| Message ID | 1516096140-88161-1-git-send-email-preid@electromag.com.au |
|---|---|
| Headers | show |
| Series | iio: ad5272: Add support for Analog Devices digital potentiometers | expand |
On 01/16/2018 10:49 AM, Phil Reid wrote: > Add implementation for Analog Devices AD5272 and AD5274 digital > potentiometer devices. > > Signed-off-by: Phil Reid <preid@electromag.com.au> Hi, Thanks for the patch. Looks mostly good. > diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c > new file mode 100644 > index 0000000..a04b018 > --- /dev/null > +++ b/drivers/iio/potentiometer/ad5272.c > @@ -0,0 +1,227 @@ > +/* > + * Analog Devices AD5372 digital potentiometer driver > + * Copyright (C) 2018 Phil Reid <preid@electromag.com.au> > + * > + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf > + * > + * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address > + * ad5272 1 1024 20, 50, 100 01011xx > + * ad5274 1 256 20, 100 01011xx > + * > + * SPDX-License-Identifier: GPL-2.0+ People will probably complain about this, there are some weired rules where and how the SPDX identifier should be. > + */ [...] > + > +static const struct ad5272_cfg ad5272_cfg[] = { > + /* on-semiconductor parts */ Copy&paste error? > + [AD5272_020] = { .max_pos = 1024, .kohms = 20 }, > + [AD5272_050] = { .max_pos = 1024, .kohms = 50 }, > + [AD5272_100] = { .max_pos = 1024, .kohms = 100 }, > + [AD5274_020] = { .max_pos = 256, .kohms = 20, .shift = 2 }, > + [AD5274_100] = { .max_pos = 256, .kohms = 100, .shift = 2 }, > +}; [...] > + > +static int ad5272_write(struct ad5272_data *data, int reg, int val) > +{ > + u8 buf[2] = { (reg << 2) | ((val >> 8) & 0x3), (u8)val }; > + int ret; > + > + mutex_lock(&data->lock); > + ret = i2c_master_send(data->client, buf, sizeof(buf)); > + mutex_unlock(&data->lock); > + return ret < 0 ? ret : 0; > +} > + > +static int ad5272_read(struct ad5272_data *data, int reg, int *val) > +{ > + u8 buf[2] = {reg << 2, 0}; I believe the general recommendation is to not use stack based transfer buffer to avoid potential issues in case the I2C master driver uses DMA. There are many examples IIO example drivers that use DMA safe transfer buffers. Look for ____cacheline_aligned. > + int ret; > + > + mutex_lock(&data->lock); > + ret = i2c_master_send(data->client, buf, sizeof(buf)); > + if (ret < 0) > + goto error; > + > + ret = i2c_master_recv(data->client, buf, sizeof(buf)); > + if (ret < 0) > + goto error; > + This should be one I2C transfer, otherwise some other driver might get its own transfer between the send and recv, which could cause issues. > + *val = ((buf[0] & 0x3) << 8) | buf[1]; > + ret = 0; > +error: > + mutex_unlock(&data->lock); > + return ret; > +} -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
G'day Lars-Peter, On 17/01/2018 01:01, Lars-Peter Clausen wrote: > On 01/16/2018 10:49 AM, Phil Reid wrote: >> Add implementation for Analog Devices AD5272 and AD5274 digital >> potentiometer devices. >> >> Signed-off-by: Phil Reid <preid@electromag.com.au> > > Hi, > > Thanks for the patch. Looks mostly good. > >> diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c >> new file mode 100644 >> index 0000000..a04b018 >> --- /dev/null >> +++ b/drivers/iio/potentiometer/ad5272.c >> @@ -0,0 +1,227 @@ >> +/* >> + * Analog Devices AD5372 digital potentiometer driver >> + * Copyright (C) 2018 Phil Reid <preid@electromag.com.au> >> + * >> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf >> + * >> + * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address >> + * ad5272 1 1024 20, 50, 100 01011xx >> + * ad5274 1 256 20, 100 01011xx >> + * >> + * SPDX-License-Identifier: GPL-2.0+ > > People will probably complain about this, there are some weired rules where > and how the SPDX identifier should be. > Jonathan suggested this in his review of v1. Forgot to mention that in the change list. >> + */ > [...] >> + >> +static const struct ad5272_cfg ad5272_cfg[] = { >> + /* on-semiconductor parts */ > > Copy&paste error? yeap. > >> + [AD5272_020] = { .max_pos = 1024, .kohms = 20 }, >> + [AD5272_050] = { .max_pos = 1024, .kohms = 50 }, >> + [AD5272_100] = { .max_pos = 1024, .kohms = 100 }, >> + [AD5274_020] = { .max_pos = 256, .kohms = 20, .shift = 2 }, >> + [AD5274_100] = { .max_pos = 256, .kohms = 100, .shift = 2 }, >> +}; > [...] >> + >> +static int ad5272_write(struct ad5272_data *data, int reg, int val) >> +{ >> + u8 buf[2] = { (reg << 2) | ((val >> 8) & 0x3), (u8)val }; >> + int ret; >> + >> + mutex_lock(&data->lock); >> + ret = i2c_master_send(data->client, buf, sizeof(buf)); >> + mutex_unlock(&data->lock); >> + return ret < 0 ? ret : 0; >> +} >> + >> +static int ad5272_read(struct ad5272_data *data, int reg, int *val) >> +{ >> + u8 buf[2] = {reg << 2, 0}; > > I believe the general recommendation is to not use stack based transfer > buffer to avoid potential issues in case the I2C master driver uses DMA. > There are many examples IIO example drivers that use DMA safe transfer > buffers. Look for ____cacheline_aligned. ok. > >> + int ret; >> + >> + mutex_lock(&data->lock); >> + ret = i2c_master_send(data->client, buf, sizeof(buf)); >> + if (ret < 0) >> + goto error; >> + >> + ret = i2c_master_recv(data->client, buf, sizeof(buf)); >> + if (ret < 0) >> + goto error; >> + > > This should be one I2C transfer, otherwise some other driver might get its > own transfer between the send and recv, which could cause issues. Yeah I considered that. But the datasheet for the device states that a stop must be issued after the write, before the read. Docs for i2c_transfer state that the stop is issued only at the end. > >> + *val = ((buf[0] & 0x3) << 8) | buf[1]; >> + ret = 0; >> +error: >> + mutex_unlock(&data->lock); >> + return ret; >> +} > >
On Wed, 17 Jan 2018 09:46:23 +0800 Phil Reid <preid@electromag.com.au> wrote: > G'day Lars-Peter, > > On 17/01/2018 01:01, Lars-Peter Clausen wrote: > > On 01/16/2018 10:49 AM, Phil Reid wrote: > >> Add implementation for Analog Devices AD5272 and AD5274 digital > >> potentiometer devices. > >> > >> Signed-off-by: Phil Reid <preid@electromag.com.au> > > > > Hi, > > > > Thanks for the patch. Looks mostly good. > > > >> diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c > >> new file mode 100644 > >> index 0000000..a04b018 > >> --- /dev/null > >> +++ b/drivers/iio/potentiometer/ad5272.c > >> @@ -0,0 +1,227 @@ > >> +/* > >> + * Analog Devices AD5372 digital potentiometer driver > >> + * Copyright (C) 2018 Phil Reid <preid@electromag.com.au> > >> + * > >> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf > >> + * > >> + * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address > >> + * ad5272 1 1024 20, 50, 100 01011xx > >> + * ad5274 1 256 20, 100 01011xx > >> + * > >> + * SPDX-License-Identifier: GPL-2.0+ > > > > People will probably complain about this, there are some weired rules where > > and how the SPDX identifier should be. > > > Jonathan suggested this in his review of v1. Forgot to mention that in the change list. Lars is referring to the 'where' element of using SPDX tags. They go on as a c++ style comment right at the top of the file. Good think he noticed as I missed this when reviewing v3! Jonathan > > > >> + */ > > [...] > >> + > >> +static const struct ad5272_cfg ad5272_cfg[] = { > >> + /* on-semiconductor parts */ > > > > Copy&paste error? > > yeap. > > > >> + [AD5272_020] = { .max_pos = 1024, .kohms = 20 }, > >> + [AD5272_050] = { .max_pos = 1024, .kohms = 50 }, > >> + [AD5272_100] = { .max_pos = 1024, .kohms = 100 }, > >> + [AD5274_020] = { .max_pos = 256, .kohms = 20, .shift = 2 }, > >> + [AD5274_100] = { .max_pos = 256, .kohms = 100, .shift = 2 }, > >> +}; > > [...] > >> + > >> +static int ad5272_write(struct ad5272_data *data, int reg, int val) > >> +{ > >> + u8 buf[2] = { (reg << 2) | ((val >> 8) & 0x3), (u8)val }; > >> + int ret; > >> + > >> + mutex_lock(&data->lock); > >> + ret = i2c_master_send(data->client, buf, sizeof(buf)); > >> + mutex_unlock(&data->lock); > >> + return ret < 0 ? ret : 0; > >> +} > >> + > >> +static int ad5272_read(struct ad5272_data *data, int reg, int *val) > >> +{ > >> + u8 buf[2] = {reg << 2, 0}; > > > > I believe the general recommendation is to not use stack based transfer > > buffer to avoid potential issues in case the I2C master driver uses DMA. > > There are many examples IIO example drivers that use DMA safe transfer > > buffers. Look for ____cacheline_aligned. > ok. > > > > > >> + int ret; > >> + > >> + mutex_lock(&data->lock); > >> + ret = i2c_master_send(data->client, buf, sizeof(buf)); > >> + if (ret < 0) > >> + goto error; > >> + > >> + ret = i2c_master_recv(data->client, buf, sizeof(buf)); > >> + if (ret < 0) > >> + goto error; > >> + > > > > This should be one I2C transfer, otherwise some other driver might get its > > own transfer between the send and recv, which could cause issues. > > Yeah I considered that. > But the datasheet for the device states that a stop must be issued after the write, > before the read. > Docs for i2c_transfer state that the stop is issued only at the end. > > > > > > >> + *val = ((buf[0] & 0x3) << 8) | buf[1]; > >> + ret = 0; > >> +error: > >> + mutex_unlock(&data->lock); > >> + return ret; > >> +} > > > > > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 21/01/2018 20:11, Jonathan Cameron wrote: > On Wed, 17 Jan 2018 09:46:23 +0800 > Phil Reid <preid@electromag.com.au> wrote: > >> G'day Lars-Peter, >> >> On 17/01/2018 01:01, Lars-Peter Clausen wrote: >>> On 01/16/2018 10:49 AM, Phil Reid wrote: >>>> Add implementation for Analog Devices AD5272 and AD5274 digital >>>> potentiometer devices. >>>> >>>> Signed-off-by: Phil Reid <preid@electromag.com.au> >>> >>> Hi, >>> >>> Thanks for the patch. Looks mostly good. >>> >>>> diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c >>>> new file mode 100644 >>>> index 0000000..a04b018 >>>> --- /dev/null >>>> +++ b/drivers/iio/potentiometer/ad5272.c >>>> @@ -0,0 +1,227 @@ >>>> +/* >>>> + * Analog Devices AD5372 digital potentiometer driver >>>> + * Copyright (C) 2018 Phil Reid <preid@electromag.com.au> >>>> + * >>>> + * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf >>>> + * >>>> + * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address >>>> + * ad5272 1 1024 20, 50, 100 01011xx >>>> + * ad5274 1 256 20, 100 01011xx >>>> + * >>>> + * SPDX-License-Identifier: GPL-2.0+ >>> >>> People will probably complain about this, there are some weired rules where >>> and how the SPDX identifier should be. >>> >> Jonathan suggested this in his review of v1. Forgot to mention that in the change list. > Lars is referring to the 'where' element of using SPDX tags. They go > on as a c++ style comment right at the top of the file. > > Good think he noticed as I missed this when reviewing v3! > fair enough. I did grep the kernel and found a mixture of placements so just picked the wrong one. I also didn't find anything in the Documentation folder about it. But my tree isn't at the bleeding edge.
Add documentation and driver for the Analog Devices 5272. Driver currently doesn't support programing the RDAC position to non-volatile memory. Changes from v1: - Use sizeof for i2c buffer lens - Condense code a little when setting up i2c buf - check val2 in raw write - Add reset function. Perform a software reset if gpio reset pin is not defined - remove THIS_MODULE assignment - change of data to use index as per i2c device table Phil Reid (2): dt-bindings: ad5272: Add bindings for Analog Devices digital potentiometers iio: ad5272: Add support for Analog Devices digital potentiometers .../bindings/iio/potentiometer/ad5272.txt | 27 +++ drivers/iio/potentiometer/Kconfig | 10 + drivers/iio/potentiometer/Makefile | 1 + drivers/iio/potentiometer/ad5272.c | 227 +++++++++++++++++++++ 4 files changed, 265 insertions(+) create mode 100644 Documentation/devicetree/bindings/iio/potentiometer/ad5272.txt create mode 100644 drivers/iio/potentiometer/ad5272.c