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[209.132.180.67]) by mx.google.com with ESMTP id t3si3242133pfe.8.2019.05.18.02.20.32; Sat, 18 May 2019 02:20:47 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=U56U6slC; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729218AbfERIrq (ORCPT + 99 others); Sat, 18 May 2019 04:47:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:39118 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726056AbfERIrp (ORCPT ); Sat, 18 May 2019 04:47:45 -0400 Received: from archlinux (cpc91196-cmbg18-2-0-cust659.5-4.cable.virginm.net [81.96.234.148]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CDAC220872; Sat, 18 May 2019 08:47:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558169264; bh=xVQ4s+W1pGRI/yxYKXMVWLMNge7XwCa3L+oWi9nJOFY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=U56U6slCwFHle97J2KcCEMBVp2EuvNwjTujhS5G9Po497VICNcue/PbzfYI6depBk qgtJ9wm0KmNLsF4b3aHy43TV3SbcLe7pSukPDnOWSZxUdNo2k30GUThoRDnIzFIZZd NRvPV4ymRq+hmIam2hWu7ki5vvD47D1cLgKBBicg= Date: Sat, 18 May 2019 09:47:39 +0100 From: Jonathan Cameron To: Eddie James Cc: Eddie James , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, joel@jms.id.au, pmeerw@pmeerw.net, lars@metafoo.de, knaack.h@gmx.de Subject: Re: [PATCH v2 3/3] iio: dps310: Add pressure sensing capability Message-ID: <20190518094739.45d3a912@archlinux> In-Reply-To: References: <1557344128-690-1-git-send-email-eajames@linux.ibm.com> <1557344128-690-4-git-send-email-eajames@linux.ibm.com> <20190511104822.304a1ead@archlinux> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 May 2019 15:25:55 -0500 Eddie James wrote: > On 5/11/19 4:48 AM, Jonathan Cameron wrote: > > On Wed, 8 May 2019 14:35:28 -0500 > > Eddie James wrote: > > =20 > >> The DPS310 supports measurement of pressure, so support that in the > >> driver. Use background measurement like the temperature sensing and > >> default to lowest precision and lowest measurement rate. > >> > >> Signed-off-by: Eddie James =20 > > Hi Eddie, > > > > A few comments inline. One is around how you might look at adding > > fifo support (pushing to an IIO buffer) in the future... The IIO > > data model isn't as flexible as this device can be, so we may need > > to put some restrictions on combinations of options. > > > > Jonathan =20 > >> --- > >> drivers/iio/pressure/dps310.c | 331 ++++++++++++++++++++++++++++++++= +++++++--- > >> 1 file changed, 307 insertions(+), 24 deletions(-) > >> > >> diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps3= 10.c > >> index c42808e..a7ee28c 100644 > >> --- a/drivers/iio/pressure/dps310.c > >> +++ b/drivers/iio/pressure/dps310.c > >> @@ -11,11 +11,11 @@ > >> * c0 * 0.5 + c1 * T_raw / kT =C2=B0C > >> * > >> * TODO: > >> - * - Pressure sensor readings > >> * - Optionally support the FIFO > >> */ > >> =20 > >> #include > >> +#include > >> #include > >> #include > >> =20 > >> @@ -29,6 +29,8 @@ > >> #define DPS310_TMP_B1 0x04 > >> #define DPS310_TMP_B2 0x05 > >> #define DPS310_PRS_CFG 0x06 > >> +#define DPS310_PRS_RATE_BITS GENMASK(6, 4) > >> +#define DPS310_PRS_PRC_BITS GENMASK(3, 0) > >> #define DPS310_TMP_CFG 0x07 > >> #define DPS310_TMP_RATE_BITS GENMASK(6, 4) > >> #define DPS310_TMP_PRC_BITS GENMASK(3, 0) > >> @@ -82,6 +84,8 @@ struct dps310_data { > >> struct regmap *regmap; > >> =20 >=20 > >> + > >> static bool dps310_is_writeable_reg(struct device *dev, unsigned int= reg) > >> { > >> switch (reg) { > >> @@ -253,24 +387,141 @@ static int dps310_write_raw(struct iio_dev *iio, > >> { > >> struct dps310_data *data =3D iio_priv(iio); > >> =20 > >> - if (chan->type !=3D IIO_TEMP) > >> + switch (mask) { > >> + case IIO_CHAN_INFO_SAMP_FREQ: > >> + switch (chan->type) { > >> + case IIO_PRESSURE: > >> + return dps310_set_pres_samp_freq(data, val); > >> + > >> + case IIO_TEMP: > >> + return dps310_set_temp_samp_freq(data, val); =20 > > This may need a bit of thought if there is any chance we will later sup= port > > the fifo. > > > > The IIO model is that of scans that read all channels at each 'trigger'= . In > > devices like this which allow for different sampling rates for differen= t sensor > > channels there are two options. > > > > 1) Don't support it. > > 2) Deal with registering two separate IIO devices and do the demux in t= he > > driver to the relevant one. > > > > All depends on whether there is a substantial usecase for different sam= pling > > rates or not. Here I suspect the answer is not. > > > > The complexity is that, you then need to work out how to 'upgrade' the > > interface when buffered support is added. Obvious options are: > > > > 1) Refuse to move to buffered mode if the sampling frequencies are diff= erent. > > 2) Force the slower channel to be sampled faster if that is possible. > > 3) Change to only having one exposed sampling frequency at all - the pr= oblem > > with this last one is that it changes the ABI for existing users. > > > > It may be no one ever cares about the fifo mode though as high speed pr= essure > > measurement is 'unusual' ;) =20 >=20 >=20 > Thanks for the comments Jonathan. I will follow your suggestions=20 > throughout the driver. >=20 > The sampling rates are a bit confusing for me, and I haven't looked into= =20 > the buffered mode at all. Are you saying that in the current form, it=20 > won't work to use different sampling frequencies for the two sensors=20 > (without buffered mode I mean)? I haven't noticed any problems in my=20 > tests. I'm inclined force the slower channel to be sampled faster if=20 > necessary when buffered mode is implemented. That would be a 'slightly' interesting interpretation of the ABI, but I'd 'probably' let it go as any correct userspace should be fine receiving data at a higher rate than it asked for. Jonathan >=20 > Thanks, >=20 > Eddie >=20 >=20 > > =20 > >> + > >> + default: > >> + return -EINVAL; > >> + } > >> + > >> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO: > >> + switch (chan->type) { > >> + case IIO_PRESSURE: > >> + return dps310_set_pres_precision(data, val); > >> + > >> + case IIO_TEMP: > >> + return dps310_set_temp_precision(data, val); > >> + > >> + default: > >> + return -EINVAL; > >> + } > >> + > >> + default: > >> return -EINVAL; > >> + } > >> +} > >> + > >> +static int dps310_calculate_pressure(struct dps310_data *data) > >> +{ > >> + int i, r, t_ready; > >> + int kpi =3D dps310_get_pres_k(data); > >> + int kti =3D dps310_get_temp_k(data); > >> + s64 rem =3D 0ULL; > >> + s64 pressure =3D 0ULL; > >> + s64 p; > >> + s64 t; > >> + s64 denoms[7]; > >> + s64 nums[7]; > >> + s64 rems[7]; > >> + s64 kp; > >> + s64 kt; > >> + > >> + if (kpi < 0) > >> + return kpi; > >> + > >> + if (kti < 0) > >> + return kti; > >> + > >> + kp =3D (s64)kpi; > >> + kt =3D (s64)kti; > >> + > >> + /* Refresh temp if it's ready, otherwise just use the latest value */ > >> + r =3D regmap_read(data->regmap, DPS310_MEAS_CFG, &t_ready); > >> + if (r >=3D 0 && t_ready & DPS310_TMP_RDY) > >> + dps310_read_temp_ready(data); > >> + > >> + p =3D (s64)data->pressure_raw; > >> + t =3D (s64)data->temp_raw; > >> + > >> + /* Section 4.9.1 of the DPS310 spec; algebra'd to avoid underflow */ > >> + nums[0] =3D (s64)data->c00; > >> + denoms[0] =3D 1LL; > >> + nums[1] =3D p * (s64)data->c10; > >> + denoms[1] =3D kp; > >> + nums[2] =3D p * p * (s64)data->c20; > >> + denoms[2] =3D kp * kp; > >> + nums[3] =3D p * p * p * (s64)data->c30; > >> + denoms[3] =3D kp * kp * kp; > >> + nums[4] =3D t * (s64)data->c01; > >> + denoms[4] =3D kt; > >> + nums[5] =3D t * p * (s64)data->c11; > >> + denoms[5] =3D kp * kt; > >> + nums[6] =3D t * p * p * (s64)data->c21; > >> + denoms[6] =3D kp * kp * kt; > >> + > >> + /* Kernel lacks a div64_s64_rem function; denoms are all positive */ > >> + for (i =3D 0; i < 7; ++i) { > >> + u64 rem; > >> + > >> + if (nums[i] < 0LL) { > >> + pressure -=3D div64_u64_rem(-nums[i], denoms[i], &rem); > >> + rems[i] =3D -rem; > >> + } else { > >> + pressure +=3D div64_u64_rem(nums[i], denoms[i], &rem); > >> + rems[i] =3D (s64)rem; > >> + } > >> + } > >> + > >> + /* Increase precision and calculate the remainder sum */ > >> + for (i =3D 0; i < 7; ++i) > >> + rem +=3D div64_s64((s64)rems[i] * 1000000000LL, denoms[i]); > >> + > >> + pressure +=3D div_s64(rem, 1000000000LL); > >> + > >> + return (int)pressure; > >> +} > >> + > >> +static int dps310_read_pressure(struct dps310_data *data, int *val, i= nt *val2, > >> + long mask) > >> +{ > >> + int ret; > >> =20 > >> switch (mask) { > >> case IIO_CHAN_INFO_SAMP_FREQ: > >> - return dps310_set_temp_samp_freq(data, val); > >> + *val =3D dps310_get_pres_samp_freq(data); > >> + return IIO_VAL_INT; > >> + > >> + case IIO_CHAN_INFO_RAW: > >> + ret =3D dps310_read_pres_raw(data); > >> + if (ret) > >> + return ret; > >> + > >> + *val =3D dps310_calculate_pressure(data); =20 > > This is rather far from raw :) It might be better at this point to just > > go for PROCESSED and apply the scale in here. > > =20 > >> + return IIO_VAL_INT; > >> + > >> + case IIO_CHAN_INFO_SCALE: > >> + *val =3D 1; > >> + *val2 =3D 1000; /* Convert Pa to KPa per IIO ABI */ > >> + return IIO_VAL_FRACTIONAL; > >> + > >> case IIO_CHAN_INFO_OVERSAMPLING_RATIO: > >> - return dps310_set_temp_precision(data, val); > >> + *val =3D dps310_get_pres_precision(data); > >> + return IIO_VAL_INT; > >> + > >> default: > >> return -EINVAL; > >> } > >> } > >> =20 > >> -static int dps310_read_raw(struct iio_dev *iio, > >> - struct iio_chan_spec const *chan, > >> - int *val, int *val2, long mask) > >> +static int dps310_read_temp(struct dps310_data *data, int *val, int *= val2, > >> + long mask) > >> { > >> - struct dps310_data *data =3D iio_priv(iio); > >> int ret; > >> =20 > >> switch (mask) { > >> @@ -279,7 +530,7 @@ static int dps310_read_raw(struct iio_dev *iio, > >> return IIO_VAL_INT; > >> =20 > >> case IIO_CHAN_INFO_RAW: > >> - ret =3D dps310_read_temp(data); > >> + ret =3D dps310_read_temp_raw(data); > >> if (ret) > >> return ret; > >> =20 > >> @@ -312,6 +563,24 @@ static int dps310_read_raw(struct iio_dev *iio, > >> } > >> } > >> =20 > >> +static int dps310_read_raw(struct iio_dev *iio, > >> + struct iio_chan_spec const *chan, > >> + int *val, int *val2, long mask) > >> +{ > >> + struct dps310_data *data =3D iio_priv(iio); > >> + > >> + switch (chan->type) { > >> + case IIO_PRESSURE: > >> + return dps310_read_pressure(data, val, val2, mask); > >> + > >> + case IIO_TEMP: > >> + return dps310_read_temp(data, val, val2, mask); > >> + > >> + default: > >> + return -EINVAL; > >> + } > >> +} > >> + > >> static const struct regmap_config dps310_regmap_config =3D { > >> .reg_bits =3D 8, > >> .val_bits =3D 8, > >> @@ -393,6 +662,13 @@ static int dps310_probe(struct i2c_client *client, > >> return PTR_ERR(data->regmap); > >> =20 > >> /* > >> + * Set up pressure sensor in single sample, one measurement per seco= nd > >> + * mode > >> + */ > >> + r =3D regmap_write(data->regmap, DPS310_PRS_CFG, > >> + DPS310_CALC_RATE(1) | DPS310_CALC_PRC(1)); > >> + > >> + /* > >> * Set up external (MEMS) temperature sensor in single sample, one > >> * measurement per second mode > >> */ > >> @@ -402,16 +678,23 @@ static int dps310_probe(struct i2c_client *clien= t, > >> if (r < 0) > >> goto err; > >> =20 > >> - /* Temp shift is disabled when PRC <=3D 8 */ > >> + /* Temp and pressure shifts are disabled when PRC <=3D 8 */ > >> r =3D regmap_write_bits(data->regmap, DPS310_CFG_REG, > >> - DPS310_TMP_SHIFT_EN, 0); > >> + DPS310_TMP_SHIFT_EN | DPS310_PRS_SHIFT_EN, 0); > >> + if (r < 0) > >> + goto err; > >> + > >> + /* MEAS_CFG doesn't seem to update unless first written with 0 */ > >> + r =3D regmap_write_bits(data->regmap, DPS310_MEAS_CFG, > >> + DPS310_MEAS_CTRL_BITS, 0); > >> if (r < 0) > >> goto err; > >> =20 > >> - /* Turn on temperature measurement in the background */ > >> + /* Turn on temperature and pressure measurement in the background */ > >> r =3D regmap_write_bits(data->regmap, DPS310_MEAS_CFG, > >> DPS310_MEAS_CTRL_BITS, > >> - DPS310_TEMP_EN | DPS310_BACKGROUND); > >> + DPS310_PRS_EN | DPS310_TEMP_EN | > >> + DPS310_BACKGROUND); > >> if (r < 0) > >> goto err; > >> =20 > >> @@ -424,7 +707,7 @@ static int dps310_probe(struct i2c_client *client, > >> if (r < 0) > >> goto err; > >> =20 > >> - r =3D dps310_get_temp_coef(data); > >> + r =3D dps310_get_coefs(data); > >> if (r < 0) > >> goto err; > >> =20 >=20