1 /* 2 * Real Time Clock driver for Conexant Digicolor 3 * 4 * Copyright (C) 2015 Paradox Innovation Ltd. 5 * 6 * Author: Baruch Siach <baruch@tkos.co.il> 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms of the GNU General Public License as published by the 10 * Free Software Foundation; either version 2 of the License, or (at your 11 * option) any later version. 12 */ 13 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 40 struct dc_rtc { 41 struct rtc_device *rtc_dev; 42 void __iomem *regs; 43 }; 44 45 static 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 63 static 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 /* Read twice to ensure consistency */ 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 87 static 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 95 static 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 } 108 109 static 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 } 115 116 static 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 } 136 137 static 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 } 152 153 static 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 } 161 162 static 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 }; 169 170 static 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 } 179 180 static 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 } 210 211 static const struct of_device_id dc_dt_ids[] = { 212 { .compatible = "cnxt,cx92755-rtc" }, 213 { /* sentinel */ } 214 }; 215 MODULE_DEVICE_TABLE(of, dc_dt_ids); 216 217 static struct platform_driver dc_rtc_driver = { 218 .driver = { 219 .name = "digicolor_rtc", 220 .of_match_table = of_match_ptr(dc_dt_ids), 221 }, 222 }; 223 module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe); 224 225 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); 226 MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)"); 227 MODULE_LICENSE("GPL"); 228