comedi: comedi_8254: Use a call-back function for register access

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 <arnd@kernel.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20230913170712.111719-3-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/comedi/drivers/amplc_dio200_common.c b/drivers/comedi/drivers/amplc_dio200_common.c
index ff651f2eb86cd1c493e7714f61202b612615417c..2c1507a23f8af79f12c3de4e6aa5ceb72053b70e 100644 (file)
--- a/drivers/comedi/drivers/amplc_dio200_common.c
+++ b/drivers/comedi/drivers/amplc_dio200_common.c
@@ -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)

diff --git a/drivers/comedi/drivers/comedi_8254.c b/drivers/comedi/drivers/comedi_8254.c
index b4185c1b2695bcad66ccc9a6bc924d2b18438056..3f8657fc7ee5a1482f0c3d8ddc1e45ccc15a3a4e 100644 (file)
--- a/drivers/comedi/drivers/comedi_8254.c
+++ b/drivers/comedi/drivers/comedi_8254.c
@@ -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
@@ -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)
@@ -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;
 
@@ -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);
 
@@ -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);
 

diff --git a/include/linux/comedi/comedi_8254.h b/include/linux/comedi/comedi_8254.h
index d8264417e53c38d18c7c397c508ab0c999f6b122..18d12321c87d536a2e067bea7f1e47535b13cf40 100644 (file)
--- a/include/linux/comedi/comedi_8254.h
+++ b/include/linux/comedi/comedi_8254.h
@@ -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
@@ -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;