diff options
Diffstat (limited to 'drivers/reset/reset-simple.c')
| -rw-r--r-- | drivers/reset/reset-simple.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/drivers/reset/reset-simple.c b/drivers/reset/reset-simple.c new file mode 100644 index 000000000..a91107fc9 --- /dev/null +++ b/drivers/reset/reset-simple.c @@ -0,0 +1,189 @@ +/* + * Simple Reset Controller Driver + * + * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de> + * + * Based on Allwinner SoCs Reset Controller driver + * + * Copyright 2013 Maxime Ripard + * + * Maxime Ripard <maxime.ripard@free-electrons.com> + * + * 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/device.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/of.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/reset-controller.h> +#include <linux/spinlock.h> + +#include "reset-simple.h" + +static inline struct reset_simple_data * +to_reset_simple_data(struct reset_controller_dev *rcdev) +{ + return container_of(rcdev, struct reset_simple_data, rcdev); +} + +static int reset_simple_update(struct reset_controller_dev *rcdev, + unsigned long id, bool assert) +{ + struct reset_simple_data *data = to_reset_simple_data(rcdev); + int reg_width = sizeof(u32); + int bank = id / (reg_width * BITS_PER_BYTE); + int offset = id % (reg_width * BITS_PER_BYTE); + unsigned long flags; + u32 reg; + + spin_lock_irqsave(&data->lock, flags); + + reg = readl(data->membase + (bank * reg_width)); + if (assert ^ data->active_low) + reg |= BIT(offset); + else + reg &= ~BIT(offset); + writel(reg, data->membase + (bank * reg_width)); + + spin_unlock_irqrestore(&data->lock, flags); + + return 0; +} + +static int reset_simple_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return reset_simple_update(rcdev, id, true); +} + +static int reset_simple_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return reset_simple_update(rcdev, id, false); +} + +static int reset_simple_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct reset_simple_data *data = to_reset_simple_data(rcdev); + int reg_width = sizeof(u32); + int bank = id / (reg_width * BITS_PER_BYTE); + int offset = id % (reg_width * BITS_PER_BYTE); + u32 reg; + + reg = readl(data->membase + (bank * reg_width)); + + return !(reg & BIT(offset)) ^ !data->status_active_low; +} + +const struct reset_control_ops reset_simple_ops = { + .assert = reset_simple_assert, + .deassert = reset_simple_deassert, + .status = reset_simple_status, +}; +EXPORT_SYMBOL_GPL(reset_simple_ops); + +/** + * struct reset_simple_devdata - simple reset controller properties + * @reg_offset: offset between base address and first reset register. + * @nr_resets: number of resets. If not set, default to resource size in bits. + * @active_low: if true, bits are cleared to assert the reset. Otherwise, bits + * are set to assert the reset. + * @status_active_low: if true, bits read back as cleared while the reset is + * asserted. Otherwise, bits read back as set while the + * reset is asserted. + */ +struct reset_simple_devdata { + u32 reg_offset; + u32 nr_resets; + bool active_low; + bool status_active_low; +}; + +#define SOCFPGA_NR_BANKS 8 + +static const struct reset_simple_devdata reset_simple_socfpga = { + .reg_offset = 0x10, + .nr_resets = SOCFPGA_NR_BANKS * 32, + .status_active_low = true, +}; + +static const struct reset_simple_devdata reset_simple_active_low = { + .active_low = true, + .status_active_low = true, +}; + +static const struct of_device_id reset_simple_dt_ids[] = { + { .compatible = "altr,rst-mgr", .data = &reset_simple_socfpga }, + { .compatible = "st,stm32-rcc", }, + { .compatible = "allwinner,sun6i-a31-clock-reset", + .data = &reset_simple_active_low }, + { .compatible = "zte,zx296718-reset", + .data = &reset_simple_active_low }, + { .compatible = "aspeed,ast2400-lpc-reset" }, + { .compatible = "aspeed,ast2500-lpc-reset" }, + { /* sentinel */ }, +}; + +static int reset_simple_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + const struct reset_simple_devdata *devdata; + struct reset_simple_data *data; + void __iomem *membase; + struct resource *res; + u32 reg_offset = 0; + + devdata = of_device_get_match_data(dev); + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + membase = devm_ioremap_resource(dev, res); + if (IS_ERR(membase)) + return PTR_ERR(membase); + + spin_lock_init(&data->lock); + data->membase = membase; + data->rcdev.owner = THIS_MODULE; + data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE; + data->rcdev.ops = &reset_simple_ops; + data->rcdev.of_node = dev->of_node; + + if (devdata) { + reg_offset = devdata->reg_offset; + if (devdata->nr_resets) + data->rcdev.nr_resets = devdata->nr_resets; + data->active_low = devdata->active_low; + data->status_active_low = devdata->status_active_low; + } + + if (of_device_is_compatible(dev->of_node, "altr,rst-mgr") && + of_property_read_u32(dev->of_node, "altr,modrst-offset", + ®_offset)) { + dev_warn(dev, + "missing altr,modrst-offset property, assuming 0x%x!\n", + reg_offset); + } + + data->membase += reg_offset; + + return devm_reset_controller_register(dev, &data->rcdev); +} + +static struct platform_driver reset_simple_driver = { + .probe = reset_simple_probe, + .driver = { + .name = "simple-reset", + .of_match_table = reset_simple_dt_ids, + }, +}; +builtin_platform_driver(reset_simple_driver); |