[RFC, WIP, v5 04/10] media: vidtv: add a bridge driver

Daniel W. S. Almeida
2020-05-15T21:49:00Z

Digital TV devices consist of several independent hardware components which
are controlled by different drivers.
Each media device is controlled by a group of cooperating drivers with the
bridge driver as the main driver.

This patch adds a bridge driver for the Virtual Digital TV driver [vidtv].

The bridge driver binds to the other drivers, that is, vidtv_tuner and
vidtv_demod and implements the digital demux logic, providing userspace
with a MPEG Transport Stream.

Move config structs to a common header so they can be used by the bridge
driver and by their respective drivers.

Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
---
drivers/media/test-drivers/vidtv/Makefile | 4 +-
.../media/test-drivers/vidtv/vidtv_bridg.c | 380 ++++++++++++++++++
.../media/test-drivers/vidtv/vidtv_bridg.h | 37 ++
3 files changed, 420 insertions(+), 1 deletion(-)
create mode 100644 drivers/media/test-drivers/vidtv/vidtv_bridg.c
create mode 100644 drivers/media/test-drivers/vidtv/vidtv_bridg.h

diff --git a/drivers/media/test-drivers/vidtv/Makefile b/drivers/media/test-drivers/vidtv/Makefile
index 36ba00ddc0d1e..e0bb1b3bedad6 100644
--- a/drivers/media/test-drivers/vidtv/Makefile
+++ b/drivers/media/test-drivers/vidtv/Makefile
@@ -1,3 +1,5 @@
# SPDX-License-Identifier: GPL-2.0

-obj-$(CONFIG_DVB_VIDTV) += vidtv_tuner.o vidtv_demod.o
+vidtv_bridge-objs = vidtv_bridg.o
+
+obj-$(CONFIG_DVB_VIDTV) += vidtv_tuner.o vidtv_demod.o vidtv_bridge.o
diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridg.c b/drivers/media/test-drivers/vidtv/vidtv_bridg.c
new file mode 100644
index 0000000000000..95e564b91d4d1
--- /dev/null
+++ b/drivers/media/test-drivers/vidtv/vidtv_bridg.c
@@ -0,0 +1,380 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The Virtual DTV test driver serves as a reference DVB driver and helps
+ * validate the existing APIs in the media subsystem. It can also aid
+ * developers working on userspace applications.
+ *
+ * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
+
+#include <linux/types.h>
+#include <linux/moduleparam.h>
+#include <linux/mutex.h>
+#include <linux/workqueue.h>
+#include <linux/time.h>
+#include "linux/printk.h"
+
+#include "vidtv_bridg.h"
+#include "vidtv_tuner.h"
+#include "vidtv_demod.h"
+
+#define TUNER_DEFAULT_ADDR 0x68
+#define DEMOD_DEFAULT_ADDR 0x60
+
+MODULE_AUTHOR("Daniel W. S. Almeida");
+MODULE_LICENSE("GPL");
+
+static unsigned int drop_tslock_prob_on_low_snr;
+module_param(drop_tslock_prob_on_low_snr, uint, 0);
+MODULE_PARM_DESC(drop_tslock_prob_on_low_snr,
+ "Probability of losing the TS lock if the signal quality is bad");
+
+static unsigned int recover_tslock_prob_on_good_snr;
+module_param(recover_tslock_prob_on_good_snr, uint, 0);
+MODULE_PARM_DESC(recover_tslock_prob_on_good_snr,
+ "Probability recovering the TS lock when the signal improves");
+
+static unsigned int mock_power_up_delay_msec;
+module_param(mock_power_up_delay_msec, uint, 0);
+MODULE_PARM_DESC(mock_power_up_delay_msec, "Simulate a power up delay");
+
+static unsigned int mock_tune_delay_msec;
+module_param(mock_tune_delay_msec, uint, 0);
+MODULE_PARM_DESC(mock_tune_delay_msec, "Simulate a tune delay");
+
+static unsigned int vidtv_valid_dvb_t_freqs[8];
+module_param_array(vidtv_valid_dvb_t_freqs, uint, NULL, 0);
+MODULE_PARM_DESC(vidtv_valid_dvb_t_freqs,
+ "Valid DVB-T frequencies to simulate");
+
+static unsigned int vidtv_valid_dvb_c_freqs[8];
+module_param_array(vidtv_valid_dvb_c_freqs, uint, NULL, 0);
+MODULE_PARM_DESC(vidtv_valid_dvb_c_freqs,
+ "Valid DVB-C frequencies to simulate");
+
+static unsigned int vidtv_valid_dvb_s_freqs[8];
+module_param_array(vidtv_valid_dvb_s_freqs, uint, NULL, 0);
+MODULE_PARM_DESC(vidtv_valid_dvb_s_freqs,
+ "Valid DVB-C frequencies to simulate");
+
+static unsigned int max_frequency_shift_hz;
+module_param(max_frequency_shift_hz, uint, 0);
+MODULE_PARM_DESC(max_frequency_shift_hz,
+ "Maximum shift in HZ allowed when tuning in a channel");
+
+DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nums);
+
+static int vidtv_start_streaming(struct vidtv_dvb *dvb)
+{
+ if (dvb->streaming) {
+ pr_warn_ratelimited("Already streaming. Skipping.\n");
+ return 0;
+ }
+
+ dvb->streaming = true;
+ return 0;
+}
+
+static int vidtv_stop_streaming(struct vidtv_dvb *dvb)
+{
+ dvb->streaming = false;
+
+ return 0;
+}
+
+static int vidtv_start_feed(struct dvb_demux_feed *feed)
+{
+ struct dvb_demux *demux = feed->demux;
+ struct vidtv_dvb *dvb = demux->priv;
+ int rc;
+ int ret;
+
+ if (!demux->dmx.frontend)
+ return -EINVAL;
+
+ mutex_lock(&dvb->feed_lock);
+
+ dvb->nfeeds++;
+ rc = dvb->nfeeds;
+
+ if (dvb->nfeeds == 1) {
+ ret = vidtv_start_streaming(dvb);
+ if (ret < 0)
+ rc = ret;
+ }
+
+ mutex_unlock(&dvb->feed_lock);
+ return rc;
+}
+
+static int vidtv_stop_feed(struct dvb_demux_feed *feed)
+{
+ struct dvb_demux *demux = feed->demux;
+ struct vidtv_dvb *dvb = demux->priv;
+ int err = 0;
+
+ mutex_lock(&dvb->feed_lock);
+ dvb->nfeeds--;
+
+ if (!dvb->nfeeds)
+ err = vidtv_stop_streaming(dvb);
+
+ mutex_unlock(&dvb->feed_lock);
+ return err;
+}
+
+static int vidtv_master_xfer(struct i2c_adapter *i2c_adap,
+ struct i2c_msg msgs[],
+ int num)
+{
+ return 0;
+}
+
+static u32 vidtv_i2c_func(struct i2c_adapter *adapter)
+{
+ return I2C_FUNC_I2C;
+}
+
+static struct i2c_algorithm vidtv_i2c_algorithm = {
+ .master_xfer = vidtv_master_xfer,
+ .functionality = vidtv_i2c_func,
+};
+
+static int vidtv_bridge_i2c_register_adap(struct vidtv_dvb *dvb)
+{
+ struct i2c_adapter *i2c_adapter = dvb->i2c_adapter;
+
+ strscpy(i2c_adapter->name, "vidtv_i2c", sizeof(i2c_adapter->name));
+ i2c_adapter->owner = THIS_MODULE;
+ i2c_adapter->algo = &vidtv_i2c_algorithm;
+ i2c_adapter->algo_data = NULL;
+ i2c_adapter->timeout = 500;
+ i2c_adapter->retries = 3;
+ i2c_adapter->dev.parent = NULL;
+
+ i2c_set_adapdata(i2c_adapter, dvb);
+ return i2c_add_adapter(dvb->i2c_adapter);
+}
+
+static int vidtv_bridge_register_adap(struct vidtv_dvb *dvb)
+{
+ int ret = 0;
+
+ ret = dvb_register_adapter(&dvb->adapter,
+ KBUILD_MODNAME,
+ THIS_MODULE,
+ &dvb->i2c_adapter->dev,
+ adapter_nums);
+
+ return ret;
+}
+
+static int vidtv_bridge_dmx_init(struct vidtv_dvb *dvb)
+{
+ dvb->demux.dmx.capabilities = DMX_TS_FILTERING |
+ DMX_SECTION_FILTERING;
+
+ dvb->demux.priv = dvb;
+ dvb->demux.filternum = 256;
+ dvb->demux.feednum = 256;
+ dvb->demux.start_feed = vidtv_start_feed;
+ dvb->demux.stop_feed = vidtv_stop_feed;
+
+ return dvb_dmx_init(&dvb->demux);
+}
+
+static int vidtv_bridge_dmxdev_init(struct vidtv_dvb *dvb)
+{
+ dvb->dmx_dev.filternum = 256;
+ dvb->dmx_dev.demux = &dvb->demux.dmx;
+ dvb->dmx_dev.capabilities = 0;
+
+ return dvb_dmxdev_init(&dvb->dmx_dev, &dvb->adapter);
+}
+
+static void vidtv_bridge_probe_demod(struct vidtv_dvb *dvb, u32 n)
+{
+ struct vidtv_demod_config cfg = {0};
+ struct dvb_frontend *fe = NULL;
+
+ cfg.frontend = &fe;
+ cfg.drop_tslock_prob_on_low_snr = drop_tslock_prob_on_low_snr;
+ cfg.recover_tslock_prob_on_good_snr = recover_tslock_prob_on_good_snr;
+
+ dvb->i2c_client_demod[n] = dvb_module_probe("vidtv_demod",
+ NULL,
+ dvb->i2c_adapter,
+ DEMOD_DEFAULT_ADDR,
+ &cfg);
+
+ /* retrieve a pointer to struct dvb_frontend */
+ dvb->fe[n] = *cfg.frontend;
+}
+
+static void vidtv_bridge_probe_tuner(struct vidtv_dvb *dvb, u32 n)
+{
+ struct vidtv_tuner_config cfg = {0};
+
+ cfg.fe = dvb->fe[n];
+ cfg.mock_power_up_delay_msec = mock_power_up_delay_msec;
+ cfg.mock_tune_delay_msec = mock_tune_delay_msec;
+
+ memcpy(cfg.vidtv_valid_dvb_t_freqs,
+ vidtv_valid_dvb_t_freqs,
+ sizeof(vidtv_valid_dvb_t_freqs));
+
+ memcpy(cfg.vidtv_valid_dvb_c_freqs,
+ vidtv_valid_dvb_c_freqs,
+ sizeof(vidtv_valid_dvb_c_freqs));
+
+ memcpy(cfg.vidtv_valid_dvb_s_freqs,
+ vidtv_valid_dvb_s_freqs,
+ sizeof(vidtv_valid_dvb_s_freqs));
+
+ cfg.max_frequency_shift_hz = max_frequency_shift_hz;
+
+ dvb->i2c_client_tuner[n] = dvb_module_probe("vidtv_tuner",
+ NULL,
+ dvb->i2c_adapter,
+ TUNER_DEFAULT_ADDR,
+ &cfg);
+}
+
+static int vidtv_bridge_dvb_init(struct vidtv_dvb *dvb)
+{
+ int ret;
+ int i;
+ int j;
+
+ ret = vidtv_bridge_i2c_register_adap(dvb);
+ if (ret < 0)
+ goto fail_i2c;
+
+ ret = vidtv_bridge_register_adap(dvb);
+ if (ret < 0)
+ goto fail_adapter;
+
+ vidtv_bridge_probe_demod(dvb, 0);
+ vidtv_bridge_probe_tuner(dvb, 0);
+
+ for (i = 0; i < NUM_FE; ++i) {
+ ret = dvb_register_frontend(&dvb->adapter, dvb->fe[i]);
+ if (ret < 0)
+ goto fail_fe;
+ }
+
+ ret = vidtv_bridge_dmx_init(dvb);
+ if (ret < 0)
+ goto fail_dmx;
+
+ ret = vidtv_bridge_dmxdev_init(dvb);
+ if (ret < 0)
+ goto fail_dmx_dev;
+
+ for (j = 0; j < NUM_FE; ++j) {
+ ret = dvb->demux.dmx.connect_frontend(&dvb->demux.dmx,
+ &dvb->dmx_fe[j]);
+ if (ret < 0)
+ goto fail_dmx_conn;
+
+ /*
+ * The source of the demux is a frontend connected
+ * to the demux.
+ */
+ dvb->dmx_fe[j].source = DMX_FRONTEND_0;
+ }
+
+ return ret;
+
+fail_dmx_conn:
+ for (j = j - 1; j >= 0; --j)
+ dvb->demux.dmx.remove_frontend(&dvb->demux.dmx,
+ &dvb->dmx_fe[j]);
+fail_dmx_dev:
+ dvb_dmxdev_release(&dvb->dmx_dev);
+fail_dmx:
+ dvb_dmx_release(&dvb->demux);
+fail_fe:
+ for (i = i - 1; i >= 0; --i)
+ dvb_unregister_frontend(dvb->fe[i]);
+
+fail_adapter:
+ dvb_unregister_adapter(&dvb->adapter);
+
+fail_i2c:
+ i2c_del_adapter(dvb->i2c_adapter);
+
+ return ret;
+}
+
+static int vidtv_bridge_i2c_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ int ret;
+ struct vidtv_dvb *dvb;
+
+ dvb = kzalloc(sizeof(*dvb), GFP_KERNEL);
+ if (!dvb)
+ return -ENOMEM;
+
+ ret = vidtv_bridge_dvb_init(dvb);
+ if (ret < 0)
+ goto err_dvb;
+
+ mutex_init(&dvb->feed_lock);
+
+ i2c_set_clientdata(client, dvb);
+
+ return ret;
+
+err_dvb:
+ kfree(dvb);
+ return ret;
+}
+
+static int vidtv_bridge_i2c_remove(struct i2c_client *client)
+{
+ struct vidtv_dvb *dvb;
+ u32 i;
+
+ dvb = i2c_get_clientdata(client);
+
+ mutex_destroy(&dvb->feed_lock);
+
+ for (i = 0; i < NUM_FE; ++i)
+ dvb->demux.dmx.remove_frontend(&dvb->demux.dmx,
+ &dvb->dmx_fe[i]);
+
+ dvb_dmxdev_release(&dvb->dmx_dev);
+ dvb_dmx_release(&dvb->demux);
+
+ for (i = 0; i < NUM_FE; ++i) {
+ dvb_unregister_frontend(dvb->fe[i]);
+ dvb_frontend_detach(dvb->fe[i]);
+ }
+
+ dvb_unregister_adapter(&dvb->adapter);
+
+ return 0;
+}
+
+static const struct i2c_device_id vidtv_bridge_id_table[] = {
+ {"vidtv_bridge", 0},
+ {}
+};
+
+MODULE_DEVICE_TABLE(i2c, vidtv_bridge_id_table);
+
+static struct i2c_driver vidtv_bridge_driver = {
+ .driver = {
+ .name = "vidtv_bridge",
+ .suppress_bind_attrs = true,
+ },
+ .probe = vidtv_bridge_i2c_probe,
+ .remove = vidtv_bridge_i2c_remove,
+ .id_table = vidtv_bridge_id_table,
+};
+
+module_i2c_driver(vidtv_bridge_driver);
diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridg.h b/drivers/media/test-drivers/vidtv/vidtv_bridg.h
new file mode 100644
index 0000000000000..dead155c2735c
--- /dev/null
+++ b/drivers/media/test-drivers/vidtv/vidtv_bridg.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * The Virtual DTV test driver serves as a reference DVB driver and helps
+ * validate the existing APIs in the media subsystem. It can also aid
+ * developers working on userspace applications.
+ *
+ * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
+ */
+
+#ifndef VIDTV_BRIDG_H
+#define VIDTV_BRIDG_H
+
+#define NUM_FE 1
+
+#include <linux/types.h>
+#include <media/dvb_frontend.h>
+#include <media/dvb_demux.h>
+#include <media/dmxdev.h>
+#include <linux/i2c.h>
+
+struct vidtv_dvb {
+ struct dvb_frontend *fe[NUM_FE];
+ struct dvb_adapter adapter;
+ struct dvb_demux demux;
+ struct dmxdev dmx_dev;
+ struct dmx_frontend dmx_fe[NUM_FE];
+ struct i2c_adapter *i2c_adapter;
+ struct i2c_client *i2c_client_demod[NUM_FE];
+ struct i2c_client *i2c_client_tuner[NUM_FE];
+
+ u32 nfeeds;
+ struct mutex feed_lock; /* start/stop feed */
+
+ bool streaming;
+};
+
+#endif // VIDTV_BRIDG_H
--
2.26.2