vegman: kernel: add RTC driver for PCHC620

Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>

3 files changed, 161 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index f7bf87097a9f..ff17f64d518e 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -555,6 +555,16 @@ config RTC_DRV_PALMAS
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-palma.
 
+config RTC_DRV_PCHC620
+	tristate "PCH C620 RTC driver"
+	help
+	  If you say yes here you get support for the Intel C620 Series PCH
+	  built-in read-only RTC. This driver is not for in-system use on x86,
+	  but rather is for external access over I2C from a BMC.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-pchc620.
+
 config RTC_DRV_TPS6586X
 	tristate "TI TPS6586X RTC driver"
 	depends on MFD_TPS6586X
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 2dd0dd956b0e..4280feb0f8b7 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -112,6 +112,7 @@ obj-$(CONFIG_RTC_DRV_NTXEC)	+= rtc-ntxec.o
 obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
 obj-$(CONFIG_RTC_DRV_OPAL)	+= rtc-opal.o
 obj-$(CONFIG_RTC_DRV_PALMAS)	+= rtc-palmas.o
+obj-$(CONFIG_RTC_DRV_PCHC620)	+= rtc-pchc620.o
 obj-$(CONFIG_RTC_DRV_PCAP)	+= rtc-pcap.o
 obj-$(CONFIG_RTC_DRV_PCF2123)	+= rtc-pcf2123.o
 obj-$(CONFIG_RTC_DRV_PCF2127)	+= rtc-pcf2127.o
diff --git a/drivers/rtc/rtc-pchc620.c b/drivers/rtc/rtc-pchc620.c
new file mode 100644
index 000000000000..a944b327ca67
--- /dev/null
+++ b/drivers/rtc/rtc-pchc620.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * RTC driver for PCHC620
+ * Copyright (C) 2021 YADRO
+ */
+
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/rtc.h>
+#include <linux/bcd.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#define PCH_REG_FORCE_OFF		0x00
+#define PCH_REG_SC			0x09
+#define PCH_REG_MN			0x0a
+#define PCH_REG_HR			0x0b
+#define PCH_REG_DW			0x0c
+#define PCH_REG_DM			0x0d
+#define PCH_REG_MO			0x0e
+#define PCH_REG_YR			0x0f
+
+#define NUM_TIME_REGS   (PCH_REG_YR - PCH_REG_SC + 1)
+
+struct pch {
+	struct rtc_device *rtc;
+	struct regmap *regmap;
+};
+
+static int pchc620_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct pch *pch = i2c_get_clientdata(client);
+	unsigned char rtc_data[NUM_TIME_REGS] = {0};
+	int rc;
+
+	rc = regmap_bulk_read(pch->regmap, PCH_REG_SC, rtc_data, NUM_TIME_REGS);
+	if (rc < 0) {
+		dev_err(dev, "Fail to read time reg(%d)\n", rc);
+		return rc;
+	}
+
+	tm->tm_sec	= bcd2bin(rtc_data[0]);
+	tm->tm_min	= bcd2bin(rtc_data[1]);
+	tm->tm_hour	= bcd2bin(rtc_data[2]);
+	tm->tm_wday	= rtc_data[3];
+	tm->tm_mday	= bcd2bin(rtc_data[4]);
+	tm->tm_mon	= bcd2bin(rtc_data[5]) - 1;
+	tm->tm_year	= bcd2bin(rtc_data[6]) + 100;
+
+	return 0;
+}
+
+static ssize_t pch_force_off(struct device *dev,
+			     struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct pch *pch = i2c_get_clientdata(client);
+	unsigned long val;
+	int rc;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	if (val) {
+		/* 0x02 host force off */
+		rc = regmap_write(pch->regmap, PCH_REG_FORCE_OFF, 0x2);
+		if (rc < 0) {
+			dev_err(dev, "Fail to read time reg(%d)\n", rc);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+static DEVICE_ATTR(force_off, S_IWUSR | S_IWGRP, NULL, pch_force_off);
+
+static const struct rtc_class_ops pchc620_rtc_ops = {
+	.read_time = pchc620_rtc_read_time,
+};
+
+static const struct regmap_config pchc620_rtc_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.use_single_read = true,
+};
+
+static int pchc620_rtc_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct pch *pch;
+	int rc;
+
+	pch = devm_kzalloc(&client->dev, sizeof(*pch), GFP_KERNEL);
+	if (!pch)
+		return -ENOMEM;
+
+	pch->regmap = devm_regmap_init_i2c(client, &pchc620_rtc_regmap_config);
+	if (IS_ERR(pch->regmap)) {
+		dev_err(&client->dev, "regmap_init failed\n");
+		return PTR_ERR(pch->regmap);
+	}
+
+	i2c_set_clientdata(client, pch);
+
+	pch->rtc = devm_rtc_device_register(&client->dev, "pch-rtc",
+				&pchc620_rtc_ops, THIS_MODULE);
+	if (IS_ERR(pch->rtc))
+		return PTR_ERR(pch->rtc);
+
+	rc = sysfs_create_file(&client->dev.kobj, &dev_attr_force_off.attr);
+	if (rc)
+		return rc;
+
+	return 0;
+}
+
+static int pchc620_rtc_remove(struct i2c_client *client)
+{
+	sysfs_remove_file(&client->dev.kobj, &dev_attr_force_off.attr);
+	return 0;
+}
+
+static const struct i2c_device_id pchc620_rtc_id[] = {
+	{ "pchc620-rtc", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pchc620_rtc_id);
+
+static const struct of_device_id pchc620_rtc_of_match[] = {
+	{ .compatible = "rtc,pchc620", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, pchc620_rtc_of_match);
+
+static struct i2c_driver pchc620_rtc_driver = {
+	.driver		= {
+		.name	= "pchc620-rtc",
+		.of_match_table = pchc620_rtc_of_match,
+	},
+	.probe		= pchc620_rtc_probe,
+	.remove		= pchc620_rtc_remove,
+	.id_table	= pchc620_rtc_id,
+};
+module_i2c_driver(pchc620_rtc_driver);
+
+MODULE_DESCRIPTION("RTC PCHC620 driver");
+MODULE_AUTHOR("Ivan Mikhaylov <i.mikhaylov@yadro.com>");
+MODULE_LICENSE("GPL");