mfd: Add base driver for Netronix embedded controller
The Netronix embedded controller is a microcontroller found in some
e-book readers designed by the original design manufacturer Netronix,
Inc. It contains RTC, battery monitoring, system power management, and
PWM functionality.
This driver implements register access and version detection.
Third-party hardware documentation is available at:
https://github.com/neuschaefer/linux/wiki/Netronix-MSP430-embedded-controller
The EC supports interrupts, but the driver doesn't make use of them so
far.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b74efa4..a03de3f7 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -967,6 +967,17 @@
You need to select the mfd cell drivers separately.
The drivers do not support all features the board exposes.
+config MFD_NTXEC
+ tristate "Netronix embedded controller (EC)"
+ depends on OF || COMPILE_TEST
+ depends on I2C
+ select REGMAP_I2C
+ select MFD_CORE
+ help
+ Say yes here if you want to support the embedded controller found in
+ certain e-book readers designed by the original design manufacturer
+ Netronix.
+
config MFD_RETU
tristate "Nokia Retu and Tahvo multi-function device"
select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 834f546..bb5e8f2 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -218,6 +218,7 @@
obj-$(CONFIG_MFD_INTEL_PMT) += intel_pmt.o
obj-$(CONFIG_MFD_PALMAS) += palmas.o
obj-$(CONFIG_MFD_VIPERBOARD) += viperboard.o
+obj-$(CONFIG_MFD_NTXEC) += ntxec.o
obj-$(CONFIG_MFD_RC5T583) += rc5t583.o rc5t583-irq.o
obj-$(CONFIG_MFD_RK808) += rk808.o
obj-$(CONFIG_MFD_RN5T618) += rn5t618.o
diff --git a/drivers/mfd/ntxec.c b/drivers/mfd/ntxec.c
new file mode 100644
index 0000000..957de2b
--- /dev/null
+++ b/drivers/mfd/ntxec.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The Netronix embedded controller is a microcontroller found in some
+ * e-book readers designed by the original design manufacturer Netronix, Inc.
+ * It contains RTC, battery monitoring, system power management, and PWM
+ * functionality.
+ *
+ * This driver implements register access, version detection, and system
+ * power-off/reset.
+ *
+ * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net>
+ */
+
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/ntxec.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+#include <asm/unaligned.h>
+
+#define NTXEC_REG_VERSION 0x00
+#define NTXEC_REG_POWEROFF 0x50
+#define NTXEC_REG_POWERKEEP 0x70
+#define NTXEC_REG_RESET 0x90
+
+#define NTXEC_POWEROFF_VALUE 0x0100
+#define NTXEC_POWERKEEP_VALUE 0x0800
+#define NTXEC_RESET_VALUE 0xff00
+
+static struct i2c_client *poweroff_restart_client;
+
+static void ntxec_poweroff(void)
+{
+ int res;
+ u8 buf[3] = { NTXEC_REG_POWEROFF };
+ struct i2c_msg msgs[] = {
+ {
+ .addr = poweroff_restart_client->addr,
+ .flags = 0,
+ .len = sizeof(buf),
+ .buf = buf,
+ },
+ };
+
+ put_unaligned_be16(NTXEC_POWEROFF_VALUE, buf + 1);
+
+ res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (res < 0)
+ dev_warn(&poweroff_restart_client->dev,
+ "Failed to power off (err = %d)\n", res);
+
+ /*
+ * The time from the register write until the host CPU is powered off
+ * has been observed to be about 2.5 to 3 seconds. Sleep long enough to
+ * safely avoid returning from the poweroff handler.
+ */
+ msleep(5000);
+}
+
+static int ntxec_restart(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ int res;
+ u8 buf[3] = { NTXEC_REG_RESET };
+ /*
+ * NOTE: The lower half of the reset value is not sent, because sending
+ * it causes an I2C error. (The reset handler in the downstream driver
+ * does send the full two-byte value, but doesn't check the result).
+ */
+ struct i2c_msg msgs[] = {
+ {
+ .addr = poweroff_restart_client->addr,
+ .flags = 0,
+ .len = sizeof(buf) - 1,
+ .buf = buf,
+ },
+ };
+
+ put_unaligned_be16(NTXEC_RESET_VALUE, buf + 1);
+
+ res = i2c_transfer(poweroff_restart_client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (res < 0)
+ dev_warn(&poweroff_restart_client->dev,
+ "Failed to restart (err = %d)\n", res);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block ntxec_restart_handler = {
+ .notifier_call = ntxec_restart,
+ .priority = 128,
+};
+
+static const struct regmap_config regmap_config = {
+ .name = "ntxec",
+ .reg_bits = 8,
+ .val_bits = 16,
+ .cache_type = REGCACHE_NONE,
+ .val_format_endian = REGMAP_ENDIAN_BIG,
+};
+
+static const struct mfd_cell ntxec_subdevices[] = {
+ { .name = "ntxec-rtc" },
+ { .name = "ntxec-pwm" },
+};
+
+static int ntxec_probe(struct i2c_client *client)
+{
+ struct ntxec *ec;
+ unsigned int version;
+ int res;
+
+ ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
+ if (!ec)
+ return -ENOMEM;
+
+ ec->dev = &client->dev;
+
+ ec->regmap = devm_regmap_init_i2c(client, ®map_config);
+ if (IS_ERR(ec->regmap)) {
+ dev_err(ec->dev, "Failed to set up regmap for device\n");
+ return PTR_ERR(ec->regmap);
+ }
+
+ /* Determine the firmware version */
+ res = regmap_read(ec->regmap, NTXEC_REG_VERSION, &version);
+ if (res < 0) {
+ dev_err(ec->dev, "Failed to read firmware version number\n");
+ return res;
+ }
+
+ /* Bail out if we encounter an unknown firmware version */
+ switch (version) {
+ case NTXEC_VERSION_KOBO_AURA:
+ break;
+ default:
+ dev_err(ec->dev,
+ "Netronix embedded controller version %04x is not supported.\n",
+ version);
+ return -ENODEV;
+ }
+
+ dev_info(ec->dev,
+ "Netronix embedded controller version %04x detected.\n", version);
+
+ if (of_device_is_system_power_controller(ec->dev->of_node)) {
+ /*
+ * Set the 'powerkeep' bit. This is necessary on some boards
+ * in order to keep the system running.
+ */
+ res = regmap_write(ec->regmap, NTXEC_REG_POWERKEEP,
+ NTXEC_POWERKEEP_VALUE);
+ if (res < 0)
+ return res;
+
+ if (poweroff_restart_client)
+ /*
+ * Another instance of the driver already took
+ * poweroff/restart duties.
+ */
+ dev_err(ec->dev, "poweroff_restart_client already assigned\n");
+ else
+ poweroff_restart_client = client;
+
+ if (pm_power_off)
+ /* Another driver already registered a poweroff handler. */
+ dev_err(ec->dev, "pm_power_off already assigned\n");
+ else
+ pm_power_off = ntxec_poweroff;
+
+ res = register_restart_handler(&ntxec_restart_handler);
+ if (res)
+ dev_err(ec->dev,
+ "Failed to register restart handler: %d\n", res);
+ }
+
+ i2c_set_clientdata(client, ec);
+
+ res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, ntxec_subdevices,
+ ARRAY_SIZE(ntxec_subdevices), NULL, 0, NULL);
+ if (res)
+ dev_err(ec->dev, "Failed to add subdevices: %d\n", res);
+
+ return res;
+}
+
+static int ntxec_remove(struct i2c_client *client)
+{
+ if (client == poweroff_restart_client) {
+ poweroff_restart_client = NULL;
+ pm_power_off = NULL;
+ unregister_restart_handler(&ntxec_restart_handler);
+ }
+
+ return 0;
+}
+
+static const struct of_device_id of_ntxec_match_table[] = {
+ { .compatible = "netronix,ntxec", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, of_ntxec_match_table);
+
+static struct i2c_driver ntxec_driver = {
+ .driver = {
+ .name = "ntxec",
+ .of_match_table = of_ntxec_match_table,
+ },
+ .probe_new = ntxec_probe,
+ .remove = ntxec_remove,
+};
+module_i2c_driver(ntxec_driver);
+
+MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");
+MODULE_DESCRIPTION("Core driver for Netronix EC");
+MODULE_LICENSE("GPL");
