Baruch Siach | ba17220 | 2015-04-16 12:45:40 -0700 | [diff] [blame] | 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"); |