ata: pata_parport: add driver (PARIDE replacement)

The pata_parport is a libata-based replacement of the old PARIDE
subsystem - driver for parallel port IDE devices.
It uses the original paride low-level protocol drivers but does not
need the high-level drivers (pd, pcd, pf, pt, pg). The IDE devices
behind parallel port adapters are handled by the ATA layer.

This will allow paride and its high-level drivers to be removed.

Unfortunately, libata drivers cannot sleep so pata_parport claims
parport before activating the ata host and keeps it claimed (and
protocol connected) until the ata host is removed. This means that
no devices can be chained (neither other pata_parport devices nor
a printer).

paride and pata_parport are mutually exclusive because the compiled
protocol drivers are incompatible.

Tested with:
 - Imation SuperDisk LS-120 and HP C4381A (EPAT)
 - Freecom Parallel CD (FRPW)
 - Toshiba Mobile CD-RW 2793008 w/Freecom Parallel Cable rev.903 (FRIQ)
 - Backpack CD-RW 222011 and CD-RW 19350 (BPCK6)

The following bugs in low-level protocol drivers were found and will
be fixed later:

Note: EPP-32 mode is buggy in EPAT - and also in all other protocol
drivers - they don't handle non-multiple-of-4 block transfers
correctly. This causes problems with LS-120 drive.
There is also another bug in EPAT: EPP modes don't work unless a 4-bit
or 8-bit mode is used first (probably some initialization missing?).
Once the device is initialized, EPP works until power cycle.

So after device power on, you have to:
echo "parport0 epat 0" >/sys/bus/pata_parport/new_device
echo pata_parport.0 >/sys/bus/pata_parport/delete_device
echo "parport0 epat 4" >/sys/bus/pata_parport/new_device
(autoprobe will initialize correctly as it tries the slowest modes
first but you'll get the broken EPP-32 mode)

Note: EPP modes are buggy in FRPW, only modes 0 and 1 work.

Signed-off-by: Ondrej Zary <linux@zary.sk>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

3 files changed, 775 insertions, 0 deletions

diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index eceaec33af65..fb646480635c 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -1162,6 +1162,20 @@ config PATA_WINBOND_VLB
 	  Support for the Winbond W83759A controller on Vesa Local Bus
 	  systems.
 
+config PATA_PARPORT
+	tristate "Parallel port IDE device support"
+	depends on PARPORT_PC && PARIDE=n
+	help
+	  There are many external CD-ROM and disk devices that connect through
+	  your computer's parallel port. Most of them are actually IDE devices
+	  using a parallel port IDE adapter. This option enables the
+	  PATA_PARPORT subsystem which contains drivers for many of these
+	  external drives.
+	  Read <file:Documentation/admin-guide/blockdev/paride.rst> for more
+	  information.
+
+	  Use the old PARIDE protocol modules.
+
 comment "Generic fallback / legacy drivers"
 
 config PATA_ACPI
diff --git a/drivers/ata/Makefile b/drivers/ata/Makefile
index d2e36d367274..23588738cff0 100644
--- a/drivers/ata/Makefile
+++ b/drivers/ata/Makefile
@@ -114,6 +114,8 @@ obj-$(CONFIG_PATA_SAMSUNG_CF)	+= pata_samsung_cf.o
 
 obj-$(CONFIG_PATA_PXA)		+= pata_pxa.o
 
+obj-$(CONFIG_PATA_PARPORT)	+= pata_parport.o
+
 # Should be last but two libata driver
 obj-$(CONFIG_PATA_ACPI)		+= pata_acpi.o
 # Should be last but one libata driver
diff --git a/drivers/ata/pata_parport.c b/drivers/ata/pata_parport.c
new file mode 100644
index 000000000000..9e8ad93d7e59
--- /dev/null
+++ b/drivers/ata/pata_parport.c
@@ -0,0 +1,759 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Ondrej Zary
+ * based on paride.c by Grant R. Guenther <grant@torque.net>
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/parport.h>
+#include <linux/pata_parport.h>
+
+#define DRV_NAME "pata_parport"
+
+static DEFINE_IDR(parport_list);
+static DEFINE_IDR(protocols);
+static DEFINE_IDA(pata_parport_bus_dev_ids);
+static DEFINE_MUTEX(pi_mutex);
+
+static bool probe = true;
+module_param(probe, bool, 0644);
+MODULE_PARM_DESC(probe, "Enable automatic device probing (0=off, 1=on [default])");
+
+/*
+ * libata drivers cannot sleep so this driver claims parport before activating
+ * the ata host and keeps it claimed (and protocol connected) until the ata
+ * host is removed. Unfortunately, this means that you cannot use any chained
+ * devices (neither other pata_parport devices nor a printer).
+ */
+static void pi_connect(struct pi_adapter *pi)
+{
+	parport_claim_or_block(pi->pardev);
+	pi->proto->connect(pi);
+}
+
+static void pi_disconnect(struct pi_adapter *pi)
+{
+	pi->proto->disconnect(pi);
+	parport_release(pi->pardev);
+}
+
+static void pata_parport_dev_select(struct ata_port *ap, unsigned int device)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+	u8 tmp;
+
+	if (device == 0)
+		tmp = ATA_DEVICE_OBS;
+	else
+		tmp = ATA_DEVICE_OBS | ATA_DEV1;
+
+	pi->proto->write_regr(pi, 0, ATA_REG_DEVICE, tmp);
+	ata_sff_pause(ap);
+}
+
+static bool pata_parport_devchk(struct ata_port *ap, unsigned int device)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+	u8 nsect, lbal;
+
+	pata_parport_dev_select(ap, device);
+
+	pi->proto->write_regr(pi, 0, ATA_REG_NSECT, 0x55);
+	pi->proto->write_regr(pi, 0, ATA_REG_LBAL, 0xaa);
+
+	pi->proto->write_regr(pi, 0, ATA_REG_NSECT, 0xaa);
+	pi->proto->write_regr(pi, 0, ATA_REG_LBAL, 0x55);
+
+	pi->proto->write_regr(pi, 0, ATA_REG_NSECT, 055);
+	pi->proto->write_regr(pi, 0, ATA_REG_LBAL, 0xaa);
+
+	nsect = pi->proto->read_regr(pi, 0, ATA_REG_NSECT);
+	lbal = pi->proto->read_regr(pi, 0, ATA_REG_LBAL);
+
+	return (nsect == 0x55) && (lbal == 0xaa);
+}
+
+static int pata_parport_bus_softreset(struct ata_port *ap, unsigned int devmask,
+				      unsigned long deadline)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+
+	/* software reset.  causes dev0 to be selected */
+	pi->proto->write_regr(pi, 1, 6, ap->ctl);
+	udelay(20);
+	pi->proto->write_regr(pi, 1, 6, ap->ctl | ATA_SRST);
+	udelay(20);
+	pi->proto->write_regr(pi, 1, 6, ap->ctl);
+	ap->last_ctl = ap->ctl;
+
+	/* wait the port to become ready */
+	return ata_sff_wait_after_reset(&ap->link, devmask, deadline);
+}
+
+static int pata_parport_softreset(struct ata_link *link, unsigned int *classes,
+				  unsigned long deadline)
+{
+	struct ata_port *ap = link->ap;
+	unsigned int devmask = 0;
+	int rc;
+	u8 err;
+
+	/* determine if device 0/1 are present */
+	if (pata_parport_devchk(ap, 0))
+		devmask |= (1 << 0);
+	if (pata_parport_devchk(ap, 1))
+		devmask |= (1 << 1);
+
+	/* select device 0 again */
+	pata_parport_dev_select(ap, 0);
+
+	/* issue bus reset */
+	rc = pata_parport_bus_softreset(ap, devmask, deadline);
+	if (rc && rc != -ENODEV) {
+		ata_link_err(link, "SRST failed (errno=%d)\n", rc);
+		return rc;
+	}
+
+	/* determine by signature whether we have ATA or ATAPI devices */
+	classes[0] = ata_sff_dev_classify(&link->device[0],
+					  devmask & (1 << 0), &err);
+	if (err != 0x81)
+		classes[1] = ata_sff_dev_classify(&link->device[1],
+						  devmask & (1 << 1), &err);
+
+	return 0;
+}
+
+static u8 pata_parport_check_status(struct ata_port *ap)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+
+	return pi->proto->read_regr(pi, 0, ATA_REG_STATUS);
+}
+
+static u8 pata_parport_check_altstatus(struct ata_port *ap)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+
+	return pi->proto->read_regr(pi, 1, 6);
+}
+
+static void pata_parport_tf_load(struct ata_port *ap,
+				 const struct ata_taskfile *tf)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+
+	if (tf->ctl != ap->last_ctl) {
+		pi->proto->write_regr(pi, 1, 6, tf->ctl);
+		ap->last_ctl = tf->ctl;
+		ata_wait_idle(ap);
+	}
+
+	if (tf->flags & ATA_TFLAG_ISADDR) {
+		if (tf->flags & ATA_TFLAG_LBA48) {
+			pi->proto->write_regr(pi, 0, ATA_REG_FEATURE,
+					      tf->hob_feature);
+			pi->proto->write_regr(pi, 0, ATA_REG_NSECT,
+					      tf->hob_nsect);
+			pi->proto->write_regr(pi, 0, ATA_REG_LBAL,
+					      tf->hob_lbal);
+			pi->proto->write_regr(pi, 0, ATA_REG_LBAM,
+					      tf->hob_lbam);
+			pi->proto->write_regr(pi, 0, ATA_REG_LBAH,
+					      tf->hob_lbah);
+		}
+		pi->proto->write_regr(pi, 0, ATA_REG_FEATURE, tf->feature);
+		pi->proto->write_regr(pi, 0, ATA_REG_NSECT, tf->nsect);
+		pi->proto->write_regr(pi, 0, ATA_REG_LBAL, tf->lbal);
+		pi->proto->write_regr(pi, 0, ATA_REG_LBAM, tf->lbam);
+		pi->proto->write_regr(pi, 0, ATA_REG_LBAH, tf->lbah);
+	}
+
+	if (tf->flags & ATA_TFLAG_DEVICE)
+		pi->proto->write_regr(pi, 0, ATA_REG_DEVICE, tf->device);
+
+	ata_wait_idle(ap);
+}
+
+static void pata_parport_tf_read(struct ata_port *ap, struct ata_taskfile *tf)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+
+	tf->status = pi->proto->read_regr(pi, 0, ATA_REG_STATUS);
+	tf->error = pi->proto->read_regr(pi, 0, ATA_REG_ERR);
+	tf->nsect = pi->proto->read_regr(pi, 0, ATA_REG_NSECT);
+	tf->lbal = pi->proto->read_regr(pi, 0, ATA_REG_LBAL);
+	tf->lbam = pi->proto->read_regr(pi, 0, ATA_REG_LBAM);
+	tf->lbah = pi->proto->read_regr(pi, 0, ATA_REG_LBAH);
+	tf->device = pi->proto->read_regr(pi, 0, ATA_REG_DEVICE);
+
+	if (tf->flags & ATA_TFLAG_LBA48) {
+		pi->proto->write_regr(pi, 1, 6, tf->ctl | ATA_HOB);
+		tf->hob_feature = pi->proto->read_regr(pi, 0, ATA_REG_ERR);
+		tf->hob_nsect = pi->proto->read_regr(pi, 0, ATA_REG_NSECT);
+		tf->hob_lbal = pi->proto->read_regr(pi, 0, ATA_REG_LBAL);
+		tf->hob_lbam = pi->proto->read_regr(pi, 0, ATA_REG_LBAM);
+		tf->hob_lbah = pi->proto->read_regr(pi, 0, ATA_REG_LBAH);
+		pi->proto->write_regr(pi, 1, 6, tf->ctl);
+		ap->last_ctl = tf->ctl;
+	}
+}
+
+static void pata_parport_exec_command(struct ata_port *ap,
+				      const struct ata_taskfile *tf)
+{
+	struct pi_adapter *pi = ap->host->private_data;
+
+	pi->proto->write_regr(pi, 0, ATA_REG_CMD, tf->command);
+	ata_sff_pause(ap);
+}
+
+static unsigned int pata_parport_data_xfer(struct ata_queued_cmd *qc,
+				unsigned char *buf, unsigned int buflen, int rw)
+{
+	struct ata_port *ap = qc->dev->link->ap;
+	struct pi_adapter *pi = ap->host->private_data;
+
+	if (rw == READ)
+		pi->proto->read_block(pi, buf, buflen);
+	else
+		pi->proto->write_block(pi, buf, buflen);
+
+	return buflen;
+}
+
+static void pata_parport_drain_fifo(struct ata_queued_cmd *qc)
+{
+	int count;
+	struct ata_port *ap;
+	struct pi_adapter *pi;
+	char junk[2];
+
+	/* We only need to flush incoming data when a command was running */
+	if (qc == NULL || qc->dma_dir == DMA_TO_DEVICE)
+		return;
+
+	ap = qc->ap;
+	pi = ap->host->private_data;
+	/* Drain up to 64K of data before we give up this recovery method */
+	for (count = 0; (pata_parport_check_status(ap) & ATA_DRQ)
+						&& count < 65536; count += 2) {
+		pi->proto->read_block(pi, junk, 2);
+	}
+
+	if (count)
+		ata_port_dbg(ap, "drained %d bytes to clear DRQ\n", count);
+}
+
+static struct ata_port_operations pata_parport_port_ops = {
+	.inherits		= &ata_sff_port_ops,
+
+	.softreset		= pata_parport_softreset,
+	.hardreset		= NULL,
+
+	.sff_dev_select		= pata_parport_dev_select,
+	.sff_check_status	= pata_parport_check_status,
+	.sff_check_altstatus	= pata_parport_check_altstatus,
+	.sff_tf_load		= pata_parport_tf_load,
+	.sff_tf_read		= pata_parport_tf_read,
+	.sff_exec_command	= pata_parport_exec_command,
+	.sff_data_xfer		= pata_parport_data_xfer,
+	.sff_drain_fifo		= pata_parport_drain_fifo,
+};
+
+static const struct ata_port_info pata_parport_port_info = {
+	.flags		= ATA_FLAG_SLAVE_POSS | ATA_FLAG_PIO_POLLING,
+	.pio_mask	= ATA_PIO0,
+	/* No DMA */
+	.port_ops	= &pata_parport_port_ops,
+};
+
+static void pi_release(struct pi_adapter *pi)
+{
+	parport_unregister_device(pi->pardev);
+	if (pi->proto->release_proto)
+		pi->proto->release_proto(pi);
+	module_put(pi->proto->owner);
+}
+
+static int default_test_proto(struct pi_adapter *pi, char *scratch)
+{
+	int j, k;
+	int e[2] = { 0, 0 };
+
+	pi->proto->connect(pi);
+
+	for (j = 0; j < 2; j++) {
+		pi->proto->write_regr(pi, 0, 6, 0xa0 + j * 0x10);
+		for (k = 0; k < 256; k++) {
+			pi->proto->write_regr(pi, 0, 2, k ^ 0xaa);
+			pi->proto->write_regr(pi, 0, 3, k ^ 0x55);
+			if (pi->proto->read_regr(pi, 0, 2) != (k ^ 0xaa))
+				e[j]++;
+		}
+	}
+	pi->proto->disconnect(pi);
+
+	dev_dbg(&pi->dev, "%s: port 0x%x, mode %d, test=(%d,%d)\n",
+		pi->proto->name, pi->port, pi->mode, e[0], e[1]);
+
+	return e[0] && e[1];	/* not here if both > 0 */
+}
+
+static int pi_test_proto(struct pi_adapter *pi, char *scratch)
+{
+	int res;
+
+	parport_claim_or_block(pi->pardev);
+	if (pi->proto->test_proto)
+		res = pi->proto->test_proto(pi, scratch, 1);
+	else
+		res = default_test_proto(pi, scratch);
+	parport_release(pi->pardev);
+
+	return res;
+}
+
+static bool pi_probe_mode(struct pi_adapter *pi, int max, char *scratch)
+{
+	int best, range;
+
+	if (pi->mode != -1) {
+		if (pi->mode >= max)
+			return false;
+		range = 3;
+		if (pi->mode >= pi->proto->epp_first)
+			range = 8;
+		if (range == 8 && pi->port % 8)
+			return false;
+		return !pi_test_proto(pi, scratch);
+	}
+	best = -1;
+	for (pi->mode = 0; pi->mode < max; pi->mode++) {
+		range = 3;
+		if (pi->mode >= pi->proto->epp_first)
+			range = 8;
+		if (range == 8 && pi->port % 8)
+			break;
+		if (!pi_test_proto(pi, scratch))
+			best = pi->mode;
+	}
+	pi->mode = best;
+	return best > -1;
+}
+
+static bool pi_probe_unit(struct pi_adapter *pi, int unit, char *scratch)
+{
+	int max, s, e;
+
+	s = unit;
+	e = s + 1;
+
+	if (s == -1) {
+		s = 0;
+		e = pi->proto->max_units;
+	}
+
+	if (pi->proto->test_port) {
+		parport_claim_or_block(pi->pardev);
+		max = pi->proto->test_port(pi);
+		parport_release(pi->pardev);
+	} else {
+		max = pi->proto->max_mode;
+	}
+
+	if (pi->proto->probe_unit) {
+		parport_claim_or_block(pi->pardev);
+		for (pi->unit = s; pi->unit < e; pi->unit++) {
+			if (pi->proto->probe_unit(pi)) {
+				parport_release(pi->pardev);
+				return pi_probe_mode(pi, max, scratch);
+			}
+		}
+		parport_release(pi->pardev);
+		return false;
+	}
+
+	return pi_probe_mode(pi, max, scratch);
+}
+
+static void pata_parport_dev_release(struct device *dev)
+{
+	struct pi_adapter *pi = container_of(dev, struct pi_adapter, dev);
+
+	kfree(pi);
+}
+
+static void pata_parport_bus_release(struct device *dev)
+{
+	/* nothing to do here but required to avoid warning on device removal */
+}
+
+static struct bus_type pata_parport_bus_type = {
+	.name = DRV_NAME,
+};
+
+static struct device pata_parport_bus = {
+	.init_name = DRV_NAME,
+	.release = pata_parport_bus_release,
+};
+
+static struct scsi_host_template pata_parport_sht = {
+	PATA_PARPORT_SHT("pata_parport")
+};
+
+struct pi_device_match {
+	struct parport *parport;
+	struct pi_protocol *proto;
+};
+
+static int pi_find_dev(struct device *dev, void *data)
+{
+	struct pi_adapter *pi = container_of(dev, struct pi_adapter, dev);
+	struct pi_device_match *match = data;
+
+	return pi->pardev->port == match->parport && pi->proto == match->proto;
+}
+
+static struct pi_adapter *pi_init_one(struct parport *parport,
+			struct pi_protocol *pr, int mode, int unit, int delay)
+{
+	struct pardev_cb par_cb = { };
+	char scratch[512];
+	const struct ata_port_info *ppi[] = { &pata_parport_port_info };
+	struct ata_host *host;
+	struct pi_adapter *pi;
+	struct pi_device_match match = { .parport = parport, .proto = pr };
+
+	/*
+	 * Abort if there's a device already registered on the same parport
+	 * using the same protocol.
+	 */
+	if (bus_for_each_dev(&pata_parport_bus_type, NULL, &match, pi_find_dev))
+		return NULL;
+
+	pi = kzalloc(sizeof(struct pi_adapter), GFP_KERNEL);
+	if (!pi)
+		return NULL;
+
+	/* set up pi->dev before pi_probe_unit() so it can use dev_printk() */
+	pi->dev.parent = &pata_parport_bus;
+	pi->dev.bus = &pata_parport_bus_type;
+	pi->dev.driver = &pr->driver;
+	pi->dev.release = pata_parport_dev_release;
+	pi->dev.id = ida_alloc(&pata_parport_bus_dev_ids, GFP_KERNEL);
+	if (pi->dev.id < 0)
+		return NULL; /* pata_parport_dev_release will do kfree(pi) */
+	dev_set_name(&pi->dev, "pata_parport.%u", pi->dev.id);
+	if (device_register(&pi->dev)) {
+		put_device(&pi->dev);
+		goto out_ida_free;
+	}
+
+	pi->proto = pr;
+
+	if (!try_module_get(pi->proto->owner))
+		goto out_unreg_dev;
+	if (pi->proto->init_proto && pi->proto->init_proto(pi) < 0)
+		goto out_module_put;
+
+	pi->delay = (delay == -1) ? pi->proto->default_delay : delay;
+	pi->mode = mode;
+	pi->port = parport->base;
+
+	par_cb.private = pi;
+	pi->pardev = parport_register_dev_model(parport, DRV_NAME, &par_cb,
+						pi->dev.id);
+	if (!pi->pardev)
+		goto out_module_put;
+
+	if (!pi_probe_unit(pi, unit, scratch)) {
+		dev_info(&pi->dev, "Adapter not found\n");
+		goto out_unreg_parport;
+	}
+
+	pi->proto->log_adapter(pi, scratch, 1);
+
+	host = ata_host_alloc_pinfo(&pi->pardev->dev, ppi, 1);
+	if (!host)
+		goto out_unreg_parport;
+	dev_set_drvdata(&pi->dev, host);
+	host->private_data = pi;
+
+	ata_port_desc(host->ports[0], "port %s", pi->pardev->port->name);
+	ata_port_desc(host->ports[0], "protocol %s", pi->proto->name);
+
+	pi_connect(pi);
+	if (ata_host_activate(host, 0, NULL, 0, &pata_parport_sht))
+		goto out_unreg_parport;
+
+	return pi;
+
+out_unreg_parport:
+	pi_disconnect(pi);
+	parport_unregister_device(pi->pardev);
+	if (pi->proto->release_proto)
+		pi->proto->release_proto(pi);
+out_module_put:
+	module_put(pi->proto->owner);
+out_unreg_dev:
+	device_unregister(&pi->dev);
+out_ida_free:
+	ida_free(&pata_parport_bus_dev_ids, pi->dev.id);
+	return NULL;
+}
+
+int pata_parport_register_driver(struct pi_protocol *pr)
+{
+	int error;
+	struct parport *parport;
+	int port_num;
+
+	pr->driver.bus = &pata_parport_bus_type;
+	pr->driver.name = pr->name;
+	error = driver_register(&pr->driver);
+	if (error)
+		return error;
+
+	mutex_lock(&pi_mutex);
+	error = idr_alloc(&protocols, pr, 0, 0, GFP_KERNEL);
+	if (error < 0) {
+		driver_unregister(&pr->driver);
+		mutex_unlock(&pi_mutex);
+		return error;
+	}
+
+	pr_info("pata_parport: protocol %s registered\n", pr->name);
+
+	if (probe) {
+		/* probe all parports using this protocol */
+		idr_for_each_entry(&parport_list, parport, port_num)
+			pi_init_one(parport, pr, -1, 0, -1);
+	}
+	mutex_unlock(&pi_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pata_parport_register_driver);
+
+void pata_parport_unregister_driver(struct pi_protocol *pr)
+{
+	struct pi_protocol *pr_iter;
+	int id = -1;
+
+	mutex_lock(&pi_mutex);
+	idr_for_each_entry(&protocols, pr_iter, id) {
+		if (pr_iter == pr)
+			break;
+	}
+	idr_remove(&protocols, id);
+	mutex_unlock(&pi_mutex);
+	driver_unregister(&pr->driver);
+}
+EXPORT_SYMBOL_GPL(pata_parport_unregister_driver);
+
+static ssize_t new_device_store(struct bus_type *bus, const char *buf,
+				size_t count)
+{
+	char port[12] = "auto";
+	char protocol[8] = "auto";
+	int mode = -1, unit = -1, delay = -1;
+	struct pi_protocol *pr, *pr_wanted;
+	struct device_driver *drv;
+	struct parport *parport;
+	int port_num, port_wanted, pr_num;
+	bool ok = false;
+
+	if (sscanf(buf, "%11s %7s %d %d %d",
+			port, protocol, &mode, &unit, &delay) < 1)
+		return -EINVAL;
+
+	if (sscanf(port, "parport%u", &port_wanted) < 1) {
+		if (strcmp(port, "auto")) {
+			pr_err("invalid port name %s\n", port);
+			return -EINVAL;
+		}
+		port_wanted = -1;
+	}
+
+	drv = driver_find(protocol, &pata_parport_bus_type);
+	if (!drv) {
+		if (strcmp(protocol, "auto")) {
+			pr_err("protocol %s not found\n", protocol);
+			return -EINVAL;
+		}
+		pr_wanted = NULL;
+	} else {
+		pr_wanted = container_of(drv, struct pi_protocol, driver);
+	}
+
+	mutex_lock(&pi_mutex);
+	/* walk all parports */
+	idr_for_each_entry(&parport_list, parport, port_num) {
+		if (port_num == port_wanted || port_wanted == -1) {
+			parport = parport_find_number(port_num);
+			if (!parport) {
+				pr_err("no such port %s\n", port);
+				mutex_unlock(&pi_mutex);
+				return -ENODEV;
+			}
+			/* walk all protocols */
+			idr_for_each_entry(&protocols, pr, pr_num) {
+				if (pr == pr_wanted || !pr_wanted)
+					if (pi_init_one(parport, pr, mode, unit,
+							delay))
+						ok = true;
+			}
+			parport_put_port(parport);
+		}
+	}
+	mutex_unlock(&pi_mutex);
+	if (!ok)
+		return -ENODEV;
+
+	return count;
+}
+static BUS_ATTR_WO(new_device);
+
+static void pi_remove_one(struct device *dev)
+{
+	struct ata_host *host = dev_get_drvdata(dev);
+	struct pi_adapter *pi = host->private_data;
+
+	ata_host_detach(host);
+	pi_disconnect(pi);
+	pi_release(pi);
+	device_unregister(dev);
+	ida_free(&pata_parport_bus_dev_ids, dev->id);
+	/* pata_parport_dev_release will do kfree(pi) */
+}
+
+static ssize_t delete_device_store(struct bus_type *bus, const char *buf,
+				   size_t count)
+{
+	struct device *dev;
+
+	mutex_lock(&pi_mutex);
+	dev = bus_find_device_by_name(bus, NULL, buf);
+	if (!dev) {
+		mutex_unlock(&pi_mutex);
+		return -ENODEV;
+	}
+
+	pi_remove_one(dev);
+	mutex_unlock(&pi_mutex);
+
+	return count;
+}
+static BUS_ATTR_WO(delete_device);
+
+static void pata_parport_attach(struct parport *port)
+{
+	struct pi_protocol *pr;
+	int pr_num, id;
+
+	mutex_lock(&pi_mutex);
+	id = idr_alloc(&parport_list, port, port->number, port->number,
+		       GFP_KERNEL);
+	if (id < 0) {
+		mutex_unlock(&pi_mutex);
+		return;
+	}
+
+	if (probe) {
+		/* probe this port using all protocols */
+		idr_for_each_entry(&protocols, pr, pr_num)
+			pi_init_one(port, pr, -1, 0, -1);
+	}
+	mutex_unlock(&pi_mutex);
+}
+
+static int pi_remove_port(struct device *dev, void *p)
+{
+	struct ata_host *host = dev_get_drvdata(dev);
+	struct pi_adapter *pi = host->private_data;
+
+	if (pi->pardev->port == p)
+		pi_remove_one(dev);
+
+	return 0;
+}
+
+static void pata_parport_detach(struct parport *port)
+{
+	mutex_lock(&pi_mutex);
+	bus_for_each_dev(&pata_parport_bus_type, NULL, port, pi_remove_port);
+	idr_remove(&parport_list, port->number);
+	mutex_unlock(&pi_mutex);
+}
+
+static struct parport_driver pata_parport_driver = {
+	.name = DRV_NAME,
+	.match_port = pata_parport_attach,
+	.detach = pata_parport_detach,
+	.devmodel = true,
+};
+
+static __init int pata_parport_init(void)
+{
+	int error;
+
+	error = bus_register(&pata_parport_bus_type);
+	if (error) {
+		pr_err("failed to register pata_parport bus, error: %d\n", error);
+		return error;
+	}
+
+	error = device_register(&pata_parport_bus);
+	if (error) {
+		pr_err("failed to register pata_parport bus, error: %d\n", error);
+		goto out_unregister_bus;
+	}
+
+	error = bus_create_file(&pata_parport_bus_type, &bus_attr_new_device);
+	if (error) {
+		pr_err("unable to create sysfs file, error: %d\n", error);
+		goto out_unregister_dev;
+	}
+
+	error = bus_create_file(&pata_parport_bus_type, &bus_attr_delete_device);
+	if (error) {
+		pr_err("unable to create sysfs file, error: %d\n", error);
+		goto out_remove_new;
+	}
+
+	error = parport_register_driver(&pata_parport_driver);
+	if (error) {
+		pr_err("unable to register parport driver, error: %d\n", error);
+		goto out_remove_del;
+	}
+
+	return 0;
+
+out_remove_del:
+	bus_remove_file(&pata_parport_bus_type, &bus_attr_delete_device);
+out_remove_new:
+	bus_remove_file(&pata_parport_bus_type, &bus_attr_new_device);
+out_unregister_dev:
+	device_unregister(&pata_parport_bus);
+out_unregister_bus:
+	bus_unregister(&pata_parport_bus_type);
+	return error;
+}
+
+static __exit void pata_parport_exit(void)
+{
+	parport_unregister_driver(&pata_parport_driver);
+	bus_remove_file(&pata_parport_bus_type, &bus_attr_new_device);
+	bus_remove_file(&pata_parport_bus_type, &bus_attr_delete_device);
+	device_unregister(&pata_parport_bus);
+	bus_unregister(&pata_parport_bus_type);
+}
+
+MODULE_AUTHOR("Ondrej Zary");
+MODULE_DESCRIPTION("driver for parallel port ATA adapters");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("paride");
+
+module_init(pata_parport_init);
+module_exit(pata_parport_exit);