RE: [patch v4 2/2] mfd: Add Mellanox regmap I2C driver

[Vadim Pasternak <vadimp@mellanox.com>]

> -----Original Message-----
> From: Lee Jones [mailto:lee.jones@linaro.org]
> Sent: Tuesday, September 05, 2017 10:36 AM
> To: Vadim Pasternak <vadimp@mellanox.com>
> Cc: robh+dt@kernel.org; pavel@ucw.cz; devicetree@vger.kernel.org;
> j.anaszewski@samsung.com; rpurdie@rpsys.net; linux-leds@vger.kernel.org;
> jiri@resnulli.us; gregkh@linuxfoundation.org; platform-driver-
> x86@vger.kernel.org
> Subject: Re: [patch v4 2/2] mfd: Add Mellanox regmap I2C driver
> 
> On Tue, 29 Aug 2017, Vadim Pasternak wrote:
> 
> > This patch adds I2C regmap driver for Mellanox BMC cards with the
> > programmable devices attached to I2C interface. It allows support for
> > CPLD devices with one and two bytes address space.
> >
> > Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
> > Acked-by: Pavel Machek <pavel@ucw.cz>
> > ---
> >  MAINTAINERS              |   1 +
> >  drivers/mfd/Kconfig      |  13 ++++
> >  drivers/mfd/Makefile     |   1 +
> >  drivers/mfd/mlxreg-i2c.c | 183
> > +++++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 198 insertions(+)
> >  create mode 100644 drivers/mfd/mlxreg-i2c.c
> 
> I don't know what this is, but it is not an MFD driver.  Please find somewhere
> more appropriate to locate it.  MFD is not a dumping ground for drivers
> which do not fit anywhere else.

Hi Lee,

As according your previous notes I am splitting hotplug driver  and moving it to new 
folder drivers/platform/mellanox/, possibly it would be the best place to relocate it
there. I also intend to have in the future small drivers mlxreg-spi, mlxreg-mmio and
maybe it would be correct to to use these new folder for all of them?

Thanks,
Vadim.

> 
> > diff --git a/MAINTAINERS b/MAINTAINERS index bcb7f45..86a5f8f 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -8299,6 +8299,7 @@ M:	Vadim Pasternak <vadimp@mellanox.com>
> >  S:	Supported
> >  F:	Documentation/devicetree/bindings/mfd/mellanox,mlxreg-core
> >  F:	drivers/mfd/mlxreg-core.c
> > +F:	drivers/mfd/mlxreg-i2c.c
> >  F:	include/linux/platform_data/mlxreg.h
> >
> >  MELLANOX ETHERNET DRIVER (mlx4_en)
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig index
> > fa1562f..453afcb 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -1709,6 +1709,19 @@ config MFD_MLXREG_CORE
> >  	  This driver can also be built as a module. If so the module
> >  	  will be called mlxreg-core.
> >
> > +config MFD_MLXREG_I2C
> > +	bool "Mellanox programmable device with I2C interface"
> > +	depends on I2C && REGMAP_I2C
> > +	depends on MFD_MLXREG_CORE
> > +	help
> > +	  Support for the Mellanox BMC card with hardware control by a
> > +	  programmable device. This option enables core support for the
> > +	  programmable devices with I2C interface. It allows support for
> > +	  the devices with address space 1 and 2 bytes.
> > +
> > +	  This driver can also be built as a module. If so the module
> > +	  will be called mlxreg-i2c.
> > +
> >  menu "Multimedia Capabilities Port drivers"
> >  	depends on ARCH_SA1100
> >
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile index
> > 9661ee2..b76c5b2 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -222,3 +222,4 @@ obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-
> gpadc.o
> >  obj-$(CONFIG_MFD_STM32_TIMERS) 	+= stm32-timers.o
> >  obj-$(CONFIG_MFD_MXS_LRADC)     += mxs-lradc.o
> >  obj-$(CONFIG_MFD_MLXREG_CORE)	+= mlxreg-core.o
> > +obj-$(CONFIG_MFD_MLXREG_I2C)	+= mlxreg-i2c.o
> > diff --git a/drivers/mfd/mlxreg-i2c.c b/drivers/mfd/mlxreg-i2c.c new
> > file mode 100644 index 0000000..04823b5
> > --- /dev/null
> > +++ b/drivers/mfd/mlxreg-i2c.c
> > @@ -0,0 +1,183 @@
> > +/*
> > + * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
> > + * Copyright (c) 2017 Vadim Pasternak <vadimp@mellanox.com>
> > + *
> > + * Redistribution and use in source and binary forms, with or without
> > + * modification, are permitted provided that the following conditions are
> met:
> > + *
> > + * 1. Redistributions of source code must retain the above copyright
> > + *    notice, this list of conditions and the following disclaimer.
> > + * 2. Redistributions in binary form must reproduce the above copyright
> > + *    notice, this list of conditions and the following disclaimer in the
> > + *    documentation and/or other materials provided with the
> distribution.
> > + * 3. Neither the names of the copyright holders nor the names of its
> > + *    contributors may be used to endorse or promote products derived
> from
> > + *    this software without specific prior written permission.
> > + *
> > + * Alternatively, this software may be distributed under the terms of
> > +the
> > + * GNU General Public License ("GPL") version 2 as published by the
> > +Free
> > + * Software Foundation.
> > + *
> > + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
> CONTRIBUTORS "AS IS"
> > + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> LIMITED
> > +TO, THE
> > + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
> PARTICULAR
> > +PURPOSE
> > + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
> > +CONTRIBUTORS BE
> > + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
> > +OR
> > + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
> PROCUREMENT
> > +OF
> > + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
> > +BUSINESS
> > + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
> > +WHETHER IN
> > + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
> > +OTHERWISE)
> > + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
> > +ADVISED OF THE
> > + * POSSIBILITY OF SUCH DAMAGE.
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/i2c.h>
> > +#include <linux/module.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +
> > +/**
> > + * enum mlxreg_i2c_type - driver flavours:
> > + *
> > + * @MLXREG_8BIT: type for I2C CPLD control with 1 byte address space;
> > + * @MLXREG_16BIT: type for I2C CPLD control with 2 bytes address
> > +space;  */ enum mlxreg_i2c_type {
> > +	MLXREG_8BIT,
> > +	MLXREG_16BIT,
> > +};
> > +
> > +/**
> > + * Configuration for the register map of a device with 1 byte address
> space.
> > + */
> > +static const struct regmap_config mlxreg_i2c_regmap8_conf = {
> > +	.reg_bits = 8,
> > +	.val_bits = 8,
> > +	.max_register = 255,
> > +};
> > +
> > +/**
> > + * Configuration for the register map of a device with 2 bytes address
> space.
> > + */
> > +static const struct regmap_config mlxreg_i2c_regmap16_conf = {
> > +	.reg_bits = 16,
> > +	.val_bits = 16,
> > +	.max_register = 1023,
> > +};
> > +
> > +static struct resource mlxreg_i2c_resources[] = {
> > +	[0] = DEFINE_RES_IRQ_NAMED(-1, "mlxcpld-ctrl-2c"), };
> > +
> > +static int
> > +mlxreg_i2c_probe(struct i2c_client *client, const struct
> > +i2c_device_id *id) {
> > +	struct device_node *child, *np = client->dev.of_node;
> > +	struct platform_device *pdev;
> > +	struct i2c_adapter *adapter;
> > +	struct regmap *regmap;
> > +	int err = 0;
> > +
> > +	if (!np)
> > +		return -ENODEV;
> > +
> > +	if (!of_device_is_compatible(np, "mellanox,mlxreg-i2c"))
> > +		return -ENODEV;
> > +
> > +	child = of_parse_phandle(np, "deferred", 0);
> > +	if (child) {
> > +		adapter = of_find_i2c_adapter_by_node(child);
> > +		of_node_put(child);
> > +		if (!adapter)
> > +			return -EPROBE_DEFER;
> > +	}
> > +
> > +	if (!i2c_check_functionality(client->adapter,
> > +				     I2C_FUNC_SMBUS_BYTE_DATA |
> > +				     I2C_FUNC_SMBUS_WORD_DATA |
> > +				     I2C_FUNC_SMBUS_I2C_BLOCK))
> > +		return -ENODEV;
> > +
> > +	switch (id->driver_data) {
> > +	case MLXREG_8BIT:
> > +		regmap = devm_regmap_init_i2c(client,
> > +					      &mlxreg_i2c_regmap8_conf);
> > +		break;
> > +	case MLXREG_16BIT:
> > +		regmap = devm_regmap_init_i2c(client,
> > +					      &mlxreg_i2c_regmap16_conf);
> > +		break;
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (IS_ERR(regmap))
> > +		return PTR_ERR(regmap);
> > +
> > +	pdev = platform_device_alloc("mlxreg-core", (client->adapter->nr <<
> 8)
> > +				     | client->addr);
> > +	if (!pdev)
> > +		return -ENOMEM;
> > +
> > +	i2c_set_clientdata(client, pdev);
> > +	pdev->dev.parent = &client->dev;
> > +	pdev->dev.of_node = client->dev.of_node;
> > +	pdev->dev.platform_data = regmap;
> > +
> > +	if (client->irq) {
> > +		mlxreg_i2c_resources[0].start = client->irq;
> > +		err = platform_device_add_resources(pdev,
> > +				mlxreg_i2c_resources,
> > +				ARRAY_SIZE(mlxreg_i2c_resources));
> > +	}
> > +
> > +	err = err ? err : platform_device_add(pdev);
> > +
> > +	if (err)
> > +		platform_device_put(pdev);
> > +
> > +	return err;
> > +}
> > +
> > +static int mlxreg_i2c_remove(struct i2c_client *client) {
> > +	struct platform_device *pdev = i2c_get_clientdata(client);
> > +
> > +	platform_device_unregister(pdev);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct i2c_device_id mlxreg_i2c_id[] = {
> > +	{ "mlxreg-i2c", MLXREG_8BIT },
> > +	{ "mlxreg-i2c-16", MLXREG_16BIT },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(i2c, mlxreg_i2c_id);
> > +
> > +static const struct of_device_id mlxreg_i2c_dt_match[] = {
> > +	{ .compatible = "mellanox,mlxreg-i2c" },
> > +	{ .compatible = "mellanox,mlxreg-i2c-16" },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, mlxreg_i2c_dt_match);
> > +
> > +static struct i2c_driver mlxreg_i2c_driver = {
> > +	.class = I2C_CLASS_HWMON,
> > +	.driver = {
> > +	    .name = "mlxreg-i2c",
> > +	    .of_match_table = of_match_ptr(mlxreg_i2c_dt_match),
> > +	},
> > +	.probe = mlxreg_i2c_probe,
> > +	.remove = mlxreg_i2c_remove,
> > +	.id_table = mlxreg_i2c_id,
> > +};
> > +
> > +module_i2c_driver(mlxreg_i2c_driver);
> > +
> > +MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
> > +MODULE_DESCRIPTION("Mellanox CPLD control I2C driver");
> > +MODULE_LICENSE("Dual BSD/GPL"); MODULE_ALIAS("mlxreg-i2c");
> 
> --
> Lee Jones
> Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source
> software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog