diff options
Diffstat (limited to 'drivers/reset/reset-starfive-jh7100.c')
| -rw-r--r-- | drivers/reset/reset-starfive-jh7100.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/drivers/reset/reset-starfive-jh7100.c b/drivers/reset/reset-starfive-jh7100.c new file mode 100644 index 000000000000..fc44b2fb3e03 --- /dev/null +++ b/drivers/reset/reset-starfive-jh7100.c @@ -0,0 +1,173 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Reset driver for the StarFive JH7100 SoC + * + * Copyright (C) 2021 Emil Renner Berthing <kernel@esmil.dk> + */ + +#include <linux/bitmap.h> +#include <linux/io.h> +#include <linux/io-64-nonatomic-lo-hi.h> +#include <linux/iopoll.h> +#include <linux/mod_devicetable.h> +#include <linux/platform_device.h> +#include <linux/reset-controller.h> +#include <linux/spinlock.h> + +#include <dt-bindings/reset/starfive-jh7100.h> + +/* register offsets */ +#define JH7100_RESET_ASSERT0 0x00 +#define JH7100_RESET_ASSERT1 0x04 +#define JH7100_RESET_ASSERT2 0x08 +#define JH7100_RESET_ASSERT3 0x0c +#define JH7100_RESET_STATUS0 0x10 +#define JH7100_RESET_STATUS1 0x14 +#define JH7100_RESET_STATUS2 0x18 +#define JH7100_RESET_STATUS3 0x1c + +/* + * Writing a 1 to the n'th bit of the m'th ASSERT register asserts + * line 32m + n, and writing a 0 deasserts the same line. + * Most reset lines have their status inverted so a 0 bit in the STATUS + * register means the line is asserted and a 1 means it's deasserted. A few + * lines don't though, so store the expected value of the status registers when + * all lines are asserted. + */ +static const u64 jh7100_reset_asserted[2] = { + /* STATUS0 */ + BIT_ULL_MASK(JH7100_RST_U74) | + BIT_ULL_MASK(JH7100_RST_VP6_DRESET) | + BIT_ULL_MASK(JH7100_RST_VP6_BRESET) | + /* STATUS1 */ + BIT_ULL_MASK(JH7100_RST_HIFI4_DRESET) | + BIT_ULL_MASK(JH7100_RST_HIFI4_BRESET), + /* STATUS2 */ + BIT_ULL_MASK(JH7100_RST_E24) | + /* STATUS3 */ + 0, +}; + +struct jh7100_reset { + struct reset_controller_dev rcdev; + /* protect registers against concurrent read-modify-write */ + spinlock_t lock; + void __iomem *base; +}; + +static inline struct jh7100_reset * +jh7100_reset_from(struct reset_controller_dev *rcdev) +{ + return container_of(rcdev, struct jh7100_reset, rcdev); +} + +static int jh7100_reset_update(struct reset_controller_dev *rcdev, + unsigned long id, bool assert) +{ + struct jh7100_reset *data = jh7100_reset_from(rcdev); + unsigned long offset = BIT_ULL_WORD(id); + u64 mask = BIT_ULL_MASK(id); + void __iomem *reg_assert = data->base + JH7100_RESET_ASSERT0 + offset * sizeof(u64); + void __iomem *reg_status = data->base + JH7100_RESET_STATUS0 + offset * sizeof(u64); + u64 done = jh7100_reset_asserted[offset] & mask; + u64 value; + unsigned long flags; + int ret; + + if (!assert) + done ^= mask; + + spin_lock_irqsave(&data->lock, flags); + + value = readq(reg_assert); + if (assert) + value |= mask; + else + value &= ~mask; + writeq(value, reg_assert); + + /* if the associated clock is gated, deasserting might otherwise hang forever */ + ret = readq_poll_timeout_atomic(reg_status, value, (value & mask) == done, 0, 1000); + + spin_unlock_irqrestore(&data->lock, flags); + return ret; +} + +static int jh7100_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return jh7100_reset_update(rcdev, id, true); +} + +static int jh7100_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return jh7100_reset_update(rcdev, id, false); +} + +static int jh7100_reset_reset(struct reset_controller_dev *rcdev, + unsigned long id) +{ + int ret; + + ret = jh7100_reset_assert(rcdev, id); + if (ret) + return ret; + + return jh7100_reset_deassert(rcdev, id); +} + +static int jh7100_reset_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct jh7100_reset *data = jh7100_reset_from(rcdev); + unsigned long offset = BIT_ULL_WORD(id); + u64 mask = BIT_ULL_MASK(id); + void __iomem *reg_status = data->base + JH7100_RESET_STATUS0 + offset * sizeof(u64); + u64 value = readq(reg_status); + + return !((value ^ jh7100_reset_asserted[offset]) & mask); +} + +static const struct reset_control_ops jh7100_reset_ops = { + .assert = jh7100_reset_assert, + .deassert = jh7100_reset_deassert, + .reset = jh7100_reset_reset, + .status = jh7100_reset_status, +}; + +static int __init jh7100_reset_probe(struct platform_device *pdev) +{ + struct jh7100_reset *data; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + data->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(data->base)) + return PTR_ERR(data->base); + + data->rcdev.ops = &jh7100_reset_ops; + data->rcdev.owner = THIS_MODULE; + data->rcdev.nr_resets = JH7100_RSTN_END; + data->rcdev.dev = &pdev->dev; + data->rcdev.of_node = pdev->dev.of_node; + spin_lock_init(&data->lock); + + return devm_reset_controller_register(&pdev->dev, &data->rcdev); +} + +static const struct of_device_id jh7100_reset_dt_ids[] = { + { .compatible = "starfive,jh7100-reset" }, + { /* sentinel */ } +}; + +static struct platform_driver jh7100_reset_driver = { + .driver = { + .name = "jh7100-reset", + .of_match_table = jh7100_reset_dt_ids, + .suppress_bind_attrs = true, + }, +}; +builtin_platform_driver_probe(jh7100_reset_driver, jh7100_reset_probe); |