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Date:   Thu, 14 Dec 2017 20:31:15 -0600
From:   Corey Minyard <minyard@....org>
To:     Haiyue Wang <haiyue.wang@...ux.intel.com>,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org,
        Cédric Le Goater <clg@...d.org>,
        Jeremy Kerr <jk@...abs.org>, Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>
Subject: Re: [PATCH linux ipmi for BMC] ipmi: add an Aspeed KCS IPMI BMC
 driver

On 12/14/2017 08:03 PM, Haiyue Wang wrote:
> [based torvalds/linux.git]
>
> 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.

Did you run this through checkpatch?  I saw a few things.

I was hoping to see some of the openbmc people comment on this.

-corey

> 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..bcbd2d6
> --- /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, "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, 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->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 */


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