Re: [PATCH v2 3/3] reset: zx2967: add reset controller driver for ZTE's zx2967 family

[Philipp Zabel]

On Mon, 2017-01-16 at 22:28 +0800, Jun Nie wrote:
> On 2017å01æ16æ 18:56, Baoyou Xie wrote:
> > This patch adds reset controller driver for ZTE's zx2967 family.
> >
> > Signed-off-by: Baoyou Xie <baoyou.xie@xxxxxxxxxx>
> > ---
> >  drivers/reset/Kconfig        |   6 +++
> >  drivers/reset/Makefile       |   1 +
> >  drivers/reset/reset-zx2967.c | 125 +++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 132 insertions(+)
> >  create mode 100644 drivers/reset/reset-zx2967.c
> >
> > diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> > index 172dc96..f4cdfe9 100644
> > --- a/drivers/reset/Kconfig
> > +++ b/drivers/reset/Kconfig
> > @@ -86,6 +86,12 @@ 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_ZX2967
> > +	bool "ZTE ZX2967 Reset Driver"
> > +	depends on ARCH_ZX || COMPILE_TEST
> > +	help
> > +	  This enables the reset controller driver for ZTE's zx2967 family.
> > +
> >  config RESET_ZYNQ
> >  	bool "ZYNQ Reset Driver" if COMPILE_TEST
> >  	default ARCH_ZYNQ
> > diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> > index 13b346e..2cd3f6c 100644
> > --- a/drivers/reset/Makefile
> > +++ b/drivers/reset/Makefile
> > @@ -13,4 +13,5 @@ obj-$(CONFIG_RESET_STM32) += reset-stm32.o
> >  obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
> >  obj-$(CONFIG_TI_SYSCON_RESET) += reset-ti-syscon.o
> >  obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
> > +obj-$(CONFIG_RESET_ZX2967) += reset-zx2967.o
> >  obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
> > diff --git a/drivers/reset/reset-zx2967.c b/drivers/reset/reset-zx2967.c
> > new file mode 100644
> > index 0000000..bc95261
> > --- /dev/null
> > +++ b/drivers/reset/reset-zx2967.c
> > @@ -0,0 +1,125 @@
> > +/*
> > + * ZTE's zx2967 family reset controller driver
> > + *
> > + * Copyright (C) 2017 ZTE Ltd.
> > + *
> > + * Author: Baoyou Xie <baoyou.xie@xxxxxxxxxx>
> > + *
> > + * License terms: GNU General Public License (GPL) version 2
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/reset-controller.h>
> > +
> > +struct zx2967_reset {
> > +	void __iomem			*reg_base;
> > +	spinlock_t			lock;
> > +	struct reset_controller_dev	rcdev;
> > +};
> > +
> > +static int zx2967_reset_act(struct reset_controller_dev *rcdev,
> > +			    unsigned long id, bool assert)
> > +{
> > +	struct zx2967_reset *reset = NULL;
> > +	u32 bank = id / 32;
> > +	u32 offset = id % 32;

Not terribly important, but int for bank and offset was just fine.

> > +	u32 reg;
> > +	unsigned long flags;
> > +
> > +	reset = container_of(rcdev, struct zx2967_reset, rcdev);
> > +
> > +	spin_lock_irqsave(&reset->lock, flags);
> > +
> > +	reg = readl(reset->reg_base + (bank * 4));
> 
> readl_relaxed is recommended.
> 
> > +	if (assert)
> > +		reg &= ~BIT(offset);
> > +	else
> > +		reg |= BIT(offset);
> > +	writel(reg, reset->reg_base + (bank * 4));
> 
> writel_relaxed is recommended.

Why? Resets are usually not performance critical.

> > +
> > +	spin_unlock_irqrestore(&reset->lock, flags);
> > +
> > +	return 0;
> > +}
> > +
> > +static int zx2967_reset_assert(struct reset_controller_dev *rcdev,
> > +			       unsigned long id)
> > +{
> > +	return zx2967_reset_act(rcdev, id, true);
> > +}
> > +
> > +static int zx2967_reset_deassert(struct reset_controller_dev *rcdev,
> > +				 unsigned long id)
> > +{
> > +	return zx2967_reset_act(rcdev, id, false);
> > +}
> > +
> > +static struct reset_control_ops zx2967_reset_ops = {
> > +	.assert		= zx2967_reset_assert,
> > +	.deassert	= zx2967_reset_deassert,
> > +};
> > +
> > +static int zx2967_reset_probe(struct platform_device *pdev)
> > +{
> > +	struct zx2967_reset *reset;
> > +	struct resource *res;
> > +
> > +	reset = devm_kzalloc(&pdev->dev, sizeof(*reset), GFP_KERNEL);
> > +	if (!reset)
> > +		return -ENOMEM;
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	reset->reg_base = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(reset->reg_base))
> > +		return PTR_ERR(reset->reg_base);
> > +
> > +	spin_lock_init(&reset->lock);
> > +
> > +	reset->rcdev.owner = THIS_MODULE;
> > +	reset->rcdev.nr_resets = resource_size(res) * 8;
> > +	reset->rcdev.ops = &zx2967_reset_ops;
> > +	reset->rcdev.of_node = pdev->dev.of_node;
> > +
> > +	dev_info(&pdev->dev, "reset controller cnt:%d",
> > +		  reset->rcdev.nr_resets);

This is a bit noisy. Can we just drop it?

> > +	return devm_reset_controller_register(&pdev->dev, &reset->rcdev);
> > +}
> > +
> > +static int zx2967_reset_remove(struct platform_device *pdev)
> > +{
> > +	return 0;
> > +}

Remove this function.

> > +static const struct of_device_id zx2967_reset_dt_ids[] = {
> > +	 { .compatible = "zte,zx296718-reset", },
> > +	 {},
> > +};
> > +MODULE_DEVICE_TABLE(of, zx2967_reset_dt_ids);
> > +
> > +static struct platform_driver zx2967_reset_driver = {
> > +	.probe	= zx2967_reset_probe,
> > +	.remove	= zx2967_reset_remove,

Remove the above line.

> > +	.driver = {
> > +		.name		= "zx2967-reset",
> > +		.of_match_table	= zx2967_reset_dt_ids,
> > +	},
> > +};
> 
> This line can replace all below code if you do not have any other 
> dependency in earlier stage.
> 
> builtin_platform_driver(zx2967_reset_driver);
> 
> > +
> > +static int __init zx2967_reset_init(void)
> > +{
> > +	return platform_driver_register(&zx2967_reset_driver);
> > +}
> > +arch_initcall(zx2967_reset_init);
> > +
> > +static void __exit zx2967_reset_exit(void)
> > +{
> > +	platform_driver_unregister(&zx2967_reset_driver);
> > +}
> > +module_exit(zx2967_reset_exit);
> > +
> > +MODULE_AUTHOR("Baoyou Xie <baoyou.xie@xxxxxxxxxx>");
> > +MODULE_DESCRIPTION("ZTE zx2967 Reset Controller Driver");
> > +MODULE_LICENSE("GPL");
> >

regards
Philipp