Date:   Wed, 14 Feb 2018 12:48:58 +0000
From:   John Garry <john.garry@...wei.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        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>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Rob Herring <robh@...nel.org>, Joe Perches <joe@...ches.com>,
        "Benjamin Herrenschmidt" <benh@...nel.crashing.org>,
        Linux PCI <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@...r.kernel.org" <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


>> 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>
>

Hi Rafael,

Thanks for checking again.

> Just a few minor nits below.
>
>> ---
>>  drivers/acpi/arm64/Makefile          |   1 +
>>  drivers/acpi/arm64/acpi_indirectio.c | 250 +++++++++++++++++++++++++++++++++++
>>  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.
>
> The above should fit into a single line.
>
> I'd make it something like "acpi_indirect_io_set_res - set "indirect
> IO" host child (MFD) resources" and it already is explained in the
> comment below.

Fine

>
>> + * @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
>
> host-relative

right

>
>> + * 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");
>
> dev_dbg()?
>
>> +               return 0;
>> +       }
>> +       /* whether the child had been enumerated? */
>> +       if (acpi_device_enumerated(adev)) {
>> +               dev_info(child, "had been enumerated\n");
>
> Again, dev_dbg()?

sure, I think that these can be downgraded

>
>> +               return 0;
>> +       }
>> +
>> +       count = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
>> +       if (count <= 0) {
>> +               dev_err(child, "failed to get resources\n");
>
> I'd use dev_dbg() here too (the message may not even be meaningful to a user).

I think that it could be ok - having no resources is not really an "error".

>
>> +               return count ? count : -EIO;
>> +       }
>> +
>> +       resources = kcalloc(count, sizeof(*resources), GFP_KERNEL);
>> +       if (!resources) {
>
> And you don't print anything here, I wonder why?

As I see, we generally don't print out-of-memory failure as we expect 
the alloc code to do it.

But I agree it's useful as we know the point of failure in the driver 
and can add diagnostic info like count value, as maybe we're trying to 
allocate a huge amount of memory.

>
>> +               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
>
> One extra empty comment line here, please.

ok

>
>> + * 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);
>
> Again, please consider using dev_dbg() here and below (for the same
> reason as above).
>

well if this happens the device is not enumerated, so I think a warn may 
be more appropiate

>> +                       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");

as above

>> +               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;
>
> return 0;
>
> You know that ret must be 0 here anyway.

yes, I prefer this

>
>> +
>> +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;
>
> The above can be written as
>
> return ret < 0 ? ret : 1;
>
> to save a few lines of code (you are using this pattern above, so why
> not here?).

I can change it.

>
>> +}
>> +
>> +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);
>>
>> --
>
> But generally
>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> for the generic ACPI changes.
>

Thanks,
John

> .
>

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