[PATCH v5 04/11] platform: cznic: turris-omnia-mcu: Add support for poweroff and wakeup

Marek Behún
2024-03-23T16:44:16Z

Add support for true board poweroff (MCU can disable all unnecessary
voltage regulators) and wakeup at a specified time, implemented via a
RTC driver so that the rtcwake utility can be used to configure it.

Signed-off-by: Marek Behún <kabel@kernel.org>
---
Changes since v4:
- the driver now registers the RTC with feature bit
RTC_FEATURE_ALARM_WAKEUP_ONLY, as requested by Alexandre Belloni
(see commit e99653afeb95 for explanation)
---
.../sysfs-bus-i2c-devices-turris-omnia-mcu | 16 ++
drivers/platform/cznic/Kconfig | 4 +
drivers/platform/cznic/Makefile | 1 +
.../platform/cznic/turris-omnia-mcu-base.c | 5 +
.../cznic/turris-omnia-mcu-sys-off-wakeup.c | 258 ++++++++++++++++++
drivers/platform/cznic/turris-omnia-mcu.h | 20 ++
6 files changed, 304 insertions(+)
create mode 100644 drivers/platform/cznic/turris-omnia-mcu-sys-off-wakeup.c

diff --git a/Documentation/ABI/testing/sysfs-bus-i2c-devices-turris-omnia-mcu b/Documentation/ABI/testing/sysfs-bus-i2c-devices-turris-omnia-mcu
index b27b60d00c87..564119849388 100644
--- a/Documentation/ABI/testing/sysfs-bus-i2c-devices-turris-omnia-mcu
+++ b/Documentation/ABI/testing/sysfs-bus-i2c-devices-turris-omnia-mcu
@@ -38,6 +38,22 @@ Description: (RW) The front button on the Turris Omnia router can be

Format: %s.

+What: /sys/bus/i2c/devices/<mcu_device>/front_button_poweron
+Date: July 2024
+KernelVersion: 6.10
+Contact: Marek Behún <kabel@kernel.org>
+Description: (RW) Newer versions of the microcontroller firmware of the
+ Turris Omnia router support powering off the router into true
+ low power mode. The router can be powered on by pressing the
+ front button.
+
+ This file configures whether front button power on is enabled.
+
+ This file is present only if the power off feature is supported
+ by the firmware.
+
+ Format: %i.
+
What: /sys/bus/i2c/devices/<mcu_device>/fw_features
Date: July 2024
KernelVersion: 6.10
diff --git a/drivers/platform/cznic/Kconfig b/drivers/platform/cznic/Kconfig
index 3a8c3edcd7e6..0a752aa654fa 100644
--- a/drivers/platform/cznic/Kconfig
+++ b/drivers/platform/cznic/Kconfig
@@ -19,10 +19,14 @@ config TURRIS_OMNIA_MCU
depends on I2C
select GPIOLIB
select GPIOLIB_IRQCHIP
+ select RTC_CLASS
help
Say Y here to add support for the features implemented by the
microcontroller on the CZ.NIC's Turris Omnia SOHO router.
The features include:
+ - board poweroff into true low power mode (with voltage regulators
+ disabled) and the ability to configure wake up from this mode (via
+ rtcwake)
- GPIO pins
- to get front button press events (the front button can be
configured either to generate press events to the CPU or to change
diff --git a/drivers/platform/cznic/Makefile b/drivers/platform/cznic/Makefile
index a6177f5b4fff..6f1470d1f673 100644
--- a/drivers/platform/cznic/Makefile
+++ b/drivers/platform/cznic/Makefile
@@ -3,3 +3,4 @@
obj-$(CONFIG_TURRIS_OMNIA_MCU) += turris-omnia-mcu.o
turris-omnia-mcu-objs := turris-omnia-mcu-base.o
turris-omnia-mcu-objs += turris-omnia-mcu-gpio.o
+turris-omnia-mcu-objs += turris-omnia-mcu-sys-off-wakeup.o
diff --git a/drivers/platform/cznic/turris-omnia-mcu-base.c b/drivers/platform/cznic/turris-omnia-mcu-base.c
index 4edaf7a53242..6ab4494335ca 100644
--- a/drivers/platform/cznic/turris-omnia-mcu-base.c
+++ b/drivers/platform/cznic/turris-omnia-mcu-base.c
@@ -161,6 +161,7 @@ static const struct attribute_group omnia_mcu_base_group = {
static const struct attribute_group *omnia_mcu_groups[] = {
&omnia_mcu_base_group,
&omnia_mcu_gpio_group,
+ &omnia_mcu_poweroff_group,
NULL
};

@@ -326,6 +327,10 @@ static int omnia_mcu_probe(struct i2c_client *client)
"Cannot read board info\n");
}

+ err = omnia_mcu_register_sys_off_and_wakeup(mcu);
+ if (err)
+ return err;
+
return omnia_mcu_register_gpiochip(mcu);
}

diff --git a/drivers/platform/cznic/turris-omnia-mcu-sys-off-wakeup.c b/drivers/platform/cznic/turris-omnia-mcu-sys-off-wakeup.c
new file mode 100644
index 000000000000..80144f288451
--- /dev/null
+++ b/drivers/platform/cznic/turris-omnia-mcu-sys-off-wakeup.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * CZ.NIC's Turris Omnia MCU system off and RTC wakeup driver
+ *
+ * This is not a true RTC driver (in the sense that it does not provide a
+ * real-time clock), rather the MCU implements a wakeup from powered off state
+ * at a specified time relative to MCU boot, and we expose this feature via RTC
+ * alarm, so that it can be used via the rtcwake command, which is the standard
+ * Linux command for this.
+ *
+ * 2024 by Marek Behún <kabel@kernel.org>
+ */
+
+#include <linux/crc32.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/reboot.h>
+#include <linux/rtc.h>
+#include <linux/sysfs.h>
+#include <linux/turris-omnia-mcu-interface.h>
+#include <linux/types.h>
+
+#include "turris-omnia-mcu.h"
+
+static int omnia_get_uptime_wakeup(const struct i2c_client *client, u32 *uptime,
+ u32 *wakeup)
+{
+ __le32 reply[2];
+ int err;
+
+ err = omnia_cmd_read(client, CMD_GET_UPTIME_AND_WAKEUP, reply,
+ sizeof(reply));
+ if (err)
+ return err;
+
+ if (uptime)
+ *uptime = le32_to_cpu(reply[0]);
+
+ if (wakeup)
+ *wakeup = le32_to_cpu(reply[1]);
+
+ return 0;
+}
+
+static int omnia_read_time(struct device *dev, struct rtc_time *tm)
+{
+ u32 uptime;
+ int err;
+
+ err = omnia_get_uptime_wakeup(to_i2c_client(dev), &uptime, NULL);
+ if (err)
+ return err;
+
+ rtc_time64_to_tm(uptime, tm);
+
+ return 0;
+}
+
+static int omnia_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct omnia_mcu *mcu = i2c_get_clientdata(client);
+ u32 wakeup;
+ int err;
+
+ err = omnia_get_uptime_wakeup(client, NULL, &wakeup);
+ if (err)
+ return err;
+
+ alrm->enabled = !!wakeup;
+ rtc_time64_to_tm(wakeup ?: mcu->rtc_alarm, &alrm->time);
+
+ return 0;
+}
+
+static int omnia_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct omnia_mcu *mcu = i2c_get_clientdata(client);
+
+ mcu->rtc_alarm = rtc_tm_to_time64(&alrm->time);
+
+ if (alrm->enabled)
+ return omnia_cmd_write_u32(client, CMD_SET_WAKEUP,
+ mcu->rtc_alarm);
+
+ return 0;
+}
+
+static int omnia_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct omnia_mcu *mcu = i2c_get_clientdata(client);
+
+ return omnia_cmd_write_u32(client, CMD_SET_WAKEUP,
+ enabled ? mcu->rtc_alarm : 0);
+}
+
+static const struct rtc_class_ops omnia_rtc_ops = {
+ .read_time = omnia_read_time,
+ .read_alarm = omnia_read_alarm,
+ .set_alarm = omnia_set_alarm,
+ .alarm_irq_enable = omnia_alarm_irq_enable,
+};
+
+static int omnia_power_off(struct sys_off_data *data)
+{
+ struct omnia_mcu *mcu = data->cb_data;
+ __be32 tmp;
+ u8 cmd[9];
+ u16 arg;
+ int err;
+
+ if (mcu->front_button_poweron)
+ arg = CMD_POWER_OFF_POWERON_BUTTON;
+ else
+ arg = 0;
+
+ cmd[0] = CMD_POWER_OFF;
+ put_unaligned_le16(CMD_POWER_OFF_MAGIC, &cmd[1]);
+ put_unaligned_le16(arg, &cmd[3]);
+
+ /*
+ * Although all values from and to MCU are passed in little-endian, the
+ * MCU's CRC unit uses big-endian CRC32 polynomial (0x04c11db7), so we
+ * need to use crc32_be() here.
+ */
+ tmp = cpu_to_be32(get_unaligned_le32(&cmd[1]));
+ put_unaligned_le32(crc32_be(0xffffffff, (void *)&tmp, sizeof(tmp)),
+ &cmd[5]);
+
+ err = omnia_cmd_write(mcu->client, cmd, sizeof(cmd));
+ if (err)
+ dev_err(&mcu->client->dev,
+ "Unable to send the poweroff command: %d\n", err);
+
+ return NOTIFY_DONE;
+}
+
+static int omnia_restart(struct sys_off_data *data)
+{
+ struct omnia_mcu *mcu = data->cb_data;
+ u8 cmd[3];
+ int err;
+
+ cmd[0] = CMD_GENERAL_CONTROL;
+
+ if (reboot_mode == REBOOT_HARD)
+ cmd[1] = cmd[2] = CTL_HARD_RST;
+ else
+ cmd[1] = cmd[2] = CTL_LIGHT_RST;
+
+ err = omnia_cmd_write(mcu->client, cmd, sizeof(cmd));
+ if (err)
+ dev_err(&mcu->client->dev,
+ "Unable to send the restart command: %d\n", err);
+
+ /*
+ * MCU needs a little bit to process the I2C command, otherwise it will
+ * do a light reset based on SOC SYSRES_OUT pin.
+ */
+ mdelay(1);
+
+ return NOTIFY_DONE;
+}
+
+static ssize_t front_button_poweron_show(struct device *dev,
+ struct device_attribute *a, char *buf)
+{
+ struct omnia_mcu *mcu = i2c_get_clientdata(to_i2c_client(dev));
+
+ return sysfs_emit(buf, "%d\n", mcu->front_button_poweron);
+}
+
+static ssize_t front_button_poweron_store(struct device *dev,
+ struct device_attribute *a,
+ const char *buf, size_t count)
+{
+ struct omnia_mcu *mcu = i2c_get_clientdata(to_i2c_client(dev));
+ bool val;
+ int err;
+
+ err = kstrtobool(buf, &val);
+ if (err)
+ return err;
+
+ mcu->front_button_poweron = val;
+
+ return count;
+}
+static DEVICE_ATTR_RW(front_button_poweron);
+
+static struct attribute *omnia_mcu_poweroff_attrs[] = {
+ &dev_attr_front_button_poweron.attr,
+ NULL
+};
+
+static umode_t poweroff_attrs_visible(struct kobject *kobj, struct attribute *a,
+ int n)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct omnia_mcu *mcu = i2c_get_clientdata(to_i2c_client(dev));
+
+ if (mcu->features & FEAT_POWEROFF_WAKEUP)
+ return a->mode;
+
+ return 0;
+}
+
+const struct attribute_group omnia_mcu_poweroff_group = {
+ .attrs = omnia_mcu_poweroff_attrs,
+ .is_visible = poweroff_attrs_visible,
+};
+
+int omnia_mcu_register_sys_off_and_wakeup(struct omnia_mcu *mcu)
+{
+ struct device *dev = &mcu->client->dev;
+ int err;
+
+ /* MCU restart is always available */
+ err = devm_register_sys_off_handler(dev, SYS_OFF_MODE_RESTART,
+ SYS_OFF_PRIO_FIRMWARE,
+ omnia_restart, mcu);
+ if (err)
+ return dev_err_probe(dev, err,
+ "Cannot register system restart handler\n");
+
+ /*
+ * Poweroff and wakeup are available only if POWEROFF_WAKEUP feature is
+ * present.
+ */
+ if (!(mcu->features & FEAT_POWEROFF_WAKEUP))
+ return 0;
+
+ err = devm_register_sys_off_handler(dev, SYS_OFF_MODE_POWER_OFF,
+ SYS_OFF_PRIO_FIRMWARE,
+ omnia_power_off, mcu);
+ if (err)
+ return dev_err_probe(dev, err,
+ "Cannot register system power off handler\n");
+
+ mcu->rtcdev = devm_rtc_allocate_device(dev);
+ if (IS_ERR(mcu->rtcdev))
+ return dev_err_probe(dev, PTR_ERR(mcu->rtcdev),
+ "Cannot allocate RTC device\n");
+
+ mcu->rtcdev->ops = &omnia_rtc_ops;
+ mcu->rtcdev->range_max = U32_MAX;
+ set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, mcu->rtcdev->features);
+
+ err = devm_rtc_register_device(mcu->rtcdev);
+ if (err)
+ return dev_err_probe(dev, err, "Cannot register RTC device\n");
+
+ mcu->front_button_poweron = true;
+
+ return 0;
+}
diff --git a/drivers/platform/cznic/turris-omnia-mcu.h b/drivers/platform/cznic/turris-omnia-mcu.h
index 143c63001e8f..af9845d1c6d2 100644
--- a/drivers/platform/cznic/turris-omnia-mcu.h
+++ b/drivers/platform/cznic/turris-omnia-mcu.h
@@ -13,9 +13,11 @@
#include <linux/i2c.h>
#include <linux/if_ether.h>
#include <linux/mutex.h>
+#include <linux/rtc.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <asm/byteorder.h>
+#include <asm/unaligned.h>

struct omnia_mcu {
struct i2c_client *client;
@@ -35,6 +37,11 @@ struct omnia_mcu {
struct delayed_work button_release_emul_work;
u16 last_status;
bool button_pressed_emul;
+
+ /* RTC device for configuring wake-up */
+ struct rtc_device *rtcdev;
+ u32 rtc_alarm;
+ bool front_button_poweron;
};

static inline int omnia_cmd_write(const struct i2c_client *client, void *cmd,
@@ -47,6 +54,17 @@ static inline int omnia_cmd_write(const struct i2c_client *client, void *cmd,
return ret < 0 ? ret : 0;
}

+static inline int omnia_cmd_write_u32(const struct i2c_client *client, u8 cmd,
+ u32 val)
+{
+ u8 buf[5];
+
+ buf[0] = cmd;
+ put_unaligned_le32(val, &buf[1]);
+
+ return omnia_cmd_write(client, buf, sizeof(buf));
+}
+
static inline int omnia_cmd_read(const struct i2c_client *client, u8 cmd,
void *reply, unsigned int len)
{
@@ -126,7 +144,9 @@ static inline int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
}

extern const struct attribute_group omnia_mcu_gpio_group;
+extern const struct attribute_group omnia_mcu_poweroff_group;

int omnia_mcu_register_gpiochip(struct omnia_mcu *mcu);
+int omnia_mcu_register_sys_off_and_wakeup(struct omnia_mcu *mcu);

#endif /* __TURRIS_OMNIA_MCU_H */
--
2.43.2