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Date: Sat, 30 Sep 2023 15:44:34 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: David Lechner <dlechner@...libre.com>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
linux-staging@...ts.linux.dev,
David Lechner <david@...hnology.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Michael Hennerich <Michael.Hennerich@...log.com>,
Nuno Sá <nuno.sa@...log.com>,
Axel Haslam <ahaslam@...libre.com>,
Philip Molloy <pmolloy@...libre.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/27] staging: iio: resolver: ad2s1210: use
devicetree to get CLKIN rate
On Fri, 29 Sep 2023 12:23:14 -0500
David Lechner <dlechner@...libre.com> wrote:
> From: David Lechner <david@...hnology.com>
>
> From: David Lechner <dlechner@...libre.com>
>
> This removes the fclkin sysfs attribute and replaces it with getting
> the CLKIN clock rate using the clk subsystem (i.e. from the devicetree).
>
> CLKIN comes from an external oscillator that is connected directly to
> the AD2S1210 chip, so users of the sysfs attributes should not need to
> be concerned with this.
>
> The fclkin field (the datasheet name) is renamed to clkin_hz to be more
> obvious that it is a frequency in Hz.
>
> Signed-off-by: David Lechner <dlechner@...libre.com>
LGTM
Applied
J
> ---
>
> v3 changes:
> * Don't sort imports in this patch.
> * Renamed fexcit to clkin_hz.
> * Fixed ad2s1210_setup_clocks() being called in an earlier patch.
>
> drivers/staging/iio/resolver/Kconfig | 1 +
> drivers/staging/iio/resolver/ad2s1210.c | 81 ++++++++++++---------------------
> 2 files changed, 30 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/staging/iio/resolver/Kconfig b/drivers/staging/iio/resolver/Kconfig
> index 6d1e2622e0b0..bebb35822c9e 100644
> --- a/drivers/staging/iio/resolver/Kconfig
> +++ b/drivers/staging/iio/resolver/Kconfig
> @@ -7,6 +7,7 @@ menu "Resolver to digital converters"
> config AD2S1210
> tristate "Analog Devices ad2s1210 driver"
> depends on SPI
> + depends on COMMON_CLK
> depends on GPIOLIB || COMPILE_TEST
> help
> Say yes here to build support for Analog Devices spi resolver
> diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> index a710598a64f0..c8723b6f3a3b 100644
> --- a/drivers/staging/iio/resolver/ad2s1210.c
> +++ b/drivers/staging/iio/resolver/ad2s1210.c
> @@ -3,7 +3,9 @@
> * ad2s1210.c support for the ADI Resolver to Digital Converters: AD2S1210
> *
> * Copyright (c) 2010-2010 Analog Devices Inc.
> + * Copyright (c) 2023 BayLibre, SAS
> */
> +#include <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/device.h>
> #include <linux/gpio/consumer.h>
> @@ -90,7 +92,8 @@ struct ad2s1210_state {
> struct mutex lock;
> struct spi_device *sdev;
> struct gpio_desc *gpios[5];
> - unsigned int fclkin;
> + /** The external oscillator frequency in Hz. */
> + unsigned long clkin_hz;
> unsigned int fexcit;
> bool hysteresis;
> u8 resolution;
> @@ -165,7 +168,7 @@ int ad2s1210_update_frequency_control_word(struct ad2s1210_state *st)
> int ret;
> unsigned char fcw;
>
> - fcw = (unsigned char)(st->fexcit * (1 << 15) / st->fclkin);
> + fcw = (unsigned char)(st->fexcit * (1 << 15) / st->clkin_hz);
> if (fcw < AD2S1210_MIN_FCW || fcw > AD2S1210_MAX_FCW) {
> dev_err(&st->sdev->dev, "ad2s1210: FCW out of range\n");
> return -ERANGE;
> @@ -201,45 +204,6 @@ static inline int ad2s1210_soft_reset(struct ad2s1210_state *st)
> return ad2s1210_config_write(st, 0x0);
> }
>
> -static ssize_t ad2s1210_show_fclkin(struct device *dev,
> - struct device_attribute *attr,
> - char *buf)
> -{
> - struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
> -
> - return sprintf(buf, "%u\n", st->fclkin);
> -}
> -
> -static ssize_t ad2s1210_store_fclkin(struct device *dev,
> - struct device_attribute *attr,
> - const char *buf,
> - size_t len)
> -{
> - struct ad2s1210_state *st = iio_priv(dev_to_iio_dev(dev));
> - unsigned int fclkin;
> - int ret;
> -
> - ret = kstrtouint(buf, 10, &fclkin);
> - if (ret)
> - return ret;
> - if (fclkin < AD2S1210_MIN_CLKIN || fclkin > AD2S1210_MAX_CLKIN) {
> - dev_err(dev, "ad2s1210: fclkin out of range\n");
> - return -EINVAL;
> - }
> -
> - mutex_lock(&st->lock);
> - st->fclkin = fclkin;
> -
> - ret = ad2s1210_update_frequency_control_word(st);
> - if (ret < 0)
> - goto error_ret;
> - ret = ad2s1210_soft_reset(st);
> -error_ret:
> - mutex_unlock(&st->lock);
> -
> - return ret < 0 ? ret : len;
> -}
> -
> static ssize_t ad2s1210_show_fexcit(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> @@ -537,7 +501,7 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
> *val2 = 95874;
> return IIO_VAL_INT_PLUS_NANO;
> case IIO_ANGL_VEL:
> - *val = st->fclkin;
> + *val = st->clkin_hz;
> *val2 = ad2s1210_velocity_scale[st->resolution];
> return IIO_VAL_FRACTIONAL;
> default:
> @@ -549,8 +513,6 @@ static int ad2s1210_read_raw(struct iio_dev *indio_dev,
> }
> }
>
> -static IIO_DEVICE_ATTR(fclkin, 0644,
> - ad2s1210_show_fclkin, ad2s1210_store_fclkin, 0);
> static IIO_DEVICE_ATTR(fexcit, 0644,
> ad2s1210_show_fexcit, ad2s1210_store_fexcit, 0);
> static IIO_DEVICE_ATTR(control, 0644,
> @@ -599,7 +561,6 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
> };
>
> static struct attribute *ad2s1210_attributes[] = {
> - &iio_dev_attr_fclkin.dev_attr.attr,
> &iio_dev_attr_fexcit.dev_attr.attr,
> &iio_dev_attr_control.dev_attr.attr,
> &iio_dev_attr_bits.dev_attr.attr,
> @@ -657,6 +618,24 @@ static const struct iio_info ad2s1210_info = {
> .attrs = &ad2s1210_attribute_group,
> };
>
> +static int ad2s1210_setup_clocks(struct ad2s1210_state *st)
> +{
> + struct device *dev = &st->sdev->dev;
> + struct clk *clk;
> +
> + clk = devm_clk_get_enabled(dev, NULL);
> + if (IS_ERR(clk))
> + return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
> +
> + st->clkin_hz = clk_get_rate(clk);
> + if (st->clkin_hz < AD2S1210_MIN_CLKIN || st->clkin_hz > AD2S1210_MAX_CLKIN)
> + return dev_err_probe(dev, -EINVAL,
> + "clock frequency out of range: %lu\n",
> + st->clkin_hz);
> +
> + return 0;
> +}
> +
> static int ad2s1210_setup_gpios(struct ad2s1210_state *st)
> {
> struct spi_device *spi = st->sdev;
> @@ -695,6 +674,10 @@ static int ad2s1210_probe(struct spi_device *spi)
> st->resolution = 12;
> st->fexcit = AD2S1210_DEF_EXCIT;
>
> + ret = ad2s1210_setup_clocks(st);
> + if (ret < 0)
> + return ret;
> +
> ret = ad2s1210_setup_gpios(st);
> if (ret < 0)
> return ret;
> @@ -709,13 +692,7 @@ static int ad2s1210_probe(struct spi_device *spi)
> indio_dev->num_channels = ARRAY_SIZE(ad2s1210_channels);
> indio_dev->name = spi_get_device_id(spi)->name;
>
> - ret = devm_iio_device_register(&spi->dev, indio_dev);
> - if (ret)
> - return ret;
> -
> - st->fclkin = spi->max_speed_hz;
> -
> - return 0;
> + return devm_iio_device_register(&spi->dev, indio_dev);
> }
>
> static const struct of_device_id ad2s1210_of_match[] = {
>
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