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        <noltari@gmail.com>
To:     p.zabel@pengutronix.de, robh+dt@kernel.org,
        tsbogend@alpha.franken.de, f.fainelli@gmail.com,
        jonas.gorski@gmail.com, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
        bcm-kernel-feedback-list@broadcom.com
Cc:     =?UTF-8?q?=C3=81lvaro=20Fern=C3=A1ndez=20Rojas?= 
        <noltari@gmail.com>, Florian Fainelli <F.fainelli@gmail.com>
Subject: [PATCH v7 3/9] reset: add BCM6345 reset controller driver
Date:   Wed, 17 Jun 2020 12:50:35 +0200
Message-Id: <20200617105042.3824116-4-noltari@gmail.com>
In-Reply-To: <20200617105042.3824116-1-noltari@gmail.com>
References: <20200617105042.3824116-1-noltari@gmail.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Add support for resetting blocks through the Linux reset controller
subsystem for BCM63xx SoCs.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Florian Fainelli <F.fainelli@gmail.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 v7: introduce changes suggested by Philipp:
     - sort Kconfig alphabetically.
     - return 0 on bcm6345_reset_update.
     - add second sleep comment.
 v6: driver improvements:
     - use devm_platform_ioremap_resource.
     - simplify bcm6345_reset_probe return.
     - introduce and use to_bcm6345_reset function.
 v5: fix kbuild robot error (drop __init).
 v4: no changes.
 v3: using reset-simple isn't possible since sleeping after performing the
     reset is also needed.
 v2: add compatibility to reset-simple instead of adding a new driver.

 drivers/reset/Kconfig         |   7 ++
 drivers/reset/Makefile        |   1 +
 drivers/reset/reset-bcm6345.c | 135 ++++++++++++++++++++++++++++++++++
 3 files changed, 143 insertions(+)
 create mode 100644 drivers/reset/reset-bcm6345.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index d9efbfd29646..6b9625a40799 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -35,6 +35,13 @@ config RESET_AXS10X
 	help
 	  This enables the reset controller driver for AXS10x.
 
+config RESET_BCM6345
+	bool "BCM6345 Reset Controller"
+	depends on BMIPS_GENERIC || COMPILE_TEST
+	default BMIPS_GENERIC
+	help
+	  This enables the reset controller driver for BCM6345 SoCs.
+
 config RESET_BERLIN
 	bool "Berlin Reset Driver" if COMPILE_TEST
 	default ARCH_BERLIN
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 249ed357c997..e642aae42f0f 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_ARCH_TEGRA) += tegra/
 obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
 obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
 obj-$(CONFIG_RESET_AXS10X) += reset-axs10x.o
+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
diff --git a/drivers/reset/reset-bcm6345.c b/drivers/reset/reset-bcm6345.c
new file mode 100644
index 000000000000..737e4e81f6b7
--- /dev/null
+++ b/drivers/reset/reset-bcm6345.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * BCM6345 Reset Controller Driver
+ *
+ * Copyright (C) 2020 Álvaro Fernández Rojas <noltari@gmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#define BCM6345_RESET_NUM		32
+#define BCM6345_RESET_SLEEP_MIN_US	10000
+#define BCM6345_RESET_SLEEP_MAX_US	20000
+
+struct bcm6345_reset {
+	struct reset_controller_dev rcdev;
+	void __iomem *base;
+	spinlock_t lock;
+};
+
+static inline struct bcm6345_reset *
+to_bcm6345_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct bcm6345_reset, rcdev);
+}
+
+static int bcm6345_reset_update(struct reset_controller_dev *rcdev,
+				unsigned long id, bool assert)
+{
+	struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
+	unsigned long flags;
+	uint32_t val;
+
+	spin_lock_irqsave(&bcm6345_reset->lock, flags);
+	val = __raw_readl(bcm6345_reset->base);
+	if (assert)
+		val &= ~BIT(id);
+	else
+		val |= BIT(id);
+	__raw_writel(val, bcm6345_reset->base);
+	spin_unlock_irqrestore(&bcm6345_reset->lock, flags);
+
+	return 0;
+}
+
+static int bcm6345_reset_assert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	return bcm6345_reset_update(rcdev, id, true);
+}
+
+static int bcm6345_reset_deassert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	return bcm6345_reset_update(rcdev, id, false);
+}
+
+static int bcm6345_reset_reset(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	bcm6345_reset_update(rcdev, id, true);
+	usleep_range(BCM6345_RESET_SLEEP_MIN_US,
+		     BCM6345_RESET_SLEEP_MAX_US);
+
+	bcm6345_reset_update(rcdev, id, false);
+	/*
+	 * Ensure component is taken out reset state by sleeping also after
+	 * deasserting the reset. Otherwise, the component may not be ready
+	 * for operation.
+	 */
+	usleep_range(BCM6345_RESET_SLEEP_MIN_US,
+		     BCM6345_RESET_SLEEP_MAX_US);
+
+	return 0;
+}
+
+static int bcm6345_reset_status(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct bcm6345_reset *bcm6345_reset = to_bcm6345_reset(rcdev);
+
+	return !(__raw_readl(bcm6345_reset->base) & BIT(id));
+}
+
+static struct reset_control_ops bcm6345_reset_ops = {
+	.assert = bcm6345_reset_assert,
+	.deassert = bcm6345_reset_deassert,
+	.reset = bcm6345_reset_reset,
+	.status = bcm6345_reset_status,
+};
+
+static int bcm6345_reset_probe(struct platform_device *pdev)
+{
+	struct bcm6345_reset *bcm6345_reset;
+
+	bcm6345_reset = devm_kzalloc(&pdev->dev,
+				     sizeof(*bcm6345_reset), GFP_KERNEL);
+	if (!bcm6345_reset)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, bcm6345_reset);
+
+	bcm6345_reset->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(bcm6345_reset->base))
+		return PTR_ERR(bcm6345_reset->base);
+
+	spin_lock_init(&bcm6345_reset->lock);
+	bcm6345_reset->rcdev.ops = &bcm6345_reset_ops;
+	bcm6345_reset->rcdev.owner = THIS_MODULE;
+	bcm6345_reset->rcdev.of_node = pdev->dev.of_node;
+	bcm6345_reset->rcdev.of_reset_n_cells = 1;
+	bcm6345_reset->rcdev.nr_resets = BCM6345_RESET_NUM;
+
+	return devm_reset_controller_register(&pdev->dev,
+					      &bcm6345_reset->rcdev);
+}
+
+static const struct of_device_id bcm6345_reset_of_match[] = {
+	{ .compatible = "brcm,bcm6345-reset" },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver bcm6345_reset_driver = {
+	.probe = bcm6345_reset_probe,
+	.driver	= {
+		.name = "bcm6345-reset",
+		.of_match_table = bcm6345_reset_of_match,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver(bcm6345_reset_driver);
-- 
2.27.0