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    SubjectRe: [PATCH v8 8/9] mfd: smpro-mfd: Adds Ampere's Altra SMpro MFD driver
    On Fri, 22 Apr 2022, Quan Nguyen wrote:

    > Adds Multi-function devices driver for SMpro co-processor found on the

    Please drop the term MFD and describe the device instead.

    > Mt.Jade hardware reference platform with Ampere's Altra processor family.
    >
    > Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
    > ---
    > Changes in v8:
    > + None
    >
    > Changes in v7:
    > + Smpro-mfd now significant changes in compare with simple-mfd-i2c
    > driver, remove the copyright note about simple-mfd-i2c [Quan]
    > + Install bus->read/write() to handle multiple types of bus
    > access. [Quan]
    > + Update license to MODULE_LICENSE("GPL") [Quan]
    > + Add others minor refactor the code [Quan]
    >
    > Changes in v6:
    > + Update license part to reflect that this driver is clone from
    > simple-mfd-i2c driver [Quan]
    >
    > Changes in v5:
    > + Dropped the use of simple-mfd-i2c driver [Quan]
    > + Introduced drivers/mfd/smpro-mfd.c driver to instantiate
    > sub-devices. This is to avoid DT nodes without resource issue [Quan]
    > + Revised commit message [Quan]
    >
    > Changes in v4:
    > + Add "depends on I2C" to fix build issue found by kernel test
    > robot [Guenter]
    >
    > Changes in v3:
    > + None
    >
    > Changes in v2:
    > + Used 'struct of_device_id's .data attribute [Lee Jones]
    >
    > drivers/mfd/Kconfig | 12 ++++
    > drivers/mfd/Makefile | 1 +
    > drivers/mfd/smpro-mfd.c | 134 ++++++++++++++++++++++++++++++++++++++++

    Please drop the 'mfd' part. Does 'core' work instead?

    > 3 files changed, 147 insertions(+)
    > create mode 100644 drivers/mfd/smpro-mfd.c
    >
    > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
    > index 3b59456f5545..383d0e6cfb91 100644
    > --- a/drivers/mfd/Kconfig
    > +++ b/drivers/mfd/Kconfig
    > @@ -77,6 +77,18 @@ config MFD_AS3711
    > help
    > Support for the AS3711 PMIC from AMS
    >
    > +config MFD_SMPRO
    > + tristate "Ampere Computing MFD SMpro core driver"

    Drop 'MFD'.

    > + depends on I2C
    > + select MFD_CORE
    > + select REGMAP_I2C
    > + help
    > + Say yes here to enable SMpro driver support for Ampere's Altra
    > + processor family.
    > +
    > + Ampere's Altra SMpro exposes an I2C regmap interface that can
    > + be accessed by child devices.
    > +
    > config MFD_AS3722
    > tristate "ams AS3722 Power Management IC"
    > select MFD_CORE
    > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
    > index 858cacf659d6..36f8981cc4fd 100644
    > --- a/drivers/mfd/Makefile
    > +++ b/drivers/mfd/Makefile
    > @@ -266,6 +266,7 @@ obj-$(CONFIG_MFD_QCOM_PM8008) += qcom-pm8008.o
    >
    > obj-$(CONFIG_SGI_MFD_IOC3) += ioc3.o
    > obj-$(CONFIG_MFD_SIMPLE_MFD_I2C) += simple-mfd-i2c.o
    > +obj-$(CONFIG_MFD_SMPRO) += smpro-mfd.o
    > obj-$(CONFIG_MFD_INTEL_M10_BMC) += intel-m10-bmc.o
    >
    > obj-$(CONFIG_MFD_ATC260X) += atc260x-core.o
    > diff --git a/drivers/mfd/smpro-mfd.c b/drivers/mfd/smpro-mfd.c
    > new file mode 100644
    > index 000000000000..485c4f89ebd9
    > --- /dev/null
    > +++ b/drivers/mfd/smpro-mfd.c
    > @@ -0,0 +1,134 @@
    > +// SPDX-License-Identifier: GPL-2.0-only
    > +/*
    > + * Ampere Altra Family SMPro MFD - I2C

    Drop 'MFD' throughout.

    > + * Copyright (c) 2022, Ampere Computing LLC
    > + * Author: Quan Nguyen <quan@os.amperecomputing..com>
    > + */
    > +
    > +#include <linux/i2c.h>
    > +#include <linux/kernel.h>
    > +#include <linux/module.h>
    > +#include <linux/of_platform.h>
    > +#include <linux/mfd/core.h>
    > +#include <linux/regmap.h>

    Alphabetical.

    > +/* Identification Registers */
    > +#define MANUFACTURER_ID_REG 0x02
    > +#define AMPERE_MANUFACTURER_ID 0xCD3A
    > +
    > +static int smpro_mfd_write(void *context, const void *data, size_t count)
    > +{
    > + struct device *dev = context;
    > + struct i2c_client *i2c = to_i2c_client(dev);
    > + int ret;
    > +
    > + ret = i2c_master_send(i2c, data, count);
    > + if (ret == count)
    > + return 0;
    > + else if (ret < 0)
    > + return ret;
    > + else
    > + return -EIO;
    > +}
    > +
    > +static int smpro_mfd_read(void *context, const void *reg, size_t reg_size,
    > + void *val, size_t val_size)
    > +{
    > + struct device *dev = context;
    > + struct i2c_client *i2c = to_i2c_client(dev);
    > + struct i2c_msg xfer[2];
    > + unsigned char buf[2];
    > + int ret;
    > +
    > + xfer[0].addr = i2c->addr;
    > + xfer[0].flags = 0;
    > +
    > + buf[0] = *(u8 *)reg;
    > + buf[1] = val_size;
    > + xfer[0].len = 2;
    > + xfer[0].buf = buf;
    > +
    > + xfer[1].addr = i2c->addr;
    > + xfer[1].flags = I2C_M_RD;
    > + xfer[1].len = val_size;
    > + xfer[1].buf = val;
    > +
    > + ret = i2c_transfer(i2c->adapter, xfer, 2);
    > + if (ret == 2)
    > + return 0;
    > + else if (ret < 0)
    > + return ret;
    > + else
    > + return -EIO;
    > +}

    This looks all too familiar.

    I wonder how generic these i2c call-backs actually are.

    > +static const struct regmap_bus smpro_regmap_bus = {
    > + .read = smpro_mfd_read,
    > + .write = smpro_mfd_write,
    > + .val_format_endian_default = REGMAP_ENDIAN_BIG,
    > +};
    > +
    > +static bool smpro_mfd_readable_noinc_reg(struct device *dev, unsigned int reg)
    > +{
    > + return (reg == 0x82 || reg == 0x85 || reg == 0x92 || reg == 0x95 ||
    > + reg == 0xC2 || reg == 0xC5 || reg == 0xD2 || reg == 0xDA);

    No magic numbers. Please define these registers.

    > +}
    > +
    > +static const struct regmap_config smpro_regmap_config = {
    > + .reg_bits = 8,
    > + .val_bits = 16,
    > + .readable_noinc_reg = smpro_mfd_readable_noinc_reg,
    > +};
    > +
    > +static const struct mfd_cell smpro_devs[] = {
    > + MFD_CELL_NAME("smpro-hwmon"),
    > + MFD_CELL_NAME("smpro-errmon"),
    > + MFD_CELL_NAME("smpro-misc"),
    > +};
    > +
    > +static int smpro_mfd_probe(struct i2c_client *i2c)
    > +{
    > + const struct regmap_config *config;
    > + struct regmap *regmap;
    > + unsigned int val;
    > + int ret;
    > +
    > + config = device_get_match_data(&i2c->dev);
    > + if (!config)
    > + config = &smpro_regmap_config;

    This use-case is not currently supported.

    Please return an error instead.

    > + regmap = devm_regmap_init(&i2c->dev, &smpro_regmap_bus, &i2c->dev, config);
    > + if (IS_ERR(regmap))
    > + return PTR_ERR(regmap);
    > +
    > + /* Check for valid ID */

    Decent #define nomenclature should render this comment superfluous.

    > + ret = regmap_read(regmap, MANUFACTURER_ID_REG, &val);
    > + if (ret)
    > + return ret;
    > +
    > + if (val != AMPERE_MANUFACTURER_ID)
    > + return -ENODEV;
    > +
    > + return devm_mfd_add_devices(&i2c->dev, PLATFORM_DEVID_AUTO,
    > + smpro_devs, ARRAY_SIZE(smpro_devs), NULL, 0, NULL);
    > +}
    > +
    > +static const struct of_device_id smpro_mfd_of_match[] = {
    > + { .compatible = "ampere,smpro", .data = &smpro_regmap_config },
    > + {}
    > +};
    > +MODULE_DEVICE_TABLE(of, smpro_mfd_of_match);
    > +
    > +static struct i2c_driver smpro_mfd_driver = {
    > + .probe_new = smpro_mfd_probe,
    > + .driver = {
    > + .name = "smpro-mfd-i2c",

    "smpro-core"

    > + .of_match_table = smpro_mfd_of_match,
    > + },
    > +};
    > +module_i2c_driver(smpro_mfd_driver);
    > +
    > +MODULE_AUTHOR("Quan Nguyen <quan@os.amperecomputing.com>");
    > +MODULE_DESCRIPTION("SMPRO MFD - I2C driver");
    > +MODULE_LICENSE("GPL");

    --
    Lee Jones [李琼斯]
    Principal Technical Lead - Developer Services
    Linaro.org │ Open source software for Arm SoCs
    Follow Linaro: Facebook | Twitter | Blog

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