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SubjectRe: [PATCH v5 2/2] ACPI: amba bus probing support
From
On Mon, Jan 11, 2016 at 3:26 PM, Aleksey Makarov
<aleksey.makarov@linaro.org> wrote:
> From: Graeme Gregory <graeme.gregory@linaro.org>
>
> 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.
>

My comments below.

> +++ b/drivers/acpi/acpi_amba.c
> @@ -0,0 +1,122 @@
> +
> +/*
> + * ACPI support for platform bus type.
> + *
> + * Copyright (C) 2015, Linaro Ltd
> + * Author: Graeme Gregory <graeme.gregory@linaro.org>
> + *
> + * 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[] = {
> + {"ARMH0061", 0}, /* PL061 GPIO Device */
> + {"", 0},
> +};
> +
> +static void amba_register_dummy_clk(void)
> +{
> + static struct clk *amba_dummy_clk;
> +
> + /* If clock already registered */
> + if (amba_dummy_clk)
> + return;
> +
> + amba_dummy_clk = clk_register_fixed_rate(NULL, "apb_pclk", NULL,
> + CLK_IS_ROOT, 0);
> + clk_register_clkdev(amba_dummy_clk, "apb_pclk", NULL);
> +}
> +
> +static int amba_handler_attach(struct acpi_device *adev,
> + const struct acpi_device_id *id)
> +{
> + struct amba_device *dev;
> + struct resource_entry *rentry;
> + struct list_head resource_list;
> + bool address_found = false;
> + int irq_no = 0;
> + int ret;
> +
> + /* If the ACPI node already has a physical device attached, skip it. */
> + if (adev->physical_node_count)
> + return 0;
> +
> + dev = amba_device_alloc(dev_name(&adev->dev), 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;

dev->res is 0 before this one, right? Could you use this fact instead
of address_found flag?

> + 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");

Why? Isn't possible to have other resources for the devices?

> + break;
> + }
> + }
> +
> + 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 amba device we are about to create.
> + */
> + if (adev->parent)
> + dev->dev.parent = acpi_get_first_physical_node(adev->parent);
> +
> + ACPI_COMPANION_SET(&dev->dev, adev);
> +
> + ret = amba_device_add(dev, &iomem_resource);
> + if (ret) {

ret < 0?

What to do if ret > 0? It will be considered as not error. Please,
check what function returns and adjust this.

> + dev_err(&adev->dev, "%s(): amba_device_add() failed (%d)\n",
> + __func__, ret);
> + goto err_free;
> + }
> +
> + return 1;
> +
> +err_free:
> + amba_device_put(dev);
> + return ret;
> +}


--
With Best Regards,
Andy Shevchenko

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