[PATCH 2/3] rtc: Add support for the MSTAR MSC313 RTC

Romain Perier
2021-07-20T17:26:20Z

From: Daniel Palmer <daniel@0x0f.com>

This adds support for the RTC block on the Mstar MSC313e SoCs and newer.

Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Co-developed-by: Romain Perier <romain.perier@gmail.com>
Signed-off-by: Romain Perier <romain.perier@gmail.com>
---
MAINTAINERS | 1 +
drivers/rtc/Kconfig | 10 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-msc313.c | 246 +++++++++++++++++++++++++++++++++++++++
4 files changed, 258 insertions(+)
create mode 100644 drivers/rtc/rtc-msc313.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 6c8be735cc91..7e8d1a375e0d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2220,6 +2220,7 @@ F: arch/arm/boot/dts/mstar-*
F: arch/arm/mach-mstar/
F: drivers/clk/mstar/
F: drivers/gpio/gpio-msc313.c
+F: drivers/rtc/rtc-msc313.c
F: drivers/watchdog/msc313e_wdt.c
F: include/dt-bindings/clock/mstar-*
F: include/dt-bindings/gpio/msc313-gpio.h
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 12153d5801ce..67870b422bc5 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1925,4 +1925,14 @@ config RTC_DRV_WILCO_EC
This can also be built as a module. If so, the module will
be named "rtc_wilco_ec".

+config RTC_DRV_MSC313
+ tristate "MStar MSC313 RTC"
+ depends on ARCH_MSTARV7
+ help
+ If you say yes here you get support for the Mstar MSC313e On-Chip
+ Real Time Clock.
+
+ This driver can also be built as a module, if so, the module
+ will be called "rtc-msc313".
+
endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 2dd0dd956b0e..5efda8a60cee 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -101,6 +101,7 @@ obj-$(CONFIG_RTC_DRV_MCP795) += rtc-mcp795.o
obj-$(CONFIG_RTC_DRV_MESON) += rtc-meson.o
obj-$(CONFIG_RTC_DRV_MOXART) += rtc-moxart.o
obj-$(CONFIG_RTC_DRV_MPC5121) += rtc-mpc5121.o
+obj-$(CONFIG_RTC_DRV_MSC313) += rtc-msc313.o
obj-$(CONFIG_RTC_DRV_MSM6242) += rtc-msm6242.o
obj-$(CONFIG_RTC_DRV_MT2712) += rtc-mt2712.o
obj-$(CONFIG_RTC_DRV_MT6397) += rtc-mt6397.o
diff --git a/drivers/rtc/rtc-msc313.c b/drivers/rtc/rtc-msc313.c
new file mode 100644
index 000000000000..b1102e3c93ba
--- /dev/null
+++ b/drivers/rtc/rtc-msc313.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Real time clocks driver for MStar/SigmaStar ARMv7 SoCs.
+ * Based on "Real Time Clock driver for msb252x." that was contained
+ * in various MStar kernels.
+ *
+ * (C) 2019 Daniel Palmer
+ * (C) 2021 Romain Perier
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+/* Registers */
+#define REG_RTC_CTRL 0x00
+#define REG_RTC_FREQ_CW_L 0x04
+#define REG_RTC_FREQ_CW_H 0x08
+#define REG_RTC_LOAD_VAL_L 0x0C
+#define REG_RTC_LOAD_VAL_H 0x10
+#define REG_RTC_MATCH_VAL_L 0x14
+#define REG_RTC_MATCH_VAL_H 0x18
+#define REG_RTC_CNT_VAL_L 0x20
+#define REG_RTC_CNT_VAL_H 0x24
+
+#define SOFT_RSTZ_BIT BIT(0)
+#define CNT_EN_BIT BIT(1)
+#define WRAP_EN_BIT BIT(2)
+#define LOAD_EN_BIT BIT(3)
+#define READ_EN_BIT BIT(4)
+#define INT_MASK_BIT BIT(5)
+#define INT_FORCE_BIT BIT(6)
+#define INT_CLEAR_BIT BIT(7)
+
+struct msc313_rtc {
+ struct rtc_device *rtc_dev;
+ void __iomem *rtc_base;
+ struct clk *clk;
+};
+
+static int msc313_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct msc313_rtc *priv = dev_get_drvdata(dev);
+ unsigned long seconds;
+
+ seconds = readw(priv->rtc_base + REG_RTC_MATCH_VAL_L)
+ | (readw(priv->rtc_base + REG_RTC_MATCH_VAL_H) << 16);
+
+ rtc_time64_to_tm(seconds, &alarm->time);
+
+ if (!(readw(priv->rtc_base + REG_RTC_CTRL) & INT_MASK_BIT))
+ alarm->enabled = 1;
+
+ return 0;
+}
+
+static int msc313_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct msc313_rtc *priv = dev_get_drvdata(dev);
+ u16 reg;
+
+ reg = readw(priv->rtc_base + REG_RTC_CTRL);
+ if (enabled)
+ reg &= ~INT_MASK_BIT;
+ else
+ reg |= INT_MASK_BIT;
+ writew(reg, priv->rtc_base + REG_RTC_CTRL);
+ return 0;
+}
+
+static int msc313_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct msc313_rtc *priv = dev_get_drvdata(dev);
+ unsigned long seconds;
+
+ seconds = rtc_tm_to_time64(&alarm->time);
+ writew((seconds & 0xFFFF), priv->rtc_base + REG_RTC_MATCH_VAL_L);
+ writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_MATCH_VAL_H);
+
+ msc313_rtc_alarm_irq_enable(dev, alarm->enabled);
+
+ return 0;
+}
+
+static int msc313_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct msc313_rtc *priv = dev_get_drvdata(dev);
+ u32 seconds;
+ u16 reg;
+
+ reg = readw(priv->rtc_base + REG_RTC_CTRL);
+ writew(reg | READ_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
+
+ /* Wait for HW latch done */
+ while (readw(priv->rtc_base + REG_RTC_CTRL) & READ_EN_BIT)
+ udelay(1);
+
+ seconds = readw(priv->rtc_base + REG_RTC_CNT_VAL_L)
+ | (readw(priv->rtc_base + REG_RTC_CNT_VAL_H) << 16);
+
+ rtc_time64_to_tm(seconds, tm);
+
+ return rtc_valid_tm(tm);
+}
+
+static int msc313_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct msc313_rtc *priv = dev_get_drvdata(dev);
+ unsigned long seconds;
+ u16 reg;
+
+ seconds = rtc_tm_to_time64(tm);
+ writew(seconds & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_L);
+ writew((seconds >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_LOAD_VAL_H);
+ reg = readw(priv->rtc_base + REG_RTC_CTRL);
+ writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
+
+ /* need to check carefully if we want to clear REG_RTC_LOAD_VAL_H for customer*/
+ while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT)
+ udelay(1);
+ writew(0, priv->rtc_base + REG_RTC_LOAD_VAL_H);
+
+ return 0;
+}
+
+static const struct rtc_class_ops msc313_rtc_ops = {
+ .read_time = msc313_rtc_read_time,
+ .set_time = msc313_rtc_set_time,
+ .read_alarm = msc313_rtc_read_alarm,
+ .set_alarm = msc313_rtc_set_alarm,
+ .alarm_irq_enable = msc313_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t msc313_rtc_interrupt(s32 irq, void *dev_id)
+{
+ struct msc313_rtc *priv = dev_get_drvdata(dev_id);
+ u16 reg;
+
+ reg = readw_relaxed(priv->rtc_base + REG_RTC_CTRL);
+ reg |= INT_CLEAR_BIT;
+ reg &= ~INT_FORCE_BIT;
+ writew_relaxed(reg, priv->rtc_base + REG_RTC_CTRL);
+
+ rtc_update_irq(priv->rtc_dev, 1, RTC_IRQF | RTC_AF);
+
+ return IRQ_HANDLED;
+}
+
+static int msc313_rtc_remove(struct platform_device *pdev)
+{
+ struct msc313_rtc *priv = platform_get_drvdata(pdev);
+
+ clk_disable_unprepare(priv->clk);
+
+ return 0;
+}
+
+static int msc313_rtc_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct msc313_rtc *priv;
+ int ret;
+ int irq;
+ unsigned long rate;
+ u16 reg;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(struct msc313_rtc), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->rtc_base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->rtc_base))
+ return PTR_ERR(priv->rtc_base);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return -EINVAL;
+
+ ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED,
+ dev_name(&pdev->dev), &pdev->dev);
+ if (ret) {
+ dev_err(dev, "Unable to request irq\n");
+ return ret;
+ }
+
+ priv->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(priv->clk)) {
+ dev_err(dev, "No input reference clock\n");
+ return PTR_ERR(priv->clk);
+ }
+
+ ret = clk_prepare_enable(priv->clk);
+ if (ret) {
+ dev_err(dev, "Failed to enable the reference clock, %d\n", ret);
+ return ret;
+ }
+
+ rate = clk_get_rate(priv->clk);
+
+ reg = readw(priv->rtc_base + REG_RTC_CTRL);
+ if (!(reg & SOFT_RSTZ_BIT)) {
+ reg |= SOFT_RSTZ_BIT;
+ writew(reg, priv->rtc_base + REG_RTC_CTRL);
+ }
+
+ writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L);
+ writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H);
+
+ reg |= CNT_EN_BIT;
+ writew(reg, priv->rtc_base + REG_RTC_CTRL);
+
+ platform_set_drvdata(pdev, priv);
+
+ priv->rtc_dev = devm_rtc_device_register(dev, dev_name(dev), &msc313_rtc_ops, THIS_MODULE);
+ if (IS_ERR(priv->rtc_dev)) {
+ dev_err(dev, "Failed to register rtc device\n");
+ return PTR_ERR(priv->rtc_dev);
+ }
+
+ return 0;
+}
+
+static const struct of_device_id msc313_rtc_of_match_table[] = {
+ { .compatible = "mstar,msc313-rtc" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ms_rtc_of_match_table);
+
+static struct platform_driver msc313_rtc_driver = {
+ .remove = msc313_rtc_remove,
+ .probe = msc313_rtc_probe,
+ .driver = {
+ .name = "msc313-rtc",
+ .of_match_table = msc313_rtc_of_match_table,
+ },
+};
+
+module_platform_driver(msc313_rtc_driver);
+
+MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
+MODULE_AUTHOR("Romain Perier <romain.perier@gmail.com>");
+MODULE_DESCRIPTION("MStar RTC Driver");
+MODULE_LICENSE("GPL v2");
--
2.30.2