Add helpers to register and unregister Type-C "switches" for bridges
capable of switching their output between two downstream devices.

The helper registers USB Type-C mode switches when the "mode-switch"
and the "reg" properties are available in Device Tree.

Signed-off-by: Pin-yen Lin <treapking@chromium.org>

---

Changes in v11:
- Use fwnode helpers instead of DT
- Moved the helpers to a new file
- Use "reg" instead of "data-lanes" to determine the port number
- Dropped collected tags due to new changes

Changes in v10:
- Collected Reviewed-by and Tested-by tags
- Replaced "void *" with "typec_mux_set_fn_t" for mux_set callbacks
- Print out the node name when errors on parsing DT
- Use dev_dbg instead of dev_warn when no Type-C switch nodes available
- Made the return path of drm_dp_register_mode_switch clearer

Changes in v8:
- Fixed the build issue when CONFIG_TYPEC=m
- Fixed some style issues

Changes in v7:
- Extracted the common codes to a helper function
- New in v7

 drivers/gpu/drm/display/Makefile              |   1 +
 drivers/gpu/drm/display/drm_dp_typec_helper.c | 114 ++++++++++++++++++
 include/drm/display/drm_dp_helper.h           |  31 +++++
 3 files changed, 146 insertions(+)
 create mode 100644 drivers/gpu/drm/display/drm_dp_typec_helper.c

diff --git a/drivers/gpu/drm/display/Makefile b/drivers/gpu/drm/display/Makefile
index 17ac4a1006a8..ef80b9fde615 100644
--- a/drivers/gpu/drm/display/Makefile
+++ b/drivers/gpu/drm/display/Makefile
@@ -14,5 +14,6 @@ drm_display_helper-$(CONFIG_DRM_DISPLAY_HDMI_HELPER) += \
 	drm_scdc_helper.o
 drm_display_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o
 drm_display_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o
+drm_display_helper-$(CONFIG_TYPEC) += drm_dp_typec_helper.o
 
 obj-$(CONFIG_DRM_DISPLAY_HELPER) += drm_display_helper.o
diff --git a/drivers/gpu/drm/display/drm_dp_typec_helper.c b/drivers/gpu/drm/display/drm_dp_typec_helper.c
new file mode 100644
index 000000000000..b11a268da57f
--- /dev/null
+++ b/drivers/gpu/drm/display/drm_dp_typec_helper.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/usb/typec_mux.h>
+#include <drm/display/drm_dp_helper.h>
+
+static int drm_dp_register_mode_switch(struct device *dev,
+				       struct fwnode_handle *fwnode,
+				       struct drm_dp_typec_switch_desc *switch_desc,
+				       void *data, typec_mux_set_fn_t mux_set)
+{
+	struct drm_dp_typec_port_data *port_data;
+	struct typec_mux_desc mux_desc = {};
+	char name[32];
+	u32 port_num;
+	int ret;
+
+	ret = fwnode_property_read_u32(fwnode, "reg", &port_num);
+	if (ret) {
+		dev_err(dev, "Failed to read reg property: %d\n", ret);
+		return ret;
+	}
+
+	port_data = &switch_desc->typec_ports[port_num];
+	port_data->data = data;
+	port_data->port_num = port_num;
+	port_data->fwnode = fwnode;
+	mux_desc.fwnode = fwnode;
+	mux_desc.drvdata = port_data;
+	snprintf(name, sizeof(name), "%pfwP-%u", fwnode, port_num);
+	mux_desc.name = name;
+	mux_desc.set = mux_set;
+
+	port_data->typec_mux = typec_mux_register(dev, &mux_desc);
+	if (IS_ERR(port_data->typec_mux)) {
+		ret = PTR_ERR(port_data->typec_mux);
+		dev_err(dev, "Mode switch register for port %d failed: %d\n",
+			port_num, ret);
+
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * drm_dp_register_typec_switches() - register Type-C switches
+ * @dev: Device that registers Type-C switches
+ * @port: Device node for the switch
+ * @switch_desc: A Type-C switch descriptor
+ * @data: Private data for the switches
+ * @mux_set: Callback function for typec_mux_set
+ *
+ * This function registers USB Type-C switches for DP bridges that can switch
+ * the output signal between their output pins.
+ *
+ * Currently only mode switches are implemented, and the function assumes the
+ * given @port device node has endpoints with "mode-switch" property.
+ * The port number is determined by the "reg" property of the endpoint.
+ */
+int drm_dp_register_typec_switches(struct device *dev, struct fwnode_handle *port,
+				   struct drm_dp_typec_switch_desc *switch_desc,
+				   void *data, typec_mux_set_fn_t mux_set)
+{
+	struct fwnode_handle *sw;
+	int ret;
+
+	fwnode_for_each_child_node(port, sw) {
+		if (fwnode_property_present(sw, "mode-switch"))
+			switch_desc->num_typec_switches++;
+	}
+
+	if (!switch_desc->num_typec_switches) {
+		dev_dbg(dev, "No Type-C switches node found\n");
+		return 0;
+	}
+
+	switch_desc->typec_ports = devm_kcalloc(
+		dev, switch_desc->num_typec_switches,
+		sizeof(struct drm_dp_typec_port_data), GFP_KERNEL);
+
+	if (!switch_desc->typec_ports)
+		return -ENOMEM;
+
+	/* Register switches for each connector. */
+	fwnode_for_each_child_node(port, sw) {
+		if (!fwnode_property_present(sw, "mode-switch"))
+			continue;
+		ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
+		if (ret)
+			goto err_unregister_typec_switches;
+	}
+
+	return 0;
+
+err_unregister_typec_switches:
+	fwnode_handle_put(sw);
+	drm_dp_unregister_typec_switches(switch_desc);
+	dev_err(dev, "Failed to register mode switch: %d\n", ret);
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_register_typec_switches);
+
+/**
+ * drm_dp_unregister_typec_switches() - unregister Type-C switches
+ * @switch_desc: A Type-C switch descriptor
+ */
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
+{
+	int i;
+
+	for (i = 0; i < switch_desc->num_typec_switches; i++)
+		typec_mux_unregister(switch_desc->typec_ports[i].typec_mux);
+}
+EXPORT_SYMBOL(drm_dp_unregister_typec_switches);
diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index ab55453f2d2c..d9213739de72 100644
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -25,6 +25,7 @@
 
 #include <linux/delay.h>
 #include <linux/i2c.h>
+#include <linux/usb/typec_mux.h>
 
 #include <drm/display/drm_dp.h>
 #include <drm/drm_connector.h>
@@ -763,4 +764,34 @@ bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZ
 					       const u8 port_cap[4], u8 color_spc);
 int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc);
 
+struct drm_dp_typec_port_data {
+	struct typec_mux_dev *typec_mux;
+	int port_num;
+	struct fwnode_handle *fwnode;
+	void *data;
+};
+
+struct drm_dp_typec_switch_desc {
+	int num_typec_switches;
+	struct drm_dp_typec_port_data *typec_ports;
+};
+
+#ifdef CONFIG_TYPEC
+void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc);
+int drm_dp_register_typec_switches(struct device *dev, struct fwnode_handle *port,
+				   struct drm_dp_typec_switch_desc *switch_desc,
+				   void *data, typec_mux_set_fn_t mux_set);
+#else
+static inline void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
+{
+}
+static inline int drm_dp_register_typec_switches(
+		struct device *dev, struct fwnode_handle *port,
+		struct drm_dp_typec_switch_desc *switch_desc, void *data,
+		typec_mux_set_fn_t mux_set)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
 #endif /* _DRM_DP_HELPER_H_ */
-- 
2.39.1.519.gcb327c4b5f-goog

Hi Pin-yen,

[...]

> +static int drm_dp_register_mode_switch(struct device *dev,
> +				       struct fwnode_handle *fwnode,
> +				       struct drm_dp_typec_switch_desc *switch_desc,
> +				       void *data, typec_mux_set_fn_t mux_set)
> +{
> +	struct drm_dp_typec_port_data *port_data;
> +	struct typec_mux_desc mux_desc = {};
> +	char name[32];
> +	u32 port_num;
> +	int ret;
> +
> +	ret = fwnode_property_read_u32(fwnode, "reg", &port_num);
> +	if (ret) {
> +		dev_err(dev, "Failed to read reg property: %d\n", ret);
> +		return ret;
> +	}
> +
> +	port_data = &switch_desc->typec_ports[port_num];
> +	port_data->data = data;
> +	port_data->port_num = port_num;
> +	port_data->fwnode = fwnode;
> +	mux_desc.fwnode = fwnode;
> +	mux_desc.drvdata = port_data;
> +	snprintf(name, sizeof(name), "%pfwP-%u", fwnode, port_num);
> +	mux_desc.name = name;
> +	mux_desc.set = mux_set;
> +
> +	port_data->typec_mux = typec_mux_register(dev, &mux_desc);
> +	if (IS_ERR(port_data->typec_mux)) {
> +		ret = PTR_ERR(port_data->typec_mux);
> +		dev_err(dev, "Mode switch register for port %d failed: %d\n",
> +			port_num, ret);
> +
> +		return ret;

you don't need this return here...

> +	}
> +
> +	return 0;

Just "return ret;" here.

> +}
> +
> +/**
> + * drm_dp_register_typec_switches() - register Type-C switches
> + * @dev: Device that registers Type-C switches
> + * @port: Device node for the switch
> + * @switch_desc: A Type-C switch descriptor
> + * @data: Private data for the switches
> + * @mux_set: Callback function for typec_mux_set
> + *
> + * This function registers USB Type-C switches for DP bridges that can switch
> + * the output signal between their output pins.
> + *
> + * Currently only mode switches are implemented, and the function assumes the
> + * given @port device node has endpoints with "mode-switch" property.
> + * The port number is determined by the "reg" property of the endpoint.
> + */
> +int drm_dp_register_typec_switches(struct device *dev, struct fwnode_handle *port,
> +				   struct drm_dp_typec_switch_desc *switch_desc,
> +				   void *data, typec_mux_set_fn_t mux_set)
> +{
> +	struct fwnode_handle *sw;
> +	int ret;
> +
> +	fwnode_for_each_child_node(port, sw) {
> +		if (fwnode_property_present(sw, "mode-switch"))
> +			switch_desc->num_typec_switches++;
> +	}

no need for brackets here

> +
> +	if (!switch_desc->num_typec_switches) {
> +		dev_dbg(dev, "No Type-C switches node found\n");

dev_warn()?

> +		return 0;
> +	}
> +
> +	switch_desc->typec_ports = devm_kcalloc(
> +		dev, switch_desc->num_typec_switches,
> +		sizeof(struct drm_dp_typec_port_data), GFP_KERNEL);
> +
> +	if (!switch_desc->typec_ports)
> +		return -ENOMEM;
> +
> +	/* Register switches for each connector. */
> +	fwnode_for_each_child_node(port, sw) {
> +		if (!fwnode_property_present(sw, "mode-switch"))
> +			continue;
> +		ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
> +		if (ret)
> +			goto err_unregister_typec_switches;
> +	}
> +
> +	return 0;
> +
> +err_unregister_typec_switches:
> +	fwnode_handle_put(sw);
> +	drm_dp_unregister_typec_switches(switch_desc);
> +	dev_err(dev, "Failed to register mode switch: %d\n", ret);

there is a bit of dmesg spamming. Please choose where you want to
print the error, either in this function or in
drm_dp_register_mode_switch().

Andi

> +	return ret;
> +}
> +EXPORT_SYMBOL(drm_dp_register_typec_switches);

[...]

On Sat, Feb 04, 2023 at 09:30:34PM +0800, Pin-yen Lin wrote:
> Add helpers to register and unregister Type-C "switches" for bridges
> capable of switching their output between two downstream devices.
> 
> The helper registers USB Type-C mode switches when the "mode-switch"
> and the "reg" properties are available in Device Tree.

...

> +	fwnode_for_each_child_node(port, sw) {
> +		if (fwnode_property_present(sw, "mode-switch"))

This idiom is being used at least twice (in this code, haven't checked the rest
of the patches, though), perhaps

#define fwnode_for_each_typec_mode_switch(port, sw)			\
	fwnode_for_each_child_node(port, sw)				\
		if (!fwnode_property_present(sw, "mode-switch")) {} else

?

-- 
With Best Regards,
Andy Shevchenko

On Mon, 06 Feb 2023, Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> On Sat, Feb 04, 2023 at 09:30:34PM +0800, Pin-yen Lin wrote:
>> Add helpers to register and unregister Type-C "switches" for bridges
>> capable of switching their output between two downstream devices.
>> 
>> The helper registers USB Type-C mode switches when the "mode-switch"
>> and the "reg" properties are available in Device Tree.
>
> ...
>
>> +	fwnode_for_each_child_node(port, sw) {
>> +		if (fwnode_property_present(sw, "mode-switch"))
>
> This idiom is being used at least twice (in this code, haven't checked the rest
> of the patches, though), perhaps
>
> #define fwnode_for_each_typec_mode_switch(port, sw)			\
> 	fwnode_for_each_child_node(port, sw)				\
> 		if (!fwnode_property_present(sw, "mode-switch")) {} else
>
> ?

See for_each_if() in drm_util.h.


BR,
Jani.


-- 
Jani Nikula, Intel Open Source Graphics Center