linux-kernel - Re: [RFC PATCH 2/2] HISI LPC: Add PNP device support

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Date:   Fri, 20 Apr 2018 16:12:29 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     John Garry <john.garry@...wei.com>
Cc:     rjw@...ysocki.net, andriy.shevchenko@...ux.intel.com,
        linux-acpi@...r.kernel.org, lenb@...nel.org,
        lorenzo.pieralisi@....com, linux-kernel@...r.kernel.org,
        arnd@...db.de, graeme.gregory@...aro.org, helgaas@...nel.org,
        linuxarm@...wei.com, z.liuxinliang@...ilicon.com
Subject: Re: [RFC PATCH 2/2] HISI LPC: Add PNP device support

On Fri, Apr 20, 2018 at 06:07:26PM +0800, John Garry wrote:
> Currently the driver creates an per-ACPI device mfd_cell
> for child devices. This does not suit devices which are
> PNP-compatible, as we expect PNP-compatible devices to
> derive PNP devices.
> 
> To add PNP device support, we continue to allow the PNP
> scan code to create the PNP device (which have the
> enumeration_by_parent flag set), but expect the PNP
> scan to defer adding the device to allow the host probe
> code to do this. In addition, no longer do we create an
> mfd_cell (platform_device) for PNP-compatible devices.
> 
> We take this approach so that host probe code can
> translate the IO resources of the PNP device prior
> to adding the device.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>  drivers/bus/hisi_lpc.c | 38 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/hisi_lpc.c b/drivers/bus/hisi_lpc.c
> index 2d4611e..d228bc5 100644
> --- a/drivers/bus/hisi_lpc.c
> +++ b/drivers/bus/hisi_lpc.c
> @@ -17,8 +17,11 @@
>  #include <linux/of_address.h>
>  #include <linux/of_platform.h>
>  #include <linux/pci.h>
> +#include <linux/pnp.h>
>  #include <linux/slab.h>
>  
> +#include "../pnp/base.h"
> +
>  #define DRV_NAME "hisi-lpc"
>  
>  /*
> @@ -469,8 +472,11 @@ static int hisi_lpc_acpi_probe(struct device *hostdev)
>  	struct acpi_device *child;
>  	int size, ret, count = 0, cell_num = 0;
>  
> -	list_for_each_entry(child, &adev->children, node)
> +	list_for_each_entry(child, &adev->children, node) {
> +		if (acpi_is_pnp_device(child))
> +			continue;
>  		cell_num++;
> +	}
>  
>  	/* allocate the mfd cell and companion ACPI info, one per child */
>  	size = sizeof(*mfd_cells) + sizeof(*hisi_lpc_mfd_cells);
> @@ -492,6 +498,9 @@ static int hisi_lpc_acpi_probe(struct device *hostdev)
>  			.pnpid = pnpid,
>  		};
>  
> +		if (acpi_is_pnp_device(child))
> +			continue;
> +
>  		/*
>  		 * For any instances of this host controller (Hip06 and Hip07
>  		 * are the only chipsets), we would not have multiple slaves
> @@ -523,6 +532,33 @@ static int hisi_lpc_acpi_probe(struct device *hostdev)
>  		return ret;
>  	}
>  
> +	list_for_each_entry(child, &adev->children, node) {
> +		struct pnp_resource *pnp_res;
> +		struct pnp_dev *pnp_dev;
> +		int rc;
> +
> +		if (!acpi_is_pnp_device(child))
> +			continue;
> +
> +		pnp_dev = child->driver_data;

...or better yet a PNP helper function that makes this more
understandable.

> +
> +		/*
> +		 * Prior to adding the device, we need to translate the
> +		 * resources to logical PIO addresses.
> +		 */
> +		list_for_each_entry(pnp_res, &pnp_dev->resources, list) {
> +			struct resource *res = &pnp_res->res;
> +
> +			if (res->flags | IORESOURCE_IO)

I think you should use

	if (resource_type(res) == IORESOURCE_IO)

instead.

> +				hisi_lpc_acpi_xlat_io_res(child, adev, res);
> +		}
> +		rc = pnp_add_device(pnp_dev);
> +		if (rc) {
> +			put_device(&pnp_dev->dev);
> +			return rc;
> +		}
> +	}
> +
>  	return 0;
>  }
>  
> -- 
> 1.9.1