--- /dev/null
+/*
+ * PIC32 RTC driver
+ *
+ * Joshua Henderson <joshua.henderson@microchip.com>
+ * Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+
+#include <asm/mach-pic32/pic32.h>
+
+#define PIC32_RTCCON 0x00
+#define PIC32_RTCCON_ON BIT(15)
+#define PIC32_RTCCON_SIDL BIT(13)
+#define PIC32_RTCCON_RTCCLKSEL (3 << 9)
+#define PIC32_RTCCON_RTCCLKON BIT(6)
+#define PIC32_RTCCON_RTCWREN BIT(3)
+#define PIC32_RTCCON_RTCSYNC BIT(2)
+#define PIC32_RTCCON_HALFSEC BIT(1)
+#define PIC32_RTCCON_RTCOE BIT(0)
+
+#define PIC32_RTCALRM 0x10
+#define PIC32_RTCALRM_ALRMEN BIT(15)
+#define PIC32_RTCALRM_CHIME BIT(14)
+#define PIC32_RTCALRM_PIV BIT(13)
+#define PIC32_RTCALRM_ALARMSYNC BIT(12)
+#define PIC32_RTCALRM_AMASK 0x0F00
+#define PIC32_RTCALRM_ARPT 0xFF
+
+#define PIC32_RTCHOUR 0x23
+#define PIC32_RTCMIN 0x22
+#define PIC32_RTCSEC 0x21
+#define PIC32_RTCYEAR 0x33
+#define PIC32_RTCMON 0x32
+#define PIC32_RTCDAY 0x31
+
+#define PIC32_ALRMTIME 0x40
+#define PIC32_ALRMDATE 0x50
+
+#define PIC32_ALRMHOUR 0x43
+#define PIC32_ALRMMIN 0x42
+#define PIC32_ALRMSEC 0x41
+#define PIC32_ALRMYEAR 0x53
+#define PIC32_ALRMMON 0x52
+#define PIC32_ALRMDAY 0x51
+
+struct pic32_rtc_dev {
+ struct rtc_device *rtc;
+ void __iomem *reg_base;
+ struct clk *clk;
+ spinlock_t alarm_lock;
+ int alarm_irq;
+ bool alarm_clk_enabled;
+};
+
+static void pic32_rtc_alarm_clk_enable(struct pic32_rtc_dev *pdata,
+ bool enable)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&pdata->alarm_lock, flags);
+ if (enable) {
+ if (!pdata->alarm_clk_enabled) {
+ clk_enable(pdata->clk);
+ pdata->alarm_clk_enabled = true;
+ }
+ } else {
+ if (pdata->alarm_clk_enabled) {
+ clk_disable(pdata->clk);
+ pdata->alarm_clk_enabled = false;
+ }
+ }
+ spin_unlock_irqrestore(&pdata->alarm_lock, flags);
+}
+
+static irqreturn_t pic32_rtc_alarmirq(int irq, void *id)
+{
+ struct pic32_rtc_dev *pdata = (struct pic32_rtc_dev *)id;
+
+ clk_enable(pdata->clk);
+ rtc_update_irq(pdata->rtc, 1, RTC_AF | RTC_IRQF);
+ clk_disable(pdata->clk);
+
+ pic32_rtc_alarm_clk_enable(pdata, false);
+
+ return IRQ_HANDLED;
+}
+
+static int pic32_rtc_setaie(struct device *dev, unsigned int enabled)
+{
+ struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+ void __iomem *base = pdata->reg_base;
+
+ clk_enable(pdata->clk);
+
+ writel(PIC32_RTCALRM_ALRMEN,
+ base + (enabled ? PIC32_SET(PIC32_RTCALRM) :
+ PIC32_CLR(PIC32_RTCALRM)));
+
+ clk_disable(pdata->clk);
+
+ pic32_rtc_alarm_clk_enable(pdata, enabled);
+
+ return 0;
+}
+
+static int pic32_rtc_setfreq(struct device *dev, int freq)
+{
+ struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+ void __iomem *base = pdata->reg_base;
+
+ clk_enable(pdata->clk);
+
+ writel(PIC32_RTCALRM_AMASK, base + PIC32_CLR(PIC32_RTCALRM));
+ writel(freq << 8, base + PIC32_SET(PIC32_RTCALRM));
+ writel(PIC32_RTCALRM_CHIME, base + PIC32_SET(PIC32_RTCALRM));
+
+ clk_disable(pdata->clk);
+
+ return 0;
+}
+
+static int pic32_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
+{
+ struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+ void __iomem *base = pdata->reg_base;
+ unsigned int tries = 0;
+
+ clk_enable(pdata->clk);
+
+ do {
+ rtc_tm->tm_hour = readb(base + PIC32_RTCHOUR);
+ rtc_tm->tm_min = readb(base + PIC32_RTCMIN);
+ rtc_tm->tm_mon = readb(base + PIC32_RTCMON);
+ rtc_tm->tm_mday = readb(base + PIC32_RTCDAY);
+ rtc_tm->tm_year = readb(base + PIC32_RTCYEAR);
+ rtc_tm->tm_sec = readb(base + PIC32_RTCSEC);
+
+ /*
+ * The only way to work out whether the system was mid-update
+ * when we read it is to check the second counter, and if it
+ * is zero, then we re-try the entire read.
+ */
+ tries += 1;
+ } while (rtc_tm->tm_sec == 0 && tries < 2);
+
+ rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
+ rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
+ rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
+ rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
+ rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon) - 1;
+ rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
+
+ rtc_tm->tm_year += 100;
+
+ dev_dbg(dev, "read time %04d.%02d.%02d %02d:%02d:%02d\n",
+ 1900 + rtc_tm->tm_year, rtc_tm->tm_mon, rtc_tm->tm_mday,
+ rtc_tm->tm_hour, rtc_tm->tm_min, rtc_tm->tm_sec);
+
+ clk_disable(pdata->clk);
+ return rtc_valid_tm(rtc_tm);
+}
+
+static int pic32_rtc_settime(struct device *dev, struct rtc_time *tm)
+{
+ struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+ void __iomem *base = pdata->reg_base;
+ int year = tm->tm_year - 100;
+
+ dev_dbg(dev, "set time %04d.%02d.%02d %02d:%02d:%02d\n",
+ 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
+ tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+ if (year < 0 || year >= 100) {
+ dev_err(dev, "rtc only supports 100 years\n");
+ return -EINVAL;
+ }
+
+ clk_enable(pdata->clk);
+ writeb(bin2bcd(tm->tm_sec), base + PIC32_RTCSEC);
+ writeb(bin2bcd(tm->tm_min), base + PIC32_RTCMIN);
+ writeb(bin2bcd(tm->tm_hour), base + PIC32_RTCHOUR);
+ writeb(bin2bcd(tm->tm_mday), base + PIC32_RTCDAY);
+ writeb(bin2bcd(tm->tm_mon + 1), base + PIC32_RTCMON);
+ writeb(bin2bcd(year), base + PIC32_RTCYEAR);
+ clk_disable(pdata->clk);
+
+ return 0;
+}
+
+static int pic32_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+ struct rtc_time *alm_tm = &alrm->time;
+ void __iomem *base = pdata->reg_base;
+ unsigned int alm_en;
+
+ clk_enable(pdata->clk);
+ alm_tm->tm_sec = readb(base + PIC32_ALRMSEC);
+ alm_tm->tm_min = readb(base + PIC32_ALRMMIN);
+ alm_tm->tm_hour = readb(base + PIC32_ALRMHOUR);
+ alm_tm->tm_mon = readb(base + PIC32_ALRMMON);
+ alm_tm->tm_mday = readb(base + PIC32_ALRMDAY);
+ alm_tm->tm_year = readb(base + PIC32_ALRMYEAR);
+
+ alm_en = readb(base + PIC32_RTCALRM);
+
+ alrm->enabled = (alm_en & PIC32_RTCALRM_ALRMEN) ? 1 : 0;
+
+ dev_dbg(dev, "getalarm: %d, %04d.%02d.%02d %02d:%02d:%02d\n",
+ alm_en,
+ 1900 + alm_tm->tm_year, alm_tm->tm_mon, alm_tm->tm_mday,
+ alm_tm->tm_hour, alm_tm->tm_min, alm_tm->tm_sec);
+
+ alm_tm->tm_sec = bcd2bin(alm_tm->tm_sec);
+ alm_tm->tm_min = bcd2bin(alm_tm->tm_min);
+ alm_tm->tm_hour = bcd2bin(alm_tm->tm_hour);
+ alm_tm->tm_mday = bcd2bin(alm_tm->tm_mday);
+ alm_tm->tm_mon = bcd2bin(alm_tm->tm_mon) - 1;
+ alm_tm->tm_year = bcd2bin(alm_tm->tm_year);
+
+ clk_disable(pdata->clk);
+ return 0;
+}
+
+static int pic32_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+ struct rtc_time *tm = &alrm->time;
+ void __iomem *base = pdata->reg_base;
+
+ clk_enable(pdata->clk);
+ dev_dbg(dev, "setalarm: %d, %04d.%02d.%02d %02d:%02d:%02d\n",
+ alrm->enabled,
+ 1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
+ tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+ writel(0x00, base + PIC32_ALRMTIME);
+ writel(0x00, base + PIC32_ALRMDATE);
+
+ pic32_rtc_setaie(dev, alrm->enabled);
+
+ clk_disable(pdata->clk);
+ return 0;
+}
+
+static int pic32_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+ struct pic32_rtc_dev *pdata = dev_get_drvdata(dev);
+ void __iomem *base = pdata->reg_base;
+ unsigned int repeat;
+
+ clk_enable(pdata->clk);
+
+ repeat = readw(base + PIC32_RTCALRM);
+ repeat &= PIC32_RTCALRM_ARPT;
+ seq_printf(seq, "periodic_IRQ\t: %s\n", repeat ? "yes" : "no");
+
+ clk_disable(pdata->clk);
+ return 0;
+}
+
+static const struct rtc_class_ops pic32_rtcops = {
+ .read_time = pic32_rtc_gettime,
+ .set_time = pic32_rtc_settime,
+ .read_alarm = pic32_rtc_getalarm,
+ .set_alarm = pic32_rtc_setalarm,
+ .proc = pic32_rtc_proc,
+ .alarm_irq_enable = pic32_rtc_setaie,
+};
+
+static void pic32_rtc_enable(struct pic32_rtc_dev *pdata, int en)
+{
+ void __iomem *base = pdata->reg_base;
+
+ if (!base)
+ return;
+
+ clk_enable(pdata->clk);
+ if (!en) {
+ writel(PIC32_RTCCON_ON, base + PIC32_CLR(PIC32_RTCCON));
+ } else {
+ pic32_syskey_unlock();
+
+ writel(PIC32_RTCCON_RTCWREN, base + PIC32_SET(PIC32_RTCCON));
+ writel(3 << 9, base + PIC32_CLR(PIC32_RTCCON));
+
+ if (!(readl(base + PIC32_RTCCON) & PIC32_RTCCON_ON))
+ writel(PIC32_RTCCON_ON, base + PIC32_SET(PIC32_RTCCON));
+ }
+ clk_disable(pdata->clk);
+}
+
+static int pic32_rtc_remove(struct platform_device *pdev)
+{
+ struct pic32_rtc_dev *pdata = platform_get_drvdata(pdev);
+
+ pic32_rtc_setaie(&pdev->dev, 0);
+ clk_unprepare(pdata->clk);
+ pdata->clk = NULL;
+
+ return 0;
+}
+
+static int pic32_rtc_probe(struct platform_device *pdev)
+{
+ struct pic32_rtc_dev *pdata;
+ struct resource *res;
+ int ret;
+
+ pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+ if (!pdata)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, pdata);
+
+ pdata->alarm_irq = platform_get_irq(pdev, 0);
+ if (pdata->alarm_irq < 0) {
+ dev_err(&pdev->dev, "no irq for alarm\n");
+ return pdata->alarm_irq;
+ }
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ pdata->reg_base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(pdata->reg_base))
+ return PTR_ERR(pdata->reg_base);
+
+ pdata->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(pdata->clk)) {
+ dev_err(&pdev->dev, "failed to find rtc clock source\n");
+ ret = PTR_ERR(pdata->clk);
+ pdata->clk = NULL;
+ return ret;
+ }
+
+ spin_lock_init(&pdata->alarm_lock);
+
+ clk_prepare_enable(pdata->clk);
+
+ pic32_rtc_enable(pdata, 1);
+
+ device_init_wakeup(&pdev->dev, 1);
+
+ pdata->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
+ &pic32_rtcops,
+ THIS_MODULE);
+ if (IS_ERR(pdata->rtc)) {
+ ret = PTR_ERR(pdata->rtc);
+ goto err_nortc;
+ }
+
+ pdata->rtc->max_user_freq = 128;
+
+ pic32_rtc_setfreq(&pdev->dev, 1);
+ ret = devm_request_irq(&pdev->dev, pdata->alarm_irq,
+ pic32_rtc_alarmirq, 0,
+ dev_name(&pdev->dev), pdata);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "IRQ %d error %d\n", pdata->alarm_irq, ret);
+ goto err_nortc;
+ }
+
+ clk_disable(pdata->clk);
+
+ return 0;
+
+err_nortc:
+ pic32_rtc_enable(pdata, 0);
+ clk_disable_unprepare(pdata->clk);
+
+ return ret;
+}
+
+static const struct of_device_id pic32_rtc_dt_ids[] = {
+ { .compatible = "microchip,pic32mzda-rtc" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pic32_rtc_dt_ids);
+
+static struct platform_driver pic32_rtc_driver = {
+ .probe = pic32_rtc_probe,
+ .remove = pic32_rtc_remove,
+ .driver = {
+ .name = "pic32-rtc",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(pic32_rtc_dt_ids),
+ },
+};
+module_platform_driver(pic32_rtc_driver);
+
+MODULE_DESCRIPTION("Microchip PIC32 RTC Driver");
+MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
+MODULE_LICENSE("GPL");
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