[RFC PATCH 3/3] clocksource/drivers: Add HiSilicon system timer driver

[Yicong Yang <yangyicong@huawei.com>]

From: Yicong Yang <yangyicong@hisilicon.com>

HiSilicon system timer is compatible with arm's generic timer
specification but is enumerated through DSDT and can use SPI/LPI
interrupt as timer interrupt. This patch adds the support
for the timer. The driver probes the device IO memory and
interrupt resources through DSDT and then reuse the codes
of the arm_arch_timer for setup and register the clockevent
device.

Example DSDT node will be like:
	Device (TIM0)
        {
            Name (_HID, "HISI03F2")  // _HID: Hardware ID
            Name (_UID, Zero)  // _UID: Unique ID
            Name (RBUF, ResourceTemplate ()
            {
                QWordMemory (ResourceConsumer, PosDecode, MinFixed, MaxFixed, NonCacheable, ReadWrite,
                    0x0000000000000000, // Granularity
                    0x0000000401170000, // Range Minimum
                    0x0000000401170fff, // Range Maximum
                    0x0000000000000000, // Translation Offset
                    0x0000000000001000, // Length
                    ,, , AddressRangeMemory, TypeStatic)
                Interrupt (ResourceConsumer, Level, ActiveHigh, Exclusive, ,, )
                {
                    0x000003C6,
                }
            })
	    Method (_CRS, 0, NotSerialized)
	    {
		Return (RBUF)
	    }
	}

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/clocksource/Kconfig          | 10 ++++
 drivers/clocksource/Makefile         |  1 +
 drivers/clocksource/timer-hisi-sys.c | 68 ++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+)
 create mode 100644 drivers/clocksource/timer-hisi-sys.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 0ba0dc4ecf06..2e43cd6e2add 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -732,4 +732,14 @@ config GOLDFISH_TIMER
 	help
 	  Support for the timer/counter of goldfish-rtc
 
+config HISI_SYS_TIMER
+	tristate "HiSilicon system timer driver"
+	depends on ARM_ARCH_TIMER && ARM64 && ACPI
+	help
+	  Support for HiSilicon system timer which used as a clockevent
+	  device.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called timer_hisi_sys.
+
 endmenu
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 368c3461dab8..39ababd0d4dd 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -89,3 +89,4 @@ obj-$(CONFIG_MSC313E_TIMER)		+= timer-msc313e.o
 obj-$(CONFIG_GOLDFISH_TIMER)		+= timer-goldfish.o
 obj-$(CONFIG_GXP_TIMER)			+= timer-gxp.o
 obj-$(CONFIG_CLKSRC_LOONGSON1_PWM)	+= timer-loongson1-pwm.o
+obj-$(CONFIG_HISI_SYS_TIMER)		+= timer-hisi-sys.o
diff --git a/drivers/clocksource/timer-hisi-sys.c b/drivers/clocksource/timer-hisi-sys.c
new file mode 100644
index 000000000000..1ef39d97e83d
--- /dev/null
+++ b/drivers/clocksource/timer-hisi-sys.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for HiSilicon system timer driver.
+ *
+ * The device is fully compatible with ARM's Generic Timer specification.
+ * The device is enumerated through DSDT rather than GTDT and can use
+ * LPI interrupt besides SPI.
+ *
+ * Copyright (c) 2023 HiSilicon Technologies Co., Ltd.
+ * Author: Yicong Yang <yangyicong@hisilicon.com>
+ */
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/units.h>
+
+#include <clocksource/arm_arch_timer.h>
+
+#define DRV_NAME	"hisi_sys_timer"
+
+#define CNTFRQ		0x10
+
+static const struct acpi_device_id hisi_sys_timer_acpi_ids[] = {
+	{ "HISI03F2", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, hisi_sys_timer_acpi_ids);
+
+static int hisi_sys_timer_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	void __iomem *iobase;
+	int ret, irq;
+	u32 freq;
+
+	iobase = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(iobase))
+		return PTR_ERR(iobase);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq <= 0)
+		return dev_err_probe(dev, ret, "failed to get interrupt\n");
+
+	ret = arch_timer_mem_register(iobase, irq, false, DRV_NAME);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to register timer\n");
+
+	freq = readl_relaxed(iobase + CNTFRQ);
+	dev_info(dev, "%s works at %ldMHz\n", DRV_NAME, freq / HZ_PER_MHZ);
+	return 0;
+}
+
+static struct platform_driver hisi_sys_timer_driver = {
+	.probe = hisi_sys_timer_probe,
+	.driver = {
+		.name = DRV_NAME,
+		.acpi_match_table = hisi_sys_timer_acpi_ids,
+	},
+};
+module_platform_driver(hisi_sys_timer_driver);
+
+MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
+MODULE_DESCRIPTION("HiSilicon system timer driver");
+MODULE_LICENSE("GPL");
-- 
2.24.0