reset: Add generic reset driver
This patch adds a generic reset driver. It is designed to be useful when
one has a register in a regmap which contains bits that reset other
devices. I thought this seemed like a very generic use, so here is a
generic driver. The overall structure has been modeled on the syscon-reboot
driver.
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/reset/reset-syscon.c b/drivers/reset/reset-syscon.c
new file mode 100644
index 0000000..8520227
--- /dev/null
+++ b/drivers/reset/reset-syscon.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Sean Anderson
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <regmap.h>
+#include <reset.h>
+#include <reset-uclass.h>
+#include <syscon.h>
+#include <linux/bitops.h>
+#include <linux/err.h>
+
+struct syscon_reset_priv {
+ struct regmap *regmap;
+ uint offset;
+ uint mask;
+ bool assert_high;
+};
+
+static int syscon_reset_request(struct reset_ctl *rst)
+{
+ struct syscon_reset_priv *priv = dev_get_priv(rst->dev);
+
+ if (BIT(rst->id) & priv->mask)
+ return 0;
+ else
+ return -EINVAL;
+}
+
+static int syscon_reset_assert(struct reset_ctl *rst)
+{
+ struct syscon_reset_priv *priv = dev_get_priv(rst->dev);
+
+ return regmap_update_bits(priv->regmap, priv->offset, BIT(rst->id),
+ priv->assert_high ? BIT(rst->id) : 0);
+}
+
+static int syscon_reset_deassert(struct reset_ctl *rst)
+{
+ struct syscon_reset_priv *priv = dev_get_priv(rst->dev);
+
+ return regmap_update_bits(priv->regmap, priv->offset, BIT(rst->id),
+ priv->assert_high ? 0 : BIT(rst->id));
+}
+
+static const struct reset_ops syscon_reset_ops = {
+ .request = syscon_reset_request,
+ .rst_assert = syscon_reset_assert,
+ .rst_deassert = syscon_reset_deassert,
+};
+
+int syscon_reset_probe(struct udevice *dev)
+{
+ struct syscon_reset_priv *priv = dev_get_priv(dev);
+
+ priv->regmap = syscon_regmap_lookup_by_phandle(dev, "regmap");
+ if (IS_ERR(priv->regmap))
+ return -ENODEV;
+
+ priv->offset = dev_read_u32_default(dev, "offset", 0);
+ priv->mask = dev_read_u32_default(dev, "mask", 0);
+ priv->assert_high = dev_read_u32_default(dev, "assert-high", true);
+
+ return 0;
+}
+
+static const struct udevice_id syscon_reset_ids[] = {
+ { .compatible = "syscon-reset" },
+ { },
+};
+
+U_BOOT_DRIVER(syscon_reset) = {
+ .name = "syscon_reset",
+ .id = UCLASS_RESET,
+ .of_match = syscon_reset_ids,
+ .probe = syscon_reset_probe,
+ .priv_auto_alloc_size = sizeof(struct syscon_reset_priv),
+ .ops = &syscon_reset_ops,
+};