Message-Id: <1513312484-4688-1-git-send-email-haiyue.wang@linux.intel.com>
Date:   Fri, 15 Dec 2017 12:34:44 +0800
From:   Haiyue Wang <haiyue.wang@...ux.intel.com>
To:     minyard@....org, openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, clg@...d.org, jk@...abs.org,
        joel@....id.au, andrew@...id.au
Cc:     Haiyue Wang <haiyue.wang@...ux.intel.com>
Subject: [PATCH linux ipmi for BMC v2] ipmi: add an Aspeed KCS IPMI BMC driver

This patch adds a simple device driver to expose the KCS interface on
Aspeed SOCs (AST2400 and AST2500) as a character device. Such SOCs are
commonly used as BMCs (BaseBoard Management Controllers) and this driver
implements the BMC side of the KCS interface.

The KCS (Keyboard Controller Style) interface is used to perform in-band
IPMI communication between a host and its BMC.

The device name defaults to '/dev/ipmi-kcsX', X=1,2,3,4.

Signed-off-by: Haiyue Wang <haiyue.wang@...ux.intel.com>
---
 .../devicetree/bindings/mfd/aspeed-lpc.txt         |  31 +-
 drivers/char/ipmi/Kconfig                          |   9 +
 drivers/char/ipmi/Makefile                         |   1 +
 drivers/char/ipmi/kcs-bmc.c                        | 759 +++++++++++++++++++++
 include/uapi/linux/kcs-bmc.h                       |  13 +
 5 files changed, 810 insertions(+), 3 deletions(-)
 create mode 100644 drivers/char/ipmi/kcs-bmc.c
 create mode 100644 include/uapi/linux/kcs-bmc.h

diff --git a/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt b/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt
index 514d82c..e682000 100644
--- a/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt
+++ b/Documentation/devicetree/bindings/mfd/aspeed-lpc.txt
@@ -62,12 +62,24 @@ 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,ast2400-kcs-bmc"
+		"aspeed,ast2500-kcs-bmc"
+
+- kcs_chan: The LPC channel number
+
+- kcs_addr: The host CPU IO map address
+
+
 Host Node
 ---------
 
@@ -94,8 +106,21 @@ lpc: lpc@...89000 {
 	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: kcs3@0 {
+			compatible = "aspeed,ast2500-kcs-bmc";
+			interrupts = <8>;
+			kcs_chan = <3>;
+			kcs_addr = <0xCA2>;
+			status = "okay";
+		};
 	};
 
 	lpc_host: lpc-host@80 {
diff --git a/drivers/char/ipmi/Kconfig b/drivers/char/ipmi/Kconfig
index 3544abc..3a9d29b 100644
--- a/drivers/char/ipmi/Kconfig
+++ b/drivers/char/ipmi/Kconfig
@@ -104,3 +104,12 @@ 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"
+	help
+	  Provides a driver for the KCS (Keyboard Controller Style) IPMI
+	  interface found on Aspeed SOCs (AST2400 and 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 33b899f..f217bae 100644
--- a/drivers/char/ipmi/Makefile
+++ b/drivers/char/ipmi/Makefile
@@ -22,3 +22,4 @@ 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..256fb00
--- /dev/null
+++ b/drivers/char/ipmi/kcs-bmc.c
@@ -0,0 +1,759 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2015-2017, Intel Corporation.
+
+#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>
+
+#define KCS_MSG_BUFSIZ      1024
+#define KCS_CHANNEL_MAX     4
+
+/*
+ * 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             BIT(3)
+#define KCS_STR_ATN                 BIT(2)
+#define KCS_STR_IBF                 BIT(1)
+#define KCS_STR_OBF                 BIT(0)
+
+
+/***************************** LPC Register ****************************/
+/* mapped to lpc-bmc@0 IO space */
+#define LPC_HICR0            0x000
+#define     LPC_HICR0_LPC3E          BIT(7)
+#define     LPC_HICR0_LPC2E          BIT(6)
+#define     LPC_HICR0_LPC1E          BIT(5)
+#define LPC_HICR2            0x008
+#define     LPC_HICR2_IBFIF3         BIT(3)
+#define     LPC_HICR2_IBFIF2         BIT(2)
+#define     LPC_HICR2_IBFIF1         BIT(1)
+#define LPC_HICR4            0x010
+#define     LPC_HICR4_LADR12AS       BIT(7)
+#define     LPC_HICR4_KCSENBL        BIT(2)
+#define LPC_LADR3H           0x014
+#define LPC_LADR3L           0x018
+#define LPC_LADR12H          0x01C
+#define LPC_LADR12L          0x020
+#define LPC_IDR1             0x024
+#define LPC_IDR2             0x028
+#define LPC_IDR3             0x02C
+#define LPC_ODR1             0x030
+#define LPC_ODR2             0x034
+#define LPC_ODR3             0x038
+#define LPC_STR1             0x03C
+#define LPC_STR2             0x040
+#define LPC_STR3             0x044
+
+/* mapped to lpc-host@80 IO space */
+#define LPC_HICRB            0x080
+#define     LPC_HICRB_IBFIF4         BIT(1)
+#define     LPC_HICRB_LPC4E          BIT(0)
+#define LPC_LADR4            0x090
+#define LPC_IDR4             0x094
+#define LPC_ODR4             0x098
+#define LPC_STR4             0x09C
+
+
+/* IPMI 2.0 - 9.5, KCS Interface Registers */
+struct kcs_ioreg {
+	u32 idr; /* Input Data Register */
+	u32 odr; /* Output Data Register */
+	u32 str; /* Status Register */
+};
+
+static const struct kcs_ioreg kcs_channel_ioregs[KCS_CHANNEL_MAX] = {
+	{ .idr = LPC_IDR1, .odr = LPC_ODR1, .str = LPC_STR1 },
+	{ .idr = LPC_IDR2, .odr = LPC_ODR2, .str = LPC_STR2 },
+	{ .idr = LPC_IDR3, .odr = LPC_ODR3, .str = LPC_STR3 },
+	{ .idr = LPC_IDR4, .odr = LPC_ODR4, .str = LPC_STR4 },
+};
+
+struct kcs_bmc {
+	struct regmap *map;
+	int            irq;
+	spinlock_t     lock;
+
+	u32 chan;
+	int running;
+
+	u32 idr;
+	u32 odr;
+	u32 str;
+
+	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, reg, &val);
+	WARN(rc != 0, "regmap_read 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, reg, data);
+	WARN(rc != 0, "regmap_write 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->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->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, LPC_HICR4,
+				LPC_HICR4_LADR12AS,
+				0);
+		regmap_write(kcs_bmc->map, LPC_LADR12H, addr >> 8);
+		regmap_write(kcs_bmc->map, LPC_LADR12L, addr & 0xFF);
+		break;
+
+	case 2:
+		regmap_update_bits(kcs_bmc->map, LPC_HICR4,
+				LPC_HICR4_LADR12AS,
+				LPC_HICR4_LADR12AS);
+		regmap_write(kcs_bmc->map, LPC_LADR12H, addr >> 8);
+		regmap_write(kcs_bmc->map, LPC_LADR12L, addr & 0xFF);
+		break;
+
+	case 3:
+		regmap_write(kcs_bmc->map, LPC_LADR3H, addr >> 8);
+		regmap_write(kcs_bmc->map, LPC_LADR3L, addr & 0xFF);
+		break;
+
+	case 4:
+		regmap_write(kcs_bmc->map, 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, LPC_HICR2,
+					LPC_HICR2_IBFIF1, LPC_HICR2_IBFIF1);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR0,
+					LPC_HICR0_LPC1E, LPC_HICR0_LPC1E);
+		} else {
+			regmap_update_bits(kcs_bmc->map, LPC_HICR0,
+					LPC_HICR0_LPC1E, 0);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR2,
+					LPC_HICR2_IBFIF1, 0);
+		}
+		break;
+
+	case 2:
+		if (enable) {
+			regmap_update_bits(kcs_bmc->map, LPC_HICR2,
+					LPC_HICR2_IBFIF2, LPC_HICR2_IBFIF2);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR0,
+					LPC_HICR0_LPC2E, LPC_HICR0_LPC2E);
+		} else {
+			regmap_update_bits(kcs_bmc->map, LPC_HICR0,
+					LPC_HICR0_LPC2E, 0);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR2,
+					LPC_HICR2_IBFIF2, 0);
+		}
+		break;
+
+	case 3:
+		if (enable) {
+			regmap_update_bits(kcs_bmc->map, LPC_HICR2,
+					LPC_HICR2_IBFIF3, LPC_HICR2_IBFIF3);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR0,
+					LPC_HICR0_LPC3E, LPC_HICR0_LPC3E);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR4,
+					LPC_HICR4_KCSENBL, LPC_HICR4_KCSENBL);
+		} else {
+			regmap_update_bits(kcs_bmc->map, LPC_HICR0,
+					LPC_HICR0_LPC3E, 0);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR4,
+					LPC_HICR4_KCSENBL, 0);
+			regmap_update_bits(kcs_bmc->map, LPC_HICR2,
+					LPC_HICR2_IBFIF3, 0);
+		}
+		break;
+
+	case 4:
+		if (enable) {
+			regmap_update_bits(kcs_bmc->map, LPC_HICRB,
+					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E,
+					LPC_HICRB_IBFIF4 | LPC_HICRB_LPC4E);
+		} else {
+			regmap_update_bits(kcs_bmc->map, 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->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 int kcs_bmc_probe(struct platform_device *pdev)
+{
+	struct kcs_bmc *kcs_bmc;
+	struct device *dev;
+	const struct kcs_ioreg *ioreg;
+	u32 chan, addr;
+	int rc;
+
+	dev = &pdev->dev;
+
+	kcs_bmc = devm_kzalloc(dev, sizeof(*kcs_bmc), GFP_KERNEL);
+	if (!kcs_bmc)
+		return -ENOMEM;
+
+	rc = of_property_read_u32(dev->of_node, "kcs_chan", &chan);
+	if ((rc != 0) || (chan == 0 || chan > KCS_CHANNEL_MAX)) {
+		dev_err(dev, "no valid 'kcs_chan' configured\n");
+		return -ENODEV;
+	}
+
+	rc = of_property_read_u32(dev->of_node, "kcs_addr", &addr);
+	if (rc) {
+		dev_err(dev, "no valid 'kcs_addr' configured\n");
+		return -ENODEV;
+	}
+
+	kcs_bmc->map = syscon_node_to_regmap(dev->parent->of_node);
+	if (IS_ERR(kcs_bmc->map)) {
+		dev_err(dev, "Couldn't get regmap\n");
+		return -ENODEV;
+	}
+
+	spin_lock_init(&kcs_bmc->lock);
+	kcs_bmc->chan = chan;
+
+	ioreg = &kcs_channel_ioregs[chan - 1];
+	kcs_bmc->idr  = ioreg->idr;
+	kcs_bmc->odr  = ioreg->odr;
+	kcs_bmc->str  = ioreg->str;
+
+	init_waitqueue_head(&kcs_bmc->queue);
+	kcs_bmc->data_in  = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+	kcs_bmc->data_out = devm_kmalloc(dev, KCS_MSG_BUFSIZ, GFP_KERNEL);
+	if (kcs_bmc->data_in == NULL || kcs_bmc->data_out == NULL) {
+		dev_err(dev, "Failed to allocate data buffers\n");
+		return -ENOMEM;
+	}
+
+	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 device\n");
+		return rc;
+	}
+
+	kcs_set_addr(kcs_bmc, addr);
+	kcs_enable_channel(kcs_bmc, 1);
+
+	rc = kcs_bmc_config_irq(kcs_bmc, pdev);
+	if (rc) {
+		dev_err(dev, "Failed to configure IRQ\n");
+		misc_deregister(&kcs_bmc->miscdev);
+		return rc;
+	}
+
+	dev_set_drvdata(&pdev->dev, kcs_bmc);
+
+	dev_info(dev, "addr=0x%x, idr=0x%x, odr=0x%x, str=0x%x\n",
+			addr,
+			kcs_bmc->idr, kcs_bmc->odr, kcs_bmc->str);
+
+	return 0;
+}
+
+static int kcs_bmc_remove(struct platform_device *pdev)
+{
+	struct kcs_bmc *kcs_bmc = dev_get_drvdata(&pdev->dev);
+
+	misc_deregister(&kcs_bmc->miscdev);
+
+	return 0;
+}
+
+static const struct of_device_id kcs_bmc_match[] = {
+	{ .compatible = "aspeed,ast2400-kcs-bmc" },
+	{ .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@...ux.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..f0c3ff60
--- /dev/null
+++ b/include/uapi/linux/kcs-bmc.h
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2015-2017, Intel Corporation.
+
+#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 */
-- 
2.7.4

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