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Date:   Sat, 29 Jun 2019 00:57:41 -0700
From:   Gwendal Grignou <gwendal@...omium.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Will Deacon <will.deacon@....com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Sebastian Reichel <sre@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Collabora kernel ML <kernel@...labora.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v4 01/11] mfd / platform: cros_ec: Handle chained ECs as
 platform devices

Review and tested the whole series:
Reviewed-by: Gwendal Grignou <gwendal@...omium.org>
Tested-by: Gwendal Grignou <gwendal@...omium.org>

On Thu, Jun 27, 2019 at 3:40 AM Enric Balletbo i Serra
<enric.balletbo@...labora.com> wrote:
>
> An MFD is a device that contains several sub-devices (cells). For instance,
> the ChromeOS EC fits in this description as usually contains a charger and
> can have other devices with different functions like a Real-Time Clock,
> an Audio codec, a Real-Time Clock, ...
>
> If you look at the driver, though, we're doing something odd. We have
> two MFD cros-ec drivers where one of them (cros-ec-core) instantiates
> another MFD driver as sub-driver (cros-ec-dev), and the latest
> instantiates the different sub-devices (Real-Time Clock, Audio codec,
> etc).
>
>                   MFD
> ------------------------------------------
>    cros-ec-core
>        |___ mfd-cellA (cros-ec-dev)
>        |       |__ mfd-cell0
>        |       |__ mfd-cell1
>        |       |__ ...
>        |
>        |___ mfd-cellB (cros-ec-dev)
>                |__ mfd-cell0
>                |__ mfd-cell1
>                |__ ...
>
> The problem that was trying to solve is to describe some kind of topology for
> the case where we have an EC (cros-ec) chained with another EC
> (cros-pd). Apart from that this extends the bounds of what MFD was
> designed to do we might be interested on have other kinds of topology that
> can't be implemented in that way.
>
> Let's prepare the code to move the cros-ec-core part from MFD to
> platform/chrome as this is clearly a platform specific thing non-related
> to a MFD device.
>
>   platform/chrome  |         MFD
> ------------------------------------------
>                    |
>    cros-ec ________|___ cros-ec-dev
>                    |       |__ mfd-cell0
>                    |       |__ mfd-cell1
>                    |       |__ ...
>                    |
>    cros-pd ________|___ cros-ec-dev
>                    |        |__ mfd-cell0
>                    |        |__ mfd-cell1
>                    |        |__ ...
>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> Acked-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Tested-by: Gwendal Grignou <gwendal@...omium.org>
> ---
>
> Changes in v4:
> - Rebase again on top of for-mfd-next to avoid conflicts.
>
> Changes in v3:
> - Collect more acks an tested-by
>
> Changes in v2:
> - Collect acks received.
> - Remove '[PATCH 07/10] mfd: cros_ec: Update with SPDX Licence identifier
>   and fix description' to avoid conflicts with some tree-wide patches
>   that actually updates the Licence identifier.
> - Add '[PATCH 10/10] arm/arm64: defconfig: Update configs to use the new
>   CROS_EC options' to update the defconfigs after change some config
>   symbols.
>
>  drivers/mfd/cros_ec.c                   | 61 +++++++++++++------------
>  drivers/platform/chrome/cros_ec_i2c.c   |  8 ++++
>  drivers/platform/chrome/cros_ec_lpc.c   |  3 +-
>  drivers/platform/chrome/cros_ec_rpmsg.c |  2 +
>  drivers/platform/chrome/cros_ec_spi.c   |  8 ++++
>  include/linux/mfd/cros_ec.h             | 18 ++++++++
>  6 files changed, 69 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index bd2bcdd4718b..11fced7917fc 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -21,7 +21,6 @@
>  #include <linux/interrupt.h>
>  #include <linux/slab.h>
>  #include <linux/module.h>
> -#include <linux/mfd/core.h>
>  #include <linux/mfd/cros_ec.h>
>  #include <linux/suspend.h>
>  #include <asm/unaligned.h>
> @@ -39,18 +38,6 @@ static struct cros_ec_platform pd_p = {
>         .cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_PD_INDEX),
>  };
>
> -static const struct mfd_cell ec_cell = {
> -       .name = "cros-ec-dev",
> -       .platform_data = &ec_p,
> -       .pdata_size = sizeof(ec_p),
> -};
> -
> -static const struct mfd_cell ec_pd_cell = {
> -       .name = "cros-ec-dev",
> -       .platform_data = &pd_p,
> -       .pdata_size = sizeof(pd_p),
> -};
> -
>  static irqreturn_t ec_irq_thread(int irq, void *data)
>  {
>         struct cros_ec_device *ec_dev = data;
> @@ -158,38 +145,42 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>                 }
>         }
>
> -       err = devm_mfd_add_devices(ec_dev->dev, PLATFORM_DEVID_AUTO, &ec_cell,
> -                                  1, NULL, ec_dev->irq, NULL);
> -       if (err) {
> -               dev_err(dev,
> -                       "Failed to register Embedded Controller subdevice %d\n",
> -                       err);
> -               return err;
> +       /* Register a platform device for the main EC instance */
> +       ec_dev->ec = platform_device_register_data(ec_dev->dev, "cros-ec-dev",
> +                                       PLATFORM_DEVID_AUTO, &ec_p,
> +                                       sizeof(struct cros_ec_platform));
> +       if (IS_ERR(ec_dev->ec)) {
> +               dev_err(ec_dev->dev,
> +                       "Failed to create CrOS EC platform device\n");
> +               return PTR_ERR(ec_dev->ec);
>         }
>
>         if (ec_dev->max_passthru) {
>                 /*
> -                * Register a PD device as well on top of this device.
> +                * Register a platform device for the PD behind the main EC.
>                  * We make the following assumptions:
>                  * - behind an EC, we have a pd
>                  * - only one device added.
>                  * - the EC is responsive at init time (it is not true for a
> -                *   sensor hub.
> +                *   sensor hub).
>                  */
> -               err = devm_mfd_add_devices(ec_dev->dev, PLATFORM_DEVID_AUTO,
> -                                     &ec_pd_cell, 1, NULL, ec_dev->irq, NULL);
> -               if (err) {
> -                       dev_err(dev,
> -                               "Failed to register Power Delivery subdevice %d\n",
> -                               err);
> -                       return err;
> +               ec_dev->pd = platform_device_register_data(ec_dev->dev,
> +                                       "cros-ec-dev",
> +                                       PLATFORM_DEVID_AUTO, &pd_p,
> +                                       sizeof(struct cros_ec_platform));
> +               if (IS_ERR(ec_dev->pd)) {
> +                       dev_err(ec_dev->dev,
> +                               "Failed to create CrOS PD platform device\n");
> +                       platform_device_unregister(ec_dev->ec);
> +                       return PTR_ERR(ec_dev->pd);
>                 }
>         }
>
>         if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
>                 err = devm_of_platform_populate(dev);
>                 if (err) {
> -                       mfd_remove_devices(dev);
> +                       platform_device_unregister(ec_dev->pd);
> +                       platform_device_unregister(ec_dev->ec);
>                         dev_err(dev, "Failed to register sub-devices\n");
>                         return err;
>                 }
> @@ -210,6 +201,16 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>  }
>  EXPORT_SYMBOL(cros_ec_register);
>
> +int cros_ec_unregister(struct cros_ec_device *ec_dev)
> +{
> +       if (ec_dev->pd)
> +               platform_device_unregister(ec_dev->pd);
> +       platform_device_unregister(ec_dev->ec);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL(cros_ec_unregister);
> +
>  #ifdef CONFIG_PM_SLEEP
>  int cros_ec_suspend(struct cros_ec_device *ec_dev)
>  {
> diff --git a/drivers/platform/chrome/cros_ec_i2c.c b/drivers/platform/chrome/cros_ec_i2c.c
> index 61d75395f86d..6bb82dfa7dae 100644
> --- a/drivers/platform/chrome/cros_ec_i2c.c
> +++ b/drivers/platform/chrome/cros_ec_i2c.c
> @@ -307,6 +307,13 @@ static int cros_ec_i2c_probe(struct i2c_client *client,
>         return 0;
>  }
>
> +static int cros_ec_i2c_remove(struct i2c_client *client)
> +{
> +       struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
> +
> +       return cros_ec_unregister(ec_dev);
> +}
> +
>  #ifdef CONFIG_PM_SLEEP
>  static int cros_ec_i2c_suspend(struct device *dev)
>  {
> @@ -357,6 +364,7 @@ static struct i2c_driver cros_ec_driver = {
>                 .pm     = &cros_ec_i2c_pm_ops,
>         },
>         .probe          = cros_ec_i2c_probe,
> +       .remove         = cros_ec_i2c_remove,
>         .id_table       = cros_ec_i2c_id,
>  };
>
> diff --git a/drivers/platform/chrome/cros_ec_lpc.c b/drivers/platform/chrome/cros_ec_lpc.c
> index c9c240fbe7c6..2c7e654cf89c 100644
> --- a/drivers/platform/chrome/cros_ec_lpc.c
> +++ b/drivers/platform/chrome/cros_ec_lpc.c
> @@ -317,6 +317,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
>
>  static int cros_ec_lpc_remove(struct platform_device *pdev)
>  {
> +       struct cros_ec_device *ec_dev = platform_get_drvdata(pdev);
>         struct acpi_device *adev;
>
>         adev = ACPI_COMPANION(&pdev->dev);
> @@ -324,7 +325,7 @@ static int cros_ec_lpc_remove(struct platform_device *pdev)
>                 acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
>                                            cros_ec_lpc_acpi_notify);
>
> -       return 0;
> +       return cros_ec_unregister(ec_dev);
>  }
>
>  static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
> diff --git a/drivers/platform/chrome/cros_ec_rpmsg.c b/drivers/platform/chrome/cros_ec_rpmsg.c
> index 5d3fb2abad1d..520e507bfa54 100644
> --- a/drivers/platform/chrome/cros_ec_rpmsg.c
> +++ b/drivers/platform/chrome/cros_ec_rpmsg.c
> @@ -233,6 +233,8 @@ static void cros_ec_rpmsg_remove(struct rpmsg_device *rpdev)
>         struct cros_ec_device *ec_dev = dev_get_drvdata(&rpdev->dev);
>         struct cros_ec_rpmsg *ec_rpmsg = ec_dev->priv;
>
> +       cros_ec_unregister(ec_dev);
> +
>         cancel_work_sync(&ec_rpmsg->host_event_work);
>  }
>
> diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
> index 8e9451720e73..02f9e8257581 100644
> --- a/drivers/platform/chrome/cros_ec_spi.c
> +++ b/drivers/platform/chrome/cros_ec_spi.c
> @@ -743,6 +743,13 @@ static int cros_ec_spi_probe(struct spi_device *spi)
>         return 0;
>  }
>
> +static int cros_ec_spi_remove(struct spi_device *spi)
> +{
> +       struct cros_ec_device *ec_dev = spi_get_drvdata(spi);
> +
> +       return cros_ec_unregister(ec_dev);
> +}
> +
>  #ifdef CONFIG_PM_SLEEP
>  static int cros_ec_spi_suspend(struct device *dev)
>  {
> @@ -781,6 +788,7 @@ static struct spi_driver cros_ec_driver_spi = {
>                 .pm     = &cros_ec_spi_pm_ops,
>         },
>         .probe          = cros_ec_spi_probe,
> +       .remove         = cros_ec_spi_remove,
>         .id_table       = cros_ec_spi_id,
>  };
>
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 751cb3756d49..669962ac392b 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -129,6 +129,10 @@ struct cros_ec_command {
>   * @event_data: Raw payload transferred with the MKBP event.
>   * @event_size: Size in bytes of the event data.
>   * @host_event_wake_mask: Mask of host events that cause wake from suspend.
> + * @ec: The platform_device used by the mfd driver to interface with the
> + *      main EC.
> + * @pd: The platform_device used by the mfd driver to interface with the
> + *      PD behind an EC.
>   */
>  struct cros_ec_device {
>         /* These are used by other drivers that want to talk to the EC */
> @@ -164,6 +168,10 @@ struct cros_ec_device {
>         struct ec_response_get_next_event_v1 event_data;
>         int event_size;
>         u32 host_event_wake_mask;
> +
> +       /* The platform devices used by the mfd driver */
> +       struct platform_device *ec;
> +       struct platform_device *pd;
>  };
>
>  /**
> @@ -298,6 +306,16 @@ int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
>   */
>  int cros_ec_register(struct cros_ec_device *ec_dev);
>
> +/**
> + * cros_ec_unregister() - Remove a ChromeOS EC.
> + * @ec_dev: Device to unregister.
> + *
> + * Call this to deregister a ChromeOS EC, then clean up any private data.
> + *
> + * Return: 0 on success or negative error code.
> + */
> +int cros_ec_unregister(struct cros_ec_device *ec_dev);
> +
>  /**
>   * cros_ec_query_all() -  Query the protocol version supported by the
>   *         ChromeOS EC.
> --
> 2.20.1
>

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