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 <sean...@gmail.com>
---
Changes for v3:
- New
.../reset/syscon-reset.txt | 36 +++++++++
drivers/reset/Kconfig | 6 +-
drivers/reset/Makefile | 1 +
drivers/reset/reset-syscon.c | 79 +++++++++++++++++++
4 files changed, 121 insertions(+), 1 deletion(-)
create mode 100644 doc/device-tree-bindings/reset/syscon-reset.txt
create mode 100644 drivers/reset/reset-syscon.c
diff --git a/doc/device-tree-bindings/reset/syscon-reset.txt
b/doc/device-tree-bindings/reset/syscon-reset.txt
new file mode 100644
index 0000000000..47c1226567
--- /dev/null
+++ b/doc/device-tree-bindings/reset/syscon-reset.txt
@@ -0,0 +1,36 @@
+Generic SYSCON mapped register reset driver
+
+This is a generic reset driver using syscon to map the reset register.
+The reset is generally performed with a write to the reset register
+defined by the register map pointed by syscon reference plus the offset and
+shifted by the reset specifier/
+
+To assert a reset on some device, the equivalent of the following operation is
+performed, where reset_id is the reset specifier from the device's resets
+property.
+
+ if (BIT(reset_id) & mask)
+ regmap[offset][reset_id] = assert-high;
+
+Required properties:
+- compatible: should contain "syscon-reset"
+- #reset-cells: must be 1
+- regmap: this is phandle to the register map node
+- offset: offset in the register map for the reboot register (in bytes)
+
+Optional properties:
+- mask: accept only the reset specifiers defined by the mask (32 bit)
+- assert-high: Bit to write when asserting a reset. Defaults to 1.
+
+Default will be little endian mode, 32 bit access only.
+
+Example:
+
+ reset-controller {
+ compatible = "syscon-reset";
+ #reset-cells = <1>;
+ regmap = <&sysctl>;
+ offset = <0x20>;
+ mask = <0x27FFFFFF>;
+ assert-high = <0>;
+ };
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 75ccd65799..759d659c82 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -147,5 +147,9 @@ config RESET_IMX7
default y
help
Support for reset controller on i.MX7/8 SoCs.
-
+config RESET_SYSCON
+ bool "Enable generic syscon reset driver support"
+ depends on DM_RESET
+ help
+ Support generic syscon mapped register reset devices.
endmenu
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 0a044d5d8c..433f1eca54 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -23,3 +23,4 @@ obj-$(CONFIG_RESET_MTMIPS) += reset-mtmips.o
obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
obj-$(CONFIG_RESET_HISILICON) += reset-hisilicon.o
obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
+obj-$(CONFIG_RESET_SYSCON) += reset-syscon.o
diff --git a/drivers/reset/reset-syscon.c b/drivers/reset/reset-syscon.c
new file mode 100644
index 0000000000..db58b7705a
--- /dev/null
+++ b/drivers/reset/reset-syscon.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Sean Anderson
+ */
+
+#include <dm.h>
+#include <linux/bitops.h>
+#include <regmap.h>
+#include <reset.h>
+#include <reset-uclass.h>
+#include <syscon.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);
+}
+
+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);
+}
+
+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,
+};
--
2.25.0
