diff mbox series

[2/6] mfd: Initial commit of sy7636a

Message ID 20210117042539.1609-2-alistair@alistair23.me
State New
Headers show
Series None | expand

Commit Message

Alistair Jan. 17, 2021, 4:25 a.m. UTC
Initial support for the Silergy SY7636A Power Management chip
driver.

Signed-off-by: Alistair Francis <alistair@alistair23.me>
---
 drivers/mfd/Kconfig         |  10 ++
 drivers/mfd/Makefile        |   2 +
 drivers/mfd/sy7636a.c       | 252 ++++++++++++++++++++++++++++++++++++
 include/linux/mfd/sy7636a.h |  50 +++++++
 4 files changed, 314 insertions(+)
 create mode 100644 drivers/mfd/sy7636a.c
 create mode 100644 include/linux/mfd/sy7636a.h

Comments

Lee Jones Feb. 4, 2021, 10:31 a.m. UTC | #1
On Sat, 16 Jan 2021, Alistair Francis wrote:

> Initial support for the Silergy SY7636A Power Management chip

> driver.


Please remove "driver", as this is not support for the driver, it *is*
the driver which supports the chip.

> Signed-off-by: Alistair Francis <alistair@alistair23.me>

> ---

>  drivers/mfd/Kconfig         |  10 ++

>  drivers/mfd/Makefile        |   2 +

>  drivers/mfd/sy7636a.c       | 252 ++++++++++++++++++++++++++++++++++++

>  include/linux/mfd/sy7636a.h |  50 +++++++

>  4 files changed, 314 insertions(+)

>  create mode 100644 drivers/mfd/sy7636a.c

>  create mode 100644 include/linux/mfd/sy7636a.h

> 

> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig

> index bdfce7b15621..c8c62d92433c 100644

> --- a/drivers/mfd/Kconfig

> +++ b/drivers/mfd/Kconfig

> @@ -1360,6 +1360,16 @@ config MFD_SYSCON

>  	  Select this option to enable accessing system control registers

>  	  via regmap.

>  

> +config MFD_SY7636A

> +	tristate "Silergy SY7636A Power Management chip driver"


Again, please remove the word "driver" here.

> +	select MFD_CORE

> +	select REGMAP_I2C

> +	select REGMAP_IRQ

> +	depends on I2C=y

> +	help

> +	  Select this option to enable support for the Silergy SY7636A

> +	  Power Management chip driver.


And again.

>  config MFD_DAVINCI_VOICECODEC

>  	tristate

>  	select MFD_CORE

> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile

> index 14fdb188af02..1fa1e635f506 100644

> --- a/drivers/mfd/Makefile

> +++ b/drivers/mfd/Makefile

> @@ -265,6 +265,8 @@ obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o

>  obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o

>  obj-$(CONFIG_MFD_KHADAS_MCU) 	+= khadas-mcu.o

>  

> +obj-$(CONFIG_MFD_SY7636A)	+= sy7636a.o

> +


Why does this have to be segregated?

>  obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o

>  obj-$(CONFIG_MFD_SIMPLE_MFD_I2C)	+= simple-mfd-i2c.o

>  obj-$(CONFIG_MFD_INTEL_M10_BMC)   += intel-m10-bmc.o

> diff --git a/drivers/mfd/sy7636a.c b/drivers/mfd/sy7636a.c

> new file mode 100644

> index 000000000000..39aac965d854

> --- /dev/null

> +++ b/drivers/mfd/sy7636a.c

> @@ -0,0 +1,252 @@

> +// SPDX-License-Identifier: GPL-2.0+

> +/*

> + * MFD driver for SY7636A chip


"Parent driver".

> + * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/


This is quite out of date.  Please update.

> + * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>

> + *

> + * This program is free software; you can redistribute it and/or

> + * modify it under the terms of the GNU General Public License as

> + * published by the Free Software Foundation version 2.

> + *

> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any

> + * kind, whether express or implied; without even the implied warranty

> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

> + * GNU General Public License for more details.


This test is replaced by the SPDX header above.

> + * Based on the lp87565 driver by Keerthy <j-keerthy@ti.com>

> + */

> +

> +#include <linux/interrupt.h>

> +#include <linux/mfd/core.h>

> +#include <linux/module.h>

> +#include <linux/of_device.h>

> +#include <linux/regmap.h>

> +#include <linux/sysfs.h>

> +

> +#include <linux/mfd/sy7636a.h>

> +

> +static const struct regmap_config sy7636a_regmap_config = {

> +	.reg_bits = 8,

> +	.val_bits = 8,

> +};

> +

> +static const struct mfd_cell sy7636a_cells[] = {

> +	{ .name = "sy7636a-regulator", },

> +	{ .name = "sy7636a-temperature", },

> +	{ .name = "sy7636a-thermal", },

> +};

> +

> +static const struct of_device_id of_sy7636a_match_table[] = {

> +	{ .compatible = "silergy,sy7636a", },

> +	{}

> +};

> +MODULE_DEVICE_TABLE(of, of_sy7636a_match_table);


Please move this to where it is used i.e. at the bottom of the file.

> +static const char * const states[] = {

> +	"no fault event",

> +	"UVP at VP rail",

> +	"UVP at VN rail",

> +	"UVP at VPOS rail",

> +	"UVP at VNEG rail",

> +	"UVP at VDDH rail",

> +	"UVP at VEE rail",

> +	"SCP at VP rail",

> +	"SCP at VN rail",

> +	"SCP at VPOS rail",

> +	"SCP at VNEG rail",

> +	"SCP at VDDH rail",

> +	"SCP at VEE rail",

> +	"SCP at V COM rail",

> +	"UVLO",

> +	"Thermal shutdown",

> +};

> +

> +int get_vcom_voltage_mv(struct regmap *regmap)

> +{

> +	int ret;

> +	unsigned int val, val_h;

> +

> +	ret = regmap_read(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, &val);

> +	if (ret)

> +		return ret;

> +

> +	ret = regmap_read(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, &val_h);

> +	if (ret)

> +		return ret;

> +

> +	val |= (val_h << 8);


Please define the shifts and masks.

> +	return (val & 0x1FF) * 10;


What's 10?

> +}

> +

> +int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom)

> +{

> +	int ret;

> +	unsigned int val;

> +

> +	if (vcom < 0 || vcom > 5000)


Please define min/max values.

> +		return -EINVAL;

> +

> +	val = (unsigned int)(vcom / 10) & 0x1ff;


As above.

> +	ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, val);

> +	if (ret)

> +		return ret;

> +

> +	ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, val >> 8);

> +	if (ret)

> +		return ret;

> +

> +	return 0;

> +}


Who calls these?

> +static ssize_t state_show(struct device *dev, struct device_attribute *attr,

> +		char *buf)

> +{

> +	int ret;

> +	unsigned int val;

> +	struct sy7636a *sy7636a = dev_get_drvdata(dev);

> +

> +	ret = regmap_read(sy7636a->regmap, SY7636A_REG_FAULT_FLAG, &val);

> +	if (ret) {

> +		dev_err(sy7636a->dev, "Failed to read from device\n");

> +		return ret;

> +	}

> +

> +	val = val >> 1;


Why 1?

> +	if (val >= ARRAY_SIZE(states)) {

> +		dev_err(sy7636a->dev, "Unexpected value read from device: %u\n", val);

> +		return -EINVAL;

> +	}

> +

> +	return snprintf(buf, PAGE_SIZE, "%s\n", states[val]);

> +}

> +static DEVICE_ATTR(state, 0444, state_show, NULL);


You need to document new sysfs entries.

> +static ssize_t power_good_show(struct device *dev, struct device_attribute *attr,

> +		char *buf)

> +{

> +	int ret;

> +	unsigned int val;

> +	struct sy7636a *sy7636a = dev_get_drvdata(dev);

> +

> +	ret = regmap_read(sy7636a->regmap, SY7636A_REG_FAULT_FLAG, &val);

> +	if (ret) {

> +		dev_err(sy7636a->dev, "Failed to read from device\n");

> +		return ret;

> +	}

> +

> +	val &= 0x01;

> +

> +	return snprintf(buf, PAGE_SIZE, "%s\n", val ? "ON" : "OFF");


Doesn't 0 just mean "no fault event"?

> +}

> +static DEVICE_ATTR(power_good, 0444, power_good_show, NULL);

> +

> +static ssize_t vcom_show(struct device *dev, struct device_attribute *attr,

> +		char *buf)

> +{

> +	int ret;

> +	struct sy7636a *sy7636a = dev_get_drvdata(dev);

> +

> +	ret = get_vcom_voltage_mv(sy7636a->regmap);

> +	if (ret < 0)

> +		return ret;

> +

> +	return snprintf(buf, PAGE_SIZE, "%d\n", -ret);

> +}

> +


Remove this line please.

> +static ssize_t vcom_store(struct device *dev,

> +		struct device_attribute *attr, const char *buf, size_t count)

> +{

> +	int ret;

> +	int vcom;

> +	struct sy7636a *sy7636a = dev_get_drvdata(dev);

> +

> +	ret = kstrtoint(buf, 0, &vcom);

> +	if (ret)

> +		return ret;

> +

> +	if (vcom > 0 || vcom < -5000)

> +		return -EINVAL;

> +

> +	ret = set_vcom_voltage_mv(sy7636a->regmap, (unsigned int)(-vcom));

> +	if (ret)

> +		return ret;

> +

> +	return count;

> +}

> +static DEVICE_ATTR(vcom, 0644, vcom_show, vcom_store);

> +

> +static struct attribute *sy7636a_sysfs_attrs[] = {

> +	&dev_attr_state.attr,

> +	&dev_attr_power_good.attr,

> +	&dev_attr_vcom.attr,

> +	NULL,

> +};


These all look like power options?  Do they really belong here?

> +static const struct attribute_group sy7636a_sysfs_attr_group = {

> +	.attrs = sy7636a_sysfs_attrs,

> +};

> +

> +static int sy7636a_probe(struct i2c_client *client,

> +			 const struct i2c_device_id *ids)

> +{

> +	struct sy7636a *sy7636a;

> +	int ret;

> +

> +	sy7636a = devm_kzalloc(&client->dev, sizeof(struct sy7636a), GFP_KERNEL);


sizeof(*sy7636a)

> +	if (sy7636a == NULL)


if (!sy7636a)

> +		return -ENOMEM;

> +

> +	sy7636a->dev = &client->dev;

> +

> +	sy7636a->regmap = devm_regmap_init_i2c(client, &sy7636a_regmap_config);

> +	if (IS_ERR(sy7636a->regmap)) {

> +		ret = PTR_ERR(sy7636a->regmap);

> +		dev_err(sy7636a->dev,

> +			"Failed to initialize register map: %d\n", ret);

> +		return ret;

> +	}

> +

> +	i2c_set_clientdata(client, sy7636a);

> +

> +	ret = sysfs_create_group(&client->dev.kobj, &sy7636a_sysfs_attr_group);

> +	if (ret) {

> +		dev_err(sy7636a->dev, "Failed to create sysfs attributes\n");

> +		return ret;

> +	}

> +

> +	ret = devm_mfd_add_devices(sy7636a->dev, PLATFORM_DEVID_AUTO,

> +					sy7636a_cells, ARRAY_SIZE(sy7636a_cells),

> +					NULL, 0, NULL);

> +	if (ret) {

> +		dev_err(sy7636a->dev, "Failed to add mfd devices\n");


"Failed to add child devices"

> +		sysfs_remove_group(&client->dev.kobj, &sy7636a_sysfs_attr_group);

> +		return ret;

> +	}

> +

> +	return 0;

> +}

> +

> +static const struct i2c_device_id sy7636a_id_table[] = {

> +	{ "sy7636a", 0 },

> +	{ },

> +};

> +MODULE_DEVICE_TABLE(i2c, sy7636a_id_table);


If you use .probe2, you can omit this table.

> +static struct i2c_driver sy7636a_driver = {

> +	.driver	= {

> +		.name	= "sy7636a",

> +		.of_match_table = of_sy7636a_match_table,

> +	},

> +	.probe = sy7636a_probe,

> +	.id_table = sy7636a_id_table,

> +};

> +module_i2c_driver(sy7636a_driver);

> +

> +MODULE_AUTHOR("Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>");

> +MODULE_DESCRIPTION("Silergy SY7636A Multi-Function Device Driver");


s/Multi-Function Device Driver/Power Management Chip/

> +MODULE_LICENSE("GPL v2");

> diff --git a/include/linux/mfd/sy7636a.h b/include/linux/mfd/sy7636a.h

> new file mode 100644

> index 000000000000..642789c4d0a9

> --- /dev/null

> +++ b/include/linux/mfd/sy7636a.h

> @@ -0,0 +1,50 @@

> +/* SPDX-License-Identifier: GPL-2.0-only */

> +/*

> + * Functions to access SY3686A power management chip.

> + *

> + * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/

> + *

> + * This program is free software; you can redistribute it and/or

> + * modify it under the terms of the GNU General Public License as

> + * published by the Free Software Foundation version 2.

> + *

> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any

> + * kind, whether express or implied; without even the implied warranty

> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

> + * GNU General Public License for more details.

> + */


Same issues as mentioned above.

> +#ifndef __LINUX_MFD_SY7636A_H

> +#define __LINUX_MFD_SY7636A_H


Just MFD is fine.

> +#include <linux/i2c.h>

> +#include <linux/regulator/driver.h>

> +#include <linux/regulator/machine.h>

> +#include <linux/regmap.h>


Alphabetical.

> +#define SY7636A_REG_OPERATION_MODE_CRL 0x00

> +#define SY7636A_OPERATION_MODE_CRL_VCOMCTL (1 << 6)

> +#define SY7636A_OPERATION_MODE_CRL_ONOFF (1 << 7)

> +#define SY7636A_REG_VCOM_ADJUST_CTRL_L 0x01

> +#define SY7636A_REG_VCOM_ADJUST_CTRL_H 0x02

> +#define SY7636A_REG_VCOM_ADJUST_CTRL_MASK 0x01ff

> +#define SY7636A_REG_VLDO_VOLTAGE_ADJULST_CTRL 0x03

> +#define SY7636A_REG_POWER_ON_DELAY_TIME 0x06

> +#define SY7636A_REG_FAULT_FLAG 0x07

> +#define SY7636A_FAULT_FLAG_PG (1 << 0)

> +#define SY7636A_REG_TERMISTOR_READOUT 0x08


Tab out the values please.

Use BIT()

> +#define SY7636A_REG_MAX 0x08

> +

> +struct sy7636a {

> +	struct device *dev;

> +	struct regmap *regmap;

> +	unsigned int vcom;


Where is this used?

> +	struct gpio_desc *pgood_gpio;


Where is this used?

> +	struct mutex reglock;


Where is this used?

> +};

> +

> +int get_vcom_voltage_mv(struct regmap *regmap);

> +int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom);


What calls these?

> +#endif /* __LINUX_MFD_SY7636A_H */


-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
Alistair Francis March 21, 2021, 2:18 a.m. UTC | #2
On Thu, Feb 4, 2021 at 5:31 AM Lee Jones <lee.jones@linaro.org> wrote:
>

> On Sat, 16 Jan 2021, Alistair Francis wrote:

>

> > Initial support for the Silergy SY7636A Power Management chip

> > driver.

>

> Please remove "driver", as this is not support for the driver, it *is*

> the driver which supports the chip.


Sorry for the long delay here.

I have addressed your comments.

>

> > Signed-off-by: Alistair Francis <alistair@alistair23.me>

> > ---

> >  drivers/mfd/Kconfig         |  10 ++

> >  drivers/mfd/Makefile        |   2 +

> >  drivers/mfd/sy7636a.c       | 252 ++++++++++++++++++++++++++++++++++++

> >  include/linux/mfd/sy7636a.h |  50 +++++++

> >  4 files changed, 314 insertions(+)

> >  create mode 100644 drivers/mfd/sy7636a.c

> >  create mode 100644 include/linux/mfd/sy7636a.h

> >

> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig

> > index bdfce7b15621..c8c62d92433c 100644

> > --- a/drivers/mfd/Kconfig

> > +++ b/drivers/mfd/Kconfig

> > @@ -1360,6 +1360,16 @@ config MFD_SYSCON

> >         Select this option to enable accessing system control registers

> >         via regmap.

> >

> > +config MFD_SY7636A

> > +     tristate "Silergy SY7636A Power Management chip driver"

>

> Again, please remove the word "driver" here.

>

> > +     select MFD_CORE

> > +     select REGMAP_I2C

> > +     select REGMAP_IRQ

> > +     depends on I2C=y

> > +     help

> > +       Select this option to enable support for the Silergy SY7636A

> > +       Power Management chip driver.

>

> And again.


I removed "driver" from all of these.

>

> >  config MFD_DAVINCI_VOICECODEC

> >       tristate

> >       select MFD_CORE

> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile

> > index 14fdb188af02..1fa1e635f506 100644

> > --- a/drivers/mfd/Makefile

> > +++ b/drivers/mfd/Makefile

> > @@ -265,6 +265,8 @@ obj-$(CONFIG_MFD_ROHM_BD718XX)    += rohm-bd718x7.o

> >  obj-$(CONFIG_MFD_STMFX)      += stmfx.o

> >  obj-$(CONFIG_MFD_KHADAS_MCU)         += khadas-mcu.o

> >

> > +obj-$(CONFIG_MFD_SY7636A)    += sy7636a.o

> > +

>

> Why does this have to be segregated?


Fixed

>

> >  obj-$(CONFIG_SGI_MFD_IOC3)   += ioc3.o

> >  obj-$(CONFIG_MFD_SIMPLE_MFD_I2C)     += simple-mfd-i2c.o

> >  obj-$(CONFIG_MFD_INTEL_M10_BMC)   += intel-m10-bmc.o

> > diff --git a/drivers/mfd/sy7636a.c b/drivers/mfd/sy7636a.c

> > new file mode 100644

> > index 000000000000..39aac965d854

> > --- /dev/null

> > +++ b/drivers/mfd/sy7636a.c

> > @@ -0,0 +1,252 @@

> > +// SPDX-License-Identifier: GPL-2.0+

> > +/*

> > + * MFD driver for SY7636A chip

>

> "Parent driver".

>

> > + * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/

>

> This is quite out of date.  Please update.


I don't own this copyright, so I would rather not change it.

>

> > + * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>

> > + *

> > + * This program is free software; you can redistribute it and/or

> > + * modify it under the terms of the GNU General Public License as

> > + * published by the Free Software Foundation version 2.

> > + *

> > + * This program is distributed "as is" WITHOUT ANY WARRANTY of any

> > + * kind, whether express or implied; without even the implied warranty

> > + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

> > + * GNU General Public License for more details.

>

> This test is replaced by the SPDX header above.


Removed.

>

> > + * Based on the lp87565 driver by Keerthy <j-keerthy@ti.com>

> > + */

> > +

> > +#include <linux/interrupt.h>

> > +#include <linux/mfd/core.h>

> > +#include <linux/module.h>

> > +#include <linux/of_device.h>

> > +#include <linux/regmap.h>

> > +#include <linux/sysfs.h>

> > +

> > +#include <linux/mfd/sy7636a.h>

> > +

> > +static const struct regmap_config sy7636a_regmap_config = {

> > +     .reg_bits = 8,

> > +     .val_bits = 8,

> > +};

> > +

> > +static const struct mfd_cell sy7636a_cells[] = {

> > +     { .name = "sy7636a-regulator", },

> > +     { .name = "sy7636a-temperature", },

> > +     { .name = "sy7636a-thermal", },

> > +};

> > +

> > +static const struct of_device_id of_sy7636a_match_table[] = {

> > +     { .compatible = "silergy,sy7636a", },

> > +     {}

> > +};

> > +MODULE_DEVICE_TABLE(of, of_sy7636a_match_table);

>

> Please move this to where it is used i.e. at the bottom of the file.


Done.

>

> > +static const char * const states[] = {

> > +     "no fault event",

> > +     "UVP at VP rail",

> > +     "UVP at VN rail",

> > +     "UVP at VPOS rail",

> > +     "UVP at VNEG rail",

> > +     "UVP at VDDH rail",

> > +     "UVP at VEE rail",

> > +     "SCP at VP rail",

> > +     "SCP at VN rail",

> > +     "SCP at VPOS rail",

> > +     "SCP at VNEG rail",

> > +     "SCP at VDDH rail",

> > +     "SCP at VEE rail",

> > +     "SCP at V COM rail",

> > +     "UVLO",

> > +     "Thermal shutdown",

> > +};

> > +

> > +int get_vcom_voltage_mv(struct regmap *regmap)

> > +{

> > +     int ret;

> > +     unsigned int val, val_h;

> > +

> > +     ret = regmap_read(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, &val);

> > +     if (ret)

> > +             return ret;

> > +

> > +     ret = regmap_read(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, &val_h);

> > +     if (ret)

> > +             return ret;

> > +

> > +     val |= (val_h << 8);

>

> Please define the shifts and masks.

>

> > +     return (val & 0x1FF) * 10;

>

> What's 10?

>

> > +}

> > +

> > +int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom)

> > +{

> > +     int ret;

> > +     unsigned int val;

> > +

> > +     if (vcom < 0 || vcom > 5000)

>

> Please define min/max values.

>

> > +             return -EINVAL;

> > +

> > +     val = (unsigned int)(vcom / 10) & 0x1ff;

>

> As above.


I have used defines for all of these.

>

> > +     ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, val);

> > +     if (ret)

> > +             return ret;

> > +

> > +     ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, val >> 8);

> > +     if (ret)

> > +             return ret;

> > +

> > +     return 0;

> > +}

>

> Who calls these?


They sysfs store and show functions.

>

> > +static ssize_t state_show(struct device *dev, struct device_attribute *attr,

> > +             char *buf)

> > +{

> > +     int ret;

> > +     unsigned int val;

> > +     struct sy7636a *sy7636a = dev_get_drvdata(dev);

> > +

> > +     ret = regmap_read(sy7636a->regmap, SY7636A_REG_FAULT_FLAG, &val);

> > +     if (ret) {

> > +             dev_err(sy7636a->dev, "Failed to read from device\n");

> > +             return ret;

> > +     }

> > +

> > +     val = val >> 1;

>

> Why 1?


I used a define here to make it clearer

>

> > +     if (val >= ARRAY_SIZE(states)) {

> > +             dev_err(sy7636a->dev, "Unexpected value read from device: %u\n", val);

> > +             return -EINVAL;

> > +     }

> > +

> > +     return snprintf(buf, PAGE_SIZE, "%s\n", states[val]);

> > +}

> > +static DEVICE_ATTR(state, 0444, state_show, NULL);

>

> You need to document new sysfs entries.


I'm not sure how to document this. Do you mind pointing out an example
I can use?

>

> > +static ssize_t power_good_show(struct device *dev, struct device_attribute *attr,

> > +             char *buf)

> > +{

> > +     int ret;

> > +     unsigned int val;

> > +     struct sy7636a *sy7636a = dev_get_drvdata(dev);

> > +

> > +     ret = regmap_read(sy7636a->regmap, SY7636A_REG_FAULT_FLAG, &val);

> > +     if (ret) {

> > +             dev_err(sy7636a->dev, "Failed to read from device\n");

> > +             return ret;

> > +     }

> > +

> > +     val &= 0x01;

> > +

> > +     return snprintf(buf, PAGE_SIZE, "%s\n", val ? "ON" : "OFF");

>

> Doesn't 0 just mean "no fault event"?


The LSB is reserved, so we don't clear that.

>

> > +}

> > +static DEVICE_ATTR(power_good, 0444, power_good_show, NULL);

> > +

> > +static ssize_t vcom_show(struct device *dev, struct device_attribute *attr,

> > +             char *buf)

> > +{

> > +     int ret;

> > +     struct sy7636a *sy7636a = dev_get_drvdata(dev);

> > +

> > +     ret = get_vcom_voltage_mv(sy7636a->regmap);

> > +     if (ret < 0)

> > +             return ret;

> > +

> > +     return snprintf(buf, PAGE_SIZE, "%d\n", -ret);

> > +}

> > +

>

> Remove this line please.

>

> > +static ssize_t vcom_store(struct device *dev,

> > +             struct device_attribute *attr, const char *buf, size_t count)

> > +{

> > +     int ret;

> > +     int vcom;

> > +     struct sy7636a *sy7636a = dev_get_drvdata(dev);

> > +

> > +     ret = kstrtoint(buf, 0, &vcom);

> > +     if (ret)

> > +             return ret;

> > +

> > +     if (vcom > 0 || vcom < -5000)

> > +             return -EINVAL;

> > +

> > +     ret = set_vcom_voltage_mv(sy7636a->regmap, (unsigned int)(-vcom));

> > +     if (ret)

> > +             return ret;

> > +

> > +     return count;

> > +}

> > +static DEVICE_ATTR(vcom, 0644, vcom_show, vcom_store);

> > +

> > +static struct attribute *sy7636a_sysfs_attrs[] = {

> > +     &dev_attr_state.attr,

> > +     &dev_attr_power_good.attr,

> > +     &dev_attr_vcom.attr,

> > +     NULL,

> > +};

>

> These all look like power options?  Do they really belong here?


From what I can tell I think they do. Let me know if you don't think so.

>

> > +static const struct attribute_group sy7636a_sysfs_attr_group = {

> > +     .attrs = sy7636a_sysfs_attrs,

> > +};

> > +

> > +static int sy7636a_probe(struct i2c_client *client,

> > +                      const struct i2c_device_id *ids)

> > +{

> > +     struct sy7636a *sy7636a;

> > +     int ret;

> > +

> > +     sy7636a = devm_kzalloc(&client->dev, sizeof(struct sy7636a), GFP_KERNEL);

>

> sizeof(*sy7636a)

>

> > +     if (sy7636a == NULL)

>

> if (!sy7636a)

>

> > +             return -ENOMEM;

> > +

> > +     sy7636a->dev = &client->dev;

> > +

> > +     sy7636a->regmap = devm_regmap_init_i2c(client, &sy7636a_regmap_config);

> > +     if (IS_ERR(sy7636a->regmap)) {

> > +             ret = PTR_ERR(sy7636a->regmap);

> > +             dev_err(sy7636a->dev,

> > +                     "Failed to initialize register map: %d\n", ret);

> > +             return ret;

> > +     }

> > +

> > +     i2c_set_clientdata(client, sy7636a);

> > +

> > +     ret = sysfs_create_group(&client->dev.kobj, &sy7636a_sysfs_attr_group);

> > +     if (ret) {

> > +             dev_err(sy7636a->dev, "Failed to create sysfs attributes\n");

> > +             return ret;

> > +     }

> > +

> > +     ret = devm_mfd_add_devices(sy7636a->dev, PLATFORM_DEVID_AUTO,

> > +                                     sy7636a_cells, ARRAY_SIZE(sy7636a_cells),

> > +                                     NULL, 0, NULL);

> > +     if (ret) {

> > +             dev_err(sy7636a->dev, "Failed to add mfd devices\n");

>

> "Failed to add child devices"

>

> > +             sysfs_remove_group(&client->dev.kobj, &sy7636a_sysfs_attr_group);

> > +             return ret;

> > +     }

> > +

> > +     return 0;

> > +}

> > +

> > +static const struct i2c_device_id sy7636a_id_table[] = {

> > +     { "sy7636a", 0 },

> > +     { },

> > +};

> > +MODULE_DEVICE_TABLE(i2c, sy7636a_id_table);

>

> If you use .probe2, you can omit this table.

>

> > +static struct i2c_driver sy7636a_driver = {

> > +     .driver = {

> > +             .name   = "sy7636a",

> > +             .of_match_table = of_sy7636a_match_table,

> > +     },

> > +     .probe = sy7636a_probe,

> > +     .id_table = sy7636a_id_table,

> > +};

> > +module_i2c_driver(sy7636a_driver);

> > +

> > +MODULE_AUTHOR("Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>");

> > +MODULE_DESCRIPTION("Silergy SY7636A Multi-Function Device Driver");

>

> s/Multi-Function Device Driver/Power Management Chip/

>

> > +MODULE_LICENSE("GPL v2");

> > diff --git a/include/linux/mfd/sy7636a.h b/include/linux/mfd/sy7636a.h

> > new file mode 100644

> > index 000000000000..642789c4d0a9

> > --- /dev/null

> > +++ b/include/linux/mfd/sy7636a.h

> > @@ -0,0 +1,50 @@

> > +/* SPDX-License-Identifier: GPL-2.0-only */

> > +/*

> > + * Functions to access SY3686A power management chip.

> > + *

> > + * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/

> > + *

> > + * This program is free software; you can redistribute it and/or

> > + * modify it under the terms of the GNU General Public License as

> > + * published by the Free Software Foundation version 2.

> > + *

> > + * This program is distributed "as is" WITHOUT ANY WARRANTY of any

> > + * kind, whether express or implied; without even the implied warranty

> > + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

> > + * GNU General Public License for more details.

> > + */

>

> Same issues as mentioned above.

>

> > +#ifndef __LINUX_MFD_SY7636A_H

> > +#define __LINUX_MFD_SY7636A_H

>

> Just MFD is fine.

>

> > +#include <linux/i2c.h>

> > +#include <linux/regulator/driver.h>

> > +#include <linux/regulator/machine.h>

> > +#include <linux/regmap.h>

>

> Alphabetical.

>

> > +#define SY7636A_REG_OPERATION_MODE_CRL 0x00

> > +#define SY7636A_OPERATION_MODE_CRL_VCOMCTL (1 << 6)

> > +#define SY7636A_OPERATION_MODE_CRL_ONOFF (1 << 7)

> > +#define SY7636A_REG_VCOM_ADJUST_CTRL_L 0x01

> > +#define SY7636A_REG_VCOM_ADJUST_CTRL_H 0x02

> > +#define SY7636A_REG_VCOM_ADJUST_CTRL_MASK 0x01ff

> > +#define SY7636A_REG_VLDO_VOLTAGE_ADJULST_CTRL 0x03

> > +#define SY7636A_REG_POWER_ON_DELAY_TIME 0x06

> > +#define SY7636A_REG_FAULT_FLAG 0x07

> > +#define SY7636A_FAULT_FLAG_PG (1 << 0)

> > +#define SY7636A_REG_TERMISTOR_READOUT 0x08

>

> Tab out the values please.

>

> Use BIT()

>

> > +#define SY7636A_REG_MAX 0x08

> > +

> > +struct sy7636a {

> > +     struct device *dev;

> > +     struct regmap *regmap;

> > +     unsigned int vcom;

>

> Where is this used?

>

> > +     struct gpio_desc *pgood_gpio;

>

> Where is this used?

>

> > +     struct mutex reglock;

>

> Where is this used?


I have removed these.

>

> > +};

> > +

> > +int get_vcom_voltage_mv(struct regmap *regmap);

> > +int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom);

>

> What calls these?


I have just made these internal to the driver.


Alistair

>

> > +#endif /* __LINUX_MFD_SY7636A_H */

>

> --

> Lee Jones [李琼斯]

> Senior Technical Lead - Developer Services

> Linaro.org │ Open source software for Arm SoCs

> Follow Linaro: Facebook | Twitter | Blog
Lee Jones March 23, 2021, 9:35 a.m. UTC | #3
On Sat, 20 Mar 2021, Alistair Francis wrote:

> On Thu, Feb 4, 2021 at 5:31 AM Lee Jones <lee.jones@linaro.org> wrote:

> >

> > On Sat, 16 Jan 2021, Alistair Francis wrote:

> >

> > > Initial support for the Silergy SY7636A Power Management chip

> > > driver.

> >

> > Please remove "driver", as this is not support for the driver, it *is*

> > the driver which supports the chip.

> 

> Sorry for the long delay here.

> 

> I have addressed your comments.


[...]

> > > diff --git a/drivers/mfd/sy7636a.c b/drivers/mfd/sy7636a.c

> > > new file mode 100644

> > > index 000000000000..39aac965d854

> > > --- /dev/null

> > > +++ b/drivers/mfd/sy7636a.c

> > > @@ -0,0 +1,252 @@

> > > +// SPDX-License-Identifier: GPL-2.0+

> > > +/*

> > > + * MFD driver for SY7636A chip

> >

> > "Parent driver".

> >

> > > + * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/

> >

> > This is quite out of date.  Please update.

> 

> I don't own this copyright, so I would rather not change it.


I'm not comfortable taking a new driver with an old Copyright.

Maybe ask reMarkable if it's okay to bump it.

> > > + * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>


Or ping this guy.

[...]

> > > +int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom)

> > > +{

> > > +     int ret;

> > > +     unsigned int val;

> > > +

> > > +     if (vcom < 0 || vcom > 5000)

> >

> > Please define min/max values.

> >

> > > +             return -EINVAL;

> > > +

> > > +     val = (unsigned int)(vcom / 10) & 0x1ff;

> >

> > As above.

> 

> I have used defines for all of these.

> 

> >

> > > +     ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, val);

> > > +     if (ret)

> > > +             return ret;

> > > +

> > > +     ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, val >> 8);

> > > +     if (ret)

> > > +             return ret;

> > > +

> > > +     return 0;

> > > +}

> >

> > Who calls these?

> 

> They sysfs store and show functions.


They should be in a power/regulator driver really.

[...]

> > > +     if (val >= ARRAY_SIZE(states)) {

> > > +             dev_err(sy7636a->dev, "Unexpected value read from device: %u\n", val);

> > > +             return -EINVAL;

> > > +     }

> > > +

> > > +     return snprintf(buf, PAGE_SIZE, "%s\n", states[val]);

> > > +}

> > > +static DEVICE_ATTR(state, 0444, state_show, NULL);

> >

> > You need to document new sysfs entries.

> 

> I'm not sure how to document this. Do you mind pointing out an example

> I can use?


See the final paragraph in:

  Documentation/filesystems/sysfs.rst

[...]

> > > +static struct attribute *sy7636a_sysfs_attrs[] = {

> > > +     &dev_attr_state.attr,

> > > +     &dev_attr_power_good.attr,

> > > +     &dev_attr_vcom.attr,

> > > +     NULL,

> > > +};

> >

> > These all look like power options?  Do they really belong here?

> 

> From what I can tell I think they do. Let me know if you don't think so.


As above, I think they should be in power or regulator.

[...]

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
Alistair Francis March 25, 2021, 1:49 p.m. UTC | #4
On Tue, Mar 23, 2021 at 5:35 AM Lee Jones <lee.jones@linaro.org> wrote:
>

> On Sat, 20 Mar 2021, Alistair Francis wrote:

>

> > On Thu, Feb 4, 2021 at 5:31 AM Lee Jones <lee.jones@linaro.org> wrote:

> > >

> > > On Sat, 16 Jan 2021, Alistair Francis wrote:

> > >

> > > > Initial support for the Silergy SY7636A Power Management chip

> > > > driver.

> > >

> > > Please remove "driver", as this is not support for the driver, it *is*

> > > the driver which supports the chip.

> >

> > Sorry for the long delay here.

> >

> > I have addressed your comments.

>

> [...]

>

> > > > diff --git a/drivers/mfd/sy7636a.c b/drivers/mfd/sy7636a.c

> > > > new file mode 100644

> > > > index 000000000000..39aac965d854

> > > > --- /dev/null

> > > > +++ b/drivers/mfd/sy7636a.c

> > > > @@ -0,0 +1,252 @@

> > > > +// SPDX-License-Identifier: GPL-2.0+

> > > > +/*

> > > > + * MFD driver for SY7636A chip

> > >

> > > "Parent driver".

> > >

> > > > + * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/

> > >

> > > This is quite out of date.  Please update.

> >

> > I don't own this copyright, so I would rather not change it.

>

> I'm not comfortable taking a new driver with an old Copyright.

>

> Maybe ask reMarkable if it's okay to bump it.

>

> > > > + * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>

>

> Or ping this guy.


I reached out to him and have permission to bump the year.

>

> [...]

>

> > > > +int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom)

> > > > +{

> > > > +     int ret;

> > > > +     unsigned int val;

> > > > +

> > > > +     if (vcom < 0 || vcom > 5000)

> > >

> > > Please define min/max values.

> > >

> > > > +             return -EINVAL;

> > > > +

> > > > +     val = (unsigned int)(vcom / 10) & 0x1ff;

> > >

> > > As above.

> >

> > I have used defines for all of these.

> >

> > >

> > > > +     ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, val);

> > > > +     if (ret)

> > > > +             return ret;

> > > > +

> > > > +     ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, val >> 8);

> > > > +     if (ret)

> > > > +             return ret;

> > > > +

> > > > +     return 0;

> > > > +}

> > >

> > > Who calls these?

> >

> > They sysfs store and show functions.

>

> They should be in a power/regulator driver really.


Ok, I have moved these to the regulator.

>

> [...]

>

> > > > +     if (val >= ARRAY_SIZE(states)) {

> > > > +             dev_err(sy7636a->dev, "Unexpected value read from device: %u\n", val);

> > > > +             return -EINVAL;

> > > > +     }

> > > > +

> > > > +     return snprintf(buf, PAGE_SIZE, "%s\n", states[val]);

> > > > +}

> > > > +static DEVICE_ATTR(state, 0444, state_show, NULL);

> > >

> > > You need to document new sysfs entries.

> >

> > I'm not sure how to document this. Do you mind pointing out an example

> > I can use?

>

> See the final paragraph in:

>

>   Documentation/filesystems/sysfs.rst


Thanks!

>

> [...]

>

> > > > +static struct attribute *sy7636a_sysfs_attrs[] = {

> > > > +     &dev_attr_state.attr,

> > > > +     &dev_attr_power_good.attr,

> > > > +     &dev_attr_vcom.attr,

> > > > +     NULL,

> > > > +};

> > >

> > > These all look like power options?  Do they really belong here?

> >

> > From what I can tell I think they do. Let me know if you don't think so.

>

> As above, I think they should be in power or regulator.


Done.

Alistair

>

> [...]

>

> --

> Lee Jones [李琼斯]

> Senior Technical Lead - Developer Services

> Linaro.org │ Open source software for Arm SoCs

> Follow Linaro: Facebook | Twitter | Blog
diff mbox series

Patch

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index bdfce7b15621..c8c62d92433c 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -1360,6 +1360,16 @@  config MFD_SYSCON
 	  Select this option to enable accessing system control registers
 	  via regmap.
 
+config MFD_SY7636A
+	tristate "Silergy SY7636A Power Management chip driver"
+	select MFD_CORE
+	select REGMAP_I2C
+	select REGMAP_IRQ
+	depends on I2C=y
+	help
+	  Select this option to enable support for the Silergy SY7636A
+	  Power Management chip driver.
+
 config MFD_DAVINCI_VOICECODEC
 	tristate
 	select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 14fdb188af02..1fa1e635f506 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -265,6 +265,8 @@  obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o
 obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o
 obj-$(CONFIG_MFD_KHADAS_MCU) 	+= khadas-mcu.o
 
+obj-$(CONFIG_MFD_SY7636A)	+= sy7636a.o
+
 obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o
 obj-$(CONFIG_MFD_SIMPLE_MFD_I2C)	+= simple-mfd-i2c.o
 obj-$(CONFIG_MFD_INTEL_M10_BMC)   += intel-m10-bmc.o
diff --git a/drivers/mfd/sy7636a.c b/drivers/mfd/sy7636a.c
new file mode 100644
index 000000000000..39aac965d854
--- /dev/null
+++ b/drivers/mfd/sy7636a.c
@@ -0,0 +1,252 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * MFD driver for SY7636A chip
+ *
+ * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
+ *
+ * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Based on the lp87565 driver by Keerthy <j-keerthy@ti.com>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/sysfs.h>
+
+#include <linux/mfd/sy7636a.h>
+
+static const struct regmap_config sy7636a_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct mfd_cell sy7636a_cells[] = {
+	{ .name = "sy7636a-regulator", },
+	{ .name = "sy7636a-temperature", },
+	{ .name = "sy7636a-thermal", },
+};
+
+static const struct of_device_id of_sy7636a_match_table[] = {
+	{ .compatible = "silergy,sy7636a", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, of_sy7636a_match_table);
+
+static const char * const states[] = {
+	"no fault event",
+	"UVP at VP rail",
+	"UVP at VN rail",
+	"UVP at VPOS rail",
+	"UVP at VNEG rail",
+	"UVP at VDDH rail",
+	"UVP at VEE rail",
+	"SCP at VP rail",
+	"SCP at VN rail",
+	"SCP at VPOS rail",
+	"SCP at VNEG rail",
+	"SCP at VDDH rail",
+	"SCP at VEE rail",
+	"SCP at V COM rail",
+	"UVLO",
+	"Thermal shutdown",
+};
+
+int get_vcom_voltage_mv(struct regmap *regmap)
+{
+	int ret;
+	unsigned int val, val_h;
+
+	ret = regmap_read(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, &val);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, &val_h);
+	if (ret)
+		return ret;
+
+	val |= (val_h << 8);
+
+	return (val & 0x1FF) * 10;
+}
+
+int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom)
+{
+	int ret;
+	unsigned int val;
+
+	if (vcom < 0 || vcom > 5000)
+		return -EINVAL;
+
+	val = (unsigned int)(vcom / 10) & 0x1ff;
+
+	ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_L, val);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(regmap, SY7636A_REG_VCOM_ADJUST_CTRL_H, val >> 8);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static ssize_t state_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	int ret;
+	unsigned int val;
+	struct sy7636a *sy7636a = dev_get_drvdata(dev);
+
+	ret = regmap_read(sy7636a->regmap, SY7636A_REG_FAULT_FLAG, &val);
+	if (ret) {
+		dev_err(sy7636a->dev, "Failed to read from device\n");
+		return ret;
+	}
+
+	val = val >> 1;
+
+	if (val >= ARRAY_SIZE(states)) {
+		dev_err(sy7636a->dev, "Unexpected value read from device: %u\n", val);
+		return -EINVAL;
+	}
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", states[val]);
+}
+static DEVICE_ATTR(state, 0444, state_show, NULL);
+
+static ssize_t power_good_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	int ret;
+	unsigned int val;
+	struct sy7636a *sy7636a = dev_get_drvdata(dev);
+
+	ret = regmap_read(sy7636a->regmap, SY7636A_REG_FAULT_FLAG, &val);
+	if (ret) {
+		dev_err(sy7636a->dev, "Failed to read from device\n");
+		return ret;
+	}
+
+	val &= 0x01;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", val ? "ON" : "OFF");
+}
+static DEVICE_ATTR(power_good, 0444, power_good_show, NULL);
+
+static ssize_t vcom_show(struct device *dev, struct device_attribute *attr,
+		char *buf)
+{
+	int ret;
+	struct sy7636a *sy7636a = dev_get_drvdata(dev);
+
+	ret = get_vcom_voltage_mv(sy7636a->regmap);
+	if (ret < 0)
+		return ret;
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", -ret);
+}
+
+static ssize_t vcom_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	int ret;
+	int vcom;
+	struct sy7636a *sy7636a = dev_get_drvdata(dev);
+
+	ret = kstrtoint(buf, 0, &vcom);
+	if (ret)
+		return ret;
+
+	if (vcom > 0 || vcom < -5000)
+		return -EINVAL;
+
+	ret = set_vcom_voltage_mv(sy7636a->regmap, (unsigned int)(-vcom));
+	if (ret)
+		return ret;
+
+	return count;
+}
+static DEVICE_ATTR(vcom, 0644, vcom_show, vcom_store);
+
+static struct attribute *sy7636a_sysfs_attrs[] = {
+	&dev_attr_state.attr,
+	&dev_attr_power_good.attr,
+	&dev_attr_vcom.attr,
+	NULL,
+};
+
+static const struct attribute_group sy7636a_sysfs_attr_group = {
+	.attrs = sy7636a_sysfs_attrs,
+};
+
+static int sy7636a_probe(struct i2c_client *client,
+			 const struct i2c_device_id *ids)
+{
+	struct sy7636a *sy7636a;
+	int ret;
+
+	sy7636a = devm_kzalloc(&client->dev, sizeof(struct sy7636a), GFP_KERNEL);
+	if (sy7636a == NULL)
+		return -ENOMEM;
+
+	sy7636a->dev = &client->dev;
+
+	sy7636a->regmap = devm_regmap_init_i2c(client, &sy7636a_regmap_config);
+	if (IS_ERR(sy7636a->regmap)) {
+		ret = PTR_ERR(sy7636a->regmap);
+		dev_err(sy7636a->dev,
+			"Failed to initialize register map: %d\n", ret);
+		return ret;
+	}
+
+	i2c_set_clientdata(client, sy7636a);
+
+	ret = sysfs_create_group(&client->dev.kobj, &sy7636a_sysfs_attr_group);
+	if (ret) {
+		dev_err(sy7636a->dev, "Failed to create sysfs attributes\n");
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(sy7636a->dev, PLATFORM_DEVID_AUTO,
+					sy7636a_cells, ARRAY_SIZE(sy7636a_cells),
+					NULL, 0, NULL);
+	if (ret) {
+		dev_err(sy7636a->dev, "Failed to add mfd devices\n");
+		sysfs_remove_group(&client->dev.kobj, &sy7636a_sysfs_attr_group);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct i2c_device_id sy7636a_id_table[] = {
+	{ "sy7636a", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, sy7636a_id_table);
+
+static struct i2c_driver sy7636a_driver = {
+	.driver	= {
+		.name	= "sy7636a",
+		.of_match_table = of_sy7636a_match_table,
+	},
+	.probe = sy7636a_probe,
+	.id_table = sy7636a_id_table,
+};
+module_i2c_driver(sy7636a_driver);
+
+MODULE_AUTHOR("Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>");
+MODULE_DESCRIPTION("Silergy SY7636A Multi-Function Device Driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/mfd/sy7636a.h b/include/linux/mfd/sy7636a.h
new file mode 100644
index 000000000000..642789c4d0a9
--- /dev/null
+++ b/include/linux/mfd/sy7636a.h
@@ -0,0 +1,50 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Functions to access SY3686A power management chip.
+ *
+ * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __LINUX_MFD_SY7636A_H
+#define __LINUX_MFD_SY7636A_H
+
+#include <linux/i2c.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regmap.h>
+
+#define SY7636A_REG_OPERATION_MODE_CRL 0x00
+#define SY7636A_OPERATION_MODE_CRL_VCOMCTL (1 << 6)
+#define SY7636A_OPERATION_MODE_CRL_ONOFF (1 << 7)
+#define SY7636A_REG_VCOM_ADJUST_CTRL_L 0x01
+#define SY7636A_REG_VCOM_ADJUST_CTRL_H 0x02
+#define SY7636A_REG_VCOM_ADJUST_CTRL_MASK 0x01ff
+#define SY7636A_REG_VLDO_VOLTAGE_ADJULST_CTRL 0x03
+#define SY7636A_REG_POWER_ON_DELAY_TIME 0x06
+#define SY7636A_REG_FAULT_FLAG 0x07
+#define SY7636A_FAULT_FLAG_PG (1 << 0)
+#define SY7636A_REG_TERMISTOR_READOUT 0x08
+
+#define SY7636A_REG_MAX 0x08
+
+struct sy7636a {
+	struct device *dev;
+	struct regmap *regmap;
+	unsigned int vcom;
+	struct gpio_desc *pgood_gpio;
+	struct mutex reglock;
+};
+
+int get_vcom_voltage_mv(struct regmap *regmap);
+int set_vcom_voltage_mv(struct regmap *regmap, unsigned int vcom);
+
+#endif /* __LINUX_MFD_SY7636A_H */