linux-kernel - Re: [PATCH v2 2/3] tpm_tis: Use devm_ioremap

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Message-ID: <20151201192240.GE5072@pengutronix.de>
Date:	Tue, 1 Dec 2015 20:22:40 +0100
From:	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:	Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
	tpmdd-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	Martin Wilck <Martin.Wilck@...fujitsu.com>,
	Peter Huewe <peterhuewe@....de>
Subject: Re: [PATCH v2 2/3] tpm_tis: Use devm_ioremap_resource

Hello,

On Tue, Dec 01, 2015 at 11:58:28AM -0700, Jason Gunthorpe wrote:
> This does a request_resource under the covers which means tis holds a
> lock on the memory range it is using so other drivers cannot grab it.
> When doing probing it is important to ensure that other drivers are
> not using the same range before tis starts touching it.
> 
> To do this flow the actual struct resource from the device right
> through to devm_ioremap_resource. This ensures all the proper resource
> meta-data is carried down.
> 
> Signed-off-by: Jason Gunthorpe <jgunthorpe@...idianresearch.com>
> ---
>  drivers/char/tpm/tpm_tis.c | 29 +++++++++++++++++------------
>  1 file changed, 17 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
> index 0a2d94f3d679..1032855c46b2 100644
> --- a/drivers/char/tpm/tpm_tis.c
> +++ b/drivers/char/tpm/tpm_tis.c
> @@ -67,14 +67,16 @@ enum tis_defaults {
>  };
>  
>  struct tpm_info {
> -	unsigned long start;
> -	unsigned long len;
> +	struct resource res;
>  	int irq;
>  };
>  
>  static struct tpm_info tis_default_info = {
> -	.start = TIS_MEM_BASE,
> -	.len = TIS_MEM_LEN,
> +	.res = {
> +		.start = TIS_MEM_BASE,
> +		.end = TIS_MEM_BASE + TIS_MEM_LEN - 1,
> +		.flags = IORESOURCE_MEM,
> +	},
>  	.irq = 0,
>  };
>  
> @@ -716,7 +718,7 @@ static int tpm_tis_init(struct device *dev, struct tpm_info *tpm_info,
>  	chip->acpi_dev_handle = acpi_dev_handle;
>  #endif
>  
> -	chip->vendor.iobase = devm_ioremap(dev, tpm_info->start, tpm_info->len);
> +	chip->vendor.iobase = devm_ioremap_resource(dev, &tpm_info->res);
>  	if (!chip->vendor.iobase)
>  		return -EIO;
>  
> @@ -899,9 +901,12 @@ static int tpm_tis_pnp_init(struct pnp_dev *pnp_dev,
>  {
>  	struct tpm_info tpm_info = {};
>  	acpi_handle acpi_dev_handle = NULL;
> +	struct resource *res;
>  
> -	tpm_info.start = pnp_mem_start(pnp_dev, 0);
> -	tpm_info.len = pnp_mem_len(pnp_dev, 0);
> +	res = pnp_get_resource(pnp_dev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENODEV;
> +	memcpy(&tpm_info.res, res, sizeof(*res));

I think you can do

	tpm_info.res = res;

here, which IMHO reads nicer and maybe is even more efficient (I don't
know much about x86).

>  	if (pnp_irq_valid(pnp_dev, 0))
>  		tpm_info.irq = pnp_irq(pnp_dev, 0);
> @@ -964,12 +969,9 @@ static int tpm_check_resource(struct acpi_resource *ares, void *data)
>  	struct tpm_info *tpm_info = (struct tpm_info *) data;
>  	struct resource res;
>  
> -	if (acpi_dev_resource_interrupt(ares, 0, &res)) {
> +	if (acpi_dev_resource_interrupt(ares, 0, &res))
>  		tpm_info->irq = res.start;
> -	} else if (acpi_dev_resource_memory(ares, &res)) {
> -		tpm_info->start = res.start;
> -		tpm_info->len = resource_size(&res);
> -	}
> +	acpi_dev_resource_memory(ares, &tpm_info->res);
>  
>  	return 1;
>  }
> @@ -992,6 +994,9 @@ static int tpm_tis_acpi_init(struct acpi_device *acpi_dev)
>  
>  	acpi_dev_free_resource_list(&resources);
>  
> +	if (resource_size(&tpm_info.res) == 0)
> +		return -ENODEV;
> +

Does this result in an error message from the upper layers?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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