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SubjectRe: [RFC 2/6] mfd: Support for Ettus Research E31x devices PMU
On Mon, 11 Feb 2019, Virendra Kakade wrote:

> Signed-off-by: Virendra Kakade <virendra.kakade@ni.com>
> ---
> drivers/mfd/Kconfig | 7 +++
> drivers/mfd/Makefile | 2 +-
> drivers/mfd/e31x-pmu.c | 89 ++++++++++++++++++++++++++++++++++++
> include/linux/mfd/e31x-pmu.h | 20 ++++++++
> 4 files changed, 117 insertions(+), 1 deletion(-)
> create mode 100644 drivers/mfd/e31x-pmu.c
> create mode 100644 include/linux/mfd/e31x-pmu.h
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 8c5dfdce4326..6c4c0747f2a5 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1916,4 +1916,11 @@ config RAVE_SP_CORE
> device found on several devices in RAVE line of hardware.
>
> endmenu
> +
> +config MFD_E31X_PMU
> + tristate "E31X PMU driver"
> + select MFD_SYSCON
> + help
> + Select this to get support for the Ettus Research E31x devices.
> +
> endif
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 12980a4ad460..e37c2057134b 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -241,4 +241,4 @@ 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_E31X_PMU) += e31x-pmu.o
> diff --git a/drivers/mfd/e31x-pmu.c b/drivers/mfd/e31x-pmu.c
> new file mode 100644
> index 000000000000..383df68a538f
> --- /dev/null
> +++ b/drivers/mfd/e31x-pmu.c
> @@ -0,0 +1,89 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018 National Instruments Corp

This is out of date.

'\n' here.

> + * Author: Virendra Kakade<virendra.kakade@ni.com>

You need a space after your name.

> + * Ettus Research E31x PMU MFD driver

Please expand PMU.

> + */
> +
> +#include <linux/err.h>
> +#include <linux/delay.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/core.h>
> +#include <linux/of_device.h>
> +#include <linux/mfd/e31x-pmu.h>
> +#include <linux/platform_device.h>

Alphabetical.

> +#define E31X_PMU_MISC_IRQ_MASK BIT(8)
> +#define E31X_PMU_MISC_IRQ_SHIFT 8
> +#define E31X_PMU_MISC_VERSION_MIN_MASK GENMASK(3, 0)
> +#define E31X_PMU_MISC_VERSION_MIN_SHIFT 0
> +#define E31X_PMU_MISC_VERSION_MAJ_MASK GENMASK(7, 4)
> +#define E31X_PMU_MISC_VERSION_MAJ_SHIFT 4
> +
> +struct e31x_pmu {
> + struct regmap *regmap;
> +};

A whole struct for one attribute?

> +static int e31x_pmu_check_version(struct e31x_pmu *pmu)
> +{
> + int timeout = 100;

Where does 100 come from?

> + u32 misc, maj;
> + int err;

'ret' is more common.

> + /* we need to wait a bit for firmware to populate the fields */

"a bit" ?

What does the datasheet say?

Please use proper grammar. Capital letters.

> + while (timeout--) {
> + err = regmap_read(pmu->regmap, E31X_PMU_REG_MISC, &misc);
> + if (err)
> + return err;
> + if (misc)
> + break;
> +
> + usleep_range(2500, 5000);

Formatting.

> + }
> +
> + /* only firmware versions above 2.0 are supported */

"Only supports firmware version 2.0 and above"

> + maj = E31X_PMU_GET_FIELD(MISC_VERSION_MAJ, misc);
> + if (maj < 2)
> + return -ENOTSUPP;

'\n' here.

> + return 0;
> +}
> +
> +static int e31x_pmu_probe(struct platform_device *pdev)
> +{
> + struct e31x_pmu *pmu;
> +
> + pmu = devm_kzalloc(&pdev->dev, sizeof(*pmu), GFP_KERNEL);
> + if (!pmu)
> + return -ENOMEM;

'\n' here.

> + pmu->regmap = syscon_regmap_lookup_by_phandle(\

Why are you storing regmap?

Just pass it directly to e31x_pmu_check_version().

> + pdev->dev.of_node, "regmap");
> +

Remove this line.

> + if (IS_ERR(pmu->regmap))
> + return PTR_ERR(pmu->regmap);

'\n' here.

> + if (e31x_pmu_check_version(pmu))

Please split out the function from the if.

Use a variable 'ret' to feed into and check that.

> + return -ENOTSUPP;

'\n' here.

> + return devm_of_platform_populate(&pdev->dev);
> +}
> +
> +static const struct of_device_id e31x_pmu_id[] = {
> + { .compatible = "ni,e31x-pmu" },
> + {},
> +};
> +
> +static struct platform_driver e31x_pmu_driver = {
> + .driver = {
> + .name = "e31x-pmu",
> + .of_match_table = e31x_pmu_id,

These 2 lines need indenting.

> + },
> + .probe = e31x_pmu_probe,
> +};
> +module_platform_driver(e31x_pmu_driver);
> +
> +MODULE_DESCRIPTION("E31x PMU driver");
> +MODULE_AUTHOR("Virendra Kakade <virendra.kakade@ni.com>");
> +MODULE_LICENSE("GPL");

So the whole purpose of this driver is to do a version check.

Seems like over-kill!

Probably better to do the version check in an inline function stored
in a header file, then call it from each of the children's .probe()
function.

> diff --git a/include/linux/mfd/e31x-pmu.h b/include/linux/mfd/e31x-pmu.h
> new file mode 100644
> index 000000000000..c57d5a8c1aad
> --- /dev/null
> +++ b/include/linux/mfd/e31x-pmu.h
> @@ -0,0 +1,20 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018 National Instruments Corp

Out of date.

'\n' here.

> + * Author: Virendra Kakade <virendra.kakade@ni.com>
> + *
> + * Ettus Research E31x PMU constants
> + */
> +
> +#ifndef MFD_E31X_PMU_H
> +#define MFD_E31X_PMU_H
> +
> +#include <linux/bitops.h>
> +
> +#define E31X_PMU_REG_MISC 0x04
> +
> +#define E31X_PMU_GET_FIELD(name, reg) \
> + (((reg) & E31X_PMU_## name ##_MASK) >> \
> + E31X_PMU_## name ##_SHIFT)
> +
> +#endif /* MFD_E31X_PMU_H */

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