Re: [PATCH net] ptp: ocp: adjust sysfs entries to expose tty information

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Aug 02, 2024 at 08:46:34AM -0700, Vadim Fedorenko wrote:
> Starting v6.8 the serial port subsystem changed the hierarchy of devices
> and symlinks are not working anymore. Previous discussion made it clear
> that the idea of symlinks for tty devices was wrong by design. Implement
> additional attributes to expose the information. Fixes tag points to the
> commit which introduced the change.
> 
> Fixes: b286f4e87e32 ("serial: core: Move tty and serdev to be children of serial core port device")
> Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
> ---
>  drivers/ptp/ptp_ocp.c | 68 +++++++++++++++++++++++++++++++++----------
>  1 file changed, 52 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
> index ee2ced88ab34..7a5026656452 100644
> --- a/drivers/ptp/ptp_ocp.c
> +++ b/drivers/ptp/ptp_ocp.c
> @@ -3346,6 +3346,55 @@ static EXT_ATTR_RO(freq, frequency, 1);
>  static EXT_ATTR_RO(freq, frequency, 2);
>  static EXT_ATTR_RO(freq, frequency, 3);
>  
> +static ssize_t
> +ptp_ocp_tty_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct dev_ext_attribute *ea = to_ext_attr(attr);
> +	struct ptp_ocp *bp = dev_get_drvdata(dev);
> +	struct ptp_ocp_serial_port *port;
> +
> +	port = (void *)((uintptr_t)bp + (uintptr_t)ea->var);
> +	return sysfs_emit(buf, "ttyS%d", port->line);
> +}
> +
> +static umode_t
> +ptp_ocp_timecard_tty_is_visible(struct kobject *kobj, struct attribute *attr, int n)
> +{
> +	struct ptp_ocp *bp = dev_get_drvdata(kobj_to_dev(kobj));
> +	struct ptp_ocp_serial_port *port;
> +	struct device_attribute *dattr;
> +	struct dev_ext_attribute *ea;
> +
> +	if (strncmp(attr->name, "tty", 3))
> +		return attr->mode;
> +
> +	dattr = container_of(attr, struct device_attribute, attr);
> +	ea = container_of(dattr, struct dev_ext_attribute, attr);
> +	port = (void *)((uintptr_t)bp + (uintptr_t)ea->var);
> +	return port->line == -1 ? 0 : 0444;
> +}
> +#define EXT_TTY_ATTR_RO(_name, _val)			\
> +	struct dev_ext_attribute dev_attr_tty##_name =	\
> +		{ __ATTR(tty##_name, 0444, ptp_ocp_tty_show, NULL), (void *)_val }
> +
> +static EXT_TTY_ATTR_RO(GNSS, offsetof(struct ptp_ocp, gnss_port));
> +static EXT_TTY_ATTR_RO(GNSS2, offsetof(struct ptp_ocp, gnss2_port));
> +static EXT_TTY_ATTR_RO(MAC, offsetof(struct ptp_ocp, mac_port));
> +static EXT_TTY_ATTR_RO(NMEA, offsetof(struct ptp_ocp, nmea_port));
> +static struct attribute *ptp_ocp_timecard_tty_attrs[] = {
> +	&dev_attr_ttyGNSS.attr.attr,
> +	&dev_attr_ttyGNSS2.attr.attr,
> +	&dev_attr_ttyMAC.attr.attr,
> +	&dev_attr_ttyNMEA.attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group ptp_ocp_timecard_tty_group = {
> +	.name = "tty",
> +	.attrs = ptp_ocp_timecard_tty_attrs,
> +	.is_visible = ptp_ocp_timecard_tty_is_visible,
> +};
> +
>  static ssize_t
>  serialnum_show(struct device *dev, struct device_attribute *attr, char *buf)
>  {
> @@ -3775,6 +3824,7 @@ static const struct attribute_group fb_timecard_group = {
>  
>  static const struct ocp_attr_group fb_timecard_groups[] = {
>  	{ .cap = OCP_CAP_BASIC,	    .group = &fb_timecard_group },
> +	{ .cap = OCP_CAP_BASIC,	    .group = &ptp_ocp_timecard_tty_group },
>  	{ .cap = OCP_CAP_SIGNAL,    .group = &fb_timecard_signal0_group },
>  	{ .cap = OCP_CAP_SIGNAL,    .group = &fb_timecard_signal1_group },
>  	{ .cap = OCP_CAP_SIGNAL,    .group = &fb_timecard_signal2_group },
> @@ -3814,6 +3864,7 @@ static const struct attribute_group art_timecard_group = {
>  
>  static const struct ocp_attr_group art_timecard_groups[] = {
>  	{ .cap = OCP_CAP_BASIC,	    .group = &art_timecard_group },
> +	{ .cap = OCP_CAP_BASIC,	    .group = &ptp_ocp_timecard_tty_group },
>  	{ },
>  };
>  
> @@ -3841,6 +3892,7 @@ static const struct attribute_group adva_timecard_group = {
>  
>  static const struct ocp_attr_group adva_timecard_groups[] = {
>  	{ .cap = OCP_CAP_BASIC,	    .group = &adva_timecard_group },
> +	{ .cap = OCP_CAP_BASIC,	    .group = &ptp_ocp_timecard_tty_group },
>  	{ .cap = OCP_CAP_SIGNAL,    .group = &fb_timecard_signal0_group },
>  	{ .cap = OCP_CAP_SIGNAL,    .group = &fb_timecard_signal1_group },
>  	{ .cap = OCP_CAP_FREQ,	    .group = &fb_timecard_freq0_group },
> @@ -4352,22 +4404,6 @@ ptp_ocp_complete(struct ptp_ocp *bp)
>  	struct pps_device *pps;
>  	char buf[32];
>  
> -	if (bp->gnss_port.line != -1) {
> -		sprintf(buf, "ttyS%d", bp->gnss_port.line);
> -		ptp_ocp_link_child(bp, buf, "ttyGNSS");
> -	}
> -	if (bp->gnss2_port.line != -1) {
> -		sprintf(buf, "ttyS%d", bp->gnss2_port.line);
> -		ptp_ocp_link_child(bp, buf, "ttyGNSS2");
> -	}
> -	if (bp->mac_port.line != -1) {
> -		sprintf(buf, "ttyS%d", bp->mac_port.line);
> -		ptp_ocp_link_child(bp, buf, "ttyMAC");
> -	}
> -	if (bp->nmea_port.line != -1) {
> -		sprintf(buf, "ttyS%d", bp->nmea_port.line);
> -		ptp_ocp_link_child(bp, buf, "ttyNMEA");
> -	}
>  	sprintf(buf, "ptp%d", ptp_clock_index(bp->ptp));
>  	ptp_ocp_link_child(bp, buf, "ptp");
>  
> -- 
> 2.43.5
> 

Hi,

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