1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Reset driver for NXP LPC18xx/43xx Reset Generation Unit (RGU). 4 * 5 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com> 6 */ 7 8 #include <linux/clk.h> 9 #include <linux/delay.h> 10 #include <linux/err.h> 11 #include <linux/io.h> 12 #include <linux/init.h> 13 #include <linux/of.h> 14 #include <linux/platform_device.h> 15 #include <linux/reboot.h> 16 #include <linux/reset-controller.h> 17 #include <linux/spinlock.h> 18 19 /* LPC18xx RGU registers */ 20 #define LPC18XX_RGU_CTRL0 0x100 21 #define LPC18XX_RGU_CTRL1 0x104 22 #define LPC18XX_RGU_ACTIVE_STATUS0 0x150 23 #define LPC18XX_RGU_ACTIVE_STATUS1 0x154 24 25 #define LPC18XX_RGU_RESETS_PER_REG 32 26 27 /* Internal reset outputs */ 28 #define LPC18XX_RGU_CORE_RST 0 29 #define LPC43XX_RGU_M0SUB_RST 12 30 #define LPC43XX_RGU_M0APP_RST 56 31 32 struct lpc18xx_rgu_data { 33 struct reset_controller_dev rcdev; 34 struct notifier_block restart_nb; 35 struct clk *clk_delay; 36 struct clk *clk_reg; 37 void __iomem *base; 38 spinlock_t lock; 39 u32 delay_us; 40 }; 41 42 #define to_rgu_data(p) container_of(p, struct lpc18xx_rgu_data, rcdev) 43 44 static int lpc18xx_rgu_restart(struct notifier_block *nb, unsigned long mode, 45 void *cmd) 46 { 47 struct lpc18xx_rgu_data *rc = container_of(nb, struct lpc18xx_rgu_data, 48 restart_nb); 49 50 writel(BIT(LPC18XX_RGU_CORE_RST), rc->base + LPC18XX_RGU_CTRL0); 51 mdelay(2000); 52 53 pr_emerg("%s: unable to restart system\n", __func__); 54 55 return NOTIFY_DONE; 56 } 57 58 /* 59 * The LPC18xx RGU has mostly self-deasserting resets except for the 60 * two reset lines going to the internal Cortex-M0 cores. 61 * 62 * To prevent the M0 core resets from accidentally getting deasserted 63 * status register must be check and bits in control register set to 64 * preserve the state. 65 */ 66 static int lpc18xx_rgu_setclear_reset(struct reset_controller_dev *rcdev, 67 unsigned long id, bool set) 68 { 69 struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev); 70 u32 stat_offset = LPC18XX_RGU_ACTIVE_STATUS0; 71 u32 ctrl_offset = LPC18XX_RGU_CTRL0; 72 unsigned long flags; 73 u32 stat, rst_bit; 74 75 stat_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32); 76 ctrl_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32); 77 rst_bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG); 78 79 spin_lock_irqsave(&rc->lock, flags); 80 stat = ~readl(rc->base + stat_offset); 81 if (set) 82 writel(stat | rst_bit, rc->base + ctrl_offset); 83 else 84 writel(stat & ~rst_bit, rc->base + ctrl_offset); 85 spin_unlock_irqrestore(&rc->lock, flags); 86 87 return 0; 88 } 89 90 static int lpc18xx_rgu_assert(struct reset_controller_dev *rcdev, 91 unsigned long id) 92 { 93 return lpc18xx_rgu_setclear_reset(rcdev, id, true); 94 } 95 96 static int lpc18xx_rgu_deassert(struct reset_controller_dev *rcdev, 97 unsigned long id) 98 { 99 return lpc18xx_rgu_setclear_reset(rcdev, id, false); 100 } 101 102 /* Only M0 cores require explicit reset deassert */ 103 static int lpc18xx_rgu_reset(struct reset_controller_dev *rcdev, 104 unsigned long id) 105 { 106 struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev); 107 108 lpc18xx_rgu_assert(rcdev, id); 109 udelay(rc->delay_us); 110 111 switch (id) { 112 case LPC43XX_RGU_M0SUB_RST: 113 case LPC43XX_RGU_M0APP_RST: 114 lpc18xx_rgu_setclear_reset(rcdev, id, false); 115 } 116 117 return 0; 118 } 119 120 static int lpc18xx_rgu_status(struct reset_controller_dev *rcdev, 121 unsigned long id) 122 { 123 struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev); 124 u32 bit, offset = LPC18XX_RGU_ACTIVE_STATUS0; 125 126 offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32); 127 bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG); 128 129 return !(readl(rc->base + offset) & bit); 130 } 131 132 static const struct reset_control_ops lpc18xx_rgu_ops = { 133 .reset = lpc18xx_rgu_reset, 134 .assert = lpc18xx_rgu_assert, 135 .deassert = lpc18xx_rgu_deassert, 136 .status = lpc18xx_rgu_status, 137 }; 138 139 static int lpc18xx_rgu_probe(struct platform_device *pdev) 140 { 141 struct lpc18xx_rgu_data *rc; 142 u32 fcclk, firc; 143 int ret; 144 145 rc = devm_kzalloc(&pdev->dev, sizeof(*rc), GFP_KERNEL); 146 if (!rc) 147 return -ENOMEM; 148 149 rc->base = devm_platform_ioremap_resource(pdev, 0); 150 if (IS_ERR(rc->base)) 151 return PTR_ERR(rc->base); 152 153 rc->clk_reg = devm_clk_get(&pdev->dev, "reg"); 154 if (IS_ERR(rc->clk_reg)) { 155 dev_err(&pdev->dev, "reg clock not found\n"); 156 return PTR_ERR(rc->clk_reg); 157 } 158 159 rc->clk_delay = devm_clk_get(&pdev->dev, "delay"); 160 if (IS_ERR(rc->clk_delay)) { 161 dev_err(&pdev->dev, "delay clock not found\n"); 162 return PTR_ERR(rc->clk_delay); 163 } 164 165 ret = clk_prepare_enable(rc->clk_reg); 166 if (ret) { 167 dev_err(&pdev->dev, "unable to enable reg clock\n"); 168 return ret; 169 } 170 171 ret = clk_prepare_enable(rc->clk_delay); 172 if (ret) { 173 dev_err(&pdev->dev, "unable to enable delay clock\n"); 174 goto dis_clk_reg; 175 } 176 177 fcclk = clk_get_rate(rc->clk_reg) / USEC_PER_SEC; 178 firc = clk_get_rate(rc->clk_delay) / USEC_PER_SEC; 179 if (fcclk == 0 || firc == 0) 180 rc->delay_us = 2; 181 else 182 rc->delay_us = DIV_ROUND_UP(fcclk, firc * firc); 183 184 spin_lock_init(&rc->lock); 185 186 rc->rcdev.owner = THIS_MODULE; 187 rc->rcdev.nr_resets = 64; 188 rc->rcdev.ops = &lpc18xx_rgu_ops; 189 rc->rcdev.of_node = pdev->dev.of_node; 190 191 ret = reset_controller_register(&rc->rcdev); 192 if (ret) { 193 dev_err(&pdev->dev, "unable to register device\n"); 194 goto dis_clks; 195 } 196 197 rc->restart_nb.priority = 192, 198 rc->restart_nb.notifier_call = lpc18xx_rgu_restart, 199 ret = register_restart_handler(&rc->restart_nb); 200 if (ret) 201 dev_warn(&pdev->dev, "failed to register restart handler\n"); 202 203 return 0; 204 205 dis_clks: 206 clk_disable_unprepare(rc->clk_delay); 207 dis_clk_reg: 208 clk_disable_unprepare(rc->clk_reg); 209 210 return ret; 211 } 212 213 static const struct of_device_id lpc18xx_rgu_match[] = { 214 { .compatible = "nxp,lpc1850-rgu" }, 215 { } 216 }; 217 218 static struct platform_driver lpc18xx_rgu_driver = { 219 .probe = lpc18xx_rgu_probe, 220 .driver = { 221 .name = "lpc18xx-reset", 222 .of_match_table = lpc18xx_rgu_match, 223 .suppress_bind_attrs = true, 224 }, 225 }; 226 builtin_platform_driver(lpc18xx_rgu_driver); 227