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From:   Vincent Shih <vincent.sunplus@gmail.com>
To:     a.zummo@towertech.it, alexandre.belloni@bootlin.com,
        p.zabel@pengutronix.de, linux-kernel@vger.kernel.org,
        linux-rtc@vger.kernel.org, robh+dt@kernel.org,
        devicetree@vger.kernel.org, wells.lu@sunplus.com,
        in-reply-to=1635834123-24668-1-git-send-email-vincent.shih@sunplus.com
Cc:     Vincent Shih <vincent.shih@sunplus.com>
Subject: [PATCH v2 1/2] rtc: Add driver for Sunplus SP7021
Date:   Tue,  9 Nov 2021 14:38:17 +0800
Message-Id: <1636439898-7358-2-git-send-email-vincent.shih@sunplus.com>
In-Reply-To: <1636439898-7358-1-git-send-email-vincent.shih@sunplus.com>
References: <1636439898-7358-1-git-send-email-vincent.shih@sunplus.com>
Precedence: bulk

Add driver for Sunplus SP7021

Signed-off-by: Vincent Shih <vincent.shih@sunplus.com>
---
Changes in v2:
 - Addressed the comments from Mr. Philipp Zabel
 - Addressed the comments from Mr. Randy Dunlap
 - Addressed the comments from Mr. Alexandre Belloni
 - Sorted the files in Makefile

 MAINTAINERS               |   6 +
 drivers/rtc/Kconfig       |  11 ++
 drivers/rtc/Makefile      |   1 +
 drivers/rtc/rtc-sunplus.c | 370 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 388 insertions(+)
 create mode 100644 drivers/rtc/rtc-sunplus.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 3b79fd4..6c1a535 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17945,6 +17945,12 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/net/ethernet/dlink/sundance.c
 
+SUNPLUS RTC DRIVER
+M:	Vincent Shih <vincent.shih@sunplus.com>
+L:	linux-rtc@vger.kernel.org
+S:	Maintained
+F:	drivers/rtc/rtc-sunplus.c
+
 SUPERH
 M:	Yoshinori Sato <ysato@users.sourceforge.jp>
 M:	Rich Felker <dalias@libc.org>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index e1bc521..7ca6765 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1028,6 +1028,17 @@ config RTC_DRV_DS1685_FAMILY
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-ds1685.
 
+config RTC_DRV_SUNPLUS
+	bool "Sunplus SP7021 RTC"
+	depends on SOC_SP7021
+	help
+	  Say 'yes' to get support for Sunplus SP7021 real-time clock
+	  (RTC) for industrial applications.
+
+	  It provides RTC status check, timer/alarm functionalities,
+	  user data reservation only with battery with voltage over 2.5V,
+	  RTC power status check and battery charge.
+
 choice
 	prompt "Subtype"
 	depends on RTC_DRV_DS1685_FAMILY
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 5ceeafe..93cb4b2 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -164,6 +164,7 @@ obj-$(CONFIG_RTC_DRV_STM32) 	+= rtc-stm32.o
 obj-$(CONFIG_RTC_DRV_STMP)	+= rtc-stmp3xxx.o
 obj-$(CONFIG_RTC_DRV_SUN4V)	+= rtc-sun4v.o
 obj-$(CONFIG_RTC_DRV_SUN6I)	+= rtc-sun6i.o
+obj-$(CONFIG_RTC_DRV_SUNPLUS)	+= rtc-sunplus.o
 obj-$(CONFIG_RTC_DRV_SUNXI)	+= rtc-sunxi.o
 obj-$(CONFIG_RTC_DRV_TEGRA)	+= rtc-tegra.o
 obj-$(CONFIG_RTC_DRV_TEST)	+= rtc-test.o
diff --git a/drivers/rtc/rtc-sunplus.c b/drivers/rtc/rtc-sunplus.c
new file mode 100644
index 0000000..73c400d
--- /dev/null
+++ b/drivers/rtc/rtc-sunplus.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*												  */
+/* The RTC driver for Sunplus	SP7021								  */
+/*												  */
+/* Copyright (C) 2019 Sunplus Technology Inc., All rights reseerved.				  */
+/*												  */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/reset.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+
+#define RTC_REG_NAME			"rtc_reg"
+
+#define RTC_CTRL			0x40
+#define TIMER_FREEZE			(0x1 << 5)
+#define TIMER_FREEZE_MASK		(1 << (5 + 16))
+#define DIS_SYS_RST_RTC			(0x1 << 4)
+#define DIS_SYS_RST_RTC_MASK		(1 << (4 + 16))
+#define RTC32K_MODE_RESET		(0x1 << 3)
+#define RTC32K_MODE_RESET_MASK		(1 << (3 + 16))
+#define ALARM_EN_OVERDUE		(0x1 << 2)
+#define ALARM_EN_OVERDUE_MASK		(1 << (2 + 16))
+#define ALARM_EN_PMC			(0x1 << 1)
+#define ALARM_EN_PMC_MASK		(1 << (1 + 16))
+#define ALARM_EN			(0x1 << 0)
+#define ALARM_EN_MASK			(1 << (0 + 16))
+#define RTC_TIMER_OUT			0x44
+#define RTC_DIVIDER			0x48
+#define RTC_TIMER_SET			0x4c
+#define RTC_ALARM_SET			0x50
+#define RTC_USER_DATA			0x54
+#define RTC_RESET_RECORD		0x58
+#define RTC_BATTERY_CTRL		0x5c
+#define BAT_CHARGE_RSEL_2K_OHM		(0x0 << 2)
+#define BAT_CHARGE_RSEL_250_OHM		(0x1 << 2)
+#define BAT_CHARGE_RSEL_50_OHM		(0x2 << 2)
+#define BAT_CHARGE_RSEL_0_OHM		(0x3 << 2)
+#define BAT_CHARGE_RSEL_MASK		(0x3 << (2 + 16))
+#define BAT_CHARGE_DSEL_ON		(0x0 << 1)
+#define BAT_CHARGE_DSEL_OFF		(0x1 << 1)
+#define BAT_CHARGE_DSEL_MASK		(0x1 << (1 + 16))
+#define BAT_CHARGE_EN			(0x1 << 0)
+#define BAT_CHARGE_EN_MASK		(0x1 << (0 + 16))
+#define RTC_TRIM_CTRL			0x60
+
+struct sunplus_rtc {
+	struct clk *rtcclk;
+	struct reset_control *rstc;
+	void __iomem *base;
+	u32 ohms;
+};
+
+struct sunplus_rtc sp_rtc;
+
+static void sp_get_seconds(unsigned long *secs)
+{
+	*secs = (unsigned long)readl(sp_rtc.base + RTC_TIMER_OUT);
+}
+
+static void sp_set_seconds(unsigned long secs)
+{
+	writel((u32)secs, sp_rtc.base + RTC_TIMER_SET);
+}
+
+static int sp_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	unsigned long secs;
+
+	sp_get_seconds(&secs);
+	rtc_time64_to_tm(secs, tm);
+	dev_dbg(dev, "%s:  RTC date/time to %d-%d-%d, %02d:%02d:%02d.\r\n",
+		__func__, tm->tm_mday, tm->tm_mon + 1, tm->tm_year,
+					tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return rtc_valid_tm(tm);
+}
+
+int sp_rtc_get_time(struct rtc_time *tm)
+{
+	unsigned long secs;
+
+	sp_get_seconds(&secs);
+	rtc_time64_to_tm(secs, tm);
+
+	return 0;
+}
+
+static int sp_rtc_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	dev_dbg(&pdev->dev, "[RTC] Debug: %s(%d)\n", __func__, __LINE__);
+
+	// Keep RTC from system reset
+	writel(DIS_SYS_RST_RTC_MASK | DIS_SYS_RST_RTC, sp_rtc.base + RTC_CTRL);
+
+	return 0;
+}
+
+static int sp_rtc_resume(struct platform_device *pdev)
+{
+	/*						*/
+	/* Because RTC is still powered during suspend,	*/
+	/* there is nothing to do here.			*/
+	/*						*/
+	dev_dbg(&pdev->dev, "[RTC] Debug: %s(%d)\n", __func__, __LINE__);
+
+	// Keep RTC from system reset
+	writel(DIS_SYS_RST_RTC_MASK | DIS_SYS_RST_RTC, sp_rtc.base + RTC_CTRL);
+
+	return 0;
+}
+
+static int sp_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	unsigned long secs;
+
+	secs = rtc_tm_to_time64(tm);
+	dev_dbg(dev, "%s, secs = %lu\n", __func__, secs);
+	sp_set_seconds(secs);
+
+	return 0;
+}
+
+static int sp_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	unsigned long alarm_time;
+
+	alarm_time = rtc_tm_to_time64(&alrm->time);
+	dev_dbg(dev, "%s, alarm_time: %u\n", __func__, (u32)(alarm_time));
+	writel((u32)alarm_time, sp_rtc.base + RTC_ALARM_SET);
+
+	return 0;
+}
+
+static int sp_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	unsigned int alarm_time;
+
+	alarm_time = readl(sp_rtc.base + RTC_ALARM_SET);
+	dev_dbg(dev, "%s, alarm_time: %u\n", __func__, alarm_time);
+
+	if (alarm_time == 0) {
+		// alarm is disabled
+		alrm->enabled = 0;
+	} else {
+		// alarm is enabled
+		alrm->enabled = 1;
+		rtc_time64_to_tm((unsigned long)(alarm_time), &alrm->time);
+	}
+
+	return 0;
+}
+
+static int sp_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	if (enabled)
+		writel((TIMER_FREEZE_MASK | DIS_SYS_RST_RTC_MASK | RTC32K_MODE_RESET_MASK |
+				ALARM_EN_OVERDUE_MASK | ALARM_EN_PMC_MASK | ALARM_EN_MASK) |
+					(DIS_SYS_RST_RTC | ALARM_EN_OVERDUE | ALARM_EN_PMC |
+						ALARM_EN), sp_rtc.base + RTC_CTRL);
+	else
+		writel((ALARM_EN_OVERDUE_MASK | ALARM_EN_PMC_MASK | ALARM_EN_MASK) | 0x0,
+				sp_rtc.base + RTC_CTRL);
+
+	return 0;
+}
+
+static const struct rtc_class_ops sp_rtc_ops = {
+	.read_time =		sp_rtc_read_time,
+	.set_time =		sp_rtc_set_time,
+	.set_alarm =		sp_rtc_set_alarm,
+	.read_alarm =		sp_rtc_read_alarm,
+	.alarm_irq_enable =	sp_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t rtc_irq_handler(int irq, void *dev_id)
+{
+	struct platform_device *plat_dev = dev_id;
+	struct rtc_device *rtc = platform_get_drvdata(plat_dev);
+
+	rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
+	dev_dbg(&plat_dev->dev, "[RTC] ALARM INT\n");
+
+	return IRQ_HANDLED;
+}
+
+/* ---------------------------------------------------------------------------------------------- */
+/* bat_charge_rsel   bat_charge_dsel   bat_charge_en     Remarks				  */
+/*         x              x                 0            Disable				  */
+/*         0              0                 1            0.86mA (2K Ohm with diode)		  */
+/*         1              0                 1            1.81mA (250 Ohm with diode)		  */
+/*         2              0                 1            2.07mA (50 Ohm with diode)		  */
+/*         3              0                 1            16.0mA (0 Ohm with diode)		  */
+/*         0              1                 1            1.36mA (2K Ohm without diode)		  */
+/*         1              1                 1            3.99mA (250 Ohm without diode)		  */
+/*         2              1                 1            4.41mA (50 Ohm without diode)		  */
+/*         3              1                 1            16.0mA (0 Ohm without diode)		  */
+/* ---------------------------------------------------------------------------------------------- */
+static void sp_rtc_set_trickle_charger(struct device dev)
+{
+	int ret;
+	u32 rsel;
+
+	ret = of_property_read_u32(dev.of_node, "trickle-resistor-ohms", &sp_rtc.ohms);
+	if (ret)
+		return;
+
+	switch (sp_rtc.ohms) {
+	case 2000:
+		rsel = BAT_CHARGE_RSEL_2K_OHM;
+		break;
+	case 250:
+		rsel = BAT_CHARGE_RSEL_250_OHM;
+		break;
+	case 50:
+		rsel = BAT_CHARGE_RSEL_50_OHM;
+		break;
+	case 0:
+		rsel = BAT_CHARGE_RSEL_0_OHM;
+		break;
+	default:
+		return;
+	}
+
+	writel(BAT_CHARGE_RSEL_MASK | rsel, sp_rtc.base + RTC_BATTERY_CTRL);
+
+	ret = of_property_read_bool(dev.of_node, "trickle-diode-disable");
+	if (ret)
+		writel(BAT_CHARGE_DSEL_MASK | BAT_CHARGE_DSEL_OFF, sp_rtc.base + RTC_BATTERY_CTRL);
+	else
+		writel(BAT_CHARGE_DSEL_MASK | BAT_CHARGE_DSEL_ON, sp_rtc.base + RTC_BATTERY_CTRL);
+
+	writel(BAT_CHARGE_EN_MASK | BAT_CHARGE_EN, sp_rtc.base + RTC_BATTERY_CTRL);
+}
+
+static int sp_rtc_probe(struct platform_device *plat_dev)
+{
+	struct rtc_device *rtc;
+	struct resource *res;
+	const struct rtc_class_ops *rtc_ops;
+	void __iomem *reg_base;
+	int ret, irq;
+
+	memset(&sp_rtc, 0, sizeof(sp_rtc));
+
+	// find and map our resources
+	res = platform_get_resource_byname(plat_dev, IORESOURCE_MEM, RTC_REG_NAME);
+
+	if (res) {
+		dev_dbg(&plat_dev->dev, "res = 0x%x\n", res->start);
+
+		reg_base = devm_ioremap_resource(&plat_dev->dev, res);
+		if (IS_ERR(reg_base)) {
+			dev_err(&plat_dev->dev, "%s devm_ioremap_resource fail\n", RTC_REG_NAME);
+			return PTR_ERR(reg_base);
+		}
+
+		dev_dbg(&plat_dev->dev, "reg_base = 0x%lx\n", (unsigned long)reg_base);
+	}
+
+	sp_rtc.base = reg_base;
+	rtc_ops = &sp_rtc_ops;
+
+	// Keep RTC from system reset
+	writel(DIS_SYS_RST_RTC_MASK | DIS_SYS_RST_RTC, sp_rtc.base + RTC_CTRL);
+
+	// request irq
+	irq = platform_get_irq(plat_dev, 0);
+	if (irq < 0) {
+		dev_err(&plat_dev->dev, "platform_get_irq failed\n");
+		irq = IRQ_NOTCONNECTED;
+	}
+
+	ret = devm_request_irq(&plat_dev->dev, irq, rtc_irq_handler,
+					IRQF_TRIGGER_RISING, "rtc irq", plat_dev);
+	if (ret) {
+		dev_err(&plat_dev->dev, "devm_request_irq failed: %d\n", ret);
+		return ret;
+	}
+
+	// Setup trickle charger
+	if (plat_dev->dev.of_node)
+		sp_rtc_set_trickle_charger(plat_dev->dev);
+
+	// reset
+	sp_rtc.rstc = devm_reset_control_get_exclusive(&plat_dev->dev, NULL);
+	if (IS_ERR(sp_rtc.rstc)) {
+		ret = dev_err_probe(&plat_dev->dev, PTR_ERR(sp_rtc.rstc),
+					    "failed to retrieve reset controller\n");
+		return PTR_ERR(sp_rtc.rstc);
+	}
+
+	// clk
+	sp_rtc.rtcclk = devm_clk_get(&plat_dev->dev, NULL);
+	if (IS_ERR(sp_rtc.rtcclk)) {
+		dev_err(&plat_dev->dev, "devm_clk_get fail\n");
+		return PTR_ERR(sp_rtc.rtcclk);
+	}
+
+	ret = reset_control_deassert(sp_rtc.rstc);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(sp_rtc.rtcclk);
+	if (ret)
+		return ret;
+
+	device_init_wakeup(&plat_dev->dev, 1);
+
+	rtc = devm_rtc_allocate_device(&plat_dev->dev);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
+	rtc->range_max = U32_MAX;
+	rtc->range_min = 0;
+	rtc->ops = rtc_ops;
+
+	ret = devm_rtc_register_device(rtc);
+	if (ret)
+		goto free_reset_assert_clk;
+
+	platform_set_drvdata(plat_dev, rtc);
+	dev_info(&plat_dev->dev, "sp7021-rtc loaded\n");
+
+	return 0;
+
+free_reset_assert_clk:
+	reset_control_assert(sp_rtc.rstc);
+	clk_disable_unprepare(sp_rtc.rtcclk);
+
+	return ret;
+}
+
+static int sp_rtc_remove(struct platform_device *plat_dev)
+{
+	reset_control_assert(sp_rtc.rstc);
+	clk_disable_unprepare(sp_rtc.rtcclk);
+
+	return 0;
+}
+
+static const struct of_device_id sp_rtc_of_match[] = {
+	{ .compatible = "sunplus,sp7021-rtc" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sp_rtc_of_match);
+
+static struct platform_driver sp_rtc_driver = {
+	.probe   = sp_rtc_probe,
+	.remove  = sp_rtc_remove,
+	.suspend = sp_rtc_suspend,
+	.resume  = sp_rtc_resume,
+	.driver  = {
+		.name = "sp7021-rtc",
+		.owner = THIS_MODULE,
+		.of_match_table = sp_rtc_of_match,
+	},
+};
+module_platform_driver(sp_rtc_driver);
+
+MODULE_AUTHOR("Vincent Shih <vincent.shih@sunplus.com>");
+MODULE_DESCRIPTION("Sunplus RTC driver");
+MODULE_LICENSE("GPL v2");
+
-- 
2.7.4