On Wed, 17 Jun 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@xxxxx>
>
> ---
> Changes since v3:
> - Clarify that the power-off function is provided by this driver while
> LEDS_ARIEL is necessary to drive the leds in Kconfig help text
> - s/kb3930_power_off/kb3930_pm_power_off/, s/global_kb3930/kb3930_power_off/
> - Don't fail with -EEXIST with more than one instance
> - s/ret < 0/ret/ for devm_mfd_add_devices() return value
> - Drop a \n between struct i2c_driver and module_i2c_driver()
>
> Changes since v2:
> - Sort the includes
> - s/EC_MODEL_ID/EC_MODEL/
> - Add a couple of clarifying comments
> - Use #defines for values used in poweroff routine
> - Remove priority from a restart notifier block
> - s/priv/ddata/
> - s/ec_ram/ram_regmap/ for the regmap name
> - Fix the error handling when getting off gpios was not successful
> - Remove a useless dev_info at the end of probe()
> - Use i2c probe_new() callback, drop i2c_device_id
> - Modify the logic in checking the model ID
Much better. Just a couple of nits to fix.
> drivers/mfd/Kconfig | 11 ++
> drivers/mfd/Makefile | 1 +
> drivers/mfd/ene-kb3930.c | 211 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 223 insertions(+)
> create mode 100644 drivers/mfd/ene-kb3930.c
>
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index a37d7d1713820..7569f1d1703e3 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -398,6 +398,17 @@ 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"
What is "ENE"?
> + depends on I2C
> + depends on MACH_MMP3_DT || COMPILE_TEST
> + select MFD_CORE
> + help
> + This adds support for the power-off functionality and access to
> + the registers that control LEDS and USB port power on ENE KB3930
> + Embedded Controller. To use the LED functionality LEDS_ARIEL must
> + be enabled.
> +
> 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 9367a92f795a6..11085a6968398 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_MFD_GATEWORKS_GSC) += gateworks-gsc.o
>
> diff --git a/drivers/mfd/ene-kb3930.c b/drivers/mfd/ene-kb3930.c
> new file mode 100644
> index 0000000000000..75eced148ce53
> --- /dev/null
> +++ b/drivers/mfd/ene-kb3930.c
> @@ -0,0 +1,211 @@
> +// SPDX-License-Identifier: BSD-2-Clause OR GPL-2.0-or-later
> +/*
> + * ENE KB3930 Embedded Controller Driver
> + *
> + * Copyright (C) 2020 Lubomir Rintel
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/mfd/core.h>
> +#include <linux/module.h>
> +#include <linux/reboot.h>
> +#include <linux/regmap.h>
> +
> +/* I2C registers that are multiplexing access to the EC RAM. */
> +enum {
> + EC_DATA_IN = 0x00,
> + EC_RAM_OUT = 0x80,
> + EC_RAM_IN = 0x81,
> +};
> +
> +/* EC RAM registers. */
> +enum {
> + EC_MODEL = 0x30,
> + EC_VERSION_MAJ = 0x31,
> + EC_VERSION_MIN = 0x32,
> +};
> +
> +struct kb3930 {
> + struct i2c_client *client;
> + struct regmap *ram_regmap;
> + struct gpio_descs *off_gpios;
> +};
> +
> +struct kb3930 *kb3930_power_off;
> +
> +#define EC_GPIO_WAVE 0
> +#define EC_GPIO_OFF_MODE 1
> +
> +#define EC_OFF_MODE_REBOOT 0
> +#define EC_OFF_MODE_POWER 1
> +
> +static void kb3930_off(struct kb3930 *ddata, int off_mode)
> +{
> + gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_OFF_MODE],
> + off_mode);
> +
> + /*
> + * The EC initiates a shutdown when it detects a 10 MHz wave, inspecting the
> + * other GPIO pin to decide whether it's supposed to turn the power off or
> + * reset the board.
> + */
> + while (1) {
> + mdelay(50);
> + gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 0);
> + mdelay(50);
> + gpiod_direction_output(ddata->off_gpios->desc[EC_GPIO_WAVE], 1);
> + }
The comment describes what the EC is expecting, but says nothing about
what these lines of code do, or why they're required.
> +}
> +
> +static int kb3930_restart(struct notifier_block *this,
> + unsigned long mode, void *cmd)
> +{
> + kb3930_off(kb3930_power_off, EC_OFF_MODE_REBOOT);
> + return NOTIFY_DONE;
> +}
> +
> +static void kb3930_pm_power_off(void)
> +{
> + kb3930_off(kb3930_power_off, EC_OFF_MODE_POWER);
> +}
> +
> +static struct notifier_block kb3930_restart_nb = {
> + .notifier_call = kb3930_restart,
> +};
> +
> +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 *ddata = context;
> +
> + return i2c_smbus_write_word_data(ddata->client, EC_RAM_OUT,
> + (val << 8) | reg);
> +}
> +
> +static int kb3930_ec_ram_reg_read(void *context, unsigned int reg,
> + unsigned int *val)
> +{
> + struct kb3930 *ddata = context;
> + int ret;
> +
> + ret = i2c_smbus_write_word_data(ddata->client, EC_RAM_IN, reg);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_smbus_read_word_data(ddata->client, EC_DATA_IN);
> + if (ret < 0)
> + return ret;
> +
> + *val = ret >> 8;
> + return 0;
> +}
> +
> +static const struct regmap_config kb3930_ram_regmap_config = {
> + .name = "ec_ram",
> + .reg_bits = 8,
> + .val_bits = 8,
> + .reg_stride = 1,
> + .max_register = 0xff,
> + .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)
> +{
> + struct device *dev = &client->dev;
> + struct device_node *np = dev->of_node;
> + struct kb3930 *ddata;
> + unsigned int model;
> + int ret;
> +
> + ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
> + if (!ddata)
> + return -ENOMEM;
> +
> + kb3930_power_off = ddata;
> + ddata->client = client;
> + i2c_set_clientdata(client, ddata);
> +
> + ddata->ram_regmap = devm_regmap_init(dev, NULL, ddata,
> + &kb3930_ram_regmap_config);
> + if (IS_ERR(ddata->ram_regmap))
> + return PTR_ERR(ddata->ram_regmap);
> +
> + ret = regmap_read(ddata->ram_regmap, EC_MODEL, &model);
> + if (ret < 0)
> + return ret;
> +
> + /* Currently we only support the cells present on Dell Ariel model. */
> + if (model != 'J') {
> + dev_err(dev, "unknown board model: %02x\n", model);
> + return -ENODEV;
> + }
> +
> + /* These are the cells valid for model == 'J' only. */
The previous comment makes this superfluous.
> + ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO,
> + ariel_ec_cells,
> + ARRAY_SIZE(ariel_ec_cells),
> + NULL, 0, NULL);
> + if (ret)
> + return ret;
> +
> + if (of_property_read_bool(np, "system-power-controller")) {
> + ddata->off_gpios =
> + devm_gpiod_get_array_optional(dev, "off", GPIOD_IN);
> + if (IS_ERR(ddata->off_gpios))
> + return PTR_ERR(ddata->off_gpios);
> + if (ddata->off_gpios->ndescs < 2) {
> + dev_err(dev, "invalid off-gpios property\n");
> + return -EINVAL;
> + }
> + }
'\n' here.
> + if (ddata->off_gpios) {
> + register_restart_handler(&kb3930_restart_nb);
> + if (pm_power_off == NULL)
if (!pm_power_off)
> + pm_power_off = kb3930_pm_power_off;
> + }
> +
> + return 0;
> +}
> +
> +static int kb3930_remove(struct i2c_client *client)
> +{
> + struct kb3930 *ddata = i2c_get_clientdata(client);
> +
> + if (ddata->off_gpios) {
> + if (pm_power_off == kb3930_pm_power_off)
> + pm_power_off = NULL;
> + unregister_restart_handler(&kb3930_restart_nb);
> + }
> + kb3930_power_off = NULL;
> +
> + return 0;
> +}
> +
> +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_new = kb3930_probe,
> + .remove = kb3930_remove,
> + .driver = {
> + .name = "ene-kb3930",
> + .of_match_table = of_match_ptr(kb3930_dt_ids),
> + },
> +};
> +module_i2c_driver(kb3930_driver);
> +
> +MODULE_AUTHOR("Lubomir Rintel <lkundrak@xxxxx>");
> +MODULE_DESCRIPTION("ENE KB3930 Embedded Controller Driver");
> +MODULE_LICENSE("Dual BSD/GPL");
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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