[PATCH v2 1/6] rtc: ls2x: Add support for the Loongson-2K/LS7A RTC

WANG Xuerui
2021-05-05T17:27:07Z

This RTC module is integrated into the Loongson-2K SoC and the LS7A
bridge chip. This version is almost entirely rewritten to make use of
current kernel API.

Signed-off-by: Huacai Chen <chenhuacai@kernel.org>
Signed-off-by: WANG Xuerui <git@xen0n.name>
Tested-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
drivers/rtc/Kconfig | 11 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-ls2x.c | 225 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 237 insertions(+)
create mode 100644 drivers/rtc/rtc-ls2x.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d8c13fded164..55beede68829 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1304,6 +1304,17 @@ config RTC_DRV_NTXEC
embedded controller found in certain e-book readers designed by the
original design manufacturer Netronix.

+config RTC_DRV_LS2X
+ tristate "Loongson LS2X RTC"
+ depends on MACH_LOONGSON64 || COMPILE_TEST
+ select REGMAP_MMIO
+ help
+ If you say yes here you get support for the RTC on the Loongson-2K
+ SoC and LS7A bridge, which first appeared on the Loongson-2H.
+
+ This driver can also be built as a module. If so, the module
+ will be called rtc-ls2x.
+
comment "on-CPU RTC drivers"

config RTC_DRV_ASM9260
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 2dd0dd956b0e..6042ff1e73b7 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -81,6 +81,7 @@ obj-$(CONFIG_RTC_DRV_LOONGSON1) += rtc-ls1x.o
obj-$(CONFIG_RTC_DRV_LP8788) += rtc-lp8788.o
obj-$(CONFIG_RTC_DRV_LPC24XX) += rtc-lpc24xx.o
obj-$(CONFIG_RTC_DRV_LPC32XX) += rtc-lpc32xx.o
+obj-$(CONFIG_RTC_DRV_LS2X) += rtc-ls2x.o
obj-$(CONFIG_RTC_DRV_M41T80) += rtc-m41t80.o
obj-$(CONFIG_RTC_DRV_M41T93) += rtc-m41t93.o
obj-$(CONFIG_RTC_DRV_M41T94) += rtc-m41t94.o
diff --git a/drivers/rtc/rtc-ls2x.c b/drivers/rtc/rtc-ls2x.c
new file mode 100644
index 000000000000..8eddb0316b3b
--- /dev/null
+++ b/drivers/rtc/rtc-ls2x.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Loongson-2K/7A RTC driver
+ *
+ * Based on the out-of-tree Loongson-2H RTC driver for Linux 2.6.32, by
+ * Shaozong Liu <liushaozong@loongson.cn>.
+ *
+ * Maintained out-of-tree by Huacai Chen <chenhuacai@kernel.org>.
+ *
+ * Rewritten for mainline by WANG Xuerui <git@xen0n.name>.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+#include <linux/spinlock.h>
+
+#define TOY_TRIM_REG 0x20
+#define TOY_WRITE0_REG 0x24
+#define TOY_WRITE1_REG 0x28
+#define TOY_READ0_REG 0x2c
+#define TOY_READ1_REG 0x30
+#define TOY_MATCH0_REG 0x34
+#define TOY_MATCH1_REG 0x38
+#define TOY_MATCH2_REG 0x3c
+#define RTC_CTRL_REG 0x40
+#define RTC_TRIM_REG 0x60
+#define RTC_WRITE0_REG 0x64
+#define RTC_READ0_REG 0x68
+#define RTC_MATCH0_REG 0x6c
+#define RTC_MATCH1_REG 0x70
+#define RTC_MATCH2_REG 0x74
+
+#define TOY_MON GENMASK(31, 26)
+#define TOY_MON_SHIFT 26
+#define TOY_DAY GENMASK(25, 21)
+#define TOY_DAY_SHIFT 21
+#define TOY_HOUR GENMASK(20, 16)
+#define TOY_HOUR_SHIFT 16
+#define TOY_MIN GENMASK(15, 10)
+#define TOY_MIN_SHIFT 10
+#define TOY_SEC GENMASK(9, 4)
+#define TOY_SEC_SHIFT 4
+#define TOY_MSEC GENMASK(3, 0)
+#define TOY_MSEC_SHIFT 0
+
+struct ls2x_rtc_priv {
+ struct regmap *regmap;
+ spinlock_t lock;
+};
+
+static const struct regmap_config ls2x_rtc_regmap_config = {
+ .reg_bits = 32,
+ .val_bits = 32,
+ .reg_stride = 4,
+};
+
+struct ls2x_rtc_regs {
+ u32 reg0;
+ u32 reg1;
+};
+
+static inline void ls2x_rtc_regs_to_time(struct ls2x_rtc_regs *regs,
+ struct rtc_time *tm)
+{
+ tm->tm_year = regs->reg1;
+ tm->tm_sec = (regs->reg0 & TOY_SEC) >> TOY_SEC_SHIFT;
+ tm->tm_min = (regs->reg0 & TOY_MIN) >> TOY_MIN_SHIFT;
+ tm->tm_hour = (regs->reg0 & TOY_HOUR) >> TOY_HOUR_SHIFT;
+ tm->tm_mday = (regs->reg0 & TOY_DAY) >> TOY_DAY_SHIFT;
+ tm->tm_mon = ((regs->reg0 & TOY_MON) >> TOY_MON_SHIFT) - 1;
+}
+
+static inline void ls2x_rtc_time_to_regs(struct rtc_time *tm,
+ struct ls2x_rtc_regs *regs)
+{
+ regs->reg0 = (tm->tm_sec << TOY_SEC_SHIFT) & TOY_SEC;
+ regs->reg0 |= (tm->tm_min << TOY_MIN_SHIFT) & TOY_MIN;
+ regs->reg0 |= (tm->tm_hour << TOY_HOUR_SHIFT) & TOY_HOUR;
+ regs->reg0 |= (tm->tm_mday << TOY_DAY_SHIFT) & TOY_DAY;
+ regs->reg0 |= ((tm->tm_mon + 1) << TOY_MON_SHIFT) & TOY_MON;
+ regs->reg1 = tm->tm_year;
+}
+
+static int ls2x_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct ls2x_rtc_priv *priv = dev_get_drvdata(dev);
+ struct ls2x_rtc_regs regs;
+ int ret;
+
+ spin_lock_irq(&priv->lock);
+
+ ret = regmap_read(priv->regmap, TOY_READ1_REG, &regs.reg1);
+ if (unlikely(ret)) {
+ dev_err(dev, "Failed to read time: %d\n", ret);
+ goto fail;
+ }
+
+ ret = regmap_read(priv->regmap, TOY_READ0_REG, &regs.reg0);
+ if (unlikely(ret)) {
+ dev_err(dev, "Failed to read time: %d\n", ret);
+ goto fail;
+ }
+
+ spin_unlock_irq(&priv->lock);
+
+ ls2x_rtc_regs_to_time(&regs, tm);
+
+ return 0;
+
+fail:
+ spin_unlock_irq(&priv->lock);
+ return ret;
+}
+
+static int ls2x_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct ls2x_rtc_priv *priv = dev_get_drvdata(dev);
+ struct ls2x_rtc_regs regs;
+ int ret;
+
+ ls2x_rtc_time_to_regs(tm, &regs);
+
+ spin_lock_irq(&priv->lock);
+
+ ret = regmap_write(priv->regmap, TOY_WRITE0_REG, regs.reg0);
+ if (unlikely(ret)) {
+ dev_err(dev, "Failed to set time: %d\n", ret);
+ goto fail;
+ }
+
+ ret = regmap_write(priv->regmap, TOY_WRITE1_REG, regs.reg1);
+ if (unlikely(ret)) {
+ dev_err(dev, "Failed to set time: %d\n", ret);
+ goto fail;
+ }
+
+ spin_unlock_irq(&priv->lock);
+
+ return 0;
+
+fail:
+ spin_unlock_irq(&priv->lock);
+ return ret;
+}
+
+static struct rtc_class_ops ls2x_rtc_ops = {
+ .read_time = ls2x_rtc_read_time,
+ .set_time = ls2x_rtc_set_time,
+};
+
+static int ls2x_rtc_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct rtc_device *rtc;
+ struct ls2x_rtc_priv *priv;
+ void __iomem *regs;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (unlikely(!priv))
+ return -ENOMEM;
+
+ spin_lock_init(&priv->lock);
+ platform_set_drvdata(pdev, priv);
+
+ regs = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(regs)) {
+ ret = PTR_ERR(regs);
+ dev_err(dev, "Failed to map rtc registers: %d\n", ret);
+ return ret;
+ }
+
+ priv->regmap = devm_regmap_init_mmio(dev, regs,
+ &ls2x_rtc_regmap_config);
+ if (IS_ERR(priv->regmap)) {
+ ret = PTR_ERR(priv->regmap);
+ dev_err(dev, "Failed to init regmap: %d\n", ret);
+ return ret;
+ }
+
+ rtc = devm_rtc_allocate_device(dev);
+ if (IS_ERR(rtc)) {
+ ret = PTR_ERR(rtc);
+ dev_err(dev, "Failed to allocate rtc device: %d\n", ret);
+ return ret;
+ }
+
+ rtc->ops = &ls2x_rtc_ops;
+
+ /* Due to hardware erratum, all years multiple of 4 are considered
+ * leap year, so only years 2000 through 2099 are usable.
+ *
+ * Previous out-of-tree versions of this driver wrote tm_year directly
+ * into the year register, so epoch 2000 must be used to preserve
+ * semantics on shipped systems.
+ */
+ rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+ rtc->range_max = RTC_TIMESTAMP_END_2099;
+
+ return rtc_register_device(rtc);
+}
+
+static const struct of_device_id ls2x_rtc_of_match[] = {
+ { .compatible = "loongson,ls2x-rtc" },
+ { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ls2x_rtc_of_match);
+
+static struct platform_driver ls2x_rtc_driver = {
+ .probe = ls2x_rtc_probe,
+ .driver = {
+ .name = "ls2x-rtc",
+ .of_match_table = of_match_ptr(ls2x_rtc_of_match),
+ },
+};
+
+module_platform_driver(ls2x_rtc_driver);
+
+MODULE_DESCRIPTION("LS2X RTC driver");
+MODULE_AUTHOR("WANG Xuerui");
+MODULE_AUTHOR("Huacai Chen");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ls2x-rtc");
--
2.30.1