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/*
* Reset driver for NXP LPC18xx/43xx Reset Generation Unit (RGU).
*
* Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
*
* 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.
*
*/
#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);
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