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, 568 insertions, 0 deletions

diff --git a/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
new file mode 100644
index 000000000..cf670e891
--- /dev/null
+++ b/drivers/char/ipmi/kcs_bmc_cdev_ipmi.c
@@ -0,0 +1,568 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2015-2018, Intel Corporation.
+ */
+
+#define pr_fmt(fmt) "kcs-bmc: " fmt
+
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/ipmi_bmc.h>
+#include <linux/list.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+
+#include "kcs_bmc_client.h"
+
+/* Different phases of the KCS BMC module.
+ *  KCS_PHASE_IDLE:
+ *            BMC should not be expecting nor sending any data.
+ *  KCS_PHASE_WRITE_START:
+ *            BMC is receiving a WRITE_START command from system software.
+ *  KCS_PHASE_WRITE_DATA:
+ *            BMC is receiving a data byte from system software.
+ *  KCS_PHASE_WRITE_END_CMD:
+ *            BMC is waiting a last data byte from system software.
+ *  KCS_PHASE_WRITE_DONE:
+ *            BMC has received the whole request from system software.
+ *  KCS_PHASE_WAIT_READ:
+ *            BMC is waiting the response from the upper IPMI service.
+ *  KCS_PHASE_READ:
+ *            BMC is transferring the response to system software.
+ *  KCS_PHASE_ABORT_ERROR1:
+ *            BMC is waiting error status request from system software.
+ *  KCS_PHASE_ABORT_ERROR2:
+ *            BMC is waiting for idle status afer error from system software.
+ *  KCS_PHASE_ERROR:
+ *            BMC has detected a protocol violation at the interface level.
+ */
+enum kcs_ipmi_phases {
+	KCS_PHASE_IDLE,
+
+	KCS_PHASE_WRITE_START,
+	KCS_PHASE_WRITE_DATA,
+	KCS_PHASE_WRITE_END_CMD,
+	KCS_PHASE_WRITE_DONE,
+
+	KCS_PHASE_WAIT_READ,
+	KCS_PHASE_READ,
+
+	KCS_PHASE_ABORT_ERROR1,
+	KCS_PHASE_ABORT_ERROR2,
+	KCS_PHASE_ERROR
+};
+
+/* IPMI 2.0 - Table 9-4, KCS Interface Status Codes */
+enum kcs_ipmi_errors {
+	KCS_NO_ERROR                = 0x00,
+	KCS_ABORTED_BY_COMMAND      = 0x01,
+	KCS_ILLEGAL_CONTROL_CODE    = 0x02,
+	KCS_LENGTH_ERROR            = 0x06,
+	KCS_UNSPECIFIED_ERROR       = 0xFF
+};
+
+struct kcs_bmc_ipmi {
+	struct list_head entry;
+
+	struct kcs_bmc_client client;
+
+	spinlock_t lock;
+
+	enum kcs_ipmi_phases phase;
+	enum kcs_ipmi_errors error;
+
+	wait_queue_head_t queue;
+	bool data_in_avail;
+	int  data_in_idx;
+	u8  *data_in;
+
+	int  data_out_idx;
+	int  data_out_len;
+	u8  *data_out;
+
+	struct mutex mutex;
+	u8 *kbuffer;
+
+	struct miscdevice miscdev;
+};
+
+#define DEVICE_NAME "ipmi-kcs"
+
+#define KCS_MSG_BUFSIZ    1000
+
+#define KCS_ZERO_DATA     0
+
+/* IPMI 2.0 - Table 9-1, KCS Interface Status Register Bits */
+#define KCS_STATUS_STATE(state) (state << 6)
+#define KCS_STATUS_STATE_MASK   GENMASK(7, 6)
+#define KCS_STATUS_CMD_DAT      BIT(3)
+#define KCS_STATUS_SMS_ATN      BIT(2)
+#define KCS_STATUS_IBF          BIT(1)
+#define KCS_STATUS_OBF          BIT(0)
+
+/* IPMI 2.0 - Table 9-2, KCS Interface State Bits */
+enum kcs_states {
+	IDLE_STATE  = 0,
+	READ_STATE  = 1,
+	WRITE_STATE = 2,
+	ERROR_STATE = 3,
+};
+
+/* IPMI 2.0 - Table 9-3, KCS Interface Control Codes */
+#define KCS_CMD_GET_STATUS_ABORT  0x60
+#define KCS_CMD_WRITE_START       0x61
+#define KCS_CMD_WRITE_END         0x62
+#define KCS_CMD_READ_BYTE         0x68
+
+static inline void set_state(struct kcs_bmc_ipmi *priv, u8 state)
+{
+	kcs_bmc_update_status(priv->client.dev, KCS_STATUS_STATE_MASK, KCS_STATUS_STATE(state));
+}
+
+static void kcs_bmc_ipmi_force_abort(struct kcs_bmc_ipmi *priv)
+{
+	set_state(priv, ERROR_STATE);
+	kcs_bmc_read_data(priv->client.dev);
+	kcs_bmc_write_data(priv->client.dev, KCS_ZERO_DATA);
+
+	priv->phase = KCS_PHASE_ERROR;
+	priv->data_in_avail = false;
+	priv->data_in_idx = 0;
+}
+
+static void kcs_bmc_ipmi_handle_data(struct kcs_bmc_ipmi *priv)
+{
+	struct kcs_bmc_device *dev;
+	u8 data;
+
+	dev = priv->client.dev;
+
+	switch (priv->phase) {
+	case KCS_PHASE_WRITE_START:
+		priv->phase = KCS_PHASE_WRITE_DATA;
+		fallthrough;
+
+	case KCS_PHASE_WRITE_DATA:
+		if (priv->data_in_idx < KCS_MSG_BUFSIZ) {
+			set_state(priv, WRITE_STATE);
+			kcs_bmc_write_data(dev, KCS_ZERO_DATA);
+			priv->data_in[priv->data_in_idx++] = kcs_bmc_read_data(dev);
+		} else {
+			kcs_bmc_ipmi_force_abort(priv);
+			priv->error = KCS_LENGTH_ERROR;
+		}
+		break;
+
+	case KCS_PHASE_WRITE_END_CMD:
+		if (priv->data_in_idx < KCS_MSG_BUFSIZ) {
+			set_state(priv, READ_STATE);
+			priv->data_in[priv->data_in_idx++] = kcs_bmc_read_data(dev);
+			priv->phase = KCS_PHASE_WRITE_DONE;
+			priv->data_in_avail = true;
+			wake_up_interruptible(&priv->queue);
+		} else {
+			kcs_bmc_ipmi_force_abort(priv);
+			priv->error = KCS_LENGTH_ERROR;
+		}
+		break;
+
+	case KCS_PHASE_READ:
+		if (priv->data_out_idx == priv->data_out_len)
+			set_state(priv, IDLE_STATE);
+
+		data = kcs_bmc_read_data(dev);
+		if (data != KCS_CMD_READ_BYTE) {
+			set_state(priv, ERROR_STATE);
+			kcs_bmc_write_data(dev, KCS_ZERO_DATA);
+			break;
+		}
+
+		if (priv->data_out_idx == priv->data_out_len) {
+			kcs_bmc_write_data(dev, KCS_ZERO_DATA);
+			priv->phase = KCS_PHASE_IDLE;
+			break;
+		}
+
+		kcs_bmc_write_data(dev, priv->data_out[priv->data_out_idx++]);
+		break;
+
+	case KCS_PHASE_ABORT_ERROR1:
+		set_state(priv, READ_STATE);
+		kcs_bmc_read_data(dev);
+		kcs_bmc_write_data(dev, priv->error);
+		priv->phase = KCS_PHASE_ABORT_ERROR2;
+		break;
+
+	case KCS_PHASE_ABORT_ERROR2:
+		set_state(priv, IDLE_STATE);
+		kcs_bmc_read_data(dev);
+		kcs_bmc_write_data(dev, KCS_ZERO_DATA);
+		priv->phase = KCS_PHASE_IDLE;
+		break;
+
+	default:
+		kcs_bmc_ipmi_force_abort(priv);
+		break;
+	}
+}
+
+static void kcs_bmc_ipmi_handle_cmd(struct kcs_bmc_ipmi *priv)
+{
+	u8 cmd;
+
+	set_state(priv, WRITE_STATE);
+	kcs_bmc_write_data(priv->client.dev, KCS_ZERO_DATA);
+
+	cmd = kcs_bmc_read_data(priv->client.dev);
+	switch (cmd) {
+	case KCS_CMD_WRITE_START:
+		priv->phase = KCS_PHASE_WRITE_START;
+		priv->error = KCS_NO_ERROR;
+		priv->data_in_avail = false;
+		priv->data_in_idx = 0;
+		break;
+
+	case KCS_CMD_WRITE_END:
+		if (priv->phase != KCS_PHASE_WRITE_DATA) {
+			kcs_bmc_ipmi_force_abort(priv);
+			break;
+		}
+
+		priv->phase = KCS_PHASE_WRITE_END_CMD;
+		break;
+
+	case KCS_CMD_GET_STATUS_ABORT:
+		if (priv->error == KCS_NO_ERROR)
+			priv->error = KCS_ABORTED_BY_COMMAND;
+
+		priv->phase = KCS_PHASE_ABORT_ERROR1;
+		priv->data_in_avail = false;
+		priv->data_in_idx = 0;
+		break;
+
+	default:
+		kcs_bmc_ipmi_force_abort(priv);
+		priv->error = KCS_ILLEGAL_CONTROL_CODE;
+		break;
+	}
+}
+
+static inline struct kcs_bmc_ipmi *client_to_kcs_bmc_ipmi(struct kcs_bmc_client *client)
+{
+	return container_of(client, struct kcs_bmc_ipmi, client);
+}
+
+static irqreturn_t kcs_bmc_ipmi_event(struct kcs_bmc_client *client)
+{
+	struct kcs_bmc_ipmi *priv;
+	u8 status;
+	int ret;
+
+	priv = client_to_kcs_bmc_ipmi(client);
+	if (!priv)
+		return IRQ_NONE;
+
+	spin_lock(&priv->lock);
+
+	status = kcs_bmc_read_status(client->dev);
+	if (status & KCS_STATUS_IBF) {
+		if (status & KCS_STATUS_CMD_DAT)
+			kcs_bmc_ipmi_handle_cmd(priv);
+		else
+			kcs_bmc_ipmi_handle_data(priv);
+
+		ret = IRQ_HANDLED;
+	} else {
+		ret = IRQ_NONE;
+	}
+
+	spin_unlock(&priv->lock);
+
+	return ret;
+}
+
+static const struct kcs_bmc_client_ops kcs_bmc_ipmi_client_ops = {
+	.event = kcs_bmc_ipmi_event,
+};
+
+static inline struct kcs_bmc_ipmi *to_kcs_bmc(struct file *filp)
+{
+	return container_of(filp->private_data, struct kcs_bmc_ipmi, miscdev);
+}
+
+static int kcs_bmc_ipmi_open(struct inode *inode, struct file *filp)
+{
+	struct kcs_bmc_ipmi *priv = to_kcs_bmc(filp);
+
+	return kcs_bmc_enable_device(priv->client.dev, &priv->client);
+}
+
+static __poll_t kcs_bmc_ipmi_poll(struct file *filp, poll_table *wait)
+{
+	struct kcs_bmc_ipmi *priv = to_kcs_bmc(filp);
+	__poll_t mask = 0;
+
+	poll_wait(filp, &priv->queue, wait);
+
+	spin_lock_irq(&priv->lock);
+	if (priv->data_in_avail)
+		mask |= EPOLLIN;
+	spin_unlock_irq(&priv->lock);
+
+	return mask;
+}
+
+static ssize_t kcs_bmc_ipmi_read(struct file *filp, char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	struct kcs_bmc_ipmi *priv = to_kcs_bmc(filp);
+	bool data_avail;
+	size_t data_len;
+	ssize_t ret;
+
+	if (!(filp->f_flags & O_NONBLOCK))
+		wait_event_interruptible(priv->queue,
+					 priv->data_in_avail);
+
+	mutex_lock(&priv->mutex);
+
+	spin_lock_irq(&priv->lock);
+	data_avail = priv->data_in_avail;
+	if (data_avail) {
+		data_len = priv->data_in_idx;
+		memcpy(priv->kbuffer, priv->data_in, data_len);
+	}
+	spin_unlock_irq(&priv->lock);
+
+	if (!data_avail) {
+		ret = -EAGAIN;
+		goto out_unlock;
+	}
+
+	if (count < data_len) {
+		pr_err("channel=%u with too large data : %zu\n",
+			priv->client.dev->channel, data_len);
+
+		spin_lock_irq(&priv->lock);
+		kcs_bmc_ipmi_force_abort(priv);
+		spin_unlock_irq(&priv->lock);
+
+		ret = -EOVERFLOW;
+		goto out_unlock;
+	}
+
+	if (copy_to_user(buf, priv->kbuffer, data_len)) {
+		ret = -EFAULT;
+		goto out_unlock;
+	}
+
+	ret = data_len;
+
+	spin_lock_irq(&priv->lock);
+	if (priv->phase == KCS_PHASE_WRITE_DONE) {
+		priv->phase = KCS_PHASE_WAIT_READ;
+		priv->data_in_avail = false;
+		priv->data_in_idx = 0;
+	} else {
+		ret = -EAGAIN;
+	}
+	spin_unlock_irq(&priv->lock);
+
+out_unlock:
+	mutex_unlock(&priv->mutex);
+
+	return ret;
+}
+
+static ssize_t kcs_bmc_ipmi_write(struct file *filp, const char __user *buf,
+			     size_t count, loff_t *ppos)
+{
+	struct kcs_bmc_ipmi *priv = to_kcs_bmc(filp);
+	ssize_t ret;
+
+	/* a minimum response size '3' : netfn + cmd + ccode */
+	if (count < 3 || count > KCS_MSG_BUFSIZ)
+		return -EINVAL;
+
+	mutex_lock(&priv->mutex);
+
+	if (copy_from_user(priv->kbuffer, buf, count)) {
+		ret = -EFAULT;
+		goto out_unlock;
+	}
+
+	spin_lock_irq(&priv->lock);
+	if (priv->phase == KCS_PHASE_WAIT_READ) {
+		priv->phase = KCS_PHASE_READ;
+		priv->data_out_idx = 1;
+		priv->data_out_len = count;
+		memcpy(priv->data_out, priv->kbuffer, count);
+		kcs_bmc_write_data(priv->client.dev, priv->data_out[0]);
+		ret = count;
+	} else {
+		ret = -EINVAL;
+	}
+	spin_unlock_irq(&priv->lock);
+
+out_unlock:
+	mutex_unlock(&priv->mutex);
+
+	return ret;
+}
+
+static long kcs_bmc_ipmi_ioctl(struct file *filp, unsigned int cmd,
+			  unsigned long arg)
+{
+	struct kcs_bmc_ipmi *priv = to_kcs_bmc(filp);
+	long ret = 0;
+
+	spin_lock_irq(&priv->lock);
+
+	switch (cmd) {
+	case IPMI_BMC_IOCTL_SET_SMS_ATN:
+		kcs_bmc_update_status(priv->client.dev, KCS_STATUS_SMS_ATN, KCS_STATUS_SMS_ATN);
+		break;
+
+	case IPMI_BMC_IOCTL_CLEAR_SMS_ATN:
+		kcs_bmc_update_status(priv->client.dev, KCS_STATUS_SMS_ATN, 0);
+		break;
+
+	case IPMI_BMC_IOCTL_FORCE_ABORT:
+		kcs_bmc_ipmi_force_abort(priv);
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	spin_unlock_irq(&priv->lock);
+
+	return ret;
+}
+
+static int kcs_bmc_ipmi_release(struct inode *inode, struct file *filp)
+{
+	struct kcs_bmc_ipmi *priv = to_kcs_bmc(filp);
+
+	kcs_bmc_ipmi_force_abort(priv);
+	kcs_bmc_disable_device(priv->client.dev, &priv->client);
+
+	return 0;
+}
+
+static const struct file_operations kcs_bmc_ipmi_fops = {
+	.owner          = THIS_MODULE,
+	.open           = kcs_bmc_ipmi_open,
+	.read           = kcs_bmc_ipmi_read,
+	.write          = kcs_bmc_ipmi_write,
+	.release        = kcs_bmc_ipmi_release,
+	.poll           = kcs_bmc_ipmi_poll,
+	.unlocked_ioctl = kcs_bmc_ipmi_ioctl,
+};
+
+static DEFINE_SPINLOCK(kcs_bmc_ipmi_instances_lock);
+static LIST_HEAD(kcs_bmc_ipmi_instances);
+
+static int kcs_bmc_ipmi_add_device(struct kcs_bmc_device *kcs_bmc)
+{
+	struct kcs_bmc_ipmi *priv;
+	int rc;
+
+	priv = devm_kzalloc(kcs_bmc->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	spin_lock_init(&priv->lock);
+	mutex_init(&priv->mutex);
+
+	init_waitqueue_head(&priv->queue);
+
+	priv->client.dev = kcs_bmc;
+	priv->client.ops = &kcs_bmc_ipmi_client_ops;
+	priv->data_in = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+	priv->data_out = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+	priv->kbuffer = devm_kmalloc(kcs_bmc->dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+
+	priv->miscdev.minor = MISC_DYNAMIC_MINOR;
+	priv->miscdev.name = devm_kasprintf(kcs_bmc->dev, GFP_KERNEL, "%s%u", DEVICE_NAME,
+					   kcs_bmc->channel);
+	if (!priv->data_in || !priv->data_out || !priv->kbuffer || !priv->miscdev.name)
+		return -EINVAL;
+
+	priv->miscdev.fops = &kcs_bmc_ipmi_fops;
+
+	rc = misc_register(&priv->miscdev);
+	if (rc) {
+		dev_err(kcs_bmc->dev, "Unable to register device: %d\n", rc);
+		return rc;
+	}
+
+	spin_lock_irq(&kcs_bmc_ipmi_instances_lock);
+	list_add(&priv->entry, &kcs_bmc_ipmi_instances);
+	spin_unlock_irq(&kcs_bmc_ipmi_instances_lock);
+
+	dev_info(kcs_bmc->dev, "Initialised IPMI client for channel %d", kcs_bmc->channel);
+
+	return 0;
+}
+
+static int kcs_bmc_ipmi_remove_device(struct kcs_bmc_device *kcs_bmc)
+{
+	struct kcs_bmc_ipmi *priv = NULL, *pos;
+
+	spin_lock_irq(&kcs_bmc_ipmi_instances_lock);
+	list_for_each_entry(pos, &kcs_bmc_ipmi_instances, entry) {
+		if (pos->client.dev == kcs_bmc) {
+			priv = pos;
+			list_del(&pos->entry);
+			break;
+		}
+	}
+	spin_unlock_irq(&kcs_bmc_ipmi_instances_lock);
+
+	if (!priv)
+		return -ENODEV;
+
+	misc_deregister(&priv->miscdev);
+	kcs_bmc_disable_device(priv->client.dev, &priv->client);
+	devm_kfree(kcs_bmc->dev, priv->kbuffer);
+	devm_kfree(kcs_bmc->dev, priv->data_out);
+	devm_kfree(kcs_bmc->dev, priv->data_in);
+	devm_kfree(kcs_bmc->dev, priv);
+
+	return 0;
+}
+
+static const struct kcs_bmc_driver_ops kcs_bmc_ipmi_driver_ops = {
+	.add_device = kcs_bmc_ipmi_add_device,
+	.remove_device = kcs_bmc_ipmi_remove_device,
+};
+
+static struct kcs_bmc_driver kcs_bmc_ipmi_driver = {
+	.ops = &kcs_bmc_ipmi_driver_ops,
+};
+
+static int __init kcs_bmc_ipmi_init(void)
+{
+	kcs_bmc_register_driver(&kcs_bmc_ipmi_driver);
+
+	return 0;
+}
+module_init(kcs_bmc_ipmi_init);
+
+static void __exit kcs_bmc_ipmi_exit(void)
+{
+	kcs_bmc_unregister_driver(&kcs_bmc_ipmi_driver);
+}
+module_exit(kcs_bmc_ipmi_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
+MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
+MODULE_DESCRIPTION("KCS BMC to handle the IPMI request from system software");