Generic serial MIDI driver adding support for using serial devices compatible with the serial bus as raw MIDI devices, allowing using additional serial devices not compatible with the existing serial-u16550 driver. Supports only setting standard serial baudrates on the underlying serial device; however, the underlying serial device can be configured so that a requested 38.4 kBaud is actually the standard MIDI 31.25 kBaud. Supports DeviceTree configuration.
Signed-off-by: Daniel Kaehn kaehndan@gmail.com --- sound/drivers/Kconfig | 18 ++ sound/drivers/Makefile | 2 + sound/drivers/serial-generic.c | 377 +++++++++++++++++++++++++++++++++ 3 files changed, 397 insertions(+) create mode 100644 sound/drivers/serial-generic.c
diff --git a/sound/drivers/Kconfig b/sound/drivers/Kconfig index ca4cdf666f82..060e7d3f2439 100644 --- a/sound/drivers/Kconfig +++ b/sound/drivers/Kconfig @@ -165,6 +165,24 @@ config SND_SERIAL_U16550 To compile this driver as a module, choose M here: the module will be called snd-serial-u16550.
+config SND_SERIAL_GENERIC + tristate "Generic serial MIDI driver" + depends on SERIAL_DEV_BUS + depends on OF + select SND_RAWMIDI + help + To include support for mapping generic serial devices as raw + ALSA MIDI devices, say Y here. The driver only supports setting + the serial port to standard baudrates. To attain the standard MIDI + baudrate of 31.25 kBaud, configure the clock of the underlying serial + device so that a requested 38.4 kBaud will result in the standard speed. + + Use this devicetree binding to configure serial port mapping + file:Documentation/devicetree/bindings/sound/serialmidi.yaml + + To compile this driver as a module, choose M here: the module + will be called snd-serial-generic. + config SND_MPU401 tristate "Generic MPU-401 UART driver" select SND_MPU401_UART diff --git a/sound/drivers/Makefile b/sound/drivers/Makefile index c0fe4eccdaef..b60303180a1b 100644 --- a/sound/drivers/Makefile +++ b/sound/drivers/Makefile @@ -10,6 +10,7 @@ snd-mtpav-objs := mtpav.o snd-mts64-objs := mts64.o snd-portman2x4-objs := portman2x4.o snd-serial-u16550-objs := serial-u16550.o +snd-serial-generic-objs := serial-generic.o snd-virmidi-objs := virmidi.o
# Toplevel Module Dependency @@ -17,6 +18,7 @@ obj-$(CONFIG_SND_DUMMY) += snd-dummy.o obj-$(CONFIG_SND_ALOOP) += snd-aloop.o obj-$(CONFIG_SND_VIRMIDI) += snd-virmidi.o obj-$(CONFIG_SND_SERIAL_U16550) += snd-serial-u16550.o +obj-$(CONFIG_SND_SERIAL_GENERIC) += snd-serial-generic.o obj-$(CONFIG_SND_MTPAV) += snd-mtpav.o obj-$(CONFIG_SND_MTS64) += snd-mts64.o obj-$(CONFIG_SND_PORTMAN2X4) += snd-portman2x4.o diff --git a/sound/drivers/serial-generic.c b/sound/drivers/serial-generic.c new file mode 100644 index 000000000000..8168f8a71e15 --- /dev/null +++ b/sound/drivers/serial-generic.c @@ -0,0 +1,377 @@ +// 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_device.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)) { + 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 int snd_serial_generic_receive_buf(struct serdev_device *serdev, + const unsigned char *buf, size_t count) +{ + int ret; + struct snd_serial_generic *drvdata = serdev_device_get_drvdata(serdev); + + 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) { + dev_dbg(drvdata->card->dev, "DEBUG - Opening serial port for card %s\n", + drvdata->card->shortname); + err = serdev_device_open(drvdata->serdev); + if (err < 0) + return err; + if (drvdata->baudrate) { + 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, "DEBUG - 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; + + clear_bit(SERIAL_MODE_INPUT_OPEN, &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, "DEBUG - 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, "DEBUG - output close called\n"); + clear_bit(SERIAL_MODE_INPUT_OPEN, &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; + + dev_dbg(drvdata->card->dev, "DEBUG - Output trigger called with %d\n", up); + + 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; + + dev_dbg(drvdata->card->dev, "DEBUG - output drain called\n"); + + /* 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; + + if (serdev->dev.of_node) { + err = of_property_read_u32(serdev->dev.of_node, "current-speed", + &drvdata->baudrate); + if (err < 0) { + dev_warn(drvdata->card->dev, + "MIDI device reading of current-speed DT param failed with error %d, using default baudrate of serial device\n", + err); + drvdata->baudrate = 0; + } + } else { + dev_info(drvdata->card->dev, "MIDI device current-speed DT param not set for %s, using default baudrate of serial device\n", + drvdata->card->shortname); + drvdata->baudrate = 0; + } +} + +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; + + err = snd_card_register(card); + if (err < 0) + return err; + + serdev_device_set_client_ops(serdev, &snd_serial_generic_serdev_device_ops); + serdev_device_set_drvdata(drvdata->serdev, drvdata); + + return 0; +} + +#define SND_SERIAL_GENERIC_DRIVER "snd-serial-generic" + +static const struct of_device_id snd_serial_generic_dt_ids[] = { + { .compatible = "serialmidi" }, + {}, +}; + +MODULE_DEVICE_TABLE(of, snd_serial_generic_dt_ids); + +static struct serdev_device_driver snd_serial_generic_driver = { + .driver = { + .name = SND_SERIAL_GENERIC_DRIVER, + .of_match_table = of_match_ptr(snd_serial_generic_dt_ids), + }, + .probe = snd_serial_generic_probe, +}; + +module_serdev_device_driver(snd_serial_generic_driver);