Re: [PATCH v2 3/5] mfd: cros-ec: Introduce CEC commands and events definitions.

[Hans Verkuil]

On 05/15/2018 04:42 PM, Neil Armstrong wrote:
> The EC can expose a CEC bus, this patch adds the CEC related definitions
> needed by the cros-ec-cec driver.
> Having a 16 byte mkbp event size makes it possible to send CEC
> messages from the EC to the AP directly inside the mkbp event
> instead of first doing a notification and then a read.
> 
> Signed-off-by: Stefan Adolfsson <sadolfsson@xxxxxxxxxxxx>
> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> ---
>  drivers/platform/chrome/cros_ec_proto.c | 42 +++++++++++++----
>  include/linux/mfd/cros_ec.h             |  2 +-
>  include/linux/mfd/cros_ec_commands.h    | 80 +++++++++++++++++++++++++++++++++
>  3 files changed, 114 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> index e7bbdf9..ba47f79 100644
> --- a/drivers/platform/chrome/cros_ec_proto.c
> +++ b/drivers/platform/chrome/cros_ec_proto.c
> @@ -504,29 +504,53 @@ int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
>  }
>  EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
>  
> +static int get_next_event_xfer(struct cros_ec_device *ec_dev,
> +			       struct cros_ec_command *msg,
> +			       int version, uint32_t size)
> +{
> +	int ret;
> +
> +	msg->version = version;
> +	msg->command = EC_CMD_GET_NEXT_EVENT;
> +	msg->insize = size;
> +	msg->outsize = 0;
> +
> +	ret = cros_ec_cmd_xfer(ec_dev, msg);
> +	if (ret > 0) {
> +		ec_dev->event_size = ret - 1;
> +		memcpy(&ec_dev->event_data, msg->data, size);
> +	}
> +
> +	return ret;
> +}
> +
>  static int get_next_event(struct cros_ec_device *ec_dev)
>  {
>  	u8 buffer[sizeof(struct cros_ec_command) + sizeof(ec_dev->event_data)];
>  	struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
> +	static int cmd_version = 1;
>  	int ret;
>  
> +	BUILD_BUG_ON(sizeof(union ec_response_get_next_data_v1) != 16);

Use the define instead of hardcoding 16. I'm not really sure why you need this.
If cec_message uses the right define for the array size (see my comment below),
then this really can't go wrong, can it?

> +
>  	if (ec_dev->suspended) {
>  		dev_dbg(ec_dev->dev, "Device suspended.\n");
>  		return -EHOSTDOWN;
>  	}
>  
> -	msg->version = 0;
> -	msg->command = EC_CMD_GET_NEXT_EVENT;
> -	msg->insize = sizeof(ec_dev->event_data);
> -	msg->outsize = 0;
> +	if (cmd_version == 1) {
> +		ret = get_next_event_xfer(ec_dev, msg, cmd_version,
> +					  sizeof(ec_dev->event_data));
> +		if (ret != EC_RES_INVALID_VERSION)
> +			return ret;
>  
> -	ret = cros_ec_cmd_xfer(ec_dev, msg);
> -	if (ret > 0) {
> -		ec_dev->event_size = ret - 1;
> -		memcpy(&ec_dev->event_data, msg->data,
> -		       sizeof(ec_dev->event_data));
> +		/* Fallback to version 0 for future send attempts */
> +		cmd_version = 0;
>  	}
>  
> +	ret = get_next_event_xfer(ec_dev, msg, cmd_version,
> +				  sizeof(struct ec_response_get_next_event));
> +
>  	return ret;
>  }
>  
> diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
> index 2d4e23c..f3415eb 100644
> --- a/include/linux/mfd/cros_ec.h
> +++ b/include/linux/mfd/cros_ec.h
> @@ -147,7 +147,7 @@ struct cros_ec_device {
>  	bool mkbp_event_supported;
>  	struct blocking_notifier_head event_notifier;
>  
> -	struct ec_response_get_next_event event_data;
> +	struct ec_response_get_next_event_v1 event_data;
>  	int event_size;
>  	u32 host_event_wake_mask;
>  };
> diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
> index f2edd99..18df466 100644
> --- a/include/linux/mfd/cros_ec_commands.h
> +++ b/include/linux/mfd/cros_ec_commands.h
> @@ -804,6 +804,8 @@ enum ec_feature_code {
>  	EC_FEATURE_MOTION_SENSE_FIFO = 24,
>  	/* EC has RTC feature that can be controlled by host commands */
>  	EC_FEATURE_RTC = 27,
> +	/* EC supports CEC commands */
> +	EC_FEATURE_CEC = 35,
>  };
>  
>  #define EC_FEATURE_MASK_0(event_code) (1UL << (event_code % 32))
> @@ -2078,6 +2080,12 @@ enum ec_mkbp_event {
>  	/* EC sent a sysrq command */
>  	EC_MKBP_EVENT_SYSRQ = 6,
>  
> +	/* Notify the AP that something happened on CEC */
> +	EC_MKBP_CEC_EVENT = 8,
> +
> +	/* Send an incoming CEC message to the AP */
> +	EC_MKBP_EVENT_CEC_MESSAGE = 9,
> +
>  	/* Number of MKBP events */
>  	EC_MKBP_EVENT_COUNT,
>  };
> @@ -2093,12 +2101,31 @@ union ec_response_get_next_data {
>  	uint32_t   sysrq;
>  } __packed;
>  
> +union ec_response_get_next_data_v1 {
> +	uint8_t   key_matrix[16];
> +
> +	/* Unaligned */
> +	uint32_t  host_event;
> +
> +	uint32_t   buttons;
> +	uint32_t   switches;
> +	uint32_t   sysrq;
> +	uint32_t   cec_events;
> +	uint8_t    cec_message[16];
> +} __packed;
> +
>  struct ec_response_get_next_event {
>  	uint8_t event_type;
>  	/* Followed by event data if any */
>  	union ec_response_get_next_data data;
>  } __packed;
>  
> +struct ec_response_get_next_event_v1 {
> +	uint8_t event_type;
> +	/* Followed by event data if any */
> +	union ec_response_get_next_data_v1 data;
> +} __packed;
> +
>  /* Bit indices for buttons and switches.*/
>  /* Buttons */
>  #define EC_MKBP_POWER_BUTTON	0
> @@ -2828,6 +2855,59 @@ struct ec_params_reboot_ec {
>  /* Current version of ACPI memory address space */
>  #define EC_ACPI_MEM_VERSION_CURRENT 1
>  
> +/*****************************************************************************/
> +/*
> + * HDMI CEC commands
> + *
> + * These commands are for sending and receiving message via HDMI CEC
> + */
> +#define MAX_CEC_MSG_LEN 16

Hmm, uapi/linux/cec.h already defines CEC_MAX_MSG_SIZE with the same value.
Perhaps it is better to include linux/cec.h here instead of creating a second
define?

And shouldn't this define also be used for the cec_message array above?

Regards,

	Hans

> +
> +/* CEC message from the AP to be written on the CEC bus */
> +#define EC_CMD_CEC_WRITE_MSG 0x00B8
> +
> +/* Message to write to the CEC bus */
> +struct ec_params_cec_write {
> +	uint8_t msg[MAX_CEC_MSG_LEN];
> +} __packed;
> +
> +/* Set various CEC parameters */
> +#define EC_CMD_CEC_SET 0x00BA
> +
> +struct ec_params_cec_set {
> +	uint8_t cmd; /* enum cec_command */
> +	union {
> +		uint8_t enable;
> +		uint8_t address;
> +	};
> +} __packed;
> +
> +/* Read various CEC parameters */
> +#define EC_CMD_CEC_GET 0x00BB
> +
> +struct ec_params_cec_get {
> +	uint8_t cmd; /* enum cec_command */
> +} __packed;
> +
> +struct ec_response_cec_get {
> +	union {
> +		uint8_t enable;
> +		uint8_t address;
> +	};
> +} __packed;
> +
> +enum cec_command {
> +	/* CEC reading, writing and events enable */
> +	CEC_CMD_ENABLE,
> +	/* CEC logical address  */
> +	CEC_CMD_LOGICAL_ADDRESS,
> +};
> +
> +/* Events from CEC to AP */
> +enum mkbp_cec_event {
> +	EC_MKBP_CEC_SEND_OK			= 1 << 0,
> +	EC_MKBP_CEC_SEND_FAILED			= 1 << 1,
> +};
>  
>  /*****************************************************************************/
>  /*
>