pinctrl: add ZTE ZX pinctrl driver support

The pin controller on ZTE ZX platforms is kinda of hybrid.  It consists
of a main controller and an auxiliary one.  For example, on ZX296718 SoC,
the main controller is TOP_PMM and the auxiliary one is AON_IOCFG.  Both
controllers work together to control pin multiplexing and configuration.

For most of pins, the pinmux function is controlled by main controller
only, and this type of pins are meant by term 'TOP pins'.  For other
pins, the pinmux is controlled by both main and auxiliary controllers,
as the available multiplexing functions for the pin spread in both
controllers.  This type of pins are called 'AON pins'.  Though pinmux
implementation is quite different, pinconf is same for both types of
pins.  Both are controlled by auxiliary controller, i.e. AON_IOCFG on
ZX296718.

The patch adds the ZTE ZX core pinctrl driver to support this hybrid
pin controller as well as ZX296718 SoC specific pin data.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/Kconfig

@@ -315,6 +315,7 @@ source "drivers/pinctrl/ti/Kconfig"
 source "drivers/pinctrl/uniphier/Kconfig"
 source "drivers/pinctrl/vt8500/Kconfig"
 source "drivers/pinctrl/mediatek/Kconfig"
+source "drivers/pinctrl/zte/Kconfig"
 
 config PINCTRL_XWAY
 	bool

drivers/pinctrl/Makefile

@@ -58,3 +58,4 @@ obj-y				+= ti/
 obj-$(CONFIG_PINCTRL_UNIPHIER)	+= uniphier/
 obj-$(CONFIG_ARCH_VT8500)	+= vt8500/
 obj-$(CONFIG_PINCTRL_MTK)	+= mediatek/
+obj-$(CONFIG_PINCTRL_ZX)	+= zte/

drivers/pinctrl/zte/Kconfig

+config PINCTRL_ZX
+	bool
+	select PINMUX
+	select GENERIC_PINCONF
+	select GENERIC_PINCTRL_GROUPS
+	select GENERIC_PINMUX_FUNCTIONS
+
+config PINCTRL_ZX296718
+	bool "ZTE ZX296718 pinctrl driver"
+	depends on OF && ARCH_ZX
+	select PINCTRL_ZX
+	help
+	  Say Y here to enable the ZX296718 pinctrl driver

drivers/pinctrl/zte/Makefile

+obj-$(CONFIG_PINCTRL_ZX)	+= pinctrl-zx.o
+obj-$(CONFIG_PINCTRL_ZX296718)	+= pinctrl-zx296718.o

drivers/pinctrl/zte/pinctrl-zx.h

+/*
+ * Copyright (C) 2017 Sanechips Technology Co., Ltd.
+ * Copyright 2017 Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __PINCTRL_ZX_H
+#define __PINCTRL_ZX_H
+
+/**
+ * struct zx_mux_desc - hardware mux descriptor
+ * @name: mux function name
+ * @muxval: mux register bit value
+ */
+struct zx_mux_desc {
+	const char *name;
+	u8 muxval;
+};
+
+/**
+ * struct zx_pin_data - hardware per-pin data
+ * @aon_pin: whether it's an AON pin
+ * @offset: register offset within TOP pinmux controller
+ * @bitpos: bit position within TOP pinmux register
+ * @width: bit width within TOP pinmux register
+ * @coffset: pinconf register offset within AON controller
+ * @cbitpos: pinconf bit position within AON register
+ * @muxes: available mux function names and corresponding register values
+ *
+ * Unlike TOP pinmux and AON pinconf registers which are arranged pretty
+ * arbitrarily, AON pinmux register bits are well organized per pin id, and
+ * each pin occupies two bits, so that we can calculate the AON register offset
+ * and bit position from pin id.  Thus, we only need to define TOP pinmux and
+ * AON pinconf register data for the pin.
+ */
+struct zx_pin_data {
+	bool aon_pin;
+	u16 offset;
+	u16 bitpos;
+	u16 width;
+	u16 coffset;
+	u16 cbitpos;
+	struct zx_mux_desc *muxes;
+};
+
+struct zx_pinctrl_soc_info {
+	const struct pinctrl_pin_desc *pins;
+	unsigned int npins;
+};
+
+#define TOP_PIN(pin, off, bp, wd, coff, cbp, ...) {		\
+	.number = pin,						\
+	.name = #pin,						\
+	.drv_data = &(struct zx_pin_data) {			\
+		.aon_pin = false,				\
+		.offset = off,					\
+		.bitpos = bp,					\
+		.width = wd,					\
+		.coffset = coff,				\
+		.cbitpos = cbp,					\
+		.muxes = (struct zx_mux_desc[]) {		\
+			 __VA_ARGS__, { } },			\
+	},							\
+}
+
+#define AON_PIN(pin, off, bp, wd, coff, cbp, ...) {		\
+	.number = pin,						\
+	.name = #pin,						\
+	.drv_data = &(struct zx_pin_data) {			\
+		.aon_pin = true,				\
+		.offset = off,					\
+		.bitpos = bp,					\
+		.width = wd,					\
+		.coffset = coff,				\
+		.cbitpos = cbp,					\
+		.muxes = (struct zx_mux_desc[]) {		\
+			 __VA_ARGS__, { } },			\
+	},							\
+}
+
+#define ZX_RESERVED(pin) PINCTRL_PIN(pin, #pin)
+
+#define TOP_MUX(_val, _name) {					\
+	.name = _name,						\
+	.muxval = _val,						\
+}
+
+/*
+ * When the flag is set, it's a mux configuration for an AON pin that sits in
+ * AON register.  Otherwise, it's one for AON pin but sitting in TOP register.
+ */
+#define AON_MUX_FLAG BIT(7)
+
+#define AON_MUX(_val, _name) {					\
+	.name = _name,						\
+	.muxval = _val | AON_MUX_FLAG,				\
+}
+
+int zx_pinctrl_init(struct platform_device *pdev,
+		    struct zx_pinctrl_soc_info *info);
+
+#endif /* __PINCTRL_ZX_H */