staging: comedi: comedi_8255: new module split from 8255

The Comedi "8255" module is both a standalone Comedi device driver
module for simple devices with one or more 8255 "Programmable Peripheral
Interface" chips at known I/O base addresses (configured at run-time),
and a helper module to configure a 8255-based digital I/O subdevice for
other Comedi drivers.

Split the "8255 subdevice helper" functionality into a new module:
"comedi_8255", leaving the standalone 8255 Comedi driver in the "8255"
module.

The Comedi "detach" routine of the standalone "8255" driver needs to
retrieve the I/O base address passed to the "comedi_8255" module to set
up each subdevice in order to release the I/O port regions it requested
in its "attach" routine.  The "comedi_8255" module stores it in a
"subdevice private" data structure that is no longer known to the "8255"
module, so add a new, exported function `subdev_8255_regbase()` to
retrieve it.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/Kconfig

@@ -1247,16 +1247,22 @@ config COMEDI_8254
 	tristate
 
 config COMEDI_8255
-	tristate "Generic 8255 support"
+	tristate
+
+config COMEDI_8255_SA
+	tristate "Standalone 8255 support"
+	select COMEDI_8255
 	---help---
-	  Enable generic 8255 support.
+	  Enable support for 8255 digital I/O as a standalone driver.
 
 	  You should enable compilation this driver if you plan to use a board
-	  that has an 8255 chip. For multifunction boards, the main driver will
-	  configure the 8255 subdevice automatically.
+	  that has an 8255 chip at a known I/O base address and there are no
+	  other Comedi drivers for the board.
 
-	  Note that most PCI based 8255 boards use the 8255_pci driver as a
-	  wrapper around this driver.
+	  Note that Comedi drivers for most multi-function boards incorporating
+	  an 8255 chip use the 'comedi_8255' module.  Most PCI-based 8255
+	  boards use the 8255_pci driver as a wrapper around the 'comedi_8255'
+	  module.
 
 	  To compile this driver as a module, choose M here: the module will be
 	  called 8255.

drivers/staging/comedi/drivers/8255.c

@@ -53,221 +53,6 @@
 
 #include "8255.h"
 
-struct subdev_8255_private {
-	unsigned long regbase;
-	int (*io)(struct comedi_device *dev, int dir, int port, int data,
-		  unsigned long regbase);
-};
-
-static int subdev_8255_io(struct comedi_device *dev,
-			  int dir, int port, int data, unsigned long regbase)
-{
-	if (dir) {
-		outb(data, dev->iobase + regbase + port);
-		return 0;
-	}
-	return inb(dev->iobase + regbase + port);
-}
-
-static int subdev_8255_mmio(struct comedi_device *dev,
-			    int dir, int port, int data, unsigned long regbase)
-{
-	if (dir) {
-		writeb(data, dev->mmio + regbase + port);
-		return 0;
-	}
-	return readb(dev->mmio + regbase + port);
-}
-
-static int subdev_8255_insn(struct comedi_device *dev,
-			    struct comedi_subdevice *s,
-			    struct comedi_insn *insn,
-			    unsigned int *data)
-{
-	struct subdev_8255_private *spriv = s->private;
-	unsigned long regbase = spriv->regbase;
-	unsigned int mask;
-	unsigned int v;
-
-	mask = comedi_dio_update_state(s, data);
-	if (mask) {
-		if (mask & 0xff)
-			spriv->io(dev, 1, I8255_DATA_A_REG,
-				  s->state & 0xff, regbase);
-		if (mask & 0xff00)
-			spriv->io(dev, 1, I8255_DATA_B_REG,
-				  (s->state >> 8) & 0xff, regbase);
-		if (mask & 0xff0000)
-			spriv->io(dev, 1, I8255_DATA_C_REG,
-				  (s->state >> 16) & 0xff, regbase);
-	}
-
-	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);
-
-	data[1] = v;
-
-	return insn->n;
-}
-
-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;
-	int config;
-
-	config = I8255_CTRL_CW;
-	/* 1 in io_bits indicates output, 1 in config indicates input */
-	if (!(s->io_bits & 0x0000ff))
-		config |= I8255_CTRL_A_IO;
-	if (!(s->io_bits & 0x00ff00))
-		config |= I8255_CTRL_B_IO;
-	if (!(s->io_bits & 0x0f0000))
-		config |= I8255_CTRL_C_LO_IO;
-	if (!(s->io_bits & 0xf00000))
-		config |= I8255_CTRL_C_HI_IO;
-
-	spriv->io(dev, 1, I8255_CTRL_REG, config, regbase);
-}
-
-static int subdev_8255_insn_config(struct comedi_device *dev,
-				   struct comedi_subdevice *s,
-				   struct comedi_insn *insn,
-				   unsigned int *data)
-{
-	unsigned int chan = CR_CHAN(insn->chanspec);
-	unsigned int mask;
-	int ret;
-
-	if (chan < 8)
-		mask = 0x0000ff;
-	else if (chan < 16)
-		mask = 0x00ff00;
-	else if (chan < 20)
-		mask = 0x0f0000;
-	else
-		mask = 0xf00000;
-
-	ret = comedi_dio_insn_config(dev, s, insn, data, mask);
-	if (ret)
-		return ret;
-
-	subdev_8255_do_config(dev, s);
-
-	return insn->n;
-}
-
-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)
-{
-	struct subdev_8255_private *spriv;
-
-	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;
-
-	s->type		= COMEDI_SUBD_DIO;
-	s->subdev_flags	= SDF_READABLE | SDF_WRITABLE;
-	s->n_chan	= 24;
-	s->range_table	= &range_digital;
-	s->maxdata	= 1;
-	s->insn_bits	= subdev_8255_insn;
-	s->insn_config	= subdev_8255_insn_config;
-
-	subdev_8255_do_config(dev, s);
-
-	return 0;
-}
-
-/**
- * subdev_8255_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
- *
- * 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),
-		     unsigned long regbase)
-{
-	return __subdev_8255_init(dev, s, io, regbase, false);
-}
-EXPORT_SYMBOL_GPL(subdev_8255_init);
-
-/**
- * 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
- *
- * 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 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 (*io)(struct comedi_device *dev, int dir, int port,
-				  int data, unsigned long regbase),
-			unsigned long regbase)
-{
-	return __subdev_8255_init(dev, s, io, regbase, true);
-}
-EXPORT_SYMBOL_GPL(subdev_8255_mm_init);
-
-/*
- * Start of the 8255 standalone device
- */
-
 static int dev_8255_attach(struct comedi_device *dev,
 			   struct comedi_devconfig *it)
 {
@@ -324,14 +109,14 @@ static int dev_8255_attach(struct comedi_device *dev,
 static void dev_8255_detach(struct comedi_device *dev)
 {
 	struct comedi_subdevice *s;
-	struct subdev_8255_private *spriv;
 	int i;
 
 	for (i = 0; i < dev->n_subdevices; i++) {
 		s = &dev->subdevices[i];
 		if (s->type != COMEDI_SUBD_UNUSED) {
-			spriv = s->private;
-			release_region(spriv->regbase, I8255_SIZE);
+			unsigned long regbase = subdev_8255_regbase(s);
+
+			release_region(regbase, I8255_SIZE);
 		}
 	}
 }
@@ -345,5 +130,5 @@ static struct comedi_driver dev_8255_driver = {
 module_comedi_driver(dev_8255_driver);
 
 MODULE_AUTHOR("Comedi http://www.comedi.org");
-MODULE_DESCRIPTION("Comedi low-level driver");
+MODULE_DESCRIPTION("Comedi driver for standalone 8255 devices");
 MODULE_LICENSE("GPL");

drivers/staging/comedi/drivers/8255.h

@@ -46,4 +46,6 @@ int subdev_8255_mm_init(struct comedi_device *dev, struct comedi_subdevice *s,
 				  int data, unsigned long regbase),
 			unsigned long regbase);
 
+unsigned long subdev_8255_regbase(struct comedi_subdevice *s);
+
 #endif

drivers/staging/comedi/drivers/Makefile

@@ -139,7 +139,8 @@ obj-$(CONFIG_COMEDI_NI_TIOCMD)		+= ni_tiocmd.o
 obj-$(CONFIG_COMEDI_NI_LABPC)		+= ni_labpc_common.o
 obj-$(CONFIG_COMEDI_NI_LABPC_ISADMA)	+= ni_labpc_isadma.o
 
-obj-$(CONFIG_COMEDI_8255)		+= 8255.o
+obj-$(CONFIG_COMEDI_8255)		+= comedi_8255.o
+obj-$(CONFIG_COMEDI_8255_SA)		+= 8255.o
 obj-$(CONFIG_COMEDI_AMPLC_DIO200)	+= amplc_dio200_common.o
 obj-$(CONFIG_COMEDI_AMPLC_PC236)	+= amplc_pc236_common.o
 obj-$(CONFIG_COMEDI_DAS08)		+= das08.o

drivers/staging/comedi/drivers/comedi_8255.c

+/*
+ * comedi_8255.c
+ * Generic 8255 digital I/O support
+ *
+ * Split from the Comedi "8255" driver module.
+ *
+ * COMEDI - Linux Control and Measurement Device Interface
+ * Copyright (C) 1998 David A. Schleef <ds@schleef.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+/*
+ * Module: comedi_8255
+ * Description: Generic 8255 support
+ * Author: ds
+ * Updated: Fri, 22 May 2015 12:14:17 +0000
+ * Status: works
+ *
+ * This module is not used directly by end-users.  Rather, it is used by
+ * other drivers to provide support for an 8255 "Programmable Peripheral
+ * Interface" (PPI) chip.
+ *
+ * The classic in digital I/O.  The 8255 appears in Comedi as a single
+ * digital I/O subdevice with 24 channels.  The channel 0 corresponds to
+ * the 8255's port A, bit 0; channel 23 corresponds to port C, bit 7.
+ * Direction configuration is done in blocks, with channels 0-7, 8-15,
+ * 16-19, and 20-23 making up the 4 blocks.  The only 8255 mode
+ * supported is mode 0.
+ */
+
+#include <linux/module.h>
+#include "../comedidev.h"
+
+#include "8255.h"
+
+struct subdev_8255_private {
+	unsigned long regbase;
+	int (*io)(struct comedi_device *dev, int dir, int port, int data,
+		  unsigned long regbase);
+};
+
+static int subdev_8255_io(struct comedi_device *dev,
+			  int dir, int port, int data, unsigned long regbase)
+{
+	if (dir) {
+		outb(data, dev->iobase + regbase + port);
+		return 0;
+	}
+	return inb(dev->iobase + regbase + port);
+}
+
+static int subdev_8255_mmio(struct comedi_device *dev,
+			    int dir, int port, int data, unsigned long regbase)
+{
+	if (dir) {
+		writeb(data, dev->mmio + regbase + port);
+		return 0;
+	}
+	return readb(dev->mmio + regbase + port);
+}
+
+static int subdev_8255_insn(struct comedi_device *dev,
+			    struct comedi_subdevice *s,
+			    struct comedi_insn *insn,
+			    unsigned int *data)
+{
+	struct subdev_8255_private *spriv = s->private;
+	unsigned long regbase = spriv->regbase;
+	unsigned int mask;
+	unsigned int v;
+
+	mask = comedi_dio_update_state(s, data);
+	if (mask) {
+		if (mask & 0xff)
+			spriv->io(dev, 1, I8255_DATA_A_REG,
+				  s->state & 0xff, regbase);
+		if (mask & 0xff00)
+			spriv->io(dev, 1, I8255_DATA_B_REG,
+				  (s->state >> 8) & 0xff, regbase);
+		if (mask & 0xff0000)
+			spriv->io(dev, 1, I8255_DATA_C_REG,
+				  (s->state >> 16) & 0xff, regbase);
+	}
+
+	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);
+
+	data[1] = v;
+
+	return insn->n;
+}
+
+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;
+	int config;
+
+	config = I8255_CTRL_CW;
+	/* 1 in io_bits indicates output, 1 in config indicates input */
+	if (!(s->io_bits & 0x0000ff))
+		config |= I8255_CTRL_A_IO;
+	if (!(s->io_bits & 0x00ff00))
+		config |= I8255_CTRL_B_IO;
+	if (!(s->io_bits & 0x0f0000))
+		config |= I8255_CTRL_C_LO_IO;
+	if (!(s->io_bits & 0xf00000))
+		config |= I8255_CTRL_C_HI_IO;
+
+	spriv->io(dev, 1, I8255_CTRL_REG, config, regbase);
+}
+
+static int subdev_8255_insn_config(struct comedi_device *dev,
+				   struct comedi_subdevice *s,
+				   struct comedi_insn *insn,
+				   unsigned int *data)
+{
+	unsigned int chan = CR_CHAN(insn->chanspec);
+	unsigned int mask;
+	int ret;
+
+	if (chan < 8)
+		mask = 0x0000ff;
+	else if (chan < 16)
+		mask = 0x00ff00;
+	else if (chan < 20)
+		mask = 0x0f0000;
+	else
+		mask = 0xf00000;
+
+	ret = comedi_dio_insn_config(dev, s, insn, data, mask);
+	if (ret)
+		return ret;
+
+	subdev_8255_do_config(dev, s);
+
+	return insn->n;
+}
+
+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)
+{
+	struct subdev_8255_private *spriv;
+
+	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;
+
+	s->type		= COMEDI_SUBD_DIO;
+	s->subdev_flags	= SDF_READABLE | SDF_WRITABLE;
+	s->n_chan	= 24;
+	s->range_table	= &range_digital;
+	s->maxdata	= 1;
+	s->insn_bits	= subdev_8255_insn;
+	s->insn_config	= subdev_8255_insn_config;
+
+	subdev_8255_do_config(dev, s);
+
+	return 0;
+}
+
+/**
+ * subdev_8255_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
+ *
+ * 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),
+		     unsigned long regbase)
+{
+	return __subdev_8255_init(dev, s, io, regbase, false);
+}
+EXPORT_SYMBOL_GPL(subdev_8255_init);
+
+/**
+ * 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
+ *
+ * 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 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 (*io)(struct comedi_device *dev, int dir, int port,
+				  int data, unsigned long regbase),
+			unsigned long regbase)
+{
+	return __subdev_8255_init(dev, s, io, regbase, true);
+}
+EXPORT_SYMBOL_GPL(subdev_8255_mm_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 to
+ * subdev_8255_init() or subdev_8255_mm_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;
+}
+EXPORT_SYMBOL_GPL(subdev_8255_regbase);
+
+static int __init comedi_8255_module_init(void)
+{
+	return 0;
+}
+module_init(comedi_8255_module_init);
+
+static void __exit comedi_8255_module_exit(void)
+{
+}
+module_exit(comedi_8255_module_exit);
+
+MODULE_AUTHOR("Comedi http://www.comedi.org");
+MODULE_DESCRIPTION("Comedi: Generic 8255 digital I/O support");
+MODULE_LICENSE("GPL");