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Subject[PATCH 2/2] reset: Add basic single-register reset driver
Date
This driver is a basic single-register reset controller driver that
supports clearing a single bit in a register.

Signed-off-by: Joel Stanley <joel@jms.id.au>
---
drivers/reset/Kconfig | 6 +++
drivers/reset/Makefile | 1 +
drivers/reset/reset-basic.c | 109 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 116 insertions(+)
create mode 100644 drivers/reset/reset-basic.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index d21c07ccc94e..980cda887dfe 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -28,6 +28,12 @@ config RESET_ATH79
This enables the ATH79 reset controller driver that supports the
AR71xx SoC reset controller.

+config RESET_BASIC
+ bool "Basic Reset Driver"
+ help
+ This enables a basic single-register reset controller driver that
+ supports clearing a single bit in a register.
+
config RESET_BERLIN
bool "Berlin Reset Driver" if COMPILE_TEST
default ARCH_BERLIN
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 02a74db94339..e8e8869e098d 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_ARCH_STI) += sti/
obj-$(CONFIG_ARCH_TEGRA) += tegra/
obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
+obj-$(CONFIG_RESET_BASIC) += reset-basic.o
obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
diff --git a/drivers/reset/reset-basic.c b/drivers/reset/reset-basic.c
new file mode 100644
index 000000000000..62a676de9f62
--- /dev/null
+++ b/drivers/reset/reset-basic.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright 2017 IBM Corperation
+ *
+ * Joel Stanley <joel@jms.id.au>
+ *
+ * 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/delay.h>
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+#include <linux/reset-controller.h>
+
+#define to_basic_reset_priv(p) \
+ container_of((p), struct basic_reset_priv, rcdev)
+
+struct basic_reset_priv {
+ struct regmap *regmap;
+ struct reset_controller_dev rcdev;
+ u32 reg;
+};
+
+static int basic_reset_assert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct basic_reset_priv *priv = to_basic_reset_priv(rcdev);
+ u32 mask = BIT(id);
+
+ regmap_update_bits(priv->regmap, priv->reg, mask, mask);
+
+ return 0;
+}
+
+static int basic_reset_deassert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct basic_reset_priv *priv = to_basic_reset_priv(rcdev);
+ u32 mask = BIT(id);
+
+ regmap_update_bits(priv->regmap, priv->reg, mask, 0);
+
+ return 0;
+}
+
+static int basic_reset_status(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct basic_reset_priv *priv = to_basic_reset_priv(rcdev);
+ u32 mask = BIT(id);
+ u32 val;
+
+ regmap_read(priv->regmap, priv->reg, &val);
+
+ return !!(val & mask);
+}
+
+static const struct reset_control_ops basic_reset_ops = {
+ .assert = basic_reset_assert,
+ .deassert = basic_reset_deassert,
+ .status = basic_reset_status,
+};
+
+static int basic_reset_probe(struct platform_device *pdev)
+{
+ struct device_node *parent_np = of_get_parent(pdev->dev.of_node);
+ struct basic_reset_priv *priv;
+ int ret;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->regmap = syscon_node_to_regmap(parent_np);
+ of_node_put(parent_np);
+ if (IS_ERR(priv->regmap))
+ return PTR_ERR(priv->regmap);
+
+ ret = of_property_read_u32(pdev->dev.of_node, "reg", &priv->reg);
+ if (ret)
+ return ret;
+
+ priv->rcdev.owner = THIS_MODULE;
+ priv->rcdev.ops = &basic_reset_ops;
+ priv->rcdev.of_node = pdev->dev.of_node;
+ priv->rcdev.nr_resets = 32;
+
+ return reset_controller_register(&priv->rcdev);
+}
+
+static const struct of_device_id basic_reset_dt_match[] = {
+ { .compatible = "reset-basic" },
+ { },
+};
+
+static struct platform_driver basic_reset_driver = {
+ .probe = basic_reset_probe,
+ .driver = {
+ .name = "basic-reset",
+ .of_match_table = basic_reset_dt_match,
+ },
+};
+builtin_platform_driver(basic_reset_driver);
--
2.11.0
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