Re: [PATCH v4 6/8] mfd: cros_ec: Support multiple EC in a system

[Lee Jones <lee.jones@linaro.org>]

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

> Hello Lee,
> 
> Thanks a lot for your feedback.
> 
> On 06/03/2015 10:53 AM, Lee Jones wrote:
> > On Tue, 02 Jun 2015, Javier Martinez Canillas wrote:
> > 
> >> From: Gwendal Grignou <gwendal@chromium.org>
> >> 
> >> Chromebooks can have more than one Embedded Controller so the
> >> cros_ec device id has to be incremented for each EC registered.
> >> 
> >> Add code to handle multiple EC. First ec found is cros-ec0,
> >> second cros-ec1 and so on.
> >> 
> >> 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@chromium.org>
> >> Reviewed-by: Dmitry Torokhov <dtor@chromium.org>
> >> Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
> >> ---
> >> 
> >> 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.
> >>  - Add a new line before the return statement in cros_ec_dev_register().
> >>    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                      |  59 +++++++++++--
> >>  drivers/mfd/cros_ec_i2c.c                  |   1 -
> >>  drivers/mfd/cros_ec_spi.c                  |   1 -
> >>  drivers/platform/chrome/cros_ec_dev.c      | 128 ++++++++++++++++++++---------
> >>  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, 240 insertions(+), 126 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..4fbb4ce8f81e 100644
> >> --- a/drivers/mfd/cros_ec.c
> >> +++ b/drivers/mfd/cros_ec.c
> >> @@ -24,11 +24,29 @@
> >>  #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",
> >> +	.id = PLATFORM_DEVID_AUTO,
> >> +	.platform_data = &ec_p,
> >> +	.pdata_size = sizeof(ec_p),
> >> +};
> >> +
> >> +struct mfd_cell ec_pd_cell = {
> >> +	.name = "cros-ec-ctl",
> >> +	.id = PLATFORM_DEVID_AUTO,
> >> +	.platform_data = &pd_p,
> >> +	.pdata_size = sizeof(pd_p),
> >>  };
> >>  
> >>  int cros_ec_register(struct cros_ec_device *ec_dev)
> >> @@ -52,14 +70,39 @@ 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, "devname",
> >> +					       NULL);
> > 
> > Has this binding already been accepted?  We don't normally allow
> > "device name"properties in DT.
> > 
> 
> Sigh, I now noticed that I missed the DT binding change when originally
> forward porting the patches from the downstream ChromiumOS tree. I'm so
> sorry about that.
> 
> ChromiumOS tree has in Documentation/devicetree/bindings/mfd/cros-ec.txt:
> 
> Optional properties (All):
> - devname: name of the EC. Can be based on its function: for instance,
>   for Sensor Hub, 'cros_sh', for Power Delivery MCU 'cros_pd'.
>   If not present, 'cros_ec' can be assumed.
> 
> When you say that normally device names are not allowed in DT, do you mean
> that "devname" is a too generic property name? (which I totally agree) or
> that DT bindings shouldn't have a property to change a device's name for
> something more descriptive?
> 
> Because for example, the regulator bindings has a "regulator-name" property.
> If you agree I can change the property to "google,cros-ec-name" which should
> be more precise.

I mean, no names of devices are allowed in Device Tree:

  `git grep name -- arch/arm/boot/dts/ | grep dev`

> >> +	if (!ec_p.ec_name)
> >> +		ec_p.ec_name = CROS_EC_DEV_NAME;
> >> +
> >> +	err = mfd_add_devices(ec_dev->dev, CROS_EC_DEV_EC_INDEX, &ec_cell, 1,
> >>  			      NULL, ec_dev->irq, NULL);
> > 
> > Take a look at how 'id' (second argument) is handled in mfd-core, then
> > try to figure out why what you're doing is not correct.
> >
> 
> I see, so I should not set the struct mfd_cell .id to PLATFORM_DEVID_AUTO and
> just pass PLATFORM_DEVID_AUTO to mfd_add_devices() so platform_device_add()
> automatically allocates a device ID and sets pdev->id_auto = true.
> 
> It was only working because CROS_EC_DEV_EC_INDEX was zero so id + cell->id
> was still PLATFORM_DEVID_AUTO but for CROS_EC_DEV_PD_INDEX, it was set to
> PLATFORM_DEVID_NONE...
> 
> I'll change that, thanks for pointing it out.

No problem

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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