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SubjectRe: [PATCH 05/16] iio: adc: sun4i-gpadc-iio: rework: support clocks and reset
On Fri, 26 Jan 2018 16:19:30 +0100
Philipp Rossak <embed3d@gmail.com> wrote:

> For adding newer sensor some basic rework of the code is necessary.
>
> The SoCs after H3 has newer thermal sensor ADCs, which have two clock
> inputs (bus clock and sampling clock) and a reset. The registers are
> also re-arranged.
>
> This commit reworks the code, adds the process of the clocks and
> resets.
>
> Signed-off-by: Philipp Rossak <embed3d@gmail.com>
> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>

Both clock and reset code is safe against null parameters, so you can
drop a lot of 'is it here' checks in this. They could be argued to
act as documentation of the fact we really don't expect them in some cases
I suppose...

> ---
> drivers/iio/adc/sun4i-gpadc-iio.c | 80 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 80 insertions(+)
>
> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
> index 363936b37c5a..1a80744bd472 100644
> --- a/drivers/iio/adc/sun4i-gpadc-iio.c
> +++ b/drivers/iio/adc/sun4i-gpadc-iio.c
> @@ -22,6 +22,7 @@
> * shutdown for not being used.
> */
>
> +#include <linux/clk.h>
> #include <linux/completion.h>
> #include <linux/interrupt.h>
> #include <linux/io.h>
> @@ -31,6 +32,7 @@
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> #include <linux/regmap.h>
> +#include <linux/reset.h>
> #include <linux/thermal.h>
> #include <linux/delay.h>
>
> @@ -75,6 +77,9 @@ struct gpadc_data {
> u32 ctrl2_map;
> u32 sensor_en_map;
> u32 filter_map;
> + bool has_bus_clk;
> + bool has_bus_rst;
> + bool has_mod_clk;
> };
>
> static const struct gpadc_data sun4i_gpadc_data = {
> @@ -134,6 +139,9 @@ struct sun4i_gpadc_iio {
> atomic_t ignore_temp_data_irq;
> const struct gpadc_data *data;
> bool no_irq;
> + struct clk *bus_clk;
> + struct clk *mod_clk;
> + struct reset_control *reset;
> /* prevents concurrent reads of temperature and ADC */
> struct mutex mutex;
> struct thermal_zone_device *tzd;
> @@ -435,6 +443,12 @@ static int sun4i_gpadc_runtime_suspend(struct device *dev)
> {
> struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
>
> + if (info->data->has_mod_clk)
> + clk_disable(info->mod_clk);

Safe against null parameter... (see below)

> +
> + if (info->data->has_bus_clk)
> + clk_disable(info->bus_clk);
> +
> return info->data->sample_end(info);
> }
>
> @@ -483,6 +497,12 @@ static int sun4i_gpadc_runtime_resume(struct device *dev)
> {
> struct sun4i_gpadc_iio *info = iio_priv(dev_get_drvdata(dev));
>
> + if (info->data->has_mod_clk)
> + clk_enable(info->mod_clk);

clk_enable is safe against null parameter so could do without the checks.

> +
> + if (info->data->has_bus_clk)
> + clk_enable(info->bus_clk);
> +
> return info->data->sample_start(info);
> }
>
> @@ -597,10 +617,61 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
> return ret;
> }
>
> + if (info->data->has_bus_rst) {
> + info->reset = devm_reset_control_get(&pdev->dev, NULL);
> + if (IS_ERR(info->reset)) {
> + ret = PTR_ERR(info->reset);
> + return ret;
> + }
> +
> + ret = reset_control_deassert(info->reset);
> + if (ret)
> + return ret;
> + }
> +
> + if (info->data->has_bus_clk) {
> + info->bus_clk = devm_clk_get(&pdev->dev, "bus");
> + if (IS_ERR(info->bus_clk)) {
> + ret = PTR_ERR(info->bus_clk);
> + goto assert_reset;
> + }
> +
> + ret = clk_prepare_enable(info->bus_clk);
> + if (ret)
> + goto assert_reset;
> + }
> +
> + if (info->data->has_mod_clk) {
> + info->mod_clk = devm_clk_get(&pdev->dev, "mod");
> + if (IS_ERR(info->mod_clk)) {
> + ret = PTR_ERR(info->mod_clk);
> + goto disable_bus_clk;
> + }
> +
> + /* Running at 6MHz */
> + ret = clk_set_rate(info->mod_clk, 4000000);
> + if (ret)
> + goto disable_bus_clk;
> +
> + ret = clk_prepare_enable(info->mod_clk);
> + if (ret)
> + goto disable_bus_clk;
> + }
> +
> if (IS_ENABLED(CONFIG_THERMAL_OF))
> info->sensor_device = &pdev->dev;
>
> return 0;
> +
> +disable_bus_clk:
> + if (info->data->has_bus_clk)
> + clk_disable_unprepare(info->bus_clk);
> +
> +assert_reset:
> + if (info->data->has_bus_rst)
> + reset_control_assert(info->reset);
> +
> + return ret;
> }
>
> static int sun4i_gpadc_probe_mfd(struct platform_device *pdev,
> @@ -766,6 +837,15 @@ static int sun4i_gpadc_remove(struct platform_device *pdev)
> if (!info->no_irq)
> iio_map_array_unregister(indio_dev);
>
> + if (info->data->has_mod_clk)
> + clk_disable_unprepare(info->mod_clk);

clk_disable_unprepare is safe against a null parameter
so I don't think the checks are needed.

> +
> + if (info->data->has_bus_clk)
> + clk_disable_unprepare(info->bus_clk);
> +
> + if (info->data->has_bus_rst)
> + reset_control_assert(info->reset);

Safe against null parameter...

> +
> return 0;
> }
>

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