1 files changed, 317 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-pcf8583.c b/drivers/rtc/rtc-pcf8583.c
new file mode 100644
index 000000000..87074d178
--- /dev/null
+++ b/drivers/rtc/rtc-pcf8583.c
@@ -0,0 +1,317 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  drivers/rtc/rtc-pcf8583.c
+ *
+ *  Copyright (C) 2000 Russell King
+ *  Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix
+ *
+ *  Driver for PCF8583 RTC & RAM chip
+ *
+ *  Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
+ */
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/rtc.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/bcd.h>
+
+struct rtc_mem {
+	unsigned int	loc;
+	unsigned int	nr;
+	unsigned char	*data;
+};
+
+struct pcf8583 {
+	struct rtc_device *rtc;
+	unsigned char ctrl;
+};
+
+#define CTRL_STOP	0x80
+#define CTRL_HOLD	0x40
+#define CTRL_32KHZ	0x00
+#define CTRL_MASK	0x08
+#define CTRL_ALARMEN	0x04
+#define CTRL_ALARM	0x02
+#define CTRL_TIMER	0x01
+
+
+static struct i2c_driver pcf8583_driver;
+
+#define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
+#define set_ctrl(x, v) get_ctrl(x) = v
+
+#define CMOS_YEAR	(64 + 128)
+#define CMOS_CHECKSUM	(63)
+
+static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
+{
+	unsigned char buf[8], addr[1] = { 1 };
+	struct i2c_msg msgs[2] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 1,
+			.buf = addr,
+		}, {
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = 6,
+			.buf = buf,
+		}
+	};
+	int ret;
+
+	memset(buf, 0, sizeof(buf));
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret == 2) {
+		dt->tm_year = buf[4] >> 6;
+		dt->tm_wday = buf[5] >> 5;
+
+		buf[4] &= 0x3f;
+		buf[5] &= 0x1f;
+
+		dt->tm_sec = bcd2bin(buf[1]);
+		dt->tm_min = bcd2bin(buf[2]);
+		dt->tm_hour = bcd2bin(buf[3]);
+		dt->tm_mday = bcd2bin(buf[4]);
+		dt->tm_mon = bcd2bin(buf[5]) - 1;
+	}
+
+	return ret == 2 ? 0 : -EIO;
+}
+
+static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
+{
+	unsigned char buf[8];
+	int ret, len = 6;
+
+	buf[0] = 0;
+	buf[1] = get_ctrl(client) | 0x80;
+	buf[2] = 0;
+	buf[3] = bin2bcd(dt->tm_sec);
+	buf[4] = bin2bcd(dt->tm_min);
+	buf[5] = bin2bcd(dt->tm_hour);
+
+	if (datetoo) {
+		len = 8;
+		buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
+		buf[7] = bin2bcd(dt->tm_mon + 1)  | (dt->tm_wday << 5);
+	}
+
+	ret = i2c_master_send(client, (char *)buf, len);
+	if (ret != len)
+		return -EIO;
+
+	buf[1] = get_ctrl(client);
+	ret = i2c_master_send(client, (char *)buf, 2);
+
+	return ret == 2 ? 0 : -EIO;
+}
+
+static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
+{
+	*ctrl = get_ctrl(client);
+	return 0;
+}
+
+static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
+{
+	unsigned char buf[2];
+
+	buf[0] = 0;
+	buf[1] = *ctrl;
+	set_ctrl(client, *ctrl);
+
+	return i2c_master_send(client, (char *)buf, 2);
+}
+
+static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
+{
+	unsigned char addr[1];
+	struct i2c_msg msgs[2] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 1,
+			.buf = addr,
+		}, {
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = mem->nr,
+			.buf = mem->data,
+		}
+	};
+
+	if (mem->loc < 8)
+		return -EINVAL;
+
+	addr[0] = mem->loc;
+
+	return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
+}
+
+static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
+{
+	unsigned char buf[9];
+	int ret;
+
+	if (mem->loc < 8 || mem->nr > 8)
+		return -EINVAL;
+
+	buf[0] = mem->loc;
+	memcpy(buf + 1, mem->data, mem->nr);
+
+	ret = i2c_master_send(client, buf, mem->nr + 1);
+	return ret == mem->nr + 1 ? 0 : -EIO;
+}
+
+static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	unsigned char ctrl, year[2];
+	struct rtc_mem mem = {
+		.loc = CMOS_YEAR,
+		.nr = sizeof(year),
+		.data = year
+	};
+	int real_year, year_offset, err;
+
+	/*
+	 * Ensure that the RTC is running.
+	 */
+	pcf8583_get_ctrl(client, &ctrl);
+	if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
+		unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
+
+		dev_warn(dev, "resetting control %02x -> %02x\n",
+			ctrl, new_ctrl);
+
+		err = pcf8583_set_ctrl(client, &new_ctrl);
+		if (err < 0)
+			return err;
+	}
+
+	if (pcf8583_get_datetime(client, tm) ||
+	    pcf8583_read_mem(client, &mem))
+		return -EIO;
+
+	real_year = year[0];
+
+	/*
+	 * The RTC year holds the LSB two bits of the current
+	 * year, which should reflect the LSB two bits of the
+	 * CMOS copy of the year.  Any difference indicates
+	 * that we have to correct the CMOS version.
+	 */
+	year_offset = tm->tm_year - (real_year & 3);
+	if (year_offset < 0)
+		/*
+		 * RTC year wrapped.  Adjust it appropriately.
+		 */
+		year_offset += 4;
+
+	tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
+
+	return 0;
+}
+
+static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	unsigned char year[2], chk;
+	struct rtc_mem cmos_year  = {
+		.loc = CMOS_YEAR,
+		.nr = sizeof(year),
+		.data = year
+	};
+	struct rtc_mem cmos_check = {
+		.loc = CMOS_CHECKSUM,
+		.nr = 1,
+		.data = &chk
+	};
+	unsigned int proper_year = tm->tm_year + 1900;
+	int ret;
+
+	/*
+	 * The RTC's own 2-bit year must reflect the least
+	 * significant two bits of the CMOS year.
+	 */
+
+	ret = pcf8583_set_datetime(client, tm, 1);
+	if (ret)
+		return ret;
+
+	ret = pcf8583_read_mem(client, &cmos_check);
+	if (ret)
+		return ret;
+
+	ret = pcf8583_read_mem(client, &cmos_year);
+	if (ret)
+		return ret;
+
+	chk -= year[1] + year[0];
+
+	year[1] = proper_year / 100;
+	year[0] = proper_year % 100;
+
+	chk += year[1] + year[0];
+
+	ret = pcf8583_write_mem(client, &cmos_year);
+
+	if (ret)
+		return ret;
+
+	ret = pcf8583_write_mem(client, &cmos_check);
+
+	return ret;
+}
+
+static const struct rtc_class_ops pcf8583_rtc_ops = {
+	.read_time	= pcf8583_rtc_read_time,
+	.set_time	= pcf8583_rtc_set_time,
+};
+
+static int pcf8583_probe(struct i2c_client *client)
+{
+	struct pcf8583 *pcf8583;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
+				GFP_KERNEL);
+	if (!pcf8583)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, pcf8583);
+
+	pcf8583->rtc = devm_rtc_device_register(&client->dev,
+				pcf8583_driver.driver.name,
+				&pcf8583_rtc_ops, THIS_MODULE);
+
+	return PTR_ERR_OR_ZERO(pcf8583->rtc);
+}
+
+static const struct i2c_device_id pcf8583_id[] = {
+	{ "pcf8583", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, pcf8583_id);
+
+static struct i2c_driver pcf8583_driver = {
+	.driver = {
+		.name	= "pcf8583",
+	},
+	.probe_new	= pcf8583_probe,
+	.id_table	= pcf8583_id,
+};
+
+module_i2c_driver(pcf8583_driver);
+
+MODULE_AUTHOR("Russell King");
+MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
+MODULE_LICENSE("GPL");