Messages in this thread Patch in this message | | | Date | Mon, 14 Mar 2022 08:37:14 -0700 | From | Colin Foster <> | Subject | Re: [RFC v1 2/2] regmap: allow a defined reg_base to be added to every address |
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On Mon, Mar 14, 2022 at 08:28:36AM +0000, Mark Brown wrote: > On Sun, Mar 13, 2022 at 03:45:24PM -0700, Colin Foster wrote: > > > There's an inconsistency that arises when a register set can be accessed > > internally via MMIO, or externally via SPI. The VSC7514 chip allows both > > modes of operation. When internally accessed, the system utilizes __iomem, > > devm_ioremap_resource, and devm_regmap_init_mmio. > > > For SPI it isn't possible to utilize memory-mapped IO. To properly operate, > > the resource base must be added to the register before every operation. > > The problem here isn't the mixed buses, the problem is that the hardware > designers have for some unknown reason decided to not use the same > register addresses on the two buses which just seems pointlessly > unhelpful.
That is true for the address downshift. But the resource start seemingly still needs to be addressed somewhere. Currently that is contained on a per-regmap basis inside my WIP drivers/mfd/ocelot-spi.c. But that falls apart as soon as regmap_bus gets involved, as I'm finding out.
So would it make sense to keep this patch, drop the downshift, and re-define the offsets / stride to match the modified address space?
> > > > > Signed-off-by: Colin Foster <colin.foster@in-advantage.com> > > --- > > drivers/base/regmap/internal.h | 1 + > > drivers/base/regmap/regmap.c | 6 ++++++ > > include/linux/regmap.h | 3 +++ > > 3 files changed, 10 insertions(+) > > > > diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h > > index 88f710e7ce31..b4df36c7b17d 100644 > > --- a/drivers/base/regmap/internal.h > > +++ b/drivers/base/regmap/internal.h > > @@ -63,6 +63,7 @@ struct regmap { > > regmap_unlock unlock; > > void *lock_arg; /* This is passed to lock/unlock functions */ > > gfp_t alloc_flags; > > + unsigned int reg_base; > > > > struct device *dev; /* Device we do I/O on */ > > void *work_buf; /* Scratch buffer used to format I/O */ > > diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c > > index 1c7c6d6361af..5e12f7cb5147 100644 > > --- a/drivers/base/regmap/regmap.c > > +++ b/drivers/base/regmap/regmap.c > > @@ -821,6 +821,8 @@ struct regmap *__regmap_init(struct device *dev, > > else > > map->alloc_flags = GFP_KERNEL; > > > > + map->reg_base = config->reg_base; > > + > > map->format.reg_bytes = DIV_ROUND_UP(config->reg_bits, 8); > > map->format.pad_bytes = config->pad_bits / 8; > > map->format.reg_downshift = config->reg_downshift; > > @@ -1736,6 +1738,7 @@ static int _regmap_raw_write_impl(struct regmap *map, unsigned int reg, > > return ret; > > } > > > > + reg += map->reg_base; > > reg >>= map->format.reg_downshift; > > map->format.format_reg(map->work_buf, reg, map->reg_shift); > > regmap_set_work_buf_flag_mask(map, map->format.reg_bytes, > > @@ -1907,6 +1910,7 @@ static int _regmap_bus_formatted_write(void *context, unsigned int reg, > > return ret; > > } > > > > + reg += map->reg_base; > > reg >>= map->format.reg_downshift; > > map->format.format_write(map, reg, val); > > > > @@ -2349,6 +2353,7 @@ static int _regmap_raw_multi_reg_write(struct regmap *map, > > unsigned int reg = regs[i].reg; > > unsigned int val = regs[i].def; > > trace_regmap_hw_write_start(map, reg, 1); > > + reg += map->reg_base; > > reg >>= map->format.reg_downshift; > > map->format.format_reg(u8, reg, map->reg_shift); > > u8 += reg_bytes + pad_bytes; > > @@ -2677,6 +2682,7 @@ static int _regmap_raw_read(struct regmap *map, unsigned int reg, void *val, > > return ret; > > } > > > > + reg += map->reg_base; > > reg >>= map->format.reg_downshift; > > map->format.format_reg(map->work_buf, reg, map->reg_shift); > > regmap_set_work_buf_flag_mask(map, map->format.reg_bytes, > > diff --git a/include/linux/regmap.h b/include/linux/regmap.h > > index 40fb9399add6..de81a94d7b30 100644 > > --- a/include/linux/regmap.h > > +++ b/include/linux/regmap.h > > @@ -239,6 +239,8 @@ typedef void (*regmap_unlock)(void *); > > * used. > > * @reg_downshift: The number of bits to downshift the register before > > * performing any operations. > > + * @reg_base: Value to be added to every register address before performing any > > + * operation. > > * @pad_bits: Number of bits of padding between register and value. > > * @val_bits: Number of bits in a register value, mandatory. > > * > > @@ -363,6 +365,7 @@ struct regmap_config { > > int reg_bits; > > int reg_stride; > > int reg_downshift; > > + unsigned int reg_base; > > int pad_bits; > > int val_bits; > > > > -- > > 2.25.1 > >
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