[PATCH v2 1/3] ARM: meson: reset: Add reset controller for MesonX SoCs

[Philipp Zabel]

Hi Carlo,

On Tue, Oct 14, 2014 at 08:35:47PM +0200, Carlo Caione wrote:
> This patch adds support for the reset controller found on the Amlogic
> MesonX SoCs. For several devices in the AO (Always-On) power domain, it
> is possible to reset them by programming a specific bit in a register.
> 
> Signed-off-by: Carlo Caione <carlo at caione.org>
> ---
>  drivers/reset/Makefile      |   1 +
>  drivers/reset/reset-meson.c | 142 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 143 insertions(+)
>  create mode 100644 drivers/reset/reset-meson.c
> 
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 60fed3d..74f2372 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -1,4 +1,5 @@
>  obj-$(CONFIG_RESET_CONTROLLER) += core.o
>  obj-$(CONFIG_ARCH_SOCFPGA) += reset-socfpga.o
>  obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
> +obj-$(CONFIG_ARCH_MESON) += reset-meson.o
>  obj-$(CONFIG_ARCH_STI) += sti/
> diff --git a/drivers/reset/reset-meson.c b/drivers/reset/reset-meson.c
> new file mode 100644
> index 0000000..59b58e4
> --- /dev/null
> +++ b/drivers/reset/reset-meson.c
> @@ -0,0 +1,142 @@
> +/*
> + * Copyright 2014 Carlo Caione <carlo at caione.org>
> + *
> + * based on
> + * Steffen Trumtrar Reset Controller driver

That doesn't sound right. Do you mean socfpga-reset?

> + * Copyright 2014 Steffen Trumtrar
> + *
> + * Steffen Trumtrar <s.trumtrar at pengutronix.de>

Could be combined into a single line.

> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +#include <linux/spinlock.h>
> +#include <linux/types.h>
> +
> +#define MESON_RST_OFFSET	0x00

If there is only one register, I see no need for this.

> +struct meson_reset_data {
> +	spinlock_t			lock;
> +	void __iomem			*membase;
> +	struct reset_controller_dev	rcdev;
> +};
> +
> +static int meson_reset_assert(struct reset_controller_dev *rcdev,
> +			      unsigned long id)
> +{
> +	struct meson_reset_data *data = container_of(rcdev,
> +						     struct meson_reset_data,
> +						     rcdev);
> +	unsigned long flags;
> +	u32 reg;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +
> +	reg = readl(data->membase + MESON_RST_OFFSET);
> +	writel(reg | BIT(id), data->membase + MESON_RST_OFFSET);
> +
> +	spin_unlock_irqrestore(&data->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int meson_reset_deassert(struct reset_controller_dev *rcdev,
> +				unsigned long id)
> +{
> +	struct meson_reset_data *data = container_of(rcdev,
> +						     struct meson_reset_data,
> +						     rcdev);
> +
> +	unsigned long flags;
> +	u32 reg;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +
> +	reg = readl(data->membase + MESON_RST_OFFSET);
> +	writel(reg & ~BIT(id), data->membase + MESON_RST_OFFSET);
> +
> +	spin_unlock_irqrestore(&data->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int meson_reset_dev(struct reset_controller_dev *rcdev, unsigned long id)
> +{
> +	int err;
> +
> +	err = meson_reset_assert(rcdev, id);
> +	if (err)
> +		return err;
> +
> +	return meson_reset_deassert(rcdev, id);
> +}
> +
> +static struct reset_control_ops meson_reset_ops = {
> +	.assert		= meson_reset_assert,
> +	.deassert	= meson_reset_deassert,
> +	.reset		= meson_reset_dev,
> +};
> +
> +static int meson_reset_probe(struct platform_device *pdev)
> +{
> +	struct meson_reset_data *data;
> +	struct resource *res;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	data->membase = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(data->membase))
> +		return PTR_ERR(data->membase);
> +
> +	spin_lock_init(&data->lock);
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	data->rcdev.owner = THIS_MODULE;
> +	data->rcdev.nr_resets = BITS_PER_LONG;

Are all bits in this registers reset controls (or rather, are you
positive there is no bit in this register used by anything else)?

> +	data->rcdev.ops = &meson_reset_ops;
> +	data->rcdev.of_node = pdev->dev.of_node;
> +
> +	return reset_controller_register(&data->rcdev);
> +}
> +
> +static int meson_reset_remove(struct platform_device *pdev)
> +{
> +	struct meson_reset_data *data = platform_get_drvdata(pdev);
> +
> +	reset_controller_unregister(&data->rcdev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id meson_reset_dt_ids[] = {
> +	{ .compatible = "amlogic,meson6-rst-mgr-ao", },
> +	{ /* sentinel */ },
> +};
> +
> +static struct platform_driver meson_reset_driver = {
> +	.probe	= meson_reset_probe,
> +	.remove	= meson_reset_remove,
> +	.driver = {
> +		.name		= "meson-reset",
> +		.of_match_table	= meson_reset_dt_ids,
> +	},
> +};
> +module_platform_driver(meson_reset_driver);
> +
> +MODULE_AUTHOR("Carlo Caione <carlo at caione.org>");
> +MODULE_DESCRIPTION("Meson Reset Controller Driver");
> +MODULE_LICENSE("GPL");
> -- 
> 1.9.1

Other than that, the driver looks good.

regards
Philipp