[PATCH net v4 1/2] ptp: ocp: adjust sysfs entries to expose tty information

[PATCH net v4 1/2] ptp: ocp: adjust sysfs entries to expose tty information

[Vadim Fedorenko]

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 [1].
Implement additional attributes to expose the information. Fixes tag
points to the commit which introduced the change.

[1] https://lore.kernel.org/netdev/2024060503-subsonic-pupil-bbee@gregkh/

Fixes: b286f4e87e32 ("serial: core: Move tty and serdev to be children of serial core port device")
Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
---
v3 -> v4:
- re-organize info printing to use ptp_ocp_tty_port_name()
- keep uintptr_t to be consistent with other code
v2 -> v3:
- replace serial ports definitions with array and enum for index
- replace pointer math with direct array access
- nit in documentation spelling
v1 -> v2:
- add Documentation/ABI changes
---
 drivers/ptp/ptp_ocp.c | 168 +++++++++++++++++++++++++-----------------
 1 file changed, 102 insertions(+), 66 deletions(-)

diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
index ee2ced88ab34..11d96045e5ec 100644
--- a/drivers/ptp/ptp_ocp.c
+++ b/drivers/ptp/ptp_ocp.c
@@ -316,6 +316,15 @@ struct ptp_ocp_serial_port {
 #define OCP_SERIAL_LEN			6
 #define OCP_SMA_NUM			4
 
+enum {
+	PORT_GNSS,
+	PORT_GNSS2,
+	PORT_MAC, /* miniature atomic clock */
+	PORT_NMEA,
+
+	__PORT_COUNT,
+};
+
 struct ptp_ocp {
 	struct pci_dev		*pdev;
 	struct device		dev;
@@ -357,10 +366,7 @@ struct ptp_ocp {
 	struct delayed_work	sync_work;
 	int			id;
 	int			n_irqs;
-	struct ptp_ocp_serial_port	gnss_port;
-	struct ptp_ocp_serial_port	gnss2_port;
-	struct ptp_ocp_serial_port	mac_port;   /* miniature atomic clock */
-	struct ptp_ocp_serial_port	nmea_port;
+	struct ptp_ocp_serial_port	port[__PORT_COUNT];
 	bool			fw_loader;
 	u8			fw_tag;
 	u16			fw_version;
@@ -655,28 +661,28 @@ static struct ocp_resource ocp_fb_resource[] = {
 		},
 	},
 	{
-		OCP_SERIAL_RESOURCE(gnss_port),
+		OCP_SERIAL_RESOURCE(port[PORT_GNSS]),
 		.offset = 0x00160000 + 0x1000, .irq_vec = 3,
 		.extra = &(struct ptp_ocp_serial_port) {
 			.baud = 115200,
 		},
 	},
 	{
-		OCP_SERIAL_RESOURCE(gnss2_port),
+		OCP_SERIAL_RESOURCE(port[PORT_GNSS2]),
 		.offset = 0x00170000 + 0x1000, .irq_vec = 4,
 		.extra = &(struct ptp_ocp_serial_port) {
 			.baud = 115200,
 		},
 	},
 	{
-		OCP_SERIAL_RESOURCE(mac_port),
+		OCP_SERIAL_RESOURCE(port[PORT_MAC]),
 		.offset = 0x00180000 + 0x1000, .irq_vec = 5,
 		.extra = &(struct ptp_ocp_serial_port) {
 			.baud = 57600,
 		},
 	},
 	{
-		OCP_SERIAL_RESOURCE(nmea_port),
+		OCP_SERIAL_RESOURCE(port[PORT_NMEA]),
 		.offset = 0x00190000 + 0x1000, .irq_vec = 10,
 	},
 	{
@@ -740,7 +746,7 @@ static struct ocp_resource ocp_art_resource[] = {
 		.offset = 0x01000000, .size = 0x10000,
 	},
 	{
-		OCP_SERIAL_RESOURCE(gnss_port),
+		OCP_SERIAL_RESOURCE(port[PORT_GNSS]),
 		.offset = 0x00160000 + 0x1000, .irq_vec = 3,
 		.extra = &(struct ptp_ocp_serial_port) {
 			.baud = 115200,
@@ -839,7 +845,7 @@ static struct ocp_resource ocp_art_resource[] = {
 		},
 	},
 	{
-		OCP_SERIAL_RESOURCE(mac_port),
+		OCP_SERIAL_RESOURCE(port[PORT_MAC]),
 		.offset = 0x00190000, .irq_vec = 7,
 		.extra = &(struct ptp_ocp_serial_port) {
 			.baud = 9600,
@@ -950,14 +956,14 @@ static struct ocp_resource ocp_adva_resource[] = {
 		.offset = 0x00220000, .size = 0x1000,
 	},
 	{
-		OCP_SERIAL_RESOURCE(gnss_port),
+		OCP_SERIAL_RESOURCE(port[PORT_GNSS]),
 		.offset = 0x00160000 + 0x1000, .irq_vec = 3,
 		.extra = &(struct ptp_ocp_serial_port) {
 			.baud = 9600,
 		},
 	},
 	{
-		OCP_SERIAL_RESOURCE(mac_port),
+		OCP_SERIAL_RESOURCE(port[PORT_MAC]),
 		.offset = 0x00180000 + 0x1000, .irq_vec = 5,
 		.extra = &(struct ptp_ocp_serial_port) {
 			.baud = 115200,
@@ -1649,6 +1655,15 @@ ptp_ocp_tod_gnss_name(int idx)
 	return gnss_name[idx];
 }
 
+static const char *
+ptp_ocp_tty_port_name(int idx)
+{
+	static const char * const tty_name[] = {
+		"GNSS", "GNSS2", "MAC", "NMEA"
+	};
+	return tty_name[idx];
+}
+
 struct ptp_ocp_nvmem_match_info {
 	struct ptp_ocp *bp;
 	const void * const tag;
@@ -3346,6 +3361,54 @@ 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;
+
+	return sysfs_emit(buf, "ttyS%d", bp->port[(uintptr_t)ea->var].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 = &bp->port[(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, PORT_GNSS);
+static EXT_TTY_ATTR_RO(GNSS2, PORT_GNSS2);
+static EXT_TTY_ATTR_RO(MAC, PORT_MAC);
+static EXT_TTY_ATTR_RO(NMEA, PORT_NMEA);
+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 +3838,7 @@ 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 +3878,7 @@ 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 +3906,7 @@ 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 },
@@ -3960,16 +4026,11 @@ ptp_ocp_summary_show(struct seq_file *s, void *data)
 	bp = dev_get_drvdata(dev);
 
 	seq_printf(s, "%7s: /dev/ptp%d\n", "PTP", ptp_clock_index(bp->ptp));
-	if (bp->gnss_port.line != -1)
-		seq_printf(s, "%7s: /dev/ttyS%d\n", "GNSS1",
-			   bp->gnss_port.line);
-	if (bp->gnss2_port.line != -1)
-		seq_printf(s, "%7s: /dev/ttyS%d\n", "GNSS2",
-			   bp->gnss2_port.line);
-	if (bp->mac_port.line != -1)
-		seq_printf(s, "%7s: /dev/ttyS%d\n", "MAC", bp->mac_port.line);
-	if (bp->nmea_port.line != -1)
-		seq_printf(s, "%7s: /dev/ttyS%d\n", "NMEA", bp->nmea_port.line);
+	for (i = 0; i < __PORT_COUNT; i++) {
+		if (bp->port[i].line != -1)
+			seq_printf(s, "%7s: /dev/ttyS%d\n", ptp_ocp_tty_port_name(i),
+				   bp->port[i].line);
+	}
 
 	memset(sma_val, 0xff, sizeof(sma_val));
 	if (bp->sma_map1) {
@@ -4279,7 +4340,7 @@ ptp_ocp_dev_release(struct device *dev)
 static int
 ptp_ocp_device_init(struct ptp_ocp *bp, struct pci_dev *pdev)
 {
-	int err;
+	int i, err;
 
 	mutex_lock(&ptp_ocp_lock);
 	err = idr_alloc(&ptp_ocp_idr, bp, 0, 0, GFP_KERNEL);
@@ -4292,10 +4353,10 @@ ptp_ocp_device_init(struct ptp_ocp *bp, struct pci_dev *pdev)
 
 	bp->ptp_info = ptp_ocp_clock_info;
 	spin_lock_init(&bp->lock);
-	bp->gnss_port.line = -1;
-	bp->gnss2_port.line = -1;
-	bp->mac_port.line = -1;
-	bp->nmea_port.line = -1;
+
+	for (i = 0; i < __PORT_COUNT; i++)
+		bp->port[i].line = -1;
+
 	bp->pdev = pdev;
 
 	device_initialize(&bp->dev);
@@ -4352,22 +4413,6 @@ 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");
 
@@ -4416,23 +4461,22 @@ ptp_ocp_info(struct ptp_ocp *bp)
 	};
 	struct device *dev = &bp->pdev->dev;
 	u32 reg;
+	int i;
 
 	ptp_ocp_phc_info(bp);
 
-	ptp_ocp_serial_info(dev, "GNSS", bp->gnss_port.line,
-			    bp->gnss_port.baud);
-	ptp_ocp_serial_info(dev, "GNSS2", bp->gnss2_port.line,
-			    bp->gnss2_port.baud);
-	ptp_ocp_serial_info(dev, "MAC", bp->mac_port.line, bp->mac_port.baud);
-	if (bp->nmea_out && bp->nmea_port.line != -1) {
-		bp->nmea_port.baud = -1;
+	for (i = 0; i < __PORT_COUNT; i++) {
+		if (i == PORT_NMEA && bp->nmea_out && bp->port[PORT_NMEA].line != -1) {
+			bp->port[PORT_NMEA].baud = -1;
+
+			reg = ioread32(&bp->nmea_out->uart_baud);
+			if (reg < ARRAY_SIZE(nmea_baud))
+				bp->port[PORT_NMEA].baud = nmea_baud[reg];
+		}
+		ptp_ocp_serial_info(dev, ptp_ocp_tty_port_name(i), bp->port[i].line,
+				    bp->port[i].baud);
 
-		reg = ioread32(&bp->nmea_out->uart_baud);
-		if (reg < ARRAY_SIZE(nmea_baud))
-			bp->nmea_port.baud = nmea_baud[reg];
 
-		ptp_ocp_serial_info(dev, "NMEA", bp->nmea_port.line,
-				    bp->nmea_port.baud);
 	}
 }
 
@@ -4441,9 +4485,6 @@ ptp_ocp_detach_sysfs(struct ptp_ocp *bp)
 {
 	struct device *dev = &bp->dev;
 
-	sysfs_remove_link(&dev->kobj, "ttyGNSS");
-	sysfs_remove_link(&dev->kobj, "ttyGNSS2");
-	sysfs_remove_link(&dev->kobj, "ttyMAC");
 	sysfs_remove_link(&dev->kobj, "ptp");
 	sysfs_remove_link(&dev->kobj, "pps");
 }
@@ -4473,14 +4514,9 @@ ptp_ocp_detach(struct ptp_ocp *bp)
 	for (i = 0; i < 4; i++)
 		if (bp->signal_out[i])
 			ptp_ocp_unregister_ext(bp->signal_out[i]);
-	if (bp->gnss_port.line != -1)
-		serial8250_unregister_port(bp->gnss_port.line);
-	if (bp->gnss2_port.line != -1)
-		serial8250_unregister_port(bp->gnss2_port.line);
-	if (bp->mac_port.line != -1)
-		serial8250_unregister_port(bp->mac_port.line);
-	if (bp->nmea_port.line != -1)
-		serial8250_unregister_port(bp->nmea_port.line);
+	for (i = 0; i < __PORT_COUNT; i++)
+		if (bp->port[i].line != -1)
+			serial8250_unregister_port(bp->port[i].line);
 	platform_device_unregister(bp->spi_flash);
 	platform_device_unregister(bp->i2c_ctrl);
 	if (bp->i2c_clk)
-- 
2.43.5

[PATCH net v4 2/2] docs: ABI: update OCP TimeCard sysfs entries

[Vadim Fedorenko]

Update documentation according to the changes in the driver.

New attributes group tty is exposed and ttyGNSS, ttyGNSS2, ttyMAC and
ttyNMEA are moved to this group. Also, these attributes are no more
links to the devices but rather simple text files containing names of
tty devices.

Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
---
 Documentation/ABI/testing/sysfs-timecard | 31 ++++++++++++++----------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-timecard b/Documentation/ABI/testing/sysfs-timecard
index 220478156297..3ae41b7634ac 100644
--- a/Documentation/ABI/testing/sysfs-timecard
+++ b/Documentation/ABI/testing/sysfs-timecard
@@ -258,24 +258,29 @@ Description:	(RW) When retrieving the PHC with the PTP SYS_OFFSET_EXTENDED
 		the estimated point where the FPGA latches the PHC time.  This
 		value may be changed by writing an unsigned integer.
 
-What:		/sys/class/timecard/ocpN/ttyGNSS
-What:		/sys/class/timecard/ocpN/ttyGNSS2
-Date:		September 2021
+What:		/sys/class/timecard/ocpN/tty
+Date:		August 2024
+Contact:	Vadim Fedorenko <vadim.fedorenko@linux.dev>
+Description:	(RO) Directory containing the sysfs nodes for TTY attributes
+
+What:		/sys/class/timecard/ocpN/tty/ttyGNSS
+What:		/sys/class/timecard/ocpN/tty/ttyGNSS2
+Date:		August 2024
 Contact:	Jonathan Lemon <jonathan.lemon@gmail.com>
-Description:	These optional attributes link to the TTY serial ports
-		associated with the GNSS devices.
+Description:	(RO) These optional attributes contain names of the TTY serial
+		ports associated with the GNSS devices.
 
-What:		/sys/class/timecard/ocpN/ttyMAC
-Date:		September 2021
+What:		/sys/class/timecard/ocpN/tty/ttyMAC
+Date:		August 2024
 Contact:	Jonathan Lemon <jonathan.lemon@gmail.com>
-Description:	This optional attribute links to the TTY serial port
-		associated with the Miniature Atomic Clock.
+Description:	(RO) This optional attribute contains name of the TTY serial
+		port associated with the Miniature Atomic Clock.
 
-What:		/sys/class/timecard/ocpN/ttyNMEA
-Date:		September 2021
+What:		/sys/class/timecard/ocpN/tty/ttyNMEA
+Date:		August 2024
 Contact:	Jonathan Lemon <jonathan.lemon@gmail.com>
-Description:	This optional attribute links to the TTY serial port
-		which outputs the PHC time in NMEA ZDA format.
+Description:	(RO) This optional attribute contains name of the TTY serial
+		port which outputs the PHC time in NMEA ZDA format.
 
 What:		/sys/class/timecard/ocpN/utc_tai_offset
 Date:		September 2021
-- 
2.43.5

Re: [PATCH net v4 1/2] ptp: ocp: adjust sysfs entries to expose tty information

[Vadim Fedorenko]

On 20/08/2024 16:16, 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 [1].
> Implement additional attributes to expose the information. Fixes tag
> points to the commit which introduced the change.
> 
> [1] https://lore.kernel.org/netdev/2024060503-subsonic-pupil-bbee@gregkh/
> 
> Fixes: b286f4e87e32 ("serial: core: Move tty and serdev to be children of serial core port device")
> Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
> ---
> v3 -> v4:
> - re-organize info printing to use ptp_ocp_tty_port_name()
> - keep uintptr_t to be consistent with other code
> v2 -> v3:
> - replace serial ports definitions with array and enum for index
> - replace pointer math with direct array access
> - nit in documentation spelling
> v1 -> v2:
> - add Documentation/ABI changes
> ---
>   drivers/ptp/ptp_ocp.c | 168 +++++++++++++++++++++++++-----------------
>   1 file changed, 102 insertions(+), 66 deletions(-)
> 
> diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c
> index ee2ced88ab34..11d96045e5ec 100644
> --- a/drivers/ptp/ptp_ocp.c
> +++ b/drivers/ptp/ptp_ocp.c

[ .. snip .. ]

> @@ -3346,6 +3361,54 @@ 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;

looks like this fix didn't get to the series for some reasons.
I'll definitely send v5 with this part removed, but other code
is good to review

> +
> +	return sysfs_emit(buf, "ttyS%d", bp->port[(uintptr_t)ea->var].line);
> +}
> +