Message-ID: <20180214161635.GA13849@e107981-ln.cambridge.arm.com>
Date:   Wed, 14 Feb 2018 16:16:35 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     John Garry <john.garry@...wei.com>
Cc:     mika.westerberg@...ux.intel.com, rafael@...nel.org,
        rjw@...ysocki.net, hanjun.guo@...aro.org, robh+dt@...nel.org,
        bhelgaas@...gle.com, arnd@...db.de, mark.rutland@....com,
        olof@...om.net, dann.frazier@...onical.com,
        andy.shevchenko@...il.com, robh@...nel.org, joe@...ches.com,
        benh@...nel.crashing.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linuxarm@...wei.com, minyard@....org, devicetree@...r.kernel.org,
        linux-arch@...r.kernel.org, rdunlap@...radead.org
Subject: Re: [PATCH v13 7/9] ACPI: Translate the I/O range of non-MMIO
 devices before scanning

On Wed, Feb 14, 2018 at 01:45:31AM +0800, John Garry wrote:
> On some platforms (such as arm64-based hip06/hip07), access to legacy
> ISA/LPC devices through access IO space is required, similar to x86
> platforms. As the I/O for these devices are not memory mapped like
> PCI/PCIE MMIO host bridges, they require special low-level device
> operations through some host to generate IO accesses, i.e. a non-
> transparent bridge.
> 
> Through the logical PIO framework, hosts are able to register address
> ranges in the logical PIO space for IO accesses. For hosts which require
> a LLDD to generate the IO accesses, through the logical PIO framework
> the host also registers accessors as a backend to generate the physical
> bus transactions for IO space accesses (called indirect IO).
> 
> When describing the indirect IO child device in APCI tables, the IO
> resource is the host-specific address for the child (generally a
> bus address).
> An example is as follows:
>   Device (LPC0) {
>     Name (_HID, "HISI0191")  // HiSi LPC
>     Name (_CRS, ResourceTemplate () {
>       Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
>     })
>   }
> 
>   Device (LPC0.IPMI) {
>     Name (_HID, "IPI0001")
>     Name (LORS, ResourceTemplate() {
>       QWordIO (
>         ResourceConsumer,
> 	MinNotFixed,     // _MIF
> 	MaxNotFixed,     // _MAF
> 	PosDecode,
> 	EntireRange,
> 	0x0,             // _GRA
> 	0xe4,            // _MIN
> 	0x3fff,          // _MAX
> 	0x0,             // _TRA
> 	0x04,            // _LEN
> 	, ,
> 	BTIO
>       )
>     })
> 
> Since the IO resource for the child is a host-specific address,
> special translation are required to retrieve the logical PIO address
> for that child.

The problem I have with this patchset and with pretending that the ACPI
bits are generic is that the rules used to translate resources (I am
referring to LPC0.IPMI above) are documented _nowhere_ which means that
making this series generic code is just wishful thinking - there are no
bindings backing it, it will never ever be used on a platform different
from the one you are pushing this code for and I stated this already.

Reworded differently - this is a Hisilicon driver it is not generic ACPI
code; I can't see how it can be used on a multitude of platforms unless
you specify FW level bindings.

> To overcome the problem of associating this logical PIO address
> with the child device, a scan handler is added to scan the ACPI
> namespace for known indirect IO hosts. This scan handler creates an
> MFD per child with the translated logical PIO address as it's IO
> resource, as a substitute for the normal platform device which ACPI
> would create during device enumeration.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> Signed-off-by: Zhichang Yuan <yuanzhichang@...ilicon.com>
> Signed-off-by: Gabriele Paoloni <gabriele.paoloni@...wei.com>
> ---
>  drivers/acpi/arm64/Makefile          |   1 +
>  drivers/acpi/arm64/acpi_indirectio.c | 250 +++++++++++++++++++++++++++++++++++

See above (and I do not understand what arm64 has to do with it).

I understand you need to find a place to add the:

acpi_indirect_io_scan_init()

to be called from core ACPI code because ACPI can't handle probe
dependencies in any other way but other than that this patch is
a Hisilicon ACPI driver - there is nothing generic in it (or at
least there are no standard bindings to make it so).

Whether a callback from ACPI core code (acpi_scan_init()) to a driver
specific hook is sane or not that's the question and the only reason
why you want to add this in drivers/acpi/arm64 rather than, say,
drivers/bus (as you do for the DT driver).

I do not know Rafael's opinion on the above, I would like to help
you make forward progress but please understand my concerns, mostly
on FW side.

Thanks,
Lorenzo

>  drivers/acpi/internal.h              |   5 +
>  drivers/acpi/scan.c                  |   1 +
>  4 files changed, 257 insertions(+)
>  create mode 100644 drivers/acpi/arm64/acpi_indirectio.c
> 
> diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
> index 1017def..f4a7f46 100644
> --- a/drivers/acpi/arm64/Makefile
> +++ b/drivers/acpi/arm64/Makefile
> @@ -1,2 +1,3 @@
>  obj-$(CONFIG_ACPI_IORT) 	+= iort.o
>  obj-$(CONFIG_ACPI_GTDT) 	+= gtdt.o
> +obj-$(CONFIG_INDIRECT_PIO)	+= acpi_indirectio.o
> diff --git a/drivers/acpi/arm64/acpi_indirectio.c b/drivers/acpi/arm64/acpi_indirectio.c
> new file mode 100644
> index 0000000..51a1b92
> --- /dev/null
> +++ b/drivers/acpi/arm64/acpi_indirectio.c
> @@ -0,0 +1,250 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2017 HiSilicon Limited, All Rights Reserved.
> + * Author: Gabriele Paoloni <gabriele.paoloni@...wei.com>
> + * Author: Zhichang Yuan <yuanzhichang@...ilicon.com>
> + * Author: John Garry <john.garry@...wei.com>
> + *
> + * This file implements functunality to scan the ACPI namespace and config
> + * devices under "indirect IO" hosts. An "indirect IO" host allows child
> + * devices to use logical IO accesses when the host, itself, does not provide
> + * a transparent bridge. The device setup creates a per-child MFD with a
> + * logical port IO resource.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/logic_pio.h>
> +#include <linux/mfd/core.h>
> +#include <linux/platform_device.h>
> +
> +ACPI_MODULE_NAME("indirect IO");
> +
> +#define ACPI_INDIRECT_IO_NAME_LEN 255
> +
> +struct acpi_indirect_io_mfd_cell {
> +	struct mfd_cell_acpi_match acpi_match;
> +	char name[ACPI_INDIRECT_IO_NAME_LEN];
> +	char pnpid[ACPI_INDIRECT_IO_NAME_LEN];
> +};
> +
> +static int acpi_indirect_io_xlat_res(struct acpi_device *adev,
> +				     struct acpi_device *host,
> +				     struct resource *res)
> +{
> +	unsigned long sys_port;
> +	resource_size_t len = res->end - res->start;
> +
> +	sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
> +	if (sys_port == -1UL)
> +		return -EFAULT;
> +
> +	res->start = sys_port;
> +	res->end = sys_port + len;
> +
> +	return 0;
> +}
> +
> +/*
> + * acpi_indirect_io_set_res - set the resources for a child device
> + * (MFD) of an "indirect IO" host.
> + * @child: the device node to be updated the I/O resource
> + * @hostdev: the device node associated with the "indirect IO" host
> + * @res: double pointer to be set to the address of translated resources
> + * @num_res: pointer to variable to hold the number of translated resources
> + *
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * For a given "indirect IO" host, each child device will have associated
> + * host-relevative address resource. This function will return the translated
> + * logical PIO addresses for each child devices resources.
> + */
> +static int acpi_indirect_io_set_res(struct device *child,
> +				    struct device *hostdev,
> +				    const struct resource **res,
> +				    int *num_res)
> +{
> +	struct acpi_device *adev;
> +	struct acpi_device *host;
> +	struct resource_entry *rentry;
> +	LIST_HEAD(resource_list);
> +	struct resource *resources;
> +	int count;
> +	int i;
> +	int ret = -EIO;
> +
> +	if (!child || !hostdev)
> +		return -EINVAL;
> +
> +	host = to_acpi_device(hostdev);
> +	adev = to_acpi_device(child);
> +
> +	/* check the device state */
> +	if (!adev->status.present) {
> +		dev_info(child, "device is not present\n");
> +		return 0;
> +	}
> +	/* whether the child had been enumerated? */
> +	if (acpi_device_enumerated(adev)) {
> +		dev_info(child, "had been enumerated\n");
> +		return 0;
> +	}
> +
> +	count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
> +	if (count <= 0) {
> +		dev_err(child, "failed to get resources\n");
> +		return count ? count : -EIO;
> +	}
> +
> +	resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
> +	if (!resources) {
> +		acpi_dev_free_resource_list(&resource_list);
> +		return -ENOMEM;
> +	}
> +	count = 0;
> +	list_for_each_entry(rentry, &resource_list, node)
> +		resources[count++] = *rentry->res;
> +
> +	acpi_dev_free_resource_list(&resource_list);
> +
> +	/* translate the I/O resources */
> +	for (i = 0; i < count; i++) {
> +		if (!(resources[i].flags & IORESOURCE_IO))
> +			continue;
> +		ret = acpi_indirect_io_xlat_res(adev, host, &resources[i]);
> +		if (ret) {
> +			kfree(resources);
> +			dev_err(child, "translate IO range failed(%d)\n", ret);
> +			return ret;
> +		}
> +	}
> +	*res = resources;
> +	*num_res = count;
> +
> +	return ret;
> +}
> +
> +/*
> + * acpi_indirect_io_setup - scan handler for "indirect IO" host.
> + * @adev: "indirect IO" host ACPI device pointer
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * Setup an "indirect IO" host by scanning all child devices, and
> + * create a per-device MFD with logical PIO translated IO resources.
> + */
> +static int acpi_indirect_io_setup(struct acpi_device *adev)
> +{
> +	struct platform_device *pdev;
> +	struct mfd_cell *mfd_cells;
> +	struct logic_pio_hwaddr *range;
> +	struct acpi_device *child;
> +	struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cells;
> +	int size, ret, count = 0, cell_num = 0;
> +
> +	range = kzalloc(sizeof(*range), GFP_KERNEL);
> +	if (!range)
> +		return -ENOMEM;
> +	range->fwnode = &adev->fwnode;
> +	range->flags = PIO_INDIRECT;
> +	range->size = PIO_INDIRECT_SIZE;
> +
> +	ret = logic_pio_register_range(range);
> +	if (ret)
> +		goto free_range;
> +
> +	list_for_each_entry(child, &adev->children, node)
> +		cell_num++;
> +
> +	/* allocate the mfd cell and companion acpi info, one per child */
> +	size = sizeof(*mfd_cells) + sizeof(*acpi_indirect_io_mfd_cells);
> +	mfd_cells = kcalloc(cell_num, size, GFP_KERNEL);
> +	if (!mfd_cells) {
> +		ret = -ENOMEM;
> +		goto free_range;
> +	}
> +
> +	acpi_indirect_io_mfd_cells = (struct acpi_indirect_io_mfd_cell *)
> +					&mfd_cells[cell_num];
> +	/* Only consider the children of the host */
> +	list_for_each_entry(child, &adev->children, node) {
> +		struct mfd_cell *mfd_cell = &mfd_cells[count];
> +		struct acpi_indirect_io_mfd_cell *acpi_indirect_io_mfd_cell =
> +					&acpi_indirect_io_mfd_cells[count];
> +		const struct mfd_cell_acpi_match *acpi_match =
> +					&acpi_indirect_io_mfd_cell->acpi_match;
> +		char *name = &acpi_indirect_io_mfd_cell[count].name[0];
> +		char *pnpid = &acpi_indirect_io_mfd_cell[count].pnpid[0];
> +		struct mfd_cell_acpi_match match = {
> +			.pnpid = pnpid,
> +		};
> +
> +		snprintf(name, ACPI_INDIRECT_IO_NAME_LEN, "indirect-io-%s",
> +			 acpi_device_hid(child));
> +		snprintf(pnpid, ACPI_INDIRECT_IO_NAME_LEN, "%s",
> +			 acpi_device_hid(child));
> +
> +		memcpy((void *)acpi_match, (void *)&match, sizeof(*acpi_match));
> +		mfd_cell->name = name;
> +		mfd_cell->acpi_match = acpi_match;
> +
> +		ret = acpi_indirect_io_set_res(&child->dev, &adev->dev,
> +					       &mfd_cell->resources,
> +					       &mfd_cell->num_resources);
> +		if (ret) {
> +			dev_err(&child->dev, "set resource failed (%d)\n", ret);
> +			goto free_mfd_resources;
> +		}
> +		count++;
> +	}
> +
> +	pdev = acpi_create_platform_device(adev, NULL);
> +	if (IS_ERR_OR_NULL(pdev)) {
> +		dev_err(&adev->dev, "create platform device for host failed\n");
> +		ret = PTR_ERR(pdev);
> +		goto free_mfd_resources;
> +	}
> +	acpi_device_set_enumerated(adev);
> +
> +	ret = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
> +			      mfd_cells, cell_num, NULL, 0, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to add mfd cells (%d)\n", ret);
> +		goto free_mfd_resources;
> +	}
> +
> +	return ret;
> +
> +free_mfd_resources:
> +	while (cell_num--)
> +		kfree(mfd_cells[cell_num].resources);
> +	kfree(mfd_cells);
> +free_range:
> +	kfree(range);
> +
> +	return ret;
> +}
> +
> +/* All the host devices which apply indirect-IO can be listed here. */
> +static const struct acpi_device_id acpi_indirect_io_host_id[] = {
> +	{}
> +};
> +
> +static int acpi_indirect_io_attach(struct acpi_device *adev,
> +				   const struct acpi_device_id *id)
> +{
> +	int ret = acpi_indirect_io_setup(adev);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return 1;
> +}
> +
> +static struct acpi_scan_handler acpi_indirect_io_handler = {
> +	.ids = acpi_indirect_io_host_id,
> +	.attach = acpi_indirect_io_attach,
> +};
> +
> +void __init acpi_indirect_io_scan_init(void)
> +{
> +	acpi_scan_add_handler(&acpi_indirect_io_handler);
> +}
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 1d0a501..680f3cf 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -31,6 +31,11 @@
>  void acpi_platform_init(void);
>  void acpi_pnp_init(void);
>  void acpi_int340x_thermal_init(void);
> +#ifdef CONFIG_INDIRECT_PIO
> +void acpi_indirect_io_scan_init(void);
> +#else
> +static inline void acpi_indirect_io_scan_init(void) {}
> +#endif
>  #ifdef CONFIG_ARM_AMBA
>  void acpi_amba_init(void);
>  #else
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 8e63d93..204da8a 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -2155,6 +2155,7 @@ int __init acpi_scan_init(void)
>  	acpi_amba_init();
>  	acpi_watchdog_init();
>  	acpi_init_lpit();
> +	acpi_indirect_io_scan_init();
>  
>  	acpi_scan_add_handler(&generic_device_handler);
>  
> -- 
> 1.9.1
> 

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