[PATCH v2 1/1] gpiolib: of: add gpio-line node support

[James Hilliard <james.hilliard1@gmail.com>]

Allow GPIO controller child nodes marked with "gpio-line" to
configure direction/flags at probe time without hogging the line.

Teach OF gpiochip scanning and OF dynamic reconfiguration handlers to
process gpio-line nodes in addition to gpio-hog nodes.

Also parse "gpio-line-name" and apply it to desc->name. For gpio-hog
nodes, keep "line-name" semantics as the hog consumer label.

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
Depends on:
  - https://github.com/devicetree-org/dt-schema/pull/185

Changes v1 -> v2:
  - drop documentation changes
  - add depends on to changelog
---
 drivers/gpio/gpiolib-of.c     | 89 ++++++++++++++++++++++++++++-------
 drivers/gpio/gpiolib-shared.c |  7 +--
 drivers/of/property.c         |  7 +--
 scripts/dtc/checks.c          |  4 +-
 4 files changed, 82 insertions(+), 25 deletions(-)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index ef1ac68b94b7..b10a21a63d46 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -744,6 +744,7 @@ struct gpio_desc *of_find_gpio(struct device_node *np, const char *con_id,
  * @lflags:	bitmask of gpio_lookup_flags GPIO_* values - returned from
  *		of_find_gpio() or of_parse_own_gpio()
  * @dflags:	gpiod_flags - optional GPIO initialization flags
+ * @hog:	indicates if this is a gpio-hog node
  *
  * Returns:
  * GPIO descriptor to use with Linux GPIO API, or one of the errno
@@ -753,11 +754,13 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
 					   struct gpio_chip *chip,
 					   unsigned int idx, const char **name,
 					   unsigned long *lflags,
-					   enum gpiod_flags *dflags)
+					   enum gpiod_flags *dflags,
+					   bool hog)
 {
 	struct device_node *chip_np;
 	enum of_gpio_flags xlate_flags;
 	struct of_phandle_args gpiospec;
+	const char *desc_name;
 	struct gpio_desc *desc;
 	unsigned int i;
 	u32 tmp;
@@ -797,15 +800,19 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
 		*dflags |= GPIOD_OUT_LOW;
 	else if (of_property_read_bool(np, "output-high"))
 		*dflags |= GPIOD_OUT_HIGH;
-	else {
+	else if (hog) {
 		pr_warn("GPIO line %d (%pOFn): no hogging state specified, bailing out\n",
 			desc_to_gpio(desc), np);
 		return ERR_PTR(-EINVAL);
 	}
 
-	if (name && of_property_read_string(np, "line-name", name))
+	if (hog && name && of_property_read_string(np, "line-name", name))
 		*name = np->name;
 
+	if (!of_property_read_string(np, "gpio-line-name", &desc_name) &&
+	    desc_name[0])
+		desc->name = desc_name;
+
 	return desc;
 }
 
@@ -827,7 +834,8 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
 	int ret;
 
 	for (i = 0;; i++) {
-		desc = of_parse_own_gpio(hog, chip, i, &name, &lflags, &dflags);
+		desc = of_parse_own_gpio(hog, chip, i, &name, &lflags, &dflags,
+					 true);
 		if (IS_ERR(desc))
 			break;
 
@@ -843,6 +851,36 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
 	return 0;
 }
 
+/**
+ * of_gpiochip_add_line - Configure all lines in a gpio-line device node
+ * @chip:	gpio chip to act on
+ * @line:	device node describing GPIO lines to configure
+ *
+ * Returns:
+ * 0 on success, or negative errno on failure.
+ */
+static int of_gpiochip_add_line(struct gpio_chip *chip, struct device_node *line)
+{
+	enum gpiod_flags dflags;
+	struct gpio_desc *desc;
+	unsigned long lflags;
+	unsigned int i;
+	int ret;
+
+	for (i = 0;; i++) {
+		desc = of_parse_own_gpio(line, chip, i, NULL, &lflags, &dflags,
+					 false);
+		if (IS_ERR(desc))
+			break;
+
+		ret = gpiod_configure_flags(desc, NULL, lflags, dflags);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
 /**
  * of_gpiochip_scan_gpios - Scan gpio-controller for gpio definitions
  * @chip:	gpio chip to act on
@@ -858,14 +896,22 @@ static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
 	int ret;
 
 	for_each_available_child_of_node_scoped(dev_of_node(&chip->gpiodev->dev), np) {
-		if (!of_property_read_bool(np, "gpio-hog"))
+		if (of_property_read_bool(np, "gpio-hog")) {
+			ret = of_gpiochip_add_hog(chip, np);
+			if (ret < 0)
+				return ret;
+
+			of_node_set_flag(np, OF_POPULATED);
 			continue;
+		}
 
-		ret = of_gpiochip_add_hog(chip, np);
-		if (ret < 0)
-			return ret;
+		if (of_property_read_bool(np, "gpio-line")) {
+			ret = of_gpiochip_add_line(chip, np);
+			if (ret < 0)
+				return ret;
 
-		of_node_set_flag(np, OF_POPULATED);
+			of_node_set_flag(np, OF_POPULATED);
+		}
 	}
 
 	return 0;
@@ -905,14 +951,15 @@ static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 	int ret;
 
 	/*
-	 * This only supports adding and removing complete gpio-hog nodes.
-	 * Modifying an existing gpio-hog node is not supported (except for
-	 * changing its "status" property, which is treated the same as
-	 * addition/removal).
+	 * This only supports adding and removing complete gpio-hog and
+	 * gpio-line nodes. Modifying an existing node is not supported
+	 * (except for changing its "status" property, which is treated
+	 * the same as addition/removal).
 	 */
 	switch (of_reconfig_get_state_change(action, arg)) {
 	case OF_RECONFIG_CHANGE_ADD:
-		if (!of_property_read_bool(rd->dn, "gpio-hog"))
+		if (!of_property_read_bool(rd->dn, "gpio-hog") &&
+		    !of_property_read_bool(rd->dn, "gpio-line"))
 			return NOTIFY_DONE;	/* not for us */
 
 		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED))
@@ -922,9 +969,12 @@ static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 		if (!gdev)
 			return NOTIFY_DONE;	/* not for us */
 
-		ret = of_gpiochip_add_hog(gpio_device_get_chip(gdev), rd->dn);
+		if (of_property_read_bool(rd->dn, "gpio-hog"))
+			ret = of_gpiochip_add_hog(gpio_device_get_chip(gdev), rd->dn);
+		else
+			ret = of_gpiochip_add_line(gpio_device_get_chip(gdev), rd->dn);
 		if (ret < 0) {
-			pr_err("%s: failed to add hogs for %pOF\n", __func__,
+			pr_err("%s: failed to configure lines for %pOF\n", __func__,
 			       rd->dn);
 			of_node_clear_flag(rd->dn, OF_POPULATED);
 			return notifier_from_errno(ret);
@@ -932,6 +982,10 @@ static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 		return NOTIFY_OK;
 
 	case OF_RECONFIG_CHANGE_REMOVE:
+		if (!of_property_read_bool(rd->dn, "gpio-hog") &&
+		    !of_property_read_bool(rd->dn, "gpio-line"))
+			return NOTIFY_DONE;	/* not for us */
+
 		if (!of_node_check_flag(rd->dn, OF_POPULATED))
 			return NOTIFY_DONE;	/* already depopulated */
 
@@ -939,7 +993,8 @@ static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 		if (!gdev)
 			return NOTIFY_DONE;	/* not for us */
 
-		of_gpiochip_remove_hog(gpio_device_get_chip(gdev), rd->dn);
+		if (of_property_read_bool(rd->dn, "gpio-hog"))
+			of_gpiochip_remove_hog(gpio_device_get_chip(gdev), rd->dn);
 		of_node_clear_flag(rd->dn, OF_POPULATED);
 		return NOTIFY_OK;
 	}
diff --git a/drivers/gpio/gpiolib-shared.c b/drivers/gpio/gpiolib-shared.c
index b3525d1f06a4..b934e58a07f0 100644
--- a/drivers/gpio/gpiolib-shared.c
+++ b/drivers/gpio/gpiolib-shared.c
@@ -147,10 +147,11 @@ static bool gpio_shared_of_node_ignore(struct device_node *node)
 		return true;
 
 	/*
-	 * GPIO hogs have a "gpios" property which is not a phandle and can't
-	 * possibly refer to a shared GPIO.
+	 * GPIO hog and gpio-line nodes have a "gpios" property which is not a
+	 * phandle and can't possibly refer to a shared GPIO.
 	 */
-	if (of_property_present(node, "gpio-hog"))
+	if (of_property_present(node, "gpio-hog") ||
+	    of_property_present(node, "gpio-line"))
 		return true;
 
 	return false;
diff --git a/drivers/of/property.c b/drivers/of/property.c
index 50d95d512bf5..7689c4315115 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1435,10 +1435,11 @@ static struct device_node *parse_gpio_compat(struct device_node *np,
 		return NULL;
 
 	/*
-	 * Ignore node with gpio-hog property since its gpios are all provided
-	 * by its parent.
+	 * Ignore nodes with gpio-hog and gpio-line properties since their gpios
+	 * are all provided by their parent.
 	 */
-	if (of_property_read_bool(np, "gpio-hog"))
+	if (of_property_read_bool(np, "gpio-hog") ||
+	    of_property_read_bool(np, "gpio-line"))
 		return NULL;
 
 	if (of_parse_phandle_with_args(np, prop_name, "#gpio-cells", index,
diff --git a/scripts/dtc/checks.c b/scripts/dtc/checks.c
index 45d0213f3bf3..ee64cb4ada4f 100644
--- a/scripts/dtc/checks.c
+++ b/scripts/dtc/checks.c
@@ -1533,8 +1533,8 @@ static void check_gpios_property(struct check *c,
 {
 	struct property *prop;
 
-	/* Skip GPIO hog nodes which have 'gpios' property */
-	if (get_property(node, "gpio-hog"))
+	/* Skip gpio-hog and gpio-line nodes which have 'gpios' property */
+	if (get_property(node, "gpio-hog") || get_property(node, "gpio-line"))
 		return;
 
 	for_each_property(node, prop) {
-- 
2.43.0