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staging: comedi: jr3_pci: re-work struct jr3_pci_subdev_private range 

The `range` member of `struct jr3_pci_subdev_private` is an array of a
tag-less `struct` type whose layout is similar to `struct
comedi_lrange`.  Both `struct` types end with a member also called
`range`.  In the case of tag-less `struct` type, it is a single `struct
comedi_krange`.  In the case of `struct comedi_lrange`, it is a flexible
array of `struct comedi_krange`.

Elements of the `range` array member in `struct jr3_pci_subdev_private`
are pointed to by elements of the `range_table_list` array member, which
are of type `const struct comedi_lrange *`.  This requires some dodgy
type casting.

To avoid the dodgy type casting, change the element type of the `range`
member of `struct jr3_pci_subdev_private` to be a new type `union
jr3_pci_single_range`.  This contains a member `l` of type `struct
comedi_lrange`, and an array member `_reserved` that is large enough to
encompass the `struct comedi_lrange` plus a single `struct
comedi_krange`.  It is the same size as the previous type.  Accesses to
`spriv->range[i].length` and `spriv->range[i].range` are replaced with
`spriv->range[i].l.length` and `spriv->range[i].l.range[0]` respectively
(where `spriv` is a `struct jr3_pci_subdev_private *`, and `i` is an
array index).  Type-casted pointers to `spriv->range[i]` are replaced
with pointers to `spriv->range[i].l`, which do not require the type
casts.  Since we defined a new type, we can define local variables of
the corresponding pointer type to shorten some lines of code.  This is
made use of in `jr3_pci_alloc_spriv()`.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2017-02-17 11:09:16 +00:00 committed by Greg Kroah-Hartman
parent de98befe56
commit 4af8c81951
1 changed files with 34 additions and 34 deletions
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68
drivers/staging/comedi/drivers/jr3_pci.c
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@ -99,6 +99,11 @@ struct jr3_pci_dev_private {
struct timer_list timer;
};
union jr3_pci_single_range {
struct comedi_lrange l;
char _reserved[offsetof(struct comedi_lrange, range[1])];
};
enum jr3_pci_poll_state {
state_jr3_poll,
state_jr3_init_wait_for_offset,
@ -114,10 +119,7 @@ struct jr3_pci_subdev_private {
enum jr3_pci_poll_state state;
int serial_no;
int model_no;
struct {
int length;
struct comedi_krange range;
} range[9];
union jr3_pci_single_range range[9];
const struct comedi_lrange *range_table_list[8 * 7 + 2];
unsigned int maxdata_list[8 * 7 + 2];
u16 errors;
@ -532,27 +534,28 @@ jr3_pci_poll_subdevice(struct comedi_subdevice *s)
result = poll_delay_min_max(20, 100);
} else {
struct force_array __iomem *fs = &channel->full_scale;
union jr3_pci_single_range *r = spriv->range;
/* Use ranges in kN or we will overflow around 2000N! */
spriv->range[0].range.min = -get_s16(&fs->fx) * 1000;
spriv->range[0].range.max = get_s16(&fs->fx) * 1000;
spriv->range[1].range.min = -get_s16(&fs->fy) * 1000;
spriv->range[1].range.max = get_s16(&fs->fy) * 1000;
spriv->range[2].range.min = -get_s16(&fs->fz) * 1000;
spriv->range[2].range.max = get_s16(&fs->fz) * 1000;
spriv->range[3].range.min = -get_s16(&fs->mx) * 100;
spriv->range[3].range.max = get_s16(&fs->mx) * 100;
spriv->range[4].range.min = -get_s16(&fs->my) * 100;
spriv->range[4].range.max = get_s16(&fs->my) * 100;
spriv->range[5].range.min = -get_s16(&fs->mz) * 100;
r[0].l.range[0].min = -get_s16(&fs->fx) * 1000;
r[0].l.range[0].max = get_s16(&fs->fx) * 1000;
r[1].l.range[0].min = -get_s16(&fs->fy) * 1000;
r[1].l.range[0].max = get_s16(&fs->fy) * 1000;
r[2].l.range[0].min = -get_s16(&fs->fz) * 1000;
r[2].l.range[0].max = get_s16(&fs->fz) * 1000;
r[3].l.range[0].min = -get_s16(&fs->mx) * 100;
r[3].l.range[0].max = get_s16(&fs->mx) * 100;
r[4].l.range[0].min = -get_s16(&fs->my) * 100;
r[4].l.range[0].max = get_s16(&fs->my) * 100;
r[5].l.range[0].min = -get_s16(&fs->mz) * 100;
/* the next five are questionable */
spriv->range[5].range.max = get_s16(&fs->mz) * 100;
spriv->range[6].range.min = -get_s16(&fs->v1) * 100;
spriv->range[6].range.max = get_s16(&fs->v1) * 100;
spriv->range[7].range.min = -get_s16(&fs->v2) * 100;
spriv->range[7].range.max = get_s16(&fs->v2) * 100;
spriv->range[8].range.min = 0;
spriv->range[8].range.max = 65535;
r[5].l.range[0].max = get_s16(&fs->mz) * 100;
r[6].l.range[0].min = -get_s16(&fs->v1) * 100;
r[6].l.range[0].max = get_s16(&fs->v1) * 100;
r[7].l.range[0].min = -get_s16(&fs->v2) * 100;
r[7].l.range[0].max = get_s16(&fs->v2) * 100;
r[8].l.range[0].min = 0;
r[8].l.range[0].max = 65535;
use_offset(channel, 0);
spriv->state = state_jr3_init_use_offset_complete;
@ -643,24 +646,21 @@ jr3_pci_alloc_spriv(struct comedi_device *dev, struct comedi_subdevice *s)
spriv->channel = &devpriv->iobase->channel[s->index].data;
for (j = 0; j < 8; j++) {
spriv->range[j].length = 1;
spriv->range[j].range.min = -1000000;
spriv->range[j].range.max = 1000000;
spriv->range[j].l.length = 1;
spriv->range[j].l.range[0].min = -1000000;
spriv->range[j].l.range[0].max = 1000000;
for (k = 0; k < 7; k++) {
spriv->range_table_list[j + k * 8] =
(const struct comedi_lrange *)&spriv->range[j];
spriv->range_table_list[j + k * 8] = &spriv->range[j].l;
spriv->maxdata_list[j + k * 8] = 0x7fff;
}
}
spriv->range[8].length = 1;
spriv->range[8].range.min = 0;
spriv->range[8].range.max = 65536;
spriv->range[8].l.length = 1;
spriv->range[8].l.range[0].min = 0;
spriv->range[8].l.range[0].max = 65536;
spriv->range_table_list[56] =
(const struct comedi_lrange *)&spriv->range[8];
spriv->range_table_list[57] =
(const struct comedi_lrange *)&spriv->range[8];
spriv->range_table_list[56] = &spriv->range[8].l;
spriv->range_table_list[57] = &spriv->range[8].l;
spriv->maxdata_list[56] = 0xffff;
spriv->maxdata_list[57] = 0xffff;