[PATCH v3 5/5] drm: bridge: Generic GPIO mux driver
Pin-yen Lin
treapking at chromium.org
Sat Feb 18 03:17:12 PST 2023
From: Nicolas Boichat <drinkcat at chromium.org>
This driver supports single input, 2 output display mux (e.g.
HDMI mux), that provide its status via a GPIO.
Signed-off-by: Nicolas Boichat <drinkcat at chromium.org>
Signed-off-by: Pin-yen Lin <treapking at chromium.org>
---
Changes in v3:
- Added .get_edid callback in generic-gpio-mux driver
Changes in v2:
- Dropped attach/mode_set/enable/disable callbacks
- Fixed style issues
- Removed the special case for the HDMI connector
- Made the driver only read the GPIO status in IRQ handler
- Rebased to drm-misc-next
- Update the license: "GPL v2" --> "GPL"
drivers/gpu/drm/bridge/Kconfig | 10 +
drivers/gpu/drm/bridge/Makefile | 1 +
drivers/gpu/drm/bridge/generic-gpio-mux.c | 222 ++++++++++++++++++++++
3 files changed, 233 insertions(+)
create mode 100644 drivers/gpu/drm/bridge/generic-gpio-mux.c
diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index 12e8f30c65f7..42d7c418e8ff 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -73,6 +73,16 @@ config DRM_FSL_LDB
help
Support for i.MX8MP DPI-to-LVDS on-SoC encoder.
+config DRM_GENERIC_GPIO_MUX
+ tristate "Generic GPIO-controlled mux"
+ depends on OF
+ select DRM_KMS_HELPER
+ help
+ This bridge driver models a GPIO-controlled display mux with one
+ input, 2 outputs (e.g. an HDMI mux). The hardware decides which output
+ is active, reports it as a GPIO, and the driver redirects calls to the
+ appropriate downstream bridge (if any).
+
config DRM_ITE_IT6505
tristate "ITE IT6505 DisplayPort bridge"
depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 52f6e8b4a821..4d6d7f63330c 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
obj-$(CONFIG_DRM_CROS_EC_ANX7688) += cros-ec-anx7688.o
obj-$(CONFIG_DRM_DISPLAY_CONNECTOR) += display-connector.o
obj-$(CONFIG_DRM_FSL_LDB) += fsl-ldb.o
+obj-$(CONFIG_DRM_GENERIC_GPIO_MUX) += generic-gpio-mux.o
obj-$(CONFIG_DRM_ITE_IT6505) += ite-it6505.o
obj-$(CONFIG_DRM_LONTIUM_LT8912B) += lontium-lt8912b.o
obj-$(CONFIG_DRM_LONTIUM_LT9211) += lontium-lt9211.o
diff --git a/drivers/gpu/drm/bridge/generic-gpio-mux.c b/drivers/gpu/drm/bridge/generic-gpio-mux.c
new file mode 100644
index 000000000000..928edde701fa
--- /dev/null
+++ b/drivers/gpu/drm/bridge/generic-gpio-mux.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic gpio mux bridge driver
+ *
+ * Copyright 2016 Google LLC
+ */
+
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/of_graph.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_bridge.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_probe_helper.h>
+
+struct gpio_display_mux {
+ struct device *dev;
+
+ struct gpio_desc *gpiod_detect;
+ int detect_irq;
+ int cur_next;
+
+ struct drm_bridge bridge;
+
+ struct drm_bridge *next[2];
+};
+
+static inline struct gpio_display_mux *bridge_to_gpio_display_mux(
+ struct drm_bridge *bridge)
+{
+ return container_of(bridge, struct gpio_display_mux, bridge);
+}
+
+static irqreturn_t gpio_display_mux_det_threaded_handler(int unused, void *data)
+{
+ struct gpio_display_mux *mux = data;
+ int active = gpiod_get_value(mux->gpiod_detect);
+
+ if (active < 0) {
+ dev_err(mux->dev, "Failed to get detect GPIO\n");
+ return IRQ_HANDLED;
+ }
+
+ dev_dbg(mux->dev, "Interrupt %d!\n", active);
+ mux->cur_next = active;
+
+ if (mux->bridge.dev)
+ drm_kms_helper_hotplug_event(mux->bridge.dev);
+
+ return IRQ_HANDLED;
+}
+
+static bool gpio_display_mux_mode_fixup(struct drm_bridge *bridge,
+ const struct drm_display_mode *mode,
+ struct drm_display_mode *adjusted_mode)
+{
+ struct gpio_display_mux *mux = bridge_to_gpio_display_mux(bridge);
+ struct drm_bridge *next;
+
+ next = mux->next[mux->cur_next];
+
+ /* Assume that we have a most one bridge in both downstreams */
+ if (next && next->funcs->mode_fixup)
+ return next->funcs->mode_fixup(next, mode, adjusted_mode);
+
+ return true;
+}
+
+static struct edid *gpio_display_mux_get_edid(struct drm_bridge *bridge,
+ struct drm_connector *connector)
+{
+ struct gpio_display_mux *mux = bridge_to_gpio_display_mux(bridge);
+ struct drm_bridge *next;
+
+ next = mux->next[mux->cur_next];
+
+ return next->funcs->get_edid(next, connector);
+}
+
+static const struct drm_bridge_funcs gpio_display_mux_bridge_funcs = {
+ .mode_fixup = gpio_display_mux_mode_fixup,
+ .get_edid = gpio_display_mux_get_edid,
+};
+
+static int gpio_display_mux_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct gpio_display_mux *mux;
+ struct device_node *port, *ep, *remote;
+ int ret;
+ u32 reg;
+
+ mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
+ if (!mux)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, mux);
+ mux->dev = &pdev->dev;
+
+ mux->bridge.of_node = dev->of_node;
+
+ mux->gpiod_detect = devm_gpiod_get(dev, "detect", GPIOD_IN);
+ if (IS_ERR(mux->gpiod_detect))
+ return PTR_ERR(mux->gpiod_detect);
+
+ mux->detect_irq = gpiod_to_irq(mux->gpiod_detect);
+ if (mux->detect_irq < 0) {
+ dev_err(dev, "Failed to get output irq %d\n",
+ mux->detect_irq);
+ return -ENODEV;
+ }
+
+ port = of_graph_get_port_by_id(dev->of_node, 1);
+ if (!port) {
+ dev_err(dev, "Missing output port node\n");
+ return -EINVAL;
+ }
+
+ for_each_child_of_node(port, ep) {
+ if (!ep->name || (of_node_cmp(ep->name, "endpoint") != 0)) {
+ of_node_put(ep);
+ continue;
+ }
+
+ if (of_property_read_u32(ep, "reg", ®) < 0 ||
+ reg >= ARRAY_SIZE(mux->next)) {
+ dev_err(dev,
+ "Missing/invalid reg property for endpoint %s\n",
+ ep->full_name);
+ of_node_put(ep);
+ of_node_put(port);
+ return -EINVAL;
+ }
+
+ remote = of_graph_get_remote_port_parent(ep);
+ if (!remote) {
+ dev_err(dev,
+ "Missing connector/bridge node for endpoint %s\n",
+ ep->full_name);
+ of_node_put(ep);
+ of_node_put(port);
+ return -EINVAL;
+ }
+
+ mux->next[reg] = of_drm_find_bridge(remote);
+ if (!mux->next[reg]) {
+ dev_err(dev, "Waiting for external bridge %s\n",
+ remote->name);
+ of_node_put(ep);
+ of_node_put(remote);
+ of_node_put(port);
+ return -EPROBE_DEFER;
+ }
+
+ of_node_put(remote);
+ }
+ of_node_put(port);
+
+ /*
+ * Because the next bridges are not registered to the drm bridge chain,
+ * we have to set DRM_BRIDGE_OP_EDID here and trigger the .get_edid
+ * callbacks of the actual connectors.
+ */
+ if (mux->next[0] && mux->next[0]->ops & DRM_BRIDGE_OP_EDID &&
+ mux->next[1] && mux->next[1]->ops & DRM_BRIDGE_OP_EDID)
+ mux->bridge.ops |= DRM_BRIDGE_OP_EDID;
+
+ mux->bridge.funcs = &gpio_display_mux_bridge_funcs;
+ mux->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
+ drm_bridge_add(&mux->bridge);
+
+ ret = devm_request_threaded_irq(dev, mux->detect_irq, NULL,
+ gpio_display_mux_det_threaded_handler,
+ IRQF_TRIGGER_RISING |
+ IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+ "gpio-display-mux-det", mux);
+ if (ret) {
+ dev_err(dev, "Failed to request MUX_DET threaded irq\n");
+ goto err_bridge_remove;
+ }
+
+ return 0;
+
+err_bridge_remove:
+ drm_bridge_remove(&mux->bridge);
+
+ return ret;
+}
+
+static int gpio_display_mux_remove(struct platform_device *pdev)
+{
+ struct gpio_display_mux *mux = platform_get_drvdata(pdev);
+
+ disable_irq(mux->detect_irq);
+ drm_bridge_remove(&mux->bridge);
+
+ return 0;
+}
+
+static const struct of_device_id gpio_display_mux_match[] = {
+ { .compatible = "gpio-display-mux", },
+ {},
+};
+
+struct platform_driver gpio_display_mux_driver = {
+ .probe = gpio_display_mux_probe,
+ .remove = gpio_display_mux_remove,
+ .driver = {
+ .name = "gpio-display-mux",
+ .of_match_table = gpio_display_mux_match,
+ },
+};
+
+module_platform_driver(gpio_display_mux_driver);
+
+MODULE_DESCRIPTION("GPIO-controlled display mux");
+MODULE_AUTHOR("Nicolas Boichat <drinkcat at chromium.org>");
+MODULE_LICENSE("GPL");
--
2.39.2.637.g21b0678d19-goog
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