Date:   Tue, 9 Oct 2018 02:55:04 -0700
From:   Lee Jones <lee.jones@...aro.org>
To:     Amelie Delaunay <amelie.delaunay@...com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH v3 2/7] mfd: Add ST Multi-Function eXpander (STMFX) core
 driver

On Thu, 27 Sep 2018, Amelie Delaunay wrote:

> STMicroelectronics Multi-Function eXpander (STMFX) is a slave controller
> using I2C for communication with the main MCU. Main features are:
> - 16 fast GPIOs individually configurable in input/output
> - 8 alternate GPIOs individually configurable in input/output when other
> STMFX functions are not used
> - Main MCU IDD measurement
> - Resistive touchscreen controller
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay@...com>
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> ---
>  drivers/mfd/Kconfig       |  14 ++
>  drivers/mfd/Makefile      |   2 +-
>  drivers/mfd/stmfx.c       | 626 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/stmfx.h |  27 ++
>  4 files changed, 668 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/mfd/stmfx.c
>  create mode 100644 include/linux/mfd/stmfx.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index f3a5f8d..8c41342 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1862,6 +1862,20 @@ config MFD_STM32_TIMERS
>  	  for PWM and IIO Timer. This driver allow to share the
>  	  registers between the others drivers.
>  
> +config MFD_STMFX
> +	tristate "Support for STMicroelectronics Multi-Function eXpander (STMFX)"
> +	depends on I2C
> +	depends on OF || COMPILE_TEST
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	help
> +	  Support for the STMicroelectronics Multi-Function eXpander.
> +
> +	  This driver provides common support for accessing the device,
> +	  additional drivers must be enabled in order to use the functionality
> +	  of the device.
> +
> +
>  menu "Multimedia Capabilities Port drivers"
>  	depends on ARCH_SA1100
>  
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 5856a94..282323b 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -240,4 +240,4 @@ obj-$(CONFIG_MFD_MXS_LRADC)     += mxs-lradc.o
>  obj-$(CONFIG_MFD_SC27XX_PMIC)	+= sprd-sc27xx-spi.o
>  obj-$(CONFIG_RAVE_SP_CORE)	+= rave-sp.o
>  obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o
> -
> +obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o
> diff --git a/drivers/mfd/stmfx.c b/drivers/mfd/stmfx.c
> new file mode 100644
> index 0000000..cfd4fca
> --- /dev/null
> +++ b/drivers/mfd/stmfx.c
> @@ -0,0 +1,626 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for STMicroelectronics Multi-Function eXpander (STMFX) core
> + *
> + * Copyright (C) 2018 STMicroelectronics
> + * Author(s): Amelie Delaunay <amelie.delaunay@...com>.
> + */
> +#include <linux/bitfield.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/stmfx.h>
> +#include <linux/module.h>
> +#include <linux/regulator/consumer.h>
> +
> +/* General */
> +#define STMFX_REG_CHIP_ID		0x00 /* R */
> +#define STMFX_REG_FW_VERSION_MSB	0x01 /* R */
> +#define STMFX_REG_FW_VERSION_LSB	0x02 /* R */
> +#define STMFX_REG_SYS_CTRL		0x40 /* RW */
> +/* IRQ output management */
> +#define STMFX_REG_IRQ_OUT_PIN		0x41 /* RW */
> +#define STMFX_REG_IRQ_SRC_EN		0x42 /* RW */
> +#define STMFX_REG_IRQ_PENDING		0x08 /* R */
> +#define STMFX_REG_IRQ_ACK		0x44 /* RW */
> +/* GPIO management */
> +#define STMFX_REG_IRQ_GPI_PENDING1	0x0C /* R */
> +#define STMFX_REG_IRQ_GPI_PENDING2	0x0D /* R */
> +#define STMFX_REG_IRQ_GPI_PENDING3	0x0E /* R */
> +#define STMFX_REG_GPIO_STATE1		0x10 /* R */
> +#define STMFX_REG_GPIO_STATE2		0x11 /* R */
> +#define STMFX_REG_GPIO_STATE3		0x12 /* R */
> +#define STMFX_REG_IRQ_GPI_SRC1		0x48 /* RW */
> +#define STMFX_REG_IRQ_GPI_SRC2		0x49 /* RW */
> +#define STMFX_REG_IRQ_GPI_SRC3		0x4A /* RW */
> +#define STMFX_REG_GPO_SET1		0x6C /* RW */
> +#define STMFX_REG_GPO_SET2		0x6D /* RW */
> +#define STMFX_REG_GPO_SET3		0x6E /* RW */
> +#define STMFX_REG_GPO_CLR1		0x70 /* RW */
> +#define STMFX_REG_GPO_CLR2		0x71 /* RW */
> +#define STMFX_REG_GPO_CLR3		0x72 /* RW */
> +
> +#define STMFX_REG_MAX			0xB0
> +
> +/* MFX boot time is around 10ms, so after reset, we have to wait this delay */
> +#define STMFX_BOOT_TIME_MS 10
> +
> +/* STMFX_REG_CHIP_ID bitfields */
> +#define STMFX_REG_CHIP_ID_MASK		GENMASK(7, 0)
> +
> +/* STMFX_REG_SYS_CTRL bitfields */
> +#define STMFX_REG_SYS_CTRL_GPIO_EN	BIT(0)
> +#define STMFX_REG_SYS_CTRL_TS_EN	BIT(1)
> +#define STMFX_REG_SYS_CTRL_IDD_EN	BIT(2)
> +#define STMFX_REG_SYS_CTRL_ALTGPIO_EN	BIT(3)
> +#define STMFX_REG_SYS_CTRL_SWRST	BIT(7)
> +
> +/* STMFX_REG_IRQ_OUT_PIN bitfields */
> +#define STMFX_REG_IRQ_OUT_PIN_TYPE	BIT(0) /* 0-OD 1-PP */
> +#define STMFX_REG_IRQ_OUT_PIN_POL	BIT(1) /* 0-active LOW 1-active HIGH */
> +
> +/* STMFX_REG_IRQ_(SRC_EN/PENDING/ACK) bit shift */
> +enum stmfx_irqs {
> +	STMFX_REG_IRQ_SRC_EN_GPIO = 0,
> +	STMFX_REG_IRQ_SRC_EN_IDD,
> +	STMFX_REG_IRQ_SRC_EN_ERROR,
> +	STMFX_REG_IRQ_SRC_EN_TS_DET,
> +	STMFX_REG_IRQ_SRC_EN_TS_NE,
> +	STMFX_REG_IRQ_SRC_EN_TS_TH,
> +	STMFX_REG_IRQ_SRC_EN_TS_FULL,
> +	STMFX_REG_IRQ_SRC_EN_TS_OVF,
> +	STMFX_REG_IRQ_SRC_MAX,
> +};

I'd prefer from here up to the includes to be placed into the header.

> +/**
> + * struct stmfx_ddata - STMFX MFD private structure

You can drop '_ddata' from here (read next comment).

> + * @stmfx:		state holder with device for logs and register map

I don't understand why this requires an additional struct.

> + * @vdd:		STMFX power supply
> + * @irq_domain:		IRQ domain
> + * @lock:		IRQ bus lock
> + * @irq_src:		cache of IRQ_SRC_EN register for bus_lock
> + * @bkp_sysctrl:	backup of SYS_CTRL register for suspend/resume
> + * @bkp_irqoutpin:	backup of IRQ_OUT_PIN register for suspend/resume
> + */
> +struct stmfx_ddata {
> +	struct stmfx *stmfx;
> +	struct regulator *vdd;
> +	struct irq_domain *irq_domain;
> +	struct mutex lock; /* IRQ bus lock */
> +	u8 irq_src;
> +#ifdef CONFIG_PM
> +	u8 bkp_sysctrl;
> +	u8 bkp_irqoutpin;
> +#endif

I haven't seen this before.

Why is this necessary for *this* device and no others?

> +};
> +
> +static u8 stmfx_func_to_mask(u32 func)
> +{
> +	u8 mask = 0;
> +
> +	if (func & STMFX_FUNC_GPIO)
> +		mask |= STMFX_REG_SYS_CTRL_GPIO_EN;
> +
> +	if ((func & STMFX_FUNC_ALTGPIO_LOW) || (func & STMFX_FUNC_ALTGPIO_HIGH))
> +		mask |= STMFX_REG_SYS_CTRL_ALTGPIO_EN;
> +
> +	if (func & STMFX_FUNC_TS)
> +		mask |= STMFX_REG_SYS_CTRL_TS_EN;
> +
> +	if (func & STMFX_FUNC_IDD)
> +		mask |= STMFX_REG_SYS_CTRL_IDD_EN;
> +
> +	return mask;
> +}
> +
> +int stmfx_function_enable(struct stmfx *stmfx, u32 func)
> +{
> +	u32 sys_ctrl;
> +	u8 mask;
> +	int ret;
> +
> +	ret = regmap_read(stmfx->map, STMFX_REG_SYS_CTRL, &sys_ctrl);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * IDD and TS have priority in STMFX FW, so if IDD and TS are enabled,
> +	 * ALTGPIO function is disabled by STMFX FW. If IDD or TS is enabled,
> +	 * the number of aGPIO available decreases. To avoid GPIO management
> +	 * disturbance, abort IDD or TS function enable in this case.
> +	 */
> +	if (((func & STMFX_FUNC_IDD) || (func & STMFX_FUNC_TS)) &&
> +	    (sys_ctrl & STMFX_REG_SYS_CTRL_ALTGPIO_EN)) {
> +		dev_err(stmfx->dev, "ALTGPIO function already enabled\n");
> +		return -EBUSY;
> +	}
> +
> +	/* If TS is enabled, aGPIO[3:0] cannot be used */
> +	if ((func & STMFX_FUNC_ALTGPIO_LOW) &&
> +	    (sys_ctrl & STMFX_REG_SYS_CTRL_TS_EN)) {
> +		dev_err(stmfx->dev, "TS in use, aGPIO[3:0] unavailable\n");
> +		return -EBUSY;
> +	}
> +
> +	/* If IDD is enabled, aGPIO[7:4] cannot be used */
> +	if ((func & STMFX_FUNC_ALTGPIO_HIGH) &&
> +	    (sys_ctrl & STMFX_REG_SYS_CTRL_IDD_EN)) {
> +		dev_err(stmfx->dev, "IDD in use, aGPIO[7:4] unavailable\n");
> +		return -EBUSY;
> +	}
> +
> +	mask = stmfx_func_to_mask(func);
> +
> +	return regmap_update_bits(stmfx->map, STMFX_REG_SYS_CTRL, mask, mask);
> +}
> +EXPORT_SYMBOL_GPL(stmfx_function_enable);
> +
> +int stmfx_function_disable(struct stmfx *stmfx, u32 func)
> +{
> +	u8 mask = stmfx_func_to_mask(func);
> +
> +	return regmap_update_bits(stmfx->map, STMFX_REG_SYS_CTRL, mask, 0);
> +}
> +EXPORT_SYMBOL_GPL(stmfx_function_disable);
> +
> +static void stmfx_irq_bus_lock(struct irq_data *data)
> +{
> +	struct stmfx_ddata *ddata = irq_data_get_irq_chip_data(data);
> +
> +	mutex_lock(&ddata->lock);
> +}
> +
> +static void stmfx_irq_bus_sync_unlock(struct irq_data *data)
> +{
> +	struct stmfx_ddata *ddata = irq_data_get_irq_chip_data(data);
> +
> +	regmap_write(ddata->stmfx->map, STMFX_REG_IRQ_SRC_EN, ddata->irq_src);
> +
> +	mutex_unlock(&ddata->lock);
> +}
> +
> +static void stmfx_irq_mask(struct irq_data *data)
> +{
> +	struct stmfx_ddata *ddata = irq_data_get_irq_chip_data(data);
> +
> +	ddata->irq_src &= ~BIT(data->hwirq % 8);
> +}
> +
> +static void stmfx_irq_unmask(struct irq_data *data)
> +{
> +	struct stmfx_ddata *ddata = irq_data_get_irq_chip_data(data);
> +
> +	ddata->irq_src |= BIT(data->hwirq % 8);
> +}
> +
> +static struct irq_chip stmfx_irq_chip = {
> +	.name			= "stmfx-core",
> +	.irq_bus_lock		= stmfx_irq_bus_lock,
> +	.irq_bus_sync_unlock	= stmfx_irq_bus_sync_unlock,
> +	.irq_mask		= stmfx_irq_mask,
> +	.irq_unmask		= stmfx_irq_unmask,
> +};
> +
> +static irqreturn_t stmfx_irq_handler(int irq, void *data)
> +{
> +	struct stmfx_ddata *ddata = data;
> +	unsigned long n, pending;
> +	u32 ack;
> +	int ret;
> +
> +	ret = regmap_read(ddata->stmfx->map, STMFX_REG_IRQ_PENDING,
> +			  (u32 *)&pending);
> +	if (ret)
> +		return IRQ_NONE;
> +
> +	/*
> +	 * There is no ACK for GPIO, MFX_REG_IRQ_PENDING_GPIO is a logical OR
> +	 * of MFX_REG_IRQ_GPI _PENDING1/_PENDING2/_PENDING3
> +	 */
> +	ack = pending & ~BIT(STMFX_REG_IRQ_SRC_EN_GPIO);
> +	if (ack) {
> +		ret = regmap_write(ddata->stmfx->map, STMFX_REG_IRQ_ACK, ack);
> +		if (ret)
> +			return IRQ_NONE;
> +	}
> +
> +	for_each_set_bit(n, &pending, STMFX_REG_IRQ_SRC_MAX)
> +		handle_nested_irq(irq_find_mapping(ddata->irq_domain, n));
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int stmfx_irq_map(struct irq_domain *d, unsigned int virq,
> +			 irq_hw_number_t hwirq)
> +{
> +	irq_set_chip_data(virq, d->host_data);
> +	irq_set_chip_and_handler(virq, &stmfx_irq_chip, handle_simple_irq);
> +	irq_set_nested_thread(virq, 1);
> +	irq_set_noprobe(virq);
> +
> +	return 0;
> +}
> +
> +static void stmfx_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 stmfx_irq_ops = {
> +	.map	= stmfx_irq_map,
> +	.unmap	= stmfx_irq_unmap,
> +};
> +
> +static void stmfx_irq_exit(struct stmfx_ddata *ddata)
> +{
> +	int hwirq;
> +
> +	for (hwirq = 0; hwirq < STMFX_REG_IRQ_SRC_MAX; hwirq++)
> +		irq_dispose_mapping(irq_find_mapping(ddata->irq_domain, hwirq));

'\n' here please.

> +	irq_domain_remove(ddata->irq_domain);
> +}
> +
> +static int stmfx_irq_init(struct stmfx_ddata *ddata, int irq)
> +{
> +	struct device *dev = ddata->stmfx->dev;

Better to pass either 'dev' or 'pdev' around and extrapolate using the
dev_get_drvdata() helpers, rather than the other way around.

> +	u32 irqoutpin = 0, irqtrigger;
> +	int ret;
> +
> +	ddata->irq_domain = irq_domain_add_simple(dev->of_node,
> +						  STMFX_REG_IRQ_SRC_MAX, 0,
> +						  &stmfx_irq_ops, ddata);
> +	if (!ddata->irq_domain) {
> +		dev_err(dev, "failed to create irq domain\n");

s/irq/IRQ/

I also prefer capital letters to start sentences, but it's not
critical here.

> +		return -EINVAL;
> +	}
> +
> +	if (!of_property_read_bool(dev->of_node, "drive-open-drain"))
> +		irqoutpin |= STMFX_REG_IRQ_OUT_PIN_TYPE;
> +
> +	irqtrigger = irq_get_trigger_type(irq);
> +	if ((irqtrigger & IRQ_TYPE_EDGE_RISING) ||
> +	    (irqtrigger & IRQ_TYPE_LEVEL_HIGH))
> +		irqoutpin |= STMFX_REG_IRQ_OUT_PIN_POL;
> +
> +	ret = regmap_write(ddata->stmfx->map, STMFX_REG_IRQ_OUT_PIN, irqoutpin);
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_request_threaded_irq(dev, irq, NULL, stmfx_irq_handler,
> +					irqtrigger | IRQF_ONESHOT,
> +					"stmfx", ddata);
> +	if (ret)
> +		stmfx_irq_exit(ddata);
> +
> +	return ret;
> +}
> +
> +static int stmfx_chip_reset(struct stmfx_ddata *ddata)
> +{
> +	int ret;
> +
> +	ret = regmap_write(ddata->stmfx->map, STMFX_REG_SYS_CTRL,
> +			   STMFX_REG_SYS_CTRL_SWRST);
> +	if (ret)
> +		return ret;
> +
> +	msleep(STMFX_BOOT_TIME_MS);
> +
> +	return ret;
> +}
> +
> +static int stmfx_chip_init(struct stmfx_ddata *ddata, struct i2c_client *client)

No need to provide both ddata and client, you can extrapolate the
former from the latter.

> +{
> +	u32 id;
> +	u8 version[2];
> +	int ret;
> +
> +	ddata->vdd = devm_regulator_get_optional(&client->dev, "vdd");
> +	if (IS_ERR(ddata->vdd)) {
> +		ret = PTR_ERR(ddata->vdd);
> +		if (ret != -ENODEV) {
> +			if (ret != -EPROBE_DEFER)
> +				dev_err(&client->dev,
> +					"no vdd regulator found:%d\n", ret);

s/vdd/VDD/?

> +			return ret;
> +		}
> +	}
> +
> +	if (!IS_ERR(ddata->vdd)) {

Why not just 'else'?

> +		ret = regulator_enable(ddata->vdd);
> +		if (ret) {
> +			dev_err(&client->dev, "vdd enable failed: %d\n", ret);

s/vdd/VDD/?

> +			return ret;
> +		}
> +	}
> +
> +	ret = regmap_read(ddata->stmfx->map, STMFX_REG_CHIP_ID, &id);
> +	if (ret) {
> +		dev_err(&client->dev, "error reading chip id: %d\n", ret);

s/id/ID/

> +		goto err;
> +	}
> +
> +	/*
> +	 * Check that ID is the complement of the I2C address:
> +	 * STMFX I2C address follows the 7-bit format (MSB), that's why
> +	 * client->addr is shifted.
> +	 *
> +	 * STMFX_I2C_ADDR|       STMFX         |        Linux
> +	 *   input pin   | I2C device address  | I2C device address
> +	 *---------------------------------------------------------
> +	 *       0       | b: 1000 010x h:0x84 |       0x42
> +	 *       1       | b: 1000 011x h:0x86 |       0x43
> +	 */
> +	if (FIELD_GET(STMFX_REG_CHIP_ID_MASK, ~id) != (client->addr << 1)) {
> +		dev_err(&client->dev, "unknown chip id: %#x\n", id);
> +		ret = -EINVAL;
> +		goto err;
> +	}
> +
> +	ret = regmap_bulk_read(ddata->stmfx->map, STMFX_REG_FW_VERSION_MSB,
> +			       version, ARRAY_SIZE(version));
> +	if (ret) {
> +		dev_err(&client->dev, "error reading fw version: %d\n", ret);
> +		goto err;
> +	}
> +
> +	dev_info(&client->dev, "STMFX id: %#x, fw version: %x.%02x\n",
> +		 id, version[0], version[1]);
> +
> +	return stmfx_chip_reset(ddata);
> +
> +err:
> +	if (!IS_ERR(ddata->vdd))
> +		return regulator_disable(ddata->vdd);
> +
> +	return ret;
> +}
> +
> +static int stmfx_chip_exit(struct stmfx_ddata *ddata)
> +{
> +	regmap_write(ddata->stmfx->map, STMFX_REG_IRQ_SRC_EN, 0);
> +	regmap_write(ddata->stmfx->map, STMFX_REG_SYS_CTRL, 0);
> +
> +	if (!IS_ERR(ddata->vdd))
> +		return regulator_disable(ddata->vdd);
> +
> +	return 0;
> +}
> +
> +static const struct resource stmfx_pinctrl_resources[] = {
> +	DEFINE_RES_IRQ(STMFX_REG_IRQ_SRC_EN_GPIO),
> +};
> +
> +static struct mfd_cell stmfx_cells[] = {
> +	{
> +		.of_compatible = "st,stmfx-0300-pinctrl",
> +		.name = "stmfx-pinctrl",
> +		.resources = stmfx_pinctrl_resources,
> +		.num_resources = ARRAY_SIZE(stmfx_pinctrl_resources),
> +	}
> +};

What other devices make up this MFD?

> +static bool stmfx_reg_volatile(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case STMFX_REG_SYS_CTRL:
> +	case STMFX_REG_IRQ_SRC_EN:
> +	case STMFX_REG_IRQ_PENDING:
> +	case STMFX_REG_IRQ_GPI_PENDING1:
> +	case STMFX_REG_IRQ_GPI_PENDING2:
> +	case STMFX_REG_IRQ_GPI_PENDING3:
> +	case STMFX_REG_GPIO_STATE1:
> +	case STMFX_REG_GPIO_STATE2:
> +	case STMFX_REG_GPIO_STATE3:
> +	case STMFX_REG_IRQ_GPI_SRC1:
> +	case STMFX_REG_IRQ_GPI_SRC2:
> +	case STMFX_REG_IRQ_GPI_SRC3:
> +	case STMFX_REG_GPO_SET1:
> +	case STMFX_REG_GPO_SET2:
> +	case STMFX_REG_GPO_SET3:
> +	case STMFX_REG_GPO_CLR1:
> +	case STMFX_REG_GPO_CLR2:
> +	case STMFX_REG_GPO_CLR3:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static bool stmfx_reg_writeable(struct device *dev, unsigned int reg)
> +{
> +	return (reg >= STMFX_REG_SYS_CTRL);
> +}
> +
> +static const struct regmap_config stmfx_regmap_config = {
> +	.reg_bits	= 8,
> +	.reg_stride	= 1,
> +	.val_bits	= 8,
> +	.max_register	= STMFX_REG_MAX,
> +	.volatile_reg	= stmfx_reg_volatile,
> +	.writeable_reg	= stmfx_reg_writeable,
> +	.cache_type	= REGCACHE_RBTREE,
> +};
> +
> +static int stmfx_probe(struct i2c_client *client,
> +		       const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct stmfx_ddata *ddata;
> +	int i, ret;
> +
> +	ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
> +	if (!ddata)
> +		return -ENOMEM;

'\n' here please.

> +	/* State holder */
> +	ddata->stmfx = devm_kzalloc(dev, sizeof(*ddata->stmfx), GFP_KERNEL);
> +	if (!ddata->stmfx)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, ddata);
> +
> +	ddata->stmfx->dev = dev;
> +
> +	ddata->stmfx->map = devm_regmap_init_i2c(client, &stmfx_regmap_config);

Just put this straight into the parent struct and do away with the
extra complication.

> +	if (IS_ERR(ddata->stmfx->map)) {
> +		ret = PTR_ERR(ddata->stmfx->map);
> +		dev_err(dev, "failed to allocate register map: %d\n", ret);
> +		return ret;
> +	}
> +
> +	mutex_init(&ddata->lock);
> +
> +	ret = stmfx_chip_init(ddata, client);
> +	if (ret) {
> +		if (ret == -ETIMEDOUT)
> +			return -EPROBE_DEFER;
> +		return ret;
> +	}
> +
> +	if (client->irq < 0) {
> +		dev_err(dev, "failed to get irq: %d\n", client->irq);
> +		ret = client->irq;
> +		goto err_chip_exit;
> +	}
> +
> +	ret = stmfx_irq_init(ddata, client->irq);
> +	if (ret)
> +		goto err_chip_exit;
> +
> +	for (i = 0; i < ARRAY_SIZE(stmfx_cells); i++) {
> +		stmfx_cells[i].platform_data = ddata->stmfx;
> +		stmfx_cells[i].pdata_size = sizeof(struct stmfx);
> +	}
> +
> +	ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> +				   stmfx_cells, ARRAY_SIZE(stmfx_cells), NULL,
> +				   0, ddata->irq_domain);
> +	if (ret)
> +		goto err_irq_exit;
> +
> +	return 0;
> +
> +err_irq_exit:
> +	stmfx_irq_exit(ddata);
> +err_chip_exit:
> +	stmfx_chip_exit(ddata);
> +
> +	return ret;
> +}
> +
> +static int stmfx_remove(struct i2c_client *client)
> +{
> +	struct stmfx_ddata *ddata = i2c_get_clientdata(client);
> +
> +	stmfx_irq_exit(ddata);
> +
> +	return stmfx_chip_exit(ddata);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int stmfx_backup_regs(struct stmfx_ddata *ddata)
> +{
> +	int ret;
> +
> +	ret = regmap_raw_read(ddata->stmfx->map, STMFX_REG_SYS_CTRL,
> +			      &ddata->bkp_sysctrl, sizeof(ddata->bkp_sysctrl));
> +	if (ret)
> +		return ret;
> +	ret = regmap_raw_read(ddata->stmfx->map, STMFX_REG_IRQ_OUT_PIN,
> +			      &ddata->bkp_irqoutpin,
> +			      sizeof(ddata->bkp_irqoutpin));
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int stmfx_restore_regs(struct stmfx_ddata *ddata)
> +{
> +	int ret;
> +
> +	ret = regmap_raw_write(ddata->stmfx->map, STMFX_REG_SYS_CTRL,
> +			       &ddata->bkp_sysctrl, sizeof(ddata->bkp_sysctrl));
> +	if (ret)
> +		return ret;
> +	ret = regmap_raw_write(ddata->stmfx->map, STMFX_REG_IRQ_OUT_PIN,
> +			       &ddata->bkp_irqoutpin,
> +			       sizeof(ddata->bkp_irqoutpin));
> +	if (ret)
> +		return ret;
> +	ret = regmap_raw_write(ddata->stmfx->map, STMFX_REG_IRQ_SRC_EN,
> +			       &ddata->irq_src, sizeof(ddata->irq_src));
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int stmfx_suspend(struct device *dev)
> +{
> +	struct stmfx_ddata *ddata = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = stmfx_backup_regs(ddata);
> +	if (ret) {
> +		dev_err(ddata->stmfx->dev, "registers backup failure\n");
> +		return ret;
> +	}
> +
> +	if (!IS_ERR(ddata->vdd)) {
> +		ret = regulator_disable(ddata->vdd);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int stmfx_resume(struct device *dev)
> +{
> +	struct stmfx_ddata *ddata = dev_get_drvdata(dev);
> +	int ret;
> +
> +	if (!IS_ERR(ddata->vdd)) {
> +		ret = regulator_enable(ddata->vdd);
> +		if (ret) {
> +			dev_err(ddata->stmfx->dev,
> +				"vdd enable failed: %d\n", ret);
> +			return ret;
> +		}
> +	}
> +
> +	ret = stmfx_restore_regs(ddata);
> +	if (ret) {
> +		dev_err(ddata->stmfx->dev, "registers restoration failure\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(stmfx_dev_pm_ops, stmfx_suspend, stmfx_resume);
> +
> +static const struct of_device_id stmfx_of_match[] = {
> +	{ .compatible = "st,stmfx-0300", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, stmfx_of_match);
> +
> +static struct i2c_driver stmfx_driver = {
> +	.driver = {
> +		.name = "stmfx-core",
> +		.of_match_table = of_match_ptr(stmfx_of_match),
> +		.pm = &stmfx_dev_pm_ops,
> +	},
> +	.probe = stmfx_probe,
> +	.remove = stmfx_remove,
> +};
> +module_i2c_driver(stmfx_driver);
> +
> +MODULE_DESCRIPTION("STMFX core driver");
> +MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@...com>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/stmfx.h b/include/linux/mfd/stmfx.h
> new file mode 100644
> index 0000000..35c3d42
> --- /dev/null
> +++ b/include/linux/mfd/stmfx.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2018 STMicroelectronics
> + * Author(s): Amelie Delaunay <amelie.delaunay@...com>.
> + */
> +
> +#ifndef MFD_STMFX_H
> +#define MFX_STMFX_H
> +
> +#include <linux/regmap.h>
> +
> +enum stmfx_functions {
> +	STMFX_FUNC_GPIO		= BIT(0), /* GPIO[15:0] */
> +	STMFX_FUNC_ALTGPIO_LOW	= BIT(1), /* aGPIO[3:0] */
> +	STMFX_FUNC_ALTGPIO_HIGH = BIT(2), /* aGPIO[7:4] */
> +	STMFX_FUNC_TS		= BIT(3),
> +	STMFX_FUNC_IDD		= BIT(4),
> +};
> +
> +struct stmfx {
> +	struct device *dev;
> +	struct regmap *map;
> +};
> +
> +int stmfx_function_enable(struct stmfx *stmfx, u32 func);
> +int stmfx_function_disable(struct stmfx *stmfx, u32 func);
> +#endif

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