lkml.org 
[lkml]   [2016]   [May]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v8 2/3] gpio: mmio: add DT support for memory-mapped GPIOs
From
Hi Christian,

On 8 May 2016 at 15:08, Christian Lamparter <chunkeey@googlemail.com> wrote:
> From: Álvaro Fernández Rojas <noltari@gmail.com>
>
> This patch adds support for defining memory-mapped GPIOs which
> are compatible with the existing gpio-mmio interface. The generic
> library provides support for many memory-mapped GPIO controllers
> that are found in various on-board FPGA and ASIC solutions that
> are used to control board's switches, LEDs, chip-selects,
> Ethernet/USB PHY power, etc.
>
> For setting GPIO's there are three configurations:
> 1. single input/output register resource (named "dat"),
> 2. set/clear pair (named "set" and "clr"),
> 3. single output register resource and single input resource
> ("set" and dat").
>
> The configuration is detected by which resources are present.
> For the single output register, this drives a 1 by setting a bit
> and a zero by clearing a bit. For the set clr pair, this drives
> a 1 by setting a bit in the set register and clears it by setting
> a bit in the clear register. The configuration is detected by
> which resources are present.
>
> For setting the GPIO direction, there are three configurations:
> a. simple bidirectional GPIOs that requires no configuration.
> b. an output direction register (named "dirout")
> where a 1 bit indicates the GPIO is an output.
> c. an input direction register (named "dirin")
> where a 1 bit indicates the GPIO is an input.
>
> The first user for this binding is "wd,mbl-gpio".
>
> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
> Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
> ---

> +#define ADD(_name, _func) { .compatible = _name, .data = _func }

I don't see the point in having a macro for such a simple data
structure, but since this v8 and Linus hasn't complained I guess it's
fine.

Using a macro here makes it impossible to grep for 'compatible'. Doing
'git grep compatible drivers/gpio/' is sometimes very useful to see
which hardware the driver actually supports.

> +static const struct of_device_id bgpio_of_match[] = {
> + ADD("wd,mbl-gpio", bgpio_basic_mmio_parse_dt),
> + { }
> +};
> +#undef ADD
> +MODULE_DEVICE_TABLE(of, bgpio_of_match);
> +
> +static struct bgpio_pdata *bgpio_parse_dt(struct platform_device *pdev,
> + unsigned long *flags)
> +{
> + const int (*parse_dt)(struct platform_device *,
> + struct bgpio_pdata *, unsigned long *);
> + const struct device_node *node = pdev->dev.of_node;
> + const struct of_device_id *of_id;
> + struct bgpio_pdata *pdata;
> + int err = -ENODEV;
> +
> + of_id = of_match_node(bgpio_of_match, node);
> + if (!of_id)
> + return NULL;
> +
> + pdata = devm_kzalloc(&pdev->dev, sizeof(struct bgpio_pdata),
> + GFP_KERNEL);
> + if (!pdata)
> + return ERR_PTR(-ENOMEM);
> +
> + parse_dt = (const void *)of_id->data;

You can retrieve OF match data using of_device_get_match_data(). Saves
you a couple of lines and better explains what your doing.


> + if (parse_dt)
> + err = parse_dt(pdev, pdata, flags);
> + if (err)
> + return ERR_PTR(err);
> +
> + return pdata;
> +}


regards,
Joachim Eastwood

\
 
 \ /
  Last update: 2016-05-08 19:41    [W:0.871 / U:1.852 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site