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linux/sound/drivers/serial-generic.c
Francesco Dolcini fed99212ac treewide, serdev: change receive_buf() return type to size_t 
receive_buf() is called from ttyport_receive_buf() that expects values
">= 0" from serdev_controller_receive_buf(), change its return type from
ssize_t to size_t.

The need for this clean-up was noticed while fixing a warning, see
commit 94d0539425 ("Bluetooth: btnxpuart: fix recv_buf() return value").
Changing the callback prototype to return an unsigned seems the best way
to document the API and ensure that is properly used.

GNSS drivers implementation of serdev receive_buf() callback return
directly the return value of gnss_insert_raw(). gnss_insert_raw()
returns a signed int, however this is not an issue since the value
returned is always positive, because of the kfifo_in() implementation.
gnss_insert_raw() could be changed to return also an unsigned, however
this is not implemented here as request by the GNSS maintainer Johan
Hovold.

Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/all/087be419-ec6b-47ad-851a-5e1e3ea5cfcc@kernel.org/
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> #for-iio
Reviewed-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Acked-by: Maximilian Luz <luzmaximilian@gmail.com>  # for platform/surface
Acked-by: Lee Jones <lee@kernel.org>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20240122180551.34429-1-francesco@dolcini.it
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-01-27 18:13:53 -08:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* serial-generic.c
* Copyright (c) by Daniel Kaehn <kaehndan@gmail.com
* Based on serial-u16550.c by Jaroslav Kysela <perex@perex.cz>,
* Isaku Yamahata <yamahata@private.email.ne.jp>,
* George Hansper <ghansper@apana.org.au>,
* Hannu Savolainen
*
* Generic serial MIDI driver using the serdev serial bus API for hardware interaction
*/
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/serdev.h>
#include <linux/serial_reg.h>
#include <linux/slab.h>
#include <linux/dev_printk.h>
#include <sound/core.h>
#include <sound/rawmidi.h>
#include <sound/initval.h>
MODULE_DESCRIPTION("Generic serial MIDI driver");
MODULE_LICENSE("GPL");
#define SERIAL_MODE_INPUT_OPEN 1
#define SERIAL_MODE_OUTPUT_OPEN 2
#define SERIAL_MODE_INPUT_TRIGGERED 3
#define SERIAL_MODE_OUTPUT_TRIGGERED 4
#define SERIAL_TX_STATE_ACTIVE 1
#define SERIAL_TX_STATE_WAKEUP 2
struct snd_serial_generic {
struct serdev_device *serdev;
struct snd_card *card;
struct snd_rawmidi *rmidi;
struct snd_rawmidi_substream *midi_output;
struct snd_rawmidi_substream *midi_input;
unsigned int baudrate;
unsigned long filemode; /* open status of file */
struct work_struct tx_work;
unsigned long tx_state;
};
static void snd_serial_generic_tx_wakeup(struct snd_serial_generic *drvdata)
{
if (test_and_set_bit(SERIAL_TX_STATE_ACTIVE, &drvdata->tx_state))
set_bit(SERIAL_TX_STATE_WAKEUP, &drvdata->tx_state);
schedule_work(&drvdata->tx_work);
}
#define INTERNAL_BUF_SIZE 256
static void snd_serial_generic_tx_work(struct work_struct *work)
{
static char buf[INTERNAL_BUF_SIZE];
int num_bytes;
struct snd_serial_generic *drvdata = container_of(work, struct snd_serial_generic,
tx_work);
struct snd_rawmidi_substream *substream = drvdata->midi_output;
clear_bit(SERIAL_TX_STATE_WAKEUP, &drvdata->tx_state);
while (!snd_rawmidi_transmit_empty(substream)) {
if (!test_bit(SERIAL_MODE_OUTPUT_OPEN, &drvdata->filemode))
break;
num_bytes = snd_rawmidi_transmit_peek(substream, buf, INTERNAL_BUF_SIZE);
num_bytes = serdev_device_write_buf(drvdata->serdev, buf, num_bytes);
if (!num_bytes)
break;
snd_rawmidi_transmit_ack(substream, num_bytes);
if (!test_bit(SERIAL_TX_STATE_WAKEUP, &drvdata->tx_state))
break;
}
clear_bit(SERIAL_TX_STATE_ACTIVE, &drvdata->tx_state);
}
static void snd_serial_generic_write_wakeup(struct serdev_device *serdev)
{
struct snd_serial_generic *drvdata = serdev_device_get_drvdata(serdev);
snd_serial_generic_tx_wakeup(drvdata);
}
static size_t snd_serial_generic_receive_buf(struct serdev_device *serdev,
const u8 *buf, size_t count)
{
int ret;
struct snd_serial_generic *drvdata = serdev_device_get_drvdata(serdev);
if (!test_bit(SERIAL_MODE_INPUT_OPEN, &drvdata->filemode))
return 0;
ret = snd_rawmidi_receive(drvdata->midi_input, buf, count);
return ret < 0 ? 0 : ret;
}
static const struct serdev_device_ops snd_serial_generic_serdev_device_ops = {
.receive_buf = snd_serial_generic_receive_buf,
.write_wakeup = snd_serial_generic_write_wakeup
};
static int snd_serial_generic_ensure_serdev_open(struct snd_serial_generic *drvdata)
{
int err;
unsigned int actual_baud;
if (drvdata->filemode)
return 0;
dev_dbg(drvdata->card->dev, "Opening serial port for card %s\n",
drvdata->card->shortname);
err = serdev_device_open(drvdata->serdev);
if (err < 0)
return err;
actual_baud = serdev_device_set_baudrate(drvdata->serdev,
drvdata->baudrate);
if (actual_baud != drvdata->baudrate) {
dev_warn(drvdata->card->dev, "requested %d baud for card %s but it was actually set to %d\n",
drvdata->baudrate, drvdata->card->shortname, actual_baud);
}
return 0;
}
static int snd_serial_generic_input_open(struct snd_rawmidi_substream *substream)
{
int err;
struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
dev_dbg(drvdata->card->dev, "Opening input for card %s\n",
drvdata->card->shortname);
err = snd_serial_generic_ensure_serdev_open(drvdata);
if (err < 0)
return err;
set_bit(SERIAL_MODE_INPUT_OPEN, &drvdata->filemode);
drvdata->midi_input = substream;
return 0;
}
static int snd_serial_generic_input_close(struct snd_rawmidi_substream *substream)
{
struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
dev_dbg(drvdata->card->dev, "Closing input for card %s\n",
drvdata->card->shortname);
clear_bit(SERIAL_MODE_INPUT_OPEN, &drvdata->filemode);
clear_bit(SERIAL_MODE_INPUT_TRIGGERED, &drvdata->filemode);
drvdata->midi_input = NULL;
if (!drvdata->filemode)
serdev_device_close(drvdata->serdev);
return 0;
}
static void snd_serial_generic_input_trigger(struct snd_rawmidi_substream *substream,
int up)
{
struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
if (up)
set_bit(SERIAL_MODE_INPUT_TRIGGERED, &drvdata->filemode);
else
clear_bit(SERIAL_MODE_INPUT_TRIGGERED, &drvdata->filemode);
}
static int snd_serial_generic_output_open(struct snd_rawmidi_substream *substream)
{
struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
int err;
dev_dbg(drvdata->card->dev, "Opening output for card %s\n",
drvdata->card->shortname);
err = snd_serial_generic_ensure_serdev_open(drvdata);
if (err < 0)
return err;
set_bit(SERIAL_MODE_OUTPUT_OPEN, &drvdata->filemode);
drvdata->midi_output = substream;
return 0;
};
static int snd_serial_generic_output_close(struct snd_rawmidi_substream *substream)
{
struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
dev_dbg(drvdata->card->dev, "Closing output for card %s\n",
drvdata->card->shortname);
clear_bit(SERIAL_MODE_OUTPUT_OPEN, &drvdata->filemode);
clear_bit(SERIAL_MODE_OUTPUT_TRIGGERED, &drvdata->filemode);
if (!drvdata->filemode)
serdev_device_close(drvdata->serdev);
drvdata->midi_output = NULL;
return 0;
};
static void snd_serial_generic_output_trigger(struct snd_rawmidi_substream *substream,
int up)
{
struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
if (up)
set_bit(SERIAL_MODE_OUTPUT_TRIGGERED, &drvdata->filemode);
else
clear_bit(SERIAL_MODE_OUTPUT_TRIGGERED, &drvdata->filemode);
if (up)
snd_serial_generic_tx_wakeup(drvdata);
}
static void snd_serial_generic_output_drain(struct snd_rawmidi_substream *substream)
{
struct snd_serial_generic *drvdata = substream->rmidi->card->private_data;
/* Flush any pending characters */
serdev_device_write_flush(drvdata->serdev);
cancel_work_sync(&drvdata->tx_work);
}
static const struct snd_rawmidi_ops snd_serial_generic_output = {
.open = snd_serial_generic_output_open,
.close = snd_serial_generic_output_close,
.trigger = snd_serial_generic_output_trigger,
.drain = snd_serial_generic_output_drain,
};
static const struct snd_rawmidi_ops snd_serial_generic_input = {
.open = snd_serial_generic_input_open,
.close = snd_serial_generic_input_close,
.trigger = snd_serial_generic_input_trigger,
};
static void snd_serial_generic_parse_dt(struct serdev_device *serdev,
struct snd_serial_generic *drvdata)
{
int err;
err = of_property_read_u32(serdev->dev.of_node, "current-speed",
&drvdata->baudrate);
if (err < 0) {
dev_dbg(drvdata->card->dev,
"MIDI device reading of current-speed DT param failed with error %d, using default of 38400\n",
err);
drvdata->baudrate = 38400;
}
}
static void snd_serial_generic_substreams(struct snd_rawmidi_str *stream, int dev_num)
{
struct snd_rawmidi_substream *substream;
list_for_each_entry(substream, &stream->substreams, list) {
sprintf(substream->name, "Serial MIDI %d-%d", dev_num, substream->number);
}
}
static int snd_serial_generic_rmidi(struct snd_serial_generic *drvdata,
int outs, int ins, struct snd_rawmidi **rmidi)
{
struct snd_rawmidi *rrawmidi;
int err;
err = snd_rawmidi_new(drvdata->card, drvdata->card->driver, 0,
outs, ins, &rrawmidi);
if (err < 0)
return err;
snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_INPUT,
&snd_serial_generic_input);
snd_rawmidi_set_ops(rrawmidi, SNDRV_RAWMIDI_STREAM_OUTPUT,
&snd_serial_generic_output);
strcpy(rrawmidi->name, drvdata->card->shortname);
snd_serial_generic_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT],
drvdata->serdev->ctrl->nr);
snd_serial_generic_substreams(&rrawmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT],
drvdata->serdev->ctrl->nr);
rrawmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
SNDRV_RAWMIDI_INFO_INPUT |
SNDRV_RAWMIDI_INFO_DUPLEX;
if (rmidi)
*rmidi = rrawmidi;
return 0;
}
static int snd_serial_generic_probe(struct serdev_device *serdev)
{
struct snd_card *card;
struct snd_serial_generic *drvdata;
int err;
err = snd_devm_card_new(&serdev->dev, SNDRV_DEFAULT_IDX1,
SNDRV_DEFAULT_STR1, THIS_MODULE,
sizeof(struct snd_serial_generic), &card);
if (err < 0)
return err;
strcpy(card->driver, "SerialMIDI");
sprintf(card->shortname, "SerialMIDI-%d", serdev->ctrl->nr);
sprintf(card->longname, "Serial MIDI device at serial%d", serdev->ctrl->nr);
drvdata = card->private_data;
drvdata->serdev = serdev;
drvdata->card = card;
snd_serial_generic_parse_dt(serdev, drvdata);
INIT_WORK(&drvdata->tx_work, snd_serial_generic_tx_work);
err = snd_serial_generic_rmidi(drvdata, 1, 1, &drvdata->rmidi);
if (err < 0)
return err;
serdev_device_set_client_ops(serdev, &snd_serial_generic_serdev_device_ops);
serdev_device_set_drvdata(drvdata->serdev, drvdata);
err = snd_card_register(card);
if (err < 0)
return err;
return 0;
}
static const struct of_device_id snd_serial_generic_dt_ids[] = {
{ .compatible = "serial-midi" },
{},
};
MODULE_DEVICE_TABLE(of, snd_serial_generic_dt_ids);
static struct serdev_device_driver snd_serial_generic_driver = {
.driver = {
.name = "snd-serial-generic",
.of_match_table = snd_serial_generic_dt_ids,
},
.probe = snd_serial_generic_probe,
};
module_serdev_device_driver(snd_serial_generic_driver);
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