Re: [PATCH v9 4/9] mfd: add base driver for qnap-mcu devices

Kees Bakker
2024-12-19T19:20:16Z

Op 07-11-2024 om 12:47 schreef Heiko Stuebner:
> These microcontroller units are used in network-attached-storage devices
> made by QNAP and provide additional functionality to the system.
>
> This adds the base driver that implements the serial protocol via
> serdev and additionally hooks into the poweroff handlers to turn
> off the parts of the system not supplied by the general PMIC.
>
> Turning off (at least the TSx33 devices using Rockchip SoCs) consists of
> two separate actions. Turning off the MCU alone does not turn off the main
> SoC and turning off only the SoC/PMIC does not turn off the hard-drives.
> Also if the MCU is not turned off, the system also won't start again until
> it is unplugged from power.
>
> So on shutdown the MCU needs to be turned off separately before the
> main PMIC.
>
> The protocol spoken by the MCU is sadly not documented, but was
> obtained by listening to the chatter on the serial port, as thankfully
> the "hal_app" program from QNAPs firmware allows triggering all/most
> MCU actions from the command line.
>
> The implementation of how to talk to the serial device got some
> inspiration from the rave-sp servdev driver.
>
> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
> ---
> MAINTAINERS | 6 +
> drivers/mfd/Kconfig | 13 ++
> drivers/mfd/Makefile | 2 +
> drivers/mfd/qnap-mcu.c | 338 +++++++++++++++++++++++++++++++++++
> include/linux/mfd/qnap-mcu.h | 26 +++
> 5 files changed, 385 insertions(+)
> create mode 100644 drivers/mfd/qnap-mcu.c
> create mode 100644 include/linux/mfd/qnap-mcu.h
>
> [...]
> diff --git a/drivers/mfd/qnap-mcu.c b/drivers/mfd/qnap-mcu.c
> new file mode 100644
> index 000000000000..4be39d8b2905
> --- /dev/null
> +++ b/drivers/mfd/qnap-mcu.c
> [...]
> +int qnap_mcu_exec(struct qnap_mcu *mcu,
> + const u8 *cmd_data, size_t cmd_data_size,
> + u8 *reply_data, size_t reply_data_size)
> +{
> + unsigned char rx[QNAP_MCU_RX_BUFFER_SIZE];
> + size_t length = reply_data_size + QNAP_MCU_CHECKSUM_SIZE;
> + struct qnap_mcu_reply *reply = &mcu->reply;
> + int ret = 0;
> +
> + if (length > sizeof(rx)) {
> + dev_err(&mcu->serdev->dev, "expected data too big for receive buffer");
> + return -EINVAL;
> + }
> +
> + mutex_lock(&mcu->bus_lock);
> +
> + reply->data = rx,
> + reply->length = length,
> + reply->received = 0,
> + reinit_completion(&reply->done);
> +
> + qnap_mcu_write(mcu, cmd_data, cmd_data_size);
> +
> + serdev_device_wait_until_sent(mcu->serdev, msecs_to_jiffies(QNAP_MCU_TIMEOUT_MS));
> +
> + if (!wait_for_completion_timeout(&reply->done, msecs_to_jiffies(QNAP_MCU_TIMEOUT_MS))) {
> + dev_err(&mcu->serdev->dev, "Command timeout\n");
> + ret = -ETIMEDOUT;
> + } else {
> + u8 crc = qnap_mcu_csum(rx, reply_data_size);
Here `rx` is still not initialized.
> +
> + if (crc != rx[reply_data_size]) {
> + dev_err(&mcu->serdev->dev,
> + "Invalid Checksum received\n");
> + ret = -EIO;
> + } else {
> + memcpy(reply_data, rx, reply_data_size);
> + }
> + }
> +
> + mutex_unlock(&mcu->bus_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(qnap_mcu_exec);