mfd: stm32-timers: 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/20231123165627.492259-16-u.kleine-koenig@pengutronix.de
Signed-off-by: Lee Jones <lee@kernel.org>

mfd: stm32-timers: Add support for interrupts

There are two types of STM32 timers that may have:

- a global interrupt line
- 4 dedicated interrupt lines.

Those interrupts are optional as defined in the dt-bindings. Enforce checks
on either one, four or no interrupts are provided with their names.
Optionally get them here, to be used by child devices.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20230829134029.2402868-5-fabrice.gasnier@foss.st.com
Signed-off-by: Lee Jones <lee@kernel.org>

mfd: Explicitly include correct DT includes

The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.

Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230714174731.4059811-1-robh@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

mfd: stm32-timers: Use devm_platform_get_and_ioremap_resource()

Convert platform_get_resource(), devm_ioremap_resource() to a single
call to devm_platform_get_and_ioremap_resource(), as this is exactly
what this function does.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Link: https://lore.kernel.org/r/20230706113939.1178-6-frank.li@vivo.com
Signed-off-by: Lee Jones <lee@kernel.org>

mfd: stm32-timers: Avoid clearing auto reload register

The ARR register is cleared unconditionally upon probing, after the maximum
value has been read. This initial condition is rather not intuitive, when
considering the counter child driver. It rather expects the maximum value
by default:
- The counter interface shows a zero value by default for 'ceiling'
attribute.
- Enabling the counter without any prior configuration makes it doesn't
count.

The reset value of ARR register is the maximum. So Choice here
is to backup it, and restore it then, instead of clearing its value.
It also fixes the initial condition seen by the counter driver.

Fixes: d0f949e220fd ("mfd: Add STM32 Timers driver")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd: stm32-timers: Use dma_request_chan() instead dma_request_slave_channel()

dma_request_slave_channel() is a wrapper on top of dma_request_chan()
eating up the error code.

By using dma_request_chan() directly the driver can support deferred
probing against DMA.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd: stm32-timers: Add support for DMAs

STM32 Timers can support up to 7 DMA requests:
- 4 channels, update, compare and trigger.
Optionally request part, or all DMAs from stm32-timers MFD core.

Also add routine to implement burst reads using DMA from timer registers.
This is exported. So, it can be used by child drivers, PWM capture
for instance (but not limited to).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd: stm32: Adopt SPDX identifier

Add SPDX identifier

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd: stm32-timers: Use devm_of_platform_populate()

Use devm_of_platform_populate() instead of of_platform_populate()
and suppress stm32_timers_remove() which become useless.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd: stm32-timers: Fix max register

STM32 timers register bank size is 0x400. Fix regmap max_register.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd: stm32-timers: Fix driver removal

Add missing of_platform_depopulate() upon driver removal.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

mfd: Add STM32 Timers driver

This hardware block could at used at same time for PWM generation
and IIO timers.
PWM and IIO timer configuration are mixed in the same registers
so we need a multi fonction driver to be able to share those registers.

version 7:
- rebase on v4.10-rc2

version 6:
- rename files to stm32-timers
- rename functions to stm32_timers_xxx

version 5:
- fix Lee comments about detect function
- add missing dependency on REGMAP_MMIO

version 4:
- add a function to detect Auto Reload Register (ARR) size
- rename the structure shared with other drivers

version 2:
- rename driver "stm32-gptimer" to be align with SoC documentation
- only keep one compatible
- use of_platform_populate() instead of devm_mfd_add_devices()

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>