| Message ID | 20240117125124.8326-1-mitrutzceclan@gmail.com |
|---|---|
| Headers | show |
| Series | Add support for LTC6373 | expand |
On Wed, 17 Jan 2024 14:51:13 +0200 Dumitru Ceclan <mitrutzceclan@gmail.com> wrote: > Change the match table to use pointers instead of device ids. > Alignment of the hmc425a_state was changed because of the const > specifier for hmc425a_chip_info. > > Signed-off-by: Dumitru Ceclan <mitrutzceclan@gmail.com> Hi Dumitru The remaining use of type in here and deriving from structure offsets is not nice. Add a trivial callback for the stuff in write_raw() that needs to be different and is currently in a switch statement. Then get rid of the type enum completely if possible. > --- > drivers/iio/amplifiers/hmc425a.c | 39 ++++++++++++++++++-------------- > 1 file changed, 22 insertions(+), 17 deletions(-) > > diff --git a/drivers/iio/amplifiers/hmc425a.c b/drivers/iio/amplifiers/hmc425a.c > index e1162a500daf..b116b54e4206 100644 > --- a/drivers/iio/amplifiers/hmc425a.c > +++ b/drivers/iio/amplifiers/hmc425a.c > @@ -37,11 +37,11 @@ struct hmc425a_chip_info { > }; > > struct hmc425a_state { > - struct mutex lock; /* protect sensor state */ > - struct hmc425a_chip_info *chip_info; > - struct gpio_descs *gpios; > - enum hmc425a_type type; > - u32 gain; > + struct mutex lock; /* protect sensor state */ > + const struct hmc425a_chip_info *chip_info; > + struct gpio_descs *gpios; > + enum hmc425a_type type; > + u32 gain; This illustrates why I'm not keen on manual alignment like this. Generates churn that makes it hard to spot the actual changes. To avoid this happening again I'd suggest a single space is fine for all lines and don't align them at all! > }; > > static int hmc425a_write(struct iio_dev *indio_dev, u32 value) > @@ -58,7 +58,7 @@ static int hmc425a_write(struct iio_dev *indio_dev, u32 value) > > static int hmc425a_gain_dB_to_code(struct hmc425a_state *st, int val, int val2, int *code) > { > - struct hmc425a_chip_info *inf = st->chip_info; > + const struct hmc425a_chip_info *inf = st->chip_info; > int gain, temp; > > if (val < 0) > @@ -187,15 +187,6 @@ static const struct iio_chan_spec hmc425a_channels[] = { > HMC425A_CHAN(0), > }; > > -/* Match table for of_platform binding */ > -static const struct of_device_id hmc425a_of_match[] = { > - { .compatible = "adi,hmc425a", .data = (void *)ID_HMC425A }, > - { .compatible = "adi,hmc540s", .data = (void *)ID_HMC540S }, > - { .compatible = "adi,adrf5740", .data = (void *)ID_ADRF5740 }, > - {}, > -}; > -MODULE_DEVICE_TABLE(of, hmc425a_of_match); > - > static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = { > [ID_HMC425A] = { > .name = "hmc425a", > @@ -226,6 +217,18 @@ static struct hmc425a_chip_info hmc425a_chip_info_tbl[] = { > }, > }; > > +/* Match table for of_platform binding */ > +static const struct of_device_id hmc425a_of_match[] = { > + { .compatible = "adi,hmc425a", > + .data = &hmc425a_chip_info_tbl[ID_HMC425A]}, > + { .compatible = "adi,hmc540s", > + .data = &hmc425a_chip_info_tbl[ID_HMC540S]}, > + { .compatible = "adi,adrf5740", > + .data = &hmc425a_chip_info_tbl[ID_ADRF5740]}, > + {}, Nice to drop that trailing comma whilst here. No need for one on a 'terminator' of such an array as by definition nothing should ever be added after it. > +}; > +MODULE_DEVICE_TABLE(of, hmc425a_of_match); > + > static int hmc425a_probe(struct platform_device *pdev) > { > struct iio_dev *indio_dev; > @@ -237,14 +240,16 @@ static int hmc425a_probe(struct platform_device *pdev) > return -ENOMEM; > > st = iio_priv(indio_dev); > - st->type = (uintptr_t)device_get_match_data(&pdev->dev); > > - st->chip_info = &hmc425a_chip_info_tbl[st->type]; > + st->chip_info = device_get_match_data(&pdev->dev); > indio_dev->num_channels = st->chip_info->num_channels; > indio_dev->channels = st->chip_info->channels; > indio_dev->name = st->chip_info->name; > st->gain = st->chip_info->default_gain; > > + /* Compute index of the acquired chip info in the array */ > + st->type = st->chip_info - hmc425a_chip_info_tbl; Definitely not a good idea. If you need a type field, put it in the chip_info_tbl but you should not need one anyway because type is rarely what matters but rather data or behavior (via a callback) needed for a given device. Here it looks like a callback is needed for the few lines in write_raw() that are fiddly to express as data. > + > st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl", GPIOD_OUT_LOW); > if (IS_ERR(st->gpios)) > return dev_err_probe(&pdev->dev, PTR_ERR(st->gpios),
On Wed, 17 Jan 2024 14:51:12 +0200 Dumitru Ceclan <mitrutzceclan@gmail.com> wrote: > Move gain-dB<->code conversion logic from read_raw and write_raw to > hmc425a_gain_dB_to_code() and hmc425a_code_to_gain_dB(). > > Signed-off-by: Dumitru Ceclan <mitrutzceclan@gmail.com> Some comments inline Jonathan > --- > drivers/iio/amplifiers/hmc425a.c | 102 ++++++++++++++++++------------- > 1 file changed, 59 insertions(+), 43 deletions(-) > > diff --git a/drivers/iio/amplifiers/hmc425a.c b/drivers/iio/amplifiers/hmc425a.c > index ed4d72922696..e1162a500daf 100644 > --- a/drivers/iio/amplifiers/hmc425a.c > +++ b/drivers/iio/amplifiers/hmc425a.c > @@ -56,35 +56,72 @@ static int hmc425a_write(struct iio_dev *indio_dev, u32 value) > return 0; > } > > +static int hmc425a_gain_dB_to_code(struct hmc425a_state *st, int val, int val2, int *code) > +{ > + struct hmc425a_chip_info *inf = st->chip_info; > + int gain, temp; > + > + if (val < 0) > + gain = (val * 1000) - (val2 / 1000); > + else > + gain = (val * 1000) + (val2 / 1000); > + > + if (gain > inf->gain_max || gain < inf->gain_min) > + return -EINVAL; > + > + switch (st->type) { > + case ID_HMC425A: > + *code = ~((abs(gain) / 500) & 0x3F); In the next patch I point out that this should be data or callbacks in in the st->chip_info structure, not encoded in code here based on st->type (which I want you to get rid of!) > + return 0; > + case ID_HMC540S: > + *code = ~((abs(gain) / 1000) & 0xF); > + return 0; > + case ID_ADRF5740: > + temp = (abs(gain) / 2000) & 0xF; > + *code = temp & BIT(3) ? temp | BIT(2) : temp; Given you are moving the code, a comment here might be nice as it's unusual (bits are 2DB, 4DB, 8DB and another 8DB) > + return 0; > + default: > + return -EINVAL; > + } > +} > + > +static int hmc425a_code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2) > +{ > + int code, gain; > + > + code = st->gain; > + switch (st->type) { > + case ID_HMC425A: > + gain = ~code * -500; > + break; > + case ID_HMC540S: > + gain = ~code * -1000; > + break; > + case ID_ADRF5740: > + code = code & BIT(3) ? code & ~BIT(2) : code; > + gain = code * -2000; > + break; > + } > + > + *val = gain / 1000; > + *val2 = (gain % 1000) * 1000; > + > + return 0; > +} > + > static int hmc425a_read_raw(struct iio_dev *indio_dev, > struct iio_chan_spec const *chan, int *val, > int *val2, long m) > { > struct hmc425a_state *st = iio_priv(indio_dev); > - int code, gain = 0; > int ret; > > mutex_lock(&st->lock); > switch (m) { > case IIO_CHAN_INFO_HARDWAREGAIN: > - code = st->gain; > - > - switch (st->type) { > - case ID_HMC425A: > - gain = ~code * -500; > - break; > - case ID_HMC540S: > - gain = ~code * -1000; > + ret = hmc425a_code_to_gain_dB(st, val, val2); > + if (ret) > break; > - case ID_ADRF5740: > - code = code & BIT(3) ? code & ~BIT(2) : code; > - gain = code * -2000; > - break; > - } > - > - *val = gain / 1000; > - *val2 = (gain % 1000) * 1000; > - > ret = IIO_VAL_INT_PLUS_MICRO_DB; > break; > default: > @@ -100,36 +137,15 @@ static int hmc425a_write_raw(struct iio_dev *indio_dev, > int val2, long mask) > { > struct hmc425a_state *st = iio_priv(indio_dev); > - struct hmc425a_chip_info *inf = st->chip_info; > - int code = 0, gain; > - int ret; > - > - if (val < 0) > - gain = (val * 1000) - (val2 / 1000); > - else > - gain = (val * 1000) + (val2 / 1000); > - > - if (gain > inf->gain_max || gain < inf->gain_min) > - return -EINVAL; > - > - switch (st->type) { > - case ID_HMC425A: > - code = ~((abs(gain) / 500) & 0x3F); > - break; > - case ID_HMC540S: > - code = ~((abs(gain) / 1000) & 0xF); > - break; > - case ID_ADRF5740: > - code = (abs(gain) / 2000) & 0xF; > - code = code & BIT(3) ? code | BIT(2) : code; > - break; > - } > + int code = 0, ret; > > mutex_lock(&st->lock); > switch (mask) { > case IIO_CHAN_INFO_HARDWAREGAIN: > + ret = hmc425a_gain_dB_to_code(st, val, val2, &code); > + if (ret) > + break; > st->gain = code; > - > ret = hmc425a_write(indio_dev, st->gain); > break; > default:
On Wed, 17 Jan 2024 14:51:14 +0200 Dumitru Ceclan <mitrutzceclan@gmail.com> wrote: > This adds support for LTC6373 36 V Fully-Differential Programmable-Gain > Instrumentation Amplifier with 25 pA Input Bias Current. > The user can program the gain to one of seven available settings through > a 3-bit parallel interface (A2 to A0). > > Signed-off-by: Dumitru Ceclan <mitrutzceclan@gmail.com> Hi Dumitru, Some comments inline. I'd forgotten we have a rich set of DIV_xxx macros in math.h, DIV_ROUND_CLOSEST is I think the same as what you have coded up in here. > --- > drivers/iio/amplifiers/hmc425a.c | 118 +++++++++++++++++++++++++++++-- > 1 file changed, 114 insertions(+), 4 deletions(-) > > diff --git a/drivers/iio/amplifiers/hmc425a.c b/drivers/iio/amplifiers/hmc425a.c > index b116b54e4206..e7f425677fd3 100644 > --- a/drivers/iio/amplifiers/hmc425a.c > +++ b/drivers/iio/amplifiers/hmc425a.c > @@ -2,9 +2,10 @@ > /* > * HMC425A and similar Gain Amplifiers > * > - * Copyright 2020 Analog Devices Inc. > + * Copyright 2020, 2023 Analog Devices Inc. > */ > > +#include <linux/bits.h> > #include <linux/bitops.h> > #include <linux/device.h> > #include <linux/err.h> > @@ -20,10 +21,24 @@ > #include <linux/regulator/consumer.h> > #include <linux/sysfs.h> > > +/* > + * The LTC6373 amplifier supports configuring gain using GPIO's with the following > + * values (OUTPUT_V / INPUT_V): 0(shutdown), 0.25, 0.5, 1, 2, 4, 8, 16 > + * > + * Except for the shutdown value, all can be converted to dB using 20 * log10(x) > + * From here, it is observed that all values are multiples of the '2' gain setting, > + * with the correspondent of 6.020dB. > + */ > +#define LTC6373_CONVERSION_CONSTANT 6020 > +#define LTC6373_MIN_GAIN_CODE 0x6 > +#define LTC6373_CONVERSION_MASK GENMASK(2, 0) > +#define LTC6373_SHUTDOWN GENMASK(2, 0) > + > enum hmc425a_type { > ID_HMC425A, > ID_HMC540S, > - ID_ADRF5740 > + ID_ADRF5740, > + ID_LTC6373, > }; > > struct hmc425a_chip_info { > @@ -34,6 +49,8 @@ struct hmc425a_chip_info { > int gain_min; > int gain_max; > int default_gain; > + int powerdown_val; > + bool has_powerdown; > }; > > struct hmc425a_state { > @@ -42,6 +59,7 @@ struct hmc425a_state { > struct gpio_descs *gpios; > enum hmc425a_type type; > u32 gain; > + bool powerdown; > }; > > static int hmc425a_write(struct iio_dev *indio_dev, u32 value) > @@ -80,6 +98,17 @@ static int hmc425a_gain_dB_to_code(struct hmc425a_state *st, int val, int val2, > temp = (abs(gain) / 2000) & 0xF; > *code = temp & BIT(3) ? temp | BIT(2) : temp; > return 0; > + case ID_LTC6373: > + if (st->powerdown) > + return -EPERM; > + > + /* add half of the value for rounding */ > + temp = LTC6373_CONVERSION_CONSTANT / 2; As mentioned in review of earlier patch, I'd like this to be in a callback not based on st->type (which should be removed from the driver). > + if (val < 0) > + temp *= -1; > + *code = ~((gain + temp) / LTC6373_CONVERSION_CONSTANT + 3) I'd forgotten in previous reviews that we have DIV_ROUND_CLOSEST() that does pretty similar maths to your handling here. Better to use that than spin your own version. > + & LTC6373_CONVERSION_MASK; > + return 0; > default: > return -EINVAL; > } > @@ -101,6 +130,12 @@ static int hmc425a_code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2 > code = code & BIT(3) ? code & ~BIT(2) : code; > gain = code * -2000; > break; > + case ID_LTC6373: > + if (st->powerdown) > + return -EPERM; > + gain = ((~code & LTC6373_CONVERSION_MASK) - 3) * > + LTC6373_CONVERSION_CONSTANT; > + break; > } > > *val = gain / 1000; > @@ -174,6 +209,48 @@ static const struct iio_info hmc425a_info = { > .write_raw_get_fmt = &hmc425a_write_raw_get_fmt, > }; > > + > +static const struct iio_chan_spec_ext_info ltc6373_ext_info[] = { > + { > + .name = "powerdown", > + .read = ltc6373_read_powerdown, > + .write = ltc6373_write_powerdown, > + .shared = IIO_SEPARATE, > + }, > + {}, No comma preferred after a terminator entry like this as nothing should ever come after it. Any new additions must be before this last entry. > +};
hello Dumitru, I know this is not part of your current patch, but you might also want to have a look at ltc6373_write_powerdown(): hmc425a.c:239:2: warning: Value stored to 'ret' is never read [deadcode.DeadStores] 239 | ret = hmc425a_write(indio_dev, code); cheers, peter
This patch series adds support for the LTC6373 Instrumentation Amplifier within the existing HMC425A driver. The LTC6373 is a silicon, 3-bit Fully-Differential digital instrumentation amplifier that supports the following programmable gains (Vout/Vin): G = 0.25, 0.5, 1, 2, 4, 8, 16 + Shutdown. The programmable interface consists of 3 digitally controled inputs. V3->V4 - Fix git commit message typo and remove newline between tags V2->V3 - Use return instead of break in *_gain_dB_to_code() - Add new line before return in *_code_to_gain_dB() - Match parameter alignment for added _powerdown functions - Add precursor patch for using pointers in the match table - Add chip_info attributes: has_powerdown and powerdown_val - Change probe logic to use has_powerdown for default powerdown state - Added 'Fixes' tag to commit message of 'add conditional GPIO array...' V1->V2 Driver: - Fix chip info table indent - Remove enable attribute - Add ext_info powerdown attribute - Enable by default powerdown attribute - Set default gain after disabling powerdown to min value Binding: - Fix conditional checking of GPIO array size for LTC6373 - Add precursor commit for correctly checking gpio size depending upon compatible Dumitru Ceclan (5): dt-bindings: iio: hmc425a: add conditional GPIO array size constraints dt-bindings: iio: hmc425a: add entry for LTC6373 iio: amplifiers: hmc425a: move conversion logic iio: amplifiers: hmc425a: use pointers in match table iio: amplifiers: hmc425a: add support for LTC6373 Instrumentation Amplifier .../bindings/iio/amplifiers/adi,hmc425a.yaml | 47 +++- drivers/iio/amplifiers/hmc425a.c | 253 +++++++++++++----- 2 files changed, 236 insertions(+), 64 deletions(-)