Re: [PATCH v13 7/9] ACPI: Translate the I/O range of non-MMIO devices before scanning

[John Garry]

> > Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
> > Signed-off-by: Zhichang Yuan <yuanzhichang@xxxxxxxxxxxxx>
> > Signed-off-by: Gabriele Paoloni <gabriele.paoloni@xxxxxxxxxx>

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@xxxxxxxxxx>
> > + * Author: Zhichang Yuan <yuanzhichang@xxxxxxxxxxxxx>
> > + * Author: John Garry <john.garry@xxxxxxxxxx>
> > + *
> > + * 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@xxxxxxxxx>
>
> for the generic ACPI changes.

Thanks,
John

> .