Re: [PATCH v10 10/16] reset: Add a reset controller driver for the Lantiq XWAY based SoCs

[Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>]

On Sun, Aug 20, 2017 at 12:18 AM, Hauke Mehrtens <hauke-5/S+JYg5SzeELgA04lAiVw@public.gmane.org> wrote:
> From: Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
>
> The reset controllers (on xRX200 and newer SoCs have two of them) are
> provided by the RCU module. This was initially implemented as a simple
> reset controller. However, the RCU module provides more functionality
> (ethernet GPHYs, USB PHY, etc.), which makes it a MFD device.
> The old reset controller driver implementation from
> arch/mips/lantiq/xway/reset.c did not honor this fact.
>
> For some devices the request and the status bits are different.
>
> Signed-off-by: Hauke Mehrtens <hauke-5/S+JYg5SzeELgA04lAiVw@public.gmane.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Acked-by: Philipp Zabel <p.zabel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>

thank you Hauke for pushing this!

> ---
>  .../devicetree/bindings/reset/lantiq,reset.txt     |  30 +++
>  drivers/reset/Kconfig                              |   6 +
>  drivers/reset/Makefile                             |   1 +
>  drivers/reset/reset-lantiq.c                       | 212 +++++++++++++++++++++
>  4 files changed, 249 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reset/lantiq,reset.txt
>  create mode 100644 drivers/reset/reset-lantiq.c
>
> diff --git a/Documentation/devicetree/bindings/reset/lantiq,reset.txt b/Documentation/devicetree/bindings/reset/lantiq,reset.txt
> new file mode 100644
> index 000000000000..c6aef36b7d15
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reset/lantiq,reset.txt
> @@ -0,0 +1,30 @@
> +Lantiq XWAY SoC RCU reset controller binding
> +============================================
> +
> +This binding describes a reset-controller found on the RCU module on Lantiq
> +XWAY SoCs.
> +
> +This node has to be a sub node of the Lantiq RCU block.
> +
> +-------------------------------------------------------------------------------
> +Required properties:
> +- compatible           : Should be one of
> +                               "lantiq,danube-reset"
> +                               "lantiq,xrx200-reset"
> +- reg                  : Defines the following sets of registers in the parent
> +                         syscon device
> +                       - Offset of the reset set register
> +                       - Offset of the reset status register
> +- #reset-cells         : Specifies the number of cells needed to encode the
> +                         reset line, should be 2.
> +                         The first cell takes the reset set bit and the
> +                         second cell takes the status bit.
> +
> +-------------------------------------------------------------------------------
> +Example for the reset-controllers on the xRX200 SoCs:
> +       reset0: reset-controller@10 {
> +               compatible = "lantiq,xrx200-reset";
> +               reg <0x10 0x04>, <0x14 0x04>;
> +
> +               #reset-cells = <2>;
> +       };
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index 608c071e4bbf..4172ea1827f8 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -48,6 +48,12 @@ config RESET_IMX7
>         help
>           This enables the reset controller driver for i.MX7 SoCs.
>
> +config RESET_LANTIQ
> +       bool "Lantiq XWAY Reset Driver" if COMPILE_TEST
> +       default SOC_TYPE_XWAY
> +       help
> +         This enables the reset controller driver for Lantiq / Intel XWAY SoCs.
> +
>  config RESET_LPC18XX
>         bool "LPC18xx/43xx Reset Driver" if COMPILE_TEST
>         default ARCH_LPC18XX
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 7081f9da2599..54d8b3f703f2 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -7,6 +7,7 @@ obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
>  obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
>  obj-$(CONFIG_RESET_GEMINI) += reset-gemini.o
>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
> +obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
>  obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
>  obj-$(CONFIG_RESET_MESON) += reset-meson.o
>  obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
> diff --git a/drivers/reset/reset-lantiq.c b/drivers/reset/reset-lantiq.c
> new file mode 100644
> index 000000000000..11a582e50d30
> --- /dev/null
> +++ b/drivers/reset/reset-lantiq.c
> @@ -0,0 +1,212 @@
> +/*
> + *  This program is free software; you can redistribute it and/or modify it
> + *  under the terms of the GNU General Public License version 2 as published
> + *  by the Free Software Foundation.
> + *
> + *  Copyright (C) 2010 John Crispin <blogic-Pj+rj9U5foFAfugRpC6u6w@public.gmane.org>
> + *  Copyright (C) 2013-2015 Lantiq Beteiligungs-GmbH & Co.KG
> + *  Copyright (C) 2016 Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
> + *  Copyright (C) 2017 Hauke Mehrtens <hauke-5/S+JYg5SzeELgA04lAiVw@public.gmane.org>
> + */
> +
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/reset-controller.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +
> +#define LANTIQ_RCU_RESET_TIMEOUT       10000
> +
> +struct lantiq_rcu_reset_priv {
> +       struct reset_controller_dev rcdev;
> +       struct device *dev;
> +       struct regmap *regmap;
> +       u32 reset_offset;
> +       u32 status_offset;
> +};
> +
> +static struct lantiq_rcu_reset_priv *to_lantiq_rcu_reset_priv(
> +       struct reset_controller_dev *rcdev)
> +{
> +       return container_of(rcdev, struct lantiq_rcu_reset_priv, rcdev);
> +}
> +
> +static int lantiq_rcu_reset_status(struct reset_controller_dev *rcdev,
> +                                  unsigned long id)
> +{
> +       struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
> +       unsigned int status = (id >> 8) & 0x1f;
> +       u32 val;
> +       int ret;
> +
> +       ret = regmap_read(priv->regmap, priv->status_offset, &val);
> +       if (ret)
> +               return ret;
> +
> +       return !!(val & BIT(status));
> +}
> +
> +static int lantiq_rcu_reset_status_timeout(struct reset_controller_dev *rcdev,
> +                                          unsigned long id, bool assert)
> +{
> +       int ret;
> +       int retry = LANTIQ_RCU_RESET_TIMEOUT;
> +
> +       do {
> +               ret = lantiq_rcu_reset_status(rcdev, id);
> +               if (ret < 0)
> +                       return ret;
> +               if (ret == assert)
> +                       return 0;
> +               usleep_range(20, 40);
> +       } while (--retry);
> +
> +       return -ETIMEDOUT;
> +}
> +
> +static int lantiq_rcu_reset_update(struct reset_controller_dev *rcdev,
> +                                  unsigned long id, bool assert)
> +{
> +       struct lantiq_rcu_reset_priv *priv = to_lantiq_rcu_reset_priv(rcdev);
> +       unsigned int set = id & 0x1f;
> +       u32 val = assert ? BIT(set) : 0;
> +       int ret;
> +
> +       ret = regmap_update_bits(priv->regmap, priv->reset_offset, BIT(set),
> +                                val);
> +       if (ret) {
> +               dev_err(priv->dev, "Failed to set reset bit %u\n", set);
> +               return ret;
> +       }
> +
> +
> +       ret = lantiq_rcu_reset_status_timeout(rcdev, id, assert);
> +       if (ret)
> +               dev_err(priv->dev, "Failed to %s bit %u\n",
> +                       assert ? "assert" : "deassert", set);
> +
> +       return ret;
> +}
> +
> +static int lantiq_rcu_reset_assert(struct reset_controller_dev *rcdev,
> +                            unsigned long id)
> +{
> +       return lantiq_rcu_reset_update(rcdev, id, true);
> +}
> +
> +static int lantiq_rcu_reset_deassert(struct reset_controller_dev *rcdev,
> +                              unsigned long id)
> +{
> +       return lantiq_rcu_reset_update(rcdev, id, false);
> +}
> +
> +static int lantiq_rcu_reset_reset(struct reset_controller_dev *rcdev,
> +                           unsigned long id)
> +{
> +       int ret;
> +
> +       ret = lantiq_rcu_reset_assert(rcdev, id);
> +       if (ret)
> +               return ret;
> +
> +       return lantiq_rcu_reset_deassert(rcdev, id);
> +}
> +
> +static const struct reset_control_ops lantiq_rcu_reset_ops = {
> +       .assert = lantiq_rcu_reset_assert,
> +       .deassert = lantiq_rcu_reset_deassert,
> +       .status = lantiq_rcu_reset_status,
> +       .reset  = lantiq_rcu_reset_reset,
> +};
> +
> +static int lantiq_rcu_reset_of_parse(struct platform_device *pdev,
> +                              struct lantiq_rcu_reset_priv *priv)
> +{
> +       struct device *dev = &pdev->dev;
> +       const __be32 *offset;
> +
> +       priv->regmap = syscon_node_to_regmap(dev->of_node->parent);
> +       if (IS_ERR(priv->regmap)) {
> +               dev_err(&pdev->dev, "Failed to lookup RCU regmap\n");
> +               return PTR_ERR(priv->regmap);
> +       }
> +
> +       offset = of_get_address(dev->of_node, 0, NULL, NULL);
> +       if (!offset) {
> +               dev_err(&pdev->dev, "Failed to get RCU reset offset\n");
> +               return -ENOENT;
> +       }
> +       priv->reset_offset = __be32_to_cpu(*offset);
> +
> +       offset = of_get_address(dev->of_node, 1, NULL, NULL);
> +       if (!offset) {
> +               dev_err(&pdev->dev, "Failed to get RCU status offset\n");
> +               return -ENOENT;
> +       }
> +       priv->status_offset = __be32_to_cpu(*offset);
> +
> +       return 0;
> +}
> +
> +static int lantiq_rcu_reset_xlate(struct reset_controller_dev *rcdev,
> +                                 const struct of_phandle_args *reset_spec)
> +{
> +       unsigned int status, set;
> +
> +       set = reset_spec->args[0];
> +       status = reset_spec->args[1];
> +
> +       if (set >= rcdev->nr_resets || status >= rcdev->nr_resets)
> +               return -EINVAL;
> +
> +       return (status << 8) | set;
> +}
> +
> +static int lantiq_rcu_reset_probe(struct platform_device *pdev)
> +{
> +       struct lantiq_rcu_reset_priv *priv;
> +       int err;
> +
> +       priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +       if (!priv)
> +               return -ENOMEM;
> +
> +       priv->dev = &pdev->dev;
> +       platform_set_drvdata(pdev, priv);
> +
> +       err = lantiq_rcu_reset_of_parse(pdev, priv);
> +       if (err)
> +               return err;
> +
> +       priv->rcdev.ops = &lantiq_rcu_reset_ops;
> +       priv->rcdev.owner = THIS_MODULE;
> +       priv->rcdev.of_node = pdev->dev.of_node;
> +       priv->rcdev.nr_resets = 32;
> +       priv->rcdev.of_xlate = lantiq_rcu_reset_xlate;
> +       priv->rcdev.of_reset_n_cells = 2;
> +
> +       return reset_controller_register(&priv->rcdev);
> +}
> +
> +static const struct of_device_id lantiq_rcu_reset_dt_ids[] = {
> +       { .compatible = "lantiq,danube-reset", },
> +       { .compatible = "lantiq,xrx200-reset", },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(of, lantiq_rcu_reset_dt_ids);
> +
> +static struct platform_driver lantiq_rcu_reset_driver = {
> +       .probe  = lantiq_rcu_reset_probe,
> +       .driver = {
> +               .name           = "lantiq-reset",
> +               .of_match_table = lantiq_rcu_reset_dt_ids,
> +       },
> +};
> +module_platform_driver(lantiq_rcu_reset_driver);
> +
> +MODULE_AUTHOR("Martin Blumenstingl <martin.blumenstingl-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>");
> +MODULE_DESCRIPTION("Lantiq XWAY RCU Reset Controller Driver");
> +MODULE_LICENSE("GPL");
> --
> 2.11.0
>
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