[PATCH v3 0/6] rtc: ls2x: Add support for the Loongson-2K/LS7A RTC

[PATCH v3 0/6] rtc: ls2x: Add support for the Loongson-2K/LS7A RTC

[WANG Xuerui]

It has been a while since v1 of this series was sent (2020-09);
apparently, I did not have enough time or resource figuring out the exact
difference between rtc-ls1x and rtc-ls2x to see if the two can in fact be
merged, even today. Sorry for the long delay!

According to the manuals, though, the initialization sequence and
bitfield descriptions look certainly different, so I'm a bit wary about
just going ahead and merging these. Per Tiezhu's suggestion in the
previous thread, I'm just re-submitting this series with tags collected
and Huacai's e-mail address updated. If anyone (probably Loongson guys?)
could provide more information regarding the possible merger of rtc-ls1x
and rtc-ls2x, that would be great.

This patch series adds support for the RTC module found on various
Loongson systems with the Loongson-2K SoC or the LS7A bridge chip.
The driver is rewritten from an out-of-tree version to meet mainline
standards. I write kernel code as a hobby, though, so there might still
be overlooked issues. Any suggestions are welcome.

Note that, the Loongson-2K platform was upstreamed after v1 of this
series, so v2 additionally contains enablement for it. I'm unable to
test with my 2K board now, however, so Loongson guys, please test this
series again on your collection of LS7A and 2K systems, thanks!

This patch is based on next-20210505, since we're in the middle of merge
window. Should apply cleanly after the merge window closes, though.

v3:
- Fixed compile error not discovered after rebase (blame sleep
  deprivation)
- Tested on Loongson-3A4000 (still need testing on Loongson-2K)

v2:
- Rebased on top of latest linux-next
- Updated Huacai's e-mail address to the kernel.org one
- Added collected tags
- Added adaptation for newly upstreamed Loongson-2K platforms

WANG Xuerui (6):
  rtc: ls2x: Add support for the Loongson-2K/LS7A RTC
  dt-bindings: rtc: Add bindings for LS2X RTC
  MIPS: Loongson64: DTS: Add RTC support to LS7A
  MIPS: Loongson: Enable LS2X RTC in loongson3_defconfig
  MIPS: Loongson64: DTS: Add RTC support to Loongson-2K
  MIPS: Loongson: Enable LS2X RTC in loongson2k_defconfig

 .../devicetree/bindings/rtc/trivial-rtc.yaml  |   2 +
 .../boot/dts/loongson/loongson64-2k1000.dtsi  |   5 +
 arch/mips/boot/dts/loongson/ls7a-pch.dtsi     |   5 +
 arch/mips/configs/loongson2k_defconfig        |   1 +
 arch/mips/configs/loongson3_defconfig         |   1 +
 drivers/rtc/Kconfig                           |  11 +
 drivers/rtc/Makefile                          |   1 +
 drivers/rtc/rtc-ls2x.c                        | 225 ++++++++++++++++++
 8 files changed, 251 insertions(+)
 create mode 100644 drivers/rtc/rtc-ls2x.c


base-commit: 29955e0289b3255c5f609a7564a0f0bb4ae35c7a
-- 
2.30.1

[PATCH v3 1/6] rtc: ls2x: Add support for the Loongson-2K/LS7A RTC

[WANG Xuerui]

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>
---
 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..6508a87bdb31
--- /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 devm_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

[PATCH v3 2/6] dt-bindings: rtc: Add bindings for LS2X RTC

[WANG Xuerui]

Document the binding for the LS2X RTC block found on the Loongson-2K SoC
and the LS7A bridge, originally appearing on the Loongson-2H.

Signed-off-by: WANG Xuerui <git@xen0n.name>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
---
 Documentation/devicetree/bindings/rtc/trivial-rtc.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml b/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml
index 7548d8714871..568aa89989fe 100644
--- a/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml
+++ b/Documentation/devicetree/bindings/rtc/trivial-rtc.yaml
@@ -42,6 +42,8 @@ properties:
       - isil,isl1218
       # Intersil ISL12022 Real-time Clock
       - isil,isl12022
+      # Loongson LS2X RTC
+      - loongson,ls2x-rtc
       # Real Time Clock Module with I2C-Bus
       - microcrystal,rv3028
       # Real Time Clock Module with I2C-Bus
-- 
2.30.1

[PATCH v3 3/6] MIPS: Loongson64: DTS: Add RTC support to LS7A

[WANG Xuerui]

The LS7A RTC module is now supported, enable it.

Signed-off-by: WANG Xuerui <git@xen0n.name>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
---
 arch/mips/boot/dts/loongson/ls7a-pch.dtsi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/mips/boot/dts/loongson/ls7a-pch.dtsi b/arch/mips/boot/dts/loongson/ls7a-pch.dtsi
index f99a7a11fded..39808e97e6e1 100644
--- a/arch/mips/boot/dts/loongson/ls7a-pch.dtsi
+++ b/arch/mips/boot/dts/loongson/ls7a-pch.dtsi
@@ -19,6 +19,11 @@ pic: interrupt-controller@10000000 {
 			#interrupt-cells = <2>;
 		};
 
+		rtc0: rtc@100d0100 {
+			compatible = "loongson,ls2x-rtc";
+			reg = <0 0x100d0100 0 0x78>;
+		};
+
 		ls7a_uart0: serial@10080000 {
 			compatible = "ns16550a";
 			reg = <0 0x10080000 0 0x100>;
-- 
2.30.1

[PATCH v3 4/6] MIPS: Loongson: Enable LS2X RTC in loongson3_defconfig

[WANG Xuerui]

This is now supported, enable for Loongson-3 systems.
Other systems are unaffected.

Signed-off-by: WANG Xuerui <git@xen0n.name>
---
 arch/mips/configs/loongson3_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/mips/configs/loongson3_defconfig b/arch/mips/configs/loongson3_defconfig
index a18609cf0e5e..b34ca534b9b6 100644
--- a/arch/mips/configs/loongson3_defconfig
+++ b/arch/mips/configs/loongson3_defconfig
@@ -325,6 +325,7 @@ CONFIG_USB_SERIAL_OPTION=m
 CONFIG_RTC_CLASS=y
 CONFIG_RTC_DRV_CMOS=y
 CONFIG_RTC_DRV_GOLDFISH=y
+CONFIG_RTC_DRV_LS2X=y
 CONFIG_DMADEVICES=y
 CONFIG_VIRTIO_PCI=y
 CONFIG_VIRTIO_BALLOON=m
-- 
2.30.1

[PATCH v3 5/6] MIPS: Loongson64: DTS: Add RTC support to Loongson-2K

[WANG Xuerui]

The Loongson-2K RTC module is now supported, enable it.

The MMIO address is unclear from the Loongson 2K1000 user manual, I took
it from Loongson's out-of-tree fork of Linux 4.19.

Signed-off-by: WANG Xuerui <git@xen0n.name>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
---
 arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi b/arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi
index 569e814def83..0f00080f77b9 100644
--- a/arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi
+++ b/arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi
@@ -52,6 +52,11 @@ package0: bus@10000000 {
 			0 0x40000000 0 0x40000000 0 0x40000000
 			0xfe 0x00000000 0xfe 0x00000000 0 0x40000000>;
 
+		rtc0: rtc@1fe07800 {
+			compatible = "loongson,ls2x-rtc";
+			reg = <0 0x1fe07800 0 0x78>;
+		};
+
 		liointc0: interrupt-controller@1fe11400 {
 			compatible = "loongson,liointc-2.0";
 			reg = <0 0x1fe11400 0 0x40>,
-- 
2.30.1

[PATCH v3 6/6] MIPS: Loongson: Enable LS2X RTC in loongson2k_defconfig

[WANG Xuerui]

This is now supported, enable for Loongson-2K systems.
Other systems are unaffected.

Signed-off-by: WANG Xuerui <git@xen0n.name>
---
 arch/mips/configs/loongson2k_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/mips/configs/loongson2k_defconfig b/arch/mips/configs/loongson2k_defconfig
index e948ca487e2d..e15f34857956 100644
--- a/arch/mips/configs/loongson2k_defconfig
+++ b/arch/mips/configs/loongson2k_defconfig
@@ -280,6 +280,7 @@ CONFIG_USB_SERIAL=m
 CONFIG_USB_SERIAL_OPTION=m
 CONFIG_RTC_CLASS=y
 CONFIG_RTC_DRV_CMOS=y
+CONFIG_RTC_DRV_LS2X=y
 CONFIG_DMADEVICES=y
 # CONFIG_CPU_HWMON is not set
 CONFIG_PM_DEVFREQ=y
-- 
2.30.1

Re: [PATCH v3 0/6] rtc: ls2x: Add support for the Loongson-2K/LS7A RTC

[Jiaxun Yang]

On Thu, May 6, 2021, at 9:04 AM, WANG Xuerui wrote:
> It has been a while since v1 of this series was sent (2020-09);
> apparently, I did not have enough time or resource figuring out the exact
> difference between rtc-ls1x and rtc-ls2x to see if the two can in fact be
> merged, even today. Sorry for the long delay!
> 
> According to the manuals, though, the initialization sequence and
> bitfield descriptions look certainly different, so I'm a bit wary about
> just going ahead and merging these. Per Tiezhu's suggestion in the
> previous thread, I'm just re-submitting this series with tags collected
> and Huacai's e-mail address updated. If anyone (probably Loongson guys?)
> could provide more information regarding the possible merger of rtc-ls1x
> and rtc-ls2x, that would be great.
> 
> This patch series adds support for the RTC module found on various
> Loongson systems with the Loongson-2K SoC or the LS7A bridge chip.
> The driver is rewritten from an out-of-tree version to meet mainline
> standards. I write kernel code as a hobby, though, so there might still
> be overlooked issues. Any suggestions are welcome.
> 
> Note that, the Loongson-2K platform was upstreamed after v1 of this
> series, so v2 additionally contains enablement for it. I'm unable to
> test with my 2K board now, however, so Loongson guys, please test this
> series again on your collection of LS7A and 2K systems, thanks!
> 
> This patch is based on next-20210505, since we're in the middle of merge
> window. Should apply cleanly after the merge window closes, though.

For whole series,
Tested-by: Jiaxun Yang <jiaxun.yang@flygoat.com> # loongson2k


> 
> v3:
> - Fixed compile error not discovered after rebase (blame sleep
>   deprivation)
> - Tested on Loongson-3A4000 (still need testing on Loongson-2K)
> 
> v2:
> - Rebased on top of latest linux-next
> - Updated Huacai's e-mail address to the kernel.org one
> - Added collected tags
> - Added adaptation for newly upstreamed Loongson-2K platforms
> 
> WANG Xuerui (6):
>   rtc: ls2x: Add support for the Loongson-2K/LS7A RTC
>   dt-bindings: rtc: Add bindings for LS2X RTC
>   MIPS: Loongson64: DTS: Add RTC support to LS7A
>   MIPS: Loongson: Enable LS2X RTC in loongson3_defconfig
>   MIPS: Loongson64: DTS: Add RTC support to Loongson-2K
>   MIPS: Loongson: Enable LS2X RTC in loongson2k_defconfig
> 
>  .../devicetree/bindings/rtc/trivial-rtc.yaml  |   2 +
>  .../boot/dts/loongson/loongson64-2k1000.dtsi  |   5 +
>  arch/mips/boot/dts/loongson/ls7a-pch.dtsi     |   5 +
>  arch/mips/configs/loongson2k_defconfig        |   1 +
>  arch/mips/configs/loongson3_defconfig         |   1 +
>  drivers/rtc/Kconfig                           |  11 +
>  drivers/rtc/Makefile                          |   1 +
>  drivers/rtc/rtc-ls2x.c                        | 225 ++++++++++++++++++
>  8 files changed, 251 insertions(+)
>  create mode 100644 drivers/rtc/rtc-ls2x.c
> 
> 
> base-commit: 29955e0289b3255c5f609a7564a0f0bb4ae35c7a
> -- 
> 2.30.1
> 
> 


-- 
- Jiaxun

Re: [PATCH v3 1/6] rtc: ls2x: Add support for the Loongson-2K/LS7A RTC

[Alexandre Belloni]

Hi,

On 06/05/2021 09:04:30+0800, WANG Xuerui wrote:
> 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>
> ---
>  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..6508a87bdb31
> --- /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;

Please use FIELD_GET

> +}
> +
> +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;

and FIELD_PREP, this should remove the need for *_SHIFT

> +	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);

What are you locking against?

> +
> +	ret = regmap_read(priv->regmap, TOY_READ1_REG, &regs.reg1);
> +	if (unlikely(ret)) {
> +		dev_err(dev, "Failed to read time: %d\n", ret);

Please avoid those error message, they are not that useful and bloat the
kernel.

> +		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);

I'm pretty sure this error message is unnecessary

> +		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);

ditto

> +		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);

This on has to be removed.

> +		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 devm_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
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com