[PATCH v12 03/10] drm/display: Add Type-C switch helpers

Pin-yen Lin
2023-02-21T09:51:50Z

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 v12:
- Add fwnode_for_each_typec_mode_switch macro
- Remove a duplicated dmesg in the helper
- Used IS_REACHABLE instead to guard the function signatures

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 | 108 ++++++++++++++++++
include/drm/display/drm_dp_helper.h | 35 ++++++
3 files changed, 144 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..161e4110f6b9
--- /dev/null
+++ b/drivers/gpu/drm/display/drm_dp_typec_helper.c
@@ -0,0 +1,108 @@
+// 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_typec_mode_switch(port, sw)
+ 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_typec_mode_switch(port, sw) {
+ 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);
+ 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..d2ac4be09c8e 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 +764,38 @@ 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;
+};
+
+#define fwnode_for_each_typec_mode_switch(port, sw) \
+ fwnode_for_each_child_node((port), (sw)) \
+ for_each_if(fwnode_property_present((sw), "mode-switch"))
+
+#if IS_REACHABLE(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_ */
--
2.39.2.637.g21b0678d19-goog