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path: root/drivers/rtc/rtc-pcf8523.c
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Diffstat (limited to 'drivers/rtc/rtc-pcf8523.c')
-rw-r--r--drivers/rtc/rtc-pcf8523.c394
1 files changed, 394 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
new file mode 100644
index 000000000..57d351dfe
--- /dev/null
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Avionic Design GmbH
+ */
+
+#include <linux/bcd.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/of.h>
+
+#define DRIVER_NAME "rtc-pcf8523"
+
+#define REG_CONTROL1 0x00
+#define REG_CONTROL1_CAP_SEL (1 << 7)
+#define REG_CONTROL1_STOP (1 << 5)
+
+#define REG_CONTROL3 0x02
+#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
+#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
+#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
+#define REG_CONTROL3_PM_MASK 0xe0
+#define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */
+
+#define REG_SECONDS 0x03
+#define REG_SECONDS_OS (1 << 7)
+
+#define REG_MINUTES 0x04
+#define REG_HOURS 0x05
+#define REG_DAYS 0x06
+#define REG_WEEKDAYS 0x07
+#define REG_MONTHS 0x08
+#define REG_YEARS 0x09
+
+#define REG_OFFSET 0x0e
+#define REG_OFFSET_MODE BIT(7)
+
+static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
+{
+ struct i2c_msg msgs[2];
+ u8 value = 0;
+ int err;
+
+ msgs[0].addr = client->addr;
+ msgs[0].flags = 0;
+ msgs[0].len = sizeof(reg);
+ msgs[0].buf = &reg;
+
+ msgs[1].addr = client->addr;
+ msgs[1].flags = I2C_M_RD;
+ msgs[1].len = sizeof(value);
+ msgs[1].buf = &value;
+
+ err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (err < 0)
+ return err;
+
+ *valuep = value;
+
+ return 0;
+}
+
+static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
+{
+ u8 buffer[2] = { reg, value };
+ struct i2c_msg msg;
+ int err;
+
+ msg.addr = client->addr;
+ msg.flags = 0;
+ msg.len = sizeof(buffer);
+ msg.buf = buffer;
+
+ err = i2c_transfer(client->adapter, &msg, 1);
+ if (err < 0)
+ return err;
+
+ return 0;
+}
+
+static int pcf8523_voltage_low(struct i2c_client *client)
+{
+ u8 value;
+ int err;
+
+ err = pcf8523_read(client, REG_CONTROL3, &value);
+ if (err < 0)
+ return err;
+
+ return !!(value & REG_CONTROL3_BLF);
+}
+
+static int pcf8523_load_capacitance(struct i2c_client *client)
+{
+ u32 load;
+ u8 value;
+ int err;
+
+ err = pcf8523_read(client, REG_CONTROL1, &value);
+ if (err < 0)
+ return err;
+
+ load = 12500;
+ of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads",
+ &load);
+
+ switch (load) {
+ default:
+ dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 12500",
+ load);
+ fallthrough;
+ case 12500:
+ value |= REG_CONTROL1_CAP_SEL;
+ break;
+ case 7000:
+ value &= ~REG_CONTROL1_CAP_SEL;
+ break;
+ }
+
+ err = pcf8523_write(client, REG_CONTROL1, value);
+
+ return err;
+}
+
+static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
+{
+ u8 value;
+ int err;
+
+ err = pcf8523_read(client, REG_CONTROL3, &value);
+ if (err < 0)
+ return err;
+
+ value = (value & ~REG_CONTROL3_PM_MASK) | pm;
+
+ err = pcf8523_write(client, REG_CONTROL3, value);
+ if (err < 0)
+ return err;
+
+ return 0;
+}
+
+static int pcf8523_stop_rtc(struct i2c_client *client)
+{
+ u8 value;
+ int err;
+
+ err = pcf8523_read(client, REG_CONTROL1, &value);
+ if (err < 0)
+ return err;
+
+ value |= REG_CONTROL1_STOP;
+
+ err = pcf8523_write(client, REG_CONTROL1, value);
+ if (err < 0)
+ return err;
+
+ return 0;
+}
+
+static int pcf8523_start_rtc(struct i2c_client *client)
+{
+ u8 value;
+ int err;
+
+ err = pcf8523_read(client, REG_CONTROL1, &value);
+ if (err < 0)
+ return err;
+
+ value &= ~REG_CONTROL1_STOP;
+
+ err = pcf8523_write(client, REG_CONTROL1, value);
+ if (err < 0)
+ return err;
+
+ return 0;
+}
+
+static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ u8 start = REG_SECONDS, regs[7];
+ struct i2c_msg msgs[2];
+ int err;
+
+ err = pcf8523_voltage_low(client);
+ if (err < 0) {
+ return err;
+ } else if (err > 0) {
+ dev_err(dev, "low voltage detected, time is unreliable\n");
+ return -EINVAL;
+ }
+
+ msgs[0].addr = client->addr;
+ msgs[0].flags = 0;
+ msgs[0].len = 1;
+ msgs[0].buf = &start;
+
+ msgs[1].addr = client->addr;
+ msgs[1].flags = I2C_M_RD;
+ msgs[1].len = sizeof(regs);
+ msgs[1].buf = regs;
+
+ err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (err < 0)
+ return err;
+
+ if (regs[0] & REG_SECONDS_OS)
+ return -EINVAL;
+
+ tm->tm_sec = bcd2bin(regs[0] & 0x7f);
+ tm->tm_min = bcd2bin(regs[1] & 0x7f);
+ tm->tm_hour = bcd2bin(regs[2] & 0x3f);
+ tm->tm_mday = bcd2bin(regs[3] & 0x3f);
+ tm->tm_wday = regs[4] & 0x7;
+ tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
+ tm->tm_year = bcd2bin(regs[6]) + 100;
+
+ return 0;
+}
+
+static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct i2c_msg msg;
+ u8 regs[8];
+ int err;
+
+ /*
+ * The hardware can only store values between 0 and 99 in it's YEAR
+ * register (with 99 overflowing to 0 on increment).
+ * After 2100-02-28 we could start interpreting the year to be in the
+ * interval [2100, 2199], but there is no path to switch in a smooth way
+ * because the chip handles YEAR=0x00 (and the out-of-spec
+ * YEAR=0xa0) as a leap year, but 2100 isn't.
+ */
+ if (tm->tm_year < 100 || tm->tm_year >= 200)
+ return -EINVAL;
+
+ err = pcf8523_stop_rtc(client);
+ if (err < 0)
+ return err;
+
+ regs[0] = REG_SECONDS;
+ /* This will purposely overwrite REG_SECONDS_OS */
+ regs[1] = bin2bcd(tm->tm_sec);
+ regs[2] = bin2bcd(tm->tm_min);
+ regs[3] = bin2bcd(tm->tm_hour);
+ regs[4] = bin2bcd(tm->tm_mday);
+ regs[5] = tm->tm_wday;
+ regs[6] = bin2bcd(tm->tm_mon + 1);
+ regs[7] = bin2bcd(tm->tm_year - 100);
+
+ msg.addr = client->addr;
+ msg.flags = 0;
+ msg.len = sizeof(regs);
+ msg.buf = regs;
+
+ err = i2c_transfer(client->adapter, &msg, 1);
+ if (err < 0) {
+ /*
+ * If the time cannot be set, restart the RTC anyway. Note
+ * that errors are ignored if the RTC cannot be started so
+ * that we have a chance to propagate the original error.
+ */
+ pcf8523_start_rtc(client);
+ return err;
+ }
+
+ return pcf8523_start_rtc(client);
+}
+
+#ifdef CONFIG_RTC_INTF_DEV
+static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
+ unsigned long arg)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ int ret;
+
+ switch (cmd) {
+ case RTC_VL_READ:
+ ret = pcf8523_voltage_low(client);
+ if (ret < 0)
+ return ret;
+ if (ret)
+ ret = RTC_VL_BACKUP_LOW;
+
+ return put_user(ret, (unsigned int __user *)arg);
+
+ default:
+ return -ENOIOCTLCMD;
+ }
+}
+#else
+#define pcf8523_rtc_ioctl NULL
+#endif
+
+static int pcf8523_rtc_read_offset(struct device *dev, long *offset)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ int err;
+ u8 value;
+ s8 val;
+
+ err = pcf8523_read(client, REG_OFFSET, &value);
+ if (err < 0)
+ return err;
+
+ /* sign extend the 7-bit offset value */
+ val = value << 1;
+ *offset = (value & REG_OFFSET_MODE ? 4069 : 4340) * (val >> 1);
+
+ return 0;
+}
+
+static int pcf8523_rtc_set_offset(struct device *dev, long offset)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ long reg_m0, reg_m1;
+ u8 value;
+
+ reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L);
+ reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L);
+
+ if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset))
+ value = reg_m0 & 0x7f;
+ else
+ value = (reg_m1 & 0x7f) | REG_OFFSET_MODE;
+
+ return pcf8523_write(client, REG_OFFSET, value);
+}
+
+static const struct rtc_class_ops pcf8523_rtc_ops = {
+ .read_time = pcf8523_rtc_read_time,
+ .set_time = pcf8523_rtc_set_time,
+ .ioctl = pcf8523_rtc_ioctl,
+ .read_offset = pcf8523_rtc_read_offset,
+ .set_offset = pcf8523_rtc_set_offset,
+};
+
+static int pcf8523_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct rtc_device *rtc;
+ int err;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ err = pcf8523_load_capacitance(client);
+ if (err < 0)
+ dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
+ err);
+
+ err = pcf8523_set_pm(client, 0);
+ if (err < 0)
+ return err;
+
+ rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
+ &pcf8523_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ return 0;
+}
+
+static const struct i2c_device_id pcf8523_id[] = {
+ { "pcf8523", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, pcf8523_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id pcf8523_of_match[] = {
+ { .compatible = "nxp,pcf8523" },
+ { .compatible = "microcrystal,rv8523" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, pcf8523_of_match);
+#endif
+
+static struct i2c_driver pcf8523_driver = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = of_match_ptr(pcf8523_of_match),
+ },
+ .probe = pcf8523_probe,
+ .id_table = pcf8523_id,
+};
+module_i2c_driver(pcf8523_driver);
+
+MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
+MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
+MODULE_LICENSE("GPL v2");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-01 01:00:30 +0000