pinctrl: zynq: configure SPI SSx pins separately

Since SCLK, MISO and MOSI are the only mandatory signals at Zynq's SPI interfaces, SS0, SS1 and SS2 have to be configured separately as they may be used as simple GPIO lines.

This, of course, has to be considered in the devicetree, so pin controller configuration for e.g. an SPI0 using SS0 and SS1 only might look like the following snippet (derived from the example of chapter "17.5.3 MIO/EMIO" Routing of Zynq-7000 TRM UG585). So MIO20 can now be used as GPIO instead of being occupied by SPI0 SS2 function. Note the separate pinmux function for the slave select signals:

pinctrl_spi0_default: spi0-default {
	mux_spi {
		function = "spi0";
		groups = "spi0_0_grp";
	};

	mux_ss {
		function = "spi0_ss";
		groups = "spi0_0_ss0_grp", "spi0_0_ss1_grp";
	}

	conf-output {
		pins = "MIO16", "MIO21";
		slew-rate = <0>;
		bias-disable;
		low-power-disable;
		io-standard = <1>;
	};

	conf-input {
		pins = "MIO17";
		slew-rate = <0>;
		bias-high-impedance;
		low-power-disable;
		io-standard = <1>;
	};

	conf-select {
		pins = "MIO18", "MIO19";
		slew-rate = <0>;
		bias-pull-up;
		low-power-disable;
		io-standard = <1>;
	};
};

pinctrl_gpio0_default {
	mux {
		function = "gpio0";
		groups = "gpio0_20_grp"
	};

	conf {
		pins = "MIO20";
		slew-rate = <0>;
		bias-pull-up;
		low-power-disable;
		io-standard = <1>;
	};
};

---
 .../bindings/pinctrl/xlnx,zynq-pinctrl.txt         |    7 +-
 drivers/pinctrl/pinctrl-zynq.c                     |   70 ++++++++++++++++++--
 2 files changed, 67 insertions(+), 10 deletions(-)

index b7b55a9..f488b0f 100644
@@ -45,8 +45,9 @@ to specify in a pinconf subnode:
 
  Valid values for groups are:
    ethernet0_0_grp, ethernet1_0_grp, mdio0_0_grp, mdio1_0_grp,
-   qspi0_0_grp, qspi1_0_grp, qspi_fbclk, qspi_cs1_grp, spi0_0_grp,
-   spi0_1_grp - spi0_2_grp, spi1_0_grp - spi1_3_grp, sdio0_0_grp - sdio0_2_grp,
+   qspi0_0_grp, qspi1_0_grp, qspi_fbclk, qspi_cs1_grp, spi0_0_grp - spi0_2_grp,
+   spi0_X_ssY (X=0..2, Y=0..2), spi1_0_grp - spi1_3_grp,
+   spi1_X_ssY (X=0..3, Y=0..2), sdio0_0_grp - sdio0_2_grp,
    sdio1_0_grp - sdio1_3_grp, sdio0_emio_wp, sdio0_emio_cd, sdio1_emio_wp,
    sdio1_emio_cd, smc0_nor, smc0_nor_cs1_grp, smc0_nor_addr25_grp, smc0_nand,
    can0_0_grp - can0_10_grp, can1_0_grp - can1_11_grp, uart0_0_grp - uart0_10_grp,

@@ -59,7 +60,7 @@ to specify in a pinconf subnode:
 
  Valid values for function are:
    ethernet0, ethernet1, mdio0, mdio1, qspi0, qspi1, qspi_fbclk, qspi_cs1,
-   spi0, spi1, sdio0, sdio0_pc, sdio0_cd, sdio0_wp,
+   spi0, spi0_ss, spi1, spi1_ss, sdio0, sdio0_pc, sdio0_cd, sdio0_wp,
    sdio1, sdio1_pc, sdio1_cd, sdio1_wp,
    smc0_nor, smc0_nor_cs1, smc0_nor_addr25, smc0_nand, can0, can1, uart0, uart1,
    i2c0, i2c1, ttc0, ttc1, swdt0, gpio0, usb0, usb1

1.7.10.4

For future reference, please keep a changelog here when sending another iteration of a patch.

Regards,
Sören

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This v2 patch applied with Sören's ACK.

Yours,
Linus Walleij
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