Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 533 insertions, 0 deletions

diff --git a/drivers/platform/surface/surface_aggregator_tabletsw.c b/drivers/platform/surface/surface_aggregator_tabletsw.c
new file mode 100644
index 000000000..9fed800c7
--- /dev/null
+++ b/drivers/platform/surface/surface_aggregator_tabletsw.c
@@ -0,0 +1,533 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Surface System Aggregator Module (SSAM) tablet mode switch driver.
+ *
+ * Copyright (C) 2022 Maximilian Luz <luzmaximilian@gmail.com>
+ */
+
+#include <asm/unaligned.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#include <linux/surface_aggregator/controller.h>
+#include <linux/surface_aggregator/device.h>
+
+
+/* -- SSAM generic tablet switch driver framework. -------------------------- */
+
+struct ssam_tablet_sw;
+
+struct ssam_tablet_sw_ops {
+	int (*get_state)(struct ssam_tablet_sw *sw, u32 *state);
+	const char *(*state_name)(struct ssam_tablet_sw *sw, u32 state);
+	bool (*state_is_tablet_mode)(struct ssam_tablet_sw *sw, u32 state);
+};
+
+struct ssam_tablet_sw {
+	struct ssam_device *sdev;
+
+	u32 state;
+	struct work_struct update_work;
+	struct input_dev *mode_switch;
+
+	struct ssam_tablet_sw_ops ops;
+	struct ssam_event_notifier notif;
+};
+
+struct ssam_tablet_sw_desc {
+	struct {
+		const char *name;
+		const char *phys;
+	} dev;
+
+	struct {
+		u32 (*notify)(struct ssam_event_notifier *nf, const struct ssam_event *event);
+		int (*get_state)(struct ssam_tablet_sw *sw, u32 *state);
+		const char *(*state_name)(struct ssam_tablet_sw *sw, u32 state);
+		bool (*state_is_tablet_mode)(struct ssam_tablet_sw *sw, u32 state);
+	} ops;
+
+	struct {
+		struct ssam_event_registry reg;
+		struct ssam_event_id id;
+		enum ssam_event_mask mask;
+		u8 flags;
+	} event;
+};
+
+static ssize_t state_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct ssam_tablet_sw *sw = dev_get_drvdata(dev);
+	const char *state = sw->ops.state_name(sw, sw->state);
+
+	return sysfs_emit(buf, "%s\n", state);
+}
+static DEVICE_ATTR_RO(state);
+
+static struct attribute *ssam_tablet_sw_attrs[] = {
+	&dev_attr_state.attr,
+	NULL,
+};
+
+static const struct attribute_group ssam_tablet_sw_group = {
+	.attrs = ssam_tablet_sw_attrs,
+};
+
+static void ssam_tablet_sw_update_workfn(struct work_struct *work)
+{
+	struct ssam_tablet_sw *sw = container_of(work, struct ssam_tablet_sw, update_work);
+	int tablet, status;
+	u32 state;
+
+	status = sw->ops.get_state(sw, &state);
+	if (status)
+		return;
+
+	if (sw->state == state)
+		return;
+	sw->state = state;
+
+	/* Send SW_TABLET_MODE event. */
+	tablet = sw->ops.state_is_tablet_mode(sw, state);
+	input_report_switch(sw->mode_switch, SW_TABLET_MODE, tablet);
+	input_sync(sw->mode_switch);
+}
+
+static int __maybe_unused ssam_tablet_sw_resume(struct device *dev)
+{
+	struct ssam_tablet_sw *sw = dev_get_drvdata(dev);
+
+	schedule_work(&sw->update_work);
+	return 0;
+}
+static SIMPLE_DEV_PM_OPS(ssam_tablet_sw_pm_ops, NULL, ssam_tablet_sw_resume);
+
+static int ssam_tablet_sw_probe(struct ssam_device *sdev)
+{
+	const struct ssam_tablet_sw_desc *desc;
+	struct ssam_tablet_sw *sw;
+	int tablet, status;
+
+	desc = ssam_device_get_match_data(sdev);
+	if (!desc) {
+		WARN(1, "no driver match data specified");
+		return -EINVAL;
+	}
+
+	sw = devm_kzalloc(&sdev->dev, sizeof(*sw), GFP_KERNEL);
+	if (!sw)
+		return -ENOMEM;
+
+	sw->sdev = sdev;
+
+	sw->ops.get_state = desc->ops.get_state;
+	sw->ops.state_name = desc->ops.state_name;
+	sw->ops.state_is_tablet_mode = desc->ops.state_is_tablet_mode;
+
+	INIT_WORK(&sw->update_work, ssam_tablet_sw_update_workfn);
+
+	ssam_device_set_drvdata(sdev, sw);
+
+	/* Get initial state. */
+	status = sw->ops.get_state(sw, &sw->state);
+	if (status)
+		return status;
+
+	/* Set up tablet mode switch. */
+	sw->mode_switch = devm_input_allocate_device(&sdev->dev);
+	if (!sw->mode_switch)
+		return -ENOMEM;
+
+	sw->mode_switch->name = desc->dev.name;
+	sw->mode_switch->phys = desc->dev.phys;
+	sw->mode_switch->id.bustype = BUS_HOST;
+	sw->mode_switch->dev.parent = &sdev->dev;
+
+	tablet = sw->ops.state_is_tablet_mode(sw, sw->state);
+	input_set_capability(sw->mode_switch, EV_SW, SW_TABLET_MODE);
+	input_report_switch(sw->mode_switch, SW_TABLET_MODE, tablet);
+
+	status = input_register_device(sw->mode_switch);
+	if (status)
+		return status;
+
+	/* Set up notifier. */
+	sw->notif.base.priority = 0;
+	sw->notif.base.fn = desc->ops.notify;
+	sw->notif.event.reg = desc->event.reg;
+	sw->notif.event.id = desc->event.id;
+	sw->notif.event.mask = desc->event.mask;
+	sw->notif.event.flags = SSAM_EVENT_SEQUENCED;
+
+	status = ssam_device_notifier_register(sdev, &sw->notif);
+	if (status)
+		return status;
+
+	status = sysfs_create_group(&sdev->dev.kobj, &ssam_tablet_sw_group);
+	if (status)
+		goto err;
+
+	/* We might have missed events during setup, so check again. */
+	schedule_work(&sw->update_work);
+	return 0;
+
+err:
+	ssam_device_notifier_unregister(sdev, &sw->notif);
+	cancel_work_sync(&sw->update_work);
+	return status;
+}
+
+static void ssam_tablet_sw_remove(struct ssam_device *sdev)
+{
+	struct ssam_tablet_sw *sw = ssam_device_get_drvdata(sdev);
+
+	sysfs_remove_group(&sdev->dev.kobj, &ssam_tablet_sw_group);
+
+	ssam_device_notifier_unregister(sdev, &sw->notif);
+	cancel_work_sync(&sw->update_work);
+}
+
+
+/* -- SSAM KIP tablet switch implementation. -------------------------------- */
+
+#define SSAM_EVENT_KIP_CID_COVER_STATE_CHANGED	0x1d
+
+enum ssam_kip_cover_state {
+	SSAM_KIP_COVER_STATE_DISCONNECTED  = 0x01,
+	SSAM_KIP_COVER_STATE_CLOSED        = 0x02,
+	SSAM_KIP_COVER_STATE_LAPTOP        = 0x03,
+	SSAM_KIP_COVER_STATE_FOLDED_CANVAS = 0x04,
+	SSAM_KIP_COVER_STATE_FOLDED_BACK   = 0x05,
+};
+
+static const char *ssam_kip_cover_state_name(struct ssam_tablet_sw *sw, u32 state)
+{
+	switch (state) {
+	case SSAM_KIP_COVER_STATE_DISCONNECTED:
+		return "disconnected";
+
+	case SSAM_KIP_COVER_STATE_CLOSED:
+		return "closed";
+
+	case SSAM_KIP_COVER_STATE_LAPTOP:
+		return "laptop";
+
+	case SSAM_KIP_COVER_STATE_FOLDED_CANVAS:
+		return "folded-canvas";
+
+	case SSAM_KIP_COVER_STATE_FOLDED_BACK:
+		return "folded-back";
+
+	default:
+		dev_warn(&sw->sdev->dev, "unknown KIP cover state: %u\n", state);
+		return "<unknown>";
+	}
+}
+
+static bool ssam_kip_cover_state_is_tablet_mode(struct ssam_tablet_sw *sw, u32 state)
+{
+	switch (state) {
+	case SSAM_KIP_COVER_STATE_DISCONNECTED:
+	case SSAM_KIP_COVER_STATE_FOLDED_CANVAS:
+	case SSAM_KIP_COVER_STATE_FOLDED_BACK:
+		return true;
+
+	case SSAM_KIP_COVER_STATE_CLOSED:
+	case SSAM_KIP_COVER_STATE_LAPTOP:
+		return false;
+
+	default:
+		dev_warn(&sw->sdev->dev, "unknown KIP cover state: %d\n", sw->state);
+		return true;
+	}
+}
+
+SSAM_DEFINE_SYNC_REQUEST_R(__ssam_kip_get_cover_state, u8, {
+	.target_category = SSAM_SSH_TC_KIP,
+	.target_id       = SSAM_SSH_TID_SAM,
+	.command_id      = 0x1d,
+	.instance_id     = 0x00,
+});
+
+static int ssam_kip_get_cover_state(struct ssam_tablet_sw *sw, u32 *state)
+{
+	int status;
+	u8 raw;
+
+	status = ssam_retry(__ssam_kip_get_cover_state, sw->sdev->ctrl, &raw);
+	if (status < 0) {
+		dev_err(&sw->sdev->dev, "failed to query KIP lid state: %d\n", status);
+		return status;
+	}
+
+	*state = raw;
+	return 0;
+}
+
+static u32 ssam_kip_sw_notif(struct ssam_event_notifier *nf, const struct ssam_event *event)
+{
+	struct ssam_tablet_sw *sw = container_of(nf, struct ssam_tablet_sw, notif);
+
+	if (event->command_id != SSAM_EVENT_KIP_CID_COVER_STATE_CHANGED)
+		return 0;	/* Return "unhandled". */
+
+	if (event->length < 1)
+		dev_warn(&sw->sdev->dev, "unexpected payload size: %u\n", event->length);
+
+	schedule_work(&sw->update_work);
+	return SSAM_NOTIF_HANDLED;
+}
+
+static const struct ssam_tablet_sw_desc ssam_kip_sw_desc = {
+	.dev = {
+		.name = "Microsoft Surface KIP Tablet Mode Switch",
+		.phys = "ssam/01:0e:01:00:01/input0",
+	},
+	.ops = {
+		.notify = ssam_kip_sw_notif,
+		.get_state = ssam_kip_get_cover_state,
+		.state_name = ssam_kip_cover_state_name,
+		.state_is_tablet_mode = ssam_kip_cover_state_is_tablet_mode,
+	},
+	.event = {
+		.reg = SSAM_EVENT_REGISTRY_SAM,
+		.id = {
+			.target_category = SSAM_SSH_TC_KIP,
+			.instance = 0,
+		},
+		.mask = SSAM_EVENT_MASK_TARGET,
+	},
+};
+
+
+/* -- SSAM POS tablet switch implementation. -------------------------------- */
+
+static bool tablet_mode_in_slate_state = true;
+module_param(tablet_mode_in_slate_state, bool, 0644);
+MODULE_PARM_DESC(tablet_mode_in_slate_state, "Enable tablet mode in slate device posture, default is 'true'");
+
+#define SSAM_EVENT_POS_CID_POSTURE_CHANGED	0x03
+#define SSAM_POS_MAX_SOURCES			4
+
+enum ssam_pos_state {
+	SSAM_POS_POSTURE_LID_CLOSED = 0x00,
+	SSAM_POS_POSTURE_LAPTOP     = 0x01,
+	SSAM_POS_POSTURE_SLATE      = 0x02,
+	SSAM_POS_POSTURE_TABLET     = 0x03,
+};
+
+struct ssam_sources_list {
+	__le32 count;
+	__le32 id[SSAM_POS_MAX_SOURCES];
+} __packed;
+
+static const char *ssam_pos_state_name(struct ssam_tablet_sw *sw, u32 state)
+{
+	switch (state) {
+	case SSAM_POS_POSTURE_LID_CLOSED:
+		return "closed";
+
+	case SSAM_POS_POSTURE_LAPTOP:
+		return "laptop";
+
+	case SSAM_POS_POSTURE_SLATE:
+		return "slate";
+
+	case SSAM_POS_POSTURE_TABLET:
+		return "tablet";
+
+	default:
+		dev_warn(&sw->sdev->dev, "unknown device posture: %u\n", state);
+		return "<unknown>";
+	}
+}
+
+static bool ssam_pos_state_is_tablet_mode(struct ssam_tablet_sw *sw, u32 state)
+{
+	switch (state) {
+	case SSAM_POS_POSTURE_LAPTOP:
+	case SSAM_POS_POSTURE_LID_CLOSED:
+		return false;
+
+	case SSAM_POS_POSTURE_SLATE:
+		return tablet_mode_in_slate_state;
+
+	case SSAM_POS_POSTURE_TABLET:
+		return true;
+
+	default:
+		dev_warn(&sw->sdev->dev, "unknown device posture: %u\n", state);
+		return true;
+	}
+}
+
+static int ssam_pos_get_sources_list(struct ssam_tablet_sw *sw, struct ssam_sources_list *sources)
+{
+	struct ssam_request rqst;
+	struct ssam_response rsp;
+	int status;
+
+	rqst.target_category = SSAM_SSH_TC_POS;
+	rqst.target_id = SSAM_SSH_TID_SAM;
+	rqst.command_id = 0x01;
+	rqst.instance_id = 0x00;
+	rqst.flags = SSAM_REQUEST_HAS_RESPONSE;
+	rqst.length = 0;
+	rqst.payload = NULL;
+
+	rsp.capacity = sizeof(*sources);
+	rsp.length = 0;
+	rsp.pointer = (u8 *)sources;
+
+	status = ssam_retry(ssam_request_do_sync_onstack, sw->sdev->ctrl, &rqst, &rsp, 0);
+	if (status)
+		return status;
+
+	/* We need at least the 'sources->count' field. */
+	if (rsp.length < sizeof(__le32)) {
+		dev_err(&sw->sdev->dev, "received source list response is too small\n");
+		return -EPROTO;
+	}
+
+	/* Make sure 'sources->count' matches with the response length. */
+	if (get_unaligned_le32(&sources->count) * sizeof(__le32) + sizeof(__le32) != rsp.length) {
+		dev_err(&sw->sdev->dev, "mismatch between number of sources and response size\n");
+		return -EPROTO;
+	}
+
+	return 0;
+}
+
+static int ssam_pos_get_source(struct ssam_tablet_sw *sw, u32 *source_id)
+{
+	struct ssam_sources_list sources = {};
+	int status;
+
+	status = ssam_pos_get_sources_list(sw, &sources);
+	if (status)
+		return status;
+
+	if (get_unaligned_le32(&sources.count) == 0) {
+		dev_err(&sw->sdev->dev, "no posture sources found\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * We currently don't know what to do with more than one posture
+	 * source. At the moment, only one source seems to be used/provided.
+	 * The WARN_ON() here should hopefully let us know quickly once there
+	 * is a device that provides multiple sources, at which point we can
+	 * then try to figure out how to handle them.
+	 */
+	WARN_ON(get_unaligned_le32(&sources.count) > 1);
+
+	*source_id = get_unaligned_le32(&sources.id[0]);
+	return 0;
+}
+
+SSAM_DEFINE_SYNC_REQUEST_WR(__ssam_pos_get_posture_for_source, __le32, __le32, {
+	.target_category = SSAM_SSH_TC_POS,
+	.target_id       = SSAM_SSH_TID_SAM,
+	.command_id      = 0x02,
+	.instance_id     = 0x00,
+});
+
+static int ssam_pos_get_posture_for_source(struct ssam_tablet_sw *sw, u32 source_id, u32 *posture)
+{
+	__le32 source_le = cpu_to_le32(source_id);
+	__le32 rspval_le = 0;
+	int status;
+
+	status = ssam_retry(__ssam_pos_get_posture_for_source, sw->sdev->ctrl,
+			    &source_le, &rspval_le);
+	if (status)
+		return status;
+
+	*posture = le32_to_cpu(rspval_le);
+	return 0;
+}
+
+static int ssam_pos_get_posture(struct ssam_tablet_sw *sw, u32 *state)
+{
+	u32 source_id;
+	int status;
+
+	status = ssam_pos_get_source(sw, &source_id);
+	if (status) {
+		dev_err(&sw->sdev->dev, "failed to get posture source ID: %d\n", status);
+		return status;
+	}
+
+	status = ssam_pos_get_posture_for_source(sw, source_id, state);
+	if (status) {
+		dev_err(&sw->sdev->dev, "failed to get posture value for source %u: %d\n",
+			source_id, status);
+		return status;
+	}
+
+	return 0;
+}
+
+static u32 ssam_pos_sw_notif(struct ssam_event_notifier *nf, const struct ssam_event *event)
+{
+	struct ssam_tablet_sw *sw = container_of(nf, struct ssam_tablet_sw, notif);
+
+	if (event->command_id != SSAM_EVENT_POS_CID_POSTURE_CHANGED)
+		return 0;	/* Return "unhandled". */
+
+	if (event->length != sizeof(__le32) * 3)
+		dev_warn(&sw->sdev->dev, "unexpected payload size: %u\n", event->length);
+
+	schedule_work(&sw->update_work);
+	return SSAM_NOTIF_HANDLED;
+}
+
+static const struct ssam_tablet_sw_desc ssam_pos_sw_desc = {
+	.dev = {
+		.name = "Microsoft Surface POS Tablet Mode Switch",
+		.phys = "ssam/01:26:01:00:01/input0",
+	},
+	.ops = {
+		.notify = ssam_pos_sw_notif,
+		.get_state = ssam_pos_get_posture,
+		.state_name = ssam_pos_state_name,
+		.state_is_tablet_mode = ssam_pos_state_is_tablet_mode,
+	},
+	.event = {
+		.reg = SSAM_EVENT_REGISTRY_SAM,
+		.id = {
+			.target_category = SSAM_SSH_TC_POS,
+			.instance = 0,
+		},
+		.mask = SSAM_EVENT_MASK_TARGET,
+	},
+};
+
+
+/* -- Driver registration. -------------------------------------------------- */
+
+static const struct ssam_device_id ssam_tablet_sw_match[] = {
+	{ SSAM_SDEV(KIP, SAM, 0x00, 0x01), (unsigned long)&ssam_kip_sw_desc },
+	{ SSAM_SDEV(POS, SAM, 0x00, 0x01), (unsigned long)&ssam_pos_sw_desc },
+	{ },
+};
+MODULE_DEVICE_TABLE(ssam, ssam_tablet_sw_match);
+
+static struct ssam_device_driver ssam_tablet_sw_driver = {
+	.probe = ssam_tablet_sw_probe,
+	.remove = ssam_tablet_sw_remove,
+	.match_table = ssam_tablet_sw_match,
+	.driver = {
+		.name = "surface_aggregator_tablet_mode_switch",
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.pm = &ssam_tablet_sw_pm_ops,
+	},
+};
+module_ssam_device_driver(ssam_tablet_sw_driver);
+
+MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
+MODULE_DESCRIPTION("Tablet mode switch driver for Surface devices using the Surface Aggregator Module");
+MODULE_LICENSE("GPL");