iio: adc: imx8qxp: Convert to platform remove callback returning void

The .remove() callback for a platform driver returns an int which makes
many driver authors wrongly assume it's possible to do error handling by
returning an error code. However the value returned is ignored (apart
from emitting a warning) and this typically results in resource leaks.
To improve here there is a quest to make the remove callback return
void. In the first step of this quest all drivers are converted to
.remove_new() which already returns void. Eventually after all drivers
are converted, .remove_new() will be renamed to .remove().

Trivially convert this driver from always returning zero in the remove
callback to the void returning variant.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230919174931.1417681-13-u.kleine-koenig@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: imx8qxp: Fix address for command buffer registers

The ADC Command Buffer Register high and low are currently pointing to
the wrong address and makes it impossible to perform correct
ADC measurements over all channels.

According to the datasheet of the imx8qxp the ADC_CMDL register starts
at address 0x100 and the ADC_CMDH register starts at address 0x104.

This bug seems to be in the kernel since the introduction of this
driver.

This can be observed by checking all raw voltages of the adc and they
are all nearly identical:

cat /sys/bus/iio/devices/iio\:device0/in_voltage*_raw
3498
3494
3491
3491
3489
3490
3490
3490

Fixes: 1e23dcaa1a9fa ("iio: imx8qxp-adc: Add driver support for NXP IMX8QXP ADC")
Signed-off-by: Philipp Rossak <embed3d@gmail.com>
Acked-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://lore.kernel.org/r/20230904220204.23841-1-embed3d@gmail.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: imx8qxp-adc: fix irq flood when call imx8qxp_adc_read_raw()

irq flood happen when run
cat /sys/bus/iio/devices/iio:device0/in_voltage1_raw

imx8qxp_adc_read_raw()
{
...
enable irq
/* adc start */
writel(1, adc->regs + IMX8QXP_ADR_ADC_SWTRIG);
^^^^ trigger irq flood.
wait_for_completion_interruptible_timeout();
readl(adc->regs + IMX8QXP_ADR_ADC_RESFIFO);
^^^^ clear irq here.
...
}

There is only FIFO watermark interrupt at this ADC controller.
IRQ line will be assert until software read data from FIFO.
So IRQ flood happen during wait_for_completion_interruptible_timeout().

Move FIFO read into irq handle to avoid irq flood.

Fixes: 1e23dcaa1a9f ("iio: imx8qxp-adc: Add driver support for NXP IMX8QXP ADC")
Cc: stable@vger.kernel.org

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Cai Huoqing <cai.huoqing@linux.dev>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Link: https://lore.kernel.org/r/20221201140110.2653501-1-Frank.Li@nxp.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: imx8qxp-adc: propagate regulator_get_voltage error

If the ADC vref regulator returns an error, for example, if CONFIG_REGULATOR
is not set, the error will be used as a reference voltage.

Introduce a guard for negative return values instead of unconditionally
casting it to u32.

Acked-by: Haibo Chen <haibo.chen@nxp.com>
Signed-off-by: Martin Larsson <martin.larsson@actia.se>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20220720153136.3502440-1-martin.larsson@actia.se
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: adc: imx8qxp: Switch to DEFINE_RUNTIME_DEV_PM_OPS and pm_ptr()

Switching to these newer macros allows the compiler to remove
the unused functions and struct dev_pm_ops if !CONFIG_PM without
the need to mark anything __maybe_unused.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Cai Huoqing <cai.huoqing@linux.dev>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/20220621202719.13644-28-jic23@kernel.org

iio: adc: imx8qxp-adc: explicitly add proper header files

Do not trust the fact that iio.h includes of.h which in turn includes
all the headers we are relying on.

The ultimate goal is to actually drop of.h from iio.h.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220610084545.547700-6-nuno.sa@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: imx8qxp-adc: mark PM functions as __maybe_unused

Without CONFIG_PM_SLEEP, the runtime suspend/resume functions
are unused, producing a warning:

drivers/iio/adc/imx8qxp-adc.c:433:12: error: 'imx8qxp_adc_runtime_resume' defined but not used [-Werror=unused-function]
433 | static int imx8qxp_adc_runtime_resume(struct device *dev)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/iio/adc/imx8qxp-adc.c:419:12: error: 'imx8qxp_adc_runtime_suspend' defined but not used [-Werror=unused-function]
419 | static int imx8qxp_adc_runtime_suspend(struct device *dev)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~

Mark them as __maybe_unused to shut up the compiler.

Fixes: 1e23dcaa1a9f ("iio: imx8qxp-adc: Add driver support for NXP IMX8QXP ADC")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Cai Huoqing <caihuoqing@baidu.com>
Link: https://lore.kernel.org/r/20211013144338.2261316-1-arnd@kernel.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: imx8qxp-adc: Add driver support for NXP IMX8QXP ADC

The NXP i.MX 8QuadXPlus SOC has a new ADC IP, so add
driver support for this ADC.

Signed-off-by: Cai Huoqing <caihuoqing@baidu.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20210925020555.129-2-caihuoqing@baidu.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>