[linux,dev-4.10] ipmi: add an Aspeed KCS IPMI BMC driver

Message ID 1512629633-22332-1-git-send-email-haiyue.wang@linux.intel.com
State Changes Requested, archived
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  • [linux,dev-4.10] ipmi: add an Aspeed KCS IPMI BMC driver
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Commit Message

Haiyue Wang Dec. 7, 2017, 6:53 a.m.
This patch adds a simple device driver to expose the KCS interface on
Aspeed SOCs (AST2500) as a character device. Such SOCs are commonly
used as BMC and this driver implements the BMC side of KCS interface.

Change-Id: Iee4003dc817bbf50568e1cf0d254e648d112545d
Signed-off-by: Haiyue Wang <haiyue.wang@linux.intel.com>
---
 .../devicetree/bindings/mfd/aspeed-lpc.txt         |  33 +-
 arch/arm/boot/dts/aspeed-g5.dtsi                   |  44 +-
 drivers/char/ipmi/Kconfig                          |  10 +
 drivers/char/ipmi/Makefile                         |   1 +
 drivers/char/ipmi/kcs-bmc.c                        | 833 +++++++++++++++++++++
 include/uapi/linux/kcs-bmc.h                       |  19 +
 6 files changed, 936 insertions(+), 4 deletions(-)
 create mode 100644 drivers/char/ipmi/kcs-bmc.c
 create mode 100644 include/uapi/linux/kcs-bmc.h

Patch

diff --git a/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt b/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt
index a97131a..1e9d119 100644
--- a/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt
+++ b/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt
@@ -62,12 +62,25 @@  BMC Node
 --------
 
 - compatible:	One of:
-		"aspeed,ast2400-lpc-bmc"
-		"aspeed,ast2500-lpc-bmc"
+		"aspeed,ast2400-lpc-bmc", "simple-mfd", "syscon"
+		"aspeed,ast2500-lpc-bmc", "simple-mfd", "syscon"
 
 - reg:		contains the physical address and length values of the
                 H8S/2168-compatible LPC controller memory region
 
+BMC KCS Node
+------------
+
+- compatible:	One of:
+		"aspeed,ast2500-kcs-bmc"
+
+- kcs_chan: The LPC channel number
+
+- kcs_regs: The KCS IDR,ODR,STR registers
+
+- kcs_addr: The host CPU IO map address
+
+
 Host Node
 ---------
 
@@ -94,8 +107,22 @@  lpc: lpc@1e789000 {
 	ranges = <0x0 0x1e789000 0x1000>;
 
 	lpc_bmc: lpc-bmc@0 {
-		compatible = "aspeed,ast2500-lpc-bmc";
+		compatible = "aspeed,ast2500-lpc-bmc"; "simple-mfd", "syscon";
 		reg = <0x0 0x80>;
+		reg-io-width = <4>;
+
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0x0 0x0 0x80>;
+
+		kcs3: kcs@3 {
+			compatible = "aspeed,ast2500-kcs-bmc";
+			interrupts = <8>;
+			kcs_chan = <3>;
+			kcs_regs = <0x2C 0x38 0x44>;
+			kcs_addr = <0xCA2>;
+			status = "okay";
+		};
 	};
 
 	lpc_host: lpc-host@80 {
diff --git a/arch/arm/boot/dts/aspeed-g5.dtsi b/arch/arm/boot/dts/aspeed-g5.dtsi
index ba3607c..90f260d 100644
--- a/arch/arm/boot/dts/aspeed-g5.dtsi
+++ b/arch/arm/boot/dts/aspeed-g5.dtsi
@@ -135,8 +135,40 @@ 
 			ranges = <0x0 0x1e789000 0x1000>;
 
 			lpc_bmc: lpc-bmc@0 {
-				compatible = "aspeed,ast2500-lpc-bmc";
+				compatible = "aspeed,ast2500-lpc-bmc", "simple-mfd", "syscon";
 				reg = <0x0 0x80>;
+				reg-io-width = <4>;
+
+				#address-cells = <1>;
+				#size-cells = <1>;
+				ranges = <0x0 0x0 0x80>;
+
+				kcs1: kcs@1 {
+					compatible = "aspeed,ast2500-kcs-bmc";
+					interrupts = <8>;
+					kcs_chan = <1>;
+					kcs_regs = <0x24 0x30 0x3C>;
+					kcs_addr = <0x0>;
+					status = "disabled";
+				};
+
+				kcs2: kcs@2 {
+					compatible = "aspeed,ast2500-kcs-bmc";
+					interrupts = <8>;
+					kcs_chan = <2>;
+					kcs_regs = <0x28 0x34 0x40>;
+					kcs_addr = <0x0>;
+					status = "disabled";
+				};
+
+				kcs3: kcs@3 {
+					compatible = "aspeed,ast2500-kcs-bmc";
+					interrupts = <8>;
+					kcs_chan = <3>;
+					kcs_regs = <0x2C 0x38 0x44>;
+					kcs_addr = <0x0>;
+					status = "disabled";
+				};
 			};
 
 			lpc_host: lpc-host@80 {
@@ -166,6 +198,16 @@ 
 					reg = <0x20 0x24 0x48 0x8>;
 				};
 
+				kcs4: kcs4@80 {
+					compatible = "aspeed,ast2500-kcs-bmc";
+					reg = <0x80 0x20>;
+					interrupts = <8>;
+					kcs_chan = <4>;
+					kcs_regs = <0x14 0x18 0x1C>;
+					kcs_addr = <0x0>;
+					status = "disabled";
+				};
+
 				mbox: mbox@180 {
 					compatible = "aspeed,ast2500-mbox";
 					reg = <0x180 0x5c>;
diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 90f3edf..9f8589f 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -85,3 +85,13 @@  config ASPEED_BT_IPMI_BMC
 	  Provides a driver for the BT (Block Transfer) IPMI interface
 	  found on Aspeed SOCs (AST2400 and AST2500). The driver
 	  implements the BMC side of the BT interface.
+
+config ASPEED_KCS_IPMI_BMC
+	depends on ARCH_ASPEED || COMPILE_TEST
+        depends on REGMAP && REGMAP_MMIO && MFD_SYSCON
+	tristate "KCS IPMI bmc driver"
+	default n
+	help
+	  Provides a driver for the KCS (Keyboard Controller Style) IPMI
+	  interface found on Aspeed SOCs (AST2500). The driver implements
+	  the BMC side of the KCS interface.
\ No newline at end of file
diff --git a/drivers/char/ipmi/Makefile b/drivers/char/ipmi/Makefile
index 0d98cd9..35272a7 100644
--- a/drivers/char/ipmi/Makefile
+++ b/drivers/char/ipmi/Makefile
@@ -12,3 +12,4 @@  obj-$(CONFIG_IPMI_POWERNV) += ipmi_powernv.o
 obj-$(CONFIG_IPMI_WATCHDOG) += ipmi_watchdog.o
 obj-$(CONFIG_IPMI_POWEROFF) += ipmi_poweroff.o
 obj-$(CONFIG_ASPEED_BT_IPMI_BMC) += bt-bmc.o
+obj-$(CONFIG_ASPEED_KCS_IPMI_BMC) += kcs-bmc.o
\ No newline at end of file
diff --git a/drivers/char/ipmi/kcs-bmc.c b/drivers/char/ipmi/kcs-bmc.c
new file mode 100644
index 0000000..aa4b910
--- /dev/null
+++ b/drivers/char/ipmi/kcs-bmc.c
@@ -0,0 +1,833 @@ 
+/*
+ * Copyright (c) 2015-2017, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/atomic.h>
+#include <linux/slab.h>
+#include <linux/kcs-bmc.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/poll.h>
+#include <linux/regmap.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+
+/*
+ * This is a BMC device used to communicate to the host
+ */
+#define DEVICE_NAME     "ipmi-kcs-host"
+
+
+/* Different Phases of the KCS Module */
+#define KCS_PHASE_IDLE          0x00
+#define KCS_PHASE_WRITE         0x01
+#define KCS_PHASE_WRITE_END     0x02
+#define KCS_PHASE_READ          0x03
+#define KCS_PHASE_ABORT         0x04
+#define KCS_PHASE_ERROR         0x05
+
+/* Abort Phase */
+#define ABORT_PHASE_ERROR1      0x01
+#define ABORT_PHASE_ERROR2      0x02
+
+/* KCS Command Control codes. */
+#define KCS_GET_STATUS          0x60
+#define KCS_ABORT               0x60
+#define KCS_WRITE_START         0x61
+#define KCS_WRITE_END           0x62
+#define KCS_READ_BYTE           0x68
+
+/* Status bits.:
+ * - IDLE_STATE.  Interface is idle. System software should not be expecting
+ *                nor sending any data.
+ * - READ_STATE.  BMC is transferring a packet to system software. System
+ *                software should be in the "Read Message" state.
+ * - WRITE_STATE. BMC is receiving a packet from system software. System
+ *                software should be writing a command to the BMC.
+ * - ERROR_STATE. BMC has detected a protocol violation at the interface level,
+ *                or the transfer has been aborted. System software can either
+ *                use the "Get_Status" control code to request the nature of
+ *                the error, or it can just retry the command.
+ */
+#define KCS_IDLE_STATE           0
+#define KCS_READ_STATE           1
+#define KCS_WRITE_STATE          2
+#define KCS_ERROR_STATE          3
+
+/* KCS Error Codes */
+#define KCS_NO_ERROR                0x00
+#define KCS_ABORTED_BY_COMMAND      0x01
+#define KCS_ILLEGAL_CONTROL_CODE    0x02
+#define KCS_LENGTH_ERROR            0x06
+#define KCS_UNSPECIFIED_ERROR       0xFF
+
+
+#define KCS_ZERO_DATA           0
+
+/* IPMI 2.0 - Table 9-1, KCS Interface Status Register Bits */
+#define KCS_STR_STATE(state)        (state << 6)
+#define KCS_STR_STATE_MASK          KCS_STR_STATE(0x3)
+#define KCS_STR_CMD_DAT             (1 << 3)
+#define KCS_STR_ATN                 (1 << 2)
+#define KCS_STR_IBF                 (1 << 1)
+#define KCS_STR_OBF                 (1)
+
+
+/***************************** LPC Register ****************************/
+#define LPC_HICR0            0x000
+#define     LPC_HICR0_LPC3E          (1 << 7)
+#define     LPC_HICR0_LPC2E          (1 << 6)
+#define     LPC_HICR0_LPC1E          (1 << 5)
+#define LPC_HICR2            0x008
+#define     LPC_HICR2_IBFIF3         (1 << 3)
+#define     LPC_HICR2_IBFIF2         (1 << 2)
+#define     LPC_HICR2_IBFIF1         (1 << 1)
+#define LPC_HICR4            0x010
+#define     LPC_HICR4_LADR12AS       (1 << 7)
+#define     LPC_HICR4_KCSENBL        (1 << 2)
+#define LPC_LADR3H           0x014
+#define LPC_LADR3L           0x018
+#define LPC_LADR12H          0x01C
+#define LPC_LADR12L          0x020
+
+#define LPC_HICRB            0x000
+#define     LPC_HICRB_IBFIF4         (1 << 1)
+#define     LPC_HICRB_LPC4E          (1 << 0)
+#define LPC_LADR4            0x010
+
+
+#define KCS_MSG_BUFSIZ      1024
+#define KCS_CHANNEL_MAX     4
+
+struct kcs_bmc {
+	struct regmap *map;
+	int            offset;
+	int            irq;
+	spinlock_t     lock;
+
+	u32 chan;
+	int running;
+
+	u32  idr; /* Input Data Register */
+	u32  odr; /* Output Data Register */
+	u32  str; /* Status Register */
+
+	int  kcs_phase;
+	u8   abort_phase;
+	u8   kcs_error;
+
+	wait_queue_head_t queue;
+	int  data_in_avail;
+	int  data_in_idx;
+	u8  *data_in;
+
+	int  data_out_idx;
+	int  data_out_len;
+	u8  *data_out;
+
+	struct miscdevice miscdev;
+	char name[16];
+};
+
+static u8 kcs_inb(struct kcs_bmc *kcs_bmc, u32 reg)
+{
+	u32 val = 0;
+	int rc;
+
+	rc = regmap_read(kcs_bmc->map, kcs_bmc->offset + reg, &val);
+	WARN(rc != 0, "kcs_inb failed: %d\n", rc);
+
+	return rc == 0 ? (u8) val : 0;
+}
+
+static void kcs_outb(struct kcs_bmc *kcs_bmc, u8 data, u32 reg)
+{
+	int rc;
+
+	rc = regmap_write(kcs_bmc->map, kcs_bmc->offset + reg, data);
+	WARN(rc != 0, "kcs_outb failed: %d\n", rc);
+}
+
+static void kcs_set_state(struct kcs_bmc *kcs_bmc, u8 state)
+{
+	int rc;
+
+	rc = regmap_update_bits(kcs_bmc->map, kcs_bmc->offset + kcs_bmc->str,
+				KCS_STR_STATE_MASK,
+				KCS_STR_STATE(state));
+	WARN(rc != 0, "KCS_STR_STATE failed: %d\n", rc);
+}
+
+static void kcs_set_atn(struct kcs_bmc *kcs_bmc, unsigned long set)
+{
+	int rc;
+
+	rc = regmap_update_bits(kcs_bmc->map, kcs_bmc->offset + kcs_bmc->str,
+				KCS_STR_ATN,
+				set != 0 ? KCS_STR_ATN : 0);
+	WARN(rc != 0, "KCS_STR_ATN failed: %d\n", rc);
+}
+
+/*********************************************************************
+ * AST_usrGuide_KCS.pdf
+ * 2. Background:
+ *   we note D for Data, and C for Cmd/Status, default rules are
+ *     A. KCS1 / KCS2 ( D / C:X / X+4 )
+ *        D / C : CA0h / CA4h
+ *        D / C : CA8h / CACh
+ *     B. KCS3 ( D / C:XX2h / XX3h )
+ *        D / C : CA2h / CA3h
+ *        D / C : CB2h / CB3h
+ *     C. KCS4
+ *        D / C : CA4h / CA5h
+ *********************************************************************/
+void kcs_set_addr(struct kcs_bmc *kcs_bmc, u16 addr)
+{
+	switch (kcs_bmc->chan) {
+	case 1:
+		regmap_update_bits(kcs_bmc->map, kcs_bmc->offset + LPC_HICR4,
+				LPC_HICR4_LADR12AS,
+				0);
+		regmap_write(kcs_bmc->map, kcs_bmc->offset + LPC_LADR12H,
+				addr >> 8);
+		regmap_write(kcs_bmc->map, kcs_bmc->offset + LPC_LADR12L,
+				addr & 0xFF);
+		break;
+
+	case 2:
+		regmap_update_bits(kcs_bmc->map, kcs_bmc->offset + LPC_HICR4,
+				LPC_HICR4_LADR12AS,
+				LPC_HICR4_LADR12AS);
+		regmap_write(kcs_bmc->map, kcs_bmc->offset + LPC_LADR12H,
+				addr >> 8);
+		regmap_write(kcs_bmc->map, kcs_bmc->offset + LPC_LADR12L,
+				addr & 0xFF);
+		break;
+
+	case 3:
+		regmap_write(kcs_bmc->map, kcs_bmc->offset + LPC_LADR3H,
+				addr >> 8);
+		regmap_write(kcs_bmc->map, kcs_bmc->offset + LPC_LADR3L,
+				addr & 0xFF);
+		break;
+
+	case 4:
+		regmap_write(kcs_bmc->map, kcs_bmc->offset + LPC_LADR4,
+				((addr + 1) << 16) | (addr));
+		break;
+
+	default:
+		break;
+	}
+}
+
+static void kcs_enable_channel(struct kcs_bmc *kcs_bmc, int enable)
+{
+	switch (kcs_bmc->chan) {
+	case 1:
+		if (enable) {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR2,
+					LPC_HICR2_IBFIF1, LPC_HICR2_IBFIF1);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR0,
+					LPC_HICR0_LPC1E, LPC_HICR0_LPC1E);
+		} else {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR0,
+					LPC_HICR0_LPC1E, 0);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR2,
+					LPC_HICR2_IBFIF1, 0);
+		}
+		break;
+
+	case 2:
+		if (enable) {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR2,
+					LPC_HICR2_IBFIF2, LPC_HICR2_IBFIF2);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR0,
+					LPC_HICR0_LPC2E, LPC_HICR0_LPC2E);
+		} else {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR0,
+					LPC_HICR0_LPC2E, 0);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR2,
+					LPC_HICR2_IBFIF2, 0);
+		}
+		break;
+
+	case 3:
+		if (enable) {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR2,
+					LPC_HICR2_IBFIF3, LPC_HICR2_IBFIF3);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR0,
+					LPC_HICR0_LPC3E, LPC_HICR0_LPC3E);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR4,
+					LPC_HICR4_KCSENBL, LPC_HICR4_KCSENBL);
+		} else {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR0,
+					LPC_HICR0_LPC3E, 0);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR4,
+					LPC_HICR4_KCSENBL, 0);
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICR2,
+					LPC_HICR2_IBFIF3, 0);
+		}
+		break;
+
+	case 4:
+		if (enable) {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICRB,
+					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E,
+					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E);
+		} else {
+			regmap_update_bits(kcs_bmc->map,
+					kcs_bmc->offset + LPC_HICRB,
+					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E,
+					0);
+		}
+		break;
+
+	default:
+		break;
+	}
+}
+
+static void kcs_rx_data(struct kcs_bmc *kcs_bmc)
+{
+	u8 data;
+
+	switch (kcs_bmc->kcs_phase) {
+	case KCS_PHASE_WRITE:
+		kcs_set_state(kcs_bmc, KCS_WRITE_STATE);
+
+		/* set OBF before reading data */
+		kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+
+		if (kcs_bmc->data_in_idx < KCS_MSG_BUFSIZ)
+			kcs_bmc->data_in[kcs_bmc->data_in_idx++] =
+					kcs_inb(kcs_bmc, kcs_bmc->idr);
+		break;
+
+	case KCS_PHASE_WRITE_END:
+		kcs_set_state(kcs_bmc, KCS_READ_STATE);
+
+		if (kcs_bmc->data_in_idx < KCS_MSG_BUFSIZ)
+			kcs_bmc->data_in[kcs_bmc->data_in_idx++] =
+					kcs_inb(kcs_bmc, kcs_bmc->idr);
+
+		kcs_bmc->kcs_phase = KCS_PHASE_READ;
+		if (kcs_bmc->running) {
+			kcs_bmc->data_in_avail = 1;
+			wake_up_interruptible(&kcs_bmc->queue);
+		}
+		break;
+
+	case KCS_PHASE_READ:
+		if (kcs_bmc->data_out_idx == kcs_bmc->data_out_len)
+			kcs_set_state(kcs_bmc, KCS_IDLE_STATE);
+
+		data = kcs_inb(kcs_bmc, kcs_bmc->idr);
+		if (data != KCS_READ_BYTE) {
+			kcs_set_state(kcs_bmc, KCS_ERROR_STATE);
+			kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+			break;
+		}
+
+		if (kcs_bmc->data_out_idx == kcs_bmc->data_out_len) {
+			kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+			kcs_bmc->kcs_phase = KCS_PHASE_IDLE;
+			break;
+		}
+
+		kcs_outb(kcs_bmc, kcs_bmc->data_out[kcs_bmc->data_out_idx++],
+				 kcs_bmc->odr);
+		break;
+
+	case KCS_PHASE_ABORT:
+		switch (kcs_bmc->abort_phase) {
+		case ABORT_PHASE_ERROR1:
+			kcs_set_state(kcs_bmc, KCS_READ_STATE);
+
+			/* Read the Dummy byte */
+			kcs_inb(kcs_bmc, kcs_bmc->idr);
+
+			kcs_outb(kcs_bmc, kcs_bmc->kcs_error, kcs_bmc->odr);
+			kcs_bmc->abort_phase = ABORT_PHASE_ERROR2;
+			break;
+
+		case ABORT_PHASE_ERROR2:
+			kcs_set_state(kcs_bmc, KCS_IDLE_STATE);
+
+			/* Read the Dummy byte */
+			kcs_inb(kcs_bmc, kcs_bmc->idr);
+
+			kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+			kcs_bmc->kcs_phase = KCS_PHASE_IDLE;
+			kcs_bmc->abort_phase = 0;
+			break;
+
+		default:
+			break;
+		}
+
+		break;
+
+	case KCS_PHASE_ERROR:
+		kcs_set_state(kcs_bmc, KCS_ERROR_STATE);
+
+		/* Read the Dummy byte */
+		kcs_inb(kcs_bmc, kcs_bmc->idr);
+
+		kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+		break;
+
+	default:
+		kcs_set_state(kcs_bmc, KCS_ERROR_STATE);
+
+		/* Read the Dummy byte */
+		kcs_inb(kcs_bmc, kcs_bmc->idr);
+
+		kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+		break;
+	}
+}
+
+static void kcs_rx_cmd(struct kcs_bmc *kcs_bmc)
+{
+	u8 cmd;
+
+	kcs_set_state(kcs_bmc, KCS_WRITE_STATE);
+
+	/* Dummy data to generate OBF */
+	kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+
+	cmd = kcs_inb(kcs_bmc, kcs_bmc->idr);
+	switch (cmd) {
+	case KCS_WRITE_START:
+		kcs_bmc->data_in_avail = 0;
+		kcs_bmc->data_in_idx   = 0;
+		kcs_bmc->kcs_phase     = KCS_PHASE_WRITE;
+		kcs_bmc->kcs_error     = KCS_NO_ERROR;
+		break;
+
+	case KCS_WRITE_END:
+		kcs_bmc->kcs_phase = KCS_PHASE_WRITE_END;
+		break;
+
+	case KCS_ABORT:
+		if (kcs_bmc->kcs_error == KCS_NO_ERROR)
+			kcs_bmc->kcs_error = KCS_ABORTED_BY_COMMAND;
+
+		kcs_bmc->kcs_phase   = KCS_PHASE_ABORT;
+		kcs_bmc->abort_phase = ABORT_PHASE_ERROR1;
+		break;
+
+	default:
+		kcs_bmc->kcs_error = KCS_ILLEGAL_CONTROL_CODE;
+		kcs_set_state(kcs_bmc, KCS_ERROR_STATE);
+		kcs_outb(kcs_bmc, kcs_bmc->kcs_error, kcs_bmc->odr);
+		kcs_bmc->kcs_phase = KCS_PHASE_ERROR;
+		break;
+	}
+}
+
+/*
+ * Whenever the BMC is reset (from power-on or a hard reset), the State Bits
+ * are initialized to "11 - Error State". Doing so allows SMS to detect that
+ * the BMC has been reset and that any message in process has been terminated
+ * by the BMC.
+ */
+static void kcs_force_abort(struct kcs_bmc *kcs_bmc)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&kcs_bmc->lock, flags);
+	kcs_set_state(kcs_bmc, KCS_ERROR_STATE);
+
+	/* Read the Dummy byte */
+	kcs_inb(kcs_bmc, kcs_bmc->idr);
+
+	kcs_outb(kcs_bmc, KCS_ZERO_DATA, kcs_bmc->odr);
+	kcs_bmc->kcs_phase = KCS_PHASE_ERROR;
+	spin_unlock_irqrestore(&kcs_bmc->lock, flags);
+}
+
+static irqreturn_t kcs_bmc_irq(int irq, void *arg)
+{
+	int rc;
+	u32 sts;
+	struct kcs_bmc *kcs_bmc = arg;
+
+	rc = regmap_read(kcs_bmc->map, kcs_bmc->offset + kcs_bmc->str, &sts);
+	if (rc)
+		return IRQ_NONE;
+
+	sts &= (KCS_STR_IBF | KCS_STR_CMD_DAT);
+
+	switch (sts) {
+	case KCS_STR_IBF | KCS_STR_CMD_DAT:
+		kcs_rx_cmd(kcs_bmc);
+		break;
+
+	case KCS_STR_IBF:
+		kcs_rx_data(kcs_bmc);
+
+	default:
+		return IRQ_NONE;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int kcs_bmc_config_irq(struct kcs_bmc *kcs_bmc,
+			struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	int rc;
+
+	kcs_bmc->irq = platform_get_irq(pdev, 0);
+	if (!kcs_bmc->irq)
+		return -ENODEV;
+
+	rc = devm_request_irq(dev, kcs_bmc->irq, kcs_bmc_irq, IRQF_SHARED,
+			kcs_bmc->name, kcs_bmc);
+	if (rc < 0) {
+		dev_warn(dev, "Unable to request IRQ %d\n", kcs_bmc->irq);
+		kcs_bmc->irq = 0;
+		return rc;
+	}
+
+	return rc;
+}
+
+
+static inline struct kcs_bmc *file_kcs_bmc(struct file *filp)
+{
+	return container_of(filp->private_data, struct kcs_bmc, miscdev);
+}
+
+static int kcs_bmc_open(struct inode *inode, struct file *filp)
+{
+	unsigned long flags;
+	struct kcs_bmc *kcs_bmc = file_kcs_bmc(filp);
+
+	if (kcs_bmc->running)
+		return -EBUSY;
+
+	spin_lock_irqsave(&kcs_bmc->lock, flags);
+	kcs_bmc->kcs_phase     = KCS_PHASE_IDLE;
+	kcs_bmc->running       = 1;
+	kcs_bmc->data_in_avail = 0;
+	spin_unlock_irqrestore(&kcs_bmc->lock, flags);
+
+	return 0;
+}
+
+static unsigned int kcs_bmc_poll(struct file *filp, poll_table *wait)
+{
+	unsigned int mask = 0;
+	struct kcs_bmc *kcs_bmc = file_kcs_bmc(filp);
+
+	poll_wait(filp, &kcs_bmc->queue, wait);
+
+	if (kcs_bmc->data_in_avail)
+		mask |= POLLIN;
+
+	if (kcs_bmc->kcs_phase == KCS_PHASE_READ)
+		mask |= POLLOUT;
+
+	return mask;
+}
+
+static ssize_t kcs_bmc_read(struct file *filp, char *buf,
+			    size_t count, loff_t *offset)
+{
+	int rv;
+	struct kcs_bmc *kcs_bmc = file_kcs_bmc(filp);
+
+	rv = wait_event_interruptible(kcs_bmc->queue,
+				kcs_bmc->data_in_avail != 0);
+	if (rv < 0)
+		return -ERESTARTSYS;
+
+	kcs_bmc->data_in_avail = 0;
+
+	if (count > kcs_bmc->data_in_idx)
+		count = kcs_bmc->data_in_idx;
+
+	if (copy_to_user(buf, kcs_bmc->data_in, count))
+		return -EFAULT;
+
+	return count;
+}
+
+static ssize_t kcs_bmc_write(struct file *filp, const char *buf,
+			     size_t count, loff_t *offset)
+{
+	unsigned long flags;
+	struct kcs_bmc *kcs_bmc = file_kcs_bmc(filp);
+
+	if (count < 1 || count > KCS_MSG_BUFSIZ)
+		return -EINVAL;
+
+	if (copy_from_user(kcs_bmc->data_out, buf, count))
+		return -EFAULT;
+
+	spin_lock_irqsave(&kcs_bmc->lock, flags);
+	if (kcs_bmc->kcs_phase == KCS_PHASE_READ) {
+		kcs_bmc->data_out_idx = 1;
+		kcs_bmc->data_out_len = count;
+		kcs_outb(kcs_bmc, kcs_bmc->data_out[0], kcs_bmc->odr);
+	}
+	spin_unlock_irqrestore(&kcs_bmc->lock, flags);
+
+	return count;
+}
+
+static long kcs_bmc_ioctl(struct file *filp, unsigned int cmd,
+			  unsigned long arg)
+{
+	long ret = 0;
+	struct kcs_bmc *kcs_bmc = file_kcs_bmc(filp);
+
+	switch (cmd) {
+	case KCS_BMC_IOCTL_SMS_ATN:
+		kcs_set_atn(kcs_bmc, arg);
+		break;
+
+	case KCS_BMC_IOCTL_FORCE_ABORT:
+		kcs_force_abort(kcs_bmc);
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static int kcs_bmc_release(struct inode *inode, struct file *filp)
+{
+	unsigned long flags;
+	struct kcs_bmc *kcs_bmc = file_kcs_bmc(filp);
+
+	spin_lock_irqsave(&kcs_bmc->lock, flags);
+	kcs_bmc->running = 0;
+	spin_unlock_irqrestore(&kcs_bmc->lock, flags);
+
+	return 0;
+}
+
+static const struct file_operations kcs_bmc_fops = {
+	.owner          = THIS_MODULE,
+	.open           = kcs_bmc_open,
+	.read           = kcs_bmc_read,
+	.write          = kcs_bmc_write,
+	.release        = kcs_bmc_release,
+	.poll           = kcs_bmc_poll,
+	.unlocked_ioctl = kcs_bmc_ioctl,
+};
+
+static const struct regmap_config kcs_regmap_cfg = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+};
+
+static int kcs_bmc_probe(struct platform_device *pdev)
+{
+	struct kcs_bmc *kcs_bmc;
+	struct device *dev;
+	u32 chan, addr, io_regs[3];
+	int rc;
+
+	if (!pdev || !pdev->dev.of_node)
+		return -ENODEV;
+
+	dev = &pdev->dev;
+
+	rc = of_property_read_u32(dev->of_node, "kcs_chan", &chan);
+	if (rc) {
+		dev_err(dev, "no 'kcs_chan' configured\n");
+		return -ENODEV;
+	}
+
+	if (chan == 0 || chan > KCS_CHANNEL_MAX) {
+		dev_err(dev, "invalid 'kcs_chan' = '%u' is configured\n", chan);
+		return -ENODEV;
+	}
+
+	rc = of_property_read_u32(dev->of_node, "kcs_addr", &addr);
+	if (rc) {
+		dev_err(dev, "no 'kcs_addr' configured\n");
+		return -ENODEV;
+	}
+
+	rc = of_property_read_u32_array(dev->of_node, "kcs_regs", io_regs,
+			ARRAY_SIZE(io_regs));
+	if (rc) {
+		dev_err(dev, "no 'kcs_regs' configured\n");
+		return -ENODEV;
+	}
+
+	kcs_bmc = devm_kzalloc(dev, sizeof(*kcs_bmc), GFP_KERNEL);
+	if (!kcs_bmc)
+		return -ENOMEM;
+
+	kcs_bmc->map = syscon_node_to_regmap(dev->parent->of_node);
+	if (IS_ERR(kcs_bmc->map)) {
+		struct resource *res;
+		void __iomem *base;
+
+		/*
+		 * Assume it's not the MFD-based devicetree description, in
+		 * which case generate a regmap ourselves
+		 */
+		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+		base = devm_ioremap_resource(&pdev->dev, res);
+		if (IS_ERR(base)) {
+			dev_err(dev, "ioremap error\n");
+			return PTR_ERR(base);
+		}
+
+		kcs_bmc->map = devm_regmap_init_mmio(dev, base,
+					&kcs_regmap_cfg);
+		if (IS_ERR(kcs_bmc->map)) {
+			dev_err(dev, "regmap init error\n");
+			return PTR_ERR(base);
+		}
+
+		kcs_bmc->offset = 0;
+	} else {
+		rc = of_property_read_u32(dev->of_node, "reg",
+					&kcs_bmc->offset);
+		if (rc) {
+			rc = of_property_read_u32(dev->parent->of_node, "reg",
+					&kcs_bmc->offset);
+			if (rc) {
+				dev_err(dev, "no 'reg' configured\n");
+				return rc;
+			}
+		}
+	}
+
+	spin_lock_init(&kcs_bmc->lock);
+	kcs_bmc->chan = chan;
+	kcs_bmc->idr  = io_regs[0];
+	kcs_bmc->odr  = io_regs[1];
+	kcs_bmc->str  = io_regs[2];
+
+	init_waitqueue_head(&kcs_bmc->queue);
+	kcs_bmc->data_in  = kmalloc(KCS_MSG_BUFSIZ, GFP_KERNEL);
+	kcs_bmc->data_out = kmalloc(KCS_MSG_BUFSIZ, GFP_KERNEL);
+	if (kcs_bmc->data_in == NULL || kcs_bmc->data_out == NULL) {
+		rc = -ENOMEM;
+		dev_err(dev, "KCS%u failed data_in=%p, data_out=%p\n",
+			     kcs_bmc->chan,
+			     kcs_bmc->data_in,
+			     kcs_bmc->data_out);
+		goto bail;
+	}
+
+	snprintf(kcs_bmc->name, sizeof(kcs_bmc->name), "ipmi-kcs%u", chan);
+	kcs_bmc->miscdev.minor = MISC_DYNAMIC_MINOR;
+	kcs_bmc->miscdev.name = kcs_bmc->name;
+	kcs_bmc->miscdev.fops = &kcs_bmc_fops;
+	rc = misc_register(&kcs_bmc->miscdev);
+	if (rc) {
+		dev_err(dev, "Unable to register misc device\n");
+		goto bail;
+	}
+
+	kcs_set_addr(kcs_bmc, addr);
+	kcs_enable_channel(kcs_bmc, 1);
+
+	kcs_bmc_config_irq(kcs_bmc, pdev);
+	if (kcs_bmc->irq)
+		dev_info(dev, "Using IRQ %d\n", kcs_bmc->irq);
+	else
+		dev_info(dev, "No IRQ\n");
+
+	dev_info(dev, "Found BMC KCS%u@0x%X :\n"
+		      " IDR=0x%X, ODR=0x%X, STR=0x%X Offset=0x%X\n",
+			kcs_bmc->chan, addr,
+			kcs_bmc->idr,
+			kcs_bmc->odr,
+			kcs_bmc->str,
+			kcs_bmc->offset);
+
+	dev_set_drvdata(&pdev->dev, kcs_bmc);
+
+	return 0;
+
+bail:
+	kfree(kcs_bmc->data_in);
+	kfree(kcs_bmc->data_out);
+	kcs_bmc->data_in = NULL;
+	kcs_bmc->data_out = NULL;
+	return rc;
+}
+
+static int kcs_bmc_remove(struct platform_device *pdev)
+{
+	struct kcs_bmc *kcs_bmc = dev_get_drvdata(&pdev->dev);
+
+	if (kcs_bmc == NULL)
+		return 0;
+
+	platform_set_drvdata(pdev, NULL);
+
+	kfree(kcs_bmc->data_in);
+	kfree(kcs_bmc->data_out);
+	kcs_bmc->data_in = NULL;
+	kcs_bmc->data_out = NULL;
+
+	misc_deregister(&kcs_bmc->miscdev);
+
+	return 0;
+}
+
+static const struct of_device_id kcs_bmc_match[] = {
+	{ .compatible = "aspeed,ast2500-kcs-bmc" },
+	{ },
+};
+
+static struct platform_driver kcs_bmc_driver = {
+	.driver = {
+		.name           = DEVICE_NAME,
+		.of_match_table = kcs_bmc_match,
+	},
+	.probe = kcs_bmc_probe,
+	.remove = kcs_bmc_remove,
+};
+
+module_platform_driver(kcs_bmc_driver);
+
+MODULE_DEVICE_TABLE(of, kcs_bmc_match);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Haiyue Wang <haiyue.wang@linux.intel.com>");
+MODULE_DESCRIPTION("Linux device interface to the IPMI KCS interface");
+
diff --git a/include/uapi/linux/kcs-bmc.h b/include/uapi/linux/kcs-bmc.h
new file mode 100644
index 0000000..ffb77eb
--- /dev/null
+++ b/include/uapi/linux/kcs-bmc.h
@@ -0,0 +1,19 @@ 
+/*
+ * Copyright (c) 2015-2017, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#ifndef _UAPI_LINUX_KCS_BMC_H
+#define _UAPI_LINUX_KCS_BMC_H
+
+#include <linux/ioctl.h>
+
+#define __KCS_BMC_IOCTL_MAGIC      'K'
+#define KCS_BMC_IOCTL_SMS_ATN      _IOW(__KCS_BMC_IOCTL_MAGIC, 1, unsigned long)
+#define KCS_BMC_IOCTL_FORCE_ABORT  _IO(__KCS_BMC_IOCTL_MAGIC, 2)
+
+#endif /* _UAPI_LINUX_KCS_BMC_H */
+