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Date: Fri, 07 Jun 2024 13:08:30 +0200
From: Nuno Sá <noname.nuno@...il.com>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>, Lars-Peter Clausen
<lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>,
Jonathan Cameron
<jic23@...nel.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
<krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] iio: frequency: adf4350: add clk provider
On Fri, 2024-06-07 at 12:57 +0300, Antoniu Miclaus wrote:
> Add clk provider feature for the adf4350.
>
> Even though the driver was sent as an IIO driver in most cases the
> device is actually seen as a clock provider.
>
> This patch aims to cover actual usecases requested by users in order to
> completely control the output frequencies from userspace.
>
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
> ---
> changes in v2:
> - rework commit title
> drivers/iio/frequency/adf4350.c | 129 ++++++++++++++++++++++++++++++++
> 1 file changed, 129 insertions(+)
>
> diff --git a/drivers/iio/frequency/adf4350.c b/drivers/iio/frequency/adf4350.c
> index 4abf80f75ef5..1eb8bce71fe1 100644
> --- a/drivers/iio/frequency/adf4350.c
> +++ b/drivers/iio/frequency/adf4350.c
> @@ -19,6 +19,7 @@
> #include <linux/gpio/consumer.h>
> #include <asm/div64.h>
> #include <linux/clk.h>
> +#include <linux/clk-provider.h>
>
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
> @@ -31,11 +32,21 @@ enum {
> ADF4350_PWRDOWN,
> };
>
> +struct adf4350_output {
> + struct clk_hw hw;
> + struct iio_dev *indio_dev;
> +};
> +
> +#define to_output(_hw) container_of(_hw, struct adf4350_output, hw)
> +
> struct adf4350_state {
> struct spi_device *spi;
> struct gpio_desc *lock_detect_gpiod;
> struct adf4350_platform_data *pdata;
> struct clk *clk;
> + struct clk *clkout;
> + const char *clk_out_name;
> + struct adf4350_output output;
> unsigned long clkin;
> unsigned long chspc; /* Channel Spacing */
> unsigned long fpfd; /* Phase Frequency Detector */
> @@ -264,6 +275,10 @@ static ssize_t adf4350_write(struct iio_dev *indio_dev,
> mutex_lock(&st->lock);
> switch ((u32)private) {
> case ADF4350_FREQ:
> + if (st->clkout) {
> + ret = clk_set_rate(st->clkout, readin);
> + break;
> + }
> ret = adf4350_set_freq(st, readin);
> break;
> case ADF4350_FREQ_REFIN:
> @@ -381,6 +396,115 @@ static const struct iio_info adf4350_info = {
> .debugfs_reg_access = &adf4350_reg_access,
> };
>
> +static void adf4350_clk_del_provider(void *data)
> +{
> + struct adf4350_state *st = data;
> +
> + of_clk_del_provider(st->spi->dev.of_node);
> +}
> +
> +static unsigned long adf4350_clk_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct iio_dev *indio_dev = to_output(hw)->indio_dev;
> + struct adf4350_state *st = iio_priv(indio_dev);
> + unsigned long long tmp;
> +
> + tmp = (u64)(st->r0_int * st->r1_mod + st->r0_fract) * st->fpfd;
> + do_div(tmp, st->r1_mod * (1 << st->r4_rf_div_sel));
> +
> + return tmp;
> +}
> +
> +static int adf4350_clk_set_rate(struct clk_hw *hw,
> + unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct iio_dev *indio_dev = to_output(hw)->indio_dev;
> + struct adf4350_state *st = iio_priv(indio_dev);
> +
> + if (parent_rate == 0 || parent_rate > ADF4350_MAX_FREQ_REFIN)
> + return -EINVAL;
> +
> + st->clkin = parent_rate;
> +
> + return adf4350_set_freq(st, rate);
> +}
> +
> +static int adf4350_clk_prepare(struct clk_hw *hw)
> +{
> + struct iio_dev *indio_dev = to_output(hw)->indio_dev;
> + struct adf4350_state *st = iio_priv(indio_dev);
> +
> + st->regs[ADF4350_REG2] &= ~ADF4350_REG2_POWER_DOWN_EN;
> +
> + return adf4350_sync_config(st);
> +}
> +
> +static void adf4350_clk_unprepare(struct clk_hw *hw)
> +{
> + struct iio_dev *indio_dev = to_output(hw)->indio_dev;
> + struct adf4350_state *st = iio_priv(indio_dev);
> +
> + st->regs[ADF4350_REG2] |= ADF4350_REG2_POWER_DOWN_EN;
> +
> + adf4350_sync_config(st);
> +}
> +
> +static int adf4350_clk_is_enabled(struct clk_hw *hw)
> +{
> + struct iio_dev *indio_dev = to_output(hw)->indio_dev;
> + struct adf4350_state *st = iio_priv(indio_dev);
> +
> + return (st->regs[ADF4350_REG2] & ADF4350_REG2_POWER_DOWN_EN);
> +}
> +
> +static const struct clk_ops adf4350_clk_ops = {
> + .recalc_rate = adf4350_clk_recalc_rate,
> + .set_rate = adf4350_clk_set_rate,
> + .prepare = adf4350_clk_prepare,
> + .unprepare = adf4350_clk_unprepare,
> + .is_enabled = adf4350_clk_is_enabled,
> +};
> +
> +static int adf4350_clk_register(struct adf4350_state *st)
> +{
> + struct spi_device *spi = st->spi;
> + struct clk_init_data init;
> + struct clk *clk;
> + const char *parent_name;
> + int ret;
> +
> + if (!device_property_present(&spi->dev, "#clock-cells"))
> + return 0;
> +
> + init.name = devm_kasprintf(&spi->dev, GFP_KERNEL, "%s-clk",
> + fwnode_get_name(dev_fwnode(&spi->dev)));
> + device_property_read_string(&spi->dev, "clock-output-names",
> + &init.name);
> +
> + parent_name = of_clk_get_parent_name(spi->dev.of_node, 0);
> + if (!parent_name)
> + return -EINVAL;
> +
> + init.ops = &adf4350_clk_ops;
> + init.parent_names = &parent_name;
> + init.num_parents = 1;
> +
> + st->output.hw.init = &init;
> + clk = devm_clk_register(&spi->dev, &st->output.hw);
> + if (IS_ERR(clk))
> + return PTR_ERR(clk);
> +
> + ret = of_clk_add_provider(spi->dev.of_node, of_clk_src_simple_get,
> clk);
> + if (ret)
> + return ret;
> +
I totally agree this chip should be a clock provider (maybe it should even in
drivers/clk from the beginning) but there's one thing that comes to my mind.
Should we still expose the IIO userspace interface in case we register it as a
clock provider?
Sure, we do have clk notifiers in the kernel but I still think it's a sensible
question :)
I suspect we have another "outliers" in drivers/iio/frequency :)
- Nuno Sá
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