Re: [PATCH v5 2/2] iio: twl6030-gpadc: TWL6030, TWL6032 GPADC driver

From: Oleksandr Kozaruk
Date: Fri Jul 19 2013 - 04:35:51 EST

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Hello Lars,

On Thu, Jul 18, 2013 at 12:48 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote:
> On 07/18/2013 10:36 AM, Oleksandr Kozaruk wrote:
>> Hello Lars,
>>
>> On Wed, Jul 17, 2013 at 9:04 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote:
>>>> +static int twl6032_calibration(struct twl6030_gpadc_data *gpadc)
>>>> +{
>>>> + int chn, d1 = 0, d2 = 0, temp;
>>>> + u8 trim_regs[17];
>>>> + int ret;
>>>> +
>>>> + ret = twl_i2c_read(TWL6030_MODULE_ID2, trim_regs + 1,
>>>> + TWL6030_GPADC_TRIM1, 16);
>>>> + if (ret < 0) {
>>>> + dev_err(gpadc->dev, "calibration failed\n");
>>>> + return ret;
>>>> + }
>>>> +
>>>> + /*
>>>> + * Loop to calculate the value needed for returning voltages from
>>>> + * GPADC not values.
>>>> + *
>>>> + * gain is calculated to 3 decimal places fixed point.
>>>> + */
>>>> + for (chn = 0; chn < TWL6032_GPADC_MAX_CHANNELS; chn++) {
>>>> +
>>>> + switch (chn) {
>>>> + case 0:
>>>> + case 1:
>>>> + case 2:
>>>> + case 3:
>>>> + case 4:
>>>> + case 5:
>>>> + case 6:
>>>> + case 11:
>>>> + case 12:
>>>> + case 13:
>>>> + case 14:
>>>> + /* D1 */
>>>> + d1 = (trim_regs[3] & 0x1F) << 2;
>>>> + d1 |= (trim_regs[1] & 0x06) >> 1;
>>>> + if (trim_regs[1] & 0x01)
>>>> + d1 = -d1;
>>>> +
>>>> + /* D2 */
>>>> + d2 = (trim_regs[4] & 0x3F) << 2;
>>>> + d2 |= (trim_regs[2] & 0x06) >> 1;
>>>> + if (trim_regs[2] & 0x01)
>>>> + d2 = -d2;
>>>> + break;
>>>> + case 8:
>>>> + /* D1 */
>>>> + temp = (trim_regs[3] & 0x1F) << 2;
>>>> + temp |= (trim_regs[1] & 0x06) >> 1;
>>>> + if (trim_regs[1] & 0x01)
>>>> + temp = -temp;
>>>> +
>>>> + d1 = (trim_regs[8] & 0x18) << 1;
>>>> + d1 |= (trim_regs[7] & 0x1E) >> 1;
>>>> + if (trim_regs[7] & 0x01)
>>>> + d1 = -d1;
>>>> +
>>>> + d1 += temp;
>>>> +
>>>> + /* D2 */
>>>> + temp = (trim_regs[4] & 0x3F) << 2;
>>>> + temp |= (trim_regs[2] & 0x06) >> 1;
>>>> + if (trim_regs[2] & 0x01)
>>>> + temp = -temp;
>>>> +
>>>> + d2 = (trim_regs[10] & 0x1F) << 2;
>>>> + d2 |= (trim_regs[8] & 0x06) >> 1;
>>>> + if (trim_regs[8] & 0x01)
>>>> + d2 = -d2;
>>>> +
>>>> + d2 += temp;
>>>> + break;
>>>> + case 9:
>>>> + /* D1 */
>>>> + temp = (trim_regs[3] & 0x1F) << 2;
>>>> + temp |= (trim_regs[1] & 0x06) >> 1;
>>>> + if (trim_regs[1] & 0x01)
>>>> + temp = -temp;
>>>> +
>>>> + d1 = (trim_regs[14] & 0x18) << 1;
>>>> + d1 |= (trim_regs[12] & 0x1E) >> 1;
>>>> + if (trim_regs[12] & 0x01)
>>>> + d1 = -d1;
>>>> +
>>>> + d1 += temp;
>>>> +
>>>> + /* D2 */
>>>> + temp = (trim_regs[4] & 0x3F) << 2;
>>>> + temp |= (trim_regs[2] & 0x06) >> 1;
>>>> + if (trim_regs[2] & 0x01)
>>>> + temp = -temp;
>>>> +
>>>> + d2 = (trim_regs[16] & 0x1F) << 2;
>>>> + d2 |= (trim_regs[14] & 0x06) >> 1;
>>>> + if (trim_regs[14] & 0x01)
>>>> + d2 = -d2;
>>>> +
>>>> + d2 += temp;
>>>> + case 10:
>>>> + /* D1 */
>>>> + d1 = (trim_regs[11] & 0x0F) << 3;
>>>> + d1 |= (trim_regs[9] & 0x0E) >> 1;
>>>> + if (trim_regs[9] & 0x01)
>>>> + d1 = -d1;
>>>> +
>>>> + /* D2 */
>>>> + d2 = (trim_regs[15] & 0x0F) << 3;
>>>> + d2 |= (trim_regs[13] & 0x0E) >> 1;
>>>> + if (trim_regs[13] & 0x01)
>>>> + d2 = -d2;
>>>> + break;
>>>> + case 7:
>>>> + case 18:
>>>> + /* D1 */
>>>> + temp = (trim_regs[3] & 0x1F) << 2;
>>>> + temp |= (trim_regs[1] & 0x06) >> 1;
>>>> + if (trim_regs[1] & 0x01)
>>>> + temp = -temp;
>>>> +
>>>> + d1 = (trim_regs[5] & 0x7E) >> 1;
>>>> + if (trim_regs[5] & 0x01)
>>>> + d1 = -d1;
>>>> +.
>>>> + d1 += temp;
>>>> +
>>>> + /* D2 */
>>>> + temp = (trim_regs[4] & 0x3F) << 2;
>>>> + temp |= (trim_regs[2] & 0x06) >> 1;
>>>> + if (trim_regs[2] & 0x01)
>>>> + temp = -temp;
>>>> +
>>>> + d2 = (trim_regs[6] & 0xFE) >> 1;
>>>> + if (trim_regs[6] & 0x01)
>>>> + d2 = -d2;
>>>> +
>>>> + d2 += temp;
>>>> + break;
>>>
>>>
>>> There is quite a bit of copy paste in here. Putting the bit swizziling into
>>> a helper function should also improbe legibility.
>>
>> Trimming bits are scattered randomly between registers and in
>> different bit positions.
>> I don't see any commonalities, that could be generalized. as Graeme
>> said about it "it's a bane of my life".
>
> The pattern is pretty regular though, how about:
>
>
> int twl6032_get_trim_value(u8 *trim_regs, unsigned int reg0,
> unsigned int reg1, unsigned int mask0, unsigned int mask1,
> unsigned int shift0)
> {
> int val;
>
> val = (trim_regs[reg0] & mask0) << shift0;
> val |= (trim_regs[reg1] & mask1) >> 1;
> if (trim_regs[reg1] & 0x01)
> val = -val;
>
> return val;
> }
>
> and then
>
> d1 = twl6032_get_trim_value(trim_regs, 3, 1, 0x1f, 0x06, 2);
> d2 = twl6032_get_trim_value(trim_regs, 4, 2, 0x3f, 0x06, 2);
>
> and so on.

Thank you. I think legibility is better now, I even found a bug - in
case 9 'break' was missing.
Though it is not without special case for channels 7, 18:
for (chn = 0; chn < TWL6032_GPADC_MAX_CHANNELS; chn++) {

switch (chn) {
case 0:
case 1:
case 2:
case 3:
case 4:
case 5:
case 6:
case 11:
case 12:
case 13:
case 14:
d1 = twl6032_get_trim_value(trim_regs, 3, 1, 0x1f, 0x06, 2);
d2 = twl6032_get_trim_value(trim_regs, 4, 2, 0x3f, 0x06, 2);
break;
case 8:
temp = twl6032_get_trim_value(trim_regs, 3, 1, 0x1f, 0x06, 2);
d1 = temp + twl6032_get_trim_value(trim_regs, 8, 7, 0x18, 0x1E, 1);

temp = twl6032_get_trim_value(trim_regs, 4, 2, 0x3F, 0x06, 2);
d2 = temp + twl6032_get_trim_value(trim_regs, 10, 8, 0x1F, 0x06, 2);
break;
case 9:
temp = twl6032_get_trim_value(trim_regs, 3, 1, 0x1f, 0x06, 2);
d1 = temp + twl6032_get_trim_value(trim_regs, 14, 12, 0x18, 0x1E, 1);

temp = twl6032_get_trim_value(trim_regs, 4, 2, 0x3f, 0x06, 2);
d2 = temp + twl6032_get_trim_value(trim_regs, 16, 14, 0x1F, 0x06, 1);
break;
case 10:
d1 = twl6032_get_trim_value(trim_regs, 11, 9, 0x0f, 0x0E, 3);
d2 = twl6032_get_trim_value(trim_regs, 15, 13, 0x0f, 0x0E, 3);
break;
case 7:
case 18:
temp = twl6032_get_trim_value(trim_regs, 3, 1, 0x1f, 0x06, 2);

d1 = (trim_regs[5] & 0x7E) >> 1;
if (trim_regs[5] & 0x01)
d1 = -d1;
d1 += temp;

temp = twl6032_get_trim_value(trim_regs, 4, 2, 0x3f, 0x06, 2);

d2 = (trim_regs[6] & 0xFE) >> 1;
if (trim_regs[6] & 0x01)
d2 = -d2;

d2 += temp;
break;
default:
/* No data for other channels */
continue;
}

--
Regards,
Oleksandr Kozaruk
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Next message: 'Maxime Ripard': "Re: [PATCH 2/3] video: hx8357: Make IM pins optional"
Previous message: Ian Campbell: "Re: [PATCH] arm: choose debug/uncompress.h include when uncompressdebug is disabled"
In reply to: Lars-Peter Clausen: "Re: [PATCH v5 2/2] iio: twl6030-gpadc: TWL6030, TWL6032 GPADC driver"
Next in thread: Oleksandr Kozaruk: "[PATCH v5 1/2] ARM: dts: twl: Add GPADC data to device tree"
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