[PATCH v8 12/12] mux: support simplified bindings for single-user gpio mux

[Peter Rosin <peda@axentia.se>]

Allow bindings for a GPIO controlled mux to be specified in the
mux consumer node.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
 drivers/mux/Kconfig    |  5 +----
 drivers/mux/mux-core.c | 23 +++++++++++++++++++++--
 drivers/mux/mux-gpio.c | 28 +++++++++++++++++++++-------
 drivers/mux/mux-gpio.h | 13 +++++++++++++
 4 files changed, 56 insertions(+), 13 deletions(-)
 create mode 100644 drivers/mux/mux-gpio.h

diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
index d13fcf98958e..cd161c228537 100644
--- a/drivers/mux/Kconfig
+++ b/drivers/mux/Kconfig
@@ -29,7 +29,7 @@ config MUX_ADG792A
 	  be called mux-adg792a.
 
 config MUX_GPIO
-	tristate "GPIO-controlled Multiplexer"
+	bool "GPIO-controlled Multiplexer"
 	depends on OF && GPIOLIB
 	help
 	  GPIO-controlled Multiplexer controller.
@@ -39,7 +39,4 @@ config MUX_GPIO
 	  states. The GPIO pins can be connected (by the hardware) to several
 	  multiplexers, which in that case will be operated in parallel.
 
-	  To compile the driver as a module, choose M here: the module will
-	  be called mux-gpio.
-
 endif
diff --git a/drivers/mux/mux-core.c b/drivers/mux/mux-core.c
index 16a61253d164..0caafd6f5a77 100644
--- a/drivers/mux/mux-core.c
+++ b/drivers/mux/mux-core.c
@@ -21,6 +21,8 @@
 #include <linux/of_platform.h>
 #include <linux/slab.h>
 
+#include "mux-gpio.h"
+
 static struct class mux_class = {
 	.name = "mux",
 	.owner = THIS_MODULE,
@@ -314,9 +316,26 @@ struct mux_control *mux_control_get(struct device *dev, const char *mux_name)
 	ret = of_parse_phandle_with_args(np,
 					 "mux-controls", "#mux-control-cells",
 					 index, &args);
+
+#ifdef CONFIG_MUX_GPIO
+	if (ret == -ENOENT && !mux_name) {
+		mux_chip = mux_gpio_alloc(dev);
+		if (!IS_ERR(mux_chip)) {
+			ret = devm_mux_chip_register(dev, mux_chip);
+			if (ret < 0)
+				return ERR_PTR(ret);
+			get_device(&mux_chip->dev);
+			return mux_chip->mux;
+		}
+
+		ret = PTR_ERR(mux_chip);
+	}
+#endif
+
 	if (ret) {
-		dev_err(dev, "%s: failed to get mux-control %s(%i)\n",
-			np->full_name, mux_name ?: "", index);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "%s: failed to get mux-control %s(%i)\n",
+				np->full_name, mux_name ?: "", index);
 		return ERR_PTR(ret);
 	}
 
diff --git a/drivers/mux/mux-gpio.c b/drivers/mux/mux-gpio.c
index 48ca4d6b4fc7..2ab8735e3415 100644
--- a/drivers/mux/mux-gpio.c
+++ b/drivers/mux/mux-gpio.c
@@ -18,6 +18,8 @@
 #include <linux/platform_device.h>
 #include <linux/property.h>
 
+#include "mux-gpio.h"
+
 struct mux_gpio {
 	struct gpio_descs *gpios;
 	int *val;
@@ -48,24 +50,21 @@ static const struct of_device_id mux_gpio_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);
 
-static int mux_gpio_probe(struct platform_device *pdev)
+struct mux_chip *mux_gpio_alloc(struct device *dev)
 {
-	struct device *dev = &pdev->dev;
-	struct device_node *np = dev->of_node;
 	struct mux_chip *mux_chip;
 	struct mux_gpio *mux_gpio;
 	int pins;
-	u32 idle_state;
 	int ret;
 
 	pins = gpiod_count(dev, "mux");
 	if (pins < 0)
-		return pins;
+		return ERR_PTR(pins);
 
 	mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio) +
 				       pins * sizeof(*mux_gpio->val));
 	if (!mux_chip)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	mux_gpio = mux_chip_priv(mux_chip);
 	mux_gpio->val = (int *)(mux_gpio + 1);
@@ -76,11 +75,26 @@ static int mux_gpio_probe(struct platform_device *pdev)
 		ret = PTR_ERR(mux_gpio->gpios);
 		if (ret != -EPROBE_DEFER)
 			dev_err(dev, "failed to get gpios\n");
-		return ret;
+		return ERR_PTR(ret);
 	}
 	WARN_ON(pins != mux_gpio->gpios->ndescs);
 	mux_chip->mux->states = 1 << pins;
 
+	return mux_chip;
+}
+EXPORT_SYMBOL_GPL(mux_gpio_alloc);
+
+static int mux_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mux_chip *mux_chip;
+	u32 idle_state;
+	int ret;
+
+	mux_chip = mux_gpio_alloc(dev);
+	if (IS_ERR(mux_chip))
+		return PTR_ERR(mux_chip);
+
 	ret = device_property_read_u32(dev, "idle-state", &idle_state);
 	if (ret >= 0) {
 		if (idle_state >= mux_chip->mux->states) {
diff --git a/drivers/mux/mux-gpio.h b/drivers/mux/mux-gpio.h
new file mode 100644
index 000000000000..fe3e8d0173aa
--- /dev/null
+++ b/drivers/mux/mux-gpio.h
@@ -0,0 +1,13 @@
+/*
+ * GPIO-controlled multiplexer driver interface
+ *
+ * Copyright (C) 2017 Axentia Technologies AB
+ *
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * 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.
+ */
+
+struct mux_chip *mux_gpio_alloc(struct device *dev);
-- 
2.1.4