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comedi: comedi_8254: Use a call-back function for register access
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Rework the comedi_8254 module to use a call-back function for register
access.  This will make it easier to isolate the parts that will depend
on the `CONFIG_HAS_IOPORT` macro being defined and also allows the
possibility of supplying an external callback function during
initialization by a variant of the `comedi_8254_init()` and
`comedi_8254_mm_init()` functions, although that has not been
implemented yet.

The `struct comedi_8254` members have been changed to use a pointer to a
callback function and a context of type `unsigned long`.  The
`comedi_8254_init()` and `comedi_8254_mm_init()` functions use an
internal callback function and set the context to the base address of
the registers (for `comedi_8254_mm_init()` that involves converting a
`void __iomem *` to `unsigned long`).

A minor change to `dio200_subdev_8254_offset()` in the
amplc_dio200_common module has been made due to the changes in `struct
comedi_8254`.

Cc: Arnd Bergmann <[email protected]>
Cc: Niklas Schnelle <[email protected]>
Signed-off-by: Ian Abbott <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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@ian-abbott @gregkh
ian-abbott authored and gregkh committed Oct 5, 2023
1 parent 7b79e3d commit c62f503
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Showing 3 changed files with 144 additions and 59 deletions.
4 changes: 2 additions & 2 deletions drivers/comedi/drivers/amplc_dio200_common.c
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Original file line number Diff line number Diff line change
Expand Up @@ -149,9 +149,9 @@ 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)
Expand Down
177 changes: 124 additions & 53 deletions drivers/comedi/drivers/comedi_8254.c
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Original file line number Diff line number Diff line change
Expand Up @@ -119,63 +119,101 @@
#include <linux/comedi/comedidev.h>
#include <linux/comedi/comedi_8254.h>

static unsigned int __i8254_read(struct comedi_8254 *i8254, unsigned int reg)
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);
}
}

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
Expand Down Expand Up @@ -571,8 +609,8 @@ 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)
Expand All @@ -585,12 +623,15 @@ static struct comedi_8254 *__i8254_init(unsigned long iobase,
iosize == I8254_IO32))
return NULL;

if (!iocb)
return NULL;

i8254 = kzalloc(sizeof(*i8254), GFP_KERNEL);
if (!i8254)
return NULL;

i8254->iobase = iobase;
i8254->mmio = mmio;
i8254->iocb = iocb;
i8254->context = context;
i8254->iosize = iosize;
i8254->regshift = regshift;

Expand All @@ -617,7 +658,22 @@ struct comedi_8254 *comedi_8254_init(unsigned long iobase,
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 NULL;
}
return __i8254_init(iocb, iobase, osc_base, iosize, regshift);
}
EXPORT_SYMBOL_GPL(comedi_8254_init);

Expand All @@ -634,7 +690,22 @@ struct comedi_8254 *comedi_8254_mm_init(void __iomem *mmio,
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 NULL;
}
return __i8254_init(iocb, (unsigned long)mmio, osc_base, iosize, regshift);
}
EXPORT_SYMBOL_GPL(comedi_8254_mm_init);

Expand Down
22 changes: 18 additions & 4 deletions include/linux/comedi/comedi_8254.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -57,10 +57,24 @@ struct comedi_subdevice;
/* counter maps zero to 0x10000 */
#define I8254_MAX_COUNT 0x10000

struct comedi_8254;

/**
* typedef comedi_8254_iocb_fn - call-back function type for 8254 register access
* @i8254: pointer to struct comedi_8254
* @dir: direction (0 = read, 1 = write)
* @reg: register number
* @val: value to write
*
* Return: Register value when reading, 0 when writing.
*/
typedef unsigned int comedi_8254_iocb_fn(struct comedi_8254 *i8254, int dir,
unsigned int reg, unsigned int val);

/**
* struct comedi_8254 - private data used by this module
* @iobase: PIO base address of the registers (in/out)
* @mmio: MMIO base address of the registers (read/write)
* @iocb: I/O call-back function for register access
* @context: context for register access (e.g. a base address)
* @iosize: I/O size used to access the registers (b/w/l)
* @regshift: register gap shift
* @osc_base: cascaded oscillator speed in ns
Expand All @@ -76,8 +90,8 @@ struct comedi_subdevice;
* @insn_config: driver specific (*insn_config) callback
*/
struct comedi_8254 {
unsigned long iobase;
void __iomem *mmio;
comedi_8254_iocb_fn *iocb;
unsigned long context;
unsigned int iosize;
unsigned int regshift;
unsigned int osc_base;
Expand Down

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