diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/reset/reset-lpc18xx.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/drivers/reset/reset-lpc18xx.c b/drivers/reset/reset-lpc18xx.c new file mode 100644 index 000000000..35d8dd4cc --- /dev/null +++ b/drivers/reset/reset-lpc18xx.c @@ -0,0 +1,230 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Reset driver for NXP LPC18xx/43xx Reset Generation Unit (RGU). + * + * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com> + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/init.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/reboot.h> +#include <linux/reset-controller.h> +#include <linux/spinlock.h> + +/* LPC18xx RGU registers */ +#define LPC18XX_RGU_CTRL0 0x100 +#define LPC18XX_RGU_CTRL1 0x104 +#define LPC18XX_RGU_ACTIVE_STATUS0 0x150 +#define LPC18XX_RGU_ACTIVE_STATUS1 0x154 + +#define LPC18XX_RGU_RESETS_PER_REG 32 + +/* Internal reset outputs */ +#define LPC18XX_RGU_CORE_RST 0 +#define LPC43XX_RGU_M0SUB_RST 12 +#define LPC43XX_RGU_M0APP_RST 56 + +struct lpc18xx_rgu_data { + struct reset_controller_dev rcdev; + struct notifier_block restart_nb; + struct clk *clk_delay; + struct clk *clk_reg; + void __iomem *base; + spinlock_t lock; + u32 delay_us; +}; + +#define to_rgu_data(p) container_of(p, struct lpc18xx_rgu_data, rcdev) + +static int lpc18xx_rgu_restart(struct notifier_block *nb, unsigned long mode, + void *cmd) +{ + struct lpc18xx_rgu_data *rc = container_of(nb, struct lpc18xx_rgu_data, + restart_nb); + + writel(BIT(LPC18XX_RGU_CORE_RST), rc->base + LPC18XX_RGU_CTRL0); + mdelay(2000); + + pr_emerg("%s: unable to restart system\n", __func__); + + return NOTIFY_DONE; +} + +/* + * The LPC18xx RGU has mostly self-deasserting resets except for the + * two reset lines going to the internal Cortex-M0 cores. + * + * To prevent the M0 core resets from accidentally getting deasserted + * status register must be check and bits in control register set to + * preserve the state. + */ +static int lpc18xx_rgu_setclear_reset(struct reset_controller_dev *rcdev, + unsigned long id, bool set) +{ + struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev); + u32 stat_offset = LPC18XX_RGU_ACTIVE_STATUS0; + u32 ctrl_offset = LPC18XX_RGU_CTRL0; + unsigned long flags; + u32 stat, rst_bit; + + stat_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32); + ctrl_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32); + rst_bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG); + + spin_lock_irqsave(&rc->lock, flags); + stat = ~readl(rc->base + stat_offset); + if (set) + writel(stat | rst_bit, rc->base + ctrl_offset); + else + writel(stat & ~rst_bit, rc->base + ctrl_offset); + spin_unlock_irqrestore(&rc->lock, flags); + + return 0; +} + +static int lpc18xx_rgu_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return lpc18xx_rgu_setclear_reset(rcdev, id, true); +} + +static int lpc18xx_rgu_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + return lpc18xx_rgu_setclear_reset(rcdev, id, false); +} + +/* Only M0 cores require explicit reset deassert */ +static int lpc18xx_rgu_reset(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev); + + lpc18xx_rgu_assert(rcdev, id); + udelay(rc->delay_us); + + switch (id) { + case LPC43XX_RGU_M0SUB_RST: + case LPC43XX_RGU_M0APP_RST: + lpc18xx_rgu_setclear_reset(rcdev, id, false); + } + + return 0; +} + +static int lpc18xx_rgu_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev); + u32 bit, offset = LPC18XX_RGU_ACTIVE_STATUS0; + + offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32); + bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG); + + return !(readl(rc->base + offset) & bit); +} + +static const struct reset_control_ops lpc18xx_rgu_ops = { + .reset = lpc18xx_rgu_reset, + .assert = lpc18xx_rgu_assert, + .deassert = lpc18xx_rgu_deassert, + .status = lpc18xx_rgu_status, +}; + +static int lpc18xx_rgu_probe(struct platform_device *pdev) +{ + struct lpc18xx_rgu_data *rc; + struct resource *res; + u32 fcclk, firc; + int ret; + + rc = devm_kzalloc(&pdev->dev, sizeof(*rc), GFP_KERNEL); + if (!rc) + return -ENOMEM; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + rc->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(rc->base)) + return PTR_ERR(rc->base); + + rc->clk_reg = devm_clk_get(&pdev->dev, "reg"); + if (IS_ERR(rc->clk_reg)) { + dev_err(&pdev->dev, "reg clock not found\n"); + return PTR_ERR(rc->clk_reg); + } + + rc->clk_delay = devm_clk_get(&pdev->dev, "delay"); + if (IS_ERR(rc->clk_delay)) { + dev_err(&pdev->dev, "delay clock not found\n"); + return PTR_ERR(rc->clk_delay); + } + + ret = clk_prepare_enable(rc->clk_reg); + if (ret) { + dev_err(&pdev->dev, "unable to enable reg clock\n"); + return ret; + } + + ret = clk_prepare_enable(rc->clk_delay); + if (ret) { + dev_err(&pdev->dev, "unable to enable delay clock\n"); + goto dis_clk_reg; + } + + fcclk = clk_get_rate(rc->clk_reg) / USEC_PER_SEC; + firc = clk_get_rate(rc->clk_delay) / USEC_PER_SEC; + if (fcclk == 0 || firc == 0) + rc->delay_us = 2; + else + rc->delay_us = DIV_ROUND_UP(fcclk, firc * firc); + + spin_lock_init(&rc->lock); + + rc->rcdev.owner = THIS_MODULE; + rc->rcdev.nr_resets = 64; + rc->rcdev.ops = &lpc18xx_rgu_ops; + rc->rcdev.of_node = pdev->dev.of_node; + + platform_set_drvdata(pdev, rc); + + ret = reset_controller_register(&rc->rcdev); + if (ret) { + dev_err(&pdev->dev, "unable to register device\n"); + goto dis_clks; + } + + rc->restart_nb.priority = 192, + rc->restart_nb.notifier_call = lpc18xx_rgu_restart, + ret = register_restart_handler(&rc->restart_nb); + if (ret) + dev_warn(&pdev->dev, "failed to register restart handler\n"); + + return 0; + +dis_clks: + clk_disable_unprepare(rc->clk_delay); +dis_clk_reg: + clk_disable_unprepare(rc->clk_reg); + + return ret; +} + +static const struct of_device_id lpc18xx_rgu_match[] = { + { .compatible = "nxp,lpc1850-rgu" }, + { } +}; + +static struct platform_driver lpc18xx_rgu_driver = { + .probe = lpc18xx_rgu_probe, + .driver = { + .name = "lpc18xx-reset", + .of_match_table = lpc18xx_rgu_match, + .suppress_bind_attrs = true, + }, +}; +builtin_platform_driver(lpc18xx_rgu_driver); |