Re: [PATCH v5 2/9] mfd: Add ST Multi-Function eXpander (STMFX) core driver

[Amelie DELAUNAY <amelie.delaunay@xxxxxx>]

On 5/8/19 10:36 AM, Lee Jones wrote:
> On Tue, 09 Apr 2019, 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@xxxxxx>
>> ---
>>   drivers/mfd/Kconfig       |  13 ++
>>   drivers/mfd/Makefile      |   2 +-
>>   drivers/mfd/stmfx.c       | 566 ++++++++++++++++++++++++++++++++++++++++++++++
>>   include/linux/mfd/stmfx.h | 123 ++++++++++
>>   4 files changed, 703 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 3443f1a..9783e18 100644
>> --- a/drivers/mfd/Kconfig
>> +++ b/drivers/mfd/Kconfig
>> @@ -1907,6 +1907,19 @@ config MFD_STPMIC1
>>   	  To compile this driver as a module, choose M here: the
>>   	  module will be called stpmic1.
>>   
>> +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 b4569ed7..614eea8 100644
>> --- a/drivers/mfd/Makefile
>> +++ b/drivers/mfd/Makefile
>> @@ -246,4 +246,4 @@ 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..59f0a03
>> --- /dev/null
>> +++ b/drivers/mfd/stmfx.c
>> @@ -0,0 +1,566 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Driver for STMicroelectronics Multi-Function eXpander (STMFX) core
>> + *
>> + * Copyright (C) 2019 STMicroelectronics
>> + * Author(s): Amelie Delaunay <amelie.delaunay@xxxxxx>.
>> + */
>> +#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>
> 
> [...]
> 
>> +static int stmfx_chip_init(struct i2c_client *client)
>> +{
>> +	struct stmfx *stmfx = i2c_get_clientdata(client);
>> +	u32 id;
>> +	u8 version[2];
>> +	int ret;
>> +
>> +	stmfx->vdd = devm_regulator_get_optional(&client->dev, "vdd");
>> +	if (IS_ERR(stmfx->vdd)) {
>> +		ret = PTR_ERR(stmfx->vdd);
>> +		if (ret != -ENODEV) {
>> +			if (ret != -EPROBE_DEFER)
>> +				dev_err(&client->dev,
>> +					"Can't get VDD regulator:%d\n", ret);
>> +			return ret;
>> +		}
> 
> Any reason you've decided to stick with this 3-layer nested if instead
> of going with my suggestion?
> 

Sorry, I didn't see your suggestion. I'll go with it in v6.

>> +	} else {
>> +		ret = regulator_enable(stmfx->vdd);
>> +		if (ret) {
>> +			dev_err(&client->dev, "VDD enable failed: %d\n", ret);
>> +			return ret;
>> +		}
>> +	}
> 
> [...]
> 
>> +#ifdef CONFIG_PM_SLEEP
>> +static int stmfx_backup_regs(struct stmfx *stmfx)
>> +{
>> +	int ret;
>> +
>> +	ret = regmap_raw_read(stmfx->map, STMFX_REG_SYS_CTRL,
>> +			      &stmfx->bkp_sysctrl, sizeof(stmfx->bkp_sysctrl));
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = regmap_raw_read(stmfx->map, STMFX_REG_IRQ_OUT_PIN,
>> +			      &stmfx->bkp_irqoutpin,
>> +			      sizeof(stmfx->bkp_irqoutpin));
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int stmfx_restore_regs(struct stmfx *stmfx)
>> +{
>> +	int ret;
>> +
>> +	ret = regmap_raw_write(stmfx->map, STMFX_REG_SYS_CTRL,
>> +			       &stmfx->bkp_sysctrl, sizeof(stmfx->bkp_sysctrl));
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = regmap_raw_write(stmfx->map, STMFX_REG_IRQ_OUT_PIN,
>> +			       &stmfx->bkp_irqoutpin,
>> +			       sizeof(stmfx->bkp_irqoutpin));
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = regmap_raw_write(stmfx->map, STMFX_REG_IRQ_SRC_EN,
>> +			       &stmfx->irq_src, sizeof(stmfx->irq_src));
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int stmfx_suspend(struct device *dev)
>> +{
>> +	struct stmfx *stmfx = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	ret = stmfx_backup_regs(stmfx);
>> +	if (ret) {
>> +		dev_err(stmfx->dev, "Registers backup failure\n");
>> +		return ret;
>> +	}
> 
> This doesn't need to be an extra function.  You're just adding more
> lines of code for no real gain in reusability/readability.
> 

I used a separate function to have only one dev_err in case of 
backup/restore failure.
But anyway, I'll drop backup/restore functions and put the code in 
suspend/resume.

>> +	if (!IS_ERR(stmfx->vdd)) {
>> +		ret = regulator_disable(stmfx->vdd);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int stmfx_resume(struct device *dev)
>> +{
>> +	struct stmfx *stmfx = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	if (!IS_ERR(stmfx->vdd)) {
>> +		ret = regulator_enable(stmfx->vdd);
>> +		if (ret) {
>> +			dev_err(stmfx->dev,
>> +				"VDD enable failed: %d\n", ret);
>> +			return ret;
>> +		}
>> +	}
>> +
>> +	ret = stmfx_restore_regs(stmfx);
>> +	if (ret) {
>> +		dev_err(stmfx->dev, "Registers restoration failure\n");
>> +		return ret;
>> +	}
> 
> This doesn't need to be an extra function.  You're just adding more
> lines of code for no real gain in reusability/readability.
> 
>> +	return 0;
>> +}
>> +#endif
> 
> [...]
>