Input: of_keymap - add device tree bindings for simple key matrices

This adds a simple device tree binding for simple key matrix data and
a helper to fill in the platform data.

Signed-off-by: Olof Johansson <[e-mail]>
Acked-by: Stephen Warren <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/matrix-keymap.txt

···
+A simple common binding for matrix-connected key boards. Currently targeted at
+defining the keys in the scope of linux key codes since that is a stable and
+standardized interface at this time.
+
+Required properties:
+- linux,keymap: an array of packed 1-cell entries containing the equivalent
+  of row, column and linux key-code. The 32-bit big endian cell is packed
+  as:
+	row << 24 | column << 16 | key-code
+
+Optional properties:
+Some users of this binding might choose to specify secondary keymaps for
+cases where there is a modifier key such as a Fn key. Proposed names
+for said properties are "linux,fn-keymap" or with another descriptive
+word for the modifier other from "Fn".
+
+Example:
+	linux,keymap = < 0x00030012
+			 0x0102003a >;

drivers/input/Kconfig

···
 
 if INPUT
 
+config INPUT_OF_MATRIX_KEYMAP
+	depends on USE_OF
+	bool
+
 config INPUT_FF_MEMLESS
 	tristate "Support for memoryless force-feedback devices"
 	help

drivers/input/Makefile

···
 obj-$(CONFIG_INPUT_MISC)	+= misc/
 
 obj-$(CONFIG_INPUT_APMPOWER)	+= apm-power.o
+obj-$(CONFIG_INPUT_OF_MATRIX_KEYMAP) += of_keymap.o

drivers/input/keyboard/Kconfig

···
 config KEYBOARD_TEGRA
 	tristate "NVIDIA Tegra internal matrix keyboard controller support"
 	depends on ARCH_TEGRA
+	select INPUT_OF_MATRIX_KEYMAP if USE_OF
 	help
 	  Say Y here if you want to use a matrix keyboard connected directly
 	  to the internal keyboard controller on Tegra SoCs.

drivers/input/of_keymap.c

···
+/*
+ * Helpers for open firmware matrix keyboard bindings
+ *
+ * Copyright (C) 2012 Google, Inc
+ *
+ * Author:
+ *	Olof Johansson <[e-mail]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/kernel.h>
+#include <linux/types.h>
+#include <linux/input.h>
+#include <linux/of.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+
+struct matrix_keymap_data *
+matrix_keyboard_of_fill_keymap(struct device_node *np,
+			       const char *propname)
+{
+	struct matrix_keymap_data *kd;
+	u32 *keymap;
+	int proplen, i;
+	const __be32 *prop;
+
+	if (!np)
+		return NULL;
+
+	if (!propname)
+		propname = "linux,keymap";
+
+	prop = of_get_property(np, propname, &proplen);
+	if (!prop)
+		return NULL;
+
+	if (proplen % sizeof(u32)) {
+		pr_warn("Malformed keymap property %s in %s\n",
+			propname, np->full_name);
+		return NULL;
+	}
+
+	kd = kzalloc(sizeof(*kd), GFP_KERNEL);
+	if (!kd)
+		return NULL;
+
+	kd->keymap = keymap = kzalloc(proplen, GFP_KERNEL);
+	if (!kd->keymap) {
+		kfree(kd);
+		return NULL;
+	}
+
+	kd->keymap_size = proplen / sizeof(u32);
+
+	for (i = 0; i < kd->keymap_size; i++) {
+		u32 tmp = be32_to_cpup(prop + i);
+		int key_code, row, col;
+
+		row = (tmp >> 24) & 0xff;
+		col = (tmp >> 16) & 0xff;
+		key_code = tmp & 0xffff;
+		keymap[i] = KEY(row, col, key_code);
+	}
+
+	return kd;
+}
+EXPORT_SYMBOL_GPL(matrix_keyboard_of_fill_keymap);
+
+void matrix_keyboard_of_free_keymap(const struct matrix_keymap_data *kd)
+{
+	if (kd) {
+		kfree(kd->keymap);
+		kfree(kd);
+	}
+}
+EXPORT_SYMBOL_GPL(matrix_keyboard_of_free_keymap);

include/linux/input/matrix_keypad.h

···
 
 #include <linux/types.h>
 #include <linux/input.h>
+#include <linux/of.h>
 
 #define MATRIX_MAX_ROWS		32
 #define MATRIX_MAX_COLS		32
···
 	}
 	__clear_bit(KEY_RESERVED, keybit);
 }
+
+#ifdef CONFIG_INPUT_OF_MATRIX_KEYMAP
+struct matrix_keymap_data *
+matrix_keyboard_of_fill_keymap(struct device_node *np, const char *propname);
+
+void matrix_keyboard_of_free_keymap(const struct matrix_keymap_data *kd);
+#else
+static inline struct matrix_keymap_data *
+matrix_keyboard_of_fill_keymap(struct device_node *np, const char *propname)
+{
+	return NULL;
+}
+
+static inline void
+matrix_keyboard_of_free_keymap(const struct matrix_keymap_data *kd)
+{
+}
+#endif
 
 #endif /* _MATRIX_KEYPAD_H */