From 50af9be8086dda5febc62f2e9f254720180a748b Mon Sep 17 00:00:00 2001
From: David Phillips <david@yeah.nah.nz>
Date: Sun, 16 May 2021 19:38:05 +1200
Subject: Add reset driver and consumer for debugging it

---
 cds9k-reset.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 cds9k-reset.c

(limited to 'cds9k-reset.c')

diff --git a/cds9k-reset.c b/cds9k-reset.c
new file mode 100644
index 0000000..d90ed7e
--- /dev/null
+++ b/cds9k-reset.c
@@ -0,0 +1,91 @@
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#define RESET_REG_0 0x0
+
+struct cds9k_reset_priv {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+	u32 base;
+};
+
+static int cds9k_reset_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct cds9k_reset_priv *priv = container_of(rcdev, struct cds9k_reset_priv, rcdev);
+
+	/* reset sequence: put 0xDEAD into reg 0 for 250 ms */
+	struct reg_sequence reset_sequence[] = {
+		{ RESET_REG_0, 0xDEAD, 250000 },
+		{ RESET_REG_0, 0x0000 },
+	};
+
+	if (id != 0)
+		return -EINVAL;
+
+	return regmap_multi_reg_write(priv->regmap, reset_sequence, ARRAY_SIZE(reset_sequence));
+}
+
+static int cds9k_reset_xlate(struct reset_controller_dev *rcdev,
+                             const struct of_phandle_args *spec)
+{
+	/* single reset */
+	return 0;
+}
+
+const struct reset_control_ops cds9k_reset_ops = {
+	.reset = cds9k_reset_reset,
+};
+
+static int cds9k_reset_probe(struct platform_device *pdev)
+{
+	struct cds9k_reset_priv *priv;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	ret = device_property_read_u32(&pdev->dev, "reg", &priv->base);
+	if (ret)
+		return -EINVAL;
+
+	if (!pdev->dev.parent)
+		return -ENODEV;
+
+	priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!priv->regmap)
+		return -ENODEV;
+
+	priv->rcdev.ops = &cds9k_reset_ops;
+	priv->rcdev.owner = pdev->dev.driver->owner;
+	priv->rcdev.of_node = pdev->dev.of_node;
+	priv->rcdev.nr_resets = 1;
+	priv->rcdev.of_reset_n_cells = 0;
+	priv->rcdev.of_xlate = cds9k_reset_xlate;
+
+	return devm_reset_controller_register(&pdev->dev, &priv->rcdev);
+}
+
+static struct of_device_id cds9k_reset_of_match[] = {
+	{ .compatible = "david,cds9k-reset" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, cds9k_reset_of_match);
+
+static struct platform_driver cds9k_reset = {
+	.driver = {
+		.name = "cds9k-reset",
+		.of_match_table = cds9k_reset_of_match,
+	},
+	.probe = cds9k_reset_probe
+};
+module_platform_driver(cds9k_reset);
+
+MODULE_AUTHOR("David Phillips <david@yeah.nah.nz>");
+MODULE_DESCRIPTION("Reset driver for the CDS9K board controller");
+MODULE_LICENSE("GPL v2");
-- 
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