Re: [PATCH v12 6/9] LPC: Support the LPC host on Hip06/Hip07 with DT bindings

[dann frazier]

On Wed, Jan 24, 2018 at 12:36:22AM +0800, John Garry wrote:
> From: Zhichang Yuan <yuanzhichang@xxxxxxxxxxxxx>
> 
> The low-pin-count(LPC) interface of Hip06/Hip07 accesses the peripherals in
> I/O port addresses. This patch implements the LPC host controller driver
> which perform the I/O operations on the underlying hardware.
> We don't want to touch those existing peripherals' driver, such as ipmi-bt.
> So this driver applies the indirect-IO introduced in the previous patch
> after registering an indirect-IO node to the indirect-IO devices list which
> will be searched in the I/O accessors to retrieve the host-local I/O port.
> 
> The driver config is set as a bool instead of a trisate. The reason
> here is that, by the very nature of the driver providing a logical
> PIO range, it does not make sense to have this driver as a loadable
> module. Another more specific reason is that the Huawei D03 board
> which includes hip06 SoC requires the LPC bus for UART console, so
> should be built in.
> 
> Signed-off-by: Zou Rongrong <zourongrong@xxxxxxxxxx>
> Signed-off-by: Zhichang Yuan <yuanzhichang@xxxxxxxxxxxxx>
> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@xxxxxxxxxx>
> Acked-by: Rob Herring <robh@xxxxxxxxxx> #dts part
> ---
>  .../arm/hisilicon/hisilicon-low-pin-count.txt      |  33 ++
>  drivers/bus/Kconfig                                |   8 +
>  drivers/bus/Makefile                               |   1 +
>  drivers/bus/hisi_lpc.c                             | 526 +++++++++++++++++++++
>  4 files changed, 568 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/hisilicon/hisilicon-low-pin-count.txt
>  create mode 100644 drivers/bus/hisi_lpc.c
> 
> diff --git a/Documentation/devicetree/bindings/arm/hisilicon/hisilicon-low-pin-count.txt b/Documentation/devicetree/bindings/arm/hisilicon/hisilicon-low-pin-count.txt
> new file mode 100644
> index 0000000..213181f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/hisilicon/hisilicon-low-pin-count.txt
> @@ -0,0 +1,33 @@
> +Hisilicon Hip06 low-pin-count device
> +  Hisilicon Hip06 SoCs implement a Low Pin Count (LPC) controller, which
> +  provides I/O access to some legacy ISA devices.
> +  Hip06 is based on arm64 architecture where there is no I/O space. So, the
> +  I/O ports here are not cpu addresses, and there is no 'ranges' property in
> +  LPC device node.
> +
> +Required properties:
> +- compatible:  value should be as follows:
> +	(a) "hisilicon,hip06-lpc"
> +	(b) "hisilicon,hip07-lpc"
> +- #address-cells: must be 2 which stick to the ISA/EISA binding doc.
> +- #size-cells: must be 1 which stick to the ISA/EISA binding doc.
> +- reg: base memory range where the LPC register set is mapped.
> +
> +Note:
> +  The node name before '@' must be "isa" to represent the binding stick to the
> +  ISA/EISA binding specification.
> +
> +Example:
> +
> +isa@a01b0000 {
> +	compatible = "hisilicon,hip06-lpc";
> +	#address-cells = <2>;
> +	#size-cells = <1>;
> +	reg = <0x0 0xa01b0000 0x0 0x1000>;
> +
> +	ipmi0: bt@e4 {
> +		compatible = "ipmi-bt";
> +		device_type = "ipmi";
> +		reg = <0x01 0xe4 0x04>;
> +	};
> +};
> diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
> index 57e011d..91debe4 100644
> --- a/drivers/bus/Kconfig
> +++ b/drivers/bus/Kconfig
> @@ -65,6 +65,14 @@ config BRCMSTB_GISB_ARB
>  	  arbiter. This driver provides timeout and target abort error handling
>  	  and internal bus master decoding.
>  
> +config HISILICON_LPC
> +	bool "Support for ISA I/O space on Hisilicon hip06/7"
> +	depends on (ARM64 && (ARCH_HISI || COMPILE_TEST))
> +	select INDIRECT_PIO
> +	help
> +	  Driver needed for some legacy ISA devices attached to Low-Pin-Count
> +	  on Hisilicon hip06/7 SoC.
> +
>  config IMX_WEIM
>  	bool "Freescale EIM DRIVER"
>  	depends on ARCH_MXC
> diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
> index 9bcd0bf..abc7a42 100644
> --- a/drivers/bus/Makefile
> +++ b/drivers/bus/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_ARM_CCI)		+= arm-cci.o
>  obj-$(CONFIG_ARM_CCN)		+= arm-ccn.o
>  
>  obj-$(CONFIG_BRCMSTB_GISB_ARB)	+= brcmstb_gisb.o
> +obj-$(CONFIG_HISILICON_LPC)	+= hisi_lpc.o
>  obj-$(CONFIG_IMX_WEIM)		+= imx-weim.o
>  obj-$(CONFIG_MIPS_CDMM)		+= mips_cdmm.o
>  obj-$(CONFIG_MVEBU_MBUS) 	+= mvebu-mbus.o
> diff --git a/drivers/bus/hisi_lpc.c b/drivers/bus/hisi_lpc.c
> new file mode 100644
> index 0000000..4ce089a
> --- /dev/null
> +++ b/drivers/bus/hisi_lpc.c
> @@ -0,0 +1,526 @@
> +/*
> + * Copyright (C) 2017 Hisilicon Limited, All Rights Reserved.
> + * Author: Zhichang Yuan <yuanzhichang@xxxxxxxxxxxxx>
> + * Author: Zou Rongrong <zourongrong@xxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/console.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/logic_pio.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/pci.h>
> +#include <linux/slab.h>
> +
> +#define LPC_MIN_BUS_RANGE	0x0
> +
> +/*
> + * The default maximal IO size for Hip06/Hip07 LPC bus.
> + * Defining the I/O range size as 0x4000 here should be sufficient for
> + * all peripherals under the bus.
> + */
> +#define LPC_BUS_IO_SIZE		0x4000
> +
> +/*
> + * Setting this bit means each IO operation will target to a
> + * different port address:
> + * 0 means repeatedly IO operations will stick on the same port,
> + * such as BT;
> + */
> +#define FG_INCRADDR_LPC		0x02
> +
> +struct lpc_cycle_para {
> +	unsigned int opflags;
> +	unsigned int csize; /* the data length of each operation */
> +};
> +
> +struct hisilpc_dev {
> +	spinlock_t cycle_lock;
> +	void __iomem  *membase;
> +	struct logic_pio_hwaddr *io_host;
> +};
> +
> +/* The maximum continuous cycles per burst */
> +#define LPC_MAX_BURST	16
> +/* The IO cycle counts supported is four per operation at maximum */
> +#define LPC_MAX_DULEN	4
> +#if LPC_MAX_DULEN > LPC_MAX_BURST
> +#error "LPC.. MAX_DULEN must be not bigger than MAX_OPCNT!"
> +#endif
> +
> +#if LPC_MAX_BURST % LPC_MAX_DULEN
> +#error "LPC.. LPC_MAX_BURST must be multiple of LPC_MAX_DULEN!"
> +#endif
> +
> +#define LPC_REG_START		0x00 /* start a new LPC cycle */
> +#define LPC_REG_OP_STATUS	0x04 /* the current LPC status */
> +#define LPC_REG_IRQ_ST		0x08 /* interrupt enable&status */
> +#define LPC_REG_OP_LEN		0x10 /* how many LPC cycles each start */
> +#define LPC_REG_CMD		0x14 /* command for the required LPC cycle */
> +#define LPC_REG_ADDR		0x20 /* LPC target address */
> +#define LPC_REG_WDATA		0x24 /* data to be written */
> +#define LPC_REG_RDATA		0x28 /* data coming from peer */
> +
> +
> +/* The command register fields */
> +#define LPC_CMD_SAMEADDR	0x08
> +#define LPC_CMD_TYPE_IO		0x00
> +#define LPC_CMD_WRITE		0x01
> +#define LPC_CMD_READ		0x00
> +/* the bit attribute is W1C. 1 represents OK. */
> +#define LPC_STAT_BYIRQ		0x02
> +
> +#define LPC_STATUS_IDLE		0x01
> +#define LPC_OP_FINISHED		0x02
> +
> +#define LPC_START_WORK		0x01
> +
> +/* The minimal nanosecond interval for each query on LPC cycle status. */
> +#define LPC_NSEC_PERWAIT	100
> +/*
> + * The maximum waiting time is about 128us.
> + * It is specific for stream I/O, such as ins.
> + * The fastest IO cycle time is about 390ns, but the worst case will wait
> + * for extra 256 lpc clocks, so (256 + 13) * 30ns = 8 us. The maximum
> + * burst cycles is 16. So, the maximum waiting time is about 128us under
> + * worst case.
> + * choose 1300 as the maximum.
> + */
> +#define LPC_MAX_WAITCNT		1300
> +/* About 10us. This is specific for single IO operation, such as inb. */
> +#define LPC_PEROP_WAITCNT	100
> +
> +static inline int wait_lpc_idle(unsigned char *mbase,
> +				unsigned int waitcnt) {
> +	u32 opstatus;
> +
> +	while (waitcnt--) {
> +		ndelay(LPC_NSEC_PERWAIT);
> +		opstatus = readl(mbase + LPC_REG_OP_STATUS);
> +		if (opstatus & LPC_STATUS_IDLE)
> +			return (opstatus & LPC_OP_FINISHED) ? 0 : (-EIO);
> +	}
> +	return -ETIME;
> +}
> +
> +/*
> + * hisilpc_target_in - trigger a series of lpc cycles to read required data
> + *		       from target peripheral.
> + * @lpcdev: pointer to hisi lpc device
> + * @para: some parameters used to control the lpc I/O operations
> + * @ptaddr: the lpc I/O target port address
> + * @buf: where the read back data is stored
> + * @opcnt: how many I/O operations required in this calling
> + *
> + * Only one byte data is read each I/O operation.
> + *
> + * Returns 0 on success, non-zero on fail.
> + */
> +static int
> +hisilpc_target_in(struct hisilpc_dev *lpcdev, struct lpc_cycle_para *para,
> +		  unsigned long ptaddr, unsigned char *buf,
> +		  unsigned long opcnt)
> +{
> +	unsigned long cnt_per_trans;
> +	unsigned int cmd_word;
> +	unsigned int waitcnt;
> +	int ret;
> +
> +	if (!buf || !opcnt || !para || !para->csize || !lpcdev)
> +		return -EINVAL;
> +
> +	cmd_word = LPC_CMD_TYPE_IO | LPC_CMD_READ;
> +	waitcnt = LPC_PEROP_WAITCNT;
> +	if (!(para->opflags & FG_INCRADDR_LPC)) {
> +		cmd_word |= LPC_CMD_SAMEADDR;
> +		waitcnt = LPC_MAX_WAITCNT;
> +	}
> +
> +	ret = 0;
> +	cnt_per_trans = (para->csize == 1) ? opcnt : para->csize;
> +	for (; opcnt && !ret; cnt_per_trans = para->csize) {
> +		unsigned long flags;
> +
> +		/* whole operation must be atomic */
> +		spin_lock_irqsave(&lpcdev->cycle_lock, flags);
> +
> +		writel_relaxed(cnt_per_trans, lpcdev->membase + LPC_REG_OP_LEN);
> +
> +		writel_relaxed(cmd_word, lpcdev->membase + LPC_REG_CMD);
> +
> +		writel_relaxed(ptaddr, lpcdev->membase + LPC_REG_ADDR);
> +
> +		writel(LPC_START_WORK, lpcdev->membase + LPC_REG_START);
> +
> +		/* whether the operation is finished */
> +		ret = wait_lpc_idle(lpcdev->membase, waitcnt);
> +		if (!ret) {
> +			opcnt -= cnt_per_trans;

Do we need to check for an underflow here?

> +			for (cnt_per_trans--; cnt_per_trans--; buf++)
> +				*buf = readb_relaxed(lpcdev->membase +
> +					LPC_REG_RDATA);
> +			*buf = readb(lpcdev->membase + LPC_REG_RDATA);
> +		}
> +
> +		spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
> +	}
> +
> +	return ret;
> +}
> +
> +/*
> + * hisilpc_target_out - trigger a series of lpc cycles to write required
> + *			data to target peripheral.
> + * @lpcdev: pointer to hisi lpc device
> + * @para: some parameters used to control the lpc I/O operations
> + * @ptaddr: the lpc I/O target port address
> + * @buf: where the data to be written is stored
> + * @opcnt: how many I/O operations required
> + *
> + * Only one byte data is read each I/O operation.

s/read/written/ ?

> + * Returns 0 on success, non-zero on fail.
> + *
> + */
> +static int
> +hisilpc_target_out(struct hisilpc_dev *lpcdev, struct lpc_cycle_para *para,
> +		   unsigned long ptaddr, const unsigned char *buf,
> +		   unsigned long opcnt)
> +{
> +	unsigned long cnt_per_trans;
> +	unsigned int cmd_word;
> +	unsigned int waitcnt;
> +	int ret;
> +
> +	if (!buf || !opcnt || !para || !lpcdev)
> +		return -EINVAL;
> +
> +	/* default is increasing address */
> +	cmd_word = LPC_CMD_TYPE_IO | LPC_CMD_WRITE;
> +	waitcnt = LPC_PEROP_WAITCNT;
> +	if (!(para->opflags & FG_INCRADDR_LPC)) {
> +		cmd_word |= LPC_CMD_SAMEADDR;
> +		waitcnt = LPC_MAX_WAITCNT;
> +	}
> +
> +	ret = 0;
> +	cnt_per_trans = (para->csize == 1) ? opcnt : para->csize;
> +	for (; opcnt && !ret; cnt_per_trans = para->csize) {
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&lpcdev->cycle_lock, flags);
> +
> +		writel_relaxed(cnt_per_trans, lpcdev->membase + LPC_REG_OP_LEN);
> +		writel_relaxed(cmd_word, lpcdev->membase + LPC_REG_CMD);
> +		writel_relaxed(ptaddr, lpcdev->membase + LPC_REG_ADDR);
> +
> +		opcnt -= cnt_per_trans;

Underflow check needed?

 -dann

> +		for (; cnt_per_trans--; buf++)
> +			writeb_relaxed(*buf, lpcdev->membase + LPC_REG_WDATA);
> +
> +		writel(LPC_START_WORK, lpcdev->membase + LPC_REG_START);
> +
> +		/* whether the operation is finished */
> +		ret = wait_lpc_idle(lpcdev->membase, waitcnt);
> +
> +		spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
> +	}
> +
> +	return ret;
> +}
> +
> +static inline unsigned long
> +hisi_lpc_pio_to_addr(struct hisilpc_dev *lpcdev, unsigned long pio)
> +{
> +	return pio - lpcdev->io_host->io_start +
> +		lpcdev->io_host->hw_start;
> +}
> +
> +
> +/**
> + * hisilpc_comm_in - read/input the data from the I/O peripheral
> + *		     through LPC.
> + * @devobj: pointer to the device information relevant to LPC controller.
> + * @pio: the target I/O port address.
> + * @dlen: the data length required to read from the target I/O port.
> + *
> + * when succeed, the data read back is stored in buffer pointed by inbuf.
> + * For inb, return the data read from I/O or -1 when error occur.
> + */
> +static u32 hisilpc_comm_in(void *devobj, unsigned long pio, size_t dlen)
> +{
> +	int ret = 0;
> +	unsigned char rd_data = 0;
> +	unsigned long ptaddr;
> +	struct lpc_cycle_para iopara;
> +	struct hisilpc_dev *lpcdev = devobj;
> +
> +	if (!lpcdev || !dlen || dlen > LPC_MAX_DULEN)
> +		return -1;
> +
> +	ptaddr = hisi_lpc_pio_to_addr(lpcdev, pio);
> +
> +	iopara.opflags = FG_INCRADDR_LPC;
> +	iopara.csize = dlen;
> +
> +	ret = hisilpc_target_in(lpcdev, &iopara, ptaddr, &rd_data, dlen);
> +	if (ret)
> +		return -1;
> +
> +	return le32_to_cpu((u32)rd_data);
> +}
> +
> +/**
> + * hisilpc_comm_out - output the data whose maximum length is four bytes
> +		      to the I/O peripheral through the LPC host.
> + * @devobj: pointer to the device information relevant to LPC controller.
> + * @pio: the target I/O port address.
> + * @outval: a value to be outputted from caller, maximum is four bytes.
> + * @dlen: the data length required writing to the target I/O port.
> + *
> + * This function is corresponding to out(b,w,l) only
> + *
> + */
> +static void hisilpc_comm_out(void *devobj, unsigned long pio,
> +			     u32 outval, size_t dlen)
> +{
> +	unsigned long ptaddr;
> +	struct hisilpc_dev *lpcdev = devobj;
> +	struct lpc_cycle_para iopara;
> +	const unsigned char *newbuf;
> +
> +	if (!lpcdev || !dlen || dlen > LPC_MAX_DULEN)
> +		return;
> +
> +	outval = cpu_to_le32(outval);
> +
> +	newbuf = (const unsigned char *)&outval;
> +	ptaddr = hisi_lpc_pio_to_addr(lpcdev, pio);
> +
> +	iopara.opflags = FG_INCRADDR_LPC;
> +	iopara.csize = dlen;
> +
> +	hisilpc_target_out(lpcdev, &iopara, ptaddr, newbuf, dlen);
> +}
> +
> +/*
> + * hisilpc_comm_ins - read/input the data in buffer to the I/O
> + *		peripheral through LPC, it corresponds to ins(b,w,l)
> + * @devobj: pointer to the device information relevant to LPC controller.
> + * @pio: the target I/O port address.
> + * @inbuf: a buffer where read/input data bytes are stored.
> + * @dlen: the data length required writing to the target I/O port.
> + * @count: how many data units whose length is dlen will be read.
> + *
> + * when succeed, the data read back is stored in buffer pointed by inbuf.
> + * Returns 0 on success, -errno otherwise
> + *
> + */
> +static u32
> +hisilpc_comm_ins(void *devobj, unsigned long pio, void *inbuf,
> +		 size_t dlen, unsigned int count)
> +{
> +	struct hisilpc_dev *lpcdev = devobj;
> +	struct lpc_cycle_para iopara;
> +	unsigned char *newbuf;
> +	unsigned int loopcnt, cntleft;
> +	unsigned long ptaddr;
> +
> +	if (!lpcdev || !inbuf || !count || !dlen || dlen > LPC_MAX_DULEN ||
> +			count % dlen)
> +		return -EINVAL;
> +
> +	iopara.opflags = 0;
> +	if (dlen > 1)
> +		iopara.opflags |= FG_INCRADDR_LPC;
> +	iopara.csize = dlen;
> +
> +	ptaddr = hisi_lpc_pio_to_addr(lpcdev, pio);
> +	newbuf = inbuf;
> +	/*
> +	 * ensure data stream whose length is multiple of dlen to be processed
> +	 * each IO input
> +	 */
> +	cntleft = count * dlen;
> +	do {
> +		int ret;
> +
> +		loopcnt = min_t(unsigned int, LPC_MAX_BURST, cntleft);
> +		ret = hisilpc_target_in(lpcdev, &iopara, ptaddr,
> +					newbuf, loopcnt);
> +		if (ret)
> +			return ret;
> +		newbuf += loopcnt;
> +		cntleft -= loopcnt;
> +	} while (cntleft);
> +
> +	return 0;
> +}
> +
> +/*
> + * hisilpc_comm_outs - write/output the data in buffer to the I/O
> + *		peripheral through LPC, it corresponds to outs(b,w,l)
> + * @devobj: pointer to the device information relevant to LPC controller.
> + * @pio: the target I/O port address.
> + * @outbuf: a buffer where write/output data bytes are stored.
> + * @dlen: the data length required writing to the target I/O port .
> + * @count: how many data units whose length is dlen will be written.
> + *
> + */
> +static void
> +hisilpc_comm_outs(void *devobj, unsigned long pio, const void *outbuf,
> +		  size_t dlen, unsigned int count)
> +{
> +	struct hisilpc_dev *lpcdev = devobj;
> +	struct lpc_cycle_para iopara;
> +	const unsigned char *newbuf;
> +	unsigned int loopcnt, cntleft;
> +	unsigned long ptaddr;
> +
> +	if (!lpcdev || !outbuf || !count || !dlen || dlen > LPC_MAX_DULEN ||
> +			count % dlen)
> +		return;
> +
> +	iopara.opflags = 0;
> +	if (dlen > 1)
> +		iopara.opflags |= FG_INCRADDR_LPC;
> +	iopara.csize = dlen;
> +
> +	ptaddr = hisi_lpc_pio_to_addr(lpcdev, pio);
> +	newbuf = outbuf;
> +	/*
> +	 * ensure data stream whose length is multiple of dlen to be processed
> +	 * each IO input
> +	 */
> +	cntleft = count * dlen;
> +	do {
> +		loopcnt = min_t(unsigned int, LPC_MAX_BURST, cntleft);
> +		if (hisilpc_target_out(lpcdev, &iopara, ptaddr, newbuf,
> +						loopcnt))
> +			break;
> +		newbuf += loopcnt;
> +		cntleft -= loopcnt;
> +	} while (cntleft);
> +}
> +
> +static struct hostio_ops hisi_lpc_ops = {
> +	.pfin = hisilpc_comm_in,
> +	.pfout = hisilpc_comm_out,
> +	.pfins = hisilpc_comm_ins,
> +	.pfouts = hisilpc_comm_outs,
> +};
> +
> +/**
> + * hisilpc_probe - the probe callback function for hisi lpc device,
> + *		   will finish all the initialization.
> + * @pdev: the platform device corresponding to hisi lpc
> + *
> + * Returns 0 on success, non-zero on fail.
> + */
> +static int hisilpc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +	struct hisilpc_dev *lpcdev;
> +	int ret = 0;
> +
> +	lpcdev = devm_kzalloc(dev, sizeof(struct hisilpc_dev), GFP_KERNEL);
> +	if (!lpcdev)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&lpcdev->cycle_lock);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENODEV;
> +
> +	lpcdev->membase = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(lpcdev->membase)) {
> +		dev_err(dev, "remap failed\n");
> +		return PTR_ERR(lpcdev->membase);
> +	}
> +
> +	/* register the LPC host PIO resources */
> +	{
> +		struct logic_pio_hwaddr *range;
> +
> +		range = devm_kzalloc(dev, sizeof(*range), GFP_KERNEL);
> +		if (!range)
> +			return -ENOMEM;
> +		range->fwnode = dev->fwnode;
> +		range->flags = PIO_INDIRECT;
> +		range->size = LPC_BUS_IO_SIZE;
> +		range->hw_start = LPC_MIN_BUS_RANGE;
> +
> +		ret = logic_pio_register_range(range);
> +		if (ret) {
> +			kfree(range);
> +			dev_err(dev, "register IO range failed (%d)!\n", ret);
> +			return -ret;
> +		}
> +		lpcdev->io_host = range;
> +
> +		/*
> +		 * It is time to start the children scanning:
> +		 * For ACPI children, the corresponding devices had been
> +		 * created during the ACPI enumeration.
> +		 * The OF scanning must be performed after initialization of
> +		 * 'lpcdev' to avoid some children which complete the scanning
> +		 * trigger the MMIO accesses which will probably cause a panic.
> +		 */
> +		ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
> +		if (ret) {
> +			/*
> +			 * When LPC probing is not completely successful, set
> +			 * 'devpara' as NULL. This will make all the LPC I/O
> +			 * return failure directly without any hardware
> +			 * operations. It will prevent some peripherals which
> +			 * had not finished the initialization to manipulate
> +			 * I/O for safety.
> +			 */
> +			lpcdev->io_host->devpara = NULL;
> +			dev_err(dev, "populate children failed(%d)\n", ret);
> +			return ret;
> +		}
> +	}
> +	lpcdev->io_host->devpara = lpcdev;
> +	lpcdev->io_host->ops = &hisi_lpc_ops;
> +
> +	dev_info(dev, "registered range[%pa - sz:%pa]\n",
> +		 &lpcdev->io_host->io_start,
> +		 &lpcdev->io_host->size);
> +
> +	return ret;
> +}
> +
> +static const struct of_device_id hisilpc_of_match[] = {
> +	{ .compatible = "hisilicon,hip06-lpc", },
> +	{ .compatible = "hisilicon,hip07-lpc", },
> +	{},
> +};
> +
> +static struct platform_driver hisilpc_driver = {
> +	.driver = {
> +		.name           = "hisi_lpc",
> +		.of_match_table = hisilpc_of_match,
> +	},
> +	.probe = hisilpc_probe,
> +};
> +
> +builtin_platform_driver(hisilpc_driver);