This patch adds support for the reset controller found on the Amlogic MesonX SoCs. For several devices in the AO (Always-On) power domain, it is possible to reset them by programming a specific bit in a register.
Signed-off-by: Carlo Caione <[email protected]> --- drivers/reset/Makefile | 1 + drivers/reset/reset-meson.c | 142 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 143 insertions(+) create mode 100644 drivers/reset/reset-meson.c diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index 60fed3d..74f2372 100644 --- a/drivers/reset/Makefile +++ b/drivers/reset/Makefile @@ -1,4 +1,5 @@ obj-$(CONFIG_RESET_CONTROLLER) += core.o obj-$(CONFIG_ARCH_SOCFPGA) += reset-socfpga.o obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o +obj-$(CONFIG_ARCH_MESON) += reset-meson.o obj-$(CONFIG_ARCH_STI) += sti/ diff --git a/drivers/reset/reset-meson.c b/drivers/reset/reset-meson.c new file mode 100644 index 0000000..59b58e4 --- /dev/null +++ b/drivers/reset/reset-meson.c @@ -0,0 +1,142 @@ +/* + * Copyright 2014 Carlo Caione <[email protected]> + * + * based on + * Steffen Trumtrar Reset Controller driver + * + * Copyright 2014 Steffen Trumtrar + * + * Steffen Trumtrar <[email protected]> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ + +#include <linux/err.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/reset-controller.h> +#include <linux/spinlock.h> +#include <linux/types.h> + +#define MESON_RST_OFFSET 0x00 + +struct meson_reset_data { + spinlock_t lock; + void __iomem *membase; + struct reset_controller_dev rcdev; +}; + +static int meson_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct meson_reset_data *data = container_of(rcdev, + struct meson_reset_data, + rcdev); + unsigned long flags; + u32 reg; + + spin_lock_irqsave(&data->lock, flags); + + reg = readl(data->membase + MESON_RST_OFFSET); + writel(reg | BIT(id), data->membase + MESON_RST_OFFSET); + + spin_unlock_irqrestore(&data->lock, flags); + + return 0; +} + +static int meson_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct meson_reset_data *data = container_of(rcdev, + struct meson_reset_data, + rcdev); + + unsigned long flags; + u32 reg; + + spin_lock_irqsave(&data->lock, flags); + + reg = readl(data->membase + MESON_RST_OFFSET); + writel(reg & ~BIT(id), data->membase + MESON_RST_OFFSET); + + spin_unlock_irqrestore(&data->lock, flags); + + return 0; +} + +static int meson_reset_dev(struct reset_controller_dev *rcdev, unsigned long id) +{ + int err; + + err = meson_reset_assert(rcdev, id); + if (err) + return err; + + return meson_reset_deassert(rcdev, id); +} + +static struct reset_control_ops meson_reset_ops = { + .assert = meson_reset_assert, + .deassert = meson_reset_deassert, + .reset = meson_reset_dev, +}; + +static int meson_reset_probe(struct platform_device *pdev) +{ + struct meson_reset_data *data; + struct resource *res; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + data->membase = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(data->membase)) + return PTR_ERR(data->membase); + + spin_lock_init(&data->lock); + + platform_set_drvdata(pdev, data); + + data->rcdev.owner = THIS_MODULE; + data->rcdev.nr_resets = BITS_PER_LONG; + data->rcdev.ops = &meson_reset_ops; + data->rcdev.of_node = pdev->dev.of_node; + + return reset_controller_register(&data->rcdev); +} + +static int meson_reset_remove(struct platform_device *pdev) +{ + struct meson_reset_data *data = platform_get_drvdata(pdev); + + reset_controller_unregister(&data->rcdev); + + return 0; +} + +static const struct of_device_id meson_reset_dt_ids[] = { + { .compatible = "amlogic,meson6-rst-mgr-ao", }, + { /* sentinel */ }, +}; + +static struct platform_driver meson_reset_driver = { + .probe = meson_reset_probe, + .remove = meson_reset_remove, + .driver = { + .name = "meson-reset", + .of_match_table = meson_reset_dt_ids, + }, +}; +module_platform_driver(meson_reset_driver); + +MODULE_AUTHOR("Carlo Caione <[email protected]>"); +MODULE_DESCRIPTION("Meson Reset Controller Driver"); +MODULE_LICENSE("GPL"); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
