1 /*
2 * Reset driver for NXP LPC18xx/43xx Reset Generation Unit (RGU).
3 *
4 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 */
11
12 #include <linux/clk.h>
13 #include <linux/delay.h>
14 #include <linux/err.h>
15 #include <linux/io.h>
16 #include <linux/init.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/reboot.h>
20 #include <linux/reset-controller.h>
21 #include <linux/spinlock.h>
22
23 /* LPC18xx RGU registers */
24 #define LPC18XX_RGU_CTRL0 0x100
25 #define LPC18XX_RGU_CTRL1 0x104
26 #define LPC18XX_RGU_ACTIVE_STATUS0 0x150
27 #define LPC18XX_RGU_ACTIVE_STATUS1 0x154
28
29 #define LPC18XX_RGU_RESETS_PER_REG 32
30
31 /* Internal reset outputs */
32 #define LPC18XX_RGU_CORE_RST 0
33 #define LPC43XX_RGU_M0SUB_RST 12
34 #define LPC43XX_RGU_M0APP_RST 56
35
36 struct lpc18xx_rgu_data {
37 struct reset_controller_dev rcdev;
38 struct notifier_block restart_nb;
39 struct clk *clk_delay;
40 struct clk *clk_reg;
41 void __iomem *base;
42 spinlock_t lock;
43 u32 delay_us;
44 };
45
46 #define to_rgu_data(p) container_of(p, struct lpc18xx_rgu_data, rcdev)
47
lpc18xx_rgu_restart(struct notifier_block * nb,unsigned long mode,void * cmd)48 static int lpc18xx_rgu_restart(struct notifier_block *nb, unsigned long mode,
49 void *cmd)
50 {
51 struct lpc18xx_rgu_data *rc = container_of(nb, struct lpc18xx_rgu_data,
52 restart_nb);
53
54 writel(BIT(LPC18XX_RGU_CORE_RST), rc->base + LPC18XX_RGU_CTRL0);
55 mdelay(2000);
56
57 pr_emerg("%s: unable to restart system\n", __func__);
58
59 return NOTIFY_DONE;
60 }
61
62 /*
63 * The LPC18xx RGU has mostly self-deasserting resets except for the
64 * two reset lines going to the internal Cortex-M0 cores.
65 *
66 * To prevent the M0 core resets from accidentally getting deasserted
67 * status register must be check and bits in control register set to
68 * preserve the state.
69 */
lpc18xx_rgu_setclear_reset(struct reset_controller_dev * rcdev,unsigned long id,bool set)70 static int lpc18xx_rgu_setclear_reset(struct reset_controller_dev *rcdev,
71 unsigned long id, bool set)
72 {
73 struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
74 u32 stat_offset = LPC18XX_RGU_ACTIVE_STATUS0;
75 u32 ctrl_offset = LPC18XX_RGU_CTRL0;
76 unsigned long flags;
77 u32 stat, rst_bit;
78
79 stat_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
80 ctrl_offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
81 rst_bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
82
83 spin_lock_irqsave(&rc->lock, flags);
84 stat = ~readl(rc->base + stat_offset);
85 if (set)
86 writel(stat | rst_bit, rc->base + ctrl_offset);
87 else
88 writel(stat & ~rst_bit, rc->base + ctrl_offset);
89 spin_unlock_irqrestore(&rc->lock, flags);
90
91 return 0;
92 }
93
lpc18xx_rgu_assert(struct reset_controller_dev * rcdev,unsigned long id)94 static int lpc18xx_rgu_assert(struct reset_controller_dev *rcdev,
95 unsigned long id)
96 {
97 return lpc18xx_rgu_setclear_reset(rcdev, id, true);
98 }
99
lpc18xx_rgu_deassert(struct reset_controller_dev * rcdev,unsigned long id)100 static int lpc18xx_rgu_deassert(struct reset_controller_dev *rcdev,
101 unsigned long id)
102 {
103 return lpc18xx_rgu_setclear_reset(rcdev, id, false);
104 }
105
106 /* Only M0 cores require explicit reset deassert */
lpc18xx_rgu_reset(struct reset_controller_dev * rcdev,unsigned long id)107 static int lpc18xx_rgu_reset(struct reset_controller_dev *rcdev,
108 unsigned long id)
109 {
110 struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
111
112 lpc18xx_rgu_assert(rcdev, id);
113 udelay(rc->delay_us);
114
115 switch (id) {
116 case LPC43XX_RGU_M0SUB_RST:
117 case LPC43XX_RGU_M0APP_RST:
118 lpc18xx_rgu_setclear_reset(rcdev, id, false);
119 }
120
121 return 0;
122 }
123
lpc18xx_rgu_status(struct reset_controller_dev * rcdev,unsigned long id)124 static int lpc18xx_rgu_status(struct reset_controller_dev *rcdev,
125 unsigned long id)
126 {
127 struct lpc18xx_rgu_data *rc = to_rgu_data(rcdev);
128 u32 bit, offset = LPC18XX_RGU_ACTIVE_STATUS0;
129
130 offset += (id / LPC18XX_RGU_RESETS_PER_REG) * sizeof(u32);
131 bit = 1 << (id % LPC18XX_RGU_RESETS_PER_REG);
132
133 return !(readl(rc->base + offset) & bit);
134 }
135
136 static const struct reset_control_ops lpc18xx_rgu_ops = {
137 .reset = lpc18xx_rgu_reset,
138 .assert = lpc18xx_rgu_assert,
139 .deassert = lpc18xx_rgu_deassert,
140 .status = lpc18xx_rgu_status,
141 };
142
lpc18xx_rgu_probe(struct platform_device * pdev)143 static int lpc18xx_rgu_probe(struct platform_device *pdev)
144 {
145 struct lpc18xx_rgu_data *rc;
146 struct resource *res;
147 u32 fcclk, firc;
148 int ret;
149
150 rc = devm_kzalloc(&pdev->dev, sizeof(*rc), GFP_KERNEL);
151 if (!rc)
152 return -ENOMEM;
153
154 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
155 rc->base = devm_ioremap_resource(&pdev->dev, res);
156 if (IS_ERR(rc->base))
157 return PTR_ERR(rc->base);
158
159 rc->clk_reg = devm_clk_get(&pdev->dev, "reg");
160 if (IS_ERR(rc->clk_reg)) {
161 dev_err(&pdev->dev, "reg clock not found\n");
162 return PTR_ERR(rc->clk_reg);
163 }
164
165 rc->clk_delay = devm_clk_get(&pdev->dev, "delay");
166 if (IS_ERR(rc->clk_delay)) {
167 dev_err(&pdev->dev, "delay clock not found\n");
168 return PTR_ERR(rc->clk_delay);
169 }
170
171 ret = clk_prepare_enable(rc->clk_reg);
172 if (ret) {
173 dev_err(&pdev->dev, "unable to enable reg clock\n");
174 return ret;
175 }
176
177 ret = clk_prepare_enable(rc->clk_delay);
178 if (ret) {
179 dev_err(&pdev->dev, "unable to enable delay clock\n");
180 goto dis_clk_reg;
181 }
182
183 fcclk = clk_get_rate(rc->clk_reg) / USEC_PER_SEC;
184 firc = clk_get_rate(rc->clk_delay) / USEC_PER_SEC;
185 if (fcclk == 0 || firc == 0)
186 rc->delay_us = 2;
187 else
188 rc->delay_us = DIV_ROUND_UP(fcclk, firc * firc);
189
190 spin_lock_init(&rc->lock);
191
192 rc->rcdev.owner = THIS_MODULE;
193 rc->rcdev.nr_resets = 64;
194 rc->rcdev.ops = &lpc18xx_rgu_ops;
195 rc->rcdev.of_node = pdev->dev.of_node;
196
197 platform_set_drvdata(pdev, rc);
198
199 ret = reset_controller_register(&rc->rcdev);
200 if (ret) {
201 dev_err(&pdev->dev, "unable to register device\n");
202 goto dis_clks;
203 }
204
205 rc->restart_nb.priority = 192,
206 rc->restart_nb.notifier_call = lpc18xx_rgu_restart,
207 ret = register_restart_handler(&rc->restart_nb);
208 if (ret)
209 dev_warn(&pdev->dev, "failed to register restart handler\n");
210
211 return 0;
212
213 dis_clks:
214 clk_disable_unprepare(rc->clk_delay);
215 dis_clk_reg:
216 clk_disable_unprepare(rc->clk_reg);
217
218 return ret;
219 }
220
221 static const struct of_device_id lpc18xx_rgu_match[] = {
222 { .compatible = "nxp,lpc1850-rgu" },
223 { }
224 };
225
226 static struct platform_driver lpc18xx_rgu_driver = {
227 .probe = lpc18xx_rgu_probe,
228 .driver = {
229 .name = "lpc18xx-reset",
230 .of_match_table = lpc18xx_rgu_match,
231 .suppress_bind_attrs = true,
232 },
233 };
234 builtin_platform_driver(lpc18xx_rgu_driver);
235