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Message-ID: <20200429060037.GT3559@dell>
Date: Wed, 29 Apr 2020 07:00:37 +0100
From: Lee Jones <lee.jones@...aro.org>
To: Lubomir Rintel <lkundrak@...sk>
Cc: Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] mfd: ene-kb3930: Add driver for ENE KB3930
Embedded Controller
On Sat, 25 Apr 2020, Lubomir Rintel wrote:
> This driver provides access to the EC RAM of said embedded controller
> attached to the I2C bus as well as optionally supporting its slightly weird
> power-off/restart protocol.
>
> A particular implementation of the EC firmware can be identified by a
> model byte. If this driver identifies the Dell Ariel platform, it
> registers the appropriate cells.
>
> Signed-off-by: Lubomir Rintel <lkundrak@...sk>
> ---
> drivers/mfd/Kconfig | 10 ++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/ene-kb3930.c | 209 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 220 insertions(+)
> create mode 100644 drivers/mfd/ene-kb3930.c
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 0a59249198d3..dae18a2beab5 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -398,6 +398,16 @@ config MFD_DLN2
> etc. must be enabled in order to use the functionality of
> the device.
>
> +config MFD_ENE_KB3930
> + tristate "ENE KB3930 Embedded Controller support"
> + depends on I2C
> + depends on MACH_MMP3_DT || COMPILE_TEST
> + select MFD_CORE
> + help
> + This adds support for accessing the registers on ENE KB3930, Embedded
> + Controller. Additional drivers such as LEDS_ARIEL must be enabled in
> + order to use the functionality of the device.
> +
> config MFD_EXYNOS_LPASS
> tristate "Samsung Exynos SoC Low Power Audio Subsystem"
> depends on ARCH_EXYNOS || COMPILE_TEST
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index f935d10cbf0f..2d2f5bc12841 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_ARCH_BCM2835) += bcm2835-pm.o
> obj-$(CONFIG_MFD_BCM590XX) += bcm590xx.o
> obj-$(CONFIG_MFD_BD9571MWV) += bd9571mwv.o
> obj-$(CONFIG_MFD_CROS_EC_DEV) += cros_ec_dev.o
> +obj-$(CONFIG_MFD_ENE_KB3930) += ene-kb3930.o
> obj-$(CONFIG_MFD_EXYNOS_LPASS) += exynos-lpass.o
>
> obj-$(CONFIG_HTC_PASIC3) += htc-pasic3.o
> diff --git a/drivers/mfd/ene-kb3930.c b/drivers/mfd/ene-kb3930.c
> new file mode 100644
> index 000000000000..1123f3a1c816
> --- /dev/null
> +++ b/drivers/mfd/ene-kb3930.c
> @@ -0,0 +1,209 @@
> +// SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later
> +/*
> + * ENE KB3930 Embedded Controller Driver
> + *
> + * Copyright (C) 2020 Lubomir Rintel
> + */
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/delay.h>
> +#include <linux/reboot.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/core.h>
Alphabetical.
> +enum {
> + EC_DATA_IN = 0x00,
> + EC_RAM_OUT = 0x80,
> + EC_RAM_IN = 0x81,
> +};
Are these registers?
> +enum {
> + EC_MODEL_ID = 0x30,
> + EC_VERSION_MAJ = 0x31,
> + EC_VERSION_MIN = 0x32,
> +};
As above?
> +struct kb3930 {
> + struct i2c_client *client;
> + struct regmap *ec_ram;
This is usually called 'regmap'.
> + struct gpio_descs *off_gpios;
> +};
> +
> +struct kb3930 *global_kb3930;
Globals are massively frowned upon. Please move it.
> +static void kb3930_off(struct kb3930 *priv, int poweroff)
> +{
> + gpiod_direction_output(priv->off_gpios->desc[1], poweroff);
> +
> + while (1) {
> + mdelay(50);
Why 50?
> + gpiod_direction_output(priv->off_gpios->desc[0], 0);
> + mdelay(50);
> + gpiod_direction_output(priv->off_gpios->desc[0], 1);
> + }
> +}
Please define all of the magic numbers in this function.
> +static int kb3930_restart(struct notifier_block *this,
> + unsigned long mode, void *cmd)
> +{
Put 'struct kb3930_restart_nb' into 'struct kb3930' then use
container_of to obtain a pointer to 'struct kb3930_restart_nb'.
See drivers/power/reset/gpio-restart.c for an example.
> + kb3930_off(global_kb3930, 0);
Define the 0 please.
> + return NOTIFY_DONE;
> +}
> +
> +static void kb3930_power_off(void)
> +{
> + kb3930_off(global_kb3930, 1);
Define the 1 please.
> +}
> +
> +static struct notifier_block kb3930_restart_nb = {
> + .notifier_call = kb3930_restart,
> + .priority = 128,
Why 128?
> +};
> +
> +static const struct mfd_cell ariel_ec_cells[] = {
> + { .name = "dell-wyse-ariel-led", },
> + { .name = "dell-wyse-ariel-power", },
> +};
> +
> +static int kb3930_ec_ram_reg_write(void *context, unsigned int reg,
> + unsigned int val)
> +{
> + struct kb3930 *priv = context;
> +
> + return i2c_smbus_write_word_data(priv->client, EC_RAM_OUT,
> + (val << 8) | reg);
> +}
> +
> +static int kb3930_ec_ram_reg_read(void *context, unsigned int reg,
> + unsigned int *val)
> +{
> + struct kb3930 *priv = context;
> + int ret;
> +
> + ret = i2c_smbus_write_word_data(priv->client, EC_RAM_IN, reg);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_smbus_read_word_data(priv->client, EC_DATA_IN);
> + if (ret < 0)
> + return ret;
> +
> + *val = ret >> 8;
> + return 0;
> +}
> +
> +static const struct regmap_config kb3930_ec_ram_regmap_config = {
> + .name = "ec_ram",
> + .reg_bits = 8,
> + .val_bits = 8,
> + .reg_stride = 1,
> + .max_register = 0xff,
Where are the list of register defines/enums?
> + .reg_write = kb3930_ec_ram_reg_write,
> + .reg_read = kb3930_ec_ram_reg_read,
> + .fast_io = false,
> +};
> +
> +static int kb3930_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct device *dev = &client->dev;
> + struct device_node *np = dev->of_node;
> + struct kb3930 *priv;
Not keen on 'info' or 'priv' for these.
Prefer it if you call this ddata (device/driver data).
> + unsigned int model_id;
Just 'model' is fine.
> + int ret;
> +
> + if (global_kb3930)
> + return -EEXIST;
Please no!
> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + global_kb3930 = priv;
> + priv->client = client;
> + i2c_set_clientdata(client, priv);
> +
> + priv->ec_ram = devm_regmap_init(dev, NULL, priv,
> + &kb3930_ec_ram_regmap_config);
> + if (IS_ERR(priv->ec_ram))
> + return PTR_ERR(priv->ec_ram);
> +
> + ret = regmap_read(priv->ec_ram, EC_MODEL_ID, &model_id);
> + if (ret < 0)
> + return ret;
> +
> + if (model_id == 'J') {
> + ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
Why NONE over AUTO?
> + ariel_ec_cells,
> + ARRAY_SIZE(ariel_ec_cells),
> + NULL, 0, NULL);
> + if (ret < 0)
> + return ret;
> + } else {
> + dev_err(dev, "unknown board model: %02x\n", model_id);
> + return -ENODEV;
If you reverse the logic here, you can put this in the if() and omit
the else.
> + }
> +
> + if (of_property_read_bool (np, "system-power-controller")) {
Remove the space before the '('.
> + priv->off_gpios = devm_gpiod_get_array_optional(dev, "off",
> + GPIOD_IN);
Please try to split the line just after the '='.
> + }
> + if (IS_ERR(priv->off_gpios))
> + return PTR_ERR(priv->off_gpios);
Shouldn't this be in the if() above?
> + if (priv->off_gpios->ndescs < 2) {
> + dev_err(dev, "invalid off-gpios property\n");
> + return -EINVAL;
> + }
This doesn't seem right. I thought they were optional?
> + if (priv->off_gpios) {
> + register_restart_handler(&kb3930_restart_nb);
> + if (pm_power_off == NULL)
> + pm_power_off = kb3930_power_off;
> + }
> +
> + dev_info(dev, "ENE KB3930 Embedded Controller\n");
Remove this line please.
> + return 0;
> +}
> +
> +static int kb3930_remove(struct i2c_client *client)
> +{
> + struct kb3930 *priv = i2c_get_clientdata(client);
> +
> + if (priv->off_gpios) {
> + if (pm_power_off == kb3930_power_off)
> + pm_power_off = NULL;
> + unregister_restart_handler(&kb3930_restart_nb);
> + }
> + global_kb3930 = NULL;
> +
> + return 0;
> +}
> +
> +static const struct i2c_device_id kb3930_ids[] = {
> + { "kb3930", 0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, kb3930_ids);
You can use .probe_new and omit this table.
> +static const struct of_device_id kb3930_dt_ids[] = {
> + { .compatible = "ene,kb3930" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, kb3930_dt_ids);
> +
> +static struct i2c_driver kb3930_driver = {
> + .probe = kb3930_probe,
> + .remove = kb3930_remove,
> + .driver = {
> + .name = "ene-kb3930",
> + .of_match_table = of_match_ptr(kb3930_dt_ids),
> + },
> + .id_table = kb3930_ids,
> +};
> +
> +module_i2c_driver(kb3930_driver);
> +
> +MODULE_AUTHOR("Lubomir Rintel <lkundrak@...sk>");
> +MODULE_DESCRIPTION("ENE KB3930 Embedded Controller Driver");
> +MODULE_LICENSE("Dual BSD/GPL");
--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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