Re: [PATCH 2/2] reset: Add basic single-register reset driver

[Andy Shevchenko]

On Fri, May 26, 2017 at 6:32 AM, Joel Stanley <joel@xxxxxxxxx> wrote:
> This driver is a basic single-register reset controller driver that
> supports clearing a single bit in a register.
>

While this makes sense, I'm wondering if there can be generic
interface for this from which we can derive this one and GPIO-based
one.

> Signed-off-by: Joel Stanley <joel@xxxxxxxxx>
> ---
>  drivers/reset/Kconfig       |   6 +++
>  drivers/reset/Makefile      |   1 +
>  drivers/reset/reset-basic.c | 109 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 116 insertions(+)
>  create mode 100644 drivers/reset/reset-basic.c
>
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index d21c07ccc94e..980cda887dfe 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -28,6 +28,12 @@ config RESET_ATH79
>           This enables the ATH79 reset controller driver that supports the
>           AR71xx SoC reset controller.
>
> +config RESET_BASIC
> +       bool "Basic Reset Driver"
> +       help
> +         This enables a basic single-register reset controller driver that
> +         supports clearing a single bit in a register.
> +
>  config RESET_BERLIN
>         bool "Berlin Reset Driver" if COMPILE_TEST
>         default ARCH_BERLIN
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 02a74db94339..e8e8869e098d 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -4,6 +4,7 @@ obj-$(CONFIG_ARCH_STI) += sti/
>  obj-$(CONFIG_ARCH_TEGRA) += tegra/
>  obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
>  obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
> +obj-$(CONFIG_RESET_BASIC) += reset-basic.o
>  obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
>  obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
> diff --git a/drivers/reset/reset-basic.c b/drivers/reset/reset-basic.c
> new file mode 100644
> index 000000000000..62a676de9f62
> --- /dev/null
> +++ b/drivers/reset/reset-basic.c
> @@ -0,0 +1,109 @@
> +/*
> + * Copyright 2017 IBM Corperation
> + *
> + * Joel Stanley <joel@xxxxxxxxx>
> + *
> + * 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/delay.h>
> +#include <linux/init.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/reset-controller.h>
> +
> +#define to_basic_reset_priv(p)         \
> +       container_of((p), struct basic_reset_priv, rcdev)
> +
> +struct basic_reset_priv {
> +       struct regmap *regmap;
> +       struct reset_controller_dev rcdev;
> +       u32 reg;
> +};
> +
> +static int basic_reset_assert(struct reset_controller_dev *rcdev,
> +                              unsigned long id)
> +{
> +       struct basic_reset_priv *priv = to_basic_reset_priv(rcdev);
> +       u32 mask = BIT(id);
> +
> +       regmap_update_bits(priv->regmap, priv->reg, mask, mask);
> +
> +       return 0;
> +}
> +
> +static int basic_reset_deassert(struct reset_controller_dev *rcdev,
> +                                unsigned long id)
> +{
> +       struct basic_reset_priv *priv = to_basic_reset_priv(rcdev);
> +       u32 mask = BIT(id);
> +
> +       regmap_update_bits(priv->regmap, priv->reg, mask, 0);
> +
> +       return 0;
> +}
> +
> +static int basic_reset_status(struct reset_controller_dev *rcdev,
> +                              unsigned long id)
> +{
> +       struct basic_reset_priv *priv = to_basic_reset_priv(rcdev);
> +       u32 mask = BIT(id);
> +       u32 val;
> +
> +       regmap_read(priv->regmap, priv->reg, &val);
> +
> +       return !!(val & mask);
> +}
> +
> +static const struct reset_control_ops basic_reset_ops = {
> +       .assert = basic_reset_assert,
> +       .deassert = basic_reset_deassert,
> +       .status = basic_reset_status,
> +};
> +
> +static int basic_reset_probe(struct platform_device *pdev)
> +{
> +       struct device_node *parent_np = of_get_parent(pdev->dev.of_node);
> +       struct basic_reset_priv *priv;
> +       int ret;
> +
> +       priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +       if (!priv)
> +               return -ENOMEM;
> +
> +       priv->regmap = syscon_node_to_regmap(parent_np);
> +       of_node_put(parent_np);
> +       if (IS_ERR(priv->regmap))
> +               return PTR_ERR(priv->regmap);
> +
> +       ret = of_property_read_u32(pdev->dev.of_node, "reg", &priv->reg);
> +       if (ret)
> +               return ret;
> +
> +       priv->rcdev.owner = THIS_MODULE;
> +       priv->rcdev.ops = &basic_reset_ops;
> +       priv->rcdev.of_node = pdev->dev.of_node;
> +       priv->rcdev.nr_resets = 32;
> +
> +       return reset_controller_register(&priv->rcdev);
> +}
> +
> +static const struct of_device_id basic_reset_dt_match[] = {
> +       { .compatible = "reset-basic" },
> +       { },
> +};
> +
> +static struct platform_driver basic_reset_driver = {
> +       .probe  = basic_reset_probe,
> +       .driver = {
> +               .name = "basic-reset",
> +               .of_match_table = basic_reset_dt_match,
> +       },
> +};
> +builtin_platform_driver(basic_reset_driver);
> --
> 2.11.0
>



-- 
With Best Regards,
Andy Shevchenko