Re: [PATCH v3 17/30] iio: adc: sun4i-gpadc-iio: rework: support clocks and reset

Maxime Ripard
2018-08-31T13:09:39Z

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On Thu, Aug 30, 2018 at 05:45:05PM +0200, Philipp Rossak 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>
> ---
> drivers/iio/adc/sun4i-gpadc-iio.c | 72 +++++++++++++++++++++++++++++++++++++--
> 1 file changed, 70 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/sun4i-gpadc-iio.c b/drivers/iio/adc/sun4i-gpadc-iio.c
> index c278e165e161..c12de48c4e86 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>
>
> @@ -63,6 +65,9 @@ struct gpadc_data {
> int (*ths_suspend)(struct sun4i_gpadc_iio *info);
> int (*ths_resume)(struct sun4i_gpadc_iio *info);
> bool support_irq;
> + bool has_bus_clk;
> + bool has_bus_rst;
> + bool has_mod_clk;
> u32 temp_data_base;
> };
>
> @@ -127,6 +132,9 @@ struct sun4i_gpadc_iio {
> struct mutex mutex;
> struct thermal_zone_device *tzd;
> struct device *sensor_device;
> + struct clk *bus_clk;
> + struct clk *mod_clk;
> + struct reset_control *reset;
> };
>
> static const struct iio_chan_spec sun4i_gpadc_channels[] = {
> @@ -472,8 +480,13 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
> if (IS_ERR(base))
> return PTR_ERR(base);
>
> - info->regmap = devm_regmap_init_mmio(&pdev->dev, base,
> - &sun4i_gpadc_regmap_config);
> + if (info->data->has_bus_clk)
> + info->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "bus",
> + base, &sun4i_gpadc_regmap_config);
> + else
> + info->regmap = devm_regmap_init_mmio(&pdev->dev, base,
> + &sun4i_gpadc_regmap_config);
> +
> if (IS_ERR(info->regmap)) {
> ret = PTR_ERR(info->regmap);
> dev_err(&pdev->dev, "failed to init regmap: %d\n", ret);
> @@ -498,9 +511,58 @@ static int sun4i_gpadc_probe_dt(struct platform_device *pdev,
> }
> }
>
> + 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;

That should be done in the runtime_resume hook

> + }
> +
> + 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 4MHz */
> + ret = clk_set_rate(info->mod_clk, 4000000);
> + if (ret)
> + goto disable_bus_clk;

Why?

> + ret = clk_prepare_enable(info->mod_clk);
> + if (ret)
> + goto disable_bus_clk;
> + }
> +
> info->sensor_device = &pdev->dev;
>
> return 0;
> +
> +disable_bus_clk:
> + clk_disable_unprepare(info->bus_clk);
> +
> +assert_reset:
> + reset_control_assert(info->reset);

You should check for the variables here before calling those
functions, if you end up here with your variable not set, you'll have
improper refcounting.

Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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