sa.sa_data);
-	else
-		ret = pla_ocp_read(tp, PLA_BACKUP, 8, sa.sa_data);
+	else {
+		/* if this is not an RTL8153-AD, no eFuse mac pass thru set,
+		 * or system doesn't provide valid _SB.AMAC this will be
+		 * be expected to non-zero
+		 */
+		ret = vendor_mac_passthru_addr_read(tp, &sa);
+		if (ret < 0)
+			ret = pla_ocp_read(tp, PLA_BACKUP, 8, sa.sa_data);
+	}
 
 	if (ret < 0) {
 		netif_err(tp, probe, dev, "Get ether addr fail\n");
-- 
2.7.4

Re: [PATCH v6 RESEND] r8152: Add support for setting pass through MAC address on RTL8153-AD

From: David Miller <davem@davemloft.net>
Date: 2016-07-12 02:42:51

From: Mario Limonciello <redacted>
Date: Mon, 11 Jul 2016 19:58:04 -0500
The RTL8153-AD supports a persistent system specific MAC address.
This means a device plugged into two different systems with host side
support will show different (but persistent) MAC addresses.

This information for the system's persistent MAC address is burned in when
the system HW is built and available under \_SB.AMAC in the DSDT at runtime.

This technology is currently implemented in the Dell TB15 and WD15 Type-C
docks.  More information is available here:
http://www.dell.com/support/article/us/en/04/SLN301147

Signed-off-by: Mario Limonciello <redacted>
Applied.

Re: [PATCH v6 RESEND] r8152: Add support for setting pass through MAC address on RTL8153-AD

From: Michał Pecio <hidden>
Date: 2016-07-12 07:02:55

From: Mario Limonciello <redacted>
Date: Mon, 11 Jul 2016 19:58:04 -0500
quoted
The RTL8153-AD supports a persistent system specific MAC address.
This means a device plugged into two different systems with host
side support will show different (but persistent) MAC addresses.

This information for the system's persistent MAC address is burned
in when the system HW is built and available under \_SB.AMAC in the
DSDT at runtime.

This technology is currently implemented in the Dell TB15 and WD15
Type-C docks.  More information is available here:
http://www.dell.com/support/article/us/en/04/SLN301147

Signed-off-by: Mario Limonciello <redacted>  
Applied.
Hi,

Isn't it possible that the same ACPI name could be used for other
vendor-specific extensions on other laptops and that r8152 will now
wreak havoc there?

Regards,
MP

RE: [PATCH v6 RESEND] r8152: Add support for setting pass through MAC address on RTL8153-AD

From: <hidden>
Date: 2016-07-12 15:04:25

-----Original Message-----
From: Michał Pecio [mailto:michal.pecio@gmail.com]
Sent: Tuesday, July 12, 2016 2:03 AM
To: David Miller <davem@davemloft.net>
Cc: Limonciello, Mario <redacted>; linux-
kernel@vger.kernel.org; netdev@vger.kernel.org; linux-
usb@vger.kernel.org; anthony.wong@canonical.com
Subject: Re: [PATCH v6 RESEND] r8152: Add support for setting pass through
MAC address on RTL8153-AD
quoted
From: Mario Limonciello <redacted>
Date: Mon, 11 Jul 2016 19:58:04 -0500
quoted
The RTL8153-AD supports a persistent system specific MAC address.
This means a device plugged into two different systems with host
side support will show different (but persistent) MAC addresses.

This information for the system's persistent MAC address is burned
in when the system HW is built and available under \_SB.AMAC in the
DSDT at runtime.

This technology is currently implemented in the Dell TB15 and WD15
Type-C docks.  More information is available here:
http://www.dell.com/support/article/us/en/04/SLN301147

Signed-off-by: Mario Limonciello <redacted>
Applied.
Hi,

Isn't it possible that the same ACPI name could be used for other
vendor-specific extensions on other laptops and that r8152 will now
wreak havoc there?

Regards,
MP
This has been discussed a bit previously in earlier submissions.

In short, this is an extreme corner case.  Some changes were made 
to diminish potential impact. The ACPI code is resolved only when 
the specific variant of RTL8135 (-AD) has a bit set on the efuse.

The patch also explicitly checks the return type and contents of the
ACPI object and won't proceed if it's invalid.

The Type-C devices that provide this are currently only sold by Dell.  
This of course may change one day if other OEM's add this
feature, but it just shows that device scope is limited.

For now the way this is implemented if Realtek does choose to 
work with another OEM on this feature, there should be no
kernel code change necessary for interoperability of peripherals
on other OEM machines.

So in order to hit this hypothetical corner case today you would 
need to be using a real world type-C device something such as a 
Dell WD15 on another OEM's machine that has type-C and the exact
same ACPI object name that does $BADSTUFF other than return a
buffer.

If that situation arises please alert me and I'll send a follow up
patch that whitelists this to match DMI vendor of only Dell 
systems.

Re: [PATCH v6 RESEND] r8152: Add support for setting pass through MAC address on RTL8153-AD

From: Michał Pecio <hidden>
Date: 2016-07-13 06:24:24

So in order to hit this hypothetical corner case today you would 
need to be using a real world type-C device something such as a 
Dell WD15 on another OEM's machine that has type-C and the exact
same ACPI object name that does $BADSTUFF other than return a
buffer.
Exactly what I meant.
 
If that situation arises please alert me and I'll send a follow up
patch that whitelists this to match DMI vendor of only Dell 
systems.
I'm not sure if it's the most responsible way to approach this problem.
There were cases of laptops bricking (as in - they would never power on
ever again) just because Linux made some bad BIOS/ACPI calls. Also, see
the famous Samsung UEFI NVRAM fiasco or the recent pains with EFIVARS.

Regards,
MP
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