Message-ID: <20150603134951.GD12304@x1>
Date:	Wed, 3 Jun 2015 14:49:51 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Olof Johansson <olof@...om.net>,
	Doug Anderson <dianders@...omium.org>,
	Bill Richardson <wfrichar@...omium.org>,
	Simon Glass <sjg@...gle.com>,
	Gwendal Grignou <gwendal@...gle.com>,
	Stephen Barber <smbarber@...omium.org>,
	Filipe Brandenburger <filbranden@...gle.com>,
	Todd Broch <tbroch@...omium.org>,
	Alexandru M Stan <amstan@...omium.org>,
	Heiko Stuebner <heiko@...ech.de>,
	linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, Gwendal Grignou <gwendal@...omium.org>
Subject: Re: [PATCH v5 7/9] mfd: cros_ec: Support multiple EC in a system

On Wed, 03 Jun 2015, Javier Martinez Canillas wrote:

> From: Gwendal Grignou <gwendal@...omium.org>
> 
> Chromebooks can have more than one Embedded Controller so the
> cros_ec device id has to be incremented for each EC registered.
> 
> Add a new structure to represent multiple EC as different char
> devices (e.g: /dev/cros_ec, /dev/cros_pd). It connects to
> cros_ec_device and allows sysfs inferface for cros_pd.
> 
> Also reduce number of allocated objects, make chromeos sysfs
> class object a static and add refcounting to prevent object
> deletion while command is in progress.
> 
> Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
> Reviewed-by: Dmitry Torokhov <dtor@...omium.org>
> Signed-off-by: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> ---
> 
> Changes since v4:
>  - Use cros-ec-name DT property instead of devname. Suggested by Lee Jones.
>  - Pass PLATFORM_DEVID_AUTO directly to mfd_add_devices().
>    Suggested by Lee Jones.
>  - Add Heiko Stuebner tested-by tag.
>  - Fix get_version by passing the cmd_offset to EC_CMD_GET_VERSION.
> 
> Changes since v3:
>  - Add defines for the EC and PD index constants.
>  - Remove cros_ec_dev_register() and declare the mfd_cells as static structs.
>    Suggested by Lee Jones.
> 
> Changes since v2: None
> 
> Changes since v1:
>   - Squash patch that adds support to represent EC's as different
>     char devices (e.g: /dev/cros_ec, /dev/cros_pd):
>     https://chromium-review.googlesource.com/#/c/217297/
>     Suggested by Gwendal Grignou
>   - Use cros_ec instead of cros-ec in the subject line to be consistent.
>     Suggested by Gwendal Grignou
> ---
>  drivers/input/keyboard/cros_ec_keyb.c      |   2 +-
>  drivers/mfd/cros_ec.c                      |  57 +++++++++++--
>  drivers/mfd/cros_ec_i2c.c                  |   1 -
>  drivers/mfd/cros_ec_spi.c                  |   1 -
>  drivers/platform/chrome/cros_ec_dev.c      | 130 ++++++++++++++++++++---------
>  drivers/platform/chrome/cros_ec_dev.h      |   7 --
>  drivers/platform/chrome/cros_ec_lightbar.c |  75 +++++++++--------
>  drivers/platform/chrome/cros_ec_lpc.c      |   1 -
>  drivers/platform/chrome/cros_ec_sysfs.c    |  48 +++++------
>  include/linux/mfd/cros_ec.h                |  44 ++++++++--
>  10 files changed, 239 insertions(+), 127 deletions(-)
> 
> diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
> index 974154a74505..b01966dc7eb3 100644
> --- a/drivers/input/keyboard/cros_ec_keyb.c
> +++ b/drivers/input/keyboard/cros_ec_keyb.c
> @@ -275,7 +275,7 @@ static int cros_ec_keyb_probe(struct platform_device *pdev)
>  	ckdev->dev = dev;
>  	dev_set_drvdata(&pdev->dev, ckdev);
>  
> -	idev->name = ec->ec_name;
> +	idev->name = CROS_EC_DEV_NAME;
>  	idev->phys = ec->phys_name;
>  	__set_bit(EV_REP, idev->evbit);
>  
> diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
> index 08d82bfc5268..6935f385992e 100644
> --- a/drivers/mfd/cros_ec.c
> +++ b/drivers/mfd/cros_ec.c
> @@ -24,11 +24,27 @@
>  #include <linux/mfd/core.h>
>  #include <linux/mfd/cros_ec.h>
>  
> -static const struct mfd_cell cros_devs[] = {
> -	{
> -		.name = "cros-ec-ctl",
> -		.id = PLATFORM_DEVID_AUTO,
> -	},
> +#define CROS_EC_DEV_EC_INDEX 0
> +#define CROS_EC_DEV_PD_INDEX 1
> +
> +struct cros_ec_platform ec_p = {
> +	.cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_EC_INDEX),
> +};
> +
> +struct cros_ec_platform pd_p = {
> +	.cmd_offset = EC_CMD_PASSTHRU_OFFSET(CROS_EC_DEV_PD_INDEX),
> +};
> +
> +struct mfd_cell ec_cell = {
> +	.name = "cros-ec-ctl",
> +	.platform_data = &ec_p,
> +	.pdata_size = sizeof(ec_p),
> +};
> +
> +struct mfd_cell ec_pd_cell = {
> +	.name = "cros-ec-ctl",
> +	.platform_data = &pd_p,
> +	.pdata_size = sizeof(pd_p),
>  };
>  
>  int cros_ec_register(struct cros_ec_device *ec_dev)
> @@ -52,14 +68,39 @@ int cros_ec_register(struct cros_ec_device *ec_dev)
>  
>  	cros_ec_query_all(ec_dev);
>  
> -	err = mfd_add_devices(dev, 0, cros_devs,
> -			      ARRAY_SIZE(cros_devs),
> +	if (IS_ENABLED(CONFIG_OF) && dev->of_node)
> +		ec_p.ec_name = of_get_property(dev->of_node,
> +					       "google,cros-ec-name", NULL);

NACK

You either need to obtain this another way, or have a chat with the DT
Maintainers and explain why this platform is special enough to break
the normal conventions.

HINT: I different compatible string is normally more amenable, but
this will also require a DT ACK for me to take it through.

> +	if (!ec_p.ec_name)
> +		ec_p.ec_name = CROS_EC_DEV_NAME;
> +
> +	err = mfd_add_devices(ec_dev->dev, PLATFORM_DEVID_AUTO, &ec_cell, 1,
>  			      NULL, ec_dev->irq, NULL);
>  	if (err) {
> -		dev_err(dev, "failed to add mfd devices\n");
> +		dev_err(dev, "failed to add ec\n");

Might be nice to expand 'ec' so your users have half a chance in
deciphering what just went wrong.

[...]

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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