drivers/rtc/rtc-xgene.c

   1 /*
   2  * APM X-Gene SoC Real Time Clock Driver
   3  *
   4  * Copyright (c) 2014, Applied Micro Circuits Corporation
   5  * Author: Rameshwar Prasad Sahu <rsahu@apm.com>
   6  *         Loc Ho <lho@apm.com>
   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  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20  *
  21  */
  22
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/of.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/io.h>
  28 #include <linux/slab.h>
  29 #include <linux/clk.h>
  30 #include <linux/delay.h>
  31 #include <linux/rtc.h>
  32
  33 /* RTC CSR Registers */
  34 #define RTC_CCVR                0x00
  35 #define RTC_CMR                 0x04
  36 #define RTC_CLR                 0x08
  37 #define RTC_CCR                 0x0C
  38 #define  RTC_CCR_IE             BIT(0)
  39 #define  RTC_CCR_MASK           BIT(1)
  40 #define  RTC_CCR_EN             BIT(2)
  41 #define  RTC_CCR_WEN            BIT(3)
  42 #define RTC_STAT                0x10
  43 #define  RTC_STAT_BIT           BIT(0)
  44 #define RTC_RSTAT               0x14
  45 #define RTC_EOI                 0x18
  46 #define RTC_VER                 0x1C
  47
  48 struct xgene_rtc_dev {
  49         struct rtc_device *rtc;
  50         struct device *dev;
  51         unsigned long alarm_time;
  52         void __iomem *csr_base;
  53         struct clk *clk;
  54         unsigned int irq_wake;
  55         unsigned int irq_enabled;
  56 };
  57
  58 static int xgene_rtc_read_time(struct device *dev, struct rtc_time *tm)
  59 {
  60         struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
  61
  62         rtc_time_to_tm(readl(pdata->csr_base + RTC_CCVR), tm);
  63         return 0;
  64 }
  65
  66 static int xgene_rtc_set_mmss(struct device *dev, unsigned long secs)
  67 {
  68         struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
  69
  70         /*
  71          * NOTE: After the following write, the RTC_CCVR is only reflected
  72          *       after the update cycle of 1 seconds.
  73          */
  74         writel((u32) secs, pdata->csr_base + RTC_CLR);
  75         readl(pdata->csr_base + RTC_CLR); /* Force a barrier */
  76
  77         return 0;
  78 }
  79
  80 static int xgene_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  81 {
  82         struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
  83
  84         rtc_time_to_tm(pdata->alarm_time, &alrm->time);
  85         alrm->enabled = readl(pdata->csr_base + RTC_CCR) & RTC_CCR_IE;
  86
  87         return 0;
  88 }
  89
  90 static int xgene_rtc_alarm_irq_enable(struct device *dev, u32 enabled)
  91 {
  92         struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
  93         u32 ccr;
  94
  95         ccr = readl(pdata->csr_base + RTC_CCR);
  96         if (enabled) {
  97                 ccr &= ~RTC_CCR_MASK;
  98                 ccr |= RTC_CCR_IE;
  99         } else {
 100                 ccr &= ~RTC_CCR_IE;
 101                 ccr |= RTC_CCR_MASK;
 102         }
 103         writel(ccr, pdata->csr_base + RTC_CCR);
 104
 105         return 0;
 106 }
 107
 108 static int xgene_rtc_alarm_irq_enabled(struct device *dev)
 109 {
 110         struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
 111
 112         return readl(pdata->csr_base + RTC_CCR) & RTC_CCR_IE ? 1 : 0;
 113 }
 114
 115 static int xgene_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 116 {
 117         struct xgene_rtc_dev *pdata = dev_get_drvdata(dev);
 118         unsigned long alarm_time;
 119
 120         rtc_tm_to_time(&alrm->time, &alarm_time);
 121         pdata->alarm_time = alarm_time;
 122         writel((u32) pdata->alarm_time, pdata->csr_base + RTC_CMR);
 123
 124         xgene_rtc_alarm_irq_enable(dev, alrm->enabled);
 125
 126         return 0;
 127 }
 128
 129 static const struct rtc_class_ops xgene_rtc_ops = {
 130         .read_time      = xgene_rtc_read_time,
 131         .set_mmss       = xgene_rtc_set_mmss,
 132         .read_alarm     = xgene_rtc_read_alarm,
 133         .set_alarm      = xgene_rtc_set_alarm,
 134         .alarm_irq_enable = xgene_rtc_alarm_irq_enable,
 135 };
 136
 137 static irqreturn_t xgene_rtc_interrupt(int irq, void *id)
 138 {
 139         struct xgene_rtc_dev *pdata = (struct xgene_rtc_dev *) id;
 140
 141         /* Check if interrupt asserted */
 142         if (!(readl(pdata->csr_base + RTC_STAT) & RTC_STAT_BIT))
 143                 return IRQ_NONE;
 144
 145         /* Clear interrupt */
 146         readl(pdata->csr_base + RTC_EOI);
 147
 148         rtc_update_irq(pdata->rtc, 1, RTC_IRQF | RTC_AF);
 149
 150         return IRQ_HANDLED;
 151 }
 152
 153 static int xgene_rtc_probe(struct platform_device *pdev)
 154 {
 155         struct xgene_rtc_dev *pdata;
 156         struct resource *res;
 157         int ret;
 158         int irq;
 159
 160         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 161         if (!pdata)
 162                 return -ENOMEM;
 163         platform_set_drvdata(pdev, pdata);
 164         pdata->dev = &pdev->dev;
 165
 166         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 167         pdata->csr_base = devm_ioremap_resource(&pdev->dev, res);
 168         if (IS_ERR(pdata->csr_base))
 169                 return PTR_ERR(pdata->csr_base);
 170
 171         irq = platform_get_irq(pdev, 0);
 172         if (irq < 0) {
 173                 dev_err(&pdev->dev, "No IRQ resource\n");
 174                 return irq;
 175         }
 176         ret = devm_request_irq(&pdev->dev, irq, xgene_rtc_interrupt, 0,
 177                                dev_name(&pdev->dev), pdata);
 178         if (ret) {
 179                 dev_err(&pdev->dev, "Could not request IRQ\n");
 180                 return ret;
 181         }
 182
 183         pdata->clk = devm_clk_get(&pdev->dev, NULL);
 184         if (IS_ERR(pdata->clk)) {
 185                 dev_err(&pdev->dev, "Couldn't get the clock for RTC\n");
 186                 return -ENODEV;
 187         }
 188         ret = clk_prepare_enable(pdata->clk);
 189         if (ret)
 190                 return ret;
 191
 192         /* Turn on the clock and the crystal */
 193         writel(RTC_CCR_EN, pdata->csr_base + RTC_CCR);
 194
 195         ret = device_init_wakeup(&pdev->dev, 1);
 196         if (ret) {
 197                 clk_disable_unprepare(pdata->clk);
 198                 return ret;
 199         }
 200
 201         pdata->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
 202                                          &xgene_rtc_ops, THIS_MODULE);
 203         if (IS_ERR(pdata->rtc)) {
 204                 clk_disable_unprepare(pdata->clk);
 205                 return PTR_ERR(pdata->rtc);
 206         }
 207
 208         /* HW does not support update faster than 1 seconds */
 209         pdata->rtc->uie_unsupported = 1;
 210
 211         return 0;
 212 }
 213
 214 static int xgene_rtc_remove(struct platform_device *pdev)
 215 {
 216         struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
 217
 218         xgene_rtc_alarm_irq_enable(&pdev->dev, 0);
 219         device_init_wakeup(&pdev->dev, 0);
 220         clk_disable_unprepare(pdata->clk);
 221         return 0;
 222 }
 223
 224 static int __maybe_unused xgene_rtc_suspend(struct device *dev)
 225 {
 226         struct platform_device *pdev = to_platform_device(dev);
 227         struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
 228         int irq;
 229
 230         irq = platform_get_irq(pdev, 0);
 231
 232         /*
 233          * If this RTC alarm will be used for waking the system up,
 234          * don't disable it of course. Else we just disable the alarm
 235          * and await suspension.
 236          */
 237         if (device_may_wakeup(&pdev->dev)) {
 238                 if (!enable_irq_wake(irq))
 239                         pdata->irq_wake = 1;
 240         } else {
 241                 pdata->irq_enabled = xgene_rtc_alarm_irq_enabled(dev);
 242                 xgene_rtc_alarm_irq_enable(dev, 0);
 243                 clk_disable_unprepare(pdata->clk);
 244         }
 245         return 0;
 246 }
 247
 248 static int __maybe_unused xgene_rtc_resume(struct device *dev)
 249 {
 250         struct platform_device *pdev = to_platform_device(dev);
 251         struct xgene_rtc_dev *pdata = platform_get_drvdata(pdev);
 252         int irq;
 253         int rc;
 254
 255         irq = platform_get_irq(pdev, 0);
 256
 257         if (device_may_wakeup(&pdev->dev)) {
 258                 if (pdata->irq_wake) {
 259                         disable_irq_wake(irq);
 260                         pdata->irq_wake = 0;
 261                 }
 262         } else {
 263                 rc = clk_prepare_enable(pdata->clk);
 264                 if (rc) {
 265                         dev_err(dev, "Unable to enable clock error %d\n", rc);
 266                         return rc;
 267                 }
 268                 xgene_rtc_alarm_irq_enable(dev, pdata->irq_enabled);
 269         }
 270
 271         return 0;
 272 }
 273
 274 static SIMPLE_DEV_PM_OPS(xgene_rtc_pm_ops, xgene_rtc_suspend, xgene_rtc_resume);
 275
 276 #ifdef CONFIG_OF
 277 static const struct of_device_id xgene_rtc_of_match[] = {
 278         {.compatible = "apm,xgene-rtc" },
 279         { }
 280 };
 281 MODULE_DEVICE_TABLE(of, xgene_rtc_of_match);
 282 #endif
 283
 284 static struct platform_driver xgene_rtc_driver = {
 285         .probe          = xgene_rtc_probe,
 286         .remove         = xgene_rtc_remove,
 287         .driver         = {
 288                 .name   = "xgene-rtc",
 289                 .pm = &xgene_rtc_pm_ops,
 290                 .of_match_table = of_match_ptr(xgene_rtc_of_match),
 291         },
 292 };
 293
 294 module_platform_driver(xgene_rtc_driver);
 295
 296 MODULE_DESCRIPTION("APM X-Gene SoC RTC driver");
 297 MODULE_AUTHOR("Rameshwar Sahu <rsahu@apm.com>");
 298 MODULE_LICENSE("GPL");