hwspinlock updates for v5.14

This adds a driver for the hardware spinlock in Allwinner sun6i.
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Merge tag 'hwlock-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/andersson/remoteproc

Pull hwspinlock updates from Bjorn Andersson:
 "This adds a driver for the hardware spinlock in Allwinner sun6i"

* tag 'hwlock-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/andersson/remoteproc:
  dt-bindings: hwlock: sun6i: Fix various warnings in binding
  hwspinlock: add sun6i hardware spinlock support
  dt-bindings: hwlock: add sun6i_hwspinlock

Documentation/devicetree/bindings/hwlock/allwinner,sun6i-a31-hwspinlock.yaml

@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwlock/allwinner,sun6i-a31-hwspinlock.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SUN6I hardware spinlock driver for Allwinner sun6i compatible SoCs
+
+maintainers:
+  - Wilken Gottwalt <wilken.gottwalt@posteo.net>
+
+description:
+  The hardware unit provides semaphores between the ARM cores and the embedded
+  companion core on the SoC.
+
+properties:
+  compatible:
+    const: allwinner,sun6i-a31-hwspinlock
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - resets
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/sun8i-a23-a33-ccu.h>
+    #include <dt-bindings/reset/sun8i-a23-a33-ccu.h>
+
+    hwlock@1c18000 {
+        compatible = "allwinner,sun6i-a31-hwspinlock";
+        reg = <0x01c18000 0x1000>;
+        clocks = <&ccu CLK_BUS_SPINLOCK>;
+        resets = <&ccu RST_BUS_SPINLOCK>;
+    };
+...

MAINTAINERS

@@ -752,6 +752,12 @@ L:	linux-crypto@vger.kernel.org
 S:	Maintained
 F:	drivers/crypto/allwinner/
 
+ALLWINNER HARDWARE SPINLOCK SUPPORT
+M:	Wilken Gottwalt <wilken.gottwalt@posteo.net>
+S:	Maintained
+F:	Documentation/devicetree/bindings/hwlock/allwinner,sun6i-hwspinlock.yaml
+F:	drivers/hwspinlock/sun6i_hwspinlock.c
+
 ALLWINNER THERMAL DRIVER
 M:	Vasily Khoruzhick <anarsoul@gmail.com>
 M:	Yangtao Li <tiny.windzz@gmail.com>

drivers/hwspinlock/Kconfig

@@ -44,6 +44,15 @@ config HWSPINLOCK_STM32
 
 	  If unsure, say N.
 
+config HWSPINLOCK_SUN6I
+	tristate "SUN6I Hardware Spinlock device"
+	depends on ARCH_SUNXI || COMPILE_TEST
+	help
+	  Say y here to support the SUN6I Hardware Spinlock device which can be
+	  found in most of the sun6i compatible Allwinner SoCs.
+
+	  If unsure, say N.
+
 config HSEM_U8500
 	tristate "STE Hardware Semaphore functionality"
 	depends on ARCH_U8500 || COMPILE_TEST

drivers/hwspinlock/Makefile

@@ -8,4 +8,5 @@ obj-$(CONFIG_HWSPINLOCK_OMAP)		+= omap_hwspinlock.o
 obj-$(CONFIG_HWSPINLOCK_QCOM)		+= qcom_hwspinlock.o
 obj-$(CONFIG_HWSPINLOCK_SPRD)		+= sprd_hwspinlock.o
 obj-$(CONFIG_HWSPINLOCK_STM32)		+= stm32_hwspinlock.o
+obj-$(CONFIG_HWSPINLOCK_SUN6I)		+= sun6i_hwspinlock.o
 obj-$(CONFIG_HSEM_U8500)		+= u8500_hsem.o

drivers/hwspinlock/sun6i_hwspinlock.c

@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * sun6i_hwspinlock.c - hardware spinlock driver for sun6i compatible Allwinner SoCs
+ * Copyright (C) 2020 Wilken Gottwalt <wilken.gottwalt@posteo.net>
+ */
+
+#include <linux/clk.h>
+#include <linux/debugfs.h>
+#include <linux/errno.h>
+#include <linux/hwspinlock.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include "hwspinlock_internal.h"
+
+#define DRIVER_NAME		"sun6i_hwspinlock"
+
+#define SPINLOCK_BASE_ID	0 /* there is only one hwspinlock device per SoC */
+#define SPINLOCK_SYSSTATUS_REG	0x0000
+#define SPINLOCK_LOCK_REGN	0x0100
+#define SPINLOCK_NOTTAKEN	0
+
+struct sun6i_hwspinlock_data {
+	struct hwspinlock_device *bank;
+	struct reset_control *reset;
+	struct clk *ahb_clk;
+	struct dentry *debugfs;
+	int nlocks;
+};
+
+#ifdef CONFIG_DEBUG_FS
+
+static int hwlocks_supported_show(struct seq_file *seqf, void *unused)
+{
+	struct sun6i_hwspinlock_data *priv = seqf->private;
+
+	seq_printf(seqf, "%d\n", priv->nlocks);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(hwlocks_supported);
+
+static void sun6i_hwspinlock_debugfs_init(struct sun6i_hwspinlock_data *priv)
+{
+	priv->debugfs = debugfs_create_dir(DRIVER_NAME, NULL);
+	debugfs_create_file("supported", 0444, priv->debugfs, priv, &hwlocks_supported_fops);
+}
+
+#else
+
+static void sun6i_hwspinlock_debugfs_init(struct sun6i_hwspinlock_data *priv)
+{
+}
+
+#endif
+
+static int sun6i_hwspinlock_trylock(struct hwspinlock *lock)
+{
+	void __iomem *lock_addr = lock->priv;
+
+	return (readl(lock_addr) == SPINLOCK_NOTTAKEN);
+}
+
+static void sun6i_hwspinlock_unlock(struct hwspinlock *lock)
+{
+	void __iomem *lock_addr = lock->priv;
+
+	writel(SPINLOCK_NOTTAKEN, lock_addr);
+}
+
+static const struct hwspinlock_ops sun6i_hwspinlock_ops = {
+	.trylock	= sun6i_hwspinlock_trylock,
+	.unlock		= sun6i_hwspinlock_unlock,
+};
+
+static void sun6i_hwspinlock_disable(void *data)
+{
+	struct sun6i_hwspinlock_data *priv = data;
+
+	debugfs_remove_recursive(priv->debugfs);
+	clk_disable_unprepare(priv->ahb_clk);
+	reset_control_assert(priv->reset);
+}
+
+static int sun6i_hwspinlock_probe(struct platform_device *pdev)
+{
+	struct sun6i_hwspinlock_data *priv;
+	struct hwspinlock *hwlock;
+	void __iomem *io_base;
+	u32 num_banks;
+	int err, i;
+
+	io_base = devm_platform_ioremap_resource(pdev, SPINLOCK_BASE_ID);
+	if (IS_ERR(io_base))
+		return PTR_ERR(io_base);
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->ahb_clk = devm_clk_get(&pdev->dev, "ahb");
+	if (IS_ERR(priv->ahb_clk)) {
+		err = PTR_ERR(priv->ahb_clk);
+		dev_err(&pdev->dev, "unable to get AHB clock (%d)\n", err);
+		return err;
+	}
+
+	priv->reset = devm_reset_control_get(&pdev->dev, "ahb");
+	if (IS_ERR(priv->reset))
+		return dev_err_probe(&pdev->dev, PTR_ERR(priv->reset),
+				     "unable to get reset control\n");
+
+	err = reset_control_deassert(priv->reset);
+	if (err) {
+		dev_err(&pdev->dev, "deassert reset control failure (%d)\n", err);
+		return err;
+	}
+
+	err = clk_prepare_enable(priv->ahb_clk);
+	if (err) {
+		dev_err(&pdev->dev, "unable to prepare AHB clk (%d)\n", err);
+		goto clk_fail;
+	}
+
+	/*
+	 * bit 28 and 29 represents the hwspinlock setup
+	 *
+	 * every datasheet (A64, A80, A83T, H3, H5, H6 ...) says the default value is 0x1 and 0x1
+	 * to 0x4 represent 32, 64, 128 and 256 locks
+	 * but later datasheets (H5, H6) say 00, 01, 10, 11 represent 32, 64, 128 and 256 locks,
+	 * but that would mean H5 and H6 have 64 locks, while their datasheets talk about 32 locks
+	 * all the time, not a single mentioning of 64 locks
+	 * the 0x4 value is also not representable by 2 bits alone, so some datasheets are not
+	 * correct
+	 * one thing have all in common, default value of the sysstatus register is 0x10000000,
+	 * which results in bit 28 being set
+	 * this is the reason 0x1 is considered being 32 locks and bit 30 is taken into account
+	 * verified on H2+ (datasheet 0x1 = 32 locks) and H5 (datasheet 01 = 64 locks)
+	 */
+	num_banks = readl(io_base + SPINLOCK_SYSSTATUS_REG) >> 28;
+	switch (num_banks) {
+	case 1 ... 4:
+		priv->nlocks = 1 << (4 + num_banks);
+		break;
+	default:
+		err = -EINVAL;
+		dev_err(&pdev->dev, "unsupported hwspinlock setup (%d)\n", num_banks);
+		goto bank_fail;
+	}
+
+	priv->bank = devm_kzalloc(&pdev->dev, struct_size(priv->bank, lock, priv->nlocks),
+				  GFP_KERNEL);
+	if (!priv->bank) {
+		err = -ENOMEM;
+		goto bank_fail;
+	}
+
+	for (i = 0; i < priv->nlocks; ++i) {
+		hwlock = &priv->bank->lock[i];
+		hwlock->priv = io_base + SPINLOCK_LOCK_REGN + sizeof(u32) * i;
+	}
+
+	/* failure of debugfs is considered non-fatal */
+	sun6i_hwspinlock_debugfs_init(priv);
+	if (IS_ERR(priv->debugfs))
+		priv->debugfs = NULL;
+
+	err = devm_add_action_or_reset(&pdev->dev, sun6i_hwspinlock_disable, priv);
+	if (err) {
+		dev_err(&pdev->dev, "failed to add hwspinlock disable action\n");
+		goto bank_fail;
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	return devm_hwspin_lock_register(&pdev->dev, priv->bank, &sun6i_hwspinlock_ops,
+					 SPINLOCK_BASE_ID, priv->nlocks);
+
+bank_fail:
+	clk_disable_unprepare(priv->ahb_clk);
+clk_fail:
+	reset_control_assert(priv->reset);
+
+	return err;
+}
+
+static const struct of_device_id sun6i_hwspinlock_ids[] = {
+	{ .compatible = "allwinner,sun6i-a31-hwspinlock", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sun6i_hwspinlock_ids);
+
+static struct platform_driver sun6i_hwspinlock_driver = {
+	.probe	= sun6i_hwspinlock_probe,
+	.driver	= {
+		.name		= DRIVER_NAME,
+		.of_match_table	= sun6i_hwspinlock_ids,
+	},
+};
+module_platform_driver(sun6i_hwspinlock_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("SUN6I hardware spinlock driver");
+MODULE_AUTHOR("Wilken Gottwalt <wilken.gottwalt@posteo.net>");