Hi Simon,
On 07/05/20 07:36PM, Simon Glass wrote:
If there a way to use DM w/o DT changes, we can definitely explore that...
You can certainly do that. Just device_bind() a driver that implements your access mechanism. So long as the driver uses the same access mechanism no matter what hardware it is running on, that makes sense. But from what you say above, that might not be true, so you would end up setting the platform data of the regmap driver from its parent. That's not terrible, but not ideal.
Given the simple access you need above, I think you could just add that as another option in the regmap, perhaps turning endianness into some flags?
I tried doing it without custom regmap accessors. The rough patch below is what I came up with. Does it look any better than custom accessors?
PS: I can probably play around with regmap ranges instead of using 'base_offset', but it gets the job done minimally so I think it is good enough for a proof-of-concept.
-- 8< -- Subject: [RFC PATCH] regmap: allow specifying base offset and register shift and access size
To accommodate more complex access patterns that are needed in the Cadence Sierra PHY driver (which will be added as a follow-up), introduce 'base_offset' and 'reg_offset_shift', two values that can be used to adjust the final regmap read/write address.
'base_offset' is an extra offset on the regmap base discovered from the device tree. This is useful when some regmaps of a device need to access memory at one offset, and some at another.
'reg_offset_shift' will shift the register offset left before access.
'size' can be used to specify the width of reads (1/2/4/8 bytes). If 0, defaults to 4 bytes to maintain backward compatibility.
Signed-off-by: Pratyush Yadav p.yadav@ti.com --- drivers/core/regmap.c | 16 ++++++++++++---- include/regmap.h | 27 ++++++++++++++++++++++++++- 2 files changed, 38 insertions(+), 5 deletions(-)
diff --git a/drivers/core/regmap.c b/drivers/core/regmap.c index 41293e5af0..9bce719b45 100644 --- a/drivers/core/regmap.c +++ b/drivers/core/regmap.c @@ -38,6 +38,7 @@ static struct regmap *regmap_alloc(int count) map = malloc(sizeof(*map) + sizeof(map->ranges[0]) * count); if (!map) return NULL; + memset(map, 0, sizeof(*map)); map->range_count = count;
return map; @@ -258,6 +259,10 @@ struct regmap *devm_regmap_init(struct udevice *dev, if (rc) return ERR_PTR(rc);
+ (*mapp)->base_offset = config->base_offset; + (*mapp)->reg_offset_shift = config->reg_offset_shift; + (*mapp)->size = config->size; + devres_add(dev, mapp); return *mapp; } @@ -343,7 +348,9 @@ int regmap_raw_read_range(struct regmap *map, uint range_num, uint offset, } range = &map->ranges[range_num];
- ptr = map_physmem(range->start + offset, val_len, MAP_NOCACHE); + offset <<= map->reg_offset_shift; + + ptr = map_physmem(range->start + map->base_offset + offset, val_len, MAP_NOCACHE);
if (offset + val_len > range->size) { debug("%s: offset/size combination invalid\n", __func__); @@ -380,7 +387,7 @@ int regmap_raw_read(struct regmap *map, uint offset, void *valp, size_t val_len)
int regmap_read(struct regmap *map, uint offset, uint *valp) { - return regmap_raw_read(map, offset, valp, REGMAP_SIZE_32); + return regmap_raw_read(map, offset, valp, map->size ? map->size : REGMAP_SIZE_32); }
static inline void __write_8(u8 *addr, const u8 *val, @@ -452,7 +459,8 @@ int regmap_raw_write_range(struct regmap *map, uint range_num, uint offset, } range = &map->ranges[range_num];
- ptr = map_physmem(range->start + offset, val_len, MAP_NOCACHE); + offset <<= map->reg_offset_shift; + ptr = map_physmem(range->start + map->base_offset + offset, val_len, MAP_NOCACHE);
if (offset + val_len > range->size) { debug("%s: offset/size combination invalid\n", __func__); @@ -490,7 +498,7 @@ int regmap_raw_write(struct regmap *map, uint offset, const void *val,
int regmap_write(struct regmap *map, uint offset, uint val) { - return regmap_raw_write(map, offset, &val, REGMAP_SIZE_32); + return regmap_raw_write(map, offset, &val, map->size ? map->size : REGMAP_SIZE_32); }
int regmap_update_bits(struct regmap *map, uint offset, uint mask, uint val) diff --git a/include/regmap.h b/include/regmap.h index 2edbf9359a..4adb04f7e3 100644 --- a/include/regmap.h +++ b/include/regmap.h @@ -74,16 +74,41 @@ struct regmap_range { };
struct regmap_bus; -struct regmap_config; +/** + * struct regmap_config - a way of accessing hardware/bus registers + * + * @base_offset: Offset from the base of the regmap for reads and writes. + * (OPTIONAL) + * @reg_offset_shift: Left shift register offset by this value before + * performing reads or writes. (OPTIONAL) + * @size: Size/width of the read or write operation. Defaults to + * REGMAP_SIZE_32 if set to zero. + */ +struct regmap_config { + u32 base_offset; + u32 reg_offset_shift; + enum regmap_size_t size; +};
/** * struct regmap - a way of accessing hardware/bus registers * + * @base_offset: Offset from the base of the regmap for reads and writes. + * (OPTIONAL) + * @reg_offset_shift: Left shift register offset by this value before + * performing reads or writes. (OPTIONAL) + * @size: Size/width of the read or write operation. Defaults to + * REGMAP_SIZE_32 if set to zero. * @range_count: Number of ranges available within the map * @ranges: Array of ranges */ struct regmap { enum regmap_endianness_t endianness; + + u32 base_offset; + u32 reg_offset_shift; + enum regmap_size_t size; + int range_count; struct regmap_range ranges[0]; };