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

[Shengjiu Wang]

On Thu, May 30, 2024 at 5:06 PM Marco Felsch <m.felsch@xxxxxxxxxxxxxx> wrote:
>
> 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.

I am confused. According to below discussion:

https://lore.kernel.org/lkml/b86c83a520f0c45a60249468fa92b1de.sboyd@xxxxxxxxxx/

Stephen and Conor suggested using auxdev.


Best regards
Shengjiu Wang

>
> >  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
> >
> >
> >