Re: [PATCH v2] drivers/misc: Add ASpeed LPC control driver

[Cyril Bur <cyrilbur@gmail.com>]

On Fri, 2017-01-13 at 11:36 +0100, Greg KH wrote:
> On Fri, Jan 13, 2017 at 06:47:13PM +1100, Cyril Bur wrote:
> > +config ASPEED_LPC_CTRL
> > +	depends on (ARCH_ASPEED || COMPILE_TEST) && REGMAP && MFD_SYSCON
> > +	bool "Build a driver to control the BMC to HOST LPC bus"
> > +	default "y"
> 
> Unless a kernel option prevents a machine from booting, it should never
> be 'default y'.  This is a misc driver, it should never be 'default y'.
> 

Hi Greg,

Yes, I think I was convinced otherwise. I'll change.

> 
> > --- /dev/null
> > +++ b/drivers/misc/aspeed-lpc-ctrl.c
> > @@ -0,0 +1,264 @@
> > +/*
> > + * Copyright 2017 IBM 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.
> 
> I have to ask, do you really mean "any later version"?
> 

I appreciate that you checked - I can confirm that I do mean "any later
version"

> > + */
> > +
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/miscdevice.h>
> > +#include <linux/mm.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/poll.h>
> > +#include <linux/regmap.h>
> > +
> > +#include <linux/aspeed-lpc-ctrl.h>
> > +
> > +#define DEVICE_NAME	"aspeed-lpc-ctrl"
> > +
> > +#define HICR7 0x8
> > +#define HICR8 0xc
> > +
> > +struct aspeed_lpc_ctrl {
> > +	struct miscdevice	miscdev;
> > +	struct regmap		*regmap;
> > +	phys_addr_t		mem_base;
> > +	resource_size_t		mem_size;
> > +	__u32		pnor_size;
> > +	__u32		pnor_base;
> > +};
> > +
> > +static struct aspeed_lpc_ctrl *file_aspeed_lpc_ctrl(struct file *file)
> > +{
> > +	return container_of(file->private_data, struct aspeed_lpc_ctrl,
> > +			miscdev);
> > +}
> > +
> > +static int aspeed_lpc_ctrl_mmap(struct file *file, struct vm_area_struct *vma)
> > +{
> > +	struct aspeed_lpc_ctrl *lpc_ctrl = file_aspeed_lpc_ctrl(file);
> > +	unsigned long vsize = vma->vm_end - vma->vm_start;
> > +	pgprot_t prot = vma->vm_page_prot;
> > +
> > +	if (vma->vm_pgoff + vsize > lpc_ctrl->mem_base + lpc_ctrl->mem_size)
> > +		return -EINVAL;
> > +
> > +	/* AHB access are not cache coherent */
> > +	if (file->f_flags & O_DSYNC)
> > +		prot = pgprot_noncached(prot);
> > +
> > +	if (remap_pfn_range(vma, vma->vm_start,
> > +		(lpc_ctrl->mem_base >> PAGE_SHIFT) + vma->vm_pgoff,
> > +		vsize, prot))
> > +		return -EAGAIN;
> > +
> > +	return 0;
> > +}
> > +
> > +static long aspeed_lpc_ctrl_ioctl(struct file *file, unsigned int cmd,
> > +		unsigned long param)
> > +{
> > +	long rc;
> > +	struct aspeed_lpc_ctrl_mapping map;
> > +	struct aspeed_lpc_ctrl *lpc_ctrl = file_aspeed_lpc_ctrl(file);
> > +	void __user *p = (void __user *)param;
> > +	u32 addr;
> > +	u32 size;
> > +
> > +	if (copy_from_user(&map, p, sizeof(map)))
> > +		return -EFAULT;
> > +
> > +	switch (cmd) {
> > +	case ASPEED_LPC_CTRL_IOCTL_GET_SIZE:
> > +		/* The flash windows don't report their size */
> > +		if (map.window_type != ASPEED_LPC_CTRL_WINDOW_MEMORY)
> > +			return -EINVAL;
> > +
> > +		/* Support more than one window id in the future */
> > +		if (map.window_id != 0)
> > +			return -EINVAL;
> > +
> > +		map.size = lpc_ctrl->mem_size;
> > +
> > +		return copy_to_user(p, &map, sizeof(map)) ? -EFAULT : 0;
> > +	case ASPEED_LPC_CTRL_IOCTL_MAP:
> > +
> > +		/*
> > +		 * The top half of HICR7 is the MSB of the BMC address of the
> > +		 * mapping.
> > +		 * The bottom half of HICR7 is the MSB of the HOST LPC
> > +		 * firmware space address of the mapping.
> > +		 *
> > +		 * The 1 bits in the top of half of HICR8 represent the bits
> > +		 * (in the requested address) that should be ignored and
> > +		 * replaced with those from the top half of HICR7.
> > +		 * The 1 bits in the bottom half of HICR8 represent the bits
> > +		 * (in the requested address) that should be kept and pass
> > +		 * into the BMC address space.
> > +		 */
> > +
> > +		/*
> > +		 * It doesn't make sense to talk about a size or offset with
> > +		 * low 16 bits set. Both HICR7 and HICR8 talk about the top 16
> > +		 * bits of addresses and sizes.
> > +		 */
> > +
> > +		if ((map.size & 0x0000ffff) || (map.offset & 0x0000ffff))
> > +			return -EINVAL;
> > +
> > +		/*
> > +		 * Because of the way the masks work in HICR8 offset has to
> > +		 * be a multiple of size
> > +		 */
> > +		if (map.offset & (map.size - 1))
> > +			return -EINVAL;
> > +
> > +		if (map.window_type == ASPEED_LPC_CTRL_WINDOW_FLASH) {
> > +			addr = lpc_ctrl->pnor_base;
> > +			size = lpc_ctrl->pnor_size;
> > +		} else if (map.window_type == ASPEED_LPC_CTRL_WINDOW_MEMORY) {
> > +			addr = lpc_ctrl->mem_base;
> > +			size = lpc_ctrl->mem_size;
> > +		} else {
> > +			return -EINVAL;
> > +		}
> > +
> > +		/* Overflow first! */
> > +		if (map.offset + map.size < map.offset ||
> > +			map.offset + map.size > size)
> > +			return -EINVAL;
> > +
> > +		if (map.size == 0 || map.size > size)
> > +			return -EINVAL;
> > +
> > +		addr += map.offset;
> > +
> > +		/*
> > +		 * hostaddr is safe regardless of values. This simply changes
> > +		 * the address the host has to request on its side of the LPC
> > +		 * bus. This cannot impact the hosts own memory space by
> > +		 * surprise as LPC specific accessors are required. The only
> > +		 * strange thing that could be done is setting the lower 16
> > +		 * bits but the shift takes care of that.
> > +		 */
> > +
> > +		rc = regmap_write(lpc_ctrl->regmap, HICR7,
> > +				(addr | (map.addr >> 16)));
> > +		if (rc)
> > +			return rc;
> > +
> > +		return regmap_write(lpc_ctrl->regmap, HICR8,
> > +			(~(map.size - 1)) | ((map.size >> 16) - 1));
> > +	}
> > +
> > +	return -EINVAL;
> > +}
> > +
> > +static const struct file_operations aspeed_lpc_ctrl_fops = {
> > +	.owner		= THIS_MODULE,
> > +	.mmap		= aspeed_lpc_ctrl_mmap,
> > +	.unlocked_ioctl	= aspeed_lpc_ctrl_ioctl,
> > +};
> > +
> > +static int aspeed_lpc_ctrl_probe(struct platform_device *pdev)
> > +{
> > +	struct aspeed_lpc_ctrl *lpc_ctrl;
> > +	struct device *dev;
> > +	struct device_node *node;
> > +	struct resource resm;
> > +	int rc;
> > +
> > +	dev = &pdev->dev;
> > +
> > +	lpc_ctrl = devm_kzalloc(dev, sizeof(*lpc_ctrl), GFP_KERNEL);
> > +	if (!lpc_ctrl)
> > +		return -ENOMEM;
> > +
> > +	node = of_parse_phandle(dev->of_node, "flash", 0);
> > +	if (!node) {
> > +		dev_err(dev, "Didn't find host pnor flash node\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	rc = of_property_read_u32_index(node, "reg", 3,
> > +			&lpc_ctrl->pnor_size);
> > +	if (rc)
> > +		return rc;
> > +	rc = of_property_read_u32_index(node, "reg", 2,
> > +			&lpc_ctrl->pnor_base);
> > +	if (rc)
> > +		return rc;
> > +
> > +	dev_set_drvdata(&pdev->dev, lpc_ctrl);
> > +
> > +	node = of_parse_phandle(dev->of_node, "memory-region", 0);
> > +	if (!node) {
> > +		dev_err(dev, "Didn't find reserved memory\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	rc = of_address_to_resource(node, 0, &resm);
> > +	of_node_put(node);
> > +	if (rc) {
> > +		dev_err(dev, "Could address to resource\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	lpc_ctrl->mem_size = resource_size(&resm);
> > +	lpc_ctrl->mem_base = resm.start;
> > +
> > +	lpc_ctrl->regmap = syscon_node_to_regmap(
> > +			pdev->dev.parent->of_node);
> > +	if (IS_ERR(lpc_ctrl->regmap)) {
> > +		dev_err(dev, "Couldn't get regmap\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	lpc_ctrl->miscdev.minor = MISC_DYNAMIC_MINOR;
> > +	lpc_ctrl->miscdev.name = DEVICE_NAME;
> > +	lpc_ctrl->miscdev.fops = &aspeed_lpc_ctrl_fops;
> > +	lpc_ctrl->miscdev.parent = dev;
> > +	rc = misc_register(&lpc_ctrl->miscdev);
> > +	if (rc)
> > +		dev_err(dev, "Unable to register device\n");
> > +	else
> > +		dev_info(dev, "Loaded at 0x%08x (0x%08x)\n",
> > +			lpc_ctrl->mem_base, lpc_ctrl->mem_size);
> > +
> > +	return rc;
> > +}
> > +
> > +static int aspeed_lpc_ctrl_remove(struct platform_device *pdev)
> > +{
> > +	struct aspeed_lpc_ctrl *lpc_ctrl = dev_get_drvdata(&pdev->dev);
> > +
> > +	misc_deregister(&lpc_ctrl->miscdev);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id aspeed_lpc_ctrl_match[] = {
> > +	{ .compatible = "aspeed,ast2400-lpc-ctrl" },
> > +	{ .compatible = "aspeed,ast2500-lpc-ctrl" },
> > +	{ },
> > +};
> > +
> > +static struct platform_driver aspeed_lpc_ctrl_driver = {
> > +	.driver = {
> > +		.name		= DEVICE_NAME,
> > +		.of_match_table = aspeed_lpc_ctrl_match,
> > +	},
> > +	.probe = aspeed_lpc_ctrl_probe,
> > +	.remove = aspeed_lpc_ctrl_remove,
> > +};
> > +
> > +module_platform_driver(aspeed_lpc_ctrl_driver);
> > +
> > +MODULE_DEVICE_TABLE(of, aspeed_lpc_ctrl_match);
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Cyril Bur <cyrilbur@gmail.com>");
> > +MODULE_DESCRIPTION("Linux device interface to control LPC bus");
> > diff --git a/include/uapi/linux/aspeed-lpc-ctrl.h b/include/uapi/linux/aspeed-lpc-ctrl.h
> > new file mode 100644
> > index 000000000000..220220b6c83a
> > --- /dev/null
> > +++ b/include/uapi/linux/aspeed-lpc-ctrl.h
> > @@ -0,0 +1,35 @@
> > +/*
> > + * Copyright 2017 IBM Corp.
> > + *
> > + * 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_ASPEED_LPC_CTRL_H
> > +#define _UAPI_LINUX_ASPEED_LPC_CTRL_H
> > +
> > +#include <linux/ioctl.h>
> > +
> > +/* Window types */
> > +#define ASPEED_LPC_CTRL_WINDOW_FLASH	1
> > +#define ASPEED_LPC_CTRL_WINDOW_MEMORY	2
> > +
> > +struct aspeed_lpc_ctrl_mapping {
> > +	__u8	window_type;
> > +	__u8	window_id;
> > +	__u32	addr;
> > +	__u32	offset;
> > +	__u32	size;
> 
> That's some crazy alignment, do you really mean to put a 32bit value
> aligned like that?  Will it work properly on your systems?
> 

Well, in my probably unrealistic and rushed testing it did work - but
then this was all with one compiler on one machine so I'm not
surprised. I'll put the u8s at the end.

Thanks,

Cyril


> thanks,
> 
> greg k-h