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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.c326
1 files changed, 326 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
new file mode 100644
index 00000000000..be05a645f99
--- /dev/null
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -0,0 +1,326 @@
+/*
+ * Copyright (C) 2012 Avionic Design GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#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_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
+
+struct pcf8523 {
+ struct rtc_device *rtc;
+};
+
+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_select_capacitance(struct i2c_client *client, bool high)
+{
+ u8 value;
+ int err;
+
+ err = pcf8523_read(client, REG_CONTROL1, &value);
+ if (err < 0)
+ return err;
+
+ if (!high)
+ value &= ~REG_CONTROL1_CAP_SEL;
+ else
+ value |= REG_CONTROL1_CAP_SEL;
+
+ err = pcf8523_write(client, REG_CONTROL1, value);
+ if (err < 0)
+ return err;
+
+ 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;
+
+ 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) {
+ /*
+ * If the oscillator was stopped, try to clear the flag. Upon
+ * power-up the flag is always set, but if we cannot clear it
+ * the oscillator isn't running properly for some reason. The
+ * sensible thing therefore is to return an error, signalling
+ * that the clock cannot be assumed to be correct.
+ */
+
+ regs[0] &= ~REG_SECONDS_OS;
+
+ err = pcf8523_write(client, REG_SECONDS, regs[0]);
+ if (err < 0)
+ return err;
+
+ err = pcf8523_read(client, REG_SECONDS, &regs[0]);
+ if (err < 0)
+ return err;
+
+ if (regs[0] & REG_SECONDS_OS)
+ return -EAGAIN;
+ }
+
+ 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);
+ tm->tm_year = bcd2bin(regs[6]) + 100;
+
+ return rtc_valid_tm(tm);
+}
+
+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;
+
+ err = pcf8523_stop_rtc(client);
+ if (err < 0)
+ return err;
+
+ regs[0] = REG_SECONDS;
+ 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);
+ 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);
+}
+
+static const struct rtc_class_ops pcf8523_rtc_ops = {
+ .read_time = pcf8523_rtc_read_time,
+ .set_time = pcf8523_rtc_set_time,
+};
+
+static int pcf8523_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct pcf8523 *pcf;
+ int err;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
+ if (!pcf)
+ return -ENOMEM;
+
+ err = pcf8523_select_capacitance(client, true);
+ if (err < 0)
+ return err;
+
+ err = pcf8523_set_pm(client, 0);
+ if (err < 0)
+ return err;
+
+ pcf->rtc = rtc_device_register(DRIVER_NAME, &client->dev,
+ &pcf8523_rtc_ops, THIS_MODULE);
+ if (IS_ERR(pcf->rtc))
+ return PTR_ERR(pcf->rtc);
+
+ i2c_set_clientdata(client, pcf);
+
+ return 0;
+}
+
+static int pcf8523_remove(struct i2c_client *client)
+{
+ struct pcf8523 *pcf = i2c_get_clientdata(client);
+
+ rtc_device_unregister(pcf->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" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, pcf8523_of_match);
+#endif
+
+static struct i2c_driver pcf8523_driver = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(pcf8523_of_match),
+ },
+ .probe = pcf8523_probe,
+ .remove = pcf8523_remove,
+ .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 v1.2.3-70-g09d2 (git 2.46.0) at 2024-11-23 19:53:07 +0000