Merging upstream version 6.7.7.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

44 files changed, 592 insertions, 341 deletions

diff --git a/drivers/comedi/Kconfig b/drivers/comedi/Kconfig
index 9af280735c..93c68a40a1 100644
--- a/drivers/comedi/Kconfig
+++ b/drivers/comedi/Kconfig
@@ -67,6 +67,7 @@ config COMEDI_TEST
 
 config COMEDI_PARPORT
 	tristate "Parallel port support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for the standard parallel port.
 	  A cheap and easy way to get a few more digital I/O lines. Steal
@@ -79,6 +80,7 @@ config COMEDI_PARPORT
 config COMEDI_SSV_DNP
 	tristate "SSV Embedded Systems DIL/Net-PC support"
 	depends on X86_32 || COMPILE_TEST
+	depends on HAS_IOPORT
 	help
 	  Enable support for SSV Embedded Systems DIL/Net-PC
 
@@ -89,6 +91,8 @@ endif # COMEDI_MISC_DRIVERS
 
 menuconfig COMEDI_ISA_DRIVERS
 	bool "Comedi ISA and PC/104 drivers"
+	depends on ISA || ISA_BUS || PC104
+	depends on HAS_IOPORT
 	help
 	  Enable comedi ISA and PC/104 drivers to be built
 
@@ -589,6 +593,7 @@ config COMEDI_8255_PCI
 
 config COMEDI_ADDI_WATCHDOG
 	tristate
+	depends on HAS_IOPORT
 	help
 	  Provides support for the watchdog subdevice found on many ADDI-DATA
 	  boards. This module will be automatically selected when needed. The
@@ -596,6 +601,7 @@ config COMEDI_ADDI_WATCHDOG
 
 config COMEDI_ADDI_APCI_1032
 	tristate "ADDI-DATA APCI_1032 support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADDI-DATA APCI_1032 cards
 
@@ -604,6 +610,7 @@ config COMEDI_ADDI_APCI_1032
 
 config COMEDI_ADDI_APCI_1500
 	tristate "ADDI-DATA APCI_1500 support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADDI-DATA APCI_1500 cards
 
@@ -612,6 +619,7 @@ config COMEDI_ADDI_APCI_1500
 
 config COMEDI_ADDI_APCI_1516
 	tristate "ADDI-DATA APCI-1016/1516/2016 support"
+	depends on HAS_IOPORT
 	select COMEDI_ADDI_WATCHDOG
 	help
 	  Enable support for ADDI-DATA APCI-1016, APCI-1516 and APCI-2016 boards.
@@ -623,6 +631,7 @@ config COMEDI_ADDI_APCI_1516
 
 config COMEDI_ADDI_APCI_1564
 	tristate "ADDI-DATA APCI_1564 support"
+	depends on HAS_IOPORT
 	select COMEDI_ADDI_WATCHDOG
 	help
 	  Enable support for ADDI-DATA APCI_1564 cards
@@ -632,6 +641,7 @@ config COMEDI_ADDI_APCI_1564
 
 config COMEDI_ADDI_APCI_16XX
 	tristate "ADDI-DATA APCI_16xx support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADDI-DATA APCI_16xx cards
 
@@ -640,6 +650,7 @@ config COMEDI_ADDI_APCI_16XX
 
 config COMEDI_ADDI_APCI_2032
 	tristate "ADDI-DATA APCI_2032 support"
+	depends on HAS_IOPORT
 	select COMEDI_ADDI_WATCHDOG
 	help
 	  Enable support for ADDI-DATA APCI_2032 cards
@@ -649,6 +660,7 @@ config COMEDI_ADDI_APCI_2032
 
 config COMEDI_ADDI_APCI_2200
 	tristate "ADDI-DATA APCI_2200 support"
+	depends on HAS_IOPORT
 	select COMEDI_ADDI_WATCHDOG
 	help
 	  Enable support for ADDI-DATA APCI_2200 cards
@@ -658,6 +670,7 @@ config COMEDI_ADDI_APCI_2200
 
 config COMEDI_ADDI_APCI_3120
 	tristate "ADDI-DATA APCI_3120/3001 support"
+	depends on HAS_IOPORT
 	depends on HAS_DMA
 	help
 	  Enable support for ADDI-DATA APCI_3120/3001 cards
@@ -667,6 +680,7 @@ config COMEDI_ADDI_APCI_3120
 
 config COMEDI_ADDI_APCI_3501
 	tristate "ADDI-DATA APCI_3501 support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADDI-DATA APCI_3501 cards
 
@@ -675,6 +689,7 @@ config COMEDI_ADDI_APCI_3501
 
 config COMEDI_ADDI_APCI_3XXX
 	tristate "ADDI-DATA APCI_3xxx support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADDI-DATA APCI_3xxx cards
 
@@ -683,6 +698,7 @@ config COMEDI_ADDI_APCI_3XXX
 
 config COMEDI_ADL_PCI6208
 	tristate "ADLink PCI-6208A support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADLink PCI-6208A cards
 
@@ -691,6 +707,7 @@ config COMEDI_ADL_PCI6208
 
 config COMEDI_ADL_PCI7X3X
 	tristate "ADLink PCI-723X/743X isolated digital i/o board support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADlink PCI-723X/743X isolated digital i/o boards.
 	  Supported boards include the 32-channel PCI-7230 (16 in/16 out),
@@ -702,6 +719,7 @@ config COMEDI_ADL_PCI7X3X
 
 config COMEDI_ADL_PCI8164
 	tristate "ADLink PCI-8164 4 Axes Motion Control board support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for ADlink PCI-8164 4 Axes Motion Control board
 
@@ -710,6 +728,7 @@ config COMEDI_ADL_PCI8164
 
 config COMEDI_ADL_PCI9111
 	tristate "ADLink PCI-9111HR support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	help
 	  Enable support for ADlink PCI9111 cards
@@ -719,6 +738,7 @@ config COMEDI_ADL_PCI9111
 
 config COMEDI_ADL_PCI9118
 	tristate "ADLink PCI-9118DG, PCI-9118HG, PCI-9118HR support"
+	depends on HAS_IOPORT
 	depends on HAS_DMA
 	select COMEDI_8254
 	help
@@ -729,6 +749,7 @@ config COMEDI_ADL_PCI9118
 
 config COMEDI_ADV_PCI1710
 	tristate "Advantech PCI-171x and PCI-1731 support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	help
 	  Enable support for Advantech PCI-1710, PCI-1710HG, PCI-1711,
@@ -739,6 +760,7 @@ config COMEDI_ADV_PCI1710
 
 config COMEDI_ADV_PCI1720
 	tristate "Advantech PCI-1720 support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for Advantech PCI-1720 Analog Output board.
 
@@ -747,6 +769,7 @@ config COMEDI_ADV_PCI1720
 
 config COMEDI_ADV_PCI1723
 	tristate "Advantech PCI-1723 support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for Advantech PCI-1723 cards
 
@@ -755,6 +778,7 @@ config COMEDI_ADV_PCI1723
 
 config COMEDI_ADV_PCI1724
 	tristate "Advantech PCI-1724U support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for Advantech PCI-1724U cards.  These are 32-channel
 	  analog output cards with voltage and current loop output ranges and
@@ -765,6 +789,7 @@ config COMEDI_ADV_PCI1724
 
 config COMEDI_ADV_PCI1760
 	tristate "Advantech PCI-1760 support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for Advantech PCI-1760 board.
 
@@ -773,6 +798,7 @@ config COMEDI_ADV_PCI1760
 
 config COMEDI_ADV_PCI_DIO
 	tristate "Advantech PCI DIO card support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	select COMEDI_8255
 	help
@@ -796,6 +822,7 @@ config COMEDI_AMPLC_DIO200_PCI
 
 config COMEDI_AMPLC_PC236_PCI
 	tristate "Amplicon PCI236 DIO board support"
+	depends on HAS_IOPORT
 	select COMEDI_AMPLC_PC236
 	help
 	  Enable support for Amplicon PCI236 DIO board.
@@ -805,6 +832,7 @@ config COMEDI_AMPLC_PC236_PCI
 
 config COMEDI_AMPLC_PC263_PCI
 	tristate "Amplicon PCI263 relay board support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for Amplicon PCI263 relay board.  This is a PCI board
 	  with 16 reed relay output channels.
@@ -814,6 +842,7 @@ config COMEDI_AMPLC_PC263_PCI
 
 config COMEDI_AMPLC_PCI224
 	tristate "Amplicon PCI224 and PCI234 support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	help
 	  Enable support for Amplicon PCI224 and PCI234 AO boards
@@ -823,6 +852,7 @@ config COMEDI_AMPLC_PCI224
 
 config COMEDI_AMPLC_PCI230
 	tristate "Amplicon PCI230 and PCI260 support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	select COMEDI_8255
 	help
@@ -834,6 +864,7 @@ config COMEDI_AMPLC_PCI230
 
 config COMEDI_CONTEC_PCI_DIO
 	tristate "Contec PIO1616L digital I/O board support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for the Contec PIO1616L digital I/O board
 
@@ -842,6 +873,7 @@ config COMEDI_CONTEC_PCI_DIO
 
 config COMEDI_DAS08_PCI
 	tristate "DAS-08 PCI support"
+	depends on HAS_IOPORT
 	select COMEDI_DAS08
 	help
 	  Enable support for PCI DAS-08 cards.
@@ -861,6 +893,7 @@ config COMEDI_DT3000
 
 config COMEDI_DYNA_PCI10XX
 	tristate "Dynalog PCI DAQ series support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for Dynalog PCI DAQ series
 	  PCI-1050
@@ -911,6 +944,7 @@ config COMEDI_JR3_PCI
 
 config COMEDI_KE_COUNTER
 	tristate "Kolter-Electronic PCI Counter 1 card support"
+	depends on HAS_IOPORT
 	help
 	  Enable support for Kolter-Electronic PCI Counter 1 cards
 
@@ -929,6 +963,7 @@ config COMEDI_CB_PCIDAS64
 
 config COMEDI_CB_PCIDAS
 	tristate "MeasurementComputing PCI-DAS support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	select COMEDI_8255
 	help
@@ -942,6 +977,7 @@ config COMEDI_CB_PCIDAS
 
 config COMEDI_CB_PCIDDA
 	tristate "MeasurementComputing PCI-DDA series support"
+	depends on HAS_IOPORT
 	select COMEDI_8255
 	help
 	  Enable support for ComputerBoards/MeasurementComputing PCI-DDA
@@ -953,6 +989,7 @@ config COMEDI_CB_PCIDDA
 
 config COMEDI_CB_PCIMDAS
 	tristate "MeasurementComputing PCIM-DAS1602/16, PCIe-DAS1602/16 support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	select COMEDI_8255
 	help
@@ -964,6 +1001,7 @@ config COMEDI_CB_PCIMDAS
 
 config COMEDI_CB_PCIMDDA
 	tristate "MeasurementComputing PCIM-DDA06-16 support"
+	depends on HAS_IOPORT
 	select COMEDI_8255
 	help
 	  Enable support for ComputerBoards/MeasurementComputing PCIM-DDA06-16
@@ -973,6 +1011,7 @@ config COMEDI_CB_PCIMDDA
 
 config COMEDI_ME4000
 	tristate "Meilhaus ME-4000 support"
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	help
 	  Enable support for Meilhaus PCI data acquisition cards
@@ -1042,7 +1081,6 @@ config COMEDI_NI_PCIDIO
 	tristate "NI PCI-DIO32HS, PCI-6533, PCI-6534 support"
 	depends on HAS_DMA
 	select COMEDI_MITE
-	select COMEDI_8255
 	help
 	  Enable support for National Instruments PCI-DIO-32HS, PXI-6533,
 	  PCI-6533 and PCI-6534
@@ -1103,7 +1141,7 @@ endif # COMEDI_PCI_DRIVERS
 
 menuconfig COMEDI_PCMCIA_DRIVERS
 	tristate "Comedi PCMCIA drivers"
-	depends on PCMCIA
+	depends on PCMCIA && HAS_IOPORT
 	help
 	  Enable support for comedi PCMCIA drivers.
 
@@ -1254,6 +1292,7 @@ config COMEDI_8255
 
 config COMEDI_8255_SA
 	tristate "Standalone 8255 support"
+	depends on HAS_IOPORT
 	select COMEDI_8255
 	help
 	  Enable support for 8255 digital I/O as a standalone driver.
@@ -1290,10 +1329,12 @@ config COMEDI_AMPLC_DIO200
 
 config COMEDI_AMPLC_PC236
 	tristate
+	depends on HAS_IOPORT
 	select COMEDI_8255
 
 config COMEDI_DAS08
 	tristate
+	depends on HAS_IOPORT
 	select COMEDI_8254
 	select COMEDI_8255
 
diff --git a/drivers/comedi/drivers.c b/drivers/comedi/drivers.c
index d4e2ed709b..376130bfba 100644
--- a/drivers/comedi/drivers.c
+++ b/drivers/comedi/drivers.c
@@ -177,7 +177,8 @@ static void comedi_device_detach_cleanup(struct comedi_device *dev)
 		dev->n_subdevices = 0;
 	}
 	kfree(dev->private);
-	kfree(dev->pacer);
+	if (!IS_ERR(dev->pacer))
+		kfree(dev->pacer);
 	dev->private = NULL;
 	dev->pacer = NULL;
 	dev->driver = NULL;
diff --git a/drivers/comedi/drivers/8255.c b/drivers/comedi/drivers/8255.c
index ced8ea09d4..f45f7bd1c6 100644
--- a/drivers/comedi/drivers/8255.c
+++ b/drivers/comedi/drivers/8255.c
@@ -80,7 +80,7 @@ static int dev_8255_attach(struct comedi_device *dev,
 		if (ret) {
 			s->type = COMEDI_SUBD_UNUSED;
 		} else {
-			ret = subdev_8255_init(dev, s, NULL, iobase);
+			ret = subdev_8255_io_init(dev, s, iobase);
 			if (ret) {
 				/*
 				 * Release the I/O port region here, as the
diff --git a/drivers/comedi/drivers/8255_pci.c b/drivers/comedi/drivers/8255_pci.c
index 0fec048e3a..8498cabe4d 100644
--- a/drivers/comedi/drivers/8255_pci.c
+++ b/drivers/comedi/drivers/8255_pci.c
@@ -57,6 +57,7 @@
 #include <linux/comedi/comedi_8255.h>
 
 enum pci_8255_boardid {
+#ifdef CONFIG_HAS_IOPORT
 	BOARD_ADLINK_PCI7224,
 	BOARD_ADLINK_PCI7248,
 	BOARD_ADLINK_PCI7296,
@@ -65,6 +66,7 @@ enum pci_8255_boardid {
 	BOARD_CB_PCIDIO48H_OLD,
 	BOARD_CB_PCIDIO48H_NEW,
 	BOARD_CB_PCIDIO96H,
+#endif	/* CONFIG_HAS_IOPORT */
 	BOARD_NI_PCIDIO96,
 	BOARD_NI_PCIDIO96B,
 	BOARD_NI_PXI6508,
@@ -82,6 +84,7 @@ struct pci_8255_boardinfo {
 };
 
 static const struct pci_8255_boardinfo pci_8255_boards[] = {
+#ifdef CONFIG_HAS_IOPORT
 	[BOARD_ADLINK_PCI7224] = {
 		.name		= "adl_pci-7224",
 		.dio_badr	= 2,
@@ -122,6 +125,7 @@ static const struct pci_8255_boardinfo pci_8255_boards[] = {
 		.dio_badr	= 2,
 		.n_8255		= 4,
 	},
+#endif	/* CONFIG_HAS_IOPORT */
 	[BOARD_NI_PCIDIO96] = {
 		.name		= "ni_pci-dio-96",
 		.dio_badr	= 1,
@@ -219,8 +223,11 @@ static int pci_8255_auto_attach(struct comedi_device *dev,
 		dev->mmio = pci_ioremap_bar(pcidev, board->dio_badr);
 		if (!dev->mmio)
 			return -ENOMEM;
-	} else {
+	} else if (IS_ENABLED(CONFIG_HAS_IOPORT)) {
 		dev->iobase = pci_resource_start(pcidev, board->dio_badr);
+	} else {
+		dev_err(dev->class_dev, "error! need I/O port support\n");
+		return -ENXIO;
 	}
 
 	/*
@@ -235,9 +242,9 @@ static int pci_8255_auto_attach(struct comedi_device *dev,
 	for (i = 0; i < board->n_8255; i++) {
 		s = &dev->subdevices[i];
 		if (dev->mmio)
-			ret = subdev_8255_mm_init(dev, s, NULL, i * I8255_SIZE);
+			ret = subdev_8255_mm_init(dev, s, i * I8255_SIZE);
 		else
-			ret = subdev_8255_init(dev, s, NULL, i * I8255_SIZE);
+			ret = subdev_8255_io_init(dev, s, i * I8255_SIZE);
 		if (ret)
 			return ret;
 	}
@@ -259,6 +266,7 @@ static int pci_8255_pci_probe(struct pci_dev *dev,
 }
 
 static const struct pci_device_id pci_8255_pci_table[] = {
+#ifdef CONFIG_HAS_IOPORT
 	{ PCI_VDEVICE(ADLINK, 0x7224), BOARD_ADLINK_PCI7224 },
 	{ PCI_VDEVICE(ADLINK, 0x7248), BOARD_ADLINK_PCI7248 },
 	{ PCI_VDEVICE(ADLINK, 0x7296), BOARD_ADLINK_PCI7296 },
@@ -269,6 +277,7 @@ static const struct pci_device_id pci_8255_pci_table[] = {
 	{ PCI_DEVICE_SUB(PCI_VENDOR_ID_CB, 0x000b, PCI_VENDOR_ID_CB, 0x000b),
 	  .driver_data = BOARD_CB_PCIDIO48H_NEW },
 	{ PCI_VDEVICE(CB, 0x0017), BOARD_CB_PCIDIO96H },
+#endif	/* CONFIG_HAS_IOPORT */
 	{ PCI_VDEVICE(NI, 0x0160), BOARD_NI_PCIDIO96 },
 	{ PCI_VDEVICE(NI, 0x1630), BOARD_NI_PCIDIO96B },
 	{ PCI_VDEVICE(NI, 0x13c0), BOARD_NI_PXI6508 },
diff --git a/drivers/comedi/drivers/adl_pci9111.c b/drivers/comedi/drivers/adl_pci9111.c
index c50f94272a..086d93f40c 100644
--- a/drivers/comedi/drivers/adl_pci9111.c
+++ b/drivers/comedi/drivers/adl_pci9111.c
@@ -647,10 +647,10 @@ static int pci9111_auto_attach(struct comedi_device *dev,
 			dev->irq = pcidev->irq;
 	}
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCI9111_8254_BASE_REG,
-				      I8254_OSC_BASE_2MHZ, I8254_IO16, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCI9111_8254_BASE_REG,
+					  I8254_OSC_BASE_2MHZ, I8254_IO16, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
diff --git a/drivers/comedi/drivers/adl_pci9118.c b/drivers/comedi/drivers/adl_pci9118.c
index 9a816c7183..a76e2666d5 100644
--- a/drivers/comedi/drivers/adl_pci9118.c
+++ b/drivers/comedi/drivers/adl_pci9118.c
@@ -1524,10 +1524,10 @@ static int pci9118_common_attach(struct comedi_device *dev,
 	devpriv->iobase_a = pci_resource_start(pcidev, 0);
 	dev->iobase = pci_resource_start(pcidev, 2);
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCI9118_TIMER_BASE,
-				      I8254_OSC_BASE_4MHZ, I8254_IO32, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCI9118_TIMER_BASE,
+					  I8254_OSC_BASE_4MHZ, I8254_IO32, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	pci9118_reset(dev);
 
diff --git a/drivers/comedi/drivers/adv_pci1710.c b/drivers/comedi/drivers/adv_pci1710.c
index 4f26399682..c49b0f1f52 100644
--- a/drivers/comedi/drivers/adv_pci1710.c
+++ b/drivers/comedi/drivers/adv_pci1710.c
@@ -767,10 +767,10 @@ static int pci1710_auto_attach(struct comedi_device *dev,
 		return ret;
 	dev->iobase = pci_resource_start(pcidev, 2);
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCI171X_TIMER_BASE,
-				      I8254_OSC_BASE_10MHZ, I8254_IO16, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCI171X_TIMER_BASE,
+					  I8254_OSC_BASE_10MHZ, I8254_IO16, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	n_subdevices = 1;	/* all boards have analog inputs */
 	if (board->has_ao)
diff --git a/drivers/comedi/drivers/adv_pci_dio.c b/drivers/comedi/drivers/adv_pci_dio.c
index efa3e46b55..ca80545047 100644
--- a/drivers/comedi/drivers/adv_pci_dio.c
+++ b/drivers/comedi/drivers/adv_pci_dio.c
@@ -642,8 +642,8 @@ static int pci_dio_auto_attach(struct comedi_device *dev,
 
 		for (j = 0; j < d->chans; j++) {
 			s = &dev->subdevices[subdev++];
-			ret = subdev_8255_init(dev, s, NULL,
-					       d->addr + j * I8255_SIZE);
+			ret = subdev_8255_io_init(dev, s,
+						  d->addr + j * I8255_SIZE);
 			if (ret)
 				return ret;
 		}
@@ -664,11 +664,11 @@ static int pci_dio_auto_attach(struct comedi_device *dev,
 	if (board->timer_regbase) {
 		s = &dev->subdevices[subdev++];
 
-		dev->pacer = comedi_8254_init(dev->iobase +
-					      board->timer_regbase,
-					      0, I8254_IO8, 0);
-		if (!dev->pacer)
-			return -ENOMEM;
+		dev->pacer =
+		    comedi_8254_io_alloc(dev->iobase + board->timer_regbase,
+					 0, I8254_IO8, 0);
+		if (IS_ERR(dev->pacer))
+			return PTR_ERR(dev->pacer);
 
 		comedi_8254_subdevice_init(s, dev->pacer);
 	}
diff --git a/drivers/comedi/drivers/aio_aio12_8.c b/drivers/comedi/drivers/aio_aio12_8.c
index 30b8a32204..227a86a3a7 100644
--- a/drivers/comedi/drivers/aio_aio12_8.c
+++ b/drivers/comedi/drivers/aio_aio12_8.c
@@ -206,10 +206,10 @@ static int aio_aio12_8_attach(struct comedi_device *dev,
 	if (ret)
 		return ret;
 
-	dev->pacer = comedi_8254_init(dev->iobase + AIO12_8_8254_BASE_REG,
-				      0, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + AIO12_8_8254_BASE_REG,
+					  0, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
@@ -247,7 +247,7 @@ static int aio_aio12_8_attach(struct comedi_device *dev,
 
 	/* Digital I/O subdevice (8255) */
 	s = &dev->subdevices[2];
-	ret = subdev_8255_init(dev, s, NULL, AIO12_8_8255_BASE_REG);
+	ret = subdev_8255_io_init(dev, s, AIO12_8_8255_BASE_REG);
 	if (ret)
 		return ret;
 
diff --git a/drivers/comedi/drivers/amplc_dio200_common.c b/drivers/comedi/drivers/amplc_dio200_common.c
index ff651f2eb8..b1a9b4c4a1 100644
--- a/drivers/comedi/drivers/amplc_dio200_common.c
+++ b/drivers/comedi/drivers/amplc_dio200_common.c
@@ -86,6 +86,70 @@ struct dio200_subdev_intr {
 	unsigned int active:1;
 };
 
+#ifdef CONFIG_HAS_IOPORT
+
+static unsigned char dio200___read8(struct comedi_device *dev,
+				    unsigned int offset)
+{
+	if (dev->mmio)
+		return readb(dev->mmio + offset);
+	return inb(dev->iobase + offset);
+}
+
+static void dio200___write8(struct comedi_device *dev,
+			    unsigned int offset, unsigned char val)
+{
+	if (dev->mmio)
+		writeb(val, dev->mmio + offset);
+	else
+		outb(val, dev->iobase + offset);
+}
+
+static unsigned int dio200___read32(struct comedi_device *dev,
+				    unsigned int offset)
+{
+	if (dev->mmio)
+		return readl(dev->mmio + offset);
+	return inl(dev->iobase + offset);
+}
+
+static void dio200___write32(struct comedi_device *dev,
+			     unsigned int offset, unsigned int val)
+{
+	if (dev->mmio)
+		writel(val, dev->mmio + offset);
+	else
+		outl(val, dev->iobase + offset);
+}
+
+#else /* CONFIG_HAS_IOPORT */
+
+static unsigned char dio200___read8(struct comedi_device *dev,
+				    unsigned int offset)
+{
+	return readb(dev->mmio + offset);
+}
+
+static void dio200___write8(struct comedi_device *dev,
+			    unsigned int offset, unsigned char val)
+{
+	writeb(val, dev->mmio + offset);
+}
+
+static unsigned int dio200___read32(struct comedi_device *dev,
+				    unsigned int offset)
+{
+	return readl(dev->mmio + offset);
+}
+
+static void dio200___write32(struct comedi_device *dev,
+			     unsigned int offset, unsigned int val)
+{
+	writel(val, dev->mmio + offset);
+}
+
+#endif /* CONFIG_HAS_IOPORT */
+
 static unsigned char dio200_read8(struct comedi_device *dev,
 				  unsigned int offset)
 {
@@ -94,9 +158,7 @@ static unsigned char dio200_read8(struct comedi_device *dev,
 	if (board->is_pcie)
 		offset <<= 3;
 
-	if (dev->mmio)
-		return readb(dev->mmio + offset);
-	return inb(dev->iobase + offset);
+	return dio200___read8(dev, offset);
 }
 
 static void dio200_write8(struct comedi_device *dev,
@@ -107,10 +169,7 @@ static void dio200_write8(struct comedi_device *dev,
 	if (board->is_pcie)
 		offset <<= 3;
 
-	if (dev->mmio)
-		writeb(val, dev->mmio + offset);
-	else
-		outb(val, dev->iobase + offset);
+	dio200___write8(dev, offset, val);
 }
 
 static unsigned int dio200_read32(struct comedi_device *dev,
@@ -121,9 +180,7 @@ static unsigned int dio200_read32(struct comedi_device *dev,
 	if (board->is_pcie)
 		offset <<= 3;
 
-	if (dev->mmio)
-		return readl(dev->mmio + offset);
-	return inl(dev->iobase + offset);
+	return dio200___read32(dev, offset);
 }
 
 static void dio200_write32(struct comedi_device *dev,
@@ -134,10 +191,7 @@ static void dio200_write32(struct comedi_device *dev,
 	if (board->is_pcie)
 		offset <<= 3;
 
-	if (dev->mmio)
-		writel(val, dev->mmio + offset);
-	else
-		outl(val, dev->iobase + offset);
+	dio200___write32(dev, offset, val);
 }
 
 static unsigned int dio200_subdev_8254_offset(struct comedi_device *dev,
@@ -149,9 +203,9 @@ static unsigned int dio200_subdev_8254_offset(struct comedi_device *dev,
 
 	/* get the offset that was passed to comedi_8254_*_init() */
 	if (dev->mmio)
-		offset = i8254->mmio - dev->mmio;
+		offset = (void __iomem *)i8254->context - dev->mmio;
 	else
-		offset = i8254->iobase - dev->iobase;
+		offset = i8254->context - dev->iobase;
 
 	/* remove the shift that was added for PCIe boards */
 	if (board->is_pcie)
@@ -556,14 +610,14 @@ static int dio200_subdev_8254_init(struct comedi_device *dev,
 	}
 
 	if (dev->mmio) {
-		i8254 = comedi_8254_mm_init(dev->mmio + offset,
-					    0, I8254_IO8, regshift);
+		i8254 = comedi_8254_mm_alloc(dev->mmio + offset,
+					     0, I8254_IO8, regshift);
 	} else {
-		i8254 = comedi_8254_init(dev->iobase + offset,
-					 0, I8254_IO8, regshift);
+		i8254 = comedi_8254_io_alloc(dev->iobase + offset,
+					     0, I8254_IO8, regshift);
 	}
-	if (!i8254)
-		return -ENOMEM;
+	if (IS_ERR(i8254))
+		return PTR_ERR(i8254);
 
 	comedi_8254_subdevice_init(s, i8254);
 
@@ -779,6 +833,12 @@ int amplc_dio200_common_attach(struct comedi_device *dev, unsigned int irq,
 	unsigned int n;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_HAS_IOPORT) && !dev->mmio) {
+		dev_err(dev->class_dev,
+			"error! need I/O port support\n");
+		return -ENXIO;
+	}
+
 	ret = comedi_alloc_subdevices(dev, board->n_subdevs);
 	if (ret)
 		return ret;
diff --git a/drivers/comedi/drivers/amplc_dio200_pci.c b/drivers/comedi/drivers/amplc_dio200_pci.c
index 527994d82a..cb5b328a28 100644
--- a/drivers/comedi/drivers/amplc_dio200_pci.c
+++ b/drivers/comedi/drivers/amplc_dio200_pci.c
@@ -223,14 +223,17 @@
  */
 
 enum dio200_pci_model {
+#ifdef CONFIG_HAS_IOPORT
 	pci215_model,
 	pci272_model,
+#endif /* CONFIG_HAS_IOPORT */
 	pcie215_model,
 	pcie236_model,
 	pcie296_model
 };
 
 static const struct dio200_board dio200_pci_boards[] = {
+#ifdef CONFIG_HAS_IOPORT
 	[pci215_model] = {
 		.name		= "pci215",
 		.mainbar	= 2,
@@ -252,6 +255,7 @@ static const struct dio200_board dio200_pci_boards[] = {
 		.sdinfo		= { 0x00, 0x08, 0x10, 0x3f },
 		.has_int_sce	= true,
 	},
+#endif /* CONFIG_HAS_IOPORT */
 	[pcie215_model] = {
 		.name		= "pcie215",
 		.mainbar	= 1,
@@ -364,8 +368,12 @@ static int dio200_pci_auto_attach(struct comedi_device *dev,
 				"error! cannot remap registers\n");
 			return -ENOMEM;
 		}
-	} else {
+	} else if (IS_ENABLED(CONFIG_HAS_IOPORT)) {
 		dev->iobase = pci_resource_start(pci_dev, bar);
+	} else {
+		dev_err(dev->class_dev,
+			"error! need I/O port support\n");
+		return -ENXIO;
 	}
 
 	if (board->is_pcie) {
@@ -385,8 +393,10 @@ static struct comedi_driver dio200_pci_comedi_driver = {
 };
 
 static const struct pci_device_id dio200_pci_table[] = {
+#ifdef CONFIG_HAS_IOPORT
 	{ PCI_VDEVICE(AMPLICON, 0x000b), pci215_model },
 	{ PCI_VDEVICE(AMPLICON, 0x000a), pci272_model },
+#endif /* CONFIG_HAS_IOPORT */
 	{ PCI_VDEVICE(AMPLICON, 0x0011), pcie236_model },
 	{ PCI_VDEVICE(AMPLICON, 0x0012), pcie215_model },
 	{ PCI_VDEVICE(AMPLICON, 0x0014), pcie296_model },
diff --git a/drivers/comedi/drivers/amplc_pc236_common.c b/drivers/comedi/drivers/amplc_pc236_common.c
index 9f4f89b1ef..326ca72c24 100644
--- a/drivers/comedi/drivers/amplc_pc236_common.c
+++ b/drivers/comedi/drivers/amplc_pc236_common.c
@@ -147,7 +147,7 @@ int amplc_pc236_common_attach(struct comedi_device *dev, unsigned long iobase,
 
 	s = &dev->subdevices[0];
 	/* digital i/o subdevice (8255) */
-	ret = subdev_8255_init(dev, s, NULL, 0x00);
+	ret = subdev_8255_io_init(dev, s, 0x00);
 	if (ret)
 		return ret;
 
diff --git a/drivers/comedi/drivers/amplc_pci224.c b/drivers/comedi/drivers/amplc_pci224.c
index 5a04e55dae..1373637c2c 100644
--- a/drivers/comedi/drivers/amplc_pci224.c
+++ b/drivers/comedi/drivers/amplc_pci224.c
@@ -1051,10 +1051,10 @@ pci224_auto_attach(struct comedi_device *dev, unsigned long context_model)
 	outw(devpriv->daccon | PCI224_DACCON_FIFORESET,
 	     dev->iobase + PCI224_DACCON);
 
-	dev->pacer = comedi_8254_init(devpriv->iobase1 + PCI224_Z2_BASE,
-				      I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(devpriv->iobase1 + PCI224_Z2_BASE,
+					  I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 1);
 	if (ret)
diff --git a/drivers/comedi/drivers/amplc_pci230.c b/drivers/comedi/drivers/amplc_pci230.c
index 92ba8b8c01..c74209c2e8 100644
--- a/drivers/comedi/drivers/amplc_pci230.c
+++ b/drivers/comedi/drivers/amplc_pci230.c
@@ -2475,10 +2475,10 @@ static int pci230_auto_attach(struct comedi_device *dev,
 			dev->irq = pci_dev->irq;
 	}
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCI230_Z2_CT_BASE,
-				      0, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCI230_Z2_CT_BASE,
+					  0, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	rc = comedi_alloc_subdevices(dev, 3);
 	if (rc)
@@ -2529,7 +2529,7 @@ static int pci230_auto_attach(struct comedi_device *dev,
 	s = &dev->subdevices[2];
 	/* digital i/o subdevice */
 	if (board->have_dio) {
-		rc = subdev_8255_init(dev, s, NULL, PCI230_PPI_X_BASE);
+		rc = subdev_8255_io_init(dev, s, PCI230_PPI_X_BASE);
 		if (rc)
 			return rc;
 	} else {
diff --git a/drivers/comedi/drivers/cb_das16_cs.c b/drivers/comedi/drivers/cb_das16_cs.c
index 8e0d2fa5f9..306208a069 100644
--- a/drivers/comedi/drivers/cb_das16_cs.c
+++ b/drivers/comedi/drivers/cb_das16_cs.c
@@ -363,10 +363,10 @@ static int das16cs_auto_attach(struct comedi_device *dev,
 	if (!devpriv)
 		return -ENOMEM;
 
-	dev->pacer = comedi_8254_init(dev->iobase + DAS16CS_TIMER_BASE,
-				      I8254_OSC_BASE_10MHZ, I8254_IO16, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + DAS16CS_TIMER_BASE,
+					  I8254_OSC_BASE_10MHZ, I8254_IO16, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
diff --git a/drivers/comedi/drivers/cb_pcidas.c b/drivers/comedi/drivers/cb_pcidas.c
index 0c7576b967..8bb9b06238 100644
--- a/drivers/comedi/drivers/cb_pcidas.c
+++ b/drivers/comedi/drivers/cb_pcidas.c
@@ -1288,16 +1288,16 @@ static int cb_pcidas_auto_attach(struct comedi_device *dev,
 	}
 	dev->irq = pcidev->irq;
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCIDAS_AI_8254_BASE,
-				      I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCIDAS_AI_8254_BASE,
+					  I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
-	devpriv->ao_pacer = comedi_8254_init(dev->iobase + PCIDAS_AO_8254_BASE,
-					     I8254_OSC_BASE_10MHZ,
-					     I8254_IO8, 0);
-	if (!devpriv->ao_pacer)
-		return -ENOMEM;
+	devpriv->ao_pacer =
+	    comedi_8254_io_alloc(dev->iobase + PCIDAS_AO_8254_BASE,
+				 I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
+	if (IS_ERR(devpriv->ao_pacer))
+		return PTR_ERR(devpriv->ao_pacer);
 
 	ret = comedi_alloc_subdevices(dev, 7);
 	if (ret)
@@ -1352,7 +1352,7 @@ static int cb_pcidas_auto_attach(struct comedi_device *dev,
 
 	/* 8255 */
 	s = &dev->subdevices[2];
-	ret = subdev_8255_init(dev, s, NULL, PCIDAS_8255_BASE);
+	ret = subdev_8255_io_init(dev, s, PCIDAS_8255_BASE);
 	if (ret)
 		return ret;
 
@@ -1453,7 +1453,8 @@ static void cb_pcidas_detach(struct comedi_device *dev)
 		if (devpriv->amcc)
 			outl(INTCSR_INBOX_INTR_STATUS,
 			     devpriv->amcc + AMCC_OP_REG_INTCSR);
-		kfree(devpriv->ao_pacer);
+		if (!IS_ERR(devpriv->ao_pacer))
+			kfree(devpriv->ao_pacer);
 	}
 	comedi_pci_detach(dev);
 }
diff --git a/drivers/comedi/drivers/cb_pcidas64.c b/drivers/comedi/drivers/cb_pcidas64.c
index ca6038a25f..ff19fc3859 100644
--- a/drivers/comedi/drivers/cb_pcidas64.c
+++ b/drivers/comedi/drivers/cb_pcidas64.c
@@ -3877,11 +3877,10 @@ static int setup_subdevices(struct comedi_device *dev)
 	s = &dev->subdevices[4];
 	if (board->has_8255) {
 		if (board->layout == LAYOUT_4020) {
-			ret = subdev_8255_init(dev, s, dio_callback_4020,
-					       I8255_4020_REG);
+			ret = subdev_8255_cb_init(dev, s, dio_callback_4020,
+						  I8255_4020_REG);
 		} else {
-			ret = subdev_8255_mm_init(dev, s, NULL,
-						  DIO_8255_OFFSET);
+			ret = subdev_8255_mm_init(dev, s, DIO_8255_OFFSET);
 		}
 		if (ret)
 			return ret;
diff --git a/drivers/comedi/drivers/cb_pcidda.c b/drivers/comedi/drivers/cb_pcidda.c
index c52204a6bd..c353d0f87d 100644
--- a/drivers/comedi/drivers/cb_pcidda.c
+++ b/drivers/comedi/drivers/cb_pcidda.c
@@ -365,7 +365,7 @@ static int cb_pcidda_auto_attach(struct comedi_device *dev,
 	/* two 8255 digital io subdevices */
 	for (i = 0; i < 2; i++) {
 		s = &dev->subdevices[1 + i];
-		ret = subdev_8255_init(dev, s, NULL, i * I8255_SIZE);
+		ret = subdev_8255_io_init(dev, s, i * I8255_SIZE);
 		if (ret)
 			return ret;
 	}
diff --git a/drivers/comedi/drivers/cb_pcimdas.c b/drivers/comedi/drivers/cb_pcimdas.c
index 8bdb00774f..641c30df39 100644
--- a/drivers/comedi/drivers/cb_pcimdas.c
+++ b/drivers/comedi/drivers/cb_pcimdas.c
@@ -364,11 +364,11 @@ static int cb_pcimdas_auto_attach(struct comedi_device *dev,
 	devpriv->BADR3 = pci_resource_start(pcidev, 3);
 	dev->iobase = pci_resource_start(pcidev, 4);
 
-	dev->pacer = comedi_8254_init(devpriv->BADR3 + PCIMDAS_8254_BASE,
-				      cb_pcimdas_pacer_clk(dev),
-				      I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(devpriv->BADR3 + PCIMDAS_8254_BASE,
+					  cb_pcimdas_pacer_clk(dev),
+					  I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 6);
 	if (ret)
@@ -405,7 +405,7 @@ static int cb_pcimdas_auto_attach(struct comedi_device *dev,
 
 	/* Digital I/O subdevice */
 	s = &dev->subdevices[2];
-	ret = subdev_8255_init(dev, s, NULL, PCIMDAS_8255_BASE);
+	ret = subdev_8255_io_init(dev, s, PCIMDAS_8255_BASE);
 	if (ret)
 		return ret;
 
diff --git a/drivers/comedi/drivers/cb_pcimdda.c b/drivers/comedi/drivers/cb_pcimdda.c
index bf8093a103..541b5742bb 100644
--- a/drivers/comedi/drivers/cb_pcimdda.c
+++ b/drivers/comedi/drivers/cb_pcimdda.c
@@ -154,7 +154,7 @@ static int cb_pcimdda_auto_attach(struct comedi_device *dev,
 
 	s = &dev->subdevices[1];
 	/* digital i/o subdevice */
-	return subdev_8255_init(dev, s, NULL, PCIMDDA_8255_BASE_REG);
+	return subdev_8255_io_init(dev, s, PCIMDDA_8255_BASE_REG);
 }
 
 static struct comedi_driver cb_pcimdda_driver = {
diff --git a/drivers/comedi/drivers/comedi_8254.c b/drivers/comedi/drivers/comedi_8254.c
index b4185c1b26..6beca2a6d6 100644
--- a/drivers/comedi/drivers/comedi_8254.c
+++ b/drivers/comedi/drivers/comedi_8254.c
@@ -24,14 +24,17 @@
  *
  * This module provides the following basic functions:
  *
- * comedi_8254_init() / comedi_8254_mm_init()
+ * comedi_8254_io_alloc() / comedi_8254_mm_alloc()
  *	Initializes this module to access the 8254 registers. The _mm version
- *	sets up the module for MMIO register access the other for PIO access.
- *	The pointer returned from these functions is normally stored in the
- *	comedi_device dev->pacer and will be freed by the comedi core during
- *	the driver (*detach). If a driver has multiple 8254 devices, they need
- *	to be stored in the drivers private data and freed when the driver is
- *	detached.
+ *	sets up the module for MMIO register access; the _io version sets it
+ *	up for PIO access.  These functions return a pointer to a struct
+ *	comedi_8254 on success, or an ERR_PTR value on failure.  The pointer
+ *	returned from these functions is normally stored in the comedi_device
+ *	dev->pacer and will be freed by the comedi core during the driver
+ *	(*detach). If a driver has multiple 8254 devices, they need to be
+ *	stored in the drivers private data and freed when the driver is
+ *	detached.  If the ERR_PTR value is stored, code should check the
+ *	pointer value with !IS_ERR(pointer) before freeing.
  *
  *	NOTE: The counters are reset by setting them to I8254_MODE0 as part of
  *	this initialization.
@@ -119,63 +122,105 @@
 #include <linux/comedi/comedidev.h>
 #include <linux/comedi/comedi_8254.h>
 
-static unsigned int __i8254_read(struct comedi_8254 *i8254, unsigned int reg)
+#ifdef CONFIG_HAS_IOPORT
+
+static unsigned int i8254_io8_cb(struct comedi_8254 *i8254, int dir,
+				unsigned int reg, unsigned int val)
 {
-	unsigned int reg_offset = (reg * i8254->iosize) << i8254->regshift;
-	unsigned int val;
+	unsigned long iobase = i8254->context;
+	unsigned int reg_offset = (reg * I8254_IO8) << i8254->regshift;
 
-	switch (i8254->iosize) {
-	default:
-	case I8254_IO8:
-		if (i8254->mmio)
-			val = readb(i8254->mmio + reg_offset);
-		else
-			val = inb(i8254->iobase + reg_offset);
-		break;
-	case I8254_IO16:
-		if (i8254->mmio)
-			val = readw(i8254->mmio + reg_offset);
-		else
-			val = inw(i8254->iobase + reg_offset);
-		break;
-	case I8254_IO32:
-		if (i8254->mmio)
-			val = readl(i8254->mmio + reg_offset);
-		else
-			val = inl(i8254->iobase + reg_offset);
-		break;
+	if (dir) {
+		outb(val, iobase + reg_offset);
+		return 0;
+	} else {
+		return inb(iobase + reg_offset);
 	}
-	return val & 0xff;
 }
 
-static void __i8254_write(struct comedi_8254 *i8254,
-			  unsigned int val, unsigned int reg)
+static unsigned int i8254_io16_cb(struct comedi_8254 *i8254, int dir,
+				  unsigned int reg, unsigned int val)
 {
-	unsigned int reg_offset = (reg * i8254->iosize) << i8254->regshift;
+	unsigned long iobase = i8254->context;
+	unsigned int reg_offset = (reg * I8254_IO16) << i8254->regshift;
 
-	switch (i8254->iosize) {
-	default:
-	case I8254_IO8:
-		if (i8254->mmio)
-			writeb(val, i8254->mmio + reg_offset);
-		else
-			outb(val, i8254->iobase + reg_offset);
-		break;
-	case I8254_IO16:
-		if (i8254->mmio)
-			writew(val, i8254->mmio + reg_offset);
-		else
-			outw(val, i8254->iobase + reg_offset);
-		break;
-	case I8254_IO32:
-		if (i8254->mmio)
-			writel(val, i8254->mmio + reg_offset);
-		else
-			outl(val, i8254->iobase + reg_offset);
-		break;
+	if (dir) {
+		outw(val, iobase + reg_offset);
+		return 0;
+	} else {
+		return inw(iobase + reg_offset);
 	}
 }
 
+static unsigned int i8254_io32_cb(struct comedi_8254 *i8254, int dir,
+				  unsigned int reg, unsigned int val)
+{
+	unsigned long iobase = i8254->context;
+	unsigned int reg_offset = (reg * I8254_IO32) << i8254->regshift;
+
+	if (dir) {
+		outl(val, iobase + reg_offset);
+		return 0;
+	} else {
+		return inl(iobase + reg_offset);
+	}
+}
+
+#endif	/* CONFIG_HAS_IOPORT */
+
+static unsigned int i8254_mmio8_cb(struct comedi_8254 *i8254, int dir,
+				   unsigned int reg, unsigned int val)
+{
+	void __iomem *mmiobase = (void __iomem *)i8254->context;
+	unsigned int reg_offset = (reg * I8254_IO8) << i8254->regshift;
+
+	if (dir) {
+		writeb(val, mmiobase + reg_offset);
+		return 0;
+	} else {
+		return readb(mmiobase + reg_offset);
+	}
+}
+
+static unsigned int i8254_mmio16_cb(struct comedi_8254 *i8254, int dir,
+				    unsigned int reg, unsigned int val)
+{
+	void __iomem *mmiobase = (void __iomem *)i8254->context;
+	unsigned int reg_offset = (reg * I8254_IO16) << i8254->regshift;
+
+	if (dir) {
+		writew(val, mmiobase + reg_offset);
+		return 0;
+	} else {
+		return readw(mmiobase + reg_offset);
+	}
+}
+
+static unsigned int i8254_mmio32_cb(struct comedi_8254 *i8254, int dir,
+				    unsigned int reg, unsigned int val)
+{
+	void __iomem *mmiobase = (void __iomem *)i8254->context;
+	unsigned int reg_offset = (reg * I8254_IO32) << i8254->regshift;
+
+	if (dir) {
+		writel(val, mmiobase + reg_offset);
+		return 0;
+	} else {
+		return readl(mmiobase + reg_offset);
+	}
+}
+
+static unsigned int __i8254_read(struct comedi_8254 *i8254, unsigned int reg)
+{
+	return 0xff & i8254->iocb(i8254, 0, reg, 0);
+}
+
+static void __i8254_write(struct comedi_8254 *i8254,
+			  unsigned int val, unsigned int reg)
+{
+	i8254->iocb(i8254, 1, reg, val);
+}
+
 /**
  * comedi_8254_status - return the status of a counter
  * @i8254:	comedi_8254 struct for the timer
@@ -571,8 +616,8 @@ void comedi_8254_subdevice_init(struct comedi_subdevice *s,
 }
 EXPORT_SYMBOL_GPL(comedi_8254_subdevice_init);
 
-static struct comedi_8254 *__i8254_init(unsigned long iobase,
-					void __iomem *mmio,
+static struct comedi_8254 *__i8254_init(comedi_8254_iocb_fn *iocb,
+					unsigned long context,
 					unsigned int osc_base,
 					unsigned int iosize,
 					unsigned int regshift)
@@ -583,14 +628,17 @@ static struct comedi_8254 *__i8254_init(unsigned long iobase,
 	/* sanity check that the iosize is valid */
 	if (!(iosize == I8254_IO8 || iosize == I8254_IO16 ||
 	      iosize == I8254_IO32))
-		return NULL;
+		return ERR_PTR(-EINVAL);
+
+	if (!iocb)
+		return ERR_PTR(-EINVAL);
 
 	i8254 = kzalloc(sizeof(*i8254), GFP_KERNEL);
 	if (!i8254)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
-	i8254->iobase	= iobase;
-	i8254->mmio	= mmio;
+	i8254->iocb	= iocb;
+	i8254->context	= context;
 	i8254->iosize	= iosize;
 	i8254->regshift	= regshift;
 
@@ -604,39 +652,77 @@ static struct comedi_8254 *__i8254_init(unsigned long iobase,
 	return i8254;
 }
 
+#ifdef CONFIG_HAS_IOPORT
+
 /**
- * comedi_8254_init - allocate and initialize the 8254 device for pio access
+ * comedi_8254_io_alloc - allocate and initialize the 8254 device for pio access
  * @iobase:	port I/O base address
  * @osc_base:	base time of the counter in ns
  *		OPTIONAL - only used by comedi_8254_cascade_ns_to_timer()
  * @iosize:	I/O register size
  * @regshift:	register gap shift
+ *
+ * Return: A pointer to a struct comedi_8254 or an ERR_PTR value.
  */
-struct comedi_8254 *comedi_8254_init(unsigned long iobase,
-				     unsigned int osc_base,
-				     unsigned int iosize,
-				     unsigned int regshift)
+struct comedi_8254 *comedi_8254_io_alloc(unsigned long iobase,
+					 unsigned int osc_base,
+					 unsigned int iosize,
+					 unsigned int regshift)
 {
-	return __i8254_init(iobase, NULL, osc_base, iosize, regshift);
+	comedi_8254_iocb_fn *iocb;
+
+	switch (iosize) {
+	case I8254_IO8:
+		iocb = i8254_io8_cb;
+		break;
+	case I8254_IO16:
+		iocb = i8254_io16_cb;
+		break;
+	case I8254_IO32:
+		iocb = i8254_io32_cb;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+	return __i8254_init(iocb, iobase, osc_base, iosize, regshift);
 }
-EXPORT_SYMBOL_GPL(comedi_8254_init);
+EXPORT_SYMBOL_GPL(comedi_8254_io_alloc);
+
+#endif	/* CONFIG_HAS_IOPORT */
 
 /**
- * comedi_8254_mm_init - allocate and initialize the 8254 device for mmio access
+ * comedi_8254_mm_alloc - allocate and initialize the 8254 device for mmio access
  * @mmio:	memory mapped I/O base address
  * @osc_base:	base time of the counter in ns
  *		OPTIONAL - only used by comedi_8254_cascade_ns_to_timer()
  * @iosize:	I/O register size
  * @regshift:	register gap shift
+ *
+ * Return: A pointer to a struct comedi_8254 or an ERR_PTR value.
  */
-struct comedi_8254 *comedi_8254_mm_init(void __iomem *mmio,
-					unsigned int osc_base,
-					unsigned int iosize,
-					unsigned int regshift)
+struct comedi_8254 *comedi_8254_mm_alloc(void __iomem *mmio,
+					 unsigned int osc_base,
+					 unsigned int iosize,
+					 unsigned int regshift)
 {
-	return __i8254_init(0, mmio, osc_base, iosize, regshift);
+	comedi_8254_iocb_fn *iocb;
+
+	switch (iosize) {
+	case I8254_IO8:
+		iocb = i8254_mmio8_cb;
+		break;
+	case I8254_IO16:
+		iocb = i8254_mmio16_cb;
+		break;
+	case I8254_IO32:
+		iocb = i8254_mmio32_cb;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+	return __i8254_init(iocb, (unsigned long)mmio, osc_base, iosize, regshift);
 }
-EXPORT_SYMBOL_GPL(comedi_8254_mm_init);
+EXPORT_SYMBOL_GPL(comedi_8254_mm_alloc);
 
 static int __init comedi_8254_module_init(void)
 {
diff --git a/drivers/comedi/drivers/comedi_8255.c b/drivers/comedi/drivers/comedi_8255.c
index 5562b9cd0a..e4974b5083 100644
--- a/drivers/comedi/drivers/comedi_8255.c
+++ b/drivers/comedi/drivers/comedi_8255.c
@@ -33,11 +33,13 @@
 #include <linux/comedi/comedi_8255.h>
 
 struct subdev_8255_private {
-	unsigned long regbase;
+	unsigned long context;
 	int (*io)(struct comedi_device *dev, int dir, int port, int data,
-		  unsigned long regbase);
+		  unsigned long context);
 };
 
+#ifdef CONFIG_HAS_IOPORT
+
 static int subdev_8255_io(struct comedi_device *dev,
 			  int dir, int port, int data, unsigned long regbase)
 {
@@ -48,6 +50,8 @@ static int subdev_8255_io(struct comedi_device *dev,
 	return inb(dev->iobase + regbase + port);
 }
 
+#endif /* CONFIG_HAS_IOPORT */
+
 static int subdev_8255_mmio(struct comedi_device *dev,
 			    int dir, int port, int data, unsigned long regbase)
 {
@@ -64,7 +68,7 @@ static int subdev_8255_insn(struct comedi_device *dev,
 			    unsigned int *data)
 {
 	struct subdev_8255_private *spriv = s->private;
-	unsigned long regbase = spriv->regbase;
+	unsigned long context = spriv->context;
 	unsigned int mask;
 	unsigned int v;
 
@@ -72,18 +76,18 @@ static int subdev_8255_insn(struct comedi_device *dev,
 	if (mask) {
 		if (mask & 0xff)
 			spriv->io(dev, 1, I8255_DATA_A_REG,
-				  s->state & 0xff, regbase);
+				  s->state & 0xff, context);
 		if (mask & 0xff00)
 			spriv->io(dev, 1, I8255_DATA_B_REG,
-				  (s->state >> 8) & 0xff, regbase);
+				  (s->state >> 8) & 0xff, context);
 		if (mask & 0xff0000)
 			spriv->io(dev, 1, I8255_DATA_C_REG,
-				  (s->state >> 16) & 0xff, regbase);
+				  (s->state >> 16) & 0xff, context);
 	}
 
-	v = spriv->io(dev, 0, I8255_DATA_A_REG, 0, regbase);
-	v |= (spriv->io(dev, 0, I8255_DATA_B_REG, 0, regbase) << 8);
-	v |= (spriv->io(dev, 0, I8255_DATA_C_REG, 0, regbase) << 16);
+	v = spriv->io(dev, 0, I8255_DATA_A_REG, 0, context);
+	v |= (spriv->io(dev, 0, I8255_DATA_B_REG, 0, context) << 8);
+	v |= (spriv->io(dev, 0, I8255_DATA_C_REG, 0, context) << 16);
 
 	data[1] = v;
 
@@ -94,7 +98,7 @@ static void subdev_8255_do_config(struct comedi_device *dev,
 				  struct comedi_subdevice *s)
 {
 	struct subdev_8255_private *spriv = s->private;
-	unsigned long regbase = spriv->regbase;
+	unsigned long context = spriv->context;
 	int config;
 
 	config = I8255_CTRL_CW;
@@ -108,7 +112,7 @@ static void subdev_8255_do_config(struct comedi_device *dev,
 	if (!(s->io_bits & 0xf00000))
 		config |= I8255_CTRL_C_HI_IO;
 
-	spriv->io(dev, 1, I8255_CTRL_REG, config, regbase);
+	spriv->io(dev, 1, I8255_CTRL_REG, config, context);
 }
 
 static int subdev_8255_insn_config(struct comedi_device *dev,
@@ -142,23 +146,19 @@ static int __subdev_8255_init(struct comedi_device *dev,
 			      struct comedi_subdevice *s,
 			      int (*io)(struct comedi_device *dev,
 					int dir, int port, int data,
-					unsigned long regbase),
-			      unsigned long regbase,
-			      bool is_mmio)
+					unsigned long context),
+			      unsigned long context)
 {
 	struct subdev_8255_private *spriv;
 
+	if (!io)
+		return -EINVAL;
+
 	spriv = comedi_alloc_spriv(s, sizeof(*spriv));
 	if (!spriv)
 		return -ENOMEM;
 
-	if (io)
-		spriv->io = io;
-	else if (is_mmio)
-		spriv->io = subdev_8255_mmio;
-	else
-		spriv->io = subdev_8255_io;
-	spriv->regbase	= regbase;
+	spriv->context = context;
 
 	s->type		= COMEDI_SUBD_DIO;
 	s->subdev_flags	= SDF_READABLE | SDF_WRITABLE;
@@ -173,89 +173,88 @@ static int __subdev_8255_init(struct comedi_device *dev,
 	return 0;
 }
 
+#ifdef CONFIG_HAS_IOPORT
+
 /**
- * subdev_8255_init - initialize DIO subdevice for driving I/O mapped 8255
+ * subdev_8255_io_init - initialize DIO subdevice for driving I/O mapped 8255
  * @dev: comedi device owning subdevice
  * @s: comedi subdevice to initialize
- * @io: (optional) register I/O call-back function
- * @regbase: offset of 8255 registers from dev->iobase, or call-back context
+ * @regbase: offset of 8255 registers from dev->iobase
  *
  * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
  *
- * If the optional I/O call-back function is provided, its prototype is of
- * the following form:
- *
- *   int my_8255_callback(struct comedi_device *dev, int dir, int port,
- *                        int data, unsigned long regbase);
- *
- * where 'dev', and 'regbase' match the values passed to this function,
- * 'port' is the 8255 port number 0 to 3 (including the control port), 'dir'
- * is the direction (0 for read, 1 for write) and 'data' is the value to be
- * written.  It should return 0 if writing or the value read if reading.
- *
- * If the optional I/O call-back function is not provided, an internal
- * call-back function is used which uses consecutive I/O port addresses
- * starting at dev->iobase + regbase.
- *
  * Return: -ENOMEM if failed to allocate memory, zero on success.
  */
-int subdev_8255_init(struct comedi_device *dev, struct comedi_subdevice *s,
-		     int (*io)(struct comedi_device *dev, int dir, int port,
-			       int data, unsigned long regbase),
+int subdev_8255_io_init(struct comedi_device *dev, struct comedi_subdevice *s,
 		     unsigned long regbase)
 {
-	return __subdev_8255_init(dev, s, io, regbase, false);
+	return __subdev_8255_init(dev, s, subdev_8255_io, regbase);
 }
-EXPORT_SYMBOL_GPL(subdev_8255_init);
+EXPORT_SYMBOL_GPL(subdev_8255_io_init);
+
+#endif	/* CONFIG_HAS_IOPORT */
 
 /**
  * subdev_8255_mm_init - initialize DIO subdevice for driving mmio-mapped 8255
  * @dev: comedi device owning subdevice
  * @s: comedi subdevice to initialize
- * @io: (optional) register I/O call-back function
- * @regbase: offset of 8255 registers from dev->mmio, or call-back context
+ * @regbase: offset of 8255 registers from dev->mmio
  *
  * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
  *
- * If the optional I/O call-back function is provided, its prototype is of
- * the following form:
+ * Return: -ENOMEM if failed to allocate memory, zero on success.
+ */
+int subdev_8255_mm_init(struct comedi_device *dev, struct comedi_subdevice *s,
+			unsigned long regbase)
+{
+	return __subdev_8255_init(dev, s, subdev_8255_mmio, regbase);
+}
+EXPORT_SYMBOL_GPL(subdev_8255_mm_init);
+
+/**
+ * subdev_8255_cb_init - initialize DIO subdevice for driving callback-mapped 8255
+ * @dev: comedi device owning subdevice
+ * @s: comedi subdevice to initialize
+ * @io: register I/O call-back function
+ * @context: call-back context
+ *
+ * Initializes a comedi subdevice as a DIO subdevice driving an 8255 chip.
+ *
+ * The prototype of the I/O call-back function is of the following form:
  *
  *   int my_8255_callback(struct comedi_device *dev, int dir, int port,
- *                        int data, unsigned long regbase);
+ *                        int data, unsigned long context);
  *
- * where 'dev', and 'regbase' match the values passed to this function,
+ * where 'dev', and 'context' match the values passed to this function,
  * 'port' is the 8255 port number 0 to 3 (including the control port), 'dir'
  * is the direction (0 for read, 1 for write) and 'data' is the value to be
  * written.  It should return 0 if writing or the value read if reading.
  *
- * If the optional I/O call-back function is not provided, an internal
- * call-back function is used which uses consecutive MMIO virtual addresses
- * starting at dev->mmio + regbase.
  *
  * Return: -ENOMEM if failed to allocate memory, zero on success.
  */
-int subdev_8255_mm_init(struct comedi_device *dev, struct comedi_subdevice *s,
+int subdev_8255_cb_init(struct comedi_device *dev, struct comedi_subdevice *s,
 			int (*io)(struct comedi_device *dev, int dir, int port,
-				  int data, unsigned long regbase),
-			unsigned long regbase)
+				  int data, unsigned long context),
+			unsigned long context)
 {
-	return __subdev_8255_init(dev, s, io, regbase, true);
+	return __subdev_8255_init(dev, s, io, context);
 }
-EXPORT_SYMBOL_GPL(subdev_8255_mm_init);
+EXPORT_SYMBOL_GPL(subdev_8255_cb_init);
 
 /**
  * subdev_8255_regbase - get offset of 8255 registers or call-back context
  * @s: comedi subdevice
  *
- * Returns the 'regbase' parameter that was previously passed to
- * subdev_8255_init() or subdev_8255_mm_init() to set up the subdevice.
- * Only valid if the subdevice was set up successfully.
+ * Returns the 'regbase' or 'context' parameter that was previously passed to
+ * subdev_8255_io_init(), subdev_8255_mm_init(), or subdev_8255_cb_init() to
+ * set up the subdevice.  Only valid if the subdevice was set up successfully.
  */
 unsigned long subdev_8255_regbase(struct comedi_subdevice *s)
 {
 	struct subdev_8255_private *spriv = s->private;
 
-	return spriv->regbase;
+	return spriv->context;
 }
 EXPORT_SYMBOL_GPL(subdev_8255_regbase);
 
diff --git a/drivers/comedi/drivers/daqboard2000.c b/drivers/comedi/drivers/daqboard2000.c
index c0a4e1b06f..897bf46b95 100644
--- a/drivers/comedi/drivers/daqboard2000.c
+++ b/drivers/comedi/drivers/daqboard2000.c
@@ -738,8 +738,8 @@ static int db2k_auto_attach(struct comedi_device *dev, unsigned long context)
 		return result;
 
 	s = &dev->subdevices[2];
-	return subdev_8255_init(dev, s, db2k_8255_cb,
-				DB2K_REG_DIO_P2_EXP_IO_8_BIT);
+	return subdev_8255_cb_init(dev, s, db2k_8255_cb,
+				   DB2K_REG_DIO_P2_EXP_IO_8_BIT);
 }
 
 static void db2k_detach(struct comedi_device *dev)
diff --git a/drivers/comedi/drivers/das08.c b/drivers/comedi/drivers/das08.c
index f8ab3af2e3..5d5b9174f8 100644
--- a/drivers/comedi/drivers/das08.c
+++ b/drivers/comedi/drivers/das08.c
@@ -429,7 +429,7 @@ int das08_common_attach(struct comedi_device *dev, unsigned long iobase)
 	s = &dev->subdevices[4];
 	/* 8255 */
 	if (board->i8255_offset != 0) {
-		ret = subdev_8255_init(dev, s, NULL, board->i8255_offset);
+		ret = subdev_8255_io_init(dev, s, board->i8255_offset);
 		if (ret)
 			return ret;
 	} else {
@@ -439,10 +439,11 @@ int das08_common_attach(struct comedi_device *dev, unsigned long iobase)
 	/* Counter subdevice (8254) */
 	s = &dev->subdevices[5];
 	if (board->i8254_offset) {
-		dev->pacer = comedi_8254_init(dev->iobase + board->i8254_offset,
-					      0, I8254_IO8, 0);
-		if (!dev->pacer)
-			return -ENOMEM;
+		dev->pacer =
+		    comedi_8254_io_alloc(dev->iobase + board->i8254_offset,
+					 0, I8254_IO8, 0);
+		if (IS_ERR(dev->pacer))
+			return PTR_ERR(dev->pacer);
 
 		comedi_8254_subdevice_init(s, dev->pacer);
 	} else {
diff --git a/drivers/comedi/drivers/das16.c b/drivers/comedi/drivers/das16.c
index 728dc02156..4ed56a0215 100644
--- a/drivers/comedi/drivers/das16.c
+++ b/drivers/comedi/drivers/das16.c
@@ -1067,10 +1067,10 @@ static int das16_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 			osc_base = I8254_OSC_BASE_1MHZ / it->options[3];
 	}
 
-	dev->pacer = comedi_8254_init(dev->iobase + DAS16_TIMER_BASE_REG,
-				      osc_base, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + DAS16_TIMER_BASE_REG,
+					  osc_base, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	das16_alloc_dma(dev, it->options[2]);
 
@@ -1145,7 +1145,7 @@ static int das16_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	/* 8255 Digital I/O subdevice */
 	if (board->has_8255) {
 		s = &dev->subdevices[4];
-		ret = subdev_8255_init(dev, s, NULL, board->i8255_offset);
+		ret = subdev_8255_io_init(dev, s, board->i8255_offset);
 		if (ret)
 			return ret;
 	}
diff --git a/drivers/comedi/drivers/das16m1.c b/drivers/comedi/drivers/das16m1.c
index 275effb777..b8ea737ad3 100644
--- a/drivers/comedi/drivers/das16m1.c
+++ b/drivers/comedi/drivers/das16m1.c
@@ -529,15 +529,16 @@ static int das16m1_attach(struct comedi_device *dev,
 			dev->irq = it->options[1];
 	}
 
-	dev->pacer = comedi_8254_init(dev->iobase + DAS16M1_8254_IOBASE2,
-				      I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + DAS16M1_8254_IOBASE2,
+					  I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
-	devpriv->counter = comedi_8254_init(dev->iobase + DAS16M1_8254_IOBASE1,
-					    0, I8254_IO8, 0);
-	if (!devpriv->counter)
-		return -ENOMEM;
+	devpriv->counter =
+	    comedi_8254_io_alloc(dev->iobase + DAS16M1_8254_IOBASE1,
+				 0, I8254_IO8, 0);
+	if (IS_ERR(devpriv->counter))
+		return PTR_ERR(devpriv->counter);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
@@ -582,7 +583,7 @@ static int das16m1_attach(struct comedi_device *dev,
 
 	/* Digital I/O subdevice (8255) */
 	s = &dev->subdevices[3];
-	ret = subdev_8255_init(dev, s, NULL, DAS16M1_8255_IOBASE);
+	ret = subdev_8255_io_init(dev, s, DAS16M1_8255_IOBASE);
 	if (ret)
 		return ret;
 
@@ -603,7 +604,8 @@ static void das16m1_detach(struct comedi_device *dev)
 	if (devpriv) {
 		if (devpriv->extra_iobase)
 			release_region(devpriv->extra_iobase, DAS16M1_SIZE2);
-		kfree(devpriv->counter);
+		if (!IS_ERR(devpriv->counter))
+			kfree(devpriv->counter);
 	}
 	comedi_legacy_detach(dev);
 }
diff --git a/drivers/comedi/drivers/das1800.c b/drivers/comedi/drivers/das1800.c
index f09608c0f4..7117c67aee 100644
--- a/drivers/comedi/drivers/das1800.c
+++ b/drivers/comedi/drivers/das1800.c
@@ -1233,10 +1233,10 @@ static int das1800_attach(struct comedi_device *dev,
 	if (!devpriv->fifo_buf)
 		return -ENOMEM;
 
-	dev->pacer = comedi_8254_init(dev->iobase + DAS1800_COUNTER,
-				      I8254_OSC_BASE_5MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + DAS1800_COUNTER,
+					  I8254_OSC_BASE_5MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
diff --git a/drivers/comedi/drivers/das6402.c b/drivers/comedi/drivers/das6402.c
index 1af394591e..68f95330de 100644
--- a/drivers/comedi/drivers/das6402.c
+++ b/drivers/comedi/drivers/das6402.c
@@ -590,10 +590,10 @@ static int das6402_attach(struct comedi_device *dev,
 		}
 	}
 
-	dev->pacer = comedi_8254_init(dev->iobase + DAS6402_TIMER_BASE,
-				      I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + DAS6402_TIMER_BASE,
+					  I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
diff --git a/drivers/comedi/drivers/das800.c b/drivers/comedi/drivers/das800.c
index 4ca33f46ea..3007755230 100644
--- a/drivers/comedi/drivers/das800.c
+++ b/drivers/comedi/drivers/das800.c
@@ -672,10 +672,10 @@ static int das800_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 			dev->irq = irq;
 	}
 
-	dev->pacer = comedi_8254_init(dev->iobase + DAS800_8254,
-				      I8254_OSC_BASE_1MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + DAS800_8254,
+					  I8254_OSC_BASE_1MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 3);
 	if (ret)
diff --git a/drivers/comedi/drivers/dmm32at.c b/drivers/comedi/drivers/dmm32at.c
index fe023c722a..644e3b643c 100644
--- a/drivers/comedi/drivers/dmm32at.c
+++ b/drivers/comedi/drivers/dmm32at.c
@@ -599,7 +599,8 @@ static int dmm32at_attach(struct comedi_device *dev,
 
 	/* Digital I/O subdevice */
 	s = &dev->subdevices[2];
-	return subdev_8255_init(dev, s, dmm32at_8255_io, DMM32AT_8255_IOBASE);
+	return subdev_8255_cb_init(dev, s, dmm32at_8255_io,
+				   DMM32AT_8255_IOBASE);
 }
 
 static struct comedi_driver dmm32at_driver = {
diff --git a/drivers/comedi/drivers/me4000.c b/drivers/comedi/drivers/me4000.c
index 9aea02b86e..7dd3a00718 100644
--- a/drivers/comedi/drivers/me4000.c
+++ b/drivers/comedi/drivers/me4000.c
@@ -1209,9 +1209,9 @@ static int me4000_auto_attach(struct comedi_device *dev,
 		if (!timer_base)
 			return -ENODEV;
 
-		dev->pacer = comedi_8254_init(timer_base, 0, I8254_IO8, 0);
-		if (!dev->pacer)
-			return -ENOMEM;
+		dev->pacer = comedi_8254_io_alloc(timer_base, 0, I8254_IO8, 0);
+		if (IS_ERR(dev->pacer))
+			return PTR_ERR(dev->pacer);
 
 		comedi_8254_subdevice_init(s, dev->pacer);
 	} else {
diff --git a/drivers/comedi/drivers/ni_at_a2150.c b/drivers/comedi/drivers/ni_at_a2150.c
index df8d219e67..e4e5a0ebd1 100644
--- a/drivers/comedi/drivers/ni_at_a2150.c
+++ b/drivers/comedi/drivers/ni_at_a2150.c
@@ -707,10 +707,10 @@ static int a2150_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	/* an IRQ and DMA are required to support async commands */
 	a2150_alloc_irq_and_dma(dev, it);
 
-	dev->pacer = comedi_8254_init(dev->iobase + I8253_BASE_REG,
-				      0, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + I8253_BASE_REG,
+					  0, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 1);
 	if (ret)
diff --git a/drivers/comedi/drivers/ni_at_ao.c b/drivers/comedi/drivers/ni_at_ao.c
index 9f3147b72a..9cf6b4ff6b 100644
--- a/drivers/comedi/drivers/ni_at_ao.c
+++ b/drivers/comedi/drivers/ni_at_ao.c
@@ -303,10 +303,10 @@ static int atao_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	if (!devpriv)
 		return -ENOMEM;
 
-	dev->pacer = comedi_8254_init(dev->iobase + ATAO_82C53_BASE,
-				      0, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + ATAO_82C53_BASE,
+					  0, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
diff --git a/drivers/comedi/drivers/ni_atmio16d.c b/drivers/comedi/drivers/ni_atmio16d.c
index 9fa902529a..e5e7cc423c 100644
--- a/drivers/comedi/drivers/ni_atmio16d.c
+++ b/drivers/comedi/drivers/ni_atmio16d.c
@@ -677,7 +677,7 @@ static int atmio16d_attach(struct comedi_device *dev,
 	/* 8255 subdevice */
 	s = &dev->subdevices[3];
 	if (board->has_8255) {
-		ret = subdev_8255_init(dev, s, NULL, 0x00);
+		ret = subdev_8255_io_init(dev, s, 0x00);
 		if (ret)
 			return ret;
 	} else {
diff --git a/drivers/comedi/drivers/ni_daq_dio24.c b/drivers/comedi/drivers/ni_daq_dio24.c
index 4877331110..9419caf02e 100644
--- a/drivers/comedi/drivers/ni_daq_dio24.c
+++ b/drivers/comedi/drivers/ni_daq_dio24.c
@@ -45,7 +45,7 @@ static int dio24_auto_attach(struct comedi_device *dev,
 
 	/* 8255 dio */
 	s = &dev->subdevices[0];
-	return subdev_8255_init(dev, s, NULL, 0x00);
+	return subdev_8255_io_init(dev, s, 0x00);
 }
 
 static struct comedi_driver driver_dio24 = {
diff --git a/drivers/comedi/drivers/ni_labpc_common.c b/drivers/comedi/drivers/ni_labpc_common.c
index 7632496532..7e0ce0ce0a 100644
--- a/drivers/comedi/drivers/ni_labpc_common.c
+++ b/drivers/comedi/drivers/ni_labpc_common.c
@@ -78,6 +78,9 @@ static const struct comedi_lrange range_labpc_ao = {
  * functions that do inb/outb and readb/writeb so we can use
  * function pointers to decide which to use
  */
+
+#ifdef CONFIG_HAS_IOPORT
+
 static unsigned int labpc_inb(struct comedi_device *dev, unsigned long reg)
 {
 	return inb(dev->iobase + reg);
@@ -89,6 +92,8 @@ static void labpc_outb(struct comedi_device *dev,
 	outb(byte, dev->iobase + reg);
 }
 
+#endif	/* CONFIG_HAS_IOPORT */
+
 static unsigned int labpc_readb(struct comedi_device *dev, unsigned long reg)
 {
 	return readb(dev->mmio + reg);
@@ -1200,8 +1205,12 @@ int labpc_common_attach(struct comedi_device *dev,
 		devpriv->read_byte = labpc_readb;
 		devpriv->write_byte = labpc_writeb;
 	} else {
+#ifdef CONFIG_HAS_IOPORT
 		devpriv->read_byte = labpc_inb;
 		devpriv->write_byte = labpc_outb;
+#else
+		return -ENXIO;
+#endif
 	}
 
 	/* initialize board's command registers */
@@ -1222,24 +1231,24 @@ int labpc_common_attach(struct comedi_device *dev,
 	}
 
 	if (dev->mmio) {
-		dev->pacer = comedi_8254_mm_init(dev->mmio + COUNTER_B_BASE_REG,
-						 I8254_OSC_BASE_2MHZ,
-						 I8254_IO8, 0);
-		devpriv->counter = comedi_8254_mm_init(dev->mmio +
-						       COUNTER_A_BASE_REG,
-						       I8254_OSC_BASE_2MHZ,
-						       I8254_IO8, 0);
+		dev->pacer =
+		    comedi_8254_mm_alloc(dev->mmio + COUNTER_B_BASE_REG,
+					 I8254_OSC_BASE_2MHZ, I8254_IO8, 0);
+		devpriv->counter =
+		    comedi_8254_mm_alloc(dev->mmio + COUNTER_A_BASE_REG,
+					 I8254_OSC_BASE_2MHZ, I8254_IO8, 0);
 	} else {
-		dev->pacer = comedi_8254_init(dev->iobase + COUNTER_B_BASE_REG,
-					      I8254_OSC_BASE_2MHZ,
-					      I8254_IO8, 0);
-		devpriv->counter = comedi_8254_init(dev->iobase +
-						    COUNTER_A_BASE_REG,
-						    I8254_OSC_BASE_2MHZ,
-						    I8254_IO8, 0);
+		dev->pacer =
+		    comedi_8254_io_alloc(dev->iobase + COUNTER_B_BASE_REG,
+					 I8254_OSC_BASE_2MHZ, I8254_IO8, 0);
+		devpriv->counter =
+		    comedi_8254_io_alloc(dev->iobase + COUNTER_A_BASE_REG,
+					 I8254_OSC_BASE_2MHZ, I8254_IO8, 0);
 	}
-	if (!dev->pacer || !devpriv->counter)
-		return -ENOMEM;
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
+	if (IS_ERR(devpriv->counter))
+		return PTR_ERR(devpriv->counter);
 
 	ret = comedi_alloc_subdevices(dev, 5);
 	if (ret)
@@ -1287,9 +1296,9 @@ int labpc_common_attach(struct comedi_device *dev,
 	/* 8255 dio */
 	s = &dev->subdevices[2];
 	if (dev->mmio)
-		ret = subdev_8255_mm_init(dev, s, NULL, DIO_BASE_REG);
+		ret = subdev_8255_mm_init(dev, s, DIO_BASE_REG);
 	else
-		ret = subdev_8255_init(dev, s, NULL, DIO_BASE_REG);
+		ret = subdev_8255_io_init(dev, s, DIO_BASE_REG);
 	if (ret)
 		return ret;
 
@@ -1341,8 +1350,10 @@ void labpc_common_detach(struct comedi_device *dev)
 {
 	struct labpc_private *devpriv = dev->private;
 
-	if (devpriv)
-		kfree(devpriv->counter);
+	if (devpriv) {
+		if (!IS_ERR(devpriv->counter))
+			kfree(devpriv->counter);
+	}
 }
 EXPORT_SYMBOL_GPL(labpc_common_detach);
 
diff --git a/drivers/comedi/drivers/ni_mio_common.c b/drivers/comedi/drivers/ni_mio_common.c
index d399985658..980f309d6d 100644
--- a/drivers/comedi/drivers/ni_mio_common.c
+++ b/drivers/comedi/drivers/ni_mio_common.c
@@ -46,6 +46,12 @@
 #include <linux/comedi/comedi_8255.h>
 #include "mite.h"
 
+#ifdef PCIDMA
+#define IS_PCIMIO 1
+#else
+#define IS_PCIMIO 0
+#endif
+
 /* A timeout count */
 #define NI_TIMEOUT 1000
 
@@ -219,54 +225,72 @@ enum timebase_nanoseconds {
 
 static const int num_adc_stages_611x = 3;
 
+#ifdef PCIDMA
+
 static void ni_writel(struct comedi_device *dev, unsigned int data, int reg)
 {
-	if (dev->mmio)
-		writel(data, dev->mmio + reg);
-	else
-		outl(data, dev->iobase + reg);
+	writel(data, dev->mmio + reg);
 }
 
 static void ni_writew(struct comedi_device *dev, unsigned int data, int reg)
 {
-	if (dev->mmio)
-		writew(data, dev->mmio + reg);
-	else
-		outw(data, dev->iobase + reg);
+	writew(data, dev->mmio + reg);
 }
 
 static void ni_writeb(struct comedi_device *dev, unsigned int data, int reg)
 {
-	if (dev->mmio)
-		writeb(data, dev->mmio + reg);
-	else
-		outb(data, dev->iobase + reg);
+	writeb(data, dev->mmio + reg);
 }
 
 static unsigned int ni_readl(struct comedi_device *dev, int reg)
 {
-	if (dev->mmio)
-		return readl(dev->mmio + reg);
+	return readl(dev->mmio + reg);
+}
+
+static unsigned int ni_readw(struct comedi_device *dev, int reg)
+{
+	return readw(dev->mmio + reg);
+}
+
+static unsigned int ni_readb(struct comedi_device *dev, int reg)
+{
+	return readb(dev->mmio + reg);
+}
 
+#else /* PCIDMA */
+
+static void ni_writel(struct comedi_device *dev, unsigned int data, int reg)
+{
+	outl(data, dev->iobase + reg);
+}
+
+static void ni_writew(struct comedi_device *dev, unsigned int data, int reg)
+{
+	outw(data, dev->iobase + reg);
+}
+
+static void ni_writeb(struct comedi_device *dev, unsigned int data, int reg)
+{
+	outb(data, dev->iobase + reg);
+}
+
+static unsigned int ni_readl(struct comedi_device *dev, int reg)
+{
 	return inl(dev->iobase + reg);
 }
 
 static unsigned int ni_readw(struct comedi_device *dev, int reg)
 {
-	if (dev->mmio)
-		return readw(dev->mmio + reg);
-
 	return inw(dev->iobase + reg);
 }
 
 static unsigned int ni_readb(struct comedi_device *dev, int reg)
 {
-	if (dev->mmio)
-		return readb(dev->mmio + reg);
-
 	return inb(dev->iobase + reg);
 }
 
+#endif /* PCIDMA */
+
 /*
  * We automatically take advantage of STC registers that can be
  * read/written directly in the I/O space of the board.
@@ -5977,6 +6001,12 @@ static int ni_E_init(struct comedi_device *dev,
 	int i;
 	const char *dev_family = devpriv->is_m_series ? "ni_mseries"
 						      : "ni_eseries";
+	if (!IS_PCIMIO != !dev->mmio) {
+		dev_err(dev->class_dev,
+			"%s: bug! %s device not supported.\n",
+			KBUILD_MODNAME, board->name);
+		return -ENXIO;
+	}
 
 	/* prepare the device for globally-named routes. */
 	if (ni_assign_device_routes(dev_family, board->name,
@@ -6137,8 +6167,8 @@ static int ni_E_init(struct comedi_device *dev,
 	/* 8255 device */
 	s = &dev->subdevices[NI_8255_DIO_SUBDEV];
 	if (board->has_8255) {
-		ret = subdev_8255_init(dev, s, ni_8255_callback,
-				       NI_E_8255_BASE);
+		ret = subdev_8255_cb_init(dev, s, ni_8255_callback,
+					  NI_E_8255_BASE);
 		if (ret)
 			return ret;
 	} else {
diff --git a/drivers/comedi/drivers/pcl711.c b/drivers/comedi/drivers/pcl711.c
index 05172c553c..0cf3917def 100644
--- a/drivers/comedi/drivers/pcl711.c
+++ b/drivers/comedi/drivers/pcl711.c
@@ -429,10 +429,10 @@ static int pcl711_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 			dev->irq = it->options[1];
 	}
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCL711_TIMER_BASE,
-				      I8254_OSC_BASE_2MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCL711_TIMER_BASE,
+					  I8254_OSC_BASE_2MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
diff --git a/drivers/comedi/drivers/pcl724.c b/drivers/comedi/drivers/pcl724.c
index 948a0576c9..00474710b8 100644
--- a/drivers/comedi/drivers/pcl724.c
+++ b/drivers/comedi/drivers/pcl724.c
@@ -124,10 +124,10 @@ static int pcl724_attach(struct comedi_device *dev,
 		s = &dev->subdevices[i];
 		if (board->is_pet48) {
 			iobase = dev->iobase + (i * 0x1000);
-			ret = subdev_8255_init(dev, s, pcl724_8255mapped_io,
-					       iobase);
+			ret = subdev_8255_cb_init(dev, s, pcl724_8255mapped_io,
+						  iobase);
 		} else {
-			ret = subdev_8255_init(dev, s, NULL, i * I8255_SIZE);
+			ret = subdev_8255_io_init(dev, s, i * I8255_SIZE);
 		}
 		if (ret)
 			return ret;
diff --git a/drivers/comedi/drivers/pcl812.c b/drivers/comedi/drivers/pcl812.c
index 70dbc129fc..0df639c6a5 100644
--- a/drivers/comedi/drivers/pcl812.c
+++ b/drivers/comedi/drivers/pcl812.c
@@ -1143,11 +1143,11 @@ static int pcl812_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 		return ret;
 
 	if (board->irq_bits) {
-		dev->pacer = comedi_8254_init(dev->iobase + PCL812_TIMER_BASE,
-					      I8254_OSC_BASE_2MHZ,
-					      I8254_IO8, 0);
-		if (!dev->pacer)
-			return -ENOMEM;
+		dev->pacer =
+		    comedi_8254_io_alloc(dev->iobase + PCL812_TIMER_BASE,
+					 I8254_OSC_BASE_2MHZ, I8254_IO8, 0);
+		if (IS_ERR(dev->pacer))
+			return PTR_ERR(dev->pacer);
 
 		if ((1 << it->options[1]) & board->irq_bits) {
 			ret = request_irq(it->options[1], pcl812_interrupt, 0,
diff --git a/drivers/comedi/drivers/pcl816.c b/drivers/comedi/drivers/pcl816.c
index a5e5320be6..28d1a88c50 100644
--- a/drivers/comedi/drivers/pcl816.c
+++ b/drivers/comedi/drivers/pcl816.c
@@ -615,10 +615,10 @@ static int pcl816_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	/* an IRQ and DMA are required to support async commands */
 	pcl816_alloc_irq_and_dma(dev, it);
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCL816_TIMER_BASE,
-				      I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCL816_TIMER_BASE,
+					  I8254_OSC_BASE_10MHZ, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	ret = comedi_alloc_subdevices(dev, 4);
 	if (ret)
diff --git a/drivers/comedi/drivers/pcl818.c b/drivers/comedi/drivers/pcl818.c
index 29e503de82..4127adcfb2 100644
--- a/drivers/comedi/drivers/pcl818.c
+++ b/drivers/comedi/drivers/pcl818.c
@@ -1015,10 +1015,10 @@ static int pcl818_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 	else
 		osc_base = I8254_OSC_BASE_1MHZ;
 
-	dev->pacer = comedi_8254_init(dev->iobase + PCL818_TIMER_BASE,
-				      osc_base, I8254_IO8, 0);
-	if (!dev->pacer)
-		return -ENOMEM;
+	dev->pacer = comedi_8254_io_alloc(dev->iobase + PCL818_TIMER_BASE,
+					  osc_base, I8254_IO8, 0);
+	if (IS_ERR(dev->pacer))
+		return PTR_ERR(dev->pacer);
 
 	/* max sampling speed */
 	devpriv->ns_min = board->ns_min;
diff --git a/drivers/comedi/drivers/pcm3724.c b/drivers/comedi/drivers/pcm3724.c
index ca8bef54da..fb41de3bae 100644
--- a/drivers/comedi/drivers/pcm3724.c
+++ b/drivers/comedi/drivers/pcm3724.c
@@ -204,7 +204,7 @@ static int pcm3724_attach(struct comedi_device *dev,
 
 	for (i = 0; i < dev->n_subdevices; i++) {
 		s = &dev->subdevices[i];
-		ret = subdev_8255_init(dev, s, NULL, i * I8255_SIZE);
+		ret = subdev_8255_io_init(dev, s, i * I8255_SIZE);
 		if (ret)
 			return ret;
 		s->insn_config = subdev_3724_insn_config;
diff --git a/drivers/comedi/drivers/rtd520.c b/drivers/comedi/drivers/rtd520.c
index 7e0ec1a2a2..44bb0decd7 100644
--- a/drivers/comedi/drivers/rtd520.c
+++ b/drivers/comedi/drivers/rtd520.c
@@ -1289,9 +1289,9 @@ static int rtd_auto_attach(struct comedi_device *dev,
 
 	/* 8254 Timer/Counter subdevice */
 	s = &dev->subdevices[3];
-	dev->pacer = comedi_8254_mm_init(dev->mmio + LAS0_8254_TIMER_BASE,
-					 RTD_CLOCK_BASE, I8254_IO8, 2);
-	if (!dev->pacer)
+	dev->pacer = comedi_8254_mm_alloc(dev->mmio + LAS0_8254_TIMER_BASE,
+					  RTD_CLOCK_BASE, I8254_IO8, 2);
+	if (IS_ERR(dev->pacer))
 		return -ENOMEM;
 
 	comedi_8254_subdevice_init(s, dev->pacer);