linux-kernel - Re: [PATCH v5 04/10] reset: Add Sunplus SP7021 reset driver

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Message-ID: <75d34242693a41978fb7c6703dac3fd3a6437172.camel@pengutronix.de>
Date:   Tue, 07 Dec 2021 09:35:30 +0100
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Qin Jian <qinjian@...lus1.com>, robh+dt@...nel.org
Cc:     mturquette@...libre.com, sboyd@...nel.org, tglx@...utronix.de,
        maz@...nel.org, linux@...linux.org.uk, broonie@...nel.org,
        arnd@...db.de, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, wells.lu@...plus.com
Subject: Re: [PATCH v5 04/10] reset: Add Sunplus SP7021 reset driver

On Fri, 2021-12-03 at 15:34 +0800, Qin Jian wrote:
[...]
> diff --git a/drivers/reset/reset-sunplus.c b/drivers/reset/reset-sunplus.c
> new file mode 100644
> index 000000000..a1d88dbaf
> --- /dev/null
> +++ b/drivers/reset/reset-sunplus.c
> @@ -0,0 +1,132 @@
> +// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +/*
> + * SP7021 reset driver
> + *
> + * Copyright (C) Sunplus Technology Co., Ltd.
> + *       All rights reserved.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +#include <linux/reboot.h>
> +
> +/* HIWORD_MASK_REG BITS */
> +#define BITS_PER_HWM_REG	16
> +
> +struct sp_reset_data {
> +	struct reset_controller_dev rcdev;
> +	void __iomem *membase;
> +} *sp_reset;
     ^^^^^^^^^^

I'd prefer if you removed the global sp_reset pointer.

[...]
> +static int sp_restart(struct notifier_block *this, unsigned long mode,
> +		      void *cmd)
> +{

You could embed the sp_restart_nb notifier block in struct sp_reset_data
and use container_of(this, struct sp_reset_data, notifier) to get to the
rcdev here.

> +	sp_reset_assert(&sp_reset->rcdev, 0);
> +	sp_reset_deassert(&sp_reset->rcdev, 0);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static struct notifier_block sp_restart_nb = {
> +	.notifier_call = sp_restart,
> +	.priority = 192,
> +};
> +
> +static const struct reset_control_ops sp_reset_ops = {
> +	.assert   = sp_reset_assert,
> +	.deassert = sp_reset_deassert,
> +	.status   = sp_reset_status,
> +};
> +
> +static const struct of_device_id sp_reset_dt_ids[] = {
> +	{.compatible = "sunplus,sp7021-reset",},
> +	{ /* sentinel */ },
> +};
> +
> +static int sp_reset_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	void __iomem *membase;
> +	struct resource *res;
> +
> +	sp_reset = devm_kzalloc(&pdev->dev, sizeof(*sp_reset), GFP_KERNEL);
> +	if (!sp_reset)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	membase = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(membase))
> +		return PTR_ERR(membase);
> +
> +	sp_reset->membase = membase;
> +	sp_reset->rcdev.owner = THIS_MODULE;
> +	sp_reset->rcdev.nr_resets = resource_size(res) / 4 * 16;	/* HIWORD_MASK */
> +	sp_reset->rcdev.ops = &sp_reset_ops;
> +	sp_reset->rcdev.of_node = dev->of_node;
> +	register_restart_handler(&sp_restart_nb);

Either do this after devm_reset_controller_register(), which could
theoretically fail with -ENOMEM, or call unregister_restart_handler() in
the error case below.

> +
> +	return devm_reset_controller_register(dev, &sp_reset->rcdev);
> +}
> +
> +static struct platform_driver sp_reset_driver = {
> +	.probe = sp_reset_probe,
> +	.driver = {
> +		   .name = "sunplus-reset",
> +		   .of_match_table = sp_reset_dt_ids,
		^
Please fix the indentation, two tabs here.

		.suppress_bind_attrs = true,

to stop unbinding the driver. Alternatively, add a driver remove
function that unregisters the restart handler.

> +		   },
	^
One tab here.

> +};
> +
> +module_platform_driver(sp_reset_driver);
> +
> +MODULE_AUTHOR("Edwin Chiu <edwin.chiu@...plus.com>");
> +MODULE_DESCRIPTION("Sunplus Reset Driver");
> +MODULE_LICENSE("GPL v2");

regards
Philipp