Requesting quad mode for the FMC resulted in an error:
&fmc {
status = "okay";
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_fwqspi_default>'
[ 0.742963] aspeed-g6-pinctrl
1e6e2000.syscon:pinctrl: invalid function FWQSPID in map table

This is because the quad mode pins are a group of pins, not a function.
After applying this patch we can request the pins and the QSPI data
lines are muxed:
# cat /sys/kernel/debug/pinctrl/
1e6e2000.syscon\:pinctrl-aspeed-g6-pinctrl/pinmux-pins |grep
1e620000.spi
pin 196 (AE12): device
1e620000.spi function FWSPID group FWQSPID
pin 197 (AF12): device
1e620000.spi function FWSPID group FWQSPID
pin 240 (Y1): device
1e620000.spi function FWSPID group FWQSPID
pin 241 (Y2): device
1e620000.spi function FWSPID group FWQSPID
pin 242 (Y3): device
1e620000.spi function FWSPID group FWQSPID
pin 243 (Y4): device
1e620000.spi function FWSPID group FWQSPID
Fixes: ffbea824d26a ("ARM: dts: aspeed: Add AST2600 pinmux nodes")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20220304011010.974863-1-joel@jms.id.au
Link: https://lore.kernel.org/r/20220304011010.974863-1-joel@jms.id.au'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
};
pinctrl_fwqspid_default: fwqspid_default {
- function = "FWQSPID";
+ function = "FWSPID";
groups = "FWQSPID";
};