Add bridged amplifiers to cs42l43

Merge series from Charles Keepax <[email protected]>:

In some cs42l43 systems a couple of cs35l56 amplifiers are attached
to the cs42l43's SPI and I2S. On Windows the cs42l43 is controlled
by a SDCA class driver and these two amplifiers are controlled by
firmware running on the cs42l43. However, under Linux the decision
was made to interact with the cs42l43 directly, affording the user
greater control over the audio system. However, this has resulted
in an issue where these two bridged cs35l56 amplifiers are not
populated in ACPI and must be added manually. There is at least an
SDCA extension unit DT entry we can key off.

The process of adding this is handled using a software node, firstly the
ability to add native chip selects to software nodes must be added.
Secondly, an additional flag for naming the SPI devices is added this
allows the machine driver to key to the correct amplifier. Then finally,
the cs42l43 SPI driver adds the two amplifiers directly onto its SPI
bus.

An additional series will follow soon to add the audio machine driver
parts (in the sof-sdw driver), however that is fairly orthogonal to
this part of the process, getting the actual amplifiers registered.

4 files changed, 124 insertions, 22 deletions

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b50d0b470849..00b5c007a2bb 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -103,6 +103,15 @@ config GPIO_REGMAP
 	select REGMAP
 	tristate
 
+config GPIO_SWNODE_UNDEFINED
+	bool
+	help
+	  This adds a special place holder for software nodes to contain an
+	  undefined GPIO reference, this is primarily used by SPI to allow a
+	  list of GPIO chip selects to mark a certain chip select as being
+	  controlled the SPI device's internal chip select mechanism and not
+	  a GPIO.
+
 # put drivers in the right section, in alphabetical order
 
 # This symbol is selected by both I2C and SPI expanders
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index f384fa278764..d09c7d728365 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -728,6 +728,25 @@ static u32 line_event_id(int level)
 		       GPIO_V2_LINE_EVENT_FALLING_EDGE;
 }
 
+static inline char *make_irq_label(const char *orig)
+{
+	char *new;
+
+	if (!orig)
+		return NULL;
+
+	new = kstrdup_and_replace(orig, '/', ':', GFP_KERNEL);
+	if (!new)
+		return ERR_PTR(-ENOMEM);
+
+	return new;
+}
+
+static inline void free_irq_label(const char *label)
+{
+	kfree(label);
+}
+
 #ifdef CONFIG_HTE
 
 static enum hte_return process_hw_ts_thread(void *p)
@@ -1015,6 +1034,7 @@ static int debounce_setup(struct line *line, unsigned int debounce_period_us)
 {
 	unsigned long irqflags;
 	int ret, level, irq;
+	char *label;
 
 	/* try hardware */
 	ret = gpiod_set_debounce(line->desc, debounce_period_us);
@@ -1037,11 +1057,17 @@ static int debounce_setup(struct line *line, unsigned int debounce_period_us)
 			if (irq < 0)
 				return -ENXIO;
 
+			label = make_irq_label(line->req->label);
+			if (IS_ERR(label))
+				return -ENOMEM;
+
 			irqflags = IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING;
 			ret = request_irq(irq, debounce_irq_handler, irqflags,
-					  line->req->label, line);
-			if (ret)
+					  label, line);
+			if (ret) {
+				free_irq_label(label);
 				return ret;
+			}
 			line->irq = irq;
 		} else {
 			ret = hte_edge_setup(line, GPIO_V2_LINE_FLAG_EDGE_BOTH);
@@ -1086,7 +1112,7 @@ static u32 gpio_v2_line_config_debounce_period(struct gpio_v2_line_config *lc,
 static void edge_detector_stop(struct line *line)
 {
 	if (line->irq) {
-		free_irq(line->irq, line);
+		free_irq_label(free_irq(line->irq, line));
 		line->irq = 0;
 	}
 
@@ -1110,6 +1136,7 @@ static int edge_detector_setup(struct line *line,
 	unsigned long irqflags = 0;
 	u64 eflags;
 	int irq, ret;
+	char *label;
 
 	eflags = edflags & GPIO_V2_LINE_EDGE_FLAGS;
 	if (eflags && !kfifo_initialized(&line->req->events)) {
@@ -1146,11 +1173,17 @@ static int edge_detector_setup(struct line *line,
 			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
 	irqflags |= IRQF_ONESHOT;
 
+	label = make_irq_label(line->req->label);
+	if (IS_ERR(label))
+		return PTR_ERR(label);
+
 	/* Request a thread to read the events */
 	ret = request_threaded_irq(irq, edge_irq_handler, edge_irq_thread,
-				   irqflags, line->req->label, line);
-	if (ret)
+				   irqflags, label, line);
+	if (ret) {
+		free_irq_label(label);
 		return ret;
+	}
 
 	line->irq = irq;
 	return 0;
@@ -1973,7 +2006,7 @@ static void lineevent_free(struct lineevent_state *le)
 		blocking_notifier_chain_unregister(&le->gdev->device_notifier,
 						   &le->device_unregistered_nb);
 	if (le->irq)
-		free_irq(le->irq, le);
+		free_irq_label(free_irq(le->irq, le));
 	if (le->desc)
 		gpiod_free(le->desc);
 	kfree(le->label);
@@ -2114,6 +2147,7 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	int fd;
 	int ret;
 	int irq, irqflags = 0;
+	char *label;
 
 	if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
 		return -EFAULT;
@@ -2198,15 +2232,23 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 	if (ret)
 		goto out_free_le;
 
+	label = make_irq_label(le->label);
+	if (IS_ERR(label)) {
+		ret = PTR_ERR(label);
+		goto out_free_le;
+	}
+
 	/* Request a thread to read the events */
 	ret = request_threaded_irq(irq,
 				   lineevent_irq_handler,
 				   lineevent_irq_thread,
 				   irqflags,
-				   le->label,
+				   label,
 				   le);
-	if (ret)
+	if (ret) {
+		free_irq_label(label);
 		goto out_free_le;
+	}
 
 	le->irq = irq;
 
diff --git a/drivers/gpio/gpiolib-swnode.c b/drivers/gpio/gpiolib-swnode.c
index fa52bdb1a29a..cec1ab878af8 100644
--- a/drivers/gpio/gpiolib-swnode.c
+++ b/drivers/gpio/gpiolib-swnode.c
@@ -4,8 +4,13 @@
  *
  * Copyright 2022 Google LLC
  */
+
+#define pr_fmt(fmt) "gpiolib: swnode: " fmt
+
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/printk.h>
 #include <linux/property.h>
@@ -17,6 +22,8 @@
 #include "gpiolib.h"
 #include "gpiolib-swnode.h"
 
+#define GPIOLIB_SWNODE_UNDEFINED_NAME "swnode-gpio-undefined"
+
 static void swnode_format_propname(const char *con_id, char *propname,
 				   size_t max_size)
 {
@@ -40,6 +47,14 @@ static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
 	if (!gdev_node || !gdev_node->name)
 		return ERR_PTR(-EINVAL);
 
+	/*
+	 * Check for a special node that identifies undefined GPIOs, this is
+	 * primarily used as a key for internal chip selects in SPI bindings.
+	 */
+	if (IS_ENABLED(CONFIG_GPIO_SWNODE_UNDEFINED) &&
+	    !strcmp(gdev_node->name, GPIOLIB_SWNODE_UNDEFINED_NAME))
+		return ERR_PTR(-ENOENT);
+
 	gdev = gpio_device_find_by_label(gdev_node->name);
 	return gdev ?: ERR_PTR(-EPROBE_DEFER);
 }
@@ -121,3 +136,32 @@ int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
 
 	return count ?: -ENOENT;
 }
+
+#if IS_ENABLED(CONFIG_GPIO_SWNODE_UNDEFINED)
+/*
+ * A special node that identifies undefined GPIOs, this is primarily used as
+ * a key for internal chip selects in SPI bindings.
+ */
+const struct software_node swnode_gpio_undefined = {
+	.name = GPIOLIB_SWNODE_UNDEFINED_NAME,
+};
+EXPORT_SYMBOL_NS_GPL(swnode_gpio_undefined, GPIO_SWNODE);
+
+static int __init swnode_gpio_init(void)
+{
+	int ret;
+
+	ret = software_node_register(&swnode_gpio_undefined);
+	if (ret < 0)
+		pr_err("failed to register swnode: %d\n", ret);
+
+	return ret;
+}
+subsys_initcall(swnode_gpio_init);
+
+static void __exit swnode_gpio_cleanup(void)
+{
+	software_node_unregister(&swnode_gpio_undefined);
+}
+__exitcall(swnode_gpio_cleanup);
+#endif
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index ce94e37bcbee..94903fc1c145 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1175,6 +1175,9 @@ struct gpio_device *gpio_device_find(const void *data,
 
 	list_for_each_entry_srcu(gdev, &gpio_devices, list,
 				 srcu_read_lock_held(&gpio_devices_srcu)) {
+		if (!device_is_registered(&gdev->dev))
+			continue;
+
 		guard(srcu)(&gdev->srcu);
 
 		gc = srcu_dereference(gdev->chip, &gdev->srcu);
@@ -2397,6 +2400,11 @@ char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
 }
 EXPORT_SYMBOL_GPL(gpiochip_dup_line_label);
 
+static inline const char *function_name_or_default(const char *con_id)
+{
+	return con_id ?: "(default)";
+}
+
 /**
  * gpiochip_request_own_desc - Allow GPIO chip to request its own descriptor
  * @gc: GPIO chip
@@ -2425,10 +2433,11 @@ struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc,
 					    enum gpiod_flags dflags)
 {
 	struct gpio_desc *desc = gpiochip_get_desc(gc, hwnum);
+	const char *name = function_name_or_default(label);
 	int ret;
 
 	if (IS_ERR(desc)) {
-		chip_err(gc, "failed to get GPIO descriptor\n");
+		chip_err(gc, "failed to get GPIO %s descriptor\n", name);
 		return desc;
 	}
 
@@ -2438,8 +2447,8 @@ struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc,
 
 	ret = gpiod_configure_flags(desc, label, lflags, dflags);
 	if (ret) {
-		chip_err(gc, "setup of own GPIO %s failed\n", label);
 		gpiod_free_commit(desc);
+		chip_err(gc, "setup of own GPIO %s failed\n", name);
 		return ERR_PTR(ret);
 	}
 
@@ -4153,19 +4162,17 @@ static struct gpio_desc *gpiod_find_by_fwnode(struct fwnode_handle *fwnode,
 					      enum gpiod_flags *flags,
 					      unsigned long *lookupflags)
 {
+	const char *name = function_name_or_default(con_id);
 	struct gpio_desc *desc = ERR_PTR(-ENOENT);
 
 	if (is_of_node(fwnode)) {
-		dev_dbg(consumer, "using DT '%pfw' for '%s' GPIO lookup\n",
-			fwnode, con_id);
+		dev_dbg(consumer, "using DT '%pfw' for '%s' GPIO lookup\n", fwnode, name);
 		desc = of_find_gpio(to_of_node(fwnode), con_id, idx, lookupflags);
 	} else if (is_acpi_node(fwnode)) {
-		dev_dbg(consumer, "using ACPI '%pfw' for '%s' GPIO lookup\n",
-			fwnode, con_id);
+		dev_dbg(consumer, "using ACPI '%pfw' for '%s' GPIO lookup\n", fwnode, name);
 		desc = acpi_find_gpio(fwnode, con_id, idx, flags, lookupflags);
 	} else if (is_software_node(fwnode)) {
-		dev_dbg(consumer, "using swnode '%pfw' for '%s' GPIO lookup\n",
-			fwnode, con_id);
+		dev_dbg(consumer, "using swnode '%pfw' for '%s' GPIO lookup\n", fwnode, name);
 		desc = swnode_find_gpio(fwnode, con_id, idx, lookupflags);
 	}
 
@@ -4181,6 +4188,7 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer,
 					 bool platform_lookup_allowed)
 {
 	unsigned long lookupflags = GPIO_LOOKUP_FLAGS_DEFAULT;
+	const char *name = function_name_or_default(con_id);
 	/*
 	 * scoped_guard() is implemented as a for loop, meaning static
 	 * analyzers will complain about these two not being initialized.
@@ -4203,8 +4211,7 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer,
 		}
 
 		if (IS_ERR(desc)) {
-			dev_dbg(consumer, "No GPIO consumer %s found\n",
-				con_id);
+			dev_dbg(consumer, "No GPIO consumer %s found\n", name);
 			return desc;
 		}
 
@@ -4226,15 +4233,14 @@ struct gpio_desc *gpiod_find_and_request(struct device *consumer,
 		 *
 		 * FIXME: Make this more sane and safe.
 		 */
-		dev_info(consumer,
-			 "nonexclusive access to GPIO for %s\n", con_id);
+		dev_info(consumer, "nonexclusive access to GPIO for %s\n", name);
 		return desc;
 	}
 
 	ret = gpiod_configure_flags(desc, con_id, lookupflags, flags);
 	if (ret < 0) {
-		dev_dbg(consumer, "setup of GPIO %s failed\n", con_id);
 		gpiod_put(desc);
+		dev_dbg(consumer, "setup of GPIO %s failed\n", name);
 		return ERR_PTR(ret);
 	}
 
@@ -4350,6 +4356,7 @@ EXPORT_SYMBOL_GPL(gpiod_get_optional);
 int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id,
 		unsigned long lflags, enum gpiod_flags dflags)
 {
+	const char *name = function_name_or_default(con_id);
 	int ret;
 
 	if (lflags & GPIO_ACTIVE_LOW)
@@ -4393,7 +4400,7 @@ int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id,
 
 	/* No particular flag request, return here... */
 	if (!(dflags & GPIOD_FLAGS_BIT_DIR_SET)) {
-		gpiod_dbg(desc, "no flags found for %s\n", con_id);
+		gpiod_dbg(desc, "no flags found for GPIO %s\n", name);
 		return 0;
 	}