[PATCH 1/2] rtc: add rtc-lpc24xx driver
Joachim Eastwood
manabian at gmail.com
Thu May 14 10:34:34 PDT 2015
Add driver for the RTC found on NXP LPC24xx/178x/18xx/43xx devices.
The RTC provides calendar and clock functionality together with
periodic tick and alarm interrupt support.
Signed-off-by: Joachim Eastwood <manabian at gmail.com>
---
drivers/rtc/Kconfig | 11 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-lpc24xx.c | 379 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 391 insertions(+)
create mode 100644 drivers/rtc/rtc-lpc24xx.c
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6149ae01e11f..42b890716b1c 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1427,6 +1427,17 @@ config RTC_DRV_JZ4740
This driver can also be buillt as a module. If so, the module
will be called rtc-jz4740.
+config RTC_DRV_LPC24XX
+ depends on OF && (ARCH_LPC18XX || TEST_COMPILE)
+ tristate "NXP LPC2K RTC"
+ help
+ This enables support for the NXP RTC found which can be found on
+ LPC24xx/178x/18xx/43xx devices.
+
+ If you have one of the devices above enable this driver to use
+ the hardware RTC. This driver can also be buillt as a module. If
+ so, the module will be called rtc-lpc24xx.
+
config RTC_DRV_LPC32XX
depends on ARCH_LPC32XX
tristate "NXP LPC32XX RTC"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index c31731c29762..8687a2e13247 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -73,6 +73,7 @@ obj-$(CONFIG_RTC_DRV_ISL12022) += rtc-isl12022.o
obj-$(CONFIG_RTC_DRV_ISL12057) += rtc-isl12057.o
obj-$(CONFIG_RTC_DRV_JZ4740) += rtc-jz4740.o
obj-$(CONFIG_RTC_DRV_LP8788) += rtc-lp8788.o
+obj-$(CONFIG_RTC_DRV_LPC24XX) += rtc-lpc24xx.o
obj-$(CONFIG_RTC_DRV_LPC32XX) += rtc-lpc32xx.o
obj-$(CONFIG_RTC_DRV_LOONGSON1) += rtc-ls1x.o
obj-$(CONFIG_RTC_DRV_M41T80) += rtc-m41t80.o
diff --git a/drivers/rtc/rtc-lpc24xx.c b/drivers/rtc/rtc-lpc24xx.c
new file mode 100644
index 000000000000..ffa6e568b308
--- /dev/null
+++ b/drivers/rtc/rtc-lpc24xx.c
@@ -0,0 +1,379 @@
+/*
+ * Driver for NXP LPC24xx/178x/18xx/43xx Real-Time Clock (RTC)
+ *
+ * Copyright (C) 2011 NXP Semiconductors
+ * Copyright (C) 2015 Joachim Eastwood <manabian at gmail.com>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+/* LPC24xx RTC register offsets */
+#define LPC24XX_ILR 0x00
+#define LPC24XX_CTC 0x04
+#define LPC24XX_CCR 0x08
+#define LPC24XX_CIIR 0x0c
+#define LPC24XX_AMR 0x10
+#define LPC24XX_CTIME0 0x14
+#define LPC24XX_CTIME1 0x18
+#define LPC24XX_CTIME2 0x1c
+#define LPC24XX_SEC 0x20
+#define LPC24XX_MIN 0x24
+#define LPC24XX_HOUR 0x28
+#define LPC24XX_DOM 0x2c
+#define LPC24XX_DOW 0x30
+#define LPC24XX_DOY 0x34
+#define LPC24XX_MONTH 0x38
+#define LPC24XX_YEAR 0x3c
+#define LPC24XX_CISS 0x40 /* LPC24xx only */
+#define LPC178X_CALIBRATION 0x40 /* LPC178x and up */
+#define LPC24XX_ALSEC 0x60
+#define LPC24XX_ALMIN 0x64
+#define LPC24XX_ALHOUR 0x68
+#define LPC24XX_ALDOM 0x6c
+#define LPC24XX_ALDOW 0x70
+#define LPC24XX_ALDOY 0x74
+#define LPC24XX_ALMON 0x78
+#define LPC24XX_ALYEAR 0x7c
+#define LPC24XX_PREINT 0x80 /* LPC24xx only */
+#define LPC24XX_PREFRAC 0x84 /* LPC24xx only */
+
+#define LPC24XX_RTCCIF BIT(0)
+#define LPC24XX_RTCALF BIT(1)
+#define LPC24XX_RTSSF BIT(2) /* LPC24xx only */
+
+#define LPC24XX_CLKEN BIT(0)
+#define LPC24XX_CTCRST BIT(1)
+#define LPC24XX_CLKSRC BIT(4) /* LPC24xx only */
+#define LPC178X_CCALEN BIT(4) /* LPC178x and up */
+
+#define LPC24XX_IMSEC BIT(0)
+#define LPC24XX_IMMIN BIT(1)
+#define LPC24XX_IMHOUR BIT(2)
+#define LPC24XX_IMDOM BIT(3)
+#define LPC24XX_IMDOW BIT(4)
+#define LPC24XX_IMDOY BIT(5)
+#define LPC24XX_IMMON BIT(6)
+#define LPC24XX_IMYEAR BIT(7)
+
+#define LPC24XX_ALARM_DISABLE 0xff
+
+#define CT0_SECS(x) (((x) >> 0) & 0x3f)
+#define CT0_MINS(x) (((x) >> 8) & 0x3f)
+#define CT0_HOURS(x) (((x) >> 16) & 0x1f)
+#define CT0_DOW(x) (((x) >> 24) & 0x07)
+#define CT1_DOM(x) (((x) >> 0) & 0x1f)
+#define CT1_MONTH(x) (((x) >> 8) & 0x0f)
+#define CT1_YEAR(x) (((x) >> 16) & 0xfff)
+#define CT2_DOY(x) (((x) >> 0) & 0xfff)
+
+#define rtc_readl(dev, reg) readl((dev)->rtc_base + (reg))
+#define rtc_writel(dev, reg, val) writel((val), (dev)->rtc_base + (reg))
+
+/* lpc2k-rtc driver feature flags */
+#define HAVE_SUBSECOND BIT(0)
+#define HAVE_CALIBRATION BIT(1)
+#define HAVE_PRESCALER BIT(2)
+
+struct lpc24xx_rtc {
+ void __iomem *rtc_base;
+ struct rtc_device *rtc;
+ struct clk *clk_rtc;
+ struct clk *clk_reg;
+ u32 features;
+};
+
+static int lpc24xx_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+ u32 rtc_ctrl;
+
+ /* Disable RTC during update */
+ rtc_ctrl = rtc_readl(rtc, LPC24XX_CCR);
+ rtc_writel(rtc, LPC24XX_CCR, rtc_ctrl & ~LPC24XX_CLKEN);
+
+ rtc_writel(rtc, LPC24XX_SEC, tm->tm_sec);
+ rtc_writel(rtc, LPC24XX_MIN, tm->tm_min);
+ rtc_writel(rtc, LPC24XX_HOUR, tm->tm_hour);
+ rtc_writel(rtc, LPC24XX_DOW, tm->tm_wday);
+ rtc_writel(rtc, LPC24XX_DOM, tm->tm_mday);
+ rtc_writel(rtc, LPC24XX_DOY, tm->tm_yday);
+ rtc_writel(rtc, LPC24XX_MONTH, tm->tm_mon);
+ rtc_writel(rtc, LPC24XX_YEAR, tm->tm_year);
+
+ rtc_writel(rtc, LPC24XX_CCR, rtc_ctrl | LPC24XX_CLKEN);
+
+ return 0;
+}
+
+static int lpc24xx_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+ u32 ct0, ct1, ct2;
+
+ ct0 = rtc_readl(rtc, LPC24XX_CTIME0);
+ ct1 = rtc_readl(rtc, LPC24XX_CTIME1);
+ ct2 = rtc_readl(rtc, LPC24XX_CTIME2);
+
+ tm->tm_sec = CT0_SECS(ct0);
+ tm->tm_min = CT0_MINS(ct0);
+ tm->tm_hour = CT0_HOURS(ct0);
+ tm->tm_wday = CT0_DOW(ct0);
+ tm->tm_mon = CT1_MONTH(ct1);
+ tm->tm_mday = CT1_DOM(ct1);
+ tm->tm_year = CT1_YEAR(ct1);
+ tm->tm_yday = CT2_DOY(ct2);
+
+ if (rtc_valid_tm(tm) < 0) {
+ dev_warn(dev, "retrieved date and time is invalid\n");
+ rtc_time64_to_tm(0, tm);
+ lpc24xx_rtc_set_time(dev, tm);
+ }
+
+ return 0;
+}
+
+static int lpc24xx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+ struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+ struct rtc_time *tm = &wkalrm->time;
+
+ tm->tm_sec = rtc_readl(rtc, LPC24XX_ALSEC);
+ tm->tm_min = rtc_readl(rtc, LPC24XX_ALMIN);
+ tm->tm_hour = rtc_readl(rtc, LPC24XX_ALHOUR);
+ tm->tm_mday = rtc_readl(rtc, LPC24XX_ALDOM);
+ tm->tm_wday = rtc_readl(rtc, LPC24XX_ALDOW);
+ tm->tm_yday = rtc_readl(rtc, LPC24XX_ALDOY);
+ tm->tm_mon = rtc_readl(rtc, LPC24XX_ALMON);
+ tm->tm_year = rtc_readl(rtc, LPC24XX_ALYEAR);
+
+ wkalrm->enabled = rtc_readl(rtc, LPC24XX_AMR) == 0;
+ wkalrm->pending = !!(rtc_readl(rtc, LPC24XX_ILR) & LPC24XX_RTCCIF);
+
+ return rtc_valid_tm(&wkalrm->time);
+}
+
+static int lpc24xx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+ struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+ struct rtc_time *tm = &wkalrm->time;
+
+ /* Disable alarm IRQs during update */
+ rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+
+ rtc_writel(rtc, LPC24XX_ALSEC, tm->tm_sec);
+ rtc_writel(rtc, LPC24XX_ALMIN, tm->tm_min);
+ rtc_writel(rtc, LPC24XX_ALHOUR, tm->tm_hour);
+ rtc_writel(rtc, LPC24XX_ALDOM, tm->tm_mday);
+ rtc_writel(rtc, LPC24XX_ALDOW, tm->tm_wday);
+ rtc_writel(rtc, LPC24XX_ALDOY, tm->tm_yday);
+ rtc_writel(rtc, LPC24XX_ALMON, tm->tm_mon);
+ rtc_writel(rtc, LPC24XX_ALYEAR, tm->tm_year);
+
+ if (wkalrm->enabled)
+ rtc_writel(rtc, LPC24XX_AMR, 0);
+
+ return 0;
+}
+
+static int lpc24xx_rtc_alarm_irq_enable(struct device *dev,
+ unsigned int enabled)
+{
+ struct lpc24xx_rtc *rtc = dev_get_drvdata(dev);
+
+ if (enabled)
+ rtc_writel(rtc, LPC24XX_AMR, 0);
+ else
+ rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+
+ return 0;
+}
+
+static irqreturn_t lpc24xx_rtc_interrupt(int irq, void *dev)
+{
+ unsigned long events = RTC_IRQF;
+ struct lpc24xx_rtc *rtc = dev;
+ u32 rtc_iir;
+
+ /* Check interrupt cause */
+ rtc_iir = rtc_readl(rtc, LPC24XX_ILR);
+
+ /* 1s tick */
+ if (rtc_iir & LPC24XX_RTCCIF)
+ events |= RTC_UF;
+
+ /* Alarm */
+ if (rtc_iir & LPC24XX_RTCALF) {
+ events |= RTC_AF;
+ rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+ }
+
+ /* Clear interrupt status and report event */
+ rtc_writel(rtc, LPC24XX_ILR, rtc_iir);
+ rtc_update_irq(rtc->rtc, 1, events);
+
+ return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops lpc24xx_rtc_ops = {
+ .read_time = lpc24xx_rtc_read_time,
+ .set_time = lpc24xx_rtc_set_time,
+ .read_alarm = lpc24xx_rtc_read_alarm,
+ .set_alarm = lpc24xx_rtc_set_alarm,
+ .alarm_irq_enable = lpc24xx_rtc_alarm_irq_enable,
+};
+
+static const struct of_device_id lpc24xx_rtc_match[] = {
+ { .compatible = "nxp,lpc1788-rtc", .data = (void *)HAVE_CALIBRATION},
+ { }
+};
+MODULE_DEVICE_TABLE(of, lpc24xx_rtc_match);
+
+static int lpc24xx_rtc_probe(struct platform_device *pdev)
+{
+ const struct of_device_id *match;
+ struct lpc24xx_rtc *rtc;
+ struct resource *res;
+ u32 rtc_ccr = 0;
+ int irq, ret;
+
+ match = of_match_device(lpc24xx_rtc_match, &pdev->dev);
+ if (!match) {
+ dev_err(&pdev->dev, "no device match found\n");
+ return -ENODEV;
+ }
+
+ rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+ if (!rtc)
+ return -ENOMEM;
+
+ rtc->features = (u32)match->data;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ rtc->rtc_base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(rtc->rtc_base))
+ return PTR_ERR(rtc->rtc_base);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_warn(&pdev->dev, "can't get interrupt resource\n");
+ return irq;
+ }
+
+ rtc->clk_rtc = devm_clk_get(&pdev->dev, "rtc");
+ if (IS_ERR(rtc->clk_rtc)) {
+ dev_err(&pdev->dev, "error getting rtc clock\n");
+ return PTR_ERR(rtc->clk_rtc);
+ }
+
+ rtc->clk_reg = devm_clk_get(&pdev->dev, "reg");
+ if (IS_ERR(rtc->clk_reg)) {
+ dev_err(&pdev->dev, "error getting reg clock\n");
+ return PTR_ERR(rtc->clk_reg);
+ }
+
+ ret = clk_prepare_enable(rtc->clk_rtc);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable rtc clock\n");
+ return ret;
+ }
+
+ ret = clk_prepare_enable(rtc->clk_reg);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable reg clock\n");
+ goto disable_rtc_clk;
+ }
+
+ platform_set_drvdata(pdev, rtc);
+
+ /* Clear the counter increment state */
+ rtc_writel(rtc, LPC24XX_ILR, LPC24XX_RTCCIF);
+
+ if (rtc->features & HAVE_PRESCALER) {
+ /* Clock source is 32k oscillator */
+ rtc_ccr = LPC24XX_CLKSRC;
+ rtc_writel(rtc, LPC24XX_CCR, rtc_ccr);
+
+ /* Set prescaler to divide by 1 */
+ rtc_writel(rtc, LPC24XX_PREINT, 0);
+ rtc_writel(rtc, LPC24XX_PREFRAC, 0);
+ }
+
+ if (rtc->features & HAVE_SUBSECOND) {
+ /* Disable sub-second interrupt */
+ rtc_writel(rtc, LPC24XX_CISS, 0);
+ }
+
+ /* Only 1-second interrupt will generate interrupt */
+ rtc_writel(rtc, LPC24XX_CIIR, LPC24XX_IMSEC);
+
+ /* Enable RTC count */
+ rtc_writel(rtc, LPC24XX_CCR, rtc_ccr | LPC24XX_CLKEN);
+
+ ret = devm_request_irq(&pdev->dev, irq, lpc24xx_rtc_interrupt, 0,
+ pdev->name, rtc);
+ if (ret < 0) {
+ dev_warn(&pdev->dev, "can't request interrupt\n");
+ goto disable_clks;
+ }
+
+ rtc->rtc = devm_rtc_device_register(&pdev->dev, "lpc2k-rtc",
+ &lpc24xx_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc->rtc)) {
+ dev_err(&pdev->dev, "can't register rtc device\n");
+ ret = PTR_ERR(rtc->rtc);
+ goto disable_clks;
+ }
+
+ return 0;
+
+disable_clks:
+ clk_disable_unprepare(rtc->clk_reg);
+disable_rtc_clk:
+ clk_disable_unprepare(rtc->clk_rtc);
+ return ret;
+}
+
+static int lpc24xx_rtc_remove(struct platform_device *pdev)
+{
+ struct lpc24xx_rtc *rtc = platform_get_drvdata(pdev);
+
+ /*
+ * Disable alarm, but leave RTC enabled so it
+ * remains valid across reset cycles.
+ */
+ rtc_writel(rtc, LPC24XX_AMR, LPC24XX_ALARM_DISABLE);
+ rtc_writel(rtc, LPC24XX_CCR, 0);
+
+ clk_disable_unprepare(rtc->clk_rtc);
+ clk_disable_unprepare(rtc->clk_reg);
+
+ return 0;
+}
+
+static struct platform_driver lpc24xx_rtc_driver = {
+ .probe = lpc24xx_rtc_probe,
+ .remove = lpc24xx_rtc_remove,
+ .driver = {
+ .name = "lpc2k-rtc",
+ .of_match_table = lpc24xx_rtc_match,
+ },
+};
+module_platform_driver(lpc24xx_rtc_driver);
+
+MODULE_AUTHOR("Kevin Wells <wellsk40 at gmail.com");
+MODULE_DESCRIPTION("RTC driver for the LPC24xx SoC");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:lpc2k-rtc");
--
1.8.0
More information about the linux-arm-kernel
mailing list