Re: [PATCH 2/2] reset: uniphier: add USB3 controller reset control

[Philipp Zabel]

Hi Kunihiko,

thank you for the patch. I just have a few small comments below:

On Fri, 2018-06-29 at 17:11 +0900, Kunihiko Hayashi wrote:
> Add reset lines for USB3 controller implemented in UniPhier SoCs.
> 
> This reuses only the reset operations in reset-simple, because
> the reset-simple doesn't handle any SoC-dependent clocks and resets.
> This reset lines is included in the USB3 glue layer, and it's necessary
> to enable clocks and deassert resets of the layer before using this
> reset lines.
> 
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
> ---
>  drivers/reset/Kconfig               |  10 ++
>  drivers/reset/Makefile              |   1 +
>  drivers/reset/reset-uniphier-usb3.c | 183 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 194 insertions(+)
>  create mode 100644 drivers/reset/reset-uniphier-usb3.c
> 
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index c0b292b..851c9c3 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -138,6 +138,16 @@ config RESET_UNIPHIER
>  	  Say Y if you want to control reset signals provided by System Control
>  	  block, Media I/O block, Peripheral Block.
>  
> +config RESET_UNIPHIER_USB3
> +	tristate "USB3 reset driver for UniPhier SoCs"
> +	depends on (ARCH_UNIPHIER || COMPILE_TEST) && OF
> +	default ARCH_UNIPHIER
> +	select RESET_SIMPLE
> +	help
> +	  Support for USB3 reset controllers on UniPhier SoCs.
> +	  Say Y if you want to control reset signals provided by
> +	  USB3 controller block.
> +
>  config RESET_ZYNQ
>  	bool "ZYNQ Reset Driver" if COMPILE_TEST
>  	default ARCH_ZYNQ
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index c1261dc..2638ac4 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -20,5 +20,6 @@ obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
>  obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
>  obj-$(CONFIG_RESET_TI_SYSCON) += reset-ti-syscon.o
>  obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
> +obj-$(CONFIG_RESET_UNIPHIER_USB3) += reset-uniphier-usb3.o
>  obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
>  
> diff --git a/drivers/reset/reset-uniphier-usb3.c b/drivers/reset/reset-uniphier-usb3.c
> new file mode 100644
> index 0000000..397e6c9
> --- /dev/null
> +++ b/drivers/reset/reset-uniphier-usb3.c
> @@ -0,0 +1,183 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * reset-uniphier-usb3.c - USB3 reset driver for UniPhier
> + * Copyright 2018 Socionext Inc.
> + * Author: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset.h>
> +
> +#include "reset-simple.h"
> +
> +#define MAX_CLKS	2
> +#define MAX_RSTS	2
> +
> +struct uniphier_usb3_reset_soc_data {
> +	const char *clock_names[MAX_CLKS];
> +	const char *reset_names[MAX_RSTS];
> +};
> +
> +struct uniphier_usb3_reset_priv {

I'd embed a struct reset_simple_data here ...

> +	int nclks;
> +	struct clk *clk[MAX_CLKS];
> +	int nrsts;
> +	struct reset_control *rst[MAX_RSTS];
> +	const struct uniphier_usb3_reset_soc_data *data;
> +};
> +
> +static int uniphier_usb3_reset_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct uniphier_usb3_reset_priv *priv;
> +	struct reset_simple_data *rst_data;
> +	struct resource *res;
> +	resource_size_t size;
> +	const char *name;
> +	int i, ret, nc, nr;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->data = of_device_get_match_data(dev);
> +	if (WARN_ON(!priv->data))
> +		return -EINVAL;
> +
> +	rst_data = devm_kzalloc(dev, sizeof(*rst_data), GFP_KERNEL);
> +	if (!rst_data)
> +		return -ENOMEM;

... that way there's no need for two separate allocations.

> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	size = resource_size(res);
> +	rst_data->membase = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(rst_data->membase))
> +		return PTR_ERR(rst_data->membase);
> +
> +	for (i = 0; i < MAX_CLKS; i++) {
> +		name = priv->data->clock_names[i];
> +		if (!name)
> +			break;
> +		priv->clk[i] = devm_clk_get(dev, name);
> +		if (IS_ERR(priv->clk[i]))
> +			return PTR_ERR(priv->clk[i]);
> +		priv->nclks++;
> +	}
> +
> +	for (i = 0; i < MAX_RSTS; i++) {
> +		name = priv->data->reset_names[i];
> +		if (!name)
> +			break;
> +		priv->rst[i] = devm_reset_control_get_shared(dev, name);
> +		if (IS_ERR(priv->rst[i]))
> +			return PTR_ERR(priv->rst[i]);
> +		priv->nrsts++;
> +	}
> +
> +	for (nc = 0; nc < priv->nclks; nc++) {
> +		ret = clk_prepare_enable(priv->clk[nc]);
> +		if (ret)
> +			goto out_clk_disable;
> +	}
> +
> +	for (nr = 0; nr < priv->nrsts; nr++) {
> +		ret = reset_control_deassert(priv->rst[nr]);
> +		if (ret)
> +			goto out_rst_assert;
> +	}

Have you seen the clk_bulk_* APIs? Those could possibly simplify the
code a bit.
Unfortunately we don't have the equivalent reset bulk API.

> +
> +	spin_lock_init(&rst_data->lock);
> +	rst_data->rcdev.owner = THIS_MODULE;
> +	rst_data->rcdev.nr_resets = size * BITS_PER_BYTE;
> +	rst_data->rcdev.ops = &reset_simple_ops;
> +	rst_data->rcdev.of_node = dev->of_node;
> +	rst_data->active_low = true;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	ret = devm_reset_controller_register(dev, &rst_data->rcdev);
> +	if (ret)
> +		goto out_rst_assert;
> +
> +	return 0;
> +
> +out_rst_assert:
> +	while (nr--)
> +		reset_control_assert(priv->rst[nr]);
> +out_clk_disable:
> +	while (nc--)
> +		clk_disable_unprepare(priv->clk[nc]);
> +
> +	return ret;
> +}
> +
> +static int uniphier_usb3_reset_remove(struct platform_device *pdev)
> +{
> +	struct uniphier_usb3_reset_priv *priv = platform_get_drvdata(pdev);
> +	int i;
> +
> +	for (i = 0; i < priv->nrsts; i++)
> +		reset_control_assert(priv->rst[i]);
> +	for (i = 0; i < priv->nclks; i++)
> +		clk_disable_unprepare(priv->clk[i]);
> +
> +	return 0;
> +}
> +
> +static const struct uniphier_usb3_reset_soc_data uniphier_pro4_data = {
> +	.clock_names = { "gio", "link", },
> +	.reset_names = { "gio", "link", },
> +};
> +
> +static const struct uniphier_usb3_reset_soc_data uniphier_pxs2_data = {
> +	.clock_names = { "link", },
> +	.reset_names = { "link", },
> +};
> +
> +static const struct uniphier_usb3_reset_soc_data uniphier_ld20_data = {
> +	.clock_names = { "link", },
> +	.reset_names = { "link", },
> +};
> +
> +static const struct uniphier_usb3_reset_soc_data uniphier_pxs3_data = {
> +	.clock_names = { "link", },
> +	.reset_names = { "link", },
> +};

Could you reuse the same SoC data for pxs2, ld20 and pxs3?

> +static const struct of_device_id uniphier_usb3_reset_match[] = {
> +	{
> +		.compatible = "socionext,uniphier-pro4-usb3-reset",
> +		.data = &uniphier_pro4_data,
> +	},
> +	{
> +		.compatible = "socionext,uniphier-pxs2-usb3-reset",
> +		.data = &uniphier_pxs2_data,
> +	},
> +	{
> +		.compatible = "socionext,uniphier-ld20-usb3-reset",
> +		.data = &uniphier_ld20_data,
> +	},
> +	{
> +		.compatible = "socionext,uniphier-pxs3-usb3-reset",
> +		.data = &uniphier_pxs3_data,
> +	},
> +	{ /* Sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, uniphier_usb3_reset_match);
> +
> +static struct platform_driver uniphier_usb3_reset_driver = {
> +	.probe = uniphier_usb3_reset_probe,
> +	.remove = uniphier_usb3_reset_remove,
> +	.driver = {
> +		.name = "uniphier-usb3-reset",
> +		.of_match_table = uniphier_usb3_reset_match,
> +	},
> +};
> +module_platform_driver(uniphier_usb3_reset_driver);
> +
> +MODULE_AUTHOR("Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("UniPhier USB3 Reset Driver");
> +MODULE_LICENSE("GPL");

regards
Philipp