Re: [PATCH] spi: imx/fsl-lpspi: Convert to GPIO descriptors

[Shawn Guo <shawnguo@kernel.org>]

On Thu, Jun 25, 2020 at 10:02:52PM +0200, Linus Walleij wrote:
> This converts the two Freescale i.MX SPI drivers
> Freescale i.MX (CONFIG_SPI_IMX) and Freescale i.MX LPSPI
> (CONFIG_SPI_FSL_LPSPI) to use GPIO descriptors handled in
> the SPI core for GPIO chip selects whether defined in
> the device tree or a board file.
> 
> The reason why both are converted at the same time is
> that they were both using the same platform data and
> platform device population helpers when using
> board files intertwining the code so this gives a cleaner
> cut.
> 
> The platform device creation was passing a platform data
> container from each boardfile down to the driver using
> struct spi_imx_master from <linux/platform_data/spi-imx.h>,
> but this was only conveying the number of chipselects and
> an int * array of the chipselect GPIO numbers.
> 
> The imx27 and imx31 platforms had code passing the
> now-unused platform data when creating the platform devices,
> this has been repurposed to pass around GPIO descriptor
> tables. The platform data struct that was just passing an
> array of integers and number of chip selects for the GPIO
> lines has been removed.
> 
> The number of chipselects used to be passed from the board
> file, because this number also limits the number of native
> chipselects that the platform can use. To deal with this we
> just augment the i.MX (CONFIG_SPI_IMX) driver to support 3
> chipselects if the platform does not define "num-cs" as a
> device property (such as from the device tree). This covers
> all the legacy boards as these use <= 3 native chip selects
> (or GPIO lines, and in that case the number of chip selects
> is determined by the core from the number of available
> GPIO lines). Any new boards should use device tree, so
> this is a reasonable simplification to cover all old
> boards.
> 
> The LPSPI driver never assigned the number of chipselects
> and thus always fall back to the core default of 1 chip
> select if no GPIOs are defined in the device tree.
> 
> The Freescale i.MX driver was already partly utilizing
> the SPI core to obtain the GPIO numbers from the device tree,
> so this completes the transtion to let the core handle all
> of it.
> 
> All board files and the core i.MX boardfile registration
> code is augmented to account for these changes.
> 
> This has been compile-tested with the imx_v4_v5_defconfig
> and the imx_v6_v7_defconfig.
> 
> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Cc: Robin Gong <yibin.gong@nxp.com>
> Cc: Trent Piepho <tpiepho@impinj.com>
> Cc: Clark Wang <xiaoning.wang@nxp.com>
> Cc: Shawn Guo <shawnguo@kernel.org>

Acked-by: Shawn Guo <shawnguo@kernel.org>