Hi,
Am 10.04.2018 um 16:41 schrieb Andy Shevchenko andy.shevchenko@gmail.com:
On Wed, Apr 4, 2018 at 10:00 PM, H. Nikolaus Schaller hns@goldelico.com wrote:
PCAL chips ("L" seems to stand for "latched") have additional registers starting at address 0x40 to control the latches, interrupt mask, pull-up and pull down etc.
The constants are so far defined in a way that they fit for the pcal9555a when shifted by the number of banks, i.e. multiplied by 2.
Now the pcal6524 has 3 banks which means the relative offset must be multiplied by 4 which gives a wrong result if not done carefully, since the base offset is already included in the offset.
For the basic registers shared with all pca93xx/tca64xx chips there is no such offset.
Therefore, we add code to adjust the register number for exended registers in this case.
And we add additional register offset constants (not yet used by the driver code) which are specific to the pcal6524.
-#define PCAL953X_IN_LATCH 34 -#define PCAL953X_INT_MASK 37 -#define PCAL953X_INT_STAT 38
I prefer either to change first all the rest to be 2 digit hex values first, or leave decimal in this patch.
Ok, let's change them all to hex (like in the data sheets).
+#define PCAL953X_OUT_STRENGTH 0x20 +#define PCAL953X_IN_LATCH 0x22 +#define PCAL953X_PULL_EN 0x23 +#define PCAL953X_PULL_SEL 0x24 +#define PCAL953X_INT_MASK 0x25 +#define PCAL953X_INT_STAT 0x26 +#define PCAL953X_OUT_CONF 0x27
+#define PCAL6524_INT_EDGE 0x28 +#define PCAL6524_INT_CLR 0x2a +#define PCAL6524_IN_STATUS 0x2b +#define PCAL6524_OUT_INDCONF 0x2c +#define PCAL6524_DEBOUNCE 0x2d
/* adjust register address for pcal6524 */if (reg >= PCAL953X_OUT_STRENGTH)reg -= PCAL953X_OUT_STRENGTH >> 1;I don't like this condition. Can we avoid relying on the register offset in regard to some flag / compatible string / etc?
I don't think so.
for TCA6416 and PCAL9555 the real registers are e.g.: PCA953X_INPUT 0x00 / 0x01 PCA953X_OUTPUT 0x02 / 0x03
i.e. every address constant is shifted left 1 bit in the 16 bit accessors.
for PCAL9555 some extended registers:
PCAL953X_OUT_STRENGTH 0x40 / 0x41 / 0x42 / 0x43 PCAL953X_IN_LATCH 0x44 / 0x45
i.e. PCAL953X_IN_LATCH is also simply shifted left by 1 bit because the extended constants are defined that they fit.
for TCA6424 and PCAL6524: PCA953X_INPUT 0x00 / 0x01 / 0x02 PCA953X_OUTPUT 0x04 / 0x05 / 0x06
every address is shifted left 2 bits in the 24 bit accessors.
for PCAL6524: PCAL953X_OUT_STRENGTH 0x40 / 0x41 / 0x42 / 0x43 / 0x44 / 0x45 PCAL953X_IN_LATCH 0x48 / 0x49 / 0x4a
simply shifting left by 2 bits gives wrong result which is this special case. It is not a general chip property but a mix of chip bit-width and depends on accessing the first or second bank.
So the full condition to apply this address fix is:
if (24 bit access && second bank access) do correction.
and it can be simplified to what I suggest, because the 8/16/24 bit accessors are already separate functions.
I don't think this can't be hard-coded into flags / compatible string.
/* adjust register address for pcal6524 */if (reg >= PCAL953X_OUT_STRENGTH)reg -= PCAL953X_OUT_STRENGTH >> 1;Ditto.
-- With Best Regards, Andy Shevchenko
BR and thanks, Nikolaus