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Date: Wed, 16 Dec 2020 14:12:13 +0000
From: Lee Jones <lee.jones@...aro.org>
To: cy_huang <u0084500@...il.com>
Cc: robh+dt@...nel.org, cy_huang@...htek.com,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 1/3] mfd: rt4831: Adds support for Richtek RT4831 MFD
core
On Sat, 12 Dec 2020, cy_huang wrote:
> From: ChiYuan Huang <cy_huang@...htek.com>
>
> This adds support Richtek RT4831 MFD core. It includes four channel WLED driver
Drop mentions of MFD. Just core driver will do.
> and Display Bias Voltage outputs.
>
> Signed-off-by: ChiYuan Huang <cy_huang@...htek.com>
> ---
> since v2
> - Refine Kconfig descriptions.
> - Add copyright.
> - Refine error logs in probe.
> - Refine comment lines in remove and shutdown.
> ---
> drivers/mfd/Kconfig | 10 ++++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/rt4831-core.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 135 insertions(+)
> create mode 100644 drivers/mfd/rt4831-core.c
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 8b99a13..dfb2640 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -1088,6 +1088,16 @@ config MFD_RDC321X
> southbridge which provides access to GPIOs and Watchdog using the
> southbridge PCI device configuration space.
>
> +config MFD_RT4831
> + tristate "Richtek RT4831 four channel WLED and Display Bias Voltage"
> + depends on I2C
> + select MFD_CORE
> + select REGMAP_I2C
> + help
> + This enables support for the Richtek RT4831 that includes 4 channel
> + WLED driving and Display Bias Voltage. It's commonly used to provide
> + power to the LCD display and LCD backlight.
> +
> config MFD_RT5033
> tristate "Richtek RT5033 Power Management IC"
> depends on I2C
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 1780019..4108141 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -235,6 +235,7 @@ obj-$(CONFIG_MFD_MENF21BMC) += menf21bmc.o
> obj-$(CONFIG_MFD_HI6421_PMIC) += hi6421-pmic-core.o
> obj-$(CONFIG_MFD_HI655X_PMIC) += hi655x-pmic.o
> obj-$(CONFIG_MFD_DLN2) += dln2.o
> +obj-$(CONFIG_MFD_RT4831) += rt4831-core.o
Why is this called -core ...
> obj-$(CONFIG_MFD_RT5033) += rt5033.o
... and this isn't?
> obj-$(CONFIG_MFD_SKY81452) += sky81452.o
>
> diff --git a/drivers/mfd/rt4831-core.c b/drivers/mfd/rt4831-core.c
> new file mode 100644
> index 00000000..f837c06
> --- /dev/null
> +++ b/drivers/mfd/rt4831-core.c
> @@ -0,0 +1,124 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2020 Richtek Technology Corp.
> + *
> + * Author: ChiYuan Huang <cy_huang@...htek.com>
> + */
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/core.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#define RT4831_REG_REVISION 0x01
> +#define RT4831_REG_ENABLE 0x08
> +#define RT4831_REG_I2CPROT 0x15
> +
> +#define RICHTEK_VID 0x03
> +#define RT4831_VID_MASK GENMASK(1, 0)
> +#define RT4831_RESET_MASK BIT(7)
> +#define RT4831_I2CSAFETMR_MASK BIT(0)
> +
> +static const struct mfd_cell rt4831_subdevs[] = {
> + OF_MFD_CELL("rt4831-backlight", NULL, NULL, 0, 0, "richtek,rt4831-backlight"),
> + MFD_CELL_NAME("rt4831-regulator")
> +};
Just a little note about these helpers. I'm planning on unifying the
names pretty soon. So if you have to rebase, please watch out for the
rename.
Essentially OF_MFD_CELL() will soon become MFD_CELL_OF().
> +static bool rt4831_is_accessible_reg(struct device *dev, unsigned int reg)
> +{
> + if (reg >= RT4831_REG_REVISION && reg <= RT4831_REG_I2CPROT)
> + return true;
> + return false;
> +}
> +
> +static const struct regmap_config rt4831_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> + .max_register = RT4831_REG_I2CPROT,
> +
> + .readable_reg = rt4831_is_accessible_reg,
> + .writeable_reg = rt4831_is_accessible_reg,
> +};
> +
> +static int rt4831_probe(struct i2c_client *client)
> +{
> + struct gpio_desc *enable;
My preference would be "enable_gpio" to ensure it's easily
identifiable further on.
> + struct regmap *regmap;
> + unsigned int val;
'val' is not a great name for a variable that is used for a specific
purpose. How about 'revision'?
> + int ret;
> +
> + enable = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH);
> + if (IS_ERR(enable)) {
> + dev_err(&client->dev, "Failed to get 'enable' GPIO\n");
> + return PTR_ERR(enable);
> + }
> +
> + regmap = devm_regmap_init_i2c(client, &rt4831_regmap_config);
> + if (IS_ERR(regmap)) {
> + dev_err(&client->dev, "Failed to initialize regmap\n");
> + return PTR_ERR(regmap);
> + }
> +
> + ret = regmap_read(regmap, RT4831_REG_REVISION, &val);
> + if (ret) {
> + dev_err(&client->dev, "Failed to get H/W revision\n");
> + return ret;
> + }
> +
> + if ((val & RT4831_VID_MASK) != RICHTEK_VID) {
What does VID stand for here?
The fact that I have to ask probably means it should be changed.
Variant ID perhaps? If so, call the define 'VARIANT_ID'.
> + dev_err(&client->dev, "VID not matched, val = 0x%02x\n", val);
Using variable names means nothing to the user.
"revision: 0x%02x" ?
> + return -ENODEV;
> + }
> +
> + /*
> + * Used to prevent the abnormal shutdown.
> + * If SCL/SDA both keep low for one second to reset HW.
> + */
> + ret = regmap_update_bits(regmap, RT4831_REG_I2CPROT, RT4831_I2CSAFETMR_MASK,
> + RT4831_I2CSAFETMR_MASK);
> + if (ret) {
> + dev_err(&client->dev, "Failed to enable I2C safety timer\n");
> + return ret;
> + }
> +
> + return devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO, rt4831_subdevs,
> + ARRAY_SIZE(rt4831_subdevs), NULL, 0, NULL);
> +}
> +
> +static int rt4831_remove(struct i2c_client *client)
> +{
> + struct regmap *regmap = dev_get_regmap(&client->dev, NULL);
> +
> + /* Disable WLED and DSV outputs */
> + return regmap_update_bits(regmap, RT4831_REG_ENABLE, RT4831_RESET_MASK, RT4831_RESET_MASK);
> +}
> +
> +static void rt4831_shutdown(struct i2c_client *client)
> +{
> + struct regmap *regmap = dev_get_regmap(&client->dev, NULL);
> +
> + /* Disable WLED and DSV outputs */
> + regmap_update_bits(regmap, RT4831_REG_ENABLE, RT4831_RESET_MASK, RT4831_RESET_MASK);
> +}
> +
> +static const struct of_device_id __maybe_unused rt4831_of_match[] = {
> + { .compatible = "richtek,rt4831", },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, rt4831_of_match);
> +
> +static struct i2c_driver rt4831_driver = {
> + .driver = {
> + .name = "rt4831",
> + .of_match_table = of_match_ptr(rt4831_of_match),
The trend is to not use of_match_ptr() anymore, as these devices can
not be instantiated using ACPI.
> + },
> + .probe_new = rt4831_probe,
> + .remove = rt4831_remove,
> + .shutdown = rt4831_shutdown,
> +};
> +module_i2c_driver(rt4831_driver);
> +
> +MODULE_AUTHOR("ChiYuan Huang <cy_huang@...htek.com>");
> +MODULE_LICENSE("GPL v2");
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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