Reset controller changes for v4.20

This adds a new driver for the PDC Global (Power Domain Controller)
 reset controller found on Qualcomm SDM845 SoCs, fixes a potential
 use-after-free issue in reset_controller_dev.of_xlate() callbacks
 from __of_reset_control_get(), and trivially fixes a documentation
 grammar issue.
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Merge tag 'reset-for-4.20' of git://git.pengutronix.de/git/pza/linux into next/drivers

Reset controller changes for v4.20

This adds a new driver for the PDC Global (Power Domain Controller)
reset controller found on Qualcomm SDM845 SoCs, fixes a potential
use-after-free issue in reset_controller_dev.of_xlate() callbacks
from __of_reset_control_get(), and trivially fixes a documentation
grammar issue.

* tag 'reset-for-4.20' of git://git.pengutronix.de/git/pza/linux:
  reset: Fix potential use-after-free in __of_reset_control_get()
  reset: qcom: PDC Global (Power Domain Controller) reset controller
  dt-bindings: reset: Add PDC Global binding for SDM845 SoCs
  reset: Grammar s/more then once/more than once/

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Documentation/devicetree/bindings/reset/qcom,pdc-global.txt

@@ -0,0 +1,52 @@
+PDC Global
+======================================
+
+This binding describes a reset-controller found on PDC-Global (Power Domain
+Controller) block for Qualcomm Technologies Inc SDM845 SoCs.
+
+Required properties:
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: must be:
+		    "qcom,sdm845-pdc-global"
+
+- reg:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: must specify the base address and size of the register
+	            space.
+
+- #reset-cells:
+	Usage: required
+	Value type: <uint>
+	Definition: must be 1; cell entry represents the reset index.
+
+Example:
+
+pdc_reset: reset-controller@b2e0000 {
+	compatible = "qcom,sdm845-pdc-global";
+	reg = <0xb2e0000 0x20000>;
+	#reset-cells = <1>;
+};
+
+PDC reset clients
+======================================
+
+Device nodes that need access to reset lines should
+specify them as a reset phandle in their corresponding node as
+specified in reset.txt.
+
+For a list of all valid reset indices see
+<dt-bindings/reset/qcom,sdm845-pdc.h>
+
+Example:
+
+modem-pil@4080000 {
+	...
+
+	resets = <&pdc_reset PDC_MODEM_SYNC_RESET>;
+	reset-names = "pdc_reset";
+
+	...
+};

drivers/reset/Kconfig

@@ -98,6 +98,15 @@ config RESET_QCOM_AOSS
 	  reset signals provided by AOSS for Modem, Venus, ADSP,
 	  GPU, Camera, Wireless, Display subsystem. Otherwise, say N.
 
+config RESET_QCOM_PDC
+	tristate "Qualcomm PDC Reset Driver"
+	depends on ARCH_QCOM || COMPILE_TEST
+	help
+	  This enables the PDC (Power Domain Controller) reset driver
+	  for Qualcomm Technologies Inc SDM845 SoCs. Say Y if you want
+	  to control reset signals provided by PDC for Modem, Compute,
+	  Display, GPU, Debug, AOP, Sensors, Audio, SP and APPS.
+
 config RESET_SIMPLE
 	bool "Simple Reset Controller Driver" if COMPILE_TEST
 	default ARCH_SOCFPGA || ARCH_STM32 || ARCH_STRATIX10 || ARCH_SUNXI || ARCH_ZX || ARCH_ASPEED

drivers/reset/Makefile

@@ -16,6 +16,7 @@ obj-$(CONFIG_RESET_MESON_AUDIO_ARB) += reset-meson-audio-arb.o
 obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
 obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
 obj-$(CONFIG_RESET_QCOM_AOSS) += reset-qcom-aoss.o
+obj-$(CONFIG_RESET_QCOM_PDC) += reset-qcom-pdc.o
 obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
 obj-$(CONFIG_RESET_STM32MP157) += reset-stm32mp1.o
 obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o

drivers/reset/core.c

@@ -496,28 +496,29 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
 			break;
 		}
 	}
-	of_node_put(args.np);
 
 	if (!rcdev) {
-		mutex_unlock(&reset_list_mutex);
+		rstc = ERR_PTR(-EPROBE_DEFER);
-		return ERR_PTR(-EPROBE_DEFER);
+		goto out;
 	}
 
 	if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) {
-		mutex_unlock(&reset_list_mutex);
+		rstc = ERR_PTR(-EINVAL);
-		return ERR_PTR(-EINVAL);
+		goto out;
 	}
 
 	rstc_id = rcdev->of_xlate(rcdev, &args);
 	if (rstc_id < 0) {
-		mutex_unlock(&reset_list_mutex);
+		rstc = ERR_PTR(rstc_id);
-		return ERR_PTR(rstc_id);
+		goto out;
 	}
 
 	/* reset_list_mutex also protects the rcdev's reset_control list */
 	rstc = __reset_control_get_internal(rcdev, rstc_id, shared);
 
+out:
 	mutex_unlock(&reset_list_mutex);
+	of_node_put(args.np);
 
 	return rstc;
 }

drivers/reset/reset-qcom-pdc.c

@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/reset/qcom,sdm845-pdc.h>
+
+#define RPMH_PDC_SYNC_RESET	0x100
+
+struct qcom_pdc_reset_map {
+	u8 bit;
+};
+
+struct qcom_pdc_reset_data {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+};
+
+static const struct regmap_config sdm845_pdc_regmap_config = {
+	.name		= "pdc-reset",
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.max_register	= 0x20000,
+	.fast_io	= true,
+};
+
+static const struct qcom_pdc_reset_map sdm845_pdc_resets[] = {
+	[PDC_APPS_SYNC_RESET] = {0},
+	[PDC_SP_SYNC_RESET] = {1},
+	[PDC_AUDIO_SYNC_RESET] = {2},
+	[PDC_SENSORS_SYNC_RESET] = {3},
+	[PDC_AOP_SYNC_RESET] = {4},
+	[PDC_DEBUG_SYNC_RESET] = {5},
+	[PDC_GPU_SYNC_RESET] = {6},
+	[PDC_DISPLAY_SYNC_RESET] = {7},
+	[PDC_COMPUTE_SYNC_RESET] = {8},
+	[PDC_MODEM_SYNC_RESET] = {9},
+};
+
+static inline struct qcom_pdc_reset_data *to_qcom_pdc_reset_data(
+				struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct qcom_pdc_reset_data, rcdev);
+}
+
+static int qcom_pdc_control_assert(struct reset_controller_dev *rcdev,
+					unsigned long idx)
+{
+	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
+
+	return regmap_update_bits(data->regmap, RPMH_PDC_SYNC_RESET,
+				  BIT(sdm845_pdc_resets[idx].bit),
+				  BIT(sdm845_pdc_resets[idx].bit));
+}
+
+static int qcom_pdc_control_deassert(struct reset_controller_dev *rcdev,
+					unsigned long idx)
+{
+	struct qcom_pdc_reset_data *data = to_qcom_pdc_reset_data(rcdev);
+
+	return regmap_update_bits(data->regmap, RPMH_PDC_SYNC_RESET,
+				  BIT(sdm845_pdc_resets[idx].bit), 0);
+}
+
+static const struct reset_control_ops qcom_pdc_reset_ops = {
+	.assert = qcom_pdc_control_assert,
+	.deassert = qcom_pdc_control_deassert,
+};
+
+static int qcom_pdc_reset_probe(struct platform_device *pdev)
+{
+	struct qcom_pdc_reset_data *data;
+	struct device *dev = &pdev->dev;
+	void __iomem *base;
+	struct resource *res;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	data->regmap = devm_regmap_init_mmio(dev, base,
+					     &sdm845_pdc_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(dev, "Unable to initialize regmap\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.ops = &qcom_pdc_reset_ops;
+	data->rcdev.nr_resets = ARRAY_SIZE(sdm845_pdc_resets);
+	data->rcdev.of_node = dev->of_node;
+
+	return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static const struct of_device_id qcom_pdc_reset_of_match[] = {
+	{ .compatible = "qcom,sdm845-pdc-global" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_pdc_reset_of_match);
+
+static struct platform_driver qcom_pdc_reset_driver = {
+	.probe = qcom_pdc_reset_probe,
+	.driver = {
+		.name = "qcom_pdc_reset",
+		.of_match_table = qcom_pdc_reset_of_match,
+	},
+};
+module_platform_driver(qcom_pdc_reset_driver);
+
+MODULE_DESCRIPTION("Qualcomm PDC Reset Driver");
+MODULE_LICENSE("GPL v2");

include/dt-bindings/reset/qcom,sdm845-pdc.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018 The Linux Foundation. All rights reserved.
+ */
+
+#ifndef _DT_BINDINGS_RESET_PDC_SDM_845_H
+#define _DT_BINDINGS_RESET_PDC_SDM_845_H
+
+#define PDC_APPS_SYNC_RESET	0
+#define PDC_SP_SYNC_RESET	1
+#define PDC_AUDIO_SYNC_RESET	2
+#define PDC_SENSORS_SYNC_RESET	3
+#define PDC_AOP_SYNC_RESET	4
+#define PDC_DEBUG_SYNC_RESET	5
+#define PDC_GPU_SYNC_RESET	6
+#define PDC_DISPLAY_SYNC_RESET	7
+#define PDC_COMPUTE_SYNC_RESET	8
+#define PDC_MODEM_SYNC_RESET	9
+
+#endif

include/linux/reset.h

@@ -116,7 +116,7 @@ static inline int device_reset_optional(struct device *dev)
  * @id: reset line name
  *
  * Returns a struct reset_control or IS_ERR() condition containing errno.
- * If this function is called more then once for the same reset_control it will
+ * If this function is called more than once for the same reset_control it will
  * return -EBUSY.
  *
  * See reset_control_get_shared for details on shared references to