Re: [PATCH v7 4/9] platform: cznic: turris-omnia-mcu: Add support for poweroff and wakeup

[Alexandre Belloni <alexandre.belloni@bootlin.com>]

On 24/04/2024 19:38:03+0200, Marek Behún wrote:
> 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>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
>  .../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 53fd8f1777a3..a185ef882e44 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-y		:= turris-omnia-mcu-base.o
>  turris-omnia-mcu-y		+= turris-omnia-mcu-gpio.o
> +turris-omnia-mcu-y		+= 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 708b084cb5da..697ace090bda 100644
> --- a/drivers/platform/cznic/turris-omnia-mcu-base.c
> +++ b/drivers/platform/cznic/turris-omnia-mcu-base.c
> @@ -195,6 +195,7 @@ 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
>  };
>  
> @@ -360,6 +361,10 @@ 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..fbd1b4cd7011
> --- /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 = 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 & 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 e8d9bf1c8fdc..6179a4f2069e 100644
> --- a/drivers/platform/cznic/turris-omnia-mcu.h
> +++ b/drivers/platform/cznic/turris-omnia-mcu.h
> @@ -12,9 +12,11 @@
>  #include <linux/gpio/driver.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;
> @@ -34,6 +36,11 @@ 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;
>  };
>  
>  int omnia_cmd_write_read(const struct i2c_client *client,
> @@ -46,6 +53,17 @@ static inline int omnia_cmd_write(const struct i2c_client *client, void *cmd,
>  	return omnia_cmd_write_read(client, cmd, len, NULL, 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)
>  {
> @@ -107,7 +125,9 @@ 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
> 
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com