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14#include <linux/io.h>
15#include <linux/iopoll.h>
16#include <linux/delay.h>
17#include <linux/module.h>
18#include <linux/platform_device.h>
19#include <linux/rtc.h>
20#include <linux/of.h>
21
22#define DC_RTC_CONTROL 0x0
23#define DC_RTC_TIME 0x8
24#define DC_RTC_REFERENCE 0xc
25#define DC_RTC_ALARM 0x10
26#define DC_RTC_INTFLAG_CLEAR 0x14
27#define DC_RTC_INTENABLE 0x16
28
29#define DC_RTC_CMD_MASK 0xf
30#define DC_RTC_GO_BUSY BIT(7)
31
32#define CMD_NOP 0
33#define CMD_RESET 1
34#define CMD_WRITE 3
35#define CMD_READ 4
36
37#define CMD_DELAY_US (10*1000)
38#define CMD_TIMEOUT_US (500*CMD_DELAY_US)
39
40struct dc_rtc {
41 struct rtc_device *rtc_dev;
42 void __iomem *regs;
43};
44
45static int dc_rtc_cmds(struct dc_rtc *rtc, const u8 *cmds, int len)
46{
47 u8 val;
48 int i, ret;
49
50 for (i = 0; i < len; i++) {
51 writeb_relaxed((cmds[i] & DC_RTC_CMD_MASK) | DC_RTC_GO_BUSY,
52 rtc->regs + DC_RTC_CONTROL);
53 ret = readb_relaxed_poll_timeout(
54 rtc->regs + DC_RTC_CONTROL, val,
55 !(val & DC_RTC_GO_BUSY), CMD_DELAY_US, CMD_TIMEOUT_US);
56 if (ret < 0)
57 return ret;
58 }
59
60 return 0;
61}
62
63static int dc_rtc_read(struct dc_rtc *rtc, unsigned long *val)
64{
65 static const u8 read_cmds[] = {CMD_READ, CMD_NOP};
66 u32 reference, time1, time2;
67 int ret;
68
69 ret = dc_rtc_cmds(rtc, read_cmds, ARRAY_SIZE(read_cmds));
70 if (ret < 0)
71 return ret;
72
73 reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
74 time1 = readl_relaxed(rtc->regs + DC_RTC_TIME);
75
76 while (1) {
77 time2 = readl_relaxed(rtc->regs + DC_RTC_TIME);
78 if (time1 == time2)
79 break;
80 time1 = time2;
81 }
82
83 *val = reference + time1;
84 return 0;
85}
86
87static int dc_rtc_write(struct dc_rtc *rtc, u32 val)
88{
89 static const u8 write_cmds[] = {CMD_WRITE, CMD_NOP, CMD_RESET, CMD_NOP};
90
91 writel_relaxed(val, rtc->regs + DC_RTC_REFERENCE);
92 return dc_rtc_cmds(rtc, write_cmds, ARRAY_SIZE(write_cmds));
93}
94
95static int dc_rtc_read_time(struct device *dev, struct rtc_time *tm)
96{
97 struct dc_rtc *rtc = dev_get_drvdata(dev);
98 unsigned long now;
99 int ret;
100
101 ret = dc_rtc_read(rtc, &now);
102 if (ret < 0)
103 return ret;
104 rtc_time64_to_tm(now, tm);
105
106 return 0;
107}
108
109static int dc_rtc_set_mmss(struct device *dev, unsigned long secs)
110{
111 struct dc_rtc *rtc = dev_get_drvdata(dev);
112
113 return dc_rtc_write(rtc, secs);
114}
115
116static int dc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
117{
118 struct dc_rtc *rtc = dev_get_drvdata(dev);
119 u32 alarm_reg, reference;
120 unsigned long now;
121 int ret;
122
123 alarm_reg = readl_relaxed(rtc->regs + DC_RTC_ALARM);
124 reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
125 rtc_time64_to_tm(reference + alarm_reg, &alarm->time);
126
127 ret = dc_rtc_read(rtc, &now);
128 if (ret < 0)
129 return ret;
130
131 alarm->pending = alarm_reg + reference > now;
132 alarm->enabled = readl_relaxed(rtc->regs + DC_RTC_INTENABLE);
133
134 return 0;
135}
136
137static int dc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
138{
139 struct dc_rtc *rtc = dev_get_drvdata(dev);
140 time64_t alarm_time;
141 u32 reference;
142
143 alarm_time = rtc_tm_to_time64(&alarm->time);
144
145 reference = readl_relaxed(rtc->regs + DC_RTC_REFERENCE);
146 writel_relaxed(alarm_time - reference, rtc->regs + DC_RTC_ALARM);
147
148 writeb_relaxed(!!alarm->enabled, rtc->regs + DC_RTC_INTENABLE);
149
150 return 0;
151}
152
153static int dc_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
154{
155 struct dc_rtc *rtc = dev_get_drvdata(dev);
156
157 writeb_relaxed(!!enabled, rtc->regs + DC_RTC_INTENABLE);
158
159 return 0;
160}
161
162static const struct rtc_class_ops dc_rtc_ops = {
163 .read_time = dc_rtc_read_time,
164 .set_mmss = dc_rtc_set_mmss,
165 .read_alarm = dc_rtc_read_alarm,
166 .set_alarm = dc_rtc_set_alarm,
167 .alarm_irq_enable = dc_rtc_alarm_irq_enable,
168};
169
170static irqreturn_t dc_rtc_irq(int irq, void *dev_id)
171{
172 struct dc_rtc *rtc = dev_id;
173
174 writeb_relaxed(1, rtc->regs + DC_RTC_INTFLAG_CLEAR);
175 rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
176
177 return IRQ_HANDLED;
178}
179
180static int __init dc_rtc_probe(struct platform_device *pdev)
181{
182 struct resource *res;
183 struct dc_rtc *rtc;
184 int irq, ret;
185
186 rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
187 if (!rtc)
188 return -ENOMEM;
189
190 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
191 rtc->regs = devm_ioremap_resource(&pdev->dev, res);
192 if (IS_ERR(rtc->regs))
193 return PTR_ERR(rtc->regs);
194
195 irq = platform_get_irq(pdev, 0);
196 if (irq < 0)
197 return irq;
198 ret = devm_request_irq(&pdev->dev, irq, dc_rtc_irq, 0, pdev->name, rtc);
199 if (ret < 0)
200 return ret;
201
202 platform_set_drvdata(pdev, rtc);
203 rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
204 &dc_rtc_ops, THIS_MODULE);
205 if (IS_ERR(rtc->rtc_dev))
206 return PTR_ERR(rtc->rtc_dev);
207
208 return 0;
209}
210
211static const struct of_device_id dc_dt_ids[] = {
212 { .compatible = "cnxt,cx92755-rtc" },
213 { }
214};
215MODULE_DEVICE_TABLE(of, dc_dt_ids);
216
217static struct platform_driver dc_rtc_driver = {
218 .driver = {
219 .name = "digicolor_rtc",
220 .of_match_table = of_match_ptr(dc_dt_ids),
221 },
222};
223module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe);
224
225MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
226MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)");
227MODULE_LICENSE("GPL");
228
