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 <[email protected]> [[email protected]: add documentation, syscon name change] Signed-off-by: Suman Anna <[email protected]> --- drivers/reset/Kconfig | 11 ++ drivers/reset/Makefile | 1 + drivers/reset/reset-ti-syscon.c | 260 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 272 insertions(+) create mode 100644 drivers/reset/reset-ti-syscon.c diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index 0b2733d..60a1aed 100644 --- a/drivers/reset/Kconfig +++ b/drivers/reset/Kconfig @@ -15,5 +15,16 @@ menuconfig RESET_CONTROLLER config RESET_OXNAS bool +config TI_SYSCON_RESET + tristate "TI SYSCON Reset Driver" + depends on RESET_CONTROLLER + depends on HAS_IOMEM + select MFD_SYSCON + help + This enables the reset driver support for TI 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 f173fc3..5a9dc40 100644 --- a/drivers/reset/Makefile +++ b/drivers/reset/Makefile @@ -9,3 +9,4 @@ obj-$(CONFIG_ARCH_HISI) += hisilicon/ obj-$(CONFIG_ARCH_ZYNQ) += reset-zynq.o obj-$(CONFIG_ATH79) += reset-ath79.o obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o +obj-$(CONFIG_TI_SYSCON_RESET) += reset-ti-syscon.o diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c new file mode 100644 index 0000000..229f876 --- /dev/null +++ b/drivers/reset/reset-ti-syscon.c @@ -0,0 +1,260 @@ +/* + * TI SYSCON regmap reset driver + * + * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.com/ + * Andrew F. Davis <[email protected]> + * Suman Anna <[email protected]> + * + * 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/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> + +#include <dt-bindings/reset/ti-syscon.h> + +/** + * struct ti_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 + * @toggle: flag to indicate this reset has no readable status register + */ +struct ti_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; + bool toggle; +}; + +/** + * struct ti_syscon_reset_data - reset controller information structure + * @rcdev: reset controller entity + * @dev: reset controller device pointer + * @regmap: regmap handle containing the memory-mapped reset registers + * @controls: array of reset controls + * @nr_controls: number of controls in control array + */ +struct ti_syscon_reset_data { + struct reset_controller_dev rcdev; + struct device *dev; + struct regmap *regmap; + struct ti_syscon_reset_control *controls; + unsigned int nr_controls; +}; + +#define to_ti_syscon_reset_data(rcdev) \ + container_of(rcdev, struct ti_syscon_reset_data, rcdev) + +/** + * ti_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 ti_syscon_reset_set(struct reset_controller_dev *rcdev, + unsigned long id, bool assert) +{ + struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev); + struct ti_syscon_reset_control *control; + unsigned int mask, value; + + if (id < 0 || id >= data->nr_controls) + return -EINVAL; + + control = &data->controls[id]; + + mask = BIT(control->reset_bit); + value = (assert == control->assert_high) ? mask : 0x0; + + return regmap_update_bits(data->regmap, control->offset, mask, value); +} + +/** + * ti_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 ti_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 ti_syscon_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return ti_syscon_reset_set(rcdev, id, true); +} + +/** + * ti_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 ti_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 ti_syscon_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return ti_syscon_reset_set(rcdev, id, false); +} + +/** + * ti_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, true if reset is asserted, else a + * corresponding error value + */ +static int ti_syscon_reset_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev); + struct ti_syscon_reset_control *control; + unsigned int reset_state; + int ret; + + if (id < 0 || id >= data->nr_controls) + return -EINVAL; + + control = &data->controls[id]; + + if (control->toggle) + return -ENOSYS; /* status not supported for this reset */ + + ret = regmap_read(data->regmap, 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 ti_syscon_reset_ops = { + .assert = ti_syscon_reset_assert, + .deassert = ti_syscon_reset_deassert, + .status = ti_syscon_reset_status, +}; + +static int ti_syscon_reset_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct device_node *np = dev->of_node; + struct ti_syscon_reset_data *data; + struct regmap *regmap; + const __be32 *list; + struct ti_syscon_reset_control *controls; + int size, nr_controls, i; + u32 flags; + + if (!np) + return -ENODEV; + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + regmap = syscon_node_to_regmap(np->parent); + if (IS_ERR(regmap)) + return PTR_ERR(regmap); + + list = of_get_property(np, "ti,reset-bits", &size); + if (!list || (size / sizeof(*list)) % 5 != 0) { + dev_err(dev, "invalid DT reset description\n"); + return -EINVAL; + } + + nr_controls = (size / sizeof(*list)) / 5; + controls = devm_kzalloc(dev, nr_controls * sizeof(*controls), GFP_KERNEL); + if (!controls) + return -ENOMEM; + + for (i = 0; i < nr_controls; i++) { + controls[i].offset = be32_to_cpup(list++); + controls[i].reset_bit = be32_to_cpup(list++); + controls[i].status_offset = be32_to_cpup(list++); + controls[i].status_reset_bit = be32_to_cpup(list++); + + flags = be32_to_cpup(list++); + controls[i].assert_high = !!(flags & RESET_SET); + controls[i].status_assert_high = !!(flags & RESET_SET); + controls[i].toggle = !!(flags & RESET_TRIGGER); + } + + data->rcdev.ops = &ti_syscon_reset_ops; + data->rcdev.owner = THIS_MODULE; + data->rcdev.of_node = np; + data->rcdev.nr_resets = nr_controls; + data->dev = dev; + data->regmap = regmap; + data->controls = controls; + data->nr_controls = nr_controls; + + platform_set_drvdata(pdev, data); + + return reset_controller_register(&data->rcdev); +} + +static int ti_syscon_reset_remove(struct platform_device *pdev) +{ + struct ti_syscon_reset_data *data = platform_get_drvdata(pdev); + + reset_controller_unregister(&data->rcdev); + + return 0; +} + +static const struct of_device_id ti_syscon_reset_of_match[] = { + { .compatible = "syscon-reset", }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match); + +static struct platform_driver ti_syscon_reset_driver = { + .probe = ti_syscon_reset_probe, + .remove = ti_syscon_reset_remove, + .driver = { + .name = "ti-syscon-reset", + .of_match_table = ti_syscon_reset_of_match, + }, +}; +module_platform_driver(ti_syscon_reset_driver); + +MODULE_AUTHOR("Andrew F. Davis <[email protected]>"); +MODULE_AUTHOR("Suman Anna <[email protected]>"); +MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver"); +MODULE_LICENSE("GPL v2"); -- 2.9.0
