reset: meson: add meson audio arb driver

The Amlogic Audio ARB is a simple device which enables or
disables the access of Audio FIFOs to DDR on AXG based SoC.

Signed-off-by: Jerome Brunet <[e-mail]>
Signed-off-by: Philipp Zabel <[e-mail]>

drivers/reset/Kconfig

···
 	help
 	  This enables the reset driver for Amlogic Meson SoCs.
 
+config RESET_MESON_AUDIO_ARB
+	tristate "Meson Audio Memory Arbiter Reset Driver"
+	depends on ARCH_MESON || COMPILE_TEST
+	help
+	  This enables the reset driver for Audio Memory Arbiter of
+	  Amlogic's A113 based SoCs
+
 config RESET_OXNAS
 	bool
 

drivers/reset/Makefile

···
 obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
 obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
 obj-$(CONFIG_RESET_MESON) += reset-meson.o
+obj-$(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

drivers/reset/reset-meson-audio-arb.c

···
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+// Copyright (c) 2018 BayLibre, SAS.
+// Author: Jerome Brunet <[e-mail]>
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/reset-controller.h>
+#include <linux/spinlock.h>
+
+#include <dt-bindings/reset/amlogic,meson-axg-audio-arb.h>
+
+struct meson_audio_arb_data {
+	struct reset_controller_dev rstc;
+	void __iomem *regs;
+	struct clk *clk;
+	const unsigned int *reset_bits;
+	spinlock_t lock;
+};
+
+#define ARB_GENERAL_BIT	31
+
+static const unsigned int axg_audio_arb_reset_bits[] = {
+	[AXG_ARB_TODDR_A]	= 0,
+	[AXG_ARB_TODDR_B]	= 1,
+	[AXG_ARB_TODDR_C]	= 2,
+	[AXG_ARB_FRDDR_A]	= 4,
+	[AXG_ARB_FRDDR_B]	= 5,
+	[AXG_ARB_FRDDR_C]	= 6,
+};
+
+static int meson_audio_arb_update(struct reset_controller_dev *rcdev,
+				  unsigned long id, bool assert)
+{
+	u32 val;
+	struct meson_audio_arb_data *arb =
+		container_of(rcdev, struct meson_audio_arb_data, rstc);
+
+	spin_lock(&arb->lock);
+	val = readl(arb->regs);
+
+	if (assert)
+		val &= ~BIT(arb->reset_bits[id]);
+	else
+		val |= BIT(arb->reset_bits[id]);
+
+	writel(val, arb->regs);
+	spin_unlock(&arb->lock);
+
+	return 0;
+}
+
+static int meson_audio_arb_status(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	u32 val;
+	struct meson_audio_arb_data *arb =
+		container_of(rcdev, struct meson_audio_arb_data, rstc);
+
+	val = readl(arb->regs);
+
+	return !(val & BIT(arb->reset_bits[id]));
+}
+
+static int meson_audio_arb_assert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	return meson_audio_arb_update(rcdev, id, true);
+}
+
+static int meson_audio_arb_deassert(struct reset_controller_dev *rcdev,
+				    unsigned long id)
+{
+	return meson_audio_arb_update(rcdev, id, false);
+}
+
+static const struct reset_control_ops meson_audio_arb_rstc_ops = {
+	.assert = meson_audio_arb_assert,
+	.deassert = meson_audio_arb_deassert,
+	.status = meson_audio_arb_status,
+};
+
+static const struct of_device_id meson_audio_arb_of_match[] = {
+	{ .compatible = "amlogic,meson-axg-audio-arb", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, meson_audio_arb_of_match);
+
+static int meson_audio_arb_remove(struct platform_device *pdev)
+{
+	struct meson_audio_arb_data *arb = platform_get_drvdata(pdev);
+
+	/* Disable all access */
+	spin_lock(&arb->lock);
+	writel(0, arb->regs);
+	spin_unlock(&arb->lock);
+
+	clk_disable_unprepare(arb->clk);
+
+	return 0;
+}
+
+static int meson_audio_arb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct meson_audio_arb_data *arb;
+	struct resource *res;
+	int ret;
+
+	arb = devm_kzalloc(dev, sizeof(*arb), GFP_KERNEL);
+	if (!arb)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, arb);
+
+	arb->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(arb->clk)) {
+		if (PTR_ERR(arb->clk) != -EPROBE_DEFER)
+			dev_err(dev, "failed to get clock\n");
+		return PTR_ERR(arb->clk);
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	arb->regs = devm_ioremap_resource(dev, res);
+	if (IS_ERR(arb->regs))
+		return PTR_ERR(arb->regs);
+
+	spin_lock_init(&arb->lock);
+	arb->reset_bits = axg_audio_arb_reset_bits;
+	arb->rstc.nr_resets = ARRAY_SIZE(axg_audio_arb_reset_bits);
+	arb->rstc.ops = &meson_audio_arb_rstc_ops;
+	arb->rstc.of_node = dev->of_node;
+
+	/*
+	 * Enable general :
+	 * In the initial state, all memory interfaces are disabled
+	 * and the general bit is on
+	 */
+	ret = clk_prepare_enable(arb->clk);
+	if (ret) {
+		dev_err(dev, "failed to enable arb clock\n");
+		return ret;
+	}
+	writel(BIT(ARB_GENERAL_BIT), arb->regs);
+
+	/* Register reset controller */
+	ret = devm_reset_controller_register(dev, &arb->rstc);
+	if (ret) {
+		dev_err(dev, "failed to register arb reset controller\n");
+		meson_audio_arb_remove(pdev);
+	}
+
+	return ret;
+}
+
+static struct platform_driver meson_audio_arb_pdrv = {
+	.probe = meson_audio_arb_probe,
+	.remove = meson_audio_arb_remove,
+	.driver = {
+		.name = "meson-audio-arb-reset",
+		.of_match_table = meson_audio_arb_of_match,
+	},
+};
+module_platform_driver(meson_audio_arb_pdrv);
+
+MODULE_DESCRIPTION("Amlogic A113 Audio Memory Arbiter");
+MODULE_AUTHOR("Jerome Brunet <[e-mail]>");
+MODULE_LICENSE("GPL v2");