Date:   Mon, 22 May 2017 12:54:20 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Valentin Sitdikov <valentin_sitdikov@...tor.com>
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrei Dranitca <Andrei_Dranitca@...tor.com>
Subject: Re: [PATCH 2/2] mfd: max7360: Add mfd core device driver

On Thu, 18 May 2017, Valentin Sitdikov wrote:

> From: Andrei Dranitca <Andrei_Dranitca@...tor.com>
> 
> This patch adds core/irq driver to support MAX7360 i2c chip

IRQ and I2C

> which contains keypad, gpio, pwm, gpo and rotary encoder submodules.

GPIO, PWM and GPO

> Signed-off-by: Valentin Sitdikov <valentin_sitdikov@...tor.com>
> Signed-off-by: Andrei Dranitca <Andrei_Dranitca@...tor.com>

These are in the wrong order.

> ---
>  drivers/mfd/Kconfig         |  16 ++
>  drivers/mfd/Makefile        |   1 +
>  drivers/mfd/max7360.c       | 397 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/max7360.h | 130 +++++++++++++++
>  4 files changed, 544 insertions(+)
>  create mode 100644 drivers/mfd/max7360.c
>  create mode 100644 include/linux/mfd/max7360.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 3eb5c93..894c2e9 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -721,6 +721,22 @@ config MFD_MAX8998
>  	  additional drivers must be enabled in order to use the functionality
>  	  of the device.
>  
> +config MFD_MAX7360
> +	tristate "Maxim Semiconductor MAX7360 support"
> +	depends on I2C && OF
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	select IRQ_DOMAIN
> +	help
> +	  Say yes here to add support for Maxim Semiconductor MAX7360.
> +	  This provides microprocessors with management of up to 64 key switches,
> +	  with an additional eight LED drivers/GPIOs that feature constant-current,
> +	  PWM intensity control, and rotary switch control options.
> +
> +	  This driver provides common support for accessing the device,
> +	  additional drivers must be enabled in order to use the functionality
> +	  of the device.
> +
>  config MFD_MT6397
>  	tristate "MediaTek MT6397 PMIC Support"
>  	select MFD_CORE
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index c16bf1e..9e721c0 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -137,6 +137,7 @@ obj-$(CONFIG_MFD_DA9063)	+= da9063.o
>  obj-$(CONFIG_MFD_DA9150)	+= da9150-core.o
>  
>  obj-$(CONFIG_MFD_MAX14577)	+= max14577.o
> +obj-$(CONFIG_MFD_MAX7360)	+= max7360.o
>  obj-$(CONFIG_MFD_MAX77620)	+= max77620.o
>  obj-$(CONFIG_MFD_MAX77686)	+= max77686.o
>  obj-$(CONFIG_MFD_MAX77693)	+= max77693.o
> diff --git a/drivers/mfd/max7360.c b/drivers/mfd/max7360.c
> new file mode 100644
> index 0000000..566434e
> --- /dev/null
> +++ b/drivers/mfd/max7360.c
> @@ -0,0 +1,397 @@
> +/*
> + * Copyright (C) 2017 Mentor Graphics
> + *
> + * Author: Valentin Sitdikov <Valentin.Sitdikov@...tor.com>
> + * Author: Andrei Dranitca <Andrei_Dranitca@...tor.com>

Order?

> + * 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; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *

Remove the line above.

Do you have to use the full licence header?  There is a short version,
any reason why you can't use it?

> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/max7360.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/of_irq.h>
> +#include <linux/slab.h>
> +
> +
> +int max7360_request_pin(struct max7360 *max7360, u8 pin)
> +{
> +	struct i2c_client *client = max7360->i2c;
> +	int ret = 0;

No need to pre-initialise.  Just return 0 at the end.

> +	spin_lock(&max7360->lock);
> +	if (max7360->gpio_pins & BIT(pin)) {
> +		dev_err(&client->dev, "pin %d already requested, mask %x",
> +		       pin, max7360->gpio_pins);
> +		spin_unlock(&max7360->lock);
> +		return -EBUSY;
> +	}
> +	max7360->gpio_pins |= BIT(pin);
> +	dev_dbg(&client->dev, "pin %d requested successfully", pin);
> +	spin_unlock(&max7360->lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(max7360_request_pin);
> +
> +void max7360_free_pin(struct max7360 *max7360, u8 pin)
> +{
> +	spin_lock(&max7360->lock);
> +	max7360->gpio_pins &= ~BIT(pin);
> +	spin_unlock(&max7360->lock);
> +}
> +EXPORT_SYMBOL_GPL(max7360_free_pin);

What do these pins do?  Are they GPIOs?

If so, why aren't you using the GPIO API?

> +static const struct mfd_cell max7360_devices[] = {
> +	{
> +		.name           = "max7360-gpio",
> +		.of_compatible	= "maxim,max7360-gpio",
> +	},
> +	{
> +		.name           = "max7360-keypad",
> +		.of_compatible	= "maxim,max7360-keypad",
> +	},
> +	{
> +		.name           = "max7360-pwm",
> +		.of_compatible	= "maxim,max7360-pwm",
> +	},
> +	{
> +		.name           = "max7360-rotary",
> +		.of_compatible	= "maxim,max7360-rotary",
> +	},
> +};
> +
> +static irqreturn_t max7360_irq(int irq, void *data)
> +{
> +	struct max7360 *max7360 = data;
> +	int virq;
> +
> +	virq = irq_find_mapping(max7360->domain, MAX7360_INT_GPIO);
> +	handle_nested_irq(virq);
> +	virq = irq_find_mapping(max7360->domain, MAX7360_INT_KEYPAD);
> +	handle_nested_irq(virq);
> +	virq = irq_find_mapping(max7360->domain, MAX7360_INT_ROTARY);
> +	handle_nested_irq(virq);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t max7360_irqi(int irq, void *data)
> +{
> +	struct max7360 *max7360 = data;
> +	int virq;
> +
> +	virq = irq_find_mapping(max7360->domain, MAX7360_INT_GPIO);
> +	handle_nested_irq(virq);
> +	virq = irq_find_mapping(max7360->domain, MAX7360_INT_ROTARY);
> +	handle_nested_irq(virq);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t max7360_irqk(int irq, void *data)
> +{
> +	struct max7360 *max7360 = data;
> +	int virq;
> +
> +	virq = irq_find_mapping(max7360->domain, MAX7360_INT_KEYPAD);
> +	handle_nested_irq(virq);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int max7360_irq_map(struct irq_domain *d, unsigned int virq,
> +			  irq_hw_number_t hwirq)
> +{
> +	struct max7360 *max7360 = d->host_data;
> +
> +	irq_set_chip_data(virq, max7360);
> +	irq_set_chip_and_handler(virq, &dummy_irq_chip,
> +				handle_edge_irq);
> +	irq_set_nested_thread(virq, 1);
> +	irq_set_noprobe(virq);
> +
> +	return 0;
> +}
> +
> +static void max7360_irq_unmap(struct irq_domain *d, unsigned int virq)
> +{
> +	irq_set_chip_and_handler(virq, NULL, NULL);
> +	irq_set_chip_data(virq, NULL);
> +}
> +
> +static const struct irq_domain_ops max7360_irq_ops = {
> +	.map    = max7360_irq_map,
> +	.unmap  = max7360_irq_unmap,
> +	.xlate  = irq_domain_xlate_onecell,
> +};
> +
> +static int max7360_irq_init(struct max7360 *max7360, struct device_node *np)
> +{
> +	int ret;
> +
> +	max7360->inti = of_irq_get_byname(np, "inti");
> +	max7360->intk = of_irq_get_byname(np, "intk");
> +
> +	if (max7360->inti < 0) {
> +		dev_err(max7360->dev, "no inti provided");
> +		return -ENODEV;
> +	}
> +
> +	if (max7360->intk < 0) {
> +		dev_err(max7360->dev, "no intk provided");
> +		return -ENODEV;
> +	}

It's more conformant to place the ifs directly after where the
variable under test is initialised.

> +	if (max7360->inti == max7360->intk) {

You need a comment here to explain exactly why this is required.

> +		max7360->shared_irq = max7360->inti;
> +		ret = request_threaded_irq(max7360->shared_irq, NULL,
> +					  max7360_irq,
> +					  IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +					  "max7360", max7360);
> +		if (ret) {
> +			dev_err(max7360->dev, "failed to request IRQ: %d\n",
> +				ret);
> +			return ret;
> +		}
> +	} else {
> +		max7360->shared_irq = 0;
> +		ret = request_threaded_irq(max7360->inti, NULL, max7360_irqi,
> +					  IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +					  "max7360", max7360);
> +		if (ret) {
> +			dev_err(max7360->dev, "failed to request inti IRQ: %d\n",
> +			       ret);
> +			return ret;
> +		}
> +
> +		ret = request_threaded_irq(max7360->intk, NULL, max7360_irqk,
> +					  IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +					  "max7360", max7360);
> +		if (ret) {
> +			free_irq(max7360->inti, max7360);
> +			dev_err(max7360->dev, "failed to request intk IRQ: %d\n",
> +				ret);
> +			return ret;
> +		}
> +	}
> +
> +	max7360->domain = irq_domain_add_simple(np, MAX7360_NR_INTERNAL_IRQS,
> +					       0, &max7360_irq_ops, max7360);
> +
> +	if (!max7360->domain) {
> +		if (max7360->shared_irq)
> +			free_irq(max7360->shared_irq, max7360);
> +		else {
> +			free_irq(max7360->inti, max7360);
> +			free_irq(max7360->intk, max7360);
> +		}
> +		dev_err(max7360->dev, "Failed to create irqdomain\n");
> +		return -ENODEV;
> +	}
> +
> +	irq_create_mapping(max7360->domain, MAX7360_INT_GPIO);
> +	irq_create_mapping(max7360->domain, MAX7360_INT_KEYPAD);
> +	irq_create_mapping(max7360->domain, MAX7360_INT_ROTARY);

Why aren't you checking the return values of these calls?

> +	return 0;
> +}
> +
> +void max7360_fall_deepsleep(struct max7360 *max7360)

Drop the "_fall"

> +{
> +	max7360_write_reg(max7360, MAX7360_REG_SLEEP, MAX7360_AUTOSLEEP_8192);
> +}
> +EXPORT_SYMBOL_GPL(max7360_fall_deepsleep);
> +
> +void max7360_take_catnap(struct max7360 *max7360)

The naming of the function can and should be improved.

> +{
> +	max7360_write_reg(max7360, MAX7360_REG_SLEEP, MAX7360_AUTOSLEEP_256);
> +}
> +EXPORT_SYMBOL_GPL(max7360_take_catnap);

What is calling these functions?

> +static int max7360_chip_init(struct max7360 *max7360)
> +{
> +	max7360->gpio_pins = MAX7360_MAX_GPIO;
> +	max7360->gpo_count = 0;
> +	max7360->col_count = MAX7360_COL_GPO_PINS;

This does not require its own function.

> +	return 0;
> +}
> +
> +static int max7360_device_init(struct max7360 *max7360)
> +{
> +	int ret = 0;

No need to pre-initialise.

> +	ret = mfd_add_devices(max7360->dev, -1, max7360_devices,

Use the #defines, not -1.

> +			     ARRAY_SIZE(max7360_devices), NULL,
> +			     0, max7360->domain);
> +	if (ret)
> +		dev_err(max7360->dev, "failed to add child devices\n");
> +
> +	return ret;
> +}
> +
> +int max7360_request_gpo_pin_count(struct max7360 *max7360, u8 count)
> +{
> +	if (count > MAX7360_MAX_GPO)
> +		return -EINVAL;

'\n'

> +	if (max7360->col_count + count > MAX7360_COL_GPO_PINS) {
> +		dev_err(max7360->dev,
> +		       "trying to request %d pins as gpo while %d pins already used as COL\n",
> +		       count, max7360->col_count);
> +		return -EINVAL;
> +	}
> +	max7360->gpo_count = count;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(max7360_request_gpo_pin_count);
> +
> +int max7360_request_col_count(struct max7360 *max7360, u8 count)
> +{
> +	if (max7360->gpo_count + count > MAX7360_COL_GPO_PINS) {
> +		dev_err(max7360->dev,
> +		       "trying to request %d pins as COL while %d pins already used as gpo\n",
> +		       count, max7360->gpo_count);
> +		return -EINVAL;
> +	}
> +	max7360->col_count = count;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(max7360_request_col_count);

What is the purpose of these two functions?

> +static const struct regmap_range max7360_volatile_ranges[] = {
> +	{
> +		.range_min = MAX7360_REG_KEYFIFO,
> +		.range_max = MAX7360_REG_KEYFIFO,
> +	}, {
> +		.range_min = 0x48,
> +		.range_max = 0x4a,

No magic numbers please.

> +	},
> +};
> +
> +static const struct regmap_access_table max7360_volatile_table = {
> +	.yes_ranges = max7360_volatile_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(max7360_volatile_ranges),
> +};
> +
> +static const struct regmap_config max7360_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = 0xff,
> +	.volatile_table = &max7360_volatile_table,
> +	.cache_type = REGCACHE_RBTREE,
> +};
> +
> +static int max7360_probe(struct i2c_client *i2c,
> +			const struct i2c_device_id *id)
> +{
> +	struct device_node *np = i2c->dev.of_node;
> +	struct max7360 *max7360;
> +

Remove this line.

> +	int ret;
> +
> +	max7360 = devm_kzalloc(&i2c->dev, sizeof(struct max7360),
> +			      GFP_KERNEL);
> +	if (!max7360)
> +		return -ENOMEM;
> +
> +	spin_lock_init(&max7360->lock);
> +
> +	max7360->dev = &i2c->dev;
> +	max7360->i2c = i2c;
> +
> +	i2c_set_clientdata(i2c, max7360);
> +
> +	max7360->regmap = devm_regmap_init_i2c(i2c, &max7360_regmap_config);
> +	ret = max7360_chip_init(max7360);
> +	if (ret)
> +		return ret;
> +
> +	ret = max7360_irq_init(max7360, np);
> +	if (ret)
> +		return ret;
> +
> +	ret = max7360_device_init(max7360);
> +	if (ret) {
> +		dev_err(max7360->dev, "failed to add child devices\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int max7360_remove(struct i2c_client *client)
> +{
> +	struct max7360 *max7360 = i2c_get_clientdata(client);
> +
> +	mfd_remove_devices(max7360->dev);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int max7360_suspend(struct device *dev)
> +{
> +	return 0;
> +}
> +
> +static int max7360_resume(struct device *dev)
> +{
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(max7360_dev_pm_ops, max7360_suspend, max7360_resume);

Why are you pretending that you support runtime PM?

> +static const struct of_device_id max7360_match[] = {
> +	{ .compatible = "maxim,max7360" },
> +	{ }
> +};
> +

Remove this line.

> +MODULE_DEVICE_TABLE(of, max7360_match);
> +
> +static const struct i2c_device_id max7360_id[] = {
> +	{ "max7360", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, max7360_id);

What are you using this table for?

> +static struct i2c_driver max7360_driver = {
> +	.driver = {
> +		.name	= "max7360",
> +		.pm	= &max7360_dev_pm_ops,
> +		.of_match_table = max7360_match,
> +	},
> +	.probe		= max7360_probe,
> +	.remove		= max7360_remove,
> +	.id_table	= max7360_id,
> +};
> +
> +static int __init max7360_init(void)
> +{
> +	return i2c_add_driver(&max7360_driver);
> +}
> +subsys_initcall(max7360_init);
> +
> +static void __exit max7360_exit(void)
> +{
> +	i2c_del_driver(&max7360_driver);
> +}
> +module_exit(max7360_exit);

This looks like boiler plate.

Please see if there is a helper function for this.

> +MODULE_LICENSE("GPL v2");

This does not match the header comment.

> +MODULE_DESCRIPTION("MAX7360 MFD core driver");
> diff --git a/include/linux/mfd/max7360.h b/include/linux/mfd/max7360.h
> new file mode 100644
> index 0000000..d139ddd
> --- /dev/null
> +++ b/include/linux/mfd/max7360.h
> @@ -0,0 +1,130 @@
> +#ifndef __LINUX_MFD_MAX7360_H
> +#define __LINUX_MFD_MAX7360_H
> +#include <linux/regmap.h>
> +
> +#define MAX7360_MAX_KEY_ROWS	8
> +#define MAX7360_MAX_KEY_COLS	8
> +#define MAX7360_MAX_KEY_NUM	(MAX7360_MAX_KEY_ROWS * MAX7360_MAX_KEY_COLS)
> +#define MAX7360_ROW_SHIFT	3
> +
> +#define MAX7360_MAX_GPIO 8
> +#define MAX7360_MAX_GPO 6
> +#define MAX7360_COL_GPO_PINS 8
> +/*
> + * MAX7360 registers
> + */
> +#define MAX7360_REG_KEYFIFO	0x00
> +#define MAX7360_REG_CONFIG	0x01
> +#define MAX7360_REG_DEBOUNCE	0x02
> +#define MAX7360_REG_INTERRUPT	0x03
> +#define MAX7360_REG_PORTS	0x04
> +#define MAX7360_REG_KEYREP	0x05
> +#define MAX7360_REG_SLEEP	0x06
> +
> +/*
> + * MAX7360 registers
> + */
> +#define MAX7360_REG_GPIOCFG	0x40
> +#define MAX7360_REG_GPIOCTRL	0x41
> +#define MAX7360_REG_GPIODEB	0x42
> +#define MAX7360_REG_GPIOCURR	0x43
> +#define MAX7360_REG_GPIOOUTM	0x44
> +#define MAX7360_REG_PWMCOM	0x45
> +#define MAX7360_REG_RTRCFG	0x46
> +#define MAX7360_REG_GPIOIN	0x49
> +#define MAX7360_REG_RTR_CNT	0x4A
> +#define MAX7360_REG_PWMBASE	0x50
> +#define MAX7360_REG_PWMCFG	0x58
> +
> +
> +#define MAX7360_REG_PORTCFGBASE 0x58
> +
> +/*
> + * Configuration register bits
> + */
> +#define MAX7360_CFG_SLEEP	(1 << 7)
> +#define MAX7360_CFG_INTERRUPT	(1 << 5)
> +#define MAX7360_CFG_KEY_RELEASE	(1 << 3)
> +#define MAX7360_CFG_WAKEUP	(1 << 1)
> +#define MAX7360_CFG_TIMEOUT	(1 << 0)

Use BIT()

> +/*
> + * Autosleep register values (ms)
> + */
> +#define MAX7360_AUTOSLEEP_8192	0x01
> +#define MAX7360_AUTOSLEEP_4096	0x02
> +#define MAX7360_AUTOSLEEP_2048	0x03
> +#define MAX7360_AUTOSLEEP_1024	0x04
> +#define MAX7360_AUTOSLEEP_512	0x05
> +#define MAX7360_AUTOSLEEP_256	0x06
> +
> +#define MAX7360_INT_INTI	0
> +#define MAX7360_INT_INTK	1
> +
> +#define MAX7360_INT_GPIO   0
> +#define MAX7360_INT_KEYPAD 1
> +#define MAX7360_INT_ROTARY 2
> +
> +#define MAX7360_NR_INTERNAL_IRQS	3
> +
> +struct max7360 {
> +	spinlock_t lock;		/* lock access to the structure */
> +	struct device *dev;
> +	struct i2c_client *i2c;
> +	struct irq_domain *domain;
> +	struct regmap *regmap;
> +
> +	int irq_base;
> +	int num_gpio;
> +	int shared_irq;
> +	int inti;
> +	int intk;

At no point do you explain what inti and inik is or the differences
between them.  I suggest you add a kerneldoc header to this struct,
AND consider renaming them to something a little more descriptive,
since 'l' and 'k', even when prefixed with 'int' are not good variable
names.

> +	u8 gpio_pins;
> +	u8 col_count;
> +	u8 gpo_count;
> +};
> +
> +static inline int max7360_read_reg(struct max7360 *max7360, int reg)
> +{
> +	unsigned int ival;
> +	int ret;
> +
> +	ret = regmap_read(max7360->regmap, reg, &ival);
> +	if (!ret)
> +		return ival;
> +	return 0;
> +}
> +
> +static inline int max7360_write_reg(struct max7360 *max7360, u8 reg, u8 val)
> +{
> +	return regmap_write(max7360->regmap, reg, val);
> +}
> +
> +static inline int max7360_set_bits(struct max7360 *max7360, u8 reg,
> +				  unsigned int bit_mask)
> +{
> +	return regmap_update_bits(max7360->regmap, reg, bit_mask, bit_mask);
> +}
> +
> +static inline int max7360_clr_bits(struct max7360 *max7360, u8 reg,
> +				  unsigned int bit_mask)
> +{
> +	return regmap_update_bits(max7360->regmap, reg, bit_mask, 0);
> +}
> +
> +static inline int max7360_update(struct max7360 *max7360, u8 reg, u8 val,
> +				unsigned int bit_mask)
> +{
> +	return regmap_update_bits(max7360->regmap, reg, bit_mask, val);
> +}
> +
> +int max7360_request_pin(struct max7360 *max7360, u8 pin);
> +void max7360_free_pin(struct max7360 *max7360, u8 pin);
> +
> +void max7360_take_catnap(struct max7360 *max7360);
> +void max7360_fall_deepsleep(struct max7360 *max7360);
> +
> +int max7360_request_gpo_pin_count(struct max7360 *max7360, u8 count);
> +int max7360_request_col_count(struct max7360 *max7360, u8 count);

What are all these functions for?

I think you should remove them all.

> +#endif

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