Re: [PATCH v6 3/5] reset: imx-aux: Add i.MX auxiliary reset driver

[Marco Felsch]

Hi,

On 24-05-30, Shengjiu Wang wrote:
> Add support for the resets on i.MX8MP Audio Block Control module,
> which includes the EARC PHY software reset and EARC controller
> software reset. The reset controller is created using the auxiliary
> device framework and set up in the clock driver.
> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> ---
>  drivers/reset/Kconfig         |   8 ++
>  drivers/reset/Makefile        |   1 +
>  drivers/reset/reset-imx-aux.c | 217 ++++++++++++++++++++++++++++++++++
			    ^
You make use of the auxiliary bus but this isn't a aux driver, it's the
i.MX8MP EARC reset driver. According the TRM only the EARC reset bits
are covered by the AUDIOMIX blk-ctrl.

>  3 files changed, 226 insertions(+)
>  create mode 100644 drivers/reset/reset-imx-aux.c
> 
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index 7112f5932609..38fdf05b326b 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -91,6 +91,14 @@ config RESET_IMX7
>  	help
>  	  This enables the reset controller driver for i.MX7 SoCs.
>  
> +config RESET_IMX_AUX
> +	tristate "i.MX Auxiliary Reset Driver"
			^
              Same applies here

> +	depends on CLK_IMX8MP
> +	select AUXILIARY_BUS
> +	default CLK_IMX8MP
> +	help
> +	  This enables the auxiliary reset controller driver for i.MX.
> +
>  config RESET_INTEL_GW
>  	bool "Intel Reset Controller Driver"
>  	depends on X86 || COMPILE_TEST
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index fd8b49fa46fc..f078da14c327 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
>  obj-$(CONFIG_RESET_GPIO) += reset-gpio.o
>  obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
> +obj-$(CONFIG_RESET_IMX_AUX) += reset-imx-aux.o
>  obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o
>  obj-$(CONFIG_RESET_K210) += reset-k210.o
>  obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
> diff --git a/drivers/reset/reset-imx-aux.c b/drivers/reset/reset-imx-aux.c
> new file mode 100644
> index 000000000000..61c353abc84e
> --- /dev/null
> +++ b/drivers/reset/reset-imx-aux.c
> @@ -0,0 +1,217 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright 2024 NXP
> + */
> +
> +#include <linux/auxiliary_bus.h>
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +
> +/*
> + * The reset does not support the feature and corresponding
> + * values are not valid
> + */
> +#define ASSERT_NONE     BIT(0)
> +#define DEASSERT_NONE   BIT(1)
> +#define STATUS_NONE     BIT(2)
> +
> +/* When set this function is activated by setting(vs clearing) this bit */
> +#define ASSERT_SET      BIT(3)
> +#define DEASSERT_SET    BIT(4)
> +#define STATUS_SET      BIT(5)
> +
> +/* The following are the inverse of the above and are added for consistency */
> +#define ASSERT_CLEAR    (0 << 3)
> +#define DEASSERT_CLEAR  (0 << 4)
> +#define STATUS_CLEAR    (0 << 5)
> +
> +/**
> + * struct imx_reset_ctrl - reset control structure
> + * @assert_offset: reset assert control register offset
> + * @assert_bit: reset assert bit in the reset assert control register
> + * @deassert_offset: reset deassert control register offset
> + * @deassert_bit: reset deassert bit in the reset deassert control register
> + * @status_offset: reset status register offset
> + * @status_bit: reset status bit in the reset status register
> + * @flags: reset flag indicating how the (de)assert and status are handled
> + */
> +struct imx_reset_ctrl {
> +	u32 assert_offset;
> +	u32 assert_bit;
> +	u32 deassert_offset;
> +	u32 deassert_bit;
> +	u32 status_offset;
> +	u32 status_bit;
> +	u32 flags;
> +};

Why do we make it this compicated for an simple EARC module reset? I
understand that you want to provide a generic driver which can be
re-used but there is actual no other user and may will get no other user
in the future too. Therefore I would like to keep it simple at the
begin and adapt the code on-demand.

Regards,
  Marco

> +struct imx_reset_data {
> +	const struct imx_reset_ctrl *rst_ctrl;
> +	size_t rst_ctrl_num;
> +};
> +
> +struct imx_aux_reset_priv {
> +	struct reset_controller_dev rcdev;
> +	void __iomem *base;
> +	const struct imx_reset_data *data;
> +};
> +
> +static int imx_aux_reset_assert(struct reset_controller_dev *rcdev,
> +				unsigned long id)
> +{
> +	struct imx_aux_reset_priv *priv = container_of(rcdev,
> +					struct imx_aux_reset_priv, rcdev);
> +	const struct imx_reset_data *data = priv->data;
> +	void __iomem *reg_addr = priv->base;
> +	const struct imx_reset_ctrl *ctrl;
> +	unsigned int mask, value, reg;
> +
> +	if (id >= data->rst_ctrl_num)
> +		return -EINVAL;
> +
> +	ctrl = &data->rst_ctrl[id];
> +
> +	/* assert not supported for this reset */
> +	if (ctrl->flags & ASSERT_NONE)
> +		return -EOPNOTSUPP;
> +
> +	mask = BIT(ctrl->assert_bit);
> +	value = (ctrl->flags & ASSERT_SET) ? mask : 0x0;
> +
> +	reg = readl(reg_addr + ctrl->assert_offset);
> +	writel(reg | value, reg_addr + ctrl->assert_offset);
> +
> +	return 0;
> +}
> +
> +static int imx_aux_reset_deassert(struct reset_controller_dev *rcdev,
> +				  unsigned long id)
> +{
> +	struct imx_aux_reset_priv *priv = container_of(rcdev,
> +					struct imx_aux_reset_priv, rcdev);
> +	const struct imx_reset_data *data = priv->data;
> +	void __iomem *reg_addr = priv->base;
> +	const struct imx_reset_ctrl *ctrl;
> +	unsigned int mask, value, reg;
> +
> +	if (id >= data->rst_ctrl_num)
> +		return -EINVAL;
> +
> +	ctrl = &data->rst_ctrl[id];
> +
> +	/* deassert not supported for this reset */
> +	if (ctrl->flags & DEASSERT_NONE)
> +		return -EOPNOTSUPP;
> +
> +	mask = BIT(ctrl->deassert_bit);
> +	value = (ctrl->flags & DEASSERT_SET) ? mask : 0x0;
> +
> +	reg = readl(reg_addr + ctrl->deassert_offset);
> +	writel(reg | value, reg_addr + ctrl->deassert_offset);
> +
> +	return 0;
> +}
> +
> +static int imx_aux_reset_status(struct reset_controller_dev *rcdev,
> +				unsigned long id)
> +{
> +	struct imx_aux_reset_priv *priv = container_of(rcdev,
> +					struct imx_aux_reset_priv, rcdev);
> +	const struct imx_reset_data *data = priv->data;
> +	void __iomem *reg_addr = priv->base;
> +	const struct imx_reset_ctrl *ctrl;
> +	unsigned int reset_state;
> +
> +	if (id >= data->rst_ctrl_num)
> +		return -EINVAL;
> +
> +	ctrl = &data->rst_ctrl[id];
> +
> +	/* status not supported for this reset */
> +	if (ctrl->flags & STATUS_NONE)
> +		return -EOPNOTSUPP;
> +
> +	reset_state = readl(reg_addr + ctrl->status_offset);
> +
> +	return !(reset_state & BIT(ctrl->status_bit)) ==
> +		!(ctrl->flags & STATUS_SET);
> +}
> +
> +static const struct reset_control_ops imx_aux_reset_ops = {
> +	.assert   = imx_aux_reset_assert,
> +	.deassert = imx_aux_reset_deassert,
> +	.status	  = imx_aux_reset_status,
> +};
> +
> +static int imx_aux_reset_probe(struct auxiliary_device *adev,
> +			       const struct auxiliary_device_id *id)
> +{
> +	struct imx_reset_data *data = (struct imx_reset_data *)(id->driver_data);
> +	struct imx_aux_reset_priv *priv;
> +	struct device *dev = &adev->dev;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->rcdev.owner     = THIS_MODULE;
> +	priv->rcdev.nr_resets = data->rst_ctrl_num;
> +	priv->rcdev.ops       = &imx_aux_reset_ops;
> +	priv->rcdev.of_node   = dev->parent->of_node;
> +	priv->rcdev.dev	      = dev;
> +	priv->rcdev.of_reset_n_cells = 1;
> +	priv->base            = of_iomap(dev->parent->of_node, 0);
> +	priv->data            = data;
> +
> +	return devm_reset_controller_register(dev, &priv->rcdev);
> +}
> +
> +#define EARC  0x200
> +
> +static const struct imx_reset_ctrl imx8mp_audiomix_rst_ctrl[] = {
> +	{
> +		.assert_offset = EARC,
> +		.assert_bit = 0,
> +		.deassert_offset = EARC,
> +		.deassert_bit = 0,
> +		.flags  = ASSERT_CLEAR | DEASSERT_SET | STATUS_NONE,
> +	},
> +	{
> +		.assert_offset = EARC,
> +		.assert_bit = 1,
> +		.deassert_offset = EARC,
> +		.deassert_bit = 1,
> +		.flags  = ASSERT_CLEAR | DEASSERT_SET | STATUS_NONE,
> +	},
> +};
> +
> +static const struct imx_reset_data imx8mp_audiomix_rst_data = {
> +	.rst_ctrl = imx8mp_audiomix_rst_ctrl,
> +	.rst_ctrl_num = ARRAY_SIZE(imx8mp_audiomix_rst_ctrl),
> +};
> +
> +static const struct auxiliary_device_id imx_aux_reset_ids[] = {
> +	{
> +		.name = "clk_imx8mp_audiomix.reset",
> +		.driver_data = (kernel_ulong_t)&imx8mp_audiomix_rst_data,
> +	},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(auxiliary, imx_aux_reset_ids);
> +
> +static struct auxiliary_driver imx_aux_reset_driver = {
> +	.probe		= imx_aux_reset_probe,
> +	.id_table	= imx_aux_reset_ids,
> +};
> +
> +module_auxiliary_driver(imx_aux_reset_driver);
> +
> +MODULE_AUTHOR("Shengjiu Wang <shengjiu.wang@xxxxxxx>");
> +MODULE_DESCRIPTION("Freescale i.MX auxiliary reset driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.34.1
> 
> 
>