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Subject[PATCH v5 1/2] rtc: Add driver for Microchip PolarFire SoC
Date
Add support for the built-in RTC on Microchip PolarFire SoC

Co-Developed-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Daire McNamara <daire.mcnamara@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
drivers/rtc/Kconfig | 10 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-mpfs.c | 326 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 337 insertions(+)
create mode 100644 drivers/rtc/rtc-mpfs.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 41c65b4d2baf..a194422328da 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1966,4 +1966,14 @@ config RTC_DRV_MSC313
This driver can also be built as a module, if so, the module
will be called "rtc-msc313".

+config RTC_DRV_POLARFIRE_SOC
+ tristate "Microchip PolarFire SoC built-in RTC"
+ depends on SOC_MICROCHIP_POLARFIRE
+ help
+ If you say yes here you will get support for the
+ built-in RTC on Polarfire SoC.
+
+ This driver can also be built as a module, if so, the module
+ will be called "rtc-mpfs".
+
endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 2d827d8261d5..25ee5ba870a9 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -130,6 +130,7 @@ obj-$(CONFIG_RTC_DRV_PIC32) += rtc-pic32.o
obj-$(CONFIG_RTC_DRV_PL030) += rtc-pl030.o
obj-$(CONFIG_RTC_DRV_PL031) += rtc-pl031.o
obj-$(CONFIG_RTC_DRV_PM8XXX) += rtc-pm8xxx.o
+obj-$(CONFIG_RTC_DRV_POLARFIRE_SOC) += rtc-mpfs.o
obj-$(CONFIG_RTC_DRV_PS3) += rtc-ps3.o
obj-$(CONFIG_RTC_DRV_PXA) += rtc-pxa.o
obj-$(CONFIG_RTC_DRV_R7301) += rtc-r7301.o
diff --git a/drivers/rtc/rtc-mpfs.c b/drivers/rtc/rtc-mpfs.c
new file mode 100644
index 000000000000..db9c638e50f7
--- /dev/null
+++ b/drivers/rtc/rtc-mpfs.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip MPFS RTC driver
+ *
+ * Copyright (c) 2021-2022 Microchip Corporation. All rights reserved.
+ *
+ * Author: Daire McNamara <daire.mcnamara@microchip.com>
+ * & Conor Dooley <conor.dooley@microchip.com>
+ */
+#include "linux/bits.h"
+#include "linux/iopoll.h"
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/slab.h>
+#include <linux/rtc.h>
+
+#define CONTROL_REG 0x00
+#define MODE_REG 0x04
+#define PRESCALER_REG 0x08
+#define ALARM_LOWER_REG 0x0c
+#define ALARM_UPPER_REG 0x10
+#define COMPARE_LOWER_REG 0x14
+#define COMPARE_UPPER_REG 0x18
+#define DATETIME_LOWER_REG 0x20
+#define DATETIME_UPPER_REG 0x24
+
+#define CONTROL_RUNNING_BIT BIT(0)
+#define CONTROL_START_BIT BIT(0)
+#define CONTROL_STOP_BIT BIT(1)
+#define CONTROL_ALARM_ON_BIT BIT(2)
+#define CONTROL_ALARM_OFF_BIT BIT(3)
+#define CONTROL_RESET_BIT BIT(4)
+#define CONTROL_UPLOAD_BIT BIT(5)
+#define CONTROL_DOWNLOAD_BIT BIT(6)
+#define CONTROL_MATCH_BIT BIT(7)
+#define CONTROL_WAKEUP_CLR_BIT BIT(8)
+#define CONTROL_WAKEUP_SET_BIT BIT(9)
+#define CONTROL_UPDATED_BIT BIT(10)
+
+#define MODE_CLOCK_CALENDAR BIT(0)
+#define MODE_WAKE_EN BIT(1)
+#define MODE_WAKE_RESET BIT(2)
+#define MODE_WAKE_CONTINUE BIT(3)
+
+#define MAX_PRESCALER_COUNT GENMASK(25, 0)
+#define DATETIME_UPPER_MASK GENMASK(29, 0)
+#define ALARM_UPPER_MASK GENMASK(10, 0)
+
+#define UPLOAD_TIMEOUT_US 50
+
+struct mpfs_rtc_dev {
+ struct rtc_device *rtc;
+ void __iomem *base;
+};
+
+static void mpfs_rtc_start(struct mpfs_rtc_dev *rtcdev)
+{
+ u32 ctrl;
+
+ ctrl = readl(rtcdev->base + CONTROL_REG);
+ ctrl &= ~CONTROL_STOP_BIT;
+ ctrl |= CONTROL_START_BIT;
+ writel(ctrl, rtcdev->base + CONTROL_REG);
+}
+
+static void mpfs_rtc_clear_irq(struct mpfs_rtc_dev *rtcdev)
+{
+ u32 val = readl(rtcdev->base + CONTROL_REG);
+
+ val &= ~(CONTROL_ALARM_ON_BIT | CONTROL_STOP_BIT);
+ val |= CONTROL_ALARM_OFF_BIT;
+ writel(val, rtcdev->base + CONTROL_REG);
+ /*
+ * Ensure that the posted write to the CONTROL_REG register completed before
+ * returning from this function. Not doing this may result in the interrupt
+ * only being cleared some time after this function returns.
+ */
+ (void)readl(rtcdev->base + CONTROL_REG);
+}
+
+static int mpfs_rtc_readtime(struct device *dev, struct rtc_time *tm)
+{
+ struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
+ u64 time;
+
+ time = readl(rtcdev->base + DATETIME_LOWER_REG);
+ time |= ((u64)readl(rtcdev->base + DATETIME_UPPER_REG) & DATETIME_UPPER_MASK) << 32;
+ rtc_time64_to_tm(time, tm);
+
+ return 0;
+}
+
+static int mpfs_rtc_settime(struct device *dev, struct rtc_time *tm)
+{
+ struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
+ u32 ctrl, prog;
+ u64 time;
+ int ret;
+
+ time = rtc_tm_to_time64(tm);
+
+ writel((u32)time, rtcdev->base + DATETIME_LOWER_REG);
+ writel((u32)(time >> 32) & DATETIME_UPPER_MASK, rtcdev->base + DATETIME_UPPER_REG);
+
+ ctrl = readl(rtcdev->base + CONTROL_REG);
+ ctrl &= ~CONTROL_STOP_BIT;
+ ctrl |= CONTROL_UPLOAD_BIT;
+ writel(ctrl, rtcdev->base + CONTROL_REG);
+
+ ret = read_poll_timeout(readl, prog, prog & CONTROL_UPLOAD_BIT, 0, UPLOAD_TIMEOUT_US,
+ false, rtcdev->base + CONTROL_REG);
+ if (ret) {
+ dev_err(dev, "timed out uploading time to rtc");
+ return ret;
+ }
+ mpfs_rtc_start(rtcdev);
+
+ return 0;
+}
+
+static int mpfs_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
+ u32 mode = readl(rtcdev->base + MODE_REG);
+ u64 time;
+
+ alrm->enabled = mode & MODE_WAKE_EN;
+
+ time = (u64)readl(rtcdev->base + ALARM_LOWER_REG) << 32;
+ time |= (readl(rtcdev->base + ALARM_UPPER_REG) & ALARM_UPPER_MASK);
+ rtc_time64_to_tm(time, &alrm->time);
+
+ return 0;
+}
+
+static int mpfs_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+ struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
+ u32 mode, ctrl;
+ u64 time;
+
+ /* Disable the alarm before updating */
+ ctrl = readl(rtcdev->base + CONTROL_REG);
+ ctrl |= CONTROL_ALARM_OFF_BIT;
+ writel(ctrl, rtcdev->base + CONTROL_REG);
+
+ time = rtc_tm_to_time64(&alrm->time);
+
+ writel((u32)time, rtcdev->base + ALARM_LOWER_REG);
+ writel((u32)(time >> 32) & ALARM_UPPER_MASK, rtcdev->base + ALARM_UPPER_REG);
+
+ /* Bypass compare register in alarm mode */
+ writel(GENMASK(31, 0), rtcdev->base + COMPARE_LOWER_REG);
+ writel(GENMASK(29, 0), rtcdev->base + COMPARE_UPPER_REG);
+
+ /* Configure the RTC to enable the alarm. */
+ ctrl = readl(rtcdev->base + CONTROL_REG);
+ mode = readl(rtcdev->base + MODE_REG);
+ if (alrm->enabled) {
+ mode = MODE_WAKE_EN | MODE_WAKE_CONTINUE;
+ /* Enable the alarm */
+ ctrl &= ~CONTROL_ALARM_OFF_BIT;
+ ctrl |= CONTROL_ALARM_ON_BIT;
+ }
+ ctrl &= ~CONTROL_STOP_BIT;
+ ctrl |= CONTROL_START_BIT;
+ writel(ctrl, rtcdev->base + CONTROL_REG);
+ writel(mode, rtcdev->base + MODE_REG);
+
+ return 0;
+}
+
+static int mpfs_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct mpfs_rtc_dev *rtcdev = dev_get_drvdata(dev);
+ u32 ctrl;
+
+ ctrl = readl(rtcdev->base + CONTROL_REG);
+ ctrl &= ~(CONTROL_ALARM_ON_BIT | CONTROL_ALARM_OFF_BIT | CONTROL_STOP_BIT);
+
+ if (enabled)
+ ctrl |= CONTROL_ALARM_ON_BIT;
+ else
+ ctrl |= CONTROL_ALARM_OFF_BIT;
+
+ writel(ctrl, rtcdev->base + CONTROL_REG);
+
+ return 0;
+}
+
+static inline struct clk *mpfs_rtc_init_clk(struct device *dev)
+{
+ struct clk *clk;
+ int ret;
+
+ clk = devm_clk_get(dev, "rtc");
+ if (IS_ERR(clk))
+ return clk;
+
+ ret = clk_prepare_enable(clk);
+ if (ret)
+ return ERR_PTR(ret);
+
+ devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk);
+ return clk;
+}
+
+static irqreturn_t mpfs_rtc_wakeup_irq_handler(int irq, void *dev)
+{
+ struct mpfs_rtc_dev *rtcdev = dev;
+ unsigned long pending;
+
+ pending = readl(rtcdev->base + CONTROL_REG);
+ pending &= CONTROL_ALARM_ON_BIT;
+ mpfs_rtc_clear_irq(rtcdev);
+
+ rtc_update_irq(rtcdev->rtc, 1, RTC_IRQF | RTC_AF);
+
+ return IRQ_HANDLED;
+}
+
+static const struct rtc_class_ops mpfs_rtc_ops = {
+ .read_time = mpfs_rtc_readtime,
+ .set_time = mpfs_rtc_settime,
+ .read_alarm = mpfs_rtc_readalarm,
+ .set_alarm = mpfs_rtc_setalarm,
+ .alarm_irq_enable = mpfs_rtc_alarm_irq_enable,
+};
+
+static int mpfs_rtc_probe(struct platform_device *pdev)
+{
+ struct mpfs_rtc_dev *rtcdev;
+ struct clk *clk;
+ u32 prescaler;
+ int wakeup_irq, ret;
+
+ rtcdev = devm_kzalloc(&pdev->dev, sizeof(struct mpfs_rtc_dev), GFP_KERNEL);
+ if (!rtcdev)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, rtcdev);
+
+ rtcdev->rtc = devm_rtc_allocate_device(&pdev->dev);
+ if (IS_ERR(rtcdev->rtc))
+ return PTR_ERR(rtcdev->rtc);
+
+ rtcdev->rtc->ops = &mpfs_rtc_ops;
+
+ /* range is capped by alarm max, lower reg is 31:0 & upper is 10:0 */
+ rtcdev->rtc->range_max = GENMASK_ULL(42, 0);
+
+ clk = mpfs_rtc_init_clk(&pdev->dev);
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ rtcdev->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(rtcdev->base)) {
+ dev_dbg(&pdev->dev, "invalid ioremap resources\n");
+ return PTR_ERR(rtcdev->base);
+ }
+
+ wakeup_irq = platform_get_irq(pdev, 0);
+ if (wakeup_irq <= 0) {
+ dev_dbg(&pdev->dev, "could not get wakeup irq\n");
+ return wakeup_irq;
+ }
+ ret = devm_request_irq(&pdev->dev, wakeup_irq, mpfs_rtc_wakeup_irq_handler, 0,
+ dev_name(&pdev->dev), rtcdev);
+ if (ret) {
+ dev_dbg(&pdev->dev, "could not request wakeup irq\n");
+ return ret;
+ }
+
+ /* prescaler hardware adds 1 to reg value */
+ prescaler = clk_get_rate(devm_clk_get(&pdev->dev, "rtcref")) - 1;
+
+ if (prescaler > MAX_PRESCALER_COUNT) {
+ dev_dbg(&pdev->dev, "invalid prescaler %d\n", prescaler);
+ return -EINVAL;
+ }
+
+ writel(prescaler, rtcdev->base + PRESCALER_REG);
+ dev_info(&pdev->dev, "prescaler set to: 0x%X \r\n", prescaler);
+
+ device_init_wakeup(&pdev->dev, true);
+ ret = dev_pm_set_wake_irq(&pdev->dev, wakeup_irq);
+ if (ret)
+ dev_err(&pdev->dev, "failed to enable irq wake\n");
+
+ return devm_rtc_register_device(rtcdev->rtc);
+}
+
+static int mpfs_rtc_remove(struct platform_device *pdev)
+{
+ dev_pm_clear_wake_irq(&pdev->dev);
+
+ return 0;
+}
+
+static const struct of_device_id mpfs_rtc_of_match[] = {
+ { .compatible = "microchip,mpfs-rtc" },
+ { }
+};
+
+MODULE_DEVICE_TABLE(of, mpfs_rtc_of_match);
+
+static struct platform_driver mpfs_rtc_driver = {
+ .probe = mpfs_rtc_probe,
+ .remove = mpfs_rtc_remove,
+ .driver = {
+ .name = "mpfs_rtc",
+ .of_match_table = mpfs_rtc_of_match,
+ },
+};
+
+module_platform_driver(mpfs_rtc_driver);
+
+MODULE_DESCRIPTION("Real time clock for Microchip Polarfire SoC");
+MODULE_AUTHOR("Daire McNamara <daire.mcnamara@microchip.com>");
+MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
+MODULE_LICENSE("GPL");
--
2.36.1
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