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.
Known problems:
- The reboot handler is installed in such a way that it directly calls
into the i2c subsystem to send the reboot command to the EC. This
means that the reboot handler may sleep, which is not allowed.
Signed-off-by: Jonathan Neuschäfer <j.neuschae...@gmx.net>
---
drivers/mfd/Kconfig | 7 ++
drivers/mfd/Makefile | 1 +
drivers/mfd/ntxec.c | 188 ++++++++++++++++++++++++++++++++++++++
include/linux/mfd/ntxec.h | 30 ++++++
4 files changed, 226 insertions(+)
create mode 100644 drivers/mfd/ntxec.c
create mode 100644 include/linux/mfd/ntxec.h
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index a37d7d1713820..78410b928648e 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -978,6 +978,13 @@ config MFD_VIPERBOARD
You need to select the mfd cell drivers separately.
The drivers do not support all features the board exposes.
+config MFD_NTXEC
+ bool "Netronix Embedded Controller"
+ depends on I2C && OF
+ help
+ Say yes here if you want to support the embedded controller of
+ certain e-book readers designed by the ODM 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 9367a92f795a6..19d9391ed6f32 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -218,6 +218,7 @@ obj-$(CONFIG_MFD_INTEL_MSIC) += intel_msic.o
obj-$(CONFIG_MFD_INTEL_PMC_BXT) += intel_pmc_bxt.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 0000000000000..82adea34ea746
--- /dev/null
+++ b/drivers/mfd/ntxec.c
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright 2020 Jonathan Neuschäfer
+//
+// MFD driver for the usually MSP430-based embedded controller used in certain
+// Netronix ebook reader board designs
+
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/mfd/ntxec.h>
+#include <linux/of_platform.h>
+#include <linux/pm.h>
+#include <linux/reboot.h>
+#include <linux/types.h>
+
+
+#define NTXEC_VERSION 0x00
+#define NTXEC_POWEROFF 0x50
+#define NTXEC_POWERKEEP 0x70
+#define NTXEC_RESET 0x90
+
+
+/* Register access */
+
+int ntxec_read16(struct ntxec *ec, u8 addr)
+{
+ u8 request[1] = { addr };
+ u8 response[2];
+ int res;
+
+ struct i2c_msg msgs[] = {
+ {
+ .addr = ec->client->addr,
+ .flags = ec->client->flags,
+ .len = sizeof(request),
+ .buf = request
+ }, {
+ .addr = ec->client->addr,
+ .flags = ec->client->flags | I2C_M_RD,
+ .len = sizeof(response),
+ .buf = response
+ }
+ };
+
+ res = i2c_transfer(ec->client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (res < 0)
+ return res;
+ if (res != ARRAY_SIZE(msgs))
+ return -EIO;
+
+ return get_unaligned_be16(response);
+}
+EXPORT_SYMBOL(ntxec_read16);
+
+int ntxec_write16(struct ntxec *ec, u8 addr, u16 value)
+{
+ u8 request[3] = { addr, };
+ int res;
+
+ put_unaligned_be16(value, request + 1);
+
+ res = i2c_transfer_buffer_flags(ec->client, request, sizeof(request),
+ ec->client->flags);
+ if (res < 0)
+ return res;
+
+ return 0;
+}
+EXPORT_SYMBOL(ntxec_write16);
+
+int ntxec_read8(struct ntxec *ec, u8 addr)
+{
+ int res = ntxec_read16(ec, addr);
+
+ if (res < 0)
+ return res;
+
+ return (res >> 8) & 0xff;
+}
+EXPORT_SYMBOL(ntxec_read8);
+
+int ntxec_write8(struct ntxec *ec, u8 addr, u8 value)
+{
+ return ntxec_write16(ec, addr, value << 8);
+}
+EXPORT_SYMBOL(ntxec_write8);
+
+
+/* Reboot/poweroff handling */
+
+static struct ntxec *poweroff_restart_instance;
+
+static void ntxec_poweroff(void)
+{
+ ntxec_write8(poweroff_restart_instance, NTXEC_POWEROFF, 0x01);
+ msleep(5000);
+}
+
+static int ntxec_restart(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ /* FIXME: The I2C driver sleeps, but restart handlers may not sleep */
+ ntxec_write8(poweroff_restart_instance, NTXEC_RESET, 0xff);
+ /* TODO: delay? */
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block ntxec_restart_handler = {
+ .notifier_call = ntxec_restart,
+ .priority = 128
+};
+
+
+/* Driver setup */
+
+static int ntxec_probe(struct i2c_client *client,
+ const struct i2c_device_id *ids)
+{
+ struct ntxec *ec;
+ int res;
+
+ ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
+ if (!ec)
+ return -ENOMEM;
+
+ ec->dev = &client->dev;
+ ec->client = client;
+
+ /* Determine the firmware version */
+ res = ntxec_read16(ec, NTXEC_VERSION);
+ if (res < 0) {
+ dev_dbg(ec->dev, "Failed to read firmware version number\n");
+ return res;
+ }
+ ec->version = res;
+
+ dev_info(ec->dev,
+ "Netronix embedded controller version %04x detected.\n",
+ ec->version);
+
+ /* For now, we don't support the new register layout. */
+ if (ntxec_has_new_layout(ec))
+ return -EOPNOTSUPP;
+
+ 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 = ntxec_write8(ec, NTXEC_POWERKEEP, 0x08);
+ if (res < 0)
+ return res;
+
+ /* Install poweroff handler */
+ WARN_ON(poweroff_restart_instance);
+ poweroff_restart_instance = ec;
+ if (pm_power_off != NULL)
+ /* TODO: Refactor among all poweroff drivers */
+ dev_err(ec->dev, "pm_power_off already assigned\n");
+ else
+ pm_power_off = ntxec_poweroff;
+
+ /* Install board reset handler */
+ res = register_restart_handler(&ntxec_restart_handler);
+ if (res < 0)
+ dev_err(ec->dev,
+ "Failed to register restart handler: %d\n",
res);
+ }
+
+ i2c_set_clientdata(client, ec);
+
+ return devm_of_platform_populate(ec->dev);
+}
+
+static const struct of_device_id of_ntxec_match_table[] = {
+ { .compatible = "netronix,ntxec", },
+ {}
+};
+
+static struct i2c_driver ntxec_driver = {
+ .driver = {
+ .name = "ntxec",
+ .of_match_table = of_ntxec_match_table,
+ },
+ .probe = ntxec_probe,
+};
+builtin_i2c_driver(ntxec_driver);
diff --git a/include/linux/mfd/ntxec.h b/include/linux/mfd/ntxec.h
new file mode 100644
index 0000000000000..9f9d6f2141751
--- /dev/null
+++ b/include/linux/mfd/ntxec.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2020 Jonathan Neuschäfer
+ *
+ * MFD access functions for the Netronix embedded controller.
+ */
+
+#ifndef NTXEC_H
+#define NTXEC_H
+
+#include <linux/types.h>
+
+struct ntxec {
+ struct device *dev;
+ struct i2c_client *client;
+ u16 version;
+ /* TODO: Add a mutex to protect actions consisting of multiple
accesses? */
+};
+
+static inline bool ntxec_has_new_layout(struct ntxec *ec)
+{
+ return ec->version == 0xe916;
+}
+
+int ntxec_read16(struct ntxec *ec, u8 addr);
+int ntxec_write16(struct ntxec *ec, u8 addr, u16 value);
+int ntxec_read8(struct ntxec *ec, u8 addr);
+int ntxec_write8(struct ntxec *ec, u8 addr, u8 value);
+
+#endif
--
2.27.0
