pinctrl: introduce generic pin config

This is a split-off from the earlier patch set which adds generic
pin configuration for the pin controllers that want it. Since
we may have a system with mixed generic and custom pin controllers,
we pass a boolean in the pin controller ops vtable to indicate
if it is generic.

ChangeLog v1->v5:
- Follow parent patch versioning number system.
- Document the semantic meaning of return values from pin config
get functions, so we can iterate over pins and check their
properties from debugfs as part of the generic config code.
- Use proper cast functions in the generic debugfs pin config
file.
- Expand generic config to optionally cover groups too.
ChangeLog v5->v6:
- Update to match underlying changes.
ChangeLog v6->v7:
- Drop DRIVE_OFF parameter, use bias high impedance for this
- Delete argument for drive modes push-pull, od and os. These
are now just state transitions.
- Delete slew rate rising/falling due to discussions on on
proper semantics
- Drop config wakeup, struct irq_chip does this for now, add
back if need be.
- Set PIN_CONFIG_END to 0x7fff making room for custom config
parameters from 0x8000 and up.
- Prefix accessor functions with pinconf_

drivers/pinctrl/Kconfig

···
 config PINCONF
 	bool "Support pin configuration controllers"
 
+config GENERIC_PINCONF
+	bool
+	select PINCONF
+
 config DEBUG_PINCTRL
 	bool "Debug PINCTRL calls"
 	depends on DEBUG_KERNEL

drivers/pinctrl/Makefile

···
 obj-$(CONFIG_PINCTRL)		+= core.o
 obj-$(CONFIG_PINMUX)		+= pinmux.o
 obj-$(CONFIG_PINCONF)		+= pinconf.o
+obj-$(CONFIG_GENERIC_PINCONF)	+= pinconf-generic.o
 obj-$(CONFIG_PINCTRL_PXA3xx)	+= pinctrl-pxa3xx.o
 obj-$(CONFIG_PINCTRL_MMP2)	+= pinctrl-mmp2.o
 obj-$(CONFIG_PINCTRL_PXA168)	+= pinctrl-pxa168.o

drivers/pinctrl/pinconf-generic.c

···
+/*
+ * Core driver for the generic pin config portions of the pin control subsystem
+ *
+ * Copyright (C) 2011 ST-Ericsson SA
+ * Written on behalf of Linaro for ST-Ericsson
+ *
+ * Author: Linus Walleij <[e-mail]>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#define pr_fmt(fmt) "generic pinconfig core: " fmt
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/pinctrl/pinctrl.h>
+#include <linux/pinctrl/pinconf.h>
+#include <linux/pinctrl/pinconf-generic.h>
+#include "core.h"
+#include "pinconf.h"
+
+#ifdef CONFIG_DEBUG_FS
+
+struct pin_config_item {
+	const enum pin_config_param param;
+	const char * const display;
+	const char * const format;
+};
+
+#define PCONFDUMP(a, b, c) { .param = a, .display = b, .format = c }
+
+struct pin_config_item conf_items[] = {
+	PCONFDUMP(PIN_CONFIG_BIAS_DISABLE, "input bias disabled", NULL),
+	PCONFDUMP(PIN_CONFIG_BIAS_HIGH_IMPEDANCE, "input bias high impedance", NULL),
+	PCONFDUMP(PIN_CONFIG_BIAS_PULL_UP, "input bias pull up", NULL),
+	PCONFDUMP(PIN_CONFIG_BIAS_PULL_DOWN, "input bias pull down", NULL),
+	PCONFDUMP(PIN_CONFIG_DRIVE_PUSH_PULL, "output drive push pull", NULL),
+	PCONFDUMP(PIN_CONFIG_DRIVE_OPEN_DRAIN, "output drive open drain", NULL),
+	PCONFDUMP(PIN_CONFIG_DRIVE_OPEN_SOURCE, "output drive open source", NULL),
+	PCONFDUMP(PIN_CONFIG_INPUT_SCHMITT, "input schmitt trigger", NULL),
+	PCONFDUMP(PIN_CONFIG_INPUT_DEBOUNCE, "input debounce", "time units"),
+	PCONFDUMP(PIN_CONFIG_POWER_SOURCE, "pin power source", "selector"),
+	PCONFDUMP(PIN_CONFIG_LOW_POWER_MODE, "pin low power", "mode"),
+};
+
+void pinconf_generic_dump_pin(struct pinctrl_dev *pctldev,
+			      struct seq_file *s, unsigned pin)
+{
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+	int i;
+
+	if (!ops->is_generic)
+		return;
+
+	for(i = 0; i < ARRAY_SIZE(conf_items); i++) {
+		unsigned long config;
+		int ret;
+
+		/* We want to check out this parameter */
+		config = pinconf_to_config_packed(conf_items[i].param, 0);
+		ret = pin_config_get_for_pin(pctldev, pin, &config);
+		/* These are legal errors */
+		if (ret == -EINVAL || ret == -ENOTSUPP)
+			continue;
+		if (ret) {
+			seq_printf(s, "ERROR READING CONFIG SETTING %d ", i);
+			continue;
+		}
+		/* Space between multiple configs */
+		seq_puts(s, " ");
+		seq_puts(s, conf_items[i].display);
+		/* Print unit if available */
+		if (conf_items[i].format &&
+		    pinconf_to_config_argument(config) != 0)
+			seq_printf(s, " (%u %s)",
+				   pinconf_to_config_argument(config),
+				   conf_items[i].format);
+	}
+}
+
+void pinconf_generic_dump_group(struct pinctrl_dev *pctldev,
+			      struct seq_file *s, const char *gname)
+{
+	const struct pinconf_ops *ops = pctldev->desc->confops;
+	int i;
+
+	if (!ops->is_generic)
+		return;
+
+	for(i = 0; i < ARRAY_SIZE(conf_items); i++) {
+		unsigned long config;
+		int ret;
+
+		/* We want to check out this parameter */
+		config = pinconf_to_config_packed(conf_items[i].param, 0);
+		ret = pin_config_group_get(dev_name(pctldev->dev), gname,
+					   &config);
+		/* These are legal errors */
+		if (ret == -EINVAL || ret == -ENOTSUPP)
+			continue;
+		if (ret) {
+			seq_printf(s, "ERROR READING CONFIG SETTING %d ", i);
+			continue;
+		}
+		/* Space between multiple configs */
+		seq_puts(s, " ");
+		seq_puts(s, conf_items[i].display);
+		/* Print unit if available */
+		if (conf_items[i].format && config != 0)
+			seq_printf(s, " (%u %s)",
+				   pinconf_to_config_argument(config),
+				   conf_items[i].format);
+	}
+}
+
+#endif

drivers/pinctrl/pinconf.c

···
 	return 0;
 }
 
-static int pin_config_get_for_pin(struct pinctrl_dev *pctldev, unsigned pin,
+int pin_config_get_for_pin(struct pinctrl_dev *pctldev, unsigned pin,
 			   unsigned long *config)
 {
 	const struct pinconf_ops *ops = pctldev->desc->confops;
···
 {
 	const struct pinconf_ops *ops = pctldev->desc->confops;
 
+	/* no-op when not using generic pin config */
+	pinconf_generic_dump_pin(pctldev, s, pin);
 	if (ops && ops->pin_config_dbg_show)
 		ops->pin_config_dbg_show(pctldev, s, pin);
 }
···
 {
 	const struct pinconf_ops *ops = pctldev->desc->confops;
 
+	/* no-op when not using generic pin config */
+	pinconf_generic_dump_group(pctldev, s, gname);
 	if (ops && ops->pin_config_group_dbg_show)
 		ops->pin_config_group_dbg_show(pctldev, s, selector);
 }

drivers/pinctrl/pinconf.h

···
 #ifdef CONFIG_PINCONF
 
 int pinconf_check_ops(struct pinctrl_dev *pctldev);
-
 int pinconf_validate_map(struct pinctrl_map const *map, int i);
-
 int pinconf_map_to_setting(struct pinctrl_map const *map,
 			  struct pinctrl_setting *setting);
 void pinconf_free_setting(struct pinctrl_setting const *setting);
 int pinconf_apply_setting(struct pinctrl_setting const *setting);
-
 void pinconf_show_map(struct seq_file *s, struct pinctrl_map const *map);
 void pinconf_show_setting(struct seq_file *s,
 			  struct pinctrl_setting const *setting);
 void pinconf_init_device_debugfs(struct dentry *devroot,
 				 struct pinctrl_dev *pctldev);
+
+/*
+ * You will only be interested in these if you're using PINCONF
+ * so don't supply any stubs for these.
+ */
+int pin_config_get_for_pin(struct pinctrl_dev *pctldev, unsigned pin,
+			   unsigned long *config);
+int pin_config_group_get(const char *dev_name, const char *pin_group,
+			 unsigned long *config);
 
 #else
 
···
 static inline void pinconf_init_device_debugfs(struct dentry *devroot,
 					       struct pinctrl_dev *pctldev)
 {
+}
+
+#endif
+
+/*
+ * The following functions are available if the driver uses the generic
+ * pin config.
+ */
+
+#ifdef CONFIG_GENERIC_PINCONF
+
+void pinconf_generic_dump_pin(struct pinctrl_dev *pctldev,
+			      struct seq_file *s, unsigned pin);
+
+void pinconf_generic_dump_group(struct pinctrl_dev *pctldev,
+			      struct seq_file *s, const char *gname);
+
+#else
+
+static inline void pinconf_generic_dump_pin(struct pinctrl_dev *pctldev,
+					    struct seq_file *s,
+					    unsigned pin)
+{
+	return;
+}
+
+static inline void pinconf_generic_dump_group(struct pinctrl_dev *pctldev,
+					      struct seq_file *s,
+					      const char *gname)
+{
+	return;
 }
 
 #endif

include/linux/pinctrl/pinconf-generic.h

···
+/*
+ * Interface the generic pinconfig portions of the pinctrl subsystem
+ *
+ * Copyright (C) 2011 ST-Ericsson SA
+ * Written on behalf of Linaro for ST-Ericsson
+ * This interface is used in the core to keep track of pins.
+ *
+ * Author: Linus Walleij <[e-mail]>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+#ifndef __LINUX_PINCTRL_PINCONF_GENERIC_H
+#define __LINUX_PINCTRL_PINCONF_GENERIC_H
+
+/*
+ * You shouldn't even be able to compile with these enums etc unless you're
+ * using generic pin config. That is why this is defined out.
+ */
+#ifdef CONFIG_GENERIC_PINCONF
+
+/**
+ * enum pin_config_param - possible pin configuration parameters
+ * @PIN_CONFIG_BIAS_DISABLE: disable any pin bias on the pin, a
+ *	transition from say pull-up to pull-down implies that you disable
+ *	pull-up in the process, this setting disables all biasing.
+ * @PIN_CONFIG_BIAS_HIGH_IMPEDANCE: the pin will be set to a high impedance
+ *	mode, also know as "third-state" (tristate) or "high-Z" or "floating".
+ *	On output pins this effectively disconnects the pin, which is useful
+ *	if for example some other pin is going to drive the signal connected
+ *	to it for a while. Pins used for input are usually always high
+ *	impedance.
+ * @PIN_CONFIG_BIAS_PULL_UP: the pin will be pulled up (usually with high
+ *	impedance to VDD). If the argument is != 0 pull-up is enabled,
+ *	if it is 0, pull-up is disabled.
+ * @PIN_CONFIG_BIAS_PULL_DOWN: the pin will be pulled down (usually with high
+ *	impedance to GROUND). If the argument is != 0 pull-down is enabled,
+ *	if it is 0, pull-down is disabled.
+ * @PIN_CONFIG_DRIVE_PUSH_PULL: the pin will be driven actively high and
+ *	low, this is the most typical case and is typically achieved with two
+ *	active transistors on the output. Sending this config will enabale
+ *	push-pull mode, the argument is ignored.
+ * @PIN_CONFIG_DRIVE_OPEN_DRAIN: the pin will be driven with open drain (open
+ *	collector) which means it is usually wired with other output ports
+ *	which are then pulled up with an external resistor. Sending this
+ *	config will enabale open drain mode, the argument is ignored.
+ * @PIN_CONFIG_DRIVE_OPEN_SOURCE: the pin will be driven with open source
+ *	(open emitter). Sending this config will enabale open drain mode, the
+ *	argument is ignored.
+ * @PIN_CONFIG_INPUT_SCHMITT: this will configure an input pin to run in
+ *	schmitt-trigger mode. If the schmitt-trigger has adjustable hysteresis,
+ *	the threshold value is given on a custom format as argument when
+ *	setting pins to this mode. The argument zero turns the schmitt trigger
+ *	off.
+ * @PIN_CONFIG_INPUT_DEBOUNCE: this will configure the pin to debounce mode,
+ *	which means it will wait for signals to settle when reading inputs. The
+ *	argument gives the debounce time on a custom format. Setting the
+ *	argument to zero turns debouncing off.
+ * @PIN_CONFIG_POWER_SOURCE: if the pin can select between different power
+ *	supplies, the argument to this parameter (on a custom format) tells
+ *	the driver which alternative power source to use.
+ * @PIN_CONFIG_LOW_POWER_MODE: this will configure the pin for low power
+ *	operation, if several modes of operation are supported these can be
+ *	passed in the argument on a custom form, else just use argument 1
+ *	to indicate low power mode, argument 0 turns low power mode off.
+ * @PIN_CONFIG_END: this is the last enumerator for pin configurations, if
+ *	you need to pass in custom configurations to the pin controller, use
+ *	PIN_CONFIG_END+1 as the base offset.
+ */
+enum pin_config_param {
+	PIN_CONFIG_BIAS_DISABLE,
+	PIN_CONFIG_BIAS_HIGH_IMPEDANCE,
+	PIN_CONFIG_BIAS_PULL_UP,
+	PIN_CONFIG_BIAS_PULL_DOWN,
+	PIN_CONFIG_DRIVE_PUSH_PULL,
+	PIN_CONFIG_DRIVE_OPEN_DRAIN,
+	PIN_CONFIG_DRIVE_OPEN_SOURCE,
+	PIN_CONFIG_INPUT_SCHMITT,
+	PIN_CONFIG_INPUT_DEBOUNCE,
+	PIN_CONFIG_POWER_SOURCE,
+	PIN_CONFIG_LOW_POWER_MODE,
+	PIN_CONFIG_END = 0x7FFF,
+};
+
+/*
+ * Helpful configuration macro to be used in tables etc.
+ */
+#define PIN_CONF_PACKED(p, a) ((a << 16) | ((unsigned long) p & 0xffffUL))
+
+/*
+ * The following inlines stuffs a configuration parameter and data value
+ * into and out of an unsigned long argument, as used by the generic pin config
+ * system. We put the parameter in the lower 16 bits and the argument in the
+ * upper 16 bits.
+ */
+
+static inline enum pin_config_param pinconf_to_config_param(unsigned long config)
+{
+	return (enum pin_config_param) (config & 0xffffUL);
+}
+
+static inline u16 pinconf_to_config_argument(unsigned long config)
+{
+	return (enum pin_config_param) ((config >> 16) & 0xffffUL);
+}
+
+static inline unsigned long pinconf_to_config_packed(enum pin_config_param param,
+						     u16 argument)
+{
+	return PIN_CONF_PACKED(param, argument);
+}
+
+#endif /* CONFIG_GENERIC_PINCONF */
+
+#endif /* __LINUX_PINCTRL_PINCONF_GENERIC_H */

include/linux/pinctrl/pinconf.h

···
 /**
  * struct pinconf_ops - pin config operations, to be implemented by
  * pin configuration capable drivers.
+ * @is_generic: for pin controllers that want to use the generic interface,
+ *	this flag tells the framework that it's generic.
  * @pin_config_get: get the config of a certain pin, if the requested config
  *	is not available on this controller this should return -ENOTSUPP
  *	and if it is available but disabled it should return -EINVAL
···
  *	per-device info for a certain group in debugfs
  */
 struct pinconf_ops {
+#ifdef CONFIG_GENERIC_PINCONF
+	bool is_generic;
+#endif
 	int (*pin_config_get) (struct pinctrl_dev *pctldev,
 			       unsigned pin,
 			       unsigned long *config);