--- /dev/null
+// 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/device.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/kstrtox.h>
+#include <linux/reboot.h>
+#include <linux/rtc.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+
+#include <linux/turris-omnia-mcu-interface.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, OMNIA_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, OMNIA_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, OMNIA_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 = OMNIA_CMD_POWER_OFF_POWERON_BUTTON;
+ else
+ arg = 0;
+
+ cmd[0] = OMNIA_CMD_POWER_OFF;
+ put_unaligned_le16(OMNIA_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(~0, (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] = OMNIA_CMD_GENERAL_CONTROL;
+
+ if (reboot_mode == REBOOT_HARD)
+ cmd[1] = cmd[2] = OMNIA_CTL_HARD_RST;
+ else
+ cmd[1] = cmd[2] = OMNIA_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 = dev_get_drvdata(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 = dev_get_drvdata(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 = dev_get_drvdata(dev);
+
+ if (mcu->features & OMNIA_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 & OMNIA_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;
+}
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