Merge tag 'for-linus-5.14-1' of git://github.com/cminyard/linux-ipmi

Pull IPMI driver updates from Corey Minyard:
 "Mostly a restructure of the kcs_bmc driver to make it easier to use
  with different types of devices, and just to clean things up and
  improve things.

  Also some bug fixes for the kcs_bmc driver.

  One fix to the IPMI watchdog to stop the timer when the action is
  none. Not a big deal, but it's the right thing to do"

* tag 'for-linus-5.14-1' of git://github.com/cminyard/linux-ipmi:
  ipmi: kcs_bmc_aspeed: Fix less than zero comparison of a unsigned int
  ipmi: kcs_bmc_aspeed: Optionally apply status address
  ipmi: kcs_bmc_aspeed: Fix IBFIE typo from datasheet
  ipmi: kcs_bmc_aspeed: Implement KCS SerIRQ configuration
  dt-bindings: ipmi: Add optional SerIRQ property to ASPEED KCS devices
  dt-bindings: ipmi: Convert ASPEED KCS binding to schema
  ipmi: kcs_bmc: Add serio adaptor
  ipmi: kcs_bmc: Enable IBF on open
  ipmi: kcs_bmc: Allow clients to control KCS IRQ state
  ipmi: kcs_bmc: Decouple the IPMI chardev from the core
  ipmi: kcs_bmc: Strip private client data from struct kcs_bmc
  ipmi: kcs_bmc: Split headers into device and client
  ipmi: kcs_bmc: Turn the driver data-structures inside-out
  ipmi: kcs_bmc: Split out kcs_bmc_cdev_ipmi
  ipmi: kcs_bmc: Rename {read,write}_{status,data}() functions
  ipmi: kcs_bmc: Make status update atomic
  ipmi: kcs_bmc_aspeed: Use of match data to extract KCS properties
  ipmi/watchdog: Stop watchdog timer when the current action is 'none'

Documentation/devicetree/bindings/ipmi/aspeed,ast2400-kcs-bmc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/ipmi/aspeed,ast2400-kcs-bmc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASPEED BMC KCS Devices
+
+maintainers:
+  - Andrew Jeffery <andrew@aj.id.au>
+
+description: |
+  The Aspeed BMC SoCs typically use the Keyboard-Controller-Style (KCS)
+  interfaces on the LPC bus for in-band IPMI communication with their host.
+
+properties:
+  compatible:
+    oneOf:
+      - description: Channel ID derived from reg
+        items:
+          enum:
+            - aspeed,ast2400-kcs-bmc-v2
+            - aspeed,ast2500-kcs-bmc-v2
+            - aspeed,ast2600-kcs-bmc
+
+      - description: Old-style with explicit channel ID, no reg
+        deprecated: true
+        items:
+          enum:
+            - aspeed,ast2400-kcs-bmc
+            - aspeed,ast2500-kcs-bmc
+
+  interrupts:
+    maxItems: 1
+
+  reg:
+    # maxItems: 3
+    items:
+      - description: IDR register
+      - description: ODR register
+      - description: STR register
+
+  aspeed,lpc-io-reg:
+    $ref: '/schemas/types.yaml#/definitions/uint32-array'
+    minItems: 1
+    maxItems: 2
+    description: |
+      The host CPU LPC IO data and status addresses for the device. For most
+      channels the status address is derived from the data address, but the
+      status address may be optionally provided.
+
+  aspeed,lpc-interrupts:
+    $ref: "/schemas/types.yaml#/definitions/uint32-array"
+    minItems: 2
+    maxItems: 2
+    description: |
+      A 2-cell property expressing the LPC SerIRQ number and the interrupt
+      level/sense encoding (specified in the standard fashion).
+
+      Note that the generated interrupt is issued from the BMC to the host, and
+      thus the target interrupt controller is not captured by the BMC's
+      devicetree.
+
+  kcs_chan:
+    deprecated: true
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    description: The LPC channel number in the controller
+
+  kcs_addr:
+    deprecated: true
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    description: The host CPU IO map address
+
+required:
+  - compatible
+  - interrupts
+
+additionalProperties: false
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - aspeed,ast2400-kcs-bmc
+              - aspeed,ast2500-kcs-bmc
+    then:
+      required:
+        - kcs_chan
+        - kcs_addr
+    else:
+      required:
+        - reg
+        - aspeed,lpc-io-reg
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    kcs3: kcs@24 {
+        compatible = "aspeed,ast2600-kcs-bmc";
+        reg = <0x24 0x1>, <0x30 0x1>, <0x3c 0x1>;
+        aspeed,lpc-io-reg = <0xca2>;
+        aspeed,lpc-interrupts = <11 IRQ_TYPE_LEVEL_LOW>;
+        interrupts = <8>;
+    };

Documentation/devicetree/bindings/ipmi/aspeed-kcs-bmc.txt

-# Aspeed KCS (Keyboard Controller Style) IPMI interface
-
-The Aspeed SOCs (AST2400 and AST2500) are commonly used as BMCs
-(Baseboard Management Controllers) and the KCS interface can be
-used to perform in-band IPMI communication with their host.
-
-## v1
-Required properties:
-- compatible : should be one of
-    "aspeed,ast2400-kcs-bmc"
-    "aspeed,ast2500-kcs-bmc"
-- interrupts : interrupt generated by the controller
-- kcs_chan : The LPC channel number in the controller
-- kcs_addr : The host CPU IO map address
-
-## v2
-Required properties:
-- compatible : should be one of
-    "aspeed,ast2400-kcs-bmc-v2"
-    "aspeed,ast2500-kcs-bmc-v2"
-- reg : The address and size of the IDR, ODR and STR registers
-- interrupts : interrupt generated by the controller
-- aspeed,lpc-io-reg : The host CPU LPC IO address for the device
-
-Example:
-
-    kcs3: kcs@24 {
-        compatible = "aspeed,ast2500-kcs-bmc-v2";
-        reg = <0x24 0x1>, <0x30 0x1>, <0x3c 0x1>;
-        aspeed,lpc-reg = <0xca2>;
-        interrupts = <8>;
-        status = "okay";
-    };

drivers/char/ipmi/Kconfig

@@ -124,6 +124,33 @@ config NPCM7XX_KCS_IPMI_BMC
 	  This support is also available as a module.  If so, the module
 	  will be called kcs_bmc_npcm7xx.
 
+config IPMI_KCS_BMC_CDEV_IPMI
+	depends on IPMI_KCS_BMC
+	tristate "IPMI character device interface for BMC KCS devices"
+	help
+	  Provides a BMC-side character device implementing IPMI
+	  semantics for KCS IPMI devices.
+
+	  Say YES if you wish to expose KCS devices on the BMC for IPMI
+	  purposes.
+
+	  This support is also available as a module. The module will be
+	  called kcs_bmc_cdev_ipmi.
+
+config IPMI_KCS_BMC_SERIO
+	depends on IPMI_KCS_BMC && SERIO
+	tristate "SerIO adaptor for BMC KCS devices"
+	help
+	  Adapts the BMC KCS device for the SerIO subsystem. This allows users
+	  to take advantage of userspace interfaces provided by SerIO where
+	  appropriate.
+
+	  Say YES if you wish to expose KCS devices on the BMC via SerIO
+	  interfaces.
+
+	  This support is also available as a module. The module will be
+	  called kcs_bmc_serio.
+
 config ASPEED_BT_IPMI_BMC
 	depends on ARCH_ASPEED || COMPILE_TEST
 	depends on REGMAP && REGMAP_MMIO && MFD_SYSCON

drivers/char/ipmi/Makefile

@@ -23,6 +23,8 @@ obj-$(CONFIG_IPMI_POWERNV) += ipmi_powernv.o
 obj-$(CONFIG_IPMI_WATCHDOG) += ipmi_watchdog.o
 obj-$(CONFIG_IPMI_POWEROFF) += ipmi_poweroff.o
 obj-$(CONFIG_IPMI_KCS_BMC) += kcs_bmc.o
+obj-$(CONFIG_IPMI_KCS_BMC_SERIO) += kcs_bmc_serio.o
+obj-$(CONFIG_IPMI_KCS_BMC_CDEV_IPMI) += kcs_bmc_cdev_ipmi.o
 obj-$(CONFIG_ASPEED_BT_IPMI_BMC) += bt-bmc.o
 obj-$(CONFIG_ASPEED_KCS_IPMI_BMC) += kcs_bmc_aspeed.o
 obj-$(CONFIG_NPCM7XX_KCS_IPMI_BMC) += kcs_bmc_npcm7xx.o

drivers/char/ipmi/ipmi_watchdog.c

@@ -371,17 +371,19 @@ static int __ipmi_set_timeout(struct ipmi_smi_msg  *smi_msg,
 	data[0] = 0;
 	WDOG_SET_TIMER_USE(data[0], WDOG_TIMER_USE_SMS_OS);
 
-	if ((ipmi_version_major > 1)
-	    || ((ipmi_version_major == 1) && (ipmi_version_minor >= 5))) {
+	if (ipmi_watchdog_state != WDOG_TIMEOUT_NONE) {
+		if ((ipmi_version_major > 1) ||
+		    ((ipmi_version_major == 1) && (ipmi_version_minor >= 5))) {
 			/* This is an IPMI 1.5-only feature. */
 			data[0] |= WDOG_DONT_STOP_ON_SET;
-	} else if (ipmi_watchdog_state != WDOG_TIMEOUT_NONE) {
+		} else {
 			/*
 			 * In ipmi 1.0, setting the timer stops the watchdog, we
 			 * need to start it back up again.
 			 */
 			hbnow = 1;
 		}
+	}
 
 	data[1] = 0;
 	WDOG_SET_TIMEOUT_ACT(data[1], ipmi_watchdog_state);

drivers/char/ipmi/kcs_bmc.h

@@ -6,54 +6,14 @@
 #ifndef __KCS_BMC_H__
 #define __KCS_BMC_H__
 
-#include <linux/miscdevice.h>
+#include <linux/list.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_phases {
-	KCS_PHASE_IDLE,
-
-	KCS_PHASE_WRITE_START,
-	KCS_PHASE_WRITE_DATA,
-	KCS_PHASE_WRITE_END_CMD,
-	KCS_PHASE_WRITE_DONE,
+#define KCS_BMC_EVENT_TYPE_OBE	BIT(0)
+#define KCS_BMC_EVENT_TYPE_IBF	BIT(1)
 
-	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_errors {
-	KCS_NO_ERROR                = 0x00,
-	KCS_ABORTED_BY_COMMAND      = 0x01,
-	KCS_ILLEGAL_CONTROL_CODE    = 0x02,
-	KCS_LENGTH_ERROR            = 0x06,
-	KCS_UNSPECIFIED_ERROR       = 0xFF
-};
+#define KCS_BMC_STR_OBF		BIT(0)
+#define KCS_BMC_STR_IBF		BIT(1)
+#define KCS_BMC_STR_CMD_DAT	BIT(3)
 
 /* IPMI 2.0 - 9.5, KCS Interface Registers
  * @idr: Input Data Register
@@ -66,43 +26,21 @@ struct kcs_ioreg {
 	u32 str;
 };
 
-struct kcs_bmc {
-	spinlock_t lock;
+struct kcs_bmc_device_ops;
+struct kcs_bmc_client;
 
+struct kcs_bmc_device {
+	struct list_head entry;
+
+	struct device *dev;
 	u32 channel;
-	int running;
 
-	/* Setup by BMC KCS controller driver */
 	struct kcs_ioreg ioreg;
-	u8 (*io_inputb)(struct kcs_bmc *kcs_bmc, u32 reg);
-	void (*io_outputb)(struct kcs_bmc *kcs_bmc, u32 reg, u8 b);
-
-	enum kcs_phases phase;
-	enum kcs_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;
+	const struct kcs_bmc_device_ops *ops;
 
-	struct miscdevice miscdev;
-
-	unsigned long priv[];
+	spinlock_t lock;
+	struct kcs_bmc_client *client;
 };
 
-static inline void *kcs_bmc_priv(struct kcs_bmc *kcs_bmc)
-{
-	return kcs_bmc->priv;
-}
-
-int kcs_bmc_handle_event(struct kcs_bmc *kcs_bmc);
-struct kcs_bmc *kcs_bmc_alloc(struct device *dev, int sizeof_priv,
-					u32 channel);
 #endif /* __KCS_BMC_H__ */

drivers/char/ipmi/kcs_bmc_client.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2021, IBM Corp. */
+
+#ifndef __KCS_BMC_CONSUMER_H__
+#define __KCS_BMC_CONSUMER_H__
+
+#include <linux/irqreturn.h>
+
+#include "kcs_bmc.h"
+
+struct kcs_bmc_driver_ops {
+	int (*add_device)(struct kcs_bmc_device *kcs_bmc);
+	int (*remove_device)(struct kcs_bmc_device *kcs_bmc);
+};
+
+struct kcs_bmc_driver {
+	struct list_head entry;
+
+	const struct kcs_bmc_driver_ops *ops;
+};
+
+struct kcs_bmc_client_ops {
+	irqreturn_t (*event)(struct kcs_bmc_client *client);
+};
+
+struct kcs_bmc_client {
+	const struct kcs_bmc_client_ops *ops;
+
+	struct kcs_bmc_device *dev;
+};
+
+void kcs_bmc_register_driver(struct kcs_bmc_driver *drv);
+void kcs_bmc_unregister_driver(struct kcs_bmc_driver *drv);
+
+int kcs_bmc_enable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client);
+void kcs_bmc_disable_device(struct kcs_bmc_device *kcs_bmc, struct kcs_bmc_client *client);
+
+void kcs_bmc_update_event_mask(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 events);
+
+u8 kcs_bmc_read_data(struct kcs_bmc_device *kcs_bmc);
+void kcs_bmc_write_data(struct kcs_bmc_device *kcs_bmc, u8 data);
+u8 kcs_bmc_read_status(struct kcs_bmc_device *kcs_bmc);
+void kcs_bmc_write_status(struct kcs_bmc_device *kcs_bmc, u8 data);
+void kcs_bmc_update_status(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 val);
+#endif

drivers/char/ipmi/kcs_bmc_device.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2021, IBM Corp. */
+
+#ifndef __KCS_BMC_DEVICE_H__
+#define __KCS_BMC_DEVICE_H__
+
+#include <linux/irqreturn.h>
+
+#include "kcs_bmc.h"
+
+struct kcs_bmc_device_ops {
+	void (*irq_mask_update)(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 enable);
+	u8 (*io_inputb)(struct kcs_bmc_device *kcs_bmc, u32 reg);
+	void (*io_outputb)(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 b);
+	void (*io_updateb)(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 mask, u8 b);
+};
+
+irqreturn_t kcs_bmc_handle_event(struct kcs_bmc_device *kcs_bmc);
+int kcs_bmc_add_device(struct kcs_bmc_device *kcs_bmc);
+void kcs_bmc_remove_device(struct kcs_bmc_device *kcs_bmc);
+
+#endif

drivers/char/ipmi/kcs_bmc_npcm7xx.c

@@ -17,7 +17,7 @@
 #include <linux/regmap.h>
 #include <linux/slab.h>
 
-#include "kcs_bmc.h"
+#include "kcs_bmc_device.h"
 
 #define DEVICE_NAME	"npcm-kcs-bmc"
 #define KCS_CHANNEL_MAX	3
@@ -38,6 +38,7 @@
 #define KCS2CTL		0x2A
 #define KCS3CTL		0x3C
 #define    KCS_CTL_IBFIE	BIT(0)
+#define    KCS_CTL_OBEIE	BIT(1)
 
 #define KCS1IE		0x1C
 #define KCS2IE		0x2E
@@ -65,6 +66,8 @@ struct npcm7xx_kcs_reg {
 };
 
 struct npcm7xx_kcs_bmc {
+	struct kcs_bmc_device kcs_bmc;
+
 	struct regmap *map;
 
 	const struct npcm7xx_kcs_reg *reg;
@@ -76,9 +79,14 @@ static const struct npcm7xx_kcs_reg npcm7xx_kcs_reg_tbl[KCS_CHANNEL_MAX] = {
 	{ .sts = KCS3ST, .dob = KCS3DO, .dib = KCS3DI, .ctl = KCS3CTL, .ie = KCS3IE },
 };
 
-static u8 npcm7xx_kcs_inb(struct kcs_bmc *kcs_bmc, u32 reg)
+static inline struct npcm7xx_kcs_bmc *to_npcm7xx_kcs_bmc(struct kcs_bmc_device *kcs_bmc)
+{
+	return container_of(kcs_bmc, struct npcm7xx_kcs_bmc, kcs_bmc);
+}
+
+static u8 npcm7xx_kcs_inb(struct kcs_bmc_device *kcs_bmc, u32 reg)
 {
-	struct npcm7xx_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
 	u32 val = 0;
 	int rc;
 
@@ -88,37 +96,53 @@ static u8 npcm7xx_kcs_inb(struct kcs_bmc *kcs_bmc, u32 reg)
 	return rc == 0 ? (u8)val : 0;
 }
 
-static void npcm7xx_kcs_outb(struct kcs_bmc *kcs_bmc, u32 reg, u8 data)
+static void npcm7xx_kcs_outb(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 data)
 {
-	struct npcm7xx_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
 	int rc;
 
 	rc = regmap_write(priv->map, reg, data);
 	WARN(rc != 0, "regmap_write() failed: %d\n", rc);
 }
 
-static void npcm7xx_kcs_enable_channel(struct kcs_bmc *kcs_bmc, bool enable)
+static void npcm7xx_kcs_updateb(struct kcs_bmc_device *kcs_bmc, u32 reg, u8 mask, u8 data)
 {
-	struct npcm7xx_kcs_bmc *priv = kcs_bmc_priv(kcs_bmc);
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
+	int rc;
 
-	regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_IBFIE,
-			   enable ? KCS_CTL_IBFIE : 0);
+	rc = regmap_update_bits(priv->map, reg, mask, data);
+	WARN(rc != 0, "regmap_update_bits() failed: %d\n", rc);
+}
+
+static void npcm7xx_kcs_enable_channel(struct kcs_bmc_device *kcs_bmc, bool enable)
+{
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
 
 	regmap_update_bits(priv->map, priv->reg->ie, KCS_IE_IRQE | KCS_IE_HIRQE,
 			   enable ? KCS_IE_IRQE | KCS_IE_HIRQE : 0);
 }
 
-static irqreturn_t npcm7xx_kcs_irq(int irq, void *arg)
+static void npcm7xx_kcs_irq_mask_update(struct kcs_bmc_device *kcs_bmc, u8 mask, u8 state)
 {
-	struct kcs_bmc *kcs_bmc = arg;
+	struct npcm7xx_kcs_bmc *priv = to_npcm7xx_kcs_bmc(kcs_bmc);
+
+	if (mask & KCS_BMC_EVENT_TYPE_OBE)
+		regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_OBEIE,
+				   !!(state & KCS_BMC_EVENT_TYPE_OBE) * KCS_CTL_OBEIE);
 
-	if (!kcs_bmc_handle_event(kcs_bmc))
-		return IRQ_HANDLED;
+	if (mask & KCS_BMC_EVENT_TYPE_IBF)
+		regmap_update_bits(priv->map, priv->reg->ctl, KCS_CTL_IBFIE,
+				   !!(state & KCS_BMC_EVENT_TYPE_IBF) * KCS_CTL_IBFIE);
+}
+
+static irqreturn_t npcm7xx_kcs_irq(int irq, void *arg)
+{
+	struct kcs_bmc_device *kcs_bmc = arg;
 
-	return IRQ_NONE;
+	return kcs_bmc_handle_event(kcs_bmc);
 }
 
-static int npcm7xx_kcs_config_irq(struct kcs_bmc *kcs_bmc,
+static int npcm7xx_kcs_config_irq(struct kcs_bmc_device *kcs_bmc,
 				  struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -132,11 +156,18 @@ static int npcm7xx_kcs_config_irq(struct kcs_bmc *kcs_bmc,
 				dev_name(dev), kcs_bmc);
 }
 
+static const struct kcs_bmc_device_ops npcm7xx_kcs_ops = {
+	.irq_mask_update = npcm7xx_kcs_irq_mask_update,
+	.io_inputb = npcm7xx_kcs_inb,
+	.io_outputb = npcm7xx_kcs_outb,
+	.io_updateb = npcm7xx_kcs_updateb,
+};
+
 static int npcm7xx_kcs_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct npcm7xx_kcs_bmc *priv;
-	struct kcs_bmc *kcs_bmc;
+	struct kcs_bmc_device *kcs_bmc;
 	u32 chan;
 	int rc;
 
@@ -146,11 +177,10 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
-	kcs_bmc = kcs_bmc_alloc(dev, sizeof(*priv), chan);
-	if (!kcs_bmc)
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
 		return -ENOMEM;
 
-	priv = kcs_bmc_priv(kcs_bmc);
 	priv->map = syscon_node_to_regmap(dev->parent->of_node);
 	if (IS_ERR(priv->map)) {
 		dev_err(dev, "Couldn't get regmap\n");
@@ -158,22 +188,26 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
 	}
 	priv->reg = &npcm7xx_kcs_reg_tbl[chan - 1];
 
+	kcs_bmc = &priv->kcs_bmc;
+	kcs_bmc->dev = &pdev->dev;
+	kcs_bmc->channel = chan;
 	kcs_bmc->ioreg.idr = priv->reg->dib;
 	kcs_bmc->ioreg.odr = priv->reg->dob;
 	kcs_bmc->ioreg.str = priv->reg->sts;
-	kcs_bmc->io_inputb = npcm7xx_kcs_inb;
-	kcs_bmc->io_outputb = npcm7xx_kcs_outb;
+	kcs_bmc->ops = &npcm7xx_kcs_ops;
 
-	dev_set_drvdata(dev, kcs_bmc);
+	platform_set_drvdata(pdev, priv);
 
-	npcm7xx_kcs_enable_channel(kcs_bmc, true);
 	rc = npcm7xx_kcs_config_irq(kcs_bmc, pdev);
 	if (rc)
 		return rc;
 
-	rc = misc_register(&kcs_bmc->miscdev);
+	npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0);
+	npcm7xx_kcs_enable_channel(kcs_bmc, true);
+
+	rc = kcs_bmc_add_device(kcs_bmc);
 	if (rc) {
-		dev_err(dev, "Unable to register device\n");
+		dev_warn(&pdev->dev, "Failed to register channel %d: %d\n", kcs_bmc->channel, rc);
 		return rc;
 	}
 
@@ -186,9 +220,13 @@ static int npcm7xx_kcs_probe(struct platform_device *pdev)
 
 static int npcm7xx_kcs_remove(struct platform_device *pdev)
 {
-	struct kcs_bmc *kcs_bmc = dev_get_drvdata(&pdev->dev);
+	struct npcm7xx_kcs_bmc *priv = platform_get_drvdata(pdev);
+	struct kcs_bmc_device *kcs_bmc = &priv->kcs_bmc;
+
+	kcs_bmc_remove_device(kcs_bmc);
 
-	misc_deregister(&kcs_bmc->miscdev);
+	npcm7xx_kcs_enable_channel(kcs_bmc, false);
+	npcm7xx_kcs_irq_mask_update(kcs_bmc, (KCS_BMC_EVENT_TYPE_IBF | KCS_BMC_EVENT_TYPE_OBE), 0);
 
 	return 0;
 }

drivers/char/ipmi/kcs_bmc_serio.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright (c) 2021 IBM Corp. */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/sched/signal.h>
+#include <linux/serio.h>
+#include <linux/slab.h>
+
+#include "kcs_bmc_client.h"
+
+struct kcs_bmc_serio {
+	struct list_head entry;
+
+	struct kcs_bmc_client client;
+	struct serio *port;
+
+	spinlock_t lock;
+};
+
+static inline struct kcs_bmc_serio *client_to_kcs_bmc_serio(struct kcs_bmc_client *client)
+{
+	return container_of(client, struct kcs_bmc_serio, client);
+}
+
+static irqreturn_t kcs_bmc_serio_event(struct kcs_bmc_client *client)
+{
+	struct kcs_bmc_serio *priv;
+	u8 handled = IRQ_NONE;
+	u8 status;
+
+	priv = client_to_kcs_bmc_serio(client);
+
+	spin_lock(&priv->lock);
+
+	status = kcs_bmc_read_status(client->dev);
+
+	if (status & KCS_BMC_STR_IBF)
+		handled = serio_interrupt(priv->port, kcs_bmc_read_data(client->dev), 0);
+
+	spin_unlock(&priv->lock);
+
+	return handled;
+}
+
+static const struct kcs_bmc_client_ops kcs_bmc_serio_client_ops = {
+	.event = kcs_bmc_serio_event,
+};
+
+static int kcs_bmc_serio_open(struct serio *port)
+{
+	struct kcs_bmc_serio *priv = port->port_data;
+
+	return kcs_bmc_enable_device(priv->client.dev, &priv->client);
+}
+
+static void kcs_bmc_serio_close(struct serio *port)
+{
+	struct kcs_bmc_serio *priv = port->port_data;
+
+	kcs_bmc_disable_device(priv->client.dev, &priv->client);
+}
+
+static DEFINE_SPINLOCK(kcs_bmc_serio_instances_lock);
+static LIST_HEAD(kcs_bmc_serio_instances);
+
+static int kcs_bmc_serio_add_device(struct kcs_bmc_device *kcs_bmc)
+{
+	struct kcs_bmc_serio *priv;
+	struct serio *port;
+
+	priv = devm_kzalloc(kcs_bmc->dev, sizeof(*priv), GFP_KERNEL);
+
+	/* Use kzalloc() as the allocation is cleaned up with kfree() via serio_unregister_port() */
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (!(priv && port))
+		return -ENOMEM;
+
+	port->id.type = SERIO_8042;
+	port->open = kcs_bmc_serio_open;
+	port->close = kcs_bmc_serio_close;
+	port->port_data = priv;
+	port->dev.parent = kcs_bmc->dev;
+
+	spin_lock_init(&priv->lock);
+	priv->port = port;
+	priv->client.dev = kcs_bmc;
+	priv->client.ops = &kcs_bmc_serio_client_ops;
+
+	spin_lock_irq(&kcs_bmc_serio_instances_lock);
+	list_add(&priv->entry, &kcs_bmc_serio_instances);
+	spin_unlock_irq(&kcs_bmc_serio_instances_lock);
+
+	serio_register_port(port);
+
+	dev_info(kcs_bmc->dev, "Initialised serio client for channel %d", kcs_bmc->channel);
+
+	return 0;
+}
+
+static int kcs_bmc_serio_remove_device(struct kcs_bmc_device *kcs_bmc)
+{
+	struct kcs_bmc_serio *priv = NULL, *pos;
+
+	spin_lock_irq(&kcs_bmc_serio_instances_lock);
+	list_for_each_entry(pos, &kcs_bmc_serio_instances, entry) {
+		if (pos->client.dev == kcs_bmc) {
+			priv = pos;
+			list_del(&pos->entry);
+			break;
+		}
+	}
+	spin_unlock_irq(&kcs_bmc_serio_instances_lock);
+
+	if (!priv)
+		return -ENODEV;
+
+	/* kfree()s priv->port via put_device() */
+	serio_unregister_port(priv->port);
+
+	/* Ensure the IBF IRQ is disabled if we were the active client */
+	kcs_bmc_disable_device(kcs_bmc, &priv->client);
+
+	devm_kfree(priv->client.dev->dev, priv);
+
+	return 0;
+}
+
+static const struct kcs_bmc_driver_ops kcs_bmc_serio_driver_ops = {
+	.add_device = kcs_bmc_serio_add_device,
+	.remove_device = kcs_bmc_serio_remove_device,
+};
+
+static struct kcs_bmc_driver kcs_bmc_serio_driver = {
+	.ops = &kcs_bmc_serio_driver_ops,
+};
+
+static int kcs_bmc_serio_init(void)
+{
+	kcs_bmc_register_driver(&kcs_bmc_serio_driver);
+
+	return 0;
+}
+module_init(kcs_bmc_serio_init);
+
+static void kcs_bmc_serio_exit(void)
+{
+	kcs_bmc_unregister_driver(&kcs_bmc_serio_driver);
+}
+module_exit(kcs_bmc_serio_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Andrew Jeffery <andrew@aj.id.au>");
+MODULE_DESCRIPTION("Adapter driver for serio access to BMC KCS devices");