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SubjectRe: [RFC, WIP, v6 02/10] media: vidtv: implement a tuner driver
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On 5/20/20 1:03 AM, Daniel W. S. Almeida wrote:
> From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>

Are you using git send-email to send patches. Why do have this
From line in here? Same comment on all other patches in this series.

>
> The virtual DVB 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.
>
> This dummy tuner should support common TV standards such as DVB-T/T2/S/S2,
> ISDB-T and ATSC when completed.
>
> Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> ---
> drivers/media/test-drivers/vidtv/Makefile | 3 +
> .../media/test-drivers/vidtv/vidtv_tuner.c | 408 ++++++++++++++++++
> .../media/test-drivers/vidtv/vidtv_tuner.h | 26 ++
> 3 files changed, 437 insertions(+)
> create mode 100644 drivers/media/test-drivers/vidtv/vidtv_tuner.c
> create mode 100644 drivers/media/test-drivers/vidtv/vidtv_tuner.h
>
> diff --git a/drivers/media/test-drivers/vidtv/Makefile b/drivers/media/test-drivers/vidtv/Makefile
> index d1558d84eeaed..58e022c094e5e 100644
> --- a/drivers/media/test-drivers/vidtv/Makefile
> +++ b/drivers/media/test-drivers/vidtv/Makefile
> @@ -1,2 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0
>
> +dvb-vidtv-tuner-objs := vidtv_tuner.o
> +
> +obj-$(CONFIG_DVB_VIDTV) += dvb-vidtv-tuner.o
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_tuner.c b/drivers/media/test-drivers/vidtv/vidtv_tuner.c
> new file mode 100644
> index 0000000000000..3f2b4b9a6d568
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_tuner.c
> @@ -0,0 +1,408 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * The Virtual DVB 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.
> + *
> + * The vidtv tuner should support common TV standards such as
> + * DVB-T/T2/S/S2, ISDB-T and ATSC when completed.
> + *
> + * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>

Use Copyright (C) 2020 Daniel W. S. Almeida <dwlsalmeida@gmail.com>

Check other drivers for reference. Do the same in all other files
in this series.

> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
> +
> +#include <linux/errno.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <media/dvb_frontend.h>
> +#include <linux/printk.h>
> +#include <linux/ratelimit.h>
> +
> +#include "vidtv_tuner.h"
> +
> +MODULE_DESCRIPTION("Virtual DVB Tuner");
> +MODULE_AUTHOR("Daniel W. S. Almeida");
> +MODULE_LICENSE("GPL");
> +
> +struct vidtv_tuner_cnr_to_qual_s {
> + /* attempt to use the same values as libdvbv5 */
> + u32 modulation;
> + u32 fec;
> + u32 cnr_ok, cnr_good;

Add cnr_good on a separate line.
u32 cnr_good;
> +};

Add a comment for each of these fields describing
what they are for.

> +
> +static const struct vidtv_tuner_cnr_to_qual_s vidtv_tuner_c_cnr_2_qual[] = {
> + /* from libdvbv5 source code, in milli db */
> + { QAM_256, FEC_NONE, 34000, 38000},
> + { QAM_64, FEC_NONE, 30000, 34000},
> +};
> +
> +static const struct vidtv_tuner_cnr_to_qual_s vidtv_tuner_s_cnr_2_qual[] = {
> + /* from libdvbv5 source code, in milli db */
> + { QPSK, FEC_1_2, 7000, 10000},
> +

Any reason for this blank line here?

> + { QPSK, FEC_2_3, 9000, 12000},
> + { QPSK, FEC_3_4, 10000, 13000},
> + { QPSK, FEC_5_6, 11000, 14000},
> +

Any reason for this blank line here?

> + { QPSK, FEC_7_8, 12000, 15000},
> +};
> +
> +static const struct vidtv_tuner_cnr_to_qual_s vidtv_tuner_s2_cnr_2_qual[] = {
> + /* from libdvbv5 source code, in milli db */
> + { QPSK, FEC_1_2, 9000, 12000},
> + { QPSK, FEC_2_3, 11000, 14000},
> + { QPSK, FEC_3_4, 12000, 15000},
> + { QPSK, FEC_5_6, 12000, 15000},
> + { QPSK, FEC_8_9, 13000, 16000},
> + { QPSK, FEC_9_10, 13500, 16500},
> + { PSK_8, FEC_2_3, 14500, 17500},
> + { PSK_8, FEC_3_4, 16000, 19000},
> + { PSK_8, FEC_5_6, 17500, 20500},
> + { PSK_8, FEC_8_9, 19000, 22000},
> +};
> +
> +static const struct vidtv_tuner_cnr_to_qual_s vidtv_tuner_t_cnr_2_qual[] = {
> + /* from libdvbv5 source code, in milli db*/
> + { QPSK, FEC_1_2, 4100, 5900},
> + { QPSK, FEC_2_3, 6100, 9600},
> + { QPSK, FEC_3_4, 7200, 12400},
> + { QPSK, FEC_5_6, 8500, 15600},
> + { QPSK, FEC_7_8, 9200, 17500},
> +
> + { QAM_16, FEC_1_2, 9800, 11800},
> + { QAM_16, FEC_2_3, 12100, 15300},
> + { QAM_16, FEC_3_4, 13400, 18100},
> + { QAM_16, FEC_5_6, 14800, 21300},
> + { QAM_16, FEC_7_8, 15700, 23600},
> +
> + { QAM_64, FEC_1_2, 14000, 16000},
> + { QAM_64, FEC_2_3, 19900, 25400},
> + { QAM_64, FEC_3_4, 24900, 27900},
> + { QAM_64, FEC_5_6, 21300, 23300},
> + { QAM_64, FEC_7_8, 22000, 24000},
> +};
> +
> +struct vidtv_tuner_hardware_state {
> + bool asleep;
> + u32 lock_status;
> + u32 if_frequency;
> + u32 tuned_frequency;
> + u32 bandwidth;
> +};
> +

Add a comment for each of these fields describing
what they are for.

> +struct vidtv_tuner_dev {
> + struct dvb_frontend *fe;
> + struct vidtv_tuner_hardware_state hw_state;
> + struct vidtv_tuner_config config;
> +};
> +

Add a comment for each of these fields describing
what they are for.

> +static struct vidtv_tuner_dev*
> +vidtv_tuner_get_dev(struct dvb_frontend *fe)
> +{
> + struct i2c_client *client = fe->tuner_priv;
> +
> + return i2c_get_clientdata(client);

Why not simplfy this to just return i2c_get_clientdata(fe->tuner_priv)
Safer to check if tuner_priv is valid.

> +}
> +
> +static s32 vidtv_tuner_check_frequency_shift(struct dvb_frontend *fe)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> + struct dtv_frontend_properties *c = &fe->dtv_property_cache;
> + struct vidtv_tuner_config config = tuner_dev->config;
> + u32 *valid_freqs = NULL;
> + u32 array_sz = 0;
> + u32 i;
> + u32 shift;

Align i and shift with the rest of the variables.

> +
> + switch (c->delivery_system) {

Add indetation for the below:

> + case SYS_DVBT:
> + case SYS_DVBT2:
> + valid_freqs = config.vidtv_valid_dvb_t_freqs;
> + array_sz = ARRAY_SIZE(config.vidtv_valid_dvb_t_freqs);
> + break;
> + case SYS_DVBS:
> + case SYS_DVBS2:
> + valid_freqs = config.vidtv_valid_dvb_s_freqs;
> + array_sz = ARRAY_SIZE(config.vidtv_valid_dvb_s_freqs);
> + break;
> + case SYS_DVBC_ANNEX_A:
> + valid_freqs = config.vidtv_valid_dvb_c_freqs;
> + array_sz = ARRAY_SIZE(config.vidtv_valid_dvb_c_freqs);
> + break;
> +
> + default:
> + pr_warn("%s: unsupported delivery system: %u\n",
> + __func__,
> + c->delivery_system);
> +
> + return -EINVAL;
> + }
> +
> + for (i = 0; i < array_sz; i++) {
> + shift = abs(c->frequency - valid_freqs[i]);
> +
> + if (!shift)
> + return 0;
> +
> + /*
> + * This will provide a value from 0 to 100 that would
> + * indicate how far is the tuned frequency from the
> + * right one.
> + */
> + if (shift < config.max_frequency_shift_hz)
> + return shift * 100 / config.max_frequency_shift_hz;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int
> +vidtv_tuner_get_signal_strength(struct dvb_frontend *fe, u16 *strength)
> +{
> + struct dtv_frontend_properties *c = &fe->dtv_property_cache;

Why do you need white spaces between *c and assignment?

> + const struct vidtv_tuner_cnr_to_qual_s *cnr2qual = NULL;
> + u32 array_size = 0;

Same here. Don't align them when it doesn't make sense. This makes
it not readable.

> + s32 shift;
> + u32 i;
> +
> + shift = vidtv_tuner_check_frequency_shift(fe);
> +
> + switch (c->delivery_system) {

Ident.

> + case SYS_DVBT:
> + case SYS_DVBT2:
> + cnr2qual = vidtv_tuner_t_cnr_2_qual;
> + array_size = ARRAY_SIZE(vidtv_tuner_t_cnr_2_qual);
> + break;
> +
> + case SYS_DVBS:
> + cnr2qual = vidtv_tuner_s_cnr_2_qual;
> + array_size = ARRAY_SIZE(vidtv_tuner_s_cnr_2_qual);
> + break;
> +
> + case SYS_DVBS2:
> + cnr2qual = vidtv_tuner_s2_cnr_2_qual;
> + array_size = ARRAY_SIZE(vidtv_tuner_s2_cnr_2_qual);
> + break;
> +
> + case SYS_DVBC_ANNEX_A:
> + cnr2qual = vidtv_tuner_c_cnr_2_qual;
> + array_size = ARRAY_SIZE(vidtv_tuner_c_cnr_2_qual);
> + break;
> +
> + default:
> + pr_warn_ratelimited("%s: unsupported delivery system: %u\n",
> + __func__,
> + c->delivery_system);
> + return -EINVAL;
> + }
> +
> + for (i = 0; i <= array_size; i++) {
> + if (cnr2qual[i].modulation != c->modulation ||
> + cnr2qual[i].fec != c->fec_inner)
> + continue;
> +
> + if (!shift) {
> + *strength = cnr2qual[i].cnr_good;
> + return 0;
> + }
> + if (shift < 0) { /* Channel not tuned */
> + *strength = 0;
> + return 0;
> + }
> + /*
> + * Channel tuned at wrong frequency. Simulate that the
> + * Carrier S/N ratio is not too good.
> + */
> +
> + *strength = cnr2qual[i].cnr_ok -
> + (cnr2qual[i].cnr_good - cnr2qual[i].cnr_ok);
> + return 0;
> + }
> +
> + /*
> + * do a linear interpolation between 34dB and 10dB if we can't
> + * match against the table
> + */
> + *strength = 34 - 24 * shift / 100;
> + return 0;
> +}
> +
> +static int vidtv_tuner_init(struct dvb_frontend *fe)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> + struct vidtv_tuner_config config = tuner_dev->config;
> +
> + msleep_interruptible(config.mock_power_up_delay_msec);
> +
> + tuner_dev->hw_state.asleep = false;
> + tuner_dev->hw_state.if_frequency = 5000;

There is no need to align these.

> +
> + return 0;
> +}
> +
> +static int vidtv_tuner_sleep(struct dvb_frontend *fe)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + tuner_dev->hw_state.asleep = true;
> + return 0;
> +}
> +
> +static int vidtv_tuner_suspend(struct dvb_frontend *fe)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + tuner_dev->hw_state.asleep = true;
> + return 0;
> +}
> +
> +static int vidtv_tuner_resume(struct dvb_frontend *fe)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + tuner_dev->hw_state.asleep = false;
> + return 0;
> +}
> +
> +static int vidtv_tuner_set_params(struct dvb_frontend *fe)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> + struct vidtv_tuner_config config = tuner_dev->config;
> + struct dtv_frontend_properties *c = &fe->dtv_property_cache;

Add a blank line and don't try to align these. Looks very odd.

> + u32 min_freq = fe->ops.tuner_ops.info.frequency_min_hz;
> + u32 max_freq = fe->ops.tuner_ops.info.frequency_max_hz;
> + u32 min_bw = fe->ops.tuner_ops.info.bandwidth_min;
> + u32 max_bw = fe->ops.tuner_ops.info.bandwidth_max;
> +
> + if (c->frequency < min_freq || c->frequency > max_freq ||
> + c->bandwidth_hz < min_bw || c->bandwidth_hz > max_bw) {
> + tuner_dev->hw_state.lock_status = 0;
> + return -EINVAL;
> + }
> +
> + tuner_dev->hw_state.tuned_frequency = c->frequency;
> + tuner_dev->hw_state.bandwidth = c->bandwidth_hz;
> + tuner_dev->hw_state.lock_status = TUNER_STATUS_LOCKED;
> +
> + msleep_interruptible(config.mock_tune_delay_msec);
> + return 0;
> +}
> +
> +static int vidtv_tuner_set_config(struct dvb_frontend *fe,
> + void *priv_cfg)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + memcpy(&tuner_dev->config, priv_cfg, sizeof(tuner_dev->config));
> +
> + return 0;
> +}
> +
> +static int vidtv_tuner_get_frequency(struct dvb_frontend *fe,
> + u32 *frequency)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + *frequency = tuner_dev->hw_state.tuned_frequency;
> +
> + return 0;
> +}
> +
> +static int vidtv_tuner_get_bandwidth(struct dvb_frontend *fe,
> + u32 *bandwidth)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + *bandwidth = tuner_dev->hw_state.bandwidth;
> +
> + return 0;
> +}
> +
> +static int vidtv_tuner_get_if_frequency(struct dvb_frontend *fe,
> + u32 *frequency)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + *frequency = tuner_dev->hw_state.if_frequency;
> +
> + return 0;
> +}
> +
> +static int vidtv_tuner_get_status(struct dvb_frontend *fe, u32 *status)
> +{
> + struct vidtv_tuner_dev *tuner_dev = vidtv_tuner_get_dev(fe);
> +
> + *status = tuner_dev->hw_state.lock_status;
> +
> + return 0;
> +}
> +
> +static const struct dvb_tuner_ops vidtv_tuner_ops = {
> + .init = vidtv_tuner_init,
> + .sleep = vidtv_tuner_sleep,
> + .suspend = vidtv_tuner_suspend,
> + .resume = vidtv_tuner_resume,
> + .set_params = vidtv_tuner_set_params,
> + .set_config = vidtv_tuner_set_config,
> + .get_bandwidth = vidtv_tuner_get_bandwidth,
> + .get_frequency = vidtv_tuner_get_frequency,
> + .get_if_frequency = vidtv_tuner_get_if_frequency,
> + .get_status = vidtv_tuner_get_status,
> + .get_rf_strength = vidtv_tuner_get_signal_strength
> +};
> +
> +static const struct i2c_device_id vidtv_tuner_i2c_id_table[] = {
> + {"vidtv_tuner", 0},
> + {}
> +};
> +MODULE_DEVICE_TABLE(i2c, vidtv_tuner_i2c_id_table);
> +
> +static int vidtv_tuner_i2c_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct vidtv_tuner_config *config = client->dev.platform_data;
> + struct dvb_frontend *fe = config->fe;
> + struct vidtv_tuner_dev *tuner_dev = NULL;
> +
> + tuner_dev = kzalloc(sizeof(*tuner_dev), GFP_KERNEL);
> + if (!tuner_dev)
> + return -ENOMEM;
> +
> + tuner_dev->fe = config->fe;
> + i2c_set_clientdata(client, tuner_dev);
> +
> + memcpy(&fe->ops.tuner_ops,
> + &vidtv_tuner_ops,
> + sizeof(struct dvb_tuner_ops));
> +
> + fe->tuner_priv = client;
> +
> + return 0;
> +}
> +
> +static int vidtv_tuner_i2c_remove(struct i2c_client *client)
> +{
> + struct vidtv_tuner_dev *tuner_dev = i2c_get_clientdata(client);
> + struct dvb_frontend *fe = tuner_dev->fe;
> +
> + memset(&fe->ops.tuner_ops, 0, sizeof(struct dvb_tuner_ops));
> + fe->tuner_priv = NULL;
> + kfree(tuner_dev);
> +
> + return 0;
> +}
> +
> +static struct i2c_driver vidtv_tuner_i2c_driver = {
> + .driver = {
> + .name = "vidtv_tuner",
> + .suppress_bind_attrs = true,
> + },
> + .probe = vidtv_tuner_i2c_probe,
> + .remove = vidtv_tuner_i2c_remove,
> + .id_table = vidtv_tuner_i2c_id_table,
> +};
> +module_i2c_driver(vidtv_tuner_i2c_driver);
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_tuner.h b/drivers/media/test-drivers/vidtv/vidtv_tuner.h
> new file mode 100644
> index 0000000000000..46407739f5d44
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_tuner.h
> @@ -0,0 +1,26 @@
> +/* 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_TUNER_H
> +#define VIDTV_TUNER_H
> +
> +#include <linux/types.h>
> +#include <media/dvb_frontend.h>
> +
> +struct vidtv_tuner_config {
> + struct dvb_frontend *fe;
> + u32 mock_power_up_delay_msec;
> + u32 mock_tune_delay_msec;
> + u32 vidtv_valid_dvb_t_freqs[8];
> + u32 vidtv_valid_dvb_c_freqs[8];
> + u32 vidtv_valid_dvb_s_freqs[8];

Don't hrd code these. Add defines for them.

> + u8 max_frequency_shift_hz;
> +};
> +
> +#endif //VIDTV_TUNER_H
>

thanks,
-- Shuah

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