linux-kernel - Re: [PATCH v2 01/12] reset: add the Berlin reset controller driver

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Message-ID: <1403608416.2910.15.camel@paszta.hi.pengutronix.de>
Date:	Tue, 24 Jun 2014 13:13:36 +0200
From:	Philipp Zabel <p.zabel@...gutronix.de>
To:	Antoine Ténart 
	<antoine.tenart@...e-electrons.com>
Cc:	sebastian.hesselbarth@...il.com,
	alexandre.belloni@...e-electrons.com,
	thomas.petazzoni@...e-electrons.com, zmxu@...vell.com,
	jszhang@...vell.com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/12] reset: add the Berlin reset controller driver

Hi Antoine,

Am Dienstag, den 24.06.2014, 12:35 +0200 schrieb Antoine Ténart:
[...]
> +++ b/drivers/reset/reset-berlin.c
> @@ -0,0 +1,131 @@
> +/*
> + * Copyright (C) 2014 Marvell Technology Group Ltd.
> + *
> + * Antoine Ténart <antoine.tenart@...e-electrons.com>
> + * Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +#define to_berlin_reset_priv(p)		\
> +	container_of((p), struct berlin_reset_priv, rcdev)
> +
> +struct berlin_reset_priv {
> +	spinlock_t			lock;

lock is not used anymore.

[...]
> +static int berlin_reset_xlate(struct reset_controller_dev *rcdev,
> +			      const struct of_phandle_args *reset_spec)
> +{
> +	struct berlin_reset_priv *priv = to_berlin_reset_priv(rcdev);
> +	unsigned offset, bit;
> +
> +	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
> +		return -EINVAL;
> +
> +	offset = reset_spec->args[0];
> +	bit = reset_spec->args[1];
> +
> +	if (offset >= priv->size)
> +		return -EINVAL;
> +
> +	if (bit >= rcdev->nr_resets)
> +		return -EINVAL;

This could be considered a misuse of nr_resets, even if the core only
ever uses nr_resets in the _xlate function. Maybe it would be more clear
to just leave nr_resets empty if you don't know the actual number and
hardcode 32 here.

[...]
> +static int __berlin_reset_init(struct device_node *np)
> +{
> +	struct berlin_reset_priv *priv;
> +	struct resource res;
> +	resource_size_t size;
> +	int ret;
> +
> +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	ret = of_address_to_resource(np, 0, &res);
> +	if (ret)
> +		goto err;
> +
> +	size = resource_size(&res);
> +	priv->base = ioremap(res.start, size);
> +	if (!priv->base) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +	priv->size = size;
> +
> +	priv->rcdev.owner = THIS_MODULE;
> +	priv->rcdev.nr_resets = 32;

Leave nr_resets empty, use the correct value, or at least add a comment
that this is not the number of resets in the rcdev as documented in the
structure documentation.

> +	priv->rcdev.ops = &berlin_reset_ops;
> +	priv->rcdev.of_node = np;
> +	priv->rcdev.of_reset_n_cells = 2;
> +	priv->rcdev.of_xlate = berlin_reset_xlate;
> +
> +	reset_controller_register(&priv->rcdev);
> +
> +	return 0;
> +
> +err:
> +	kfree(priv);
> +	return ret;
> +}
> +
> +static const struct of_device_id berlin_reset_of_match[] __initconst = {
> +	{ .compatible = "marvell,berlin2-chip-ctrl" },
> +	{ .compatible = "marvell,berlin2cd-chip-ctrl" },
> +	{ .compatible = "marvell,berlin2q-chip-ctrl" },
> +	{ },
> +};
> +
> +static int __init berlin_reset_init(void)
> +{
> +	struct device_node *np;
> +	int ret;
> +
> +	for_each_matching_node(np, berlin_reset_of_match) {
> +		ret = __berlin_reset_init(np);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +arch_initcall(berlin_reset_init);

Other than the above, and with the understanding that this is going to
be turned into a platform driver at some point in the future,

Acked-by: Philipp Zabel <p.zabel@...gutronix.de>

regards
Philipp

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