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Subject[PATCH 4/4] mfd: ene-kb3930: Add driver for ENE KB3930 Embedded Controller
Date
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@v3.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 2b203290e7b9f..d34cf1a026c86 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 b83f172545e1e..ee9a5260a26cd 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 0000000000000..1123f3a1c816a
--- /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>
+
+enum {
+ EC_DATA_IN = 0x00,
+ EC_RAM_OUT = 0x80,
+ EC_RAM_IN = 0x81,
+};
+
+enum {
+ EC_MODEL_ID = 0x30,
+ EC_VERSION_MAJ = 0x31,
+ EC_VERSION_MIN = 0x32,
+};
+
+struct kb3930 {
+ struct i2c_client *client;
+ struct regmap *ec_ram;
+ struct gpio_descs *off_gpios;
+};
+
+struct kb3930 *global_kb3930;
+
+static void kb3930_off(struct kb3930 *priv, int poweroff)
+{
+ gpiod_direction_output(priv->off_gpios->desc[1], poweroff);
+
+ while (1) {
+ mdelay(50);
+ gpiod_direction_output(priv->off_gpios->desc[0], 0);
+ mdelay(50);
+ gpiod_direction_output(priv->off_gpios->desc[0], 1);
+ }
+}
+
+static int kb3930_restart(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ kb3930_off(global_kb3930, 0);
+ return NOTIFY_DONE;
+}
+
+static void kb3930_power_off(void)
+{
+ kb3930_off(global_kb3930, 1);
+}
+
+static struct notifier_block kb3930_restart_nb = {
+ .notifier_call = kb3930_restart,
+ .priority = 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,
+ .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;
+ unsigned int model_id;
+ int ret;
+
+ if (global_kb3930)
+ return -EEXIST;
+
+ 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,
+ 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 (of_property_read_bool (np, "system-power-controller")) {
+ priv->off_gpios = devm_gpiod_get_array_optional(dev, "off",
+ GPIOD_IN);
+ }
+ if (IS_ERR(priv->off_gpios))
+ return PTR_ERR(priv->off_gpios);
+ if (priv->off_gpios->ndescs < 2) {
+ dev_err(dev, "invalid off-gpios property\n");
+ return -EINVAL;
+ }
+ 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");
+ 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);
+
+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@v3.sk>");
+MODULE_DESCRIPTION("ENE KB3930 Embedded Controller Driver");
+MODULE_LICENSE("Dual BSD/GPL");
--
2.25.1
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