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 <baruch@tkos.co.il> 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 36 struct dc_rtc { 37 struct rtc_device *rtc_dev; 38 void __iomem *regs; 39 }; 40 41 static 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 59 static 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 83 static 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 91 static 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 } 104 105 static 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 } 111 112 static 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 } 132 133 static 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 } 148 149 static 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 } 157 158 static 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 }; 165 166 static 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 } 175 176 static int __init dc_rtc_probe(struct platform_device *pdev) 177 { 178 struct resource *res; 179 struct dc_rtc *rtc; 180 int irq, ret; 181 182 rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL); 183 if (!rtc) 184 return -ENOMEM; 185 186 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 187 rtc->regs = devm_ioremap_resource(&pdev->dev, res); 188 if (IS_ERR(rtc->regs)) 189 return PTR_ERR(rtc->regs); 190 191 rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev); 192 if (IS_ERR(rtc->rtc_dev)) 193 return PTR_ERR(rtc->rtc_dev); 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); 203 204 rtc->rtc_dev->ops = &dc_rtc_ops; 205 rtc->rtc_dev->range_max = U32_MAX; 206 207 return rtc_register_device(rtc->rtc_dev); 208 } 209 210 static const struct of_device_id dc_dt_ids[] = { 211 { .compatible = "cnxt,cx92755-rtc" }, 212 { /* sentinel */ } 213 }; 214 MODULE_DEVICE_TABLE(of, dc_dt_ids); 215 216 static struct platform_driver dc_rtc_driver = { 217 .driver = { 218 .name = "digicolor_rtc", 219 .of_match_table = of_match_ptr(dc_dt_ids), 220 }, 221 }; 222 module_platform_driver_probe(dc_rtc_driver, dc_rtc_probe); 223 224 MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); 225 MODULE_DESCRIPTION("Conexant Digicolor Realtime Clock Driver (RTC)"); 226 MODULE_LICENSE("GPL"); 227