Message-ID: <575857B0.3090504@ti.com>
Date:	Wed, 8 Jun 2016 12:36:48 -0500
From:	"Andrew F. Davis" <afd@...com>
To:	Lee Jones <lee.jones@...aro.org>
CC:	Wolfram Sang <wsa@...-dreams.de>, <linux-i2c@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mfd: sm-usb-dig: Add support for the TI SM-USB-DIG

On 06/08/2016 08:06 AM, Lee Jones wrote:
> On Tue, 31 May 2016, Andrew F. Davis wrote:
> 
>> The TI SM-USB-DIG is a USB to SPI/I2C/1Wire/GPIO adapter.
>> Add MFD core support.
>>
>> Signed-off-by: Andrew F. Davis <afd@...com>
>> ---
>> The SPI, GPIO, and 1Wire drivers are WIP.
>>
>>  drivers/mfd/Kconfig            |   8 +++
>>  drivers/mfd/Makefile           |   2 +
>>  drivers/mfd/sm-usb-dig.c       | 138 +++++++++++++++++++++++++++++++++++++++++
>>  include/linux/mfd/sm-usb-dig.h |  73 ++++++++++++++++++++++
>>  4 files changed, 221 insertions(+)
>>  create mode 100644 drivers/mfd/sm-usb-dig.c
>>  create mode 100644 include/linux/mfd/sm-usb-dig.h
>>
>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>> index 1bcf601..455219a 100644
>> --- a/drivers/mfd/Kconfig
>> +++ b/drivers/mfd/Kconfig
>> @@ -1373,6 +1373,14 @@ config MFD_LM3533
>>  	  additional drivers must be enabled in order to use the LED,
>>  	  backlight or ambient-light-sensor functionality of the device.
>>  
>> +config MFD_SM_USB_DIG
>> +	tristate "Texas Instruments SM-USB-DIG interface adapter"
> 
> If it is decided that MFD is truly the best place for this driver, you
> are still going to need a USB Ack for it.
> 

Okay, will CC for next version.

>> +	select MFD_CORE
>> +	help
>> +	  Support for the TI SM-USB-DIG USB to SPI/I2C/1Wire/GPIO adapter.
>> +	  Additional drivers such as SPI_SM_USB_DIG, I2C_SM_USB_DIG, etc. must
>> +	  be enabled in order to use the functionality of the device.
>> +
>>  config MFD_TIMBERDALE
>>  	tristate "Timberdale FPGA"
>>  	select MFD_CORE
>> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
>> index 42a66e1..376013e 100644
>> --- a/drivers/mfd/Makefile
>> +++ b/drivers/mfd/Makefile
>> @@ -68,6 +68,8 @@ obj-$(CONFIG_MFD_WM8350_I2C)	+= wm8350-i2c.o
>>  wm8994-objs			:= wm8994-core.o wm8994-irq.o wm8994-regmap.o
>>  obj-$(CONFIG_MFD_WM8994)	+= wm8994.o
>>  
>> +obj-$(CONFIG_MFD_SM_USB_DIG)    += sm-usb-dig.o
>> +
>>  obj-$(CONFIG_TPS6105X)		+= tps6105x.o
>>  obj-$(CONFIG_TPS65010)		+= tps65010.o
>>  obj-$(CONFIG_TPS6507X)		+= tps6507x.o
>> diff --git a/drivers/mfd/sm-usb-dig.c b/drivers/mfd/sm-usb-dig.c
>> new file mode 100644
>> index 0000000..cf7ccab
>> --- /dev/null
>> +++ b/drivers/mfd/sm-usb-dig.c
> 
> This should probably be ti-sm-usb-dig.c
> 

There doesn't seem to be a standard of prefixing devices with their
manufacturers name, why would here be any different?

>> @@ -0,0 +1,138 @@
>> +/*
>> + * MFD Core driver for TI SM-USB-DIG
>> + *
>> + * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
>> + *	Andrew F. Davis <afd@...com>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>> + * kind, whether expressed or implied; without even the implied warranty
>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License version 2 for more details.
>> + */
>> +
>> +#include <linux/usb.h>
>> +#include <linux/mfd/core.h>
>> +#include <linux/module.h>
>> +
>> +#include <linux/mfd/sm-usb-dig.h>
> 
> All alphabetical.
> 

ACK

>> +#define USB_VENDOR_ID_TI                0x0451
>> +#define USB_DEVICE_ID_TI_SM_USB_DIG	0x2f90
> 
> TI at the beginning.
> 

ACK

>> +#define SMUSBDIG_USB_TIMEOUT		1000	/* in ms */
> 
> Rename to SMUSBDIG_USB_TIMEOUT_MS
> 

ACK

>> +struct smusbdig_device {
>> +	struct usb_device *usb_dev;
>> +	struct usb_interface *interface;
>> +};
> 
> s/smusbdig/ti_smusbdig/
> 
> ... throughout.
> 

I'm not sure about this, I don't think anyone else will be making one of
these and this only adds a lot of extra characters to a lot of lines.

>> +int smusbdig_xfer(struct smusbdig_device *smusbdig, u8 *buffer, int size)
>> +{
>> +	struct device *dev = &smusbdig->interface->dev;
>> +	int actual_length, ret;
>> +
>> +	if (!smusbdig || !buffer || size <= 0)
>> +		return -EINVAL;
>> +
>> +	ret = usb_interrupt_msg(smusbdig->usb_dev,
>> +				usb_sndctrlpipe(smusbdig->usb_dev, 1),
>> +				buffer, size, &actual_length,
>> +				SMUSBDIG_USB_TIMEOUT);
>> +	if (ret) {
>> +		dev_err(dev, "USB transaction failed\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = usb_interrupt_msg(smusbdig->usb_dev,
>> +				usb_rcvctrlpipe(smusbdig->usb_dev, 1),
>> +				buffer, SMUSBDIG_PACKET_SIZE, &actual_length,
>> +				SMUSBDIG_USB_TIMEOUT);
>> +	if (ret) {
>> +		dev_err(dev, "USB transaction failed\n");
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(smusbdig_xfer);
>> +
>> +static const struct mfd_cell smusbdig_mfd_cells[] = {
>> +	{ .name = "sm-usb-dig-gpio", },
>> +	{ .name = "sm-usb-dig-i2c", },
>> +	{ .name = "sm-usb-dig-spi", },
>> +	{ .name = "sm-usb-dig-w1", },
>> +};
>> +
>> +static int smusbdig_probe(struct usb_interface *interface,
>> +			  const struct usb_device_id *usb_id)
>> +{
>> +	struct usb_host_interface *hostif = interface->cur_altsetting;
>> +	struct device *dev = &interface->dev;
>> +	struct smusbdig_device *smusbdig;
>> +	u8 buffer[SMUSBDIG_PACKET_SIZE];
>> +	int ret;
>> +
>> +	if (hostif->desc.bInterfaceNumber != 0 ||
>> +	    hostif->desc.bNumEndpoints < 2)
>> +		return -ENODEV;
>> +
>> +	smusbdig = devm_kzalloc(dev, sizeof(*smusbdig), GFP_KERNEL);
>> +	if (!smusbdig)
>> +		return -ENOMEM;
>> +
>> +	smusbdig->usb_dev = usb_get_dev(interface_to_usbdev(interface));
>> +	smusbdig->interface = interface;
>> +	usb_set_intfdata(interface, smusbdig);
>> +
>> +	buffer[0] = SMUSBDIG_VERSION;
>> +	ret = smusbdig_xfer(smusbdig, buffer, 1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_info(dev, "TI SM-USB-DIG Version: %d.%02d Found\n",
>> +		 buffer[0], buffer[1]);
>> +
>> +	/* Turn on power supply output */
>> +	buffer[0] = SMUSBDIG_COMMAND;
>> +	buffer[1] = SMUSBDIG_COMMAND_DUTPOWERON;
>> +	ret = smusbdig_xfer(smusbdig, buffer, 2);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_set_drvdata(dev, smusbdig);
>> +	ret = mfd_add_hotplug_devices(dev, smusbdig_mfd_cells,
>> +				      ARRAY_SIZE(smusbdig_mfd_cells));
>> +	if (ret) {
>> +		dev_err(dev, "unable to add MFD devices\n");
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +void smusbdig_disconnect(struct usb_interface *interface)
>> +{
>> +	mfd_remove_devices(&interface->dev);
>> +}
>> +
>> +static const struct usb_device_id smusbdig_id_table[] = {
>> +	{ USB_DEVICE(USB_VENDOR_ID_TI, USB_DEVICE_ID_TI_SM_USB_DIG) },
>> +	{ /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(usb, smusbdig_id_table);
>> +
>> +static struct usb_driver smusbdig_driver = {
>> +	.name = "sm-usb-dig",
>> +	.probe = smusbdig_probe,
>> +	.disconnect = smusbdig_disconnect,
>> +	.id_table = smusbdig_id_table,
>> +};
>> +module_usb_driver(smusbdig_driver);
> 
> This doesn't look like an MFD driver.
> 
> Why aren't you putting this in the USB subsystem?
> 

This is not a USB driver, it just attaches to the USB bus like other
drivers in this subsystem that attach to SPI/I2C/Platform buses, drivers
tend to go into folders based on the functionality they expose, and this
exposes multiple functions, not USB functionality, so MFD makes the most
sense to me.

This device/driver is just like the dln2 and viperboard drivers
currently in the MFD subsystem.

>> +MODULE_AUTHOR("Andrew F. Davis <afd@...com>");
>> +MODULE_DESCRIPTION("Core driver for TI SM-USB-DIG interface adapter");
>> +MODULE_LICENSE("GPL v2");
>> diff --git a/include/linux/mfd/sm-usb-dig.h b/include/linux/mfd/sm-usb-dig.h
>> new file mode 100644
>> index 0000000..1558ff2
>> --- /dev/null
>> +++ b/include/linux/mfd/sm-usb-dig.h
>> @@ -0,0 +1,73 @@
>> +/*
>> + * Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
>> + *	Andrew F. Davis <afd@...com>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
>> + * kind, whether expressed or implied; without even the implied warranty
>> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License version 2 for more details.
>> + */
>> +
>> +#ifndef __LINUX_MFD_SM_USB_DIG_H
>> +#define __LINUX_MFD_SM_USB_DIG_H
>> +
>> +#define SMUSBDIG_PACKET_SIZE    32
>> +/* (packet size - packet header */
>> +#define SMUSBDIG_DATA_SIZE (SMUSBDIG_PACKET_SIZE - 7)
>> +
>> +enum smusbdig_function {
>> +	SMUSBDIG_SPI            = 0x01,
>> +	SMUSBDIG_I2C            = 0x02,
>> +	SMUSBDIG_1W             = 0x03,
>> +	SMUSBDIG_COMMAND        = 0x04,
>> +	SMUSBDIG_VERSION        = 0x07,
>> +};
>> +
>> +enum smusbdig_sub_command {
>> +	SMUSBDIG_COMMAND_DUTPOWERON	= 0x01,
>> +	SMUSBDIG_COMMAND_DUTPOWEROFF	= 0x02,
>> +};
>> +
>> +struct smusbdig_packet {
>> +	u8 function;
>> +	u8 channel;
>> +	u8 edge_polarity;
>> +	u8 num_commands;
>> +	u8 is_command_mask[3];
>> +	u8 data[SMUSBDIG_DATA_SIZE];
>> +} __packed;
>> +
>> +static void smusbdig_packet_add_command(struct smusbdig_packet *packet,
>> +					int command)
>> +{
>> +	int num_commands = packet->num_commands;
>> +	int mask_number = num_commands / 8;
>> +	int mask_bit = num_commands % 8;
>> +
>> +	if (num_commands >= SMUSBDIG_DATA_SIZE)
>> +		return;
>> +
>> +	packet->is_command_mask[mask_number] |= BIT(7 - mask_bit);
>> +	packet->data[num_commands] = command;
>> +	packet->num_commands++;
>> +}
> 
> Inline?
> 

ACK

>> +static void smusbdig_packet_add_data(struct smusbdig_packet *packet, u8 data)
>> +{
>> +	int num_commands = packet->num_commands;
>> +
>> +	if (num_commands >= SMUSBDIG_DATA_SIZE)
>> +		return;
>> +
>> +	packet->data[num_commands] = data;
>> +	packet->num_commands++;
>> +}
> 
> Inline?
> 

ACK

>> +struct smusbdig_device;
>> +int smusbdig_xfer(struct smusbdig_device *smusbdig, u8 *buffer, int size);
>> +
>> +#endif /* __LINUX_MFD_SM_USB_DIG_H */
> 

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