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 --- 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, +};