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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Real Time Clock driver for Conexant Digicolor
4 *
5 * Copyright (C) 2015 Paradox Innovation Ltd.
6 *
7 * Author: Baruch Siach <[email protected]>
8 */
9
10#include <linux/io.h>
11#include <linux/iopoll.h>
12#include <linux/delay.h>
13#include <linux/module.h>
14#include <linux/platform_device.h>
15#include <linux/rtc.h>
16#include <linux/of.h>
17
18#define DC_RTC_CONTROL 0x0
19#define DC_RTC_TIME 0x8
20#define DC_RTC_REFERENCE 0xc
21#define DC_RTC_ALARM 0x10
22#define DC_RTC_INTFLAG_CLEAR 0x14
23#define DC_RTC_INTENABLE 0x16
24
25#define DC_RTC_CMD_MASK 0xf
26#define DC_RTC_GO_BUSY BIT(7)
27
28#define CMD_NOP 0
29#define CMD_RESET 1
30#define CMD_WRITE 3
31#define CMD_READ 4
32
33#define CMD_DELAY_US (10*1000)
34#define CMD_TIMEOUT_US (500*CMD_DELAY_US)
35
36struct dc_rtc {
37 struct rtc_device *rtc_dev;
38 void __iomem *regs;
39};
40
41static int dc_rtc_cmds(struct dc_rtc *rtc, const u8 *cmds, int len)
42{
43 u8 val;
44 int i, ret;
45
46 for (i = 0; i < len; i++) {
47 writeb_relaxed((cmds[i] & DC_RTC_CMD_MASK) | DC_RTC_GO_BUSY,
48 rtc->regs + DC_RTC_CONTROL);
49 ret = readb_relaxed_poll_timeout(
50 rtc->regs + DC_RTC_CONTROL, val,
51 !(val & DC_RTC_GO_BUSY), CMD_DELAY_US, CMD_TIMEOUT_US);
52 if (ret < 0)
53 return ret;
54 }
55
56 return 0;
57}
58
59static int dc_rtc_read(struct dc_rtc *rtc, unsigned long *val)
60{
61 static const u8 read_cmds[] = {CMD_READ, CMD_NOP};
62 u32 reference, time1, time2;
63 int ret;
64
65 ret = dc_rtc_cmds(rtc, read_cmds, ARRAY_SIZE(read_cmds));
66 if (ret < 0)
67 return ret;
68
69 reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
70 time1 = readl_relaxed(rtc->regs + DC_RTC_TIME);
71 /* Read twice to ensure consistency */
72 while (1) {
73 time2 = readl_relaxed(rtc->regs + DC_RTC_TIME);
74 if (time1 == time2)
75 break;
76 time1 = time2;
77 }
78
79 *val = reference + time1;
80 return 0;
81}
82
83static int dc_rtc_write(struct dc_rtc *rtc, u32 val)
84{
85 static const u8 write_cmds[] = {CMD_WRITE, CMD_NOP, CMD_RESET, CMD_NOP};
86
87 writel_relaxed(val, rtc->regs + DC_RTC_REFERENCE);
88 return dc_rtc_cmds(rtc, write_cmds, ARRAY_SIZE(write_cmds));
89}
90
91static int dc_rtc_read_time(struct device *dev, struct rtc_time *tm)
92{
93 struct dc_rtc *rtc = dev_get_drvdata(dev);
94 unsigned long now;
95 int ret;
96
97 ret = dc_rtc_read(rtc, &now);
98 if (ret < 0)
99 return ret;
100 rtc_time64_to_tm(now, tm);
101
102 return 0;
103}
104
105static int dc_rtc_set_time(struct device *dev, struct rtc_time *tm)
106{
107 struct dc_rtc *rtc = dev_get_drvdata(dev);
108
109 return dc_rtc_write(rtc, rtc_tm_to_time64(tm));
110}
111
112static int dc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
113{
114 struct dc_rtc *rtc = dev_get_drvdata(dev);
115 u32 alarm_reg, reference;
116 unsigned long now;
117 int ret;
118
119 alarm_reg = readl_relaxed(rtc->regs + DC_RTC_ALARM);
120 reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
121 rtc_time64_to_tm(reference + alarm_reg, &alarm->time);
122
123 ret = dc_rtc_read(rtc, &now);
124 if (ret < 0)
125 return ret;
126
127 alarm->pending = alarm_reg + reference > now;
128 alarm->enabled = readl_relaxed(rtc->regs + DC_RTC_INTENABLE);
129
130 return 0;
131}
132
133static int dc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
134{
135 struct dc_rtc *rtc = dev_get_drvdata(dev);
136 time64_t alarm_time;
137 u32 reference;
138
139 alarm_time = rtc_tm_to_time64(&alarm->time);
140
141 reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
142 writel_relaxed(alarm_time - reference, rtc->regs + DC_RTC_ALARM);
143
144 writeb_relaxed(!!alarm->enabled, rtc->regs + DC_RTC_INTENABLE);
145
146 return 0;
147}
148
149static int dc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
150{
151 struct dc_rtc *rtc = dev_get_drvdata(dev);
152
153 writeb_relaxed(!!enabled, rtc->regs + DC_RTC_INTENABLE);
154
155 return 0;
156}
157
158static const struct rtc_class_ops dc_rtc_ops = {
159 .read_time = dc_rtc_read_time,
160 .set_time = dc_rtc_set_time,
161 .read_alarm = dc_rtc_read_alarm,
162 .set_alarm = dc_rtc_set_alarm,
163 .alarm_irq_enable = dc_rtc_alarm_irq_enable,
164};
165
166static irqreturn_t dc_rtc_irq(int irq, void *dev_id)
167{
168 struct dc_rtc *rtc = dev_id;
169
170 writeb_relaxed(1, rtc->regs + DC_RTC_INTFLAG_CLEAR);
171 rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
172
173 return IRQ_HANDLED;
174}
175
176static int __init dc_rtc_probe(struct platform_device *pdev)
177{
178 struct dc_rtc *rtc;
179 int irq, ret;
180
181 rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
182 if (!rtc)
183 return -ENOMEM;
184
185 rtc->regs = devm_platform_ioremap_resource(pdev, 0);
186 if (IS_ERR(rtc->regs))
187 return PTR_ERR(rtc->regs);
188
189 rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
190 if (IS_ERR(rtc->rtc_dev))
191 return PTR_ERR(rtc->rtc_dev);
192
193 irq = platform_get_irq(pdev, 0);
194 if (irq < 0)
195 return irq;
196 ret = devm_request_irq(&pdev->dev, irq, dc_rtc_irq, 0, pdev->name, rtc);
197 if (ret < 0)
198 return ret;
199
200 platform_set_drvdata(pdev, rtc);
201
202 rtc->rtc_dev->ops = &dc_rtc_ops;
203 rtc->rtc_dev->range_max = U32_MAX;
204
205 return devm_rtc_register_device(rtc->rtc_dev);
206}
207
208static const __maybe_unused struct of_device_id dc_dt_ids[] = {
209 { .compatible = "cnxt,cx92755-rtc" },
210 { /* sentinel */ }
211};
212MODULE_DEVICE_TABLE(of, dc_dt_ids);
213
214static struct platform_driver dc_rtc_driver = {
215 .driver = {
216 .name = "digicolor_rtc",
217 .of_match_table = of_match_ptr(dc_dt_ids),
218 },
219};
220module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe);
221
222MODULE_AUTHOR("Baruch Siach <[email protected]>");
223MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)");
224MODULE_LICENSE("GPL");