Re: [PATCH v4 1/3] ACPI: amba bus probing support

[Andy Shevchenko]

On Wed, Dec 23, 2015 at 4:19 PM, Aleksey Makarov
<aleksey.makarov@xxxxxxxxxx> wrote:
> From: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
>
> On ARM64 some devices use the AMBA device and not the platform bus for
> probing so add support for this. Uses a dummy clock for apb_pclk as ACPI
> does not have a suitable clock representation and to keep the core
> AMBA bus code unchanged between probing methods.
>
> Signed-off-by: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
> Signed-off-by: Aleksey Makarov <aleksey.makarov@xxxxxxxxxx>
> ---
>  drivers/acpi/Makefile    |   1 +
>  drivers/acpi/acpi_amba.c | 140 +++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/acpi/internal.h  |   5 ++
>  3 files changed, 146 insertions(+)
>  create mode 100644 drivers/acpi/acpi_amba.c
>
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 675eaf3..3cf732f 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -43,6 +43,7 @@ acpi-y                                += pci_root.o pci_link.o pci_irq.o
>  acpi-y                         += acpi_lpss.o acpi_apd.o
>  acpi-y                         += acpi_platform.o
>  acpi-y                         += acpi_pnp.o
> +acpi-$(CONFIG_ARM_AMBA)        += acpi_amba.o
>  acpi-y                         += int340x_thermal.o
>  acpi-y                         += power.o
>  acpi-y                         += event.o
> diff --git a/drivers/acpi/acpi_amba.c b/drivers/acpi/acpi_amba.c
> new file mode 100644
> index 0000000..4b77d47
> --- /dev/null
> +++ b/drivers/acpi/acpi_amba.c
> @@ -0,0 +1,140 @@
> +
> +/*
> + * ACPI support for platform bus type.
> + *
> + * Copyright (C) 2015, Linaro Ltd
> + * Authors: Graeme Gregory <graeme.gregory@xxxxxxxxxx>

Plural form implies more then one author which makes sense after what
you did to the code.

> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/amba/bus.h>
> +#include <linux/clkdev.h>
> +#include <linux/clk-provider.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/ioport.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
> +#include "internal.h"
> +
> +static const struct acpi_device_id amba_id_list[] = {
> +       {"ARMH0011", 0}, /* PL011 SBSA Uart */
> +       {"ARMH0061", 0}, /* PL061 GPIO Device */
> +       {"", 0},
> +};
> +
> +static struct clk *amba_dummy_clk;

You may move this into the function, it will be still global, but
hidden from the namespace.

> +
> +static void amba_register_dummy_clk(void)
> +{
> +       struct clk *clk;
> +
> +       /* If clock already registered */
> +       if (amba_dummy_clk)
> +               return;
> +
> +       clk = clk_register_fixed_rate(NULL, "apb_pclk", NULL, CLK_IS_ROOT, 0);
> +       clk_register_clkdev(clk, "apb_pclk", NULL);
> +
> +       amba_dummy_clk = clk;
> +}
> +
> +static int amba_handler_attach(struct acpi_device *adev,
> +                               const struct acpi_device_id *id)
> +{
> +       struct amba_device *dev = NULL;

Redundant assignment.

> +       struct acpi_device *acpi_parent;
> +       struct resource_entry *rentry;
> +       struct list_head resource_list;
> +       bool address_found = false;
> +       int ret, irq_no = 0;

Better to split, they are not about the same by meaning.

> +
> +       /* If the ACPI node already has a physical device attached, skip it. */
> +       if (adev->physical_node_count)
> +               return 0;
> +
> +       dev = amba_device_alloc(NULL, 0, 0);
> +       if (!dev) {
> +               dev_err(&adev->dev, "%s(): amba_device_alloc() failed\n",
> +                       __func__);
> +               return -ENOMEM;
> +       }
> +
> +       INIT_LIST_HEAD(&resource_list);
> +       ret = acpi_dev_get_resources(adev, &resource_list, NULL, NULL);
> +       if (ret < 0)
> +               goto err_free;
> +
> +       list_for_each_entry(rentry, &resource_list, node) {
> +               switch (resource_type(rentry->res)) {
> +               case IORESOURCE_MEM:
> +                       if (!address_found) {
> +                               dev->res = *rentry->res;
> +                               address_found = true;
> +                       }
> +                       break;
> +               case IORESOURCE_IRQ:
> +                       if (irq_no < AMBA_NR_IRQS)
> +                               dev->irq[irq_no++] = rentry->res->start;
> +                       break;
> +               default:
> +                       dev_warn(&adev->dev, "Invalid resource\n");

Better to use break here as well.

> +               }
> +       }
> +
> +       acpi_dev_free_resource_list(&resource_list);
> +
> +       /*
> +        * If the ACPI node has a parent and that parent has a physical device
> +        * attached to it, that physical device should be the parent of the
> +        * platform device we are about to create.
> +        */
> +       dev->dev.parent = NULL;
> +       acpi_parent = adev->parent;
> +       if (acpi_parent) {
> +               struct acpi_device_physical_node *entry;
> +               struct list_head *list;
> +
> +               mutex_lock(&acpi_parent->physical_node_lock);
> +               list = &acpi_parent->physical_node_list;
> +               if (!list_empty(list)) {
> +                       entry = list_first_entry(list,
> +                                       struct acpi_device_physical_node,
> +                                       node);

There are couple of users already of the similar.
I would suggest for now to create local helper which we might easily
to move to one of drivers/acpi/ header.

static inline struct acpi_device_physical_node
*to_physical_node(struct acpi_dev *adev)
{
  if (list_empty(adev->physical_node_list))
    return NULL;
  return list_first_entry(adev->physical_node_list, struct
acpi_device_physical_node, node);
}

Rafael, what do you think?

> +                       dev->dev.parent = entry->dev;
> +               }
> +               mutex_unlock(&acpi_parent->physical_node_lock);
> +       }
> +
> +       dev_set_name(&dev->dev, "%s", dev_name(&adev->dev));
> +       ACPI_COMPANION_SET(&dev->dev, adev);
> +
> +       ret = amba_device_add(dev, &iomem_resource);
> +       if (ret) {
> +               dev_err(&adev->dev, "%s(): amba_device_add() failed (%d)\n",
> +                      __func__, ret);
> +               goto err_free;
> +       }
> +

Might be worth to comment out what 1 means here.

> +       return 1;
> +
> +err_free:
> +       amba_device_put(dev);
> +       return ret;
> +}
> +
> +static struct acpi_scan_handler amba_handler = {
> +       .ids = amba_id_list,
> +       .attach = amba_handler_attach,
> +};
> +
> +void __init acpi_amba_init(void)
> +{
> +       amba_register_dummy_clk();
> +       acpi_scan_add_handler(&amba_handler);
> +}
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 11d87bf..9d58f0c 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -29,6 +29,11 @@ void acpi_processor_init(void);
>  void acpi_platform_init(void);
>  void acpi_pnp_init(void);

>  void acpi_int340x_thermal_init(void);

Hmmâ Looks like we need specific header where drivers can put their
stuff and share with other internal ACPI modules.

> +#ifdef CONFIG_ARM_AMBA
> +void acpi_amba_init(void);
> +#else
> +static inline void acpi_amba_init(void) {}
> +#endif

Same.

>  int acpi_sysfs_init(void);
>  void acpi_container_init(void);
>  void acpi_memory_hotplug_init(void);
> --
> 2.6.4
>



-- 
With Best Regards,
Andy Shevchenko
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