[PATCH v2 5/5] rtc: add mxc driver for i.MX53 SRTC
From: linux-kernel-dev
Date: Tue Dec 05 2017 - 09:09:11 EST
From: Patrick Bruenn <p.bruenn@xxxxxxxxxxxx>
Neither rtc-imxdi, rtc-mxc nor rtc-snvs are compatible with i.MX53.
This is driver enables support for the low power domain SRTC features:
- 32-bit MSB of non-rollover time counter
- 32-bit alarm register
Based on:
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/drivers/rtc/rtc-mxc_v2.c?h=imx_2.6.35_11.09.01
Signed-off-by: Patrick Bruenn <p.bruenn@xxxxxxxxxxxx>
---
v2:
- have seperate patches for dt-binding, CONFIG option, imx53.dtsi and driver
- add SPDX-License-Identifier and cleanup copyright notice
- replace __raw_readl/writel() with readl/writel()
- fix PM_SLEEP callbacks
- add CONFIG_RTC_DRV_MXC_V2 to build rtc-mxc_v2.c
- remove misleading or obvious comments and fix style of the remaining
- avoid endless loop while waiting for hw
- implement consistent locking; make spinlock a member of dev struct
- enable clk only for register accesses
- remove all udelay() calls since they are obsolete or redundant
(we are already waiting for register flags to change)
- init platform_data before registering irq callback
- let set_time() fail, when 32 bit rtc counter exceeded
- make names more consistent
- cleanup and reorder includes
- cleanup and remove unused defines
To: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
To: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx> (maintainer:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS)
Cc: linux-rtc@xxxxxxxxxxxxxxx (open list:REAL TIME CLOCK (RTC) SUBSYSTEM)
Cc: devicetree@xxxxxxxxxxxxxxx (open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS)
Cc: linux-kernel@xxxxxxxxxxxxxxx (open list)
Cc: Fabio Estevam <fabio.estevam@xxxxxxx>
Cc: Juergen Borleis <jbe@xxxxxxxxxxxxxx>
Cc: Noel Vellemans <Noel.Vellemans@xxxxxxxxxxxxx>
Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
Cc: Sascha Hauer <kernel@xxxxxxxxxxxxxx> (maintainer:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE)
Cc: Russell King <linux@xxxxxxxxxxxxxxx> (maintainer:ARM PORT)
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE)
Cc: Philippe Ombredanne <pombredanne@xxxxxxxx>
Cc: Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-mxc_v2.c | 433 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 434 insertions(+)
create mode 100644 drivers/rtc/rtc-mxc_v2.c
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index f2f50c11dc38..dcf60e61ae5c 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -106,6 +106,7 @@ obj-$(CONFIG_RTC_DRV_MT6397) += rtc-mt6397.o
obj-$(CONFIG_RTC_DRV_MT7622) += rtc-mt7622.o
obj-$(CONFIG_RTC_DRV_MV) += rtc-mv.o
obj-$(CONFIG_RTC_DRV_MXC) += rtc-mxc.o
+obj-$(CONFIG_RTC_DRV_MXC_V2) += rtc-mxc_v2.o
obj-$(CONFIG_RTC_DRV_NUC900) += rtc-nuc900.o
obj-$(CONFIG_RTC_DRV_OMAP) += rtc-omap.o
obj-$(CONFIG_RTC_DRV_OPAL) += rtc-opal.o
diff --git a/drivers/rtc/rtc-mxc_v2.c b/drivers/rtc/rtc-mxc_v2.c
new file mode 100644
index 000000000000..c5a6d2c293bb
--- /dev/null
+++ b/drivers/rtc/rtc-mxc_v2.c
@@ -0,0 +1,433 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Real Time Clock (RTC) Driver for i.MX53
+ * Copyright (c) 2004-2011 Freescale Semiconductor, Inc.
+ * Copyright (c) 2017 Beckhoff Automation GmbH & Co. KG
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#define SRTC_LPPDR_INIT 0x41736166 /* init for glitch detect */
+
+#define SRTC_LPCR_EN_LP BIT(3) /* lp enable */
+#define SRTC_LPCR_WAE BIT(4) /* lp wakeup alarm enable */
+#define SRTC_LPCR_ALP BIT(7) /* lp alarm flag */
+#define SRTC_LPCR_NSA BIT(11) /* lp non secure access */
+#define SRTC_LPCR_NVE BIT(14) /* lp non valid state exit bit */
+#define SRTC_LPCR_IE BIT(15) /* lp init state exit bit */
+
+#define SRTC_LPSR_ALP BIT(3) /* lp alarm flag */
+#define SRTC_LPSR_NVES BIT(14) /* lp non-valid state exit status */
+#define SRTC_LPSR_IES BIT(15) /* lp init state exit status */
+
+#define SRTC_LPSCMR 0x00 /* LP Secure Counter MSB Reg */
+#define SRTC_LPSCLR 0x04 /* LP Secure Counter LSB Reg */
+#define SRTC_LPSAR 0x08 /* LP Secure Alarm Reg */
+#define SRTC_LPCR 0x10 /* LP Control Reg */
+#define SRTC_LPSR 0x14 /* LP Status Reg */
+#define SRTC_LPPDR 0x18 /* LP Power Supply Glitch Detector Reg */
+
+/* max. number of retries to read registers, 120 was max during test */
+#define REG_READ_TIMEOUT 2000
+
+struct mxc_rtc_data {
+ struct rtc_device *rtc;
+ void __iomem *ioaddr;
+ struct clk *clk;
+ spinlock_t lock; /* protects register access */
+ int irq;
+};
+
+/*
+ * This function does write synchronization for writes to the lp srtc block.
+ * To take care of the asynchronous CKIL clock, all writes from the IP domain
+ * will be synchronized to the CKIL domain.
+ * The caller should hold the pdata->lock
+ */
+static inline void mxc_rtc_sync_lp_locked(void __iomem *ioaddr)
+{
+ unsigned int i;
+
+ /* Wait for 3 CKIL cycles */
+ for (i = 0; i < 3; i++) {
+ const u32 count = readl(ioaddr + SRTC_LPSCLR);
+ unsigned int timeout = REG_READ_TIMEOUT;
+
+ while ((readl(ioaddr + SRTC_LPSCLR)) == count) {
+ if (!--timeout) {
+ pr_err("SRTC_LPSCLR stuck! Check your hw.\n");
+ return;
+ }
+ }
+ }
+}
+
+/*
+ * This function updates the RTC alarm registers and then clears all the
+ * interrupt status bits.
+ * The caller should hold the pdata->lock
+ *
+ * @param alrm the new alarm value to be updated in the RTC
+ *
+ * @return 0 if successful; non-zero otherwise.
+ */
+static int mxc_rtc_write_alarm_locked(struct mxc_rtc_data *const pdata,
+ struct rtc_time *alarm_tm)
+{
+ void __iomem *const ioaddr = pdata->ioaddr;
+ unsigned long time;
+
+ rtc_tm_to_time(alarm_tm, &time);
+
+ if (time > U32_MAX) {
+ pr_err("Hopefully I am out of service by then :-(\n");
+ return -EINVAL;
+ }
+
+ writel((u32)time, ioaddr + SRTC_LPSAR);
+
+ /* clear alarm interrupt status bit */
+ writel(SRTC_LPSR_ALP, ioaddr + SRTC_LPSR);
+
+ mxc_rtc_sync_lp_locked(ioaddr);
+ return 0;
+}
+
+/* This function is the RTC interrupt service routine. */
+static irqreturn_t mxc_rtc_interrupt(int irq, void *dev_id)
+{
+ struct platform_device *pdev = dev_id;
+ struct mxc_rtc_data *pdata = platform_get_drvdata(pdev);
+ void __iomem *ioaddr = pdata->ioaddr;
+ unsigned long flags;
+ u32 events = 0;
+ u32 lp_status;
+ u32 lp_cr;
+
+ spin_lock_irqsave(&pdata->lock, flags);
+ if (clk_prepare_enable(pdata->clk)) {
+ spin_unlock_irqrestore(&pdata->lock, flags);
+ return IRQ_NONE;
+ }
+
+ lp_status = readl(ioaddr + SRTC_LPSR);
+ lp_cr = readl(ioaddr + SRTC_LPCR);
+
+ /* update irq data & counter */
+ if (lp_status & SRTC_LPSR_ALP) {
+ if (lp_cr & SRTC_LPCR_ALP)
+ events = (RTC_AF | RTC_IRQF);
+
+ /* disable further lp alarm interrupts */
+ lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
+ }
+
+ /* Update interrupt enables */
+ writel(lp_cr, ioaddr + SRTC_LPCR);
+
+ /* clear interrupt status */
+ writel(lp_status, ioaddr + SRTC_LPSR);
+
+ mxc_rtc_sync_lp_locked(ioaddr);
+ rtc_update_irq(pdata->rtc, 1, events);
+ clk_disable_unprepare(pdata->clk);
+ spin_unlock_irqrestore(&pdata->lock, flags);
+ return IRQ_HANDLED;
+}
+
+/*
+ * Enable clk and aquire spinlock
+ * @return 0 if successful; non-zero otherwise.
+ */
+static int mxc_rtc_lock(struct mxc_rtc_data *const pdata)
+{
+ int ret;
+
+ spin_lock_irq(&pdata->lock);
+ ret = clk_prepare_enable(pdata->clk);
+ if (ret) {
+ spin_unlock_irq(&pdata->lock);
+ return ret;
+ }
+ return 0;
+}
+
+static int mxc_rtc_unlock(struct mxc_rtc_data *const pdata)
+{
+ clk_disable_unprepare(pdata->clk);
+ spin_unlock_irq(&pdata->lock);
+ return 0;
+}
+
+/*
+ * This function reads the current RTC time into tm in Gregorian date.
+ *
+ * @param tm contains the RTC time value upon return
+ *
+ * @return 0 if successful; non-zero otherwise.
+ */
+static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
+ time_t now;
+ int ret = mxc_rtc_lock(pdata);
+
+ if (ret)
+ return ret;
+
+ now = readl(pdata->ioaddr + SRTC_LPSCMR);
+ rtc_time_to_tm(now, tm);
+ ret = rtc_valid_tm(tm);
+ mxc_rtc_unlock(pdata);
+ return ret;
+}
+
+/*
+ * This function sets the internal RTC time based on tm in Gregorian date.
+ *
+ * @param tm the time value to be set in the RTC
+ *
+ * @return 0 if successful; non-zero otherwise.
+ */
+static int mxc_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
+ time64_t time = rtc_tm_to_time64(tm);
+ int ret;
+
+ if (time > U32_MAX) {
+ dev_err(dev, "RTC exceeded by %llus\n", time - U32_MAX);
+ return -EINVAL;
+ }
+
+ ret = mxc_rtc_lock(pdata);
+ if (ret)
+ return ret;
+
+ writel(time, pdata->ioaddr + SRTC_LPSCMR);
+ mxc_rtc_sync_lp_locked(pdata->ioaddr);
+ return mxc_rtc_unlock(pdata);
+}
+
+/*
+ * This function reads the current alarm value into the passed in \b alrm
+ * argument. It updates the \b alrm's pending field value based on the whether
+ * an alarm interrupt occurs or not.
+ *
+ * @param alrm contains the RTC alarm value upon return
+ *
+ * @return 0 if successful; non-zero otherwise.
+ */
+static int mxc_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
+ void __iomem *ioaddr = pdata->ioaddr;
+ int ret;
+
+ ret = mxc_rtc_lock(pdata);
+ if (ret)
+ return ret;
+
+ rtc_time_to_tm(readl(ioaddr + SRTC_LPSAR), &alrm->time);
+ alrm->pending = !!(readl(ioaddr + SRTC_LPSR) & SRTC_LPSR_ALP);
+ return mxc_rtc_unlock(pdata);
+}
+
+/*
+ * Enable/Disable alarm interrupt
+ * The caller should hold the pdata->lock
+ */
+static void mxc_rtc_alarm_irq_enable_locked(struct mxc_rtc_data *pdata,
+ unsigned int enable)
+{
+ u32 lp_cr = readl(pdata->ioaddr + SRTC_LPCR);
+
+ if (enable)
+ lp_cr |= (SRTC_LPCR_ALP | SRTC_LPCR_WAE);
+ else
+ lp_cr &= ~(SRTC_LPCR_ALP | SRTC_LPCR_WAE);
+
+ writel(lp_cr, pdata->ioaddr + SRTC_LPCR);
+}
+
+static int mxc_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
+{
+ struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
+ int ret = mxc_rtc_lock(pdata);
+
+ if (ret)
+ return ret;
+
+ mxc_rtc_alarm_irq_enable_locked(pdata, enable);
+ return mxc_rtc_unlock(pdata);
+}
+
+/*
+ * This function sets the RTC alarm based on passed in alrm.
+ *
+ * @param alrm the alarm value to be set in the RTC
+ *
+ * @return 0 if successful; non-zero otherwise.
+ */
+static int mxc_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
+ int ret = mxc_rtc_lock(pdata);
+
+ if (ret)
+ return ret;
+
+ ret = mxc_rtc_write_alarm_locked(pdata, &alrm->time);
+ if (!ret) {
+ mxc_rtc_alarm_irq_enable_locked(pdata, alrm->enabled);
+ mxc_rtc_sync_lp_locked(pdata->ioaddr);
+ }
+ mxc_rtc_unlock(pdata);
+ return ret;
+}
+
+static const struct rtc_class_ops mxc_rtc_ops = {
+ .read_time = mxc_rtc_read_time,
+ .set_time = mxc_rtc_set_time,
+ .read_alarm = mxc_rtc_read_alarm,
+ .set_alarm = mxc_rtc_set_alarm,
+ .alarm_irq_enable = mxc_rtc_alarm_irq_enable,
+};
+
+static int mxc_rtc_wait_for_flag(void *__iomem ioaddr, int flag)
+{
+ unsigned int timeout = REG_READ_TIMEOUT;
+
+ while (!(readl(ioaddr) & flag)) {
+ if (!--timeout) {
+ pr_err("Wait timeout for 0x%x@%p!\n", flag, ioaddr);
+ return -EBUSY;
+ }
+ }
+ return 0;
+}
+
+static int mxc_rtc_probe(struct platform_device *pdev)
+{
+ struct mxc_rtc_data *pdata;
+ struct resource *res;
+ void __iomem *ioaddr;
+ int ret = 0;
+
+ pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+ if (!pdata)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ pdata->ioaddr = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(pdata->ioaddr))
+ return PTR_ERR(pdata->ioaddr);
+
+ ioaddr = pdata->ioaddr;
+
+ pdata->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(pdata->clk)) {
+ dev_err(&pdev->dev, "unable to get rtc clock!\n");
+ return PTR_ERR(pdata->clk);
+ }
+
+ spin_lock_init(&pdata->lock);
+ pdata->irq = platform_get_irq(pdev, 0);
+ if (pdata->irq < 0)
+ return pdata->irq;
+
+ device_init_wakeup(&pdev->dev, 1);
+
+ ret = clk_prepare_enable(pdata->clk);
+ if (ret)
+ return ret;
+ /* initialize glitch detect */
+ writel(SRTC_LPPDR_INIT, ioaddr + SRTC_LPPDR);
+
+ /* clear lp interrupt status */
+ writel(0xFFFFFFFF, ioaddr + SRTC_LPSR);
+
+ /* move out of init state */
+ writel((SRTC_LPCR_IE | SRTC_LPCR_NSA), ioaddr + SRTC_LPCR);
+ mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_IES);
+
+ /* move out of non-valid state */
+ writel((SRTC_LPCR_IE | SRTC_LPCR_NVE | SRTC_LPCR_NSA |
+ SRTC_LPCR_EN_LP), ioaddr + SRTC_LPCR);
+ mxc_rtc_wait_for_flag(ioaddr + SRTC_LPSR, SRTC_LPSR_NVES);
+
+ clk_disable_unprepare(pdata->clk);
+ platform_set_drvdata(pdev, pdata);
+ ret =
+ devm_request_irq(&pdev->dev, pdata->irq, mxc_rtc_interrupt, 0,
+ pdev->name, pdev);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "interrupt not available.\n");
+ return ret;
+ }
+
+ pdata->rtc =
+ devm_rtc_device_register(&pdev->dev, pdev->name, &mxc_rtc_ops,
+ THIS_MODULE);
+ if (IS_ERR(pdata->rtc))
+ return PTR_ERR(pdata->rtc);
+
+ return 0;
+}
+
+static int __exit mxc_rtc_remove(struct platform_device *pdev)
+{
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mxc_rtc_suspend(struct device *dev)
+{
+ struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ enable_irq_wake(pdata->irq);
+
+ return 0;
+}
+
+static int mxc_rtc_resume(struct device *dev)
+{
+ struct mxc_rtc_data *pdata = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ disable_irq_wake(pdata->irq);
+
+ return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(mxc_rtc_pm_ops, mxc_rtc_suspend, mxc_rtc_resume);
+
+static const struct of_device_id mxc_ids[] = {
+ { .compatible = "fsl,imx53-rtc", },
+ {}
+};
+
+static struct platform_driver mxc_rtc_driver = {
+ .driver = {
+ .name = "mxc_rtc_v2",
+ .of_match_table = mxc_ids,
+ .pm = &mxc_rtc_pm_ops,
+ },
+ .probe = mxc_rtc_probe,
+ .remove = mxc_rtc_remove,
+};
+
+module_platform_driver(mxc_rtc_driver);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("Real Time Clock (RTC) Driver for i.MX53");
+MODULE_LICENSE("GPL");
--
2.11.0