Add a reset-controller driver for performing reset management of various devices present on the SoC, with the reset registers shared between devices in a common register memory space. This driver uses the syscon/regmap frameworks to actually implement the various reset functionalities needed by the reset consumer devices. Signed-off-by: Andrew F. Davis <afd@xxxxxx> [s-anna@xxxxxx: add documentation, syscon name change] Signed-off-by: Suman Anna <s-anna@xxxxxx> --- drivers/reset/Kconfig | 10 ++ drivers/reset/Makefile | 1 + drivers/reset/reset-syscon.c | 259 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 270 insertions(+) create mode 100644 drivers/reset/reset-syscon.c diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index df37212..5f26755 100644 --- a/drivers/reset/Kconfig +++ b/drivers/reset/Kconfig @@ -12,5 +12,15 @@ menuconfig RESET_CONTROLLER If unsure, say no. +config SYSCON_RESET + tristate "SYSCON Reset Driver" + depends on RESET_CONTROLLER + select MFD_SYSCON + help + This enables the reset driver support for devices with memory-mapped + reset registers as part of a syscon device node. If you wish to use + the reset framework for such memory-mapped devices, say Y here. + Otherwise, say N. + source "drivers/reset/sti/Kconfig" source "drivers/reset/hisilicon/Kconfig" diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index 4d7178e..6b3f6e3 100644 --- a/drivers/reset/Makefile +++ b/drivers/reset/Makefile @@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_STI) += sti/ obj-$(CONFIG_ARCH_HISI) += hisilicon/ obj-$(CONFIG_ARCH_ZYNQ) += reset-zynq.o obj-$(CONFIG_ATH79) += reset-ath79.o +obj-$(CONFIG_SYSCON_RESET) += reset-syscon.o diff --git a/drivers/reset/reset-syscon.c b/drivers/reset/reset-syscon.c new file mode 100644 index 0000000..48c8c30 --- /dev/null +++ b/drivers/reset/reset-syscon.c @@ -0,0 +1,259 @@ +/* + * SYSCON regmap reset driver + * + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/ + * Andrew F. Davis <afd@xxxxxx> + * Suman Anna <afd@xxxxxx> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/idr.h> +#include <linux/mfd/syscon.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> +#include <linux/reset-controller.h> + +/** + * struct syscon_reset_control - reset control structure + * @offset: reset control register offset from syscon base + * @reset_bit: reset bit in the reset control register + * @assert_high: flag to indicate if setting the bit high asserts the reset + * @status_offset: reset status register offset from syscon base + * @status_reset_bit: reset status bit in the reset status register + * @status_assert_high: flag to indicate if a set bit represents asserted state + */ +struct syscon_reset_control { + unsigned int offset; + unsigned int reset_bit; + bool assert_high; + unsigned int status_offset; + unsigned int status_reset_bit; + bool status_assert_high; +}; + +/** + * struct syscon_reset_data - reset controller information structure + * @rcdev: reset controller entity + * @dev: reset controller device pointer + * @memory: regmap handle containing the memory-mapped reset registers + * @idr: idr structure for mapping ids to reset control structures + */ +struct syscon_reset_data { + struct reset_controller_dev rcdev; + struct device *dev; + struct regmap *memory; + struct idr idr; +}; + +#define to_syscon_reset_data(rcdev) \ + container_of(rcdev, struct syscon_reset_data, rcdev) + +/** + * syscon_reset_set() - program a device's reset + * @rcdev: reset controller entity + * @id: ID of the reset to toggle + * @assert: boolean flag to indicate assert or deassert + * + * This is a common internal function used to assert or deassert a device's + * reset using the regmap API. The device's reset is asserted if the @assert + * argument is true, or deasserted if the @assert argument is false. + * + * Return: 0 for successful request, else a corresponding error value + */ +static int syscon_reset_set(struct reset_controller_dev *rcdev, + unsigned long id, bool assert) +{ + struct syscon_reset_data *data = to_syscon_reset_data(rcdev); + struct syscon_reset_control *control; + unsigned int mask, value; + + control = idr_find(&data->idr, id); + if (!control) + return -EINVAL; + + mask = BIT(control->reset_bit); + value = (assert == control->assert_high) ? mask : 0x0; + + return regmap_update_bits(data->memory, control->offset, mask, value); +} + +/** + * syscon_reset_assert() - assert device reset + * @rcdev: reset controller entity + * @id: ID of the reset to be asserted + * + * This function implements the reset driver op to assert a device's reset. + * This invokes the function syscon_reset_set() with the corresponding + * parameters as passed in, but with the @assert argument set to true for + * asserting the reset. + * + * Return: 0 for successful request, else a corresponding error value + */ +static int syscon_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return syscon_reset_set(rcdev, id, true); +} + +/** + * syscon_reset_deassert() - deassert device reset + * @rcdev: reset controller entity + * @id: ID of reset to be deasserted + * + * This function implements the reset driver op to deassert a device's reset. + * This invokes the function syscon_reset_set() with the corresponding + * parameters as passed in, but with the @assert argument set to false for + * deasserting the reset. + * + * Return: 0 for successful request, else a corresponding error value + */ +static int syscon_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return syscon_reset_set(rcdev, id, false); +} + +/** + * syscon_reset_status() - check device reset status + * @rcdev: reset controller entity + * @id: ID of the reset for which the status is being requested + * + * This function implements the reset driver op to return the status of a + * device's reset. + * + * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted + */ +static int syscon_reset_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct syscon_reset_data *data = to_syscon_reset_data(rcdev); + struct syscon_reset_control *control; + unsigned int reset_state; + int ret; + + control = idr_find(&data->idr, id); + if (!control) + return -EINVAL; + + ret = regmap_read(data->memory, control->status_offset, &reset_state); + if (ret) + return ret; + + return (reset_state & BIT(control->status_reset_bit)) == + control->status_assert_high; +} + +static struct reset_control_ops syscon_reset_ops = { + .assert = syscon_reset_assert, + .deassert = syscon_reset_deassert, + .status = syscon_reset_status, +}; + +/** + * syscon_reset_of_xlate() - translate a set of OF arguments to a reset ID + * @rcdev: reset controller entity + * @reset_spec: OF reset argument specifier + * + * This function performs the translation of the reset argument specifier + * values defined in a reset consumer device node. The function allocates a + * reset control structure for that device reset, that will be used by the + * driver for performing any reset functions on that reset. An idr structure + * is allocated and used to map to the reset control structure. This idr is + * used by the driver to do reset lookups. + * + * Return: 0 for successful request, else a corresponding error value + */ +static int syscon_reset_of_xlate(struct reset_controller_dev *rcdev, + const struct of_phandle_args *reset_spec) +{ + struct syscon_reset_data *data = to_syscon_reset_data(rcdev); + struct syscon_reset_control *control; + + if (WARN_ON(reset_spec->args_count != 6)) + return -EINVAL; + + control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL); + if (!control) + return -ENOMEM; + + control->offset = reset_spec->args[0]; + control->reset_bit = reset_spec->args[1]; + control->assert_high = reset_spec->args[2] == 1; + control->status_offset = reset_spec->args[3]; + control->status_reset_bit = reset_spec->args[4]; + control->status_assert_high = reset_spec->args[5] == 1; + + return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL); +} + +static int syscon_reset_probe(struct platform_device *pdev) +{ + struct syscon_reset_data *data; + struct device_node *np = pdev->dev.of_node; + struct regmap *memory; + + if (!np) + return -ENODEV; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + memory = syscon_regmap_lookup_by_phandle(np, "syscon"); + if (IS_ERR(memory)) + return PTR_ERR(memory); + + data->rcdev.ops = &syscon_reset_ops; + data->rcdev.owner = THIS_MODULE; + data->rcdev.of_node = np; + data->rcdev.of_xlate = syscon_reset_of_xlate; + data->dev = &pdev->dev; + data->memory = memory; + idr_init(&data->idr); + + platform_set_drvdata(pdev, data); + + return reset_controller_register(&data->rcdev); +} + +static int syscon_reset_remove(struct platform_device *pdev) +{ + struct syscon_reset_data *data = platform_get_drvdata(pdev); + + reset_controller_unregister(&data->rcdev); + + idr_destroy(&data->idr); + + return 0; +} + +static const struct of_device_id syscon_reset_of_match_table[] = { + { .compatible = "syscon-reset", }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, syscon_reset_of_match_table); + +static struct platform_driver syscon_reset_driver = { + .probe = syscon_reset_probe, + .remove = syscon_reset_remove, + .driver = { + .name = "syscon-reset", + .of_match_table = syscon_reset_of_match_table, + }, +}; +module_platform_driver(syscon_reset_driver); + +MODULE_AUTHOR("Andrew F. Davis <afd@xxxxxx>"); +MODULE_AUTHOR("Suman Anna <s-anna@xxxxxx>"); +MODULE_DESCRIPTION("SYSCON Regmap Reset Driver"); +MODULE_LICENSE("GPL v2"); -- 2.7.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
