--- /dev/null
+// 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_STATUS_INT 0x1C
+#define REG_RTC_CNT_VAL_L 0x20
+#define REG_RTC_CNT_VAL_H 0x24
+
+/* Control bits for REG_RTC_CTRL */
+#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)
+
+/* Control bits for REG_RTC_STATUS_INT */
+#define RAW_INT_BIT BIT(0)
+#define ALM_INT_BIT BIT(1)
+
+struct msc313_rtc {
+ struct rtc_device *rtc_dev;
+ void __iomem *rtc_base;
+};
+
+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 bool msc313_rtc_get_enabled(struct msc313_rtc *priv)
+{
+ return readw(priv->rtc_base + REG_RTC_CTRL) & CNT_EN_BIT;
+}
+
+static void msc313_rtc_set_enabled(struct msc313_rtc *priv)
+{
+ u16 reg;
+
+ reg = readw(priv->rtc_base + REG_RTC_CTRL);
+ reg |= CNT_EN_BIT;
+ writew(reg, priv->rtc_base + REG_RTC_CTRL);
+}
+
+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;
+
+ if (!msc313_rtc_get_enabled(priv))
+ return -EINVAL;
+
+ 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 0;
+}
+
+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);
+
+ /* Enable load for loading value into internal RTC counter */
+ reg = readw(priv->rtc_base + REG_RTC_CTRL);
+ writew(reg | LOAD_EN_BIT, priv->rtc_base + REG_RTC_CTRL);
+
+ /* Wait for HW latch done */
+ while (readw(priv->rtc_base + REG_RTC_CTRL) & LOAD_EN_BIT)
+ udelay(1);
+ msc313_rtc_set_enabled(priv);
+ 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(priv->rtc_base + REG_RTC_STATUS_INT);
+ if (!(reg & ALM_INT_BIT))
+ return IRQ_NONE;
+
+ reg = readw(priv->rtc_base + REG_RTC_CTRL);
+ reg |= INT_CLEAR_BIT;
+ reg &= ~INT_FORCE_BIT;
+ writew(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_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct msc313_rtc *priv;
+ unsigned long rate;
+ struct clk *clk;
+ int ret;
+ int irq;
+
+ 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;
+
+ priv->rtc_dev = devm_rtc_allocate_device(dev);
+ if (IS_ERR(priv->rtc_dev))
+ return PTR_ERR(priv->rtc_dev);
+
+ priv->rtc_dev->ops = &msc313_rtc_ops;
+ priv->rtc_dev->range_max = U32_MAX;
+
+ ret = devm_request_irq(dev, irq, msc313_rtc_interrupt, IRQF_SHARED,
+ dev_name(&pdev->dev), &pdev->dev);
+ if (ret) {
+ dev_err(dev, "Could not request IRQ\n");
+ return ret;
+ }
+
+ clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(clk)) {
+ dev_err(dev, "No input reference clock\n");
+ return PTR_ERR(clk);
+ }
+
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ dev_err(dev, "Failed to enable the reference clock, %d\n", ret);
+ return ret;
+ }
+
+ ret = devm_add_action_or_reset(dev, (void (*) (void *))clk_disable_unprepare, clk);
+ if (ret)
+ return ret;
+
+ rate = clk_get_rate(clk);
+ writew(rate & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_L);
+ writew((rate >> 16) & 0xFFFF, priv->rtc_base + REG_RTC_FREQ_CW_H);
+
+ platform_set_drvdata(pdev, priv);
+
+ return devm_rtc_register_device(priv->rtc_dev);
+}
+
+static const struct of_device_id msc313_rtc_of_match_table[] = {
+ { .compatible = "mstar,msc313-rtc" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, msc313_rtc_of_match_table);
+
+static struct platform_driver msc313_rtc_driver = {
+ .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");
projects / linux.git / commitdiff