[PATCH 2/3] cec-gpio: add HDMI CEC GPIO driver
Hans Verkuil
hverkuil at xs4all.nl
Wed Aug 2 08:42:41 UTC 2017
From: Hans Verkuil <hans.verkuil at cisco.com>
Add a simple HDMI CEC GPIO driver that sits on top of the cec-pin framework.
While I have heard of SoCs that use the GPIO pin for CEC (apparently an
early RockChip SoC used that), the main use-case of this driver is to
function as a debugging tool.
By connecting the CEC line to a GPIO pin on a Raspberry Pi 3 for example
it turns it into a CEC debugger and protocol analyzer.
With 'cec-ctl --monitor-pin' the CEC traffic can be analyzed.
But of course it can also be used with any hardware project where the
HDMI CEC pin is hooked up to a pull-up gpio pin.
Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
---
drivers/media/platform/Kconfig | 10 ++
drivers/media/platform/Makefile | 2 +
drivers/media/platform/cec-gpio/Makefile | 1 +
drivers/media/platform/cec-gpio/cec-gpio.c | 190 +++++++++++++++++++++++++++++
4 files changed, 203 insertions(+)
create mode 100644 drivers/media/platform/cec-gpio/Makefile
create mode 100644 drivers/media/platform/cec-gpio/cec-gpio.c
diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
index 0c741d12dbc9..681507727259 100644
--- a/drivers/media/platform/Kconfig
+++ b/drivers/media/platform/Kconfig
@@ -537,6 +537,16 @@ menuconfig CEC_PLATFORM_DRIVERS
if CEC_PLATFORM_DRIVERS
+config CEC_GPIO
+ tristate "Generic GPIO-based CEC driver"
+ depends on PREEMPT
+ select CEC_CORE
+ select CEC_PIN
+ ---help---
+ This is a generic GPIO-based CEC driver.
+ The CEC bus is present in the HDMI connector and enables communication
+ between compatible devices.
+
config VIDEO_SAMSUNG_S5P_CEC
tristate "Samsung S5P CEC driver"
depends on PLAT_S5P || ARCH_EXYNOS || COMPILE_TEST
diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
index 9beadc760467..d01cc1886ad1 100644
--- a/drivers/media/platform/Makefile
+++ b/drivers/media/platform/Makefile
@@ -26,6 +26,8 @@ obj-$(CONFIG_VIDEO_CODA) += coda/
obj-$(CONFIG_VIDEO_SH_VEU) += sh_veu.o
+obj-$(CONFIG_CEC_GPIO) += cec-gpio/
+
obj-$(CONFIG_VIDEO_MEM2MEM_DEINTERLACE) += m2m-deinterlace.o
obj-$(CONFIG_VIDEO_MUX) += video-mux.o
diff --git a/drivers/media/platform/cec-gpio/Makefile b/drivers/media/platform/cec-gpio/Makefile
new file mode 100644
index 000000000000..e82b258afa55
--- /dev/null
+++ b/drivers/media/platform/cec-gpio/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_CEC_GPIO) += cec-gpio.o
diff --git a/drivers/media/platform/cec-gpio/cec-gpio.c b/drivers/media/platform/cec-gpio/cec-gpio.c
new file mode 100644
index 000000000000..43e1d447ad98
--- /dev/null
+++ b/drivers/media/platform/cec-gpio/cec-gpio.c
@@ -0,0 +1,190 @@
+/*
+ * Copyright 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
+ *
+ * This program is free software; you may redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of_gpio.h>
+#include <media/cec-pin.h>
+
+struct cec_gpio {
+ struct cec_adapter *adap;
+ struct device *dev;
+ int gpio;
+ int irq;
+ bool is_low;
+ bool have_irq;
+};
+
+static bool cec_gpio_read(struct cec_adapter *adap)
+{
+ struct cec_gpio *cec = cec_get_drvdata(adap);
+
+ if (cec->is_low)
+ return false;
+ return gpio_get_value(cec->gpio);
+}
+
+static void cec_gpio_high(struct cec_adapter *adap)
+{
+ struct cec_gpio *cec = cec_get_drvdata(adap);
+
+ if (!cec->is_low)
+ return;
+ cec->is_low = false;
+ gpio_direction_input(cec->gpio);
+}
+
+static void cec_gpio_low(struct cec_adapter *adap)
+{
+ struct cec_gpio *cec = cec_get_drvdata(adap);
+
+ if (cec->is_low)
+ return;
+ if (WARN_ON_ONCE(cec->have_irq))
+ free_irq(cec->irq, cec);
+ cec->have_irq = false;
+ cec->is_low = true;
+ gpio_direction_output(cec->gpio, 0);
+}
+
+static irqreturn_t cec_gpio_irq_handler(int irq, void *priv)
+{
+ struct cec_gpio *cec = priv;
+
+ cec_pin_changed(cec->adap, gpio_get_value(cec->gpio));
+ return IRQ_HANDLED;
+}
+
+static bool cec_gpio_enable_irq(struct cec_adapter *adap)
+{
+ struct cec_gpio *cec = cec_get_drvdata(adap);
+
+ if (request_irq(cec->irq, cec_gpio_irq_handler,
+ IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+ adap->name, cec))
+ return false;
+ cec->have_irq = true;
+ return true;
+}
+
+static void cec_gpio_disable_irq(struct cec_adapter *adap)
+{
+ struct cec_gpio *cec = cec_get_drvdata(adap);
+
+ if (cec->have_irq)
+ free_irq(cec->irq, cec);
+ cec->have_irq = false;
+}
+
+static void cec_gpio_status(struct cec_adapter *adap, struct seq_file *file)
+{
+ struct cec_gpio *cec = cec_get_drvdata(adap);
+
+ seq_printf(file, "mode: %s\n", cec->is_low ? "low-drive" : "read");
+ if (cec->have_irq)
+ seq_printf(file, "using irq: %d\n", cec->irq);
+}
+
+static void cec_gpio_free(struct cec_adapter *adap)
+{
+ struct cec_gpio *cec = cec_get_drvdata(adap);
+
+ if (cec->have_irq)
+ cec_gpio_disable_irq(adap);
+}
+
+static const struct cec_pin_ops cec_gpio_pin_ops = {
+ .read = cec_gpio_read,
+ .low = cec_gpio_low,
+ .high = cec_gpio_high,
+ .enable_irq = cec_gpio_enable_irq,
+ .disable_irq = cec_gpio_disable_irq,
+ .status = cec_gpio_status,
+ .free = cec_gpio_free,
+};
+
+static int cec_gpio_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ enum of_gpio_flags hpd_gpio_flags;
+ struct cec_gpio *cec;
+ int ret;
+
+ cec = devm_kzalloc(dev, sizeof(*cec), GFP_KERNEL);
+ if (!cec)
+ return -ENOMEM;
+
+ cec->gpio = of_get_named_gpio_flags(dev->of_node,
+ "gpio", 0, &hpd_gpio_flags);
+ if (cec->gpio < 0)
+ return cec->gpio;
+
+ cec->irq = gpio_to_irq(cec->gpio);
+ gpio_direction_input(cec->gpio);
+ cec->dev = dev;
+
+ cec->adap = cec_pin_allocate_adapter(&cec_gpio_pin_ops,
+ cec, pdev->name, CEC_CAP_TRANSMIT | CEC_CAP_LOG_ADDRS |
+ CEC_CAP_PASSTHROUGH | CEC_CAP_RC | CEC_CAP_PHYS_ADDR |
+ CEC_CAP_MONITOR_ALL | CEC_CAP_MONITOR_PIN);
+ if (IS_ERR(cec->adap))
+ return PTR_ERR(cec->adap);
+
+ ret = cec_register_adapter(cec->adap, &pdev->dev);
+ if (ret) {
+ cec_delete_adapter(cec->adap);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, cec);
+ return 0;
+}
+
+static int cec_gpio_remove(struct platform_device *pdev)
+{
+ struct cec_gpio *cec = platform_get_drvdata(pdev);
+
+ cec_unregister_adapter(cec->adap);
+ return 0;
+}
+
+static const struct of_device_id cec_gpio_match[] = {
+ {
+ .compatible = "cec-gpio",
+ },
+ {},
+};
+MODULE_DEVICE_TABLE(of, cec_gpio_match);
+
+static struct platform_driver cec_gpio_pdrv = {
+ .probe = cec_gpio_probe,
+ .remove = cec_gpio_remove,
+ .driver = {
+ .name = "cec-gpio",
+ .of_match_table = cec_gpio_match,
+ },
+};
+
+module_platform_driver(cec_gpio_pdrv);
+
+MODULE_AUTHOR("Hans Verkuil <hans.verkuil at cisco.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("CEC GPIO driver");
--
2.13.2
More information about the dri-devel
mailing list