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Subject[PATCH v2 2/2] rtc: Add Cadence RTC driver
Date
This patch adds a driver for Cadence RTC controller.

It can be enabled with RTC_DRV_CADENCE Kconfig option.
It supports waking system from sleep modes.

Signed-off-by: Jan Kotas <jank@cadence.com>
---
drivers/rtc/Kconfig | 10 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-cadence.c | 423 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 434 insertions(+)
create mode 100644 drivers/rtc/rtc-cadence.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 225b0b851..0aba341ad 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1508,6 +1508,16 @@ config RTC_DRV_ARMADA38X
This driver can also be built as a module. If so, the module
will be called armada38x-rtc.

+config RTC_DRV_CADENCE
+ tristate "Cadence RTC driver"
+ depends on OF && HAS_IOMEM
+ help
+ If you say Y here you will get access to Cadence RTC IP
+ found on certain SOCs.
+
+ To compile this driver as a module, choose M here: the
+ module will be called rtc-cadence.
+
config RTC_DRV_FTRTC010
tristate "Faraday Technology FTRTC010 RTC"
depends on HAS_IOMEM
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index df022d820..5adb41b45 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_RTC_DRV_AU1XXX) += rtc-au1xxx.o
obj-$(CONFIG_RTC_DRV_BQ32K) += rtc-bq32k.o
obj-$(CONFIG_RTC_DRV_BQ4802) += rtc-bq4802.o
obj-$(CONFIG_RTC_DRV_BRCMSTB) += rtc-brcmstb-waketimer.o
+obj-$(CONFIG_RTC_DRV_CADENCE) += rtc-cadence.o
obj-$(CONFIG_RTC_DRV_CMOS) += rtc-cmos.o
obj-$(CONFIG_RTC_DRV_COH901331) += rtc-coh901331.o
obj-$(CONFIG_RTC_DRV_CPCAP) += rtc-cpcap.o
diff --git a/drivers/rtc/rtc-cadence.c b/drivers/rtc/rtc-cadence.c
new file mode 100644
index 000000000..3b7d643c8
--- /dev/null
+++ b/drivers/rtc/rtc-cadence.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2019 Cadence
+ *
+ * Authors:
+ * Jan Kotas <jank@cadence.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/rtc.h>
+#include <linux/clk.h>
+#include <linux/bcd.h>
+#include <linux/bitfield.h>
+#include <linux/interrupt.h>
+#include <linux/pm_wakeirq.h>
+
+/* Registers */
+#define CDNS_RTC_CTLR 0x00
+#define CDNS_RTC_HMR 0x04
+#define CDNS_RTC_TIMR 0x08
+#define CDNS_RTC_CALR 0x0C
+#define CDNS_RTC_TIMAR 0x10
+#define CDNS_RTC_CALAR 0x14
+#define CDNS_RTC_AENR 0x18
+#define CDNS_RTC_EFLR 0x1C
+#define CDNS_RTC_IENR 0x20
+#define CDNS_RTC_IDISR 0x24
+#define CDNS_RTC_IMSKR 0x28
+#define CDNS_RTC_STSR 0x2C
+#define CDNS_RTC_KRTCR 0x30
+
+/* Control */
+#define CDNS_RTC_CTLR_TIME BIT(0)
+#define CDNS_RTC_CTLR_CAL BIT(1)
+#define CDNS_RTC_CTLR_TIME_CAL (CDNS_RTC_CTLR_TIME | CDNS_RTC_CTLR_CAL)
+
+/* Status */
+#define CDNS_RTC_STSR_VT BIT(0)
+#define CDNS_RTC_STSR_VC BIT(1)
+#define CDNS_RTC_STSR_VTA BIT(2)
+#define CDNS_RTC_STSR_VCA BIT(3)
+#define CDNS_RTC_STSR_VT_VC (CDNS_RTC_STSR_VT | CDNS_RTC_STSR_VC)
+#define CDNS_RTC_STSR_VTA_VCA (CDNS_RTC_STSR_VTA | CDNS_RTC_STSR_VCA)
+
+/* Keep RTC */
+#define CDNS_RTC_KRTCR_KRTC BIT(0)
+
+/* Alarm, Event, Interrupt */
+#define CDNS_RTC_AEI_HOS BIT(0)
+#define CDNS_RTC_AEI_SEC BIT(1)
+#define CDNS_RTC_AEI_MIN BIT(2)
+#define CDNS_RTC_AEI_HOUR BIT(3)
+#define CDNS_RTC_AEI_DATE BIT(4)
+#define CDNS_RTC_AEI_MNTH BIT(5)
+#define CDNS_RTC_AEI_ALRM BIT(6)
+
+/* Time */
+#define CDNS_RTC_TIME_H GENMASK(7, 0)
+#define CDNS_RTC_TIME_S GENMASK(14, 8)
+#define CDNS_RTC_TIME_M GENMASK(22, 16)
+#define CDNS_RTC_TIME_HR GENMASK(29, 24)
+#define CDNS_RTC_TIME_PM BIT(30)
+#define CDNS_RTC_TIME_CH BIT(31)
+
+/* Calendar */
+#define CDNS_RTC_CAL_DAY GENMASK(2, 0)
+#define CDNS_RTC_CAL_M GENMASK(7, 3)
+#define CDNS_RTC_CAL_D GENMASK(13, 8)
+#define CDNS_RTC_CAL_Y GENMASK(23, 16)
+#define CDNS_RTC_CAL_C GENMASK(29, 24)
+#define CDNS_RTC_CAL_CH BIT(31)
+
+#define CDNS_RTC_MAX_REGS_TRIES 3
+
+struct cdns_rtc {
+ struct rtc_device *rtc_dev;
+ struct clk *pclk;
+ struct clk *ref_clk;
+ void __iomem *regs;
+ int irq;
+};
+
+static void cdns_rtc_set_enabled(struct cdns_rtc *crtc, bool enabled)
+{
+ u32 reg = enabled ? 0x0 : CDNS_RTC_CTLR_TIME_CAL;
+
+ writel(reg, crtc->regs + CDNS_RTC_CTLR);
+}
+
+static bool cdns_rtc_get_enabled(struct cdns_rtc *crtc)
+{
+ return !(readl(crtc->regs + CDNS_RTC_CTLR) & CDNS_RTC_CTLR_TIME_CAL);
+}
+
+static irqreturn_t cdns_rtc_irq_handler(int irq, void *id)
+{
+ struct device *dev = id;
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+ /* Reading the register clears it */
+ if (!(readl(crtc->regs + CDNS_RTC_EFLR) & CDNS_RTC_AEI_ALRM))
+ return IRQ_NONE;
+
+ rtc_update_irq(crtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
+ return IRQ_HANDLED;
+}
+
+static u32 cdns_rtc_time2reg(struct rtc_time *tm)
+{
+ return FIELD_PREP(CDNS_RTC_TIME_S, bin2bcd(tm->tm_sec))
+ | FIELD_PREP(CDNS_RTC_TIME_M, bin2bcd(tm->tm_min))
+ | FIELD_PREP(CDNS_RTC_TIME_HR, bin2bcd(tm->tm_hour));
+}
+
+static void cdns_rtc_reg2time(u32 reg, struct rtc_time *tm)
+{
+ tm->tm_sec = bcd2bin(FIELD_GET(CDNS_RTC_TIME_S, reg));
+ tm->tm_min = bcd2bin(FIELD_GET(CDNS_RTC_TIME_M, reg));
+ tm->tm_hour = bcd2bin(FIELD_GET(CDNS_RTC_TIME_HR, reg));
+}
+
+static int cdns_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+ u32 reg;
+
+ /* If the RTC is disabled, assume the values are invalid */
+ if (!cdns_rtc_get_enabled(crtc))
+ return -EINVAL;
+
+ cdns_rtc_set_enabled(crtc, false);
+
+ reg = readl(crtc->regs + CDNS_RTC_TIMR);
+ cdns_rtc_reg2time(reg, tm);
+
+ reg = readl(crtc->regs + CDNS_RTC_CALR);
+ tm->tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
+ tm->tm_mon = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
+ tm->tm_year = bcd2bin(FIELD_GET(CDNS_RTC_CAL_Y, reg))
+ + bcd2bin(FIELD_GET(CDNS_RTC_CAL_C, reg)) * 100 - 1900;
+ tm->tm_wday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_DAY, reg)) - 1;
+
+ cdns_rtc_set_enabled(crtc, true);
+ return 0;
+}
+
+static int cdns_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+ u32 timr, calr, stsr;
+ int ret = -EIO;
+ int year = tm->tm_year + 1900;
+ int tries;
+
+ cdns_rtc_set_enabled(crtc, false);
+
+ timr = cdns_rtc_time2reg(tm);
+
+ calr = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(tm->tm_mday))
+ | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(tm->tm_mon + 1))
+ | FIELD_PREP(CDNS_RTC_CAL_Y, bin2bcd(year % 100))
+ | FIELD_PREP(CDNS_RTC_CAL_C, bin2bcd(year / 100))
+ | FIELD_PREP(CDNS_RTC_CAL_DAY, tm->tm_wday + 1);
+
+ /* Update registers, check valid flags */
+ for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
+ writel(timr, crtc->regs + CDNS_RTC_TIMR);
+ writel(calr, crtc->regs + CDNS_RTC_CALR);
+ stsr = readl(crtc->regs + CDNS_RTC_STSR);
+
+ if ((stsr & CDNS_RTC_STSR_VT_VC) == CDNS_RTC_STSR_VT_VC) {
+ ret = 0;
+ break;
+ }
+ }
+
+ cdns_rtc_set_enabled(crtc, true);
+ return ret;
+}
+
+static int cdns_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+ if (enabled) {
+ writel((CDNS_RTC_AEI_SEC | CDNS_RTC_AEI_MIN | CDNS_RTC_AEI_HOUR
+ | CDNS_RTC_AEI_DATE | CDNS_RTC_AEI_MNTH),
+ crtc->regs + CDNS_RTC_AENR);
+ writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IENR);
+ } else {
+ writel(0, crtc->regs + CDNS_RTC_AENR);
+ writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IDISR);
+ }
+
+ return 0;
+}
+
+static int cdns_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+ u32 reg;
+
+ reg = readl(crtc->regs + CDNS_RTC_TIMAR);
+ cdns_rtc_reg2time(reg, &alarm->time);
+
+ reg = readl(crtc->regs + CDNS_RTC_CALAR);
+ alarm->time.tm_mday = bcd2bin(FIELD_GET(CDNS_RTC_CAL_D, reg));
+ alarm->time.tm_mon = bcd2bin(FIELD_GET(CDNS_RTC_CAL_M, reg)) - 1;
+
+ return 0;
+}
+
+static int cdns_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+ int ret = -EIO;
+ int tries;
+ u32 timar, calar, stsr;
+
+ cdns_rtc_alarm_irq_enable(dev, 0);
+
+ timar = cdns_rtc_time2reg(&alarm->time);
+ calar = FIELD_PREP(CDNS_RTC_CAL_D, bin2bcd(alarm->time.tm_mday))
+ | FIELD_PREP(CDNS_RTC_CAL_M, bin2bcd(alarm->time.tm_mon + 1));
+
+ /* Update registers, check valid alarm flags */
+ for (tries = 0; tries < CDNS_RTC_MAX_REGS_TRIES; tries++) {
+ writel(timar, crtc->regs + CDNS_RTC_TIMAR);
+ writel(calar, crtc->regs + CDNS_RTC_CALAR);
+ stsr = readl(crtc->regs + CDNS_RTC_STSR);
+
+ if ((stsr & CDNS_RTC_STSR_VTA_VCA) == CDNS_RTC_STSR_VTA_VCA) {
+ ret = 0;
+ break;
+ }
+ }
+
+ if (!ret)
+ cdns_rtc_alarm_irq_enable(dev, alarm->enabled);
+ return ret;
+}
+
+static const struct rtc_class_ops cdns_rtc_ops = {
+ .read_time = cdns_rtc_read_time,
+ .set_time = cdns_rtc_set_time,
+ .read_alarm = cdns_rtc_read_alarm,
+ .set_alarm = cdns_rtc_set_alarm,
+ .alarm_irq_enable = cdns_rtc_alarm_irq_enable,
+};
+
+static int cdns_rtc_probe(struct platform_device *pdev)
+{
+ struct cdns_rtc *crtc;
+ struct resource *res;
+ int ret;
+ unsigned long ref_clk_freq;
+
+ crtc = devm_kzalloc(&pdev->dev, sizeof(*crtc), GFP_KERNEL);
+ if (!crtc)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ crtc->regs = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(crtc->regs))
+ return PTR_ERR(crtc->regs);
+
+ crtc->irq = platform_get_irq(pdev, 0);
+ if (crtc->irq < 0)
+ return -EINVAL;
+
+ crtc->pclk = devm_clk_get(&pdev->dev, "pclk");
+ if (IS_ERR(crtc->pclk)) {
+ ret = PTR_ERR(crtc->pclk);
+ dev_err(&pdev->dev,
+ "Failed to retrieve the peripheral clock, %d\n", ret);
+ return ret;
+ }
+
+ crtc->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
+ if (IS_ERR(crtc->ref_clk)) {
+ ret = PTR_ERR(crtc->ref_clk);
+ dev_err(&pdev->dev,
+ "Failed to retrieve the reference clock, %d\n", ret);
+ return ret;
+ }
+
+ crtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(crtc->rtc_dev)) {
+ ret = PTR_ERR(crtc->rtc_dev);
+ dev_err(&pdev->dev,
+ "Failed to allocate the RTC device, %d\n", ret);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, crtc);
+
+ ret = clk_prepare_enable(crtc->pclk);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Failed to enable the peripheral clock, %d\n", ret);
+ return ret;
+ }
+
+ ret = clk_prepare_enable(crtc->ref_clk);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Failed to enable the reference clock, %d\n", ret);
+ goto err_disable_pclk;
+ }
+
+ ref_clk_freq = clk_get_rate(crtc->ref_clk);
+ if ((ref_clk_freq != 1) && (ref_clk_freq != 100)) {
+ dev_err(&pdev->dev,
+ "Invalid reference clock frequency %lu Hz.\n",
+ ref_clk_freq);
+ ret = -EINVAL;
+ goto err_disable_ref_clk;
+ }
+
+ ret = devm_request_irq(&pdev->dev, crtc->irq,
+ cdns_rtc_irq_handler, 0,
+ dev_name(&pdev->dev), &pdev->dev);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Failed to request interrupt for the device, %d\n",
+ ret);
+ goto err_disable_ref_clk;
+ }
+
+ /* The RTC supports 01.01.1900 - 31.12.2999 */
+ crtc->rtc_dev->range_min = mktime64(1900, 1, 1, 0, 0, 0);
+ crtc->rtc_dev->range_max = mktime64(2999, 12, 31, 23, 59, 59);
+
+ crtc->rtc_dev->ops = &cdns_rtc_ops;
+ device_init_wakeup(&pdev->dev, true);
+
+ /* Always use 24-hour mode and keep the RTC values */
+ writel(0, crtc->regs + CDNS_RTC_HMR);
+ writel(CDNS_RTC_KRTCR_KRTC, crtc->regs + CDNS_RTC_KRTCR);
+
+ ret = rtc_register_device(crtc->rtc_dev);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "Failed to register the RTC device, %d\n", ret);
+ goto err_disable_wakeup;
+ }
+
+ return 0;
+
+err_disable_wakeup:
+ device_init_wakeup(&pdev->dev, false);
+
+err_disable_ref_clk:
+ clk_disable_unprepare(crtc->ref_clk);
+
+err_disable_pclk:
+ clk_disable_unprepare(crtc->pclk);
+
+ return ret;
+}
+
+static int cdns_rtc_remove(struct platform_device *pdev)
+{
+ struct cdns_rtc *crtc = platform_get_drvdata(pdev);
+
+ cdns_rtc_alarm_irq_enable(&pdev->dev, 0);
+ device_init_wakeup(&pdev->dev, 0);
+
+ clk_disable_unprepare(crtc->pclk);
+ clk_disable_unprepare(crtc->ref_clk);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int cdns_rtc_suspend(struct device *dev)
+{
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ enable_irq_wake(crtc->irq);
+
+ return 0;
+}
+
+static int cdns_rtc_resume(struct device *dev)
+{
+ struct cdns_rtc *crtc = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ disable_irq_wake(crtc->irq);
+
+ return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(cdns_rtc_pm_ops, cdns_rtc_suspend, cdns_rtc_resume);
+
+static const struct of_device_id cdns_rtc_of_match[] = {
+ { .compatible = "cdns,rtc-r109v3" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, cdns_rtc_of_match);
+
+static struct platform_driver cdns_rtc_driver = {
+ .driver = {
+ .name = "cdns-rtc",
+ .of_match_table = cdns_rtc_of_match,
+ .pm = &cdns_rtc_pm_ops,
+ },
+ .probe = cdns_rtc_probe,
+ .remove = cdns_rtc_remove,
+};
+module_platform_driver(cdns_rtc_driver);
+
+MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
+MODULE_DESCRIPTION("Cadence RTC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:cdns-rtc");
--
2.15.0
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