[U-Boot] [PATCH v1 1/4] drivers: Add a new framework for multiplexer devices

Simon Glass sjg at chromium.org
Wed Oct 30 01:48:47 UTC 2019


Hi Jean-Jacques,

On Wed, 2 Oct 2019 at 06:47, Jean-Jacques Hiblot <jjhiblot at ti.com> wrote:
>
> Add a new subsystem that handles multiplexer controllers. The API is the
> same as in Linux.
>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
> ---
>
>  drivers/Kconfig               |   2 +
>  drivers/Makefile              |   1 +
>  drivers/mux/Kconfig           |   7 +
>  drivers/mux/Makefile          |   6 +
>  drivers/mux/mux-uclass.c      | 296 ++++++++++++++++++++++++++++++++++
>  include/dm/uclass-id.h        |   1 +
>  include/dt-bindings/mux/mux.h |  17 ++
>  include/mux-internal.h        |  80 +++++++++
>  include/mux.h                 | 114 +++++++++++++
>  9 files changed, 524 insertions(+)
>  create mode 100644 drivers/mux/Kconfig
>  create mode 100644 drivers/mux/Makefile
>  create mode 100644 drivers/mux/mux-uclass.c
>  create mode 100644 include/dt-bindings/mux/mux.h
>  create mode 100644 include/mux-internal.h
>  create mode 100644 include/mux.h
>

I feel this needs more documentation. What is a multiplexer?

> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 350acf81f3..5334974ad4 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -60,6 +60,8 @@ source "drivers/mmc/Kconfig"
>
>  source "drivers/mtd/Kconfig"
>
> +source "drivers/mux/Kconfig"
> +
>  source "drivers/net/Kconfig"
>
>  source "drivers/nvme/Kconfig"
> diff --git a/drivers/Makefile b/drivers/Makefile
> index a4bb5e4975..f4d71f3b3c 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_$(SPL_TPL_)INPUT) += input/
>  obj-$(CONFIG_$(SPL_TPL_)LED) += led/
>  obj-$(CONFIG_$(SPL_TPL_)MMC_SUPPORT) += mmc/
>  obj-$(CONFIG_$(SPL_TPL_)NAND_SUPPORT) += mtd/nand/raw/
> +obj-$(CONFIG_$(SPl_)MULTIPLEXER) += mux/

SPL?

>  obj-$(CONFIG_$(SPL_TPL_)PCH_SUPPORT) += pch/
>  obj-$(CONFIG_$(SPL_TPL_)PCI) += pci/
>  obj-$(CONFIG_$(SPL_TPL_)PHY) += phy/
> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
> new file mode 100644
> index 0000000000..ad0199c058
> --- /dev/null
> +++ b/drivers/mux/Kconfig
> @@ -0,0 +1,7 @@
> +menu "Multiplexer drivers"
> +
> +config MULTIPLEXER
> +       bool "Multiplexer Support"
> +       depends on DM
> +
> +endmenu
> diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
> new file mode 100644
> index 0000000000..351e4363d3
> --- /dev/null
> +++ b/drivers/mux/Makefile
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: GPL-2.0+
> +#
> +# (C) Copyright 2019
> +# Jean-Jacques Hiblot <jjhiblot at ti.com>
> +
> +obj-$(CONFIG_$(SPL_)MULTIPLEXER) += mux-uclass.o
> diff --git a/drivers/mux/mux-uclass.c b/drivers/mux/mux-uclass.c
> new file mode 100644
> index 0000000000..58998af29c
> --- /dev/null
> +++ b/drivers/mux/mux-uclass.c
> @@ -0,0 +1,296 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Multiplexer subsystem
> + *
> + * Based on the linux multiplexer framework
> + *
> + * Copyright (C) 2017 Axentia Technologies AB
> + * Author: Peter Rosin <peda at axentia.se>
> + *
> + * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
> + * Jean-Jacques Hiblot <jjhiblot at ti.com>
> + */
> +
> +#include <common.h>
> +#include <mux-internal.h>

should go above the dm/device-internal

> +#include <dm.h>
> +#include <dt-structs.h>

Shouldn't need this
> +#include <errno.h>

Shouldn't need this

> +#include <dm/device-internal.h>
> +#include <dm/lists.h>
> +#include <dm/read.h>

Shouldn't need this

> +#include <dt-bindings/mux/mux.h>
> +
> +/*
> + * The idle-as-is "state" is not an actual state that may be selected, it
> + * only implies that the state should not be changed. So, use that state
> + * as indication that the cached state of the multiplexer is unknown.
> + */
> +#define MUX_CACHE_UNKNOWN MUX_IDLE_AS_IS
> +
> +static inline const struct mux_control_ops *mux_dev_ops(struct udevice *dev)
> +{
> +       return (const struct mux_control_ops *)dev->driver->ops;
> +}
> +
> +static int mux_control_set(struct mux_control *mux, int state)
> +{
> +       int ret = mux_dev_ops(mux->dev)->set(mux, state);
> +
> +       mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
> +
> +       return ret;
> +}
> +
> +unsigned int mux_control_states(struct mux_control *mux)
> +{
> +       return mux->states;
> +}
> +
> +static int __mux_control_select(struct mux_control *mux, int state)
> +{
> +       int ret;
> +
> +       if (WARN_ON(state < 0 || state >= mux->states))
> +               return -EINVAL;
> +
> +       if (mux->cached_state == state)
> +               return 0;
> +
> +       ret = mux_control_set(mux, state);
> +       if (ret >= 0)
> +               return 0;
> +
> +       /* The mux update failed, try to revert if appropriate... */
> +       if (mux->idle_state != MUX_IDLE_AS_IS)
> +               mux_control_set(mux, mux->idle_state);
> +
> +       return ret;
> +}
> +
> +int mux_control_select(struct mux_control *mux, unsigned int state)
> +{
> +       int ret;
> +
> +       if (mux->in_use)
> +               return -EBUSY;
> +
> +       ret = __mux_control_select(mux, state);
> +
> +       if (ret < 0)
> +               return ret;
> +
> +       mux->in_use = true;
> +
> +       return 0;
> +}
> +
> +int mux_control_deselect(struct mux_control *mux)
> +{
> +       int ret = 0;
> +
> +       if (mux->idle_state != MUX_IDLE_AS_IS &&
> +           mux->idle_state != mux->cached_state)
> +               ret = mux_control_set(mux, mux->idle_state);
> +
> +       mux->in_use = false;
> +
> +       return ret;
> +}
> +
> +static int mux_of_xlate_default(struct mux_chip *mux_chip,
> +                               struct ofnode_phandle_args *args,
> +                               struct mux_control **muxp)
> +{
> +       struct mux_control *mux;
> +       int id;
> +
> +       debug("%s(mux=%p)\n", __func__, mux);
> +
> +       if (args->args_count > 1) {
> +               debug("Invaild args_count: %d\n", args->args_count);
> +               return -EINVAL;
> +       }
> +
> +       if (args->args_count)
> +               id = args->args[0];
> +       else
> +               id = 0;
> +
> +       if (id >= mux_chip->controllers) {
> +               dev_err(dev, "bad mux controller %u specified in %s\n",
> +                       id, ofnode_get_name(args->node));
> +               return -ERANGE;
> +       }
> +
> +       mux = &mux_chip->mux[id];
> +       mux->id = id;
> +       *muxp = mux;
> +       return 0;
> +}
> +
> +static int mux_get_by_indexed_prop(struct udevice *dev, const char *prop_name,
> +                                  int index, struct mux_control **mux)
> +{
> +       int ret;
> +       struct ofnode_phandle_args args;
> +       struct udevice *dev_mux;
> +       const struct mux_control_ops *ops;
> +       struct mux_chip *mux_chip;
> +
> +       debug("%s(dev=%p, index=%d, mux=%p)\n", __func__, dev, index, mux);
> +
> +       ret = dev_read_phandle_with_args(dev, prop_name, "#mux-control-cells",
> +                                        0, index, &args);
> +       if (ret) {
> +               debug("%s: fdtdec_parse_phandle_with_args failed: err=%d\n",
> +                     __func__, ret);
> +               return ret;
> +       }
> +
> +       ret = uclass_get_device_by_ofnode(UCLASS_MUX, args.node, &dev_mux);
> +       if (ret) {
> +               debug("%s: uclass_get_device_by_ofnode failed: err=%d\n",
> +                     __func__, ret);
> +               return ret;
> +       }
> +
> +       mux_chip = dev_get_uclass_priv(dev_mux);
> +
> +       ops = mux_dev_ops(dev_mux);
> +       if (ops->of_xlate)
> +               ret = ops->of_xlate(mux_chip, &args, mux);
> +       else
> +               ret = mux_of_xlate_default(mux_chip, &args, mux);
> +       if (ret) {
> +               debug("of_xlate() failed: %d\n", ret);
> +               return ret;
> +       }
> +       (*mux)->dev = dev_mux;
> +
> +       return 0;
> +}
> +
> +int mux_get_by_index(struct udevice *dev, int index, struct mux_control **mux)
> +{
> +       return mux_get_by_indexed_prop(dev, "mux-controls", index, mux);
> +}
> +
> +int mux_control_get(struct udevice *dev, const char *name,
> +                   struct mux_control **mux)
> +{
> +       int index;
> +
> +       debug("%s(dev=%p, name=%s, mux=%p)\n", __func__, dev, name, mux);
> +
> +       index = dev_read_stringlist_search(dev, "mux-control-names", name);
> +       if (index < 0) {
> +               debug("fdt_stringlist_search() failed: %d\n", index);
> +               return index;
> +       }
> +
> +       return mux_get_by_index(dev, index, mux);
> +}
> +
> +void mux_control_put(struct mux_control *mux)
> +{
> +       mux_control_deselect(mux);
> +}
> +
> +static void devm_mux_control_release(struct udevice *dev, void *res)
> +{
> +       mux_control_put(*(struct mux_control **)res);
> +}
> +
> +struct mux_control *devm_mux_control_get(struct udevice *dev, const char *id)
> +{
> +       int rc;
> +       struct mux_control **mux;
> +
> +       mux = devres_alloc(devm_mux_control_release,
> +                          sizeof(struct mux_control *), __GFP_ZERO);
> +       if (unlikely(!mux))
> +               return ERR_PTR(-ENOMEM);
> +
> +       rc = mux_control_get(dev, id, mux);
> +       if (rc)
> +               return ERR_PTR(rc);
> +
> +       devres_add(dev, mux);
> +       return *mux;
> +}
> +
> +int mux_alloc_controllers(struct udevice *dev, unsigned int controllers)
> +{
> +       int i;
> +       struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
> +
> +       mux_chip->mux = devm_kmalloc(dev,
> +                                    sizeof(struct mux_control) * controllers,
> +                                    __GFP_ZERO);
> +       if (!mux_chip->mux)
> +               return -ENOMEM;
> +
> +       mux_chip->controllers = controllers;
> +
> +       for (i = 0; i < mux_chip->controllers; ++i) {
> +               struct mux_control *mux = &mux_chip->mux[i];
> +
> +               mux->dev = dev;
> +               mux->cached_state = MUX_CACHE_UNKNOWN;
> +               mux->idle_state = MUX_IDLE_AS_IS;
> +               mux->in_use = false;
> +               mux->id = i;
> +       }
> +
> +       return 0;
> +}
> +
> +int mux_uclass_post_probe(struct udevice *dev)
> +{
> +       int i, ret;
> +       struct mux_chip *mux_chip = dev_get_uclass_priv(dev);
> +
> +       for (i = 0; i < mux_chip->controllers; ++i) {
> +               struct mux_control *mux = &mux_chip->mux[i];
> +
> +               if (mux->idle_state == mux->cached_state)
> +                       continue;
> +
> +               ret = mux_control_set(mux, mux->idle_state);
> +               if (ret < 0) {
> +                       dev_err(&mux_chip->dev, "unable to set idle state\n");
> +                       return ret;
> +               }
> +       }
> +       return 0;
> +}
> +
> +void dm_mux_init(void)
> +{
> +       struct uclass *uc;
> +       struct udevice *dev;
> +       int ret;
> +
> +       ret = uclass_get(UCLASS_MUX, &uc);
> +       if (ret < 0) {
> +               debug("unable to get MUX uclass\n");
> +               return;
> +       }
> +       uclass_foreach_dev(dev, uc) {
> +               if (dev_read_bool(dev, "u-boot,mux-autoprobe")) {
> +                       ret = device_probe(dev);
> +                       if (ret)
> +                               debug("unable to probe device %s\n", dev->name);
> +               } else {
> +                       printf("not found for dev %s\n", dev->name);
> +               }
> +       }
> +}
> +
> +UCLASS_DRIVER(mux) = {
> +       .id             = UCLASS_MUX,
> +       .name           = "mux",
> +       .post_probe     = mux_uclass_post_probe,
> +       .per_device_auto_alloc_size = sizeof(struct mux_chip),
> +};
> diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
> index d4d96106b3..869c0616bd 100644
> --- a/include/dm/uclass-id.h
> +++ b/include/dm/uclass-id.h
> @@ -64,6 +64,7 @@ enum uclass_id {
>         UCLASS_MMC,             /* SD / MMC card or chip */
>         UCLASS_MOD_EXP,         /* RSA Mod Exp device */
>         UCLASS_MTD,             /* Memory Technology Device (MTD) device */
> +       UCLASS_MUX,             /* Multiplexer device */
>         UCLASS_NOP,             /* No-op devices */
>         UCLASS_NORTHBRIDGE,     /* Intel Northbridge / SDRAM controller */
>         UCLASS_NVME,            /* NVM Express device */
> diff --git a/include/dt-bindings/mux/mux.h b/include/dt-bindings/mux/mux.h
> new file mode 100644
> index 0000000000..042719218d
> --- /dev/null
> +++ b/include/dt-bindings/mux/mux.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * This header provides constants for most Multiplexer bindings.
> + *
> + * Most Multiplexer bindings specify an idle state. In most cases, the
> + * the multiplexer can be left as is when idle, and in some cases it can
> + * disconnect the input/output and leave the multiplexer in a high
> + * impedance state.

<add more details...what is a mux?>

How do I use this API?

> + */
> +
> +#ifndef _DT_BINDINGS_MUX_MUX_H
> +#define _DT_BINDINGS_MUX_MUX_H
> +
> +#define MUX_IDLE_AS_IS      (-1)
> +#define MUX_IDLE_DISCONNECT (-2)
> +
> +#endif
> diff --git a/include/mux-internal.h b/include/mux-internal.h
> new file mode 100644
> index 0000000000..63444f4c3d
> --- /dev/null
> +++ b/include/mux-internal.h
> @@ -0,0 +1,80 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Based on the linux multiplexer framework
> + *
> + * Copyright (C) 2017 Axentia Technologies AB
> + * Author: Peter Rosin <peda at axentia.se>
> + *
> + * Copyright (C) 2017-2018 Texas Instruments Incorporated - http://www.ti.com/
> + * Jean-Jacques Hiblot <jjhiblot at ti.com>
> + */
> +
> +#ifndef _MUX_UCLASS_H
> +#define _MUX_UCLASS_H
> +
> +/* See mux.h for background documentation. */
> +
> +#include <mux.h>
> +
> +struct ofnode_phandle_args;
> +
> +/**
> + * struct mux_chip -   Represents a chip holding mux controllers.
> + * @controllers:       Number of mux controllers handled by the chip.
> + * @mux:               Array of mux controllers that are handled.
> + * @dev:               Device structure.
> + * @ops:               Mux controller operations.

Mention that this is per-device uclass-private data.

> + */
> +struct mux_chip {
> +       unsigned int controllers;
> +       struct mux_control *mux;
> +};
> +
> +/**
> + * struct mux_control_ops -    Mux controller operations for a mux chip.
> + * @set:                       Set the state of the given mux controller.
> + */
> +struct mux_control_ops {
> +       int (*set)(struct mux_control *mux, int state);
> +       int (*of_xlate)(struct mux_chip *dev_mux,
> +                       struct ofnode_phandle_args *args,
> +                       struct mux_control **mux);

Function comments

> +};
> +
> +/**
> + * struct mux_control -        Represents a mux controller.
> + * @chip:              The mux chip that is handling this mux controller.
> + * @cached_state:      The current mux controller state, or -1 if none.
> + * @states:            The number of mux controller states.
> + * @idle_state:                The mux controller state to use when inactive, or one
> + *                     of MUX_IDLE_AS_IS and MUX_IDLE_DISCONNECT.
> + *
> + * Mux drivers may only change @states and @idle_state, and may only do so
> + * between allocation and registration of the mux controller. Specifically,
> + * @cached_state is internal to the mux core and should never be written by
> + * mux drivers.

How do I get from a struct udevice * to this struct? Is it private data?

> + */
> +struct mux_control {
> +       bool    in_use;
> +       struct udevice *dev;
> +       int cached_state;
> +       unsigned int states;
> +       int idle_state;
> +       int id;
> +};
> +
> +/**
> + * mux_control_get_index() - Get the index of the given mux controller
> + * @mux: The mux-control to get the index for.
> + *
> + * Return: The index of the mux controller within the mux chip the mux
> + * controller is a part of.
> + */
> +static inline unsigned int mux_control_get_index(struct mux_control *mux)
> +{
> +       return mux->id;
> +}
> +
> +int mux_alloc_controllers(struct udevice *dev, unsigned int controllers);
> +
> +#endif

[..]

Regards,
Simon


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