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Date:   Mon, 27 Jun 2022 15:43:18 +0100
From:   Lee Jones <lee.jones@linaro.org>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     frank zago <frank@zago.net>, linux-kernel@vger.kernel.org,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Wolfram Sang <wsa@kernel.org>, Johan Hovold <johan@kernel.org>,
        linux-usb@vger.kernel.org,
        Linus Walleij <linus.walleij@linaro.org>,
        linux-gpio@vger.kernel.org, linux-i2c@vger.kernel.org
Subject: Re: [PATCH v6 1/4] mfd: ch341: add core driver for the WCH CH341 in
 I2C/SPI/GPIO mode
Message-ID: <YrnCBpvA8/y38Brg@google.com>
References: <20220616013747.126051-1-frank@zago.net>
 <20220616013747.126051-2-frank@zago.net>
 <Yrm48AYxkmoUgdwr@google.com>
 <Yrm+kH6NvTy5A9WO@kroah.com>
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Precedence: bulk

On Mon, 27 Jun 2022, Greg Kroah-Hartman wrote:

> On Mon, Jun 27, 2022 at 03:04:32PM +0100, Lee Jones wrote:
> > USB review please.
> > 
> > > The CH341 is a multifunction chip, presenting 3 different USB PID. One
> > > 
> > > of these functions is for I2C/SPI/GPIO. This new set of drivers will
> > > manage I2C and GPIO.
> > > 
> > > Signed-off-by: frank zago <frank@zago.net>
> > > ---
> > >  MAINTAINERS               |  7 +++
> > >  drivers/mfd/Kconfig       | 10 +++++
> > >  drivers/mfd/Makefile      |  1 +
> > >  drivers/mfd/ch341-core.c  | 90 +++++++++++++++++++++++++++++++++++++++
> > >  include/linux/mfd/ch341.h | 18 ++++++++
> > >  5 files changed, 126 insertions(+)
> > >  create mode 100644 drivers/mfd/ch341-core.c
> > >  create mode 100644 include/linux/mfd/ch341.h
> > > 
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 43d3d07afccd..628eeaa9bf68 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -21475,6 +21475,13 @@ M:	David Härdeman <david@hardeman.nu>
> > >  S:	Maintained
> > >  F:	drivers/media/rc/winbond-cir.c
> > >  
> > > +WINCHIPHEAD CH341 I2C/GPIO MFD DRIVER
> > > +M:	Frank Zago <frank@zago.net>
> > > +L:	linux-usb@vger.kernel.org
> > > +S:	Maintained
> > > +F:	drivers/mfd/ch341-core.c
> > > +F:	include/linux/mfd/ch341.h
> > > +
> > >  WINSYSTEMS EBC-C384 WATCHDOG DRIVER
> > >  M:	William Breathitt Gray <vilhelm.gray@gmail.com>
> > >  L:	linux-watchdog@vger.kernel.org
> > > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > > index 3b59456f5545..893acc821a42 100644
> > > --- a/drivers/mfd/Kconfig
> > > +++ b/drivers/mfd/Kconfig
> > > @@ -1784,6 +1784,16 @@ config MFD_LOCHNAGAR
> > >  	help
> > >  	  Support for Cirrus Logic Lochnagar audio development board.
> > >  
> > > +config MFD_CH341
> > > +	tristate "WinChipHead CH341 in I2C/SPI/GPIO mode"
> > > +	depends on USB
> > > +	help
> > > +	  If you say yes to this option, support for the CH341 series
> > > +	  of chips, running in I2C/SPI/GPIO mode will be included.
> > > +
> > > +	  This driver can also be built as a module.  If so, the
> > > +	  module will be called ch341-core.
> > > +
> > >  config MFD_ARIZONA
> > >  	select REGMAP
> > >  	select REGMAP_IRQ
> > > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > > index 858cacf659d6..fd615ab3929f 100644
> > > --- a/drivers/mfd/Makefile
> > > +++ b/drivers/mfd/Makefile
> > > @@ -13,6 +13,7 @@ obj-$(CONFIG_MFD_ASIC3)		+= asic3.o tmio_core.o
> > >  obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835-pm.o
> > >  obj-$(CONFIG_MFD_BCM590XX)	+= bcm590xx.o
> > >  obj-$(CONFIG_MFD_BD9571MWV)	+= bd9571mwv.o
> > > +obj-$(CONFIG_MFD_CH341)		+= ch341-core.o
> > >  obj-$(CONFIG_MFD_CROS_EC_DEV)	+= cros_ec_dev.o
> > >  obj-$(CONFIG_MFD_ENE_KB3930)	+= ene-kb3930.o
> > >  obj-$(CONFIG_MFD_EXYNOS_LPASS)	+= exynos-lpass.o
> > > diff --git a/drivers/mfd/ch341-core.c b/drivers/mfd/ch341-core.c
> > > new file mode 100644
> > > index 000000000000..f08a67dd6074
> > > --- /dev/null
> > > +++ b/drivers/mfd/ch341-core.c
> > > @@ -0,0 +1,90 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Core driver for the CH341A, CH341B and CH341T in I2C/SPI/GPIO
> > > + * mode. There are cell drivers available for I2C and GPIO. SPI is not
> > > + * yet supported.
> > > + *
> > > + * Copyright 2022, Frank Zago
> > > + * Copyright (c) 2017 Gunar Schorcht (gunar@schorcht.net)
> > > + * Copyright (c) 2016 Tse Lun Bien
> > > + * Copyright (c) 2014 Marco Gittler
> > > + * Copyright (c) 2006-2007 Till Harbaum (Till@Harbaum.org)
> > > + */
> > > +
> > > +#include <linux/kernel.h>
> > > +#include <linux/mfd/ch341.h>
> > > +#include <linux/mfd/core.h>
> > > +#include <linux/module.h>
> > > +#include <linux/slab.h>
> > > +#include <linux/usb.h>
> > > +
> > > +static const struct mfd_cell ch341_devs[] = {
> > > +	{
> > > +		.name = "ch341-gpio",
> > > +	},
> > > +	{
> > > +		.name = "ch341-i2c",
> > > +	},
> > > +};
> > > +
> > > +static int ch341_usb_probe(struct usb_interface *iface,
> > > +			   const struct usb_device_id *usb_id)
> > > +{
> > > +	struct usb_endpoint_descriptor *bulk_out;
> > > +	struct usb_endpoint_descriptor *bulk_in;
> > > +	struct usb_endpoint_descriptor *intr_in;
> > > +	struct ch341_ddata *ddata;
> > > +	int ret;
> > > +
> > > +	ddata = devm_kzalloc(&iface->dev, sizeof(*ddata), GFP_KERNEL);
> > > +	if (!ddata)
> > > +		return -ENOMEM;
> > > +
> > > +	ddata->usb_dev = interface_to_usbdev(iface);
> > > +	mutex_init(&ddata->usb_lock);
> > > +
> > > +	ret = usb_find_common_endpoints(iface->cur_altsetting, &bulk_in,
> > > +					&bulk_out, &intr_in, NULL);
> > > +	if (ret) {
> > > +		dev_err(&iface->dev, "Could not find all endpoints\n");
> > > +		return -ENODEV;
> > > +	}
> > > +
> > > +	ddata->ep_in = bulk_in->bEndpointAddress;
> > > +	ddata->ep_out = bulk_out->bEndpointAddress;
> > > +	ddata->ep_intr = intr_in->bEndpointAddress;
> > > +	ddata->ep_intr_interval = intr_in->bInterval;
> > > +
> > > +	usb_set_intfdata(iface, ddata);
> > > +
> > > +	ret = mfd_add_devices(&iface->dev, PLATFORM_DEVID_AUTO, ch341_devs,
> > > +			      ARRAY_SIZE(ch341_devs), NULL, 0, NULL);
> > > +	if (ret)
> > > +		return dev_err_probe(&iface->dev, ret,
> > > +				     "Failed to register child devices\n");
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static void ch341_usb_disconnect(struct usb_interface *usb_if)
> > > +{
> > > +	mfd_remove_devices(&usb_if->dev);
> > > +}
> > > +
> > > +static const struct usb_device_id ch341_usb_table[] = {
> > > +	{ USB_DEVICE(0x1a86, 0x5512) },
> > > +	{ }
> > > +};
> > > +MODULE_DEVICE_TABLE(usb, ch341_usb_table);
> > > +
> > > +static struct usb_driver ch341_usb_driver = {
> > > +	.name       = "ch341-mfd",
> > > +	.id_table   = ch341_usb_table,
> > > +	.probe      = ch341_usb_probe,
> > > +	.disconnect = ch341_usb_disconnect,
> > > +};
> > > +module_usb_driver(ch341_usb_driver);
> > > +
> > > +MODULE_AUTHOR("Frank Zago <frank@zago.net>");
> > > +MODULE_DESCRIPTION("CH341 USB to I2C/SPI/GPIO adapter");
> > > +MODULE_LICENSE("GPL");
> > > diff --git a/include/linux/mfd/ch341.h b/include/linux/mfd/ch341.h
> > > new file mode 100644
> > > index 000000000000..44f5da0720bd
> > > --- /dev/null
> > > +++ b/include/linux/mfd/ch341.h
> > > @@ -0,0 +1,18 @@
> > > +/* SPDX-License-Identifier: GPL-2.0 */
> > > +/* Definitions for the CH341 driver */
> > > +
> > > +#include <linux/mutex.h>
> > > +#include <linux/types.h>
> > > +
> > > +struct usb_device;
> > > +struct usb_interface;
> > > +
> > > +struct ch341_ddata {
> > > +	struct usb_device *usb_dev;
> > > +	struct mutex usb_lock;
> > > +
> > > +	int ep_in;
> > > +	int ep_out;
> > > +	int ep_intr;
> > > +	u8 ep_intr_interval;
> > > +};
> 
> 
> Looks sane enough, but doesn't actually do any USB data transfers, maybe
> that happens somewhere else...

I expect those to happen in *both* of these:

  static const struct mfd_cell ch341_devs[] = {
	{
		.name = "ch341-gpio",
	},
	{
		.name = "ch341-i2c",
	},
  };

Is that correct Frank?

> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Thanks.

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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