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([2600:8803:e7e4:1d00:96a3:e28:3f6:dbac]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-60646864241sm786879eaf.7.2025.04.25.09.48.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Apr 2025 09:48:52 -0700 (PDT) Message-ID: <8ea9b3b7-1896-470e-9c7e-023d4ea248bc@baylibre.com> Date: Fri, 25 Apr 2025 11:48:50 -0500 Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 3/3] iio: dac: ad3530r: Add driver for AD3530R and AD3531R To: Kim Seer Paller , Jonathan Cameron , Lars-Peter Clausen , Michael Hennerich , Rob Herring , Krzysztof Kozlowski , Conor Dooley , =?UTF-8?Q?Nuno_S=C3=A1?= , Andy Shevchenko Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org References: <20250425-togreg-v6-0-47b6f9878ae5@analog.com> <20250425-togreg-v6-3-47b6f9878ae5@analog.com> From: David Lechner Content-Language: en-US In-Reply-To: <20250425-togreg-v6-3-47b6f9878ae5@analog.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 4/25/25 7:54 AM, Kim Seer Paller wrote: > The AD3530/AD3530R (8-channel) and AD3531/AD3531R (4-channel) are > low-power, 16-bit, buffered voltage output DACs with software- > programmable gain controls, providing full-scale output spans of 2.5V or > 5V for reference voltages of 2.5V. These devices operate from a single > 2.7V to 5.5V supply and are guaranteed monotonic by design. The "R" > variants include a 2.5V, 5ppm/°C internal reference, which is disabled > by default. > > Support for monitoring internal die temperature, output voltages, and > current of a selected channel via the MUXOUT pin using an external ADC > is currently not implemented. > > Signed-off-by: Kim Seer Paller > --- Reviewed-by: David Lechner Just a few small things in the latest changes that could be improved... > +#define AD3530R_SLD_TRIG_A BIT(7) > +#define AD3530R_OUTPUT_CONTROL_RANGE BIT(2) > +#define AD3530R_REFERENCE_CONTROL_SEL BIT(0) > +#define AD3530R_REG_VAL_MASK GENMASK(15, 0) > +#define AD3530R_OP_MODE_CHAN_MSK(chan) (GENMASK(1, 0) << 2 * chan) For safety: #define AD3530R_OP_MODE_CHAN_MSK(chan) (GENMASK(1, 0) << 2 * (chan)) ... > +static ssize_t ad3530r_set_dac_powerdown(struct iio_dev *indio_dev, > + uintptr_t private, > + const struct iio_chan_spec *chan, > + const char *buf, size_t len) > +{ > + struct ad3530r_state *st = iio_priv(indio_dev); > + int ret; > + unsigned int mask, val, reg, pdmode; > + bool powerdown; > + > + ret = kstrtobool(buf, &powerdown); > + if (ret) > + return ret; > + > + guard(mutex)(&st->lock); > + mask = AD3530R_OP_MODE_CHAN_MSK(chan->channel); > + reg = chan->channel < AD3531R_MAX_CHANNELS ? > + AD3530R_OUTPUT_OPERATING_MODE_0 : > + AD3530R_OUTPUT_OPERATING_MODE_1; > + pdmode = powerdown ? st->chan[chan->channel].powerdown_mode : 0; > + val = pdmode << 2 * chan->channel; #define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask)) mask = AD3530R_OP_MODE_CHAN_MSK(chan->channel); val = field_prep(mask, pdmode); (Maybe someday this will be standardized: https://lore.kernel.org/all/cover.1739540679.git.geert+renesas@glider.be/) > + > + ret = regmap_update_bits(st->regmap, reg, mask, val); > + if (ret) > + return ret; > + > + st->chan[chan->channel].powerdown = powerdown; > + > + return len; > +} ... > +static int ad3530r_setup(struct ad3530r_state *st, int vref) > +{ > + struct device *dev = regmap_get_device(st->regmap); > + struct gpio_desc *reset_gpio; > + int i, ret; > + u8 range_multiplier, val; > + > + reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); > + if (IS_ERR(reset_gpio)) > + return dev_err_probe(dev, PTR_ERR(reset_gpio), > + "Failed to get reset GPIO\n"); > + > + if (reset_gpio) { > + /* Perform hardware reset */ > + fsleep(1 * USEC_PER_MSEC); > + gpiod_set_value_cansleep(reset_gpio, 0); > + } else { > + /* Perform software reset */ > + ret = regmap_update_bits(st->regmap, AD3530R_INTERFACE_CONFIG_A, > + AD3530R_SW_RESET, AD3530R_SW_RESET); > + if (ret) > + return ret; > + } > + > + fsleep(10 * USEC_PER_MSEC); > + > + range_multiplier = 1; > + if (device_property_read_bool(dev, "adi,range-double")) { > + ret = regmap_set_bits(st->regmap, AD3530R_OUTPUT_CONTROL_0, > + AD3530R_OUTPUT_CONTROL_RANGE); > + if (ret) > + return ret; > + > + range_multiplier = 2; > + } > + > + if (st->chip_info->internal_ref_support && vref == 0) { At this point, we've already validated that if vref == 0 then st->chip_info->internal_ref_support is true, so the check here is a bit redundant. > + ret = regmap_set_bits(st->regmap, AD3530R_REFERENCE_CONTROL_0, > + AD3530R_REFERENCE_CONTROL_SEL); > + if (ret) > + return ret; > + > + st->vref_mV = range_multiplier * AD3530R_INTERNAL_VREF_mV; > + } > + > + if (vref > 0) > + st->vref_mV = range_multiplier * vref / MILLI; And we've already validated that vref >= 0. So slightly simpler would be: if (external_vref_uV) st->vref_mV = range_multiplier * external_vref_uV / MILLI; } else { ret = regmap_set_bits(st->regmap, AD3530R_REFERENCE_CONTROL_0, AD3530R_REFERENCE_CONTROL_SEL); if (ret) return ret; st->vref_mV = range_multiplier * AD3530R_INTERNAL_VREF_mV; } (I also renamed vref to external_vref_uV to make it more obvious where the value is coming from and what the units are)