This patch adds support for the reset controller found on the Amlogic
MesonX SoCs. For several devices in the AO (Always-On) power domain, it
is possible to reset them by programming a specific bit in a register.
Signed-off-by: Carlo Caione <carlo@xxxxxxxxxx>
---
drivers/reset/Makefile | 1 +
drivers/reset/reset-meson.c | 142 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 143 insertions(+)
create mode 100644 drivers/reset/reset-meson.c
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 60fed3d..74f2372 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -1,4 +1,5 @@
obj-$(CONFIG_RESET_CONTROLLER) += core.o
obj-$(CONFIG_ARCH_SOCFPGA) += reset-socfpga.o
obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
+obj-$(CONFIG_ARCH_MESON) += reset-meson.o
obj-$(CONFIG_ARCH_STI) += sti/
diff --git a/drivers/reset/reset-meson.c b/drivers/reset/reset-meson.c
new file mode 100644
index 0000000..59b58e4
--- /dev/null
+++ b/drivers/reset/reset-meson.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright 2014 Carlo Caione <carlo@xxxxxxxxxx>
+ *
+ * based on
+ * Steffen Trumtrar Reset Controller driver
+ *
+ * Copyright 2014 Steffen Trumtrar
+ *
+ * Steffen Trumtrar <s.trumtrar@xxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#define MESON_RST_OFFSET 0x00
+
+struct meson_reset_data {
+ spinlock_t lock;
+ void __iomem *membase;
+ struct reset_controller_dev rcdev;
+};
+
+static int meson_reset_assert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct meson_reset_data *data = container_of(rcdev,
+ struct meson_reset_data,
+ rcdev);
+ unsigned long flags;
+ u32 reg;
+
+ spin_lock_irqsave(&data->lock, flags);
+
+ reg = readl(data->membase + MESON_RST_OFFSET);
+ writel(reg | BIT(id), data->membase + MESON_RST_OFFSET);
+
+ spin_unlock_irqrestore(&data->lock, flags);
+
+ return 0;
+}
+
+static int meson_reset_deassert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct meson_reset_data *data = container_of(rcdev,
+ struct meson_reset_data,
+ rcdev);
+
+ unsigned long flags;
+ u32 reg;
+
+ spin_lock_irqsave(&data->lock, flags);
+
+ reg = readl(data->membase + MESON_RST_OFFSET);
+ writel(reg & ~BIT(id), data->membase + MESON_RST_OFFSET);
+
+ spin_unlock_irqrestore(&data->lock, flags);
+
+ return 0;
+}
+
+static int meson_reset_dev(struct reset_controller_dev *rcdev, unsigned long id)
+{
+ int err;
+
+ err = meson_reset_assert(rcdev, id);
+ if (err)
+ return err;
+
+ return meson_reset_deassert(rcdev, id);
+}
+
+static struct reset_control_ops meson_reset_ops = {
+ .assert = meson_reset_assert,
+ .deassert = meson_reset_deassert,
+ .reset = meson_reset_dev,
+};
+
+static int meson_reset_probe(struct platform_device *pdev)
+{
+ struct meson_reset_data *data;
+ struct resource *res;
+
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ data->membase = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(data->membase))
+ return PTR_ERR(data->membase);
+
+ spin_lock_init(&data->lock);
+
+ platform_set_drvdata(pdev, data);
+
+ data->rcdev.owner = THIS_MODULE;
+ data->rcdev.nr_resets = BITS_PER_LONG;
+ data->rcdev.ops = &meson_reset_ops;
+ data->rcdev.of_node = pdev->dev.of_node;
+
+ return reset_controller_register(&data->rcdev);
+}
+
+static int meson_reset_remove(struct platform_device *pdev)
+{
+ struct meson_reset_data *data = platform_get_drvdata(pdev);
+
+ reset_controller_unregister(&data->rcdev);
+
+ return 0;
+}
+
+static const struct of_device_id meson_reset_dt_ids[] = {
+ { .compatible = "amlogic,meson6-rst-mgr-ao", },
+ { /* sentinel */ },
+};
+
+static struct platform_driver meson_reset_driver = {
+ .probe = meson_reset_probe,
+ .remove = meson_reset_remove,
+ .driver = {
+ .name = "meson-reset",
+ .of_match_table = meson_reset_dt_ids,
+ },
+};
+module_platform_driver(meson_reset_driver);
+
+MODULE_AUTHOR("Carlo Caione <carlo@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Meson Reset Controller Driver");
+MODULE_LICENSE("GPL");
--
1.9.1
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