mmc: starfive: Change tuning implementation

Before, we used syscon to achieve tuning, but the actual measurement
showed little effect, so the tuning implementation was modified here,
and it was realized by reading and writing the UHS_REG_EXT register.

Signed-off-by: William Qiu <william.qiu@starfivetech.com>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Link: https://lore.kernel.org/r/20230922062834.39212-3-william.qiu@starfivetech.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: dw_mmc: Make dw_mci_pltfm_remove() return void

dw_mci_pltfm_remove() returned zero unconditionally. Make it return void
instead which makes its semantics a bit clearer.

Convert the drivers that use this function as .remove() callback to
.remove_new() which has the right prototype. This helps getting rid of
the platform_driver's remove callback that returns an int (which is
error prone). The other users didn't check the return value anyhow.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230505221506.1247424-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: dw_mmc-starfive: Fix initialization of prev_err

Fix a bug by making sure prev_err doesn't get used when being
uninitialized.

Signed-off-by: William Qiu <william.qiu@starfivetech.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Fixes: 9e622229bbf4 ("mmc: starfive: Add sdio/emmc driver support")
Link: https://lore.kernel.org/r/20230307024646.10216-3-william.qiu@starfivetech.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

mmc: starfive: Add sdio/emmc driver support

Add sdio/emmc driver support for StarFive JH7110 soc.

Tested-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: William Qiu <william.qiu@starfivetech.com>
Link: https://lore.kernel.org/r/20230215113249.47727-3-william.qiu@starfivetech.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>