[PATCH v3 10/13] of: add a generic pinmux helper

[Stephen Warren]

From: Jamie Iles <jamie@xxxxxxxxxxxxx>

This patch adds a helper function of_pinmux_parse() that can be used to
extract common pinmux configuration to avoid each platform implementing
a parsing loop.  Platforms supply the node containing the pinmux
definitions and a platform specific callback for configuring a pingroup.

Signed-off-by: Jamie Iles <jamie@xxxxxxxxxxxxx>
[swarren: Added support for pins property, added parse() callback, use
 dev_err instead of pr_err, related minor changes]
Signed-off-by: Stephen Warren <swarren@xxxxxxxxxx>
---
 drivers/of/Kconfig        |    5 ++
 drivers/of/Makefile       |    1 +
 drivers/of/of_pinmux.c    |  109 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_pinmux.h |   74 ++++++++++++++++++++++++++++++
 4 files changed, 189 insertions(+), 0 deletions(-)
 create mode 100644 drivers/of/of_pinmux.c
 create mode 100644 include/linux/of_pinmux.h

diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index cac63c9..71a19a3 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -81,4 +81,9 @@ config OF_PCI_IRQ
 	help
 	  OpenFirmware PCI IRQ routing helpers
 
+config OF_PINMUX
+	def_bool y
+	help
+	  OpenFirmware pin multiplexing helpers
+
 endmenu # OF
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index dccb117..0666ff3 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_OF_SPI)	+= of_spi.o
 obj-$(CONFIG_OF_MDIO)	+= of_mdio.o
 obj-$(CONFIG_OF_PCI)	+= of_pci.o
 obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
+obj-$(CONFIG_OF_PINMUX) += of_pinmux.o
diff --git a/drivers/of/of_pinmux.c b/drivers/of/of_pinmux.c
new file mode 100644
index 0000000..8050b8b
--- /dev/null
+++ b/drivers/of/of_pinmux.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2011 Picochip Ltd., Jamie Iles
+ * Copyright (c) 2011 NVIDIA, Inc.
+ *
+ * Generic pinmux bindings for device tree.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_iter_prop.h>
+#include <linux/of_pinmux.h>
+
+/**
+ * of_pinmux_parse - configure a set of pinmux groups for a pinmux controller
+ *
+ * @controller: the controller to configure the pinmux entries for.  This
+ *	defines the controller device node and the callback for configuring
+ *	the pingroups.
+ *
+ * This helper loops over all of the child nodes of a pinmux controller and
+ * collects the configuration for each pinmux group.  A pinmux group is
+ * defined as one or more pins that are configured to a common function.  This
+ * handles common properties that many platforms may implement, but for
+ * platform specific properties these may be handled in the configure
+ * callback.
+ */
+int of_pinmux_parse(const struct of_pinmux_ctrl *ctrl,
+		    struct of_pinmux_cfg *cfg)
+{
+	struct device_node *np;
+
+	if (!ctrl || !ctrl->dev || !ctrl->node || !ctrl->configure)
+		return -EINVAL;
+
+	for_each_child_of_node(ctrl->node, np) {
+		int ret;
+		bool hadpins = 0;
+		struct of_iter_string_prop iter;
+
+		cfg->node = np;
+
+		ret = of_property_read_string(np, "function",
+					      &cfg->function);
+		if (ret < 0) {
+			dev_err(ctrl->dev, "no function for node %s\n",
+				np->name);
+			continue;
+		}
+
+		cfg->flags &= 0;
+
+		if (of_find_property(np, "pull-up", NULL))
+			cfg->flags |= OF_PINMUX_PULL_UP;
+		if (of_find_property(np, "pull-down", NULL))
+			cfg->flags |= OF_PINMUX_PULL_DOWN;
+
+		if ((cfg->flags & OF_PINMUX_PULL_MASK) ==
+		    OF_PINMUX_PULL_MASK) {
+			dev_warn(ctrl->dev, "node %s has both "
+				 "pull-up and pull-down properties - "
+				 "defaulting to no pull\n",
+				 np->name);
+			cfg->flags &= ~OF_PINMUX_PULL_MASK;
+		}
+
+		if (of_find_property(np, "tristate", NULL))
+			cfg->flags |= OF_PINMUX_TRISTATE;
+
+		if (ctrl->parse && ctrl->parse(ctrl, cfg)) {
+			dev_warn(ctrl->dev,
+				    "failed to parse node %s\n",
+				    np->name);
+			continue;
+		}
+
+		for_each_string_property_value(iter, np, "pins") {
+			hadpins = 1;
+
+			cfg->pin = iter.value;
+
+			dev_dbg(ctrl->dev,
+				"configure pin %s func=%s flags=0x%lx\n",
+				cfg->pin, cfg->function, cfg->flags);
+			if (ctrl->configure(ctrl, cfg))
+				dev_warn(ctrl->dev,
+					 "failed to configure pin %s\n",
+					 cfg->pin);
+		}
+
+		if (!hadpins)
+			dev_warn(ctrl->dev, "no pins for node %s\n",
+				 np->name);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_pinmux_parse);
diff --git a/include/linux/of_pinmux.h b/include/linux/of_pinmux.h
new file mode 100644
index 0000000..7ccddcf
--- /dev/null
+++ b/include/linux/of_pinmux.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2011 Picochip Ltd., Jamie Iles
+ * Copyright (c) 2011 NVIDIA, Inc.
+ *
+ * Generic pinmux bindings for device tree.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#ifndef __OF_PINMUX_H__
+#define __OF_PINMUX_H__
+
+struct device_node;
+
+#define OF_PINMUX_PULL_UP	(1 << 0)
+#define OF_PINMUX_PULL_DOWN	(1 << 1)
+#define OF_PINMUX_TRISTATE	(1 << 2)
+
+#define OF_PINMUX_PULL_MASK	(OF_PINMUX_PULL_UP | OF_PINMUX_PULL_DOWN)
+
+/**
+ * struct of_pinmux_cfg - configuration state for a single pinmux entry.
+ *
+ * @function: the name of the function that the pinmux entry should be
+ *	configured to.
+ * @pin: the device_node of the pinmux entry that should be configured.
+ *	Platform specific properties that aren't in the generic binding may be
+ *	obtained from this device node.
+ * @flags: flags for common pinmux options such as pull and tristate.
+ */
+struct of_pinmux_cfg {
+	struct device_node	*node;
+	const char		*pin;
+	const char		*function;
+	unsigned long		flags;
+};
+
+/**
+ * struct of_pinmux_ctrl - platform specific pinmux control state.
+ *
+ * @pinmux: the pinmux device node.  All child nodes are required to be the
+ *	pinmux entry definitions.  Depending on the platform, this may either be
+ *	a single pin or a group of pins where they can be set to a common
+ *	function.
+ * @configure: platform specific callback to configure the pinmux entry.
+ */
+struct of_pinmux_ctrl {
+	struct device	   *dev;
+	struct device_node *node;
+	int		   (*parse)(const struct of_pinmux_ctrl *ctrl,
+				    struct of_pinmux_cfg *cfg);
+	int		   (*configure)(const struct of_pinmux_ctrl *ctrl,
+					const struct of_pinmux_cfg *cfg);
+};
+
+#ifdef CONFIG_OF
+extern int of_pinmux_parse(const struct of_pinmux_ctrl *ctrl,
+			   struct of_pinmux_cfg *cfg);
+#else
+static inline int of_pinmux_parse(const struct of_pinmux_ctrl *ctrl,
+				  struct of_pinmux_cfg *cfg)
+{
+	return -ENOSYS;
+}
+#endif /* CONFIG_OF */
+
+#endif /* __OF_PINMUX_H__ */
-- 
1.7.0.4

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