Merge tag 'reset-for-v6.9' of git://git.pengutronix.de/pza/linux into soc/late

Reset controller updates for v6.9

Enable support for the Sophgo SG2042 reset controller via reset-simple,
add a GPIO-based reset controller criver for shared GPIO resets, extract
an of_phandle_args_equal() helper function out of cpufreq, and use it in
reset-gpio.

Based on v6.8-rc5 because reset-gpio depends on commits in the
gpio-driver-h-stubs-for-v6.8-rc5 tag.

* tag 'reset-for-v6.9' of git://git.pengutronix.de/pza/linux:
  reset: Instantiate reset GPIO controller for shared reset-gpios
  reset: gpio: Add GPIO-based reset controller
  cpufreq: do not open-code of_phandle_args_equal()
  of: Add of_phandle_args_equal() helper
  reset: simple: add support for Sophgo SG2042
  dt-bindings: reset: sophgo: support SG2042

Link: https://lore.kernel.org/r/20240301111300.4038207-1-p.zabel@pengutronix.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: arndb

Documentation/devicetree/bindings/reset/sophgo,sg2042-reset.yaml

@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/reset/sophgo,sg2042-reset.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sophgo SG2042 SoC Reset Controller
+
+maintainers:
+  - Chen Wang <unicorn_wang@outlook.com>
+
+properties:
+  compatible:
+    const: sophgo,sg2042-reset
+
+  reg:
+    maxItems: 1
+
+  "#reset-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - "#reset-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    rstgen: reset-controller@c00 {
+        compatible = "sophgo,sg2042-reset";
+        reg = <0xc00 0xc>;
+        #reset-cells = <1>;
+    };

MAINTAINERS

@@ -8911,6 +8911,11 @@ F:	Documentation/i2c/muxes/i2c-mux-gpio.rst
 F:	drivers/i2c/muxes/i2c-mux-gpio.c
 F:	include/linux/platform_data/i2c-mux-gpio.h
 
+GENERIC GPIO RESET DRIVER
+M:	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
+S:	Maintained
+F:	drivers/reset/reset-gpio.c
+
 GENERIC HDLC (WAN) DRIVERS
 M:	Krzysztof Halasa <khc@pm.waw.pl>
 S:	Maintained

drivers/reset/Kconfig

@@ -66,6 +66,15 @@ config RESET_BRCMSTB_RESCAL
 	  This enables the RESCAL reset controller for SATA, PCIe0, or PCIe1 on
 	  BCM7216.
 
+config RESET_GPIO
+	tristate "GPIO reset controller"
+	help
+	  This enables a generic reset controller for resets attached via
+	  GPIOs.  Typically for OF platforms this driver expects "reset-gpios"
+	  property.
+
+	  If compiled as module, it will be called reset-gpio.
+
 config RESET_HSDK
 	bool "Synopsys HSDK Reset Driver"
 	depends on HAS_IOMEM
@@ -213,7 +222,7 @@ config RESET_SCMI
 
 config RESET_SIMPLE
 	bool "Simple Reset Controller Driver" if COMPILE_TEST || EXPERT
-	default ARCH_ASPEED || ARCH_BCMBCA || ARCH_BITMAIN || ARCH_REALTEK || ARCH_STM32 || (ARCH_INTEL_SOCFPGA && ARM64) || ARCH_SUNXI || ARC
+	default ARCH_ASPEED || ARCH_BCMBCA || ARCH_BITMAIN || ARCH_REALTEK || ARCH_SOPHGO || ARCH_STM32 || (ARCH_INTEL_SOCFPGA && ARM64) || ARCH_SUNXI || ARC
 	depends on HAS_IOMEM
 	help
 	  This enables a simple reset controller driver for reset lines that
@@ -228,6 +237,7 @@ config RESET_SIMPLE
 	   - RCC reset controller in STM32 MCUs
 	   - Allwinner SoCs
 	   - SiFive FU740 SoCs
+	   - Sophgo SoCs
 
 config RESET_SOCFPGA
 	bool "SoCFPGA Reset Driver" if COMPILE_TEST && (!ARM || !ARCH_INTEL_SOCFPGA)

drivers/reset/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
 obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
 obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
 obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
+obj-$(CONFIG_RESET_GPIO) += reset-gpio.o
 obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
 obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
 obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o

drivers/reset/core.c

@@ -5,14 +5,19 @@
  * Copyright 2013 Philipp Zabel, Pengutronix
  */
 #include <linux/atomic.h>
+#include <linux/cleanup.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/kref.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/machine.h>
+#include <linux/idr.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/acpi.h>
+#include <linux/platform_device.h>
 #include <linux/reset.h>
 #include <linux/reset-controller.h>
 #include <linux/slab.h>
@@ -23,6 +28,11 @@ static LIST_HEAD(reset_controller_list);
 static DEFINE_MUTEX(reset_lookup_mutex);
 static LIST_HEAD(reset_lookup_list);
 
+/* Protects reset_gpio_lookup_list */
+static DEFINE_MUTEX(reset_gpio_lookup_mutex);
+static LIST_HEAD(reset_gpio_lookup_list);
+static DEFINE_IDA(reset_gpio_ida);
+
 /**
  * struct reset_control - a reset control
  * @rcdev: a pointer to the reset controller device
@@ -63,6 +73,16 @@ struct reset_control_array {
 	struct reset_control *rstc[] __counted_by(num_rstcs);
 };
 
+/**
+ * struct reset_gpio_lookup - lookup key for ad-hoc created reset-gpio devices
+ * @of_args: phandle to the reset controller with all the args like GPIO number
+ * @list: list entry for the reset_gpio_lookup_list
+ */
+struct reset_gpio_lookup {
+	struct of_phandle_args of_args;
+	struct list_head list;
+};
+
 static const char *rcdev_name(struct reset_controller_dev *rcdev)
 {
 	if (rcdev->dev)
@@ -71,6 +91,9 @@ static const char *rcdev_name(struct reset_controller_dev *rcdev)
 	if (rcdev->of_node)
 		return rcdev->of_node->full_name;
 
+	if (rcdev->of_args)
+		return rcdev->of_args->np->full_name;
+
 	return NULL;
 }
 
@@ -99,6 +122,9 @@ static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
  */
 int reset_controller_register(struct reset_controller_dev *rcdev)
 {
+	if (rcdev->of_node && rcdev->of_args)
+		return -EINVAL;
+
 	if (!rcdev->of_xlate) {
 		rcdev->of_reset_n_cells = 1;
 		rcdev->of_xlate = of_reset_simple_xlate;
@@ -813,12 +839,171 @@ static void __reset_control_put_internal(struct reset_control *rstc)
 	kref_put(&rstc->refcnt, __reset_control_release);
 }
 
+static int __reset_add_reset_gpio_lookup(int id, struct device_node *np,
+					 unsigned int gpio,
+					 unsigned int of_flags)
+{
+	const struct fwnode_handle *fwnode = of_fwnode_handle(np);
+	unsigned int lookup_flags;
+	const char *label_tmp;
+
+	/*
+	 * Later we map GPIO flags between OF and Linux, however not all
+	 * constants from include/dt-bindings/gpio/gpio.h and
+	 * include/linux/gpio/machine.h match each other.
+	 */
+	if (of_flags > GPIO_ACTIVE_LOW) {
+		pr_err("reset-gpio code does not support GPIO flags %u for GPIO %u\n",
+		       of_flags, gpio);
+		return -EINVAL;
+	}
+
+	struct gpio_device *gdev __free(gpio_device_put) = gpio_device_find_by_fwnode(fwnode);
+	if (!gdev)
+		return -EPROBE_DEFER;
+
+	label_tmp = gpio_device_get_label(gdev);
+	if (!label_tmp)
+		return -EINVAL;
+
+	char *label __free(kfree) = kstrdup(label_tmp, GFP_KERNEL);
+	if (!label)
+		return -ENOMEM;
+
+	/* Size: one lookup entry plus sentinel */
+	struct gpiod_lookup_table *lookup __free(kfree) = kzalloc(struct_size(lookup, table, 2),
+								  GFP_KERNEL);
+	if (!lookup)
+		return -ENOMEM;
+
+	lookup->dev_id = kasprintf(GFP_KERNEL, "reset-gpio.%d", id);
+	if (!lookup->dev_id)
+		return -ENOMEM;
+
+	lookup_flags = GPIO_PERSISTENT;
+	lookup_flags |= of_flags & GPIO_ACTIVE_LOW;
+	lookup->table[0] = GPIO_LOOKUP(no_free_ptr(label), gpio, "reset",
+				       lookup_flags);
+
+	/* Not freed on success, because it is persisent subsystem data. */
+	gpiod_add_lookup_table(no_free_ptr(lookup));
+
+	return 0;
+}
+
+/*
+ * @args:	phandle to the GPIO provider with all the args like GPIO number
+ */
+static int __reset_add_reset_gpio_device(const struct of_phandle_args *args)
+{
+	struct reset_gpio_lookup *rgpio_dev;
+	struct platform_device *pdev;
+	int id, ret;
+
+	/*
+	 * Currently only #gpio-cells=2 is supported with the meaning of:
+	 * args[0]: GPIO number
+	 * args[1]: GPIO flags
+	 * TODO: Handle other cases.
+	 */
+	if (args->args_count != 2)
+		return -ENOENT;
+
+	/*
+	 * Registering reset-gpio device might cause immediate
+	 * bind, resulting in its probe() registering new reset controller thus
+	 * taking reset_list_mutex lock via reset_controller_register().
+	 */
+	lockdep_assert_not_held(&reset_list_mutex);
+
+	mutex_lock(&reset_gpio_lookup_mutex);
+
+	list_for_each_entry(rgpio_dev, &reset_gpio_lookup_list, list) {
+		if (args->np == rgpio_dev->of_args.np) {
+			if (of_phandle_args_equal(args, &rgpio_dev->of_args))
+				goto out; /* Already on the list, done */
+		}
+	}
+
+	id = ida_alloc(&reset_gpio_ida, GFP_KERNEL);
+	if (id < 0) {
+		ret = id;
+		goto err_unlock;
+	}
+
+	/* Not freed on success, because it is persisent subsystem data. */
+	rgpio_dev = kzalloc(sizeof(*rgpio_dev), GFP_KERNEL);
+	if (!rgpio_dev) {
+		ret = -ENOMEM;
+		goto err_ida_free;
+	}
+
+	ret = __reset_add_reset_gpio_lookup(id, args->np, args->args[0],
+					    args->args[1]);
+	if (ret < 0)
+		goto err_kfree;
+
+	rgpio_dev->of_args = *args;
+	/*
+	 * We keep the device_node reference, but of_args.np is put at the end
+	 * of __of_reset_control_get(), so get it one more time.
+	 * Hold reference as long as rgpio_dev memory is valid.
+	 */
+	of_node_get(rgpio_dev->of_args.np);
+	pdev = platform_device_register_data(NULL, "reset-gpio", id,
+					     &rgpio_dev->of_args,
+					     sizeof(rgpio_dev->of_args));
+	ret = PTR_ERR_OR_ZERO(pdev);
+	if (ret)
+		goto err_put;
+
+	list_add(&rgpio_dev->list, &reset_gpio_lookup_list);
+
+out:
+	mutex_unlock(&reset_gpio_lookup_mutex);
+
+	return 0;
+
+err_put:
+	of_node_put(rgpio_dev->of_args.np);
+err_kfree:
+	kfree(rgpio_dev);
+err_ida_free:
+	ida_free(&reset_gpio_ida, id);
+err_unlock:
+	mutex_unlock(&reset_gpio_lookup_mutex);
+
+	return ret;
+}
+
+static struct reset_controller_dev *__reset_find_rcdev(const struct of_phandle_args *args,
+						       bool gpio_fallback)
+{
+	struct reset_controller_dev *rcdev;
+
+	lockdep_assert_held(&reset_list_mutex);
+
+	list_for_each_entry(rcdev, &reset_controller_list, list) {
+		if (gpio_fallback) {
+			if (rcdev->of_args && of_phandle_args_equal(args,
+								    rcdev->of_args))
+				return rcdev;
+		} else {
+			if (args->np == rcdev->of_node)
+				return rcdev;
+		}
+	}
+
+	return NULL;
+}
+
 struct reset_control *
 __of_reset_control_get(struct device_node *node, const char *id, int index,
 		       bool shared, bool optional, bool acquired)
 {
+	bool gpio_fallback = false;
 	struct reset_control *rstc;
-	struct reset_controller_dev *r, *rcdev;
+	struct reset_controller_dev *rcdev;
 	struct of_phandle_args args;
 	int rstc_id;
 	int ret;
@@ -839,39 +1024,52 @@ __of_reset_control_get(struct device_node *node, const char *id, int index,
 					 index, &args);
 	if (ret == -EINVAL)
 		return ERR_PTR(ret);
-	if (ret)
-		return optional ? NULL : ERR_PTR(ret);
+	if (ret) {
+		if (!IS_ENABLED(CONFIG_RESET_GPIO))
+			return optional ? NULL : ERR_PTR(ret);
 
-	mutex_lock(&reset_list_mutex);
-	rcdev = NULL;
-	list_for_each_entry(r, &reset_controller_list, list) {
-		if (args.np == r->of_node) {
-			rcdev = r;
-			break;
+		/*
+		 * There can be only one reset-gpio for regular devices, so
+		 * don't bother with the "reset-gpios" phandle index.
+		 */
+		ret = of_parse_phandle_with_args(node, "reset-gpios", "#gpio-cells",
+						 0, &args);
+		if (ret)
+			return optional ? NULL : ERR_PTR(ret);
+
+		gpio_fallback = true;
+
+		ret = __reset_add_reset_gpio_device(&args);
+		if (ret) {
+			rstc = ERR_PTR(ret);
+			goto out_put;
 		}
 	}
 
+	mutex_lock(&reset_list_mutex);
+	rcdev = __reset_find_rcdev(&args, gpio_fallback);
 	if (!rcdev) {
 		rstc = ERR_PTR(-EPROBE_DEFER);
-		goto out;
+		goto out_unlock;
 	}
 
 	if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
 		rstc = ERR_PTR(-EINVAL);
-		goto out;
+		goto out_unlock;
 	}
 
 	rstc_id = rcdev->of_xlate(rcdev, &args);
 	if (rstc_id < 0) {
 		rstc = ERR_PTR(rstc_id);
-		goto out;
+		goto out_unlock;
 	}
 
 	/* reset_list_mutex also protects the rcdev's reset_control list */
 	rstc = __reset_control_get_internal(rcdev, rstc_id, shared, acquired);
 
-out:
+out_unlock:
 	mutex_unlock(&reset_list_mutex);
+out_put:
 	of_node_put(args.np);
 
 	return rstc;