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Date: Wed, 14 Feb 2018 15:53:21 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: John Garry <john.garry@...wei.com>
Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Hanjun Guo <hanjun.guo@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Arnd Bergmann <arnd@...db.de>,
Mark Rutland <mark.rutland@....com>,
Olof Johansson <olof@...om.net>,
Dann Frazier <dann.frazier@...onical.com>,
Rob Herring <robh@...nel.org>, Joe Perches <joe@...ches.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
linux-pci@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linuxarm <linuxarm@...wei.com>, Corey Minyard <minyard@....org>,
devicetree <devicetree@...r.kernel.org>,
Linux-Arch <linux-arch@...r.kernel.org>,
Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v13 7/9] ACPI: Translate the I/O range of non-MMIO devices
before scanning
On Tue, Feb 13, 2018 at 7:45 PM, John Garry <john.garry@...wei.com> 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.
>
> 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.
> + unsigned long sys_port;
> + sys_port = logic_pio_trans_hwaddr(&host->fwnode, res->start, len);
> + if (sys_port == -1UL)
Wouldn't it be better to compare with ULONG_MAX?
> + return -EFAULT;
> +/*
Shouldn't be a kernel-doc?
> + * acpi_indirect_io_set_res - set the resources for a child device
> + * (MFD) of an "indirect IO" host.
In that case this would be one line w/o period at the end.
> + * @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);
> + 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);
It has similarities with acpi_create_platform_device().
I guess we can utilize existing code.
> + /* 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;
Perhaps,
ret = ...
if (ret)
break;
}
if (ret) {
kfree(resources);
dev_err(child, "translate IO range failed(%d)\n", ret);
return ret;
}
*res = resources;
*num_res = count;
return 0;
?
> +}
> +
> +/*
> + * 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];
Plain x is equivalent to &x[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));
Casting to void * is pointless. In both cases.
> + 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);
So, NULL case will return 0. Is it expected?
> + 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;
> +}
One question, what a scope of use of this function? Is it ->probe() time?
If it's so, can we use devm_* variants?
--
With Best Regards,
Andy Shevchenko
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