--- /dev/null
+/*
+ * rtc class driver for the Maxim MAX6900 chip
+ *
+ * Author: Dale Farnsworth <dale@farnsworth.org>
+ *
+ * based on previously existing rtc class drivers
+ *
+ * 2007 (c) MontaVista, Software, Inc. This file is licensed under
+ * the terms of the GNU General Public License version 2. This program
+ * is licensed "as is" without any warranty of any kind, whether express
+ * or implied.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+
+#define DRV_NAME "max6900"
+#define DRV_VERSION "0.1"
+
+/*
+ * register indices
+ */
+#define MAX6900_REG_SC 0 /* seconds 00-59 */
+#define MAX6900_REG_MN 1 /* minutes 00-59 */
+#define MAX6900_REG_HR 2 /* hours 00-23 */
+#define MAX6900_REG_DT 3 /* day of month 00-31 */
+#define MAX6900_REG_MO 4 /* month 01-12 */
+#define MAX6900_REG_DW 5 /* day of week 1-7 */
+#define MAX6900_REG_YR 6 /* year 00-99 */
+#define MAX6900_REG_CT 7 /* control */
+#define MAX6900_REG_LEN 8
+
+#define MAX6900_REG_CT_WP (1 << 7) /* Write Protect */
+
+/*
+ * register read/write commands
+ */
+#define MAX6900_REG_CONTROL_WRITE 0x8e
+#define MAX6900_REG_BURST_READ 0xbf
+#define MAX6900_REG_BURST_WRITE 0xbe
+#define MAX6900_REG_RESERVED_READ 0x96
+
+#define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */
+
+#define MAX6900_I2C_ADDR 0xa0
+
+static unsigned short normal_i2c[] = {
+ MAX6900_I2C_ADDR >> 1,
+ I2C_CLIENT_END
+};
+
+I2C_CLIENT_INSMOD; /* defines addr_data */
+
+static int max6900_probe(struct i2c_adapter *adapter, int addr, int kind);
+
+static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf)
+{
+ u8 reg_addr[1] = { MAX6900_REG_BURST_READ };
+ struct i2c_msg msgs[2] = {
+ {
+ .addr = client->addr,
+ .flags = 0, /* write */
+ .len = sizeof(reg_addr),
+ .buf = reg_addr
+ },
+ {
+ .addr = client->addr,
+ .flags = I2C_M_RD,
+ .len = MAX6900_REG_LEN,
+ .buf = buf
+ }
+ };
+ int rc;
+
+ rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (rc != ARRAY_SIZE(msgs)) {
+ dev_err(&client->dev, "%s: register read failed\n",
+ __FUNCTION__);
+ return -EIO;
+ }
+ return 0;
+}
+
+static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf)
+{
+ u8 i2c_buf[MAX6900_REG_LEN + 1] = { MAX6900_REG_BURST_WRITE };
+ struct i2c_msg msgs[1] = {
+ {
+ .addr = client->addr,
+ .flags = 0, /* write */
+ .len = MAX6900_REG_LEN + 1,
+ .buf = i2c_buf
+ }
+ };
+ int rc;
+
+ memcpy(&i2c_buf[1], buf, MAX6900_REG_LEN);
+
+ rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+ if (rc != ARRAY_SIZE(msgs)) {
+ dev_err(&client->dev, "%s: register write failed\n",
+ __FUNCTION__);
+ return -EIO;
+ }
+ msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
+ return 0;
+}
+
+static int max6900_i2c_validate_client(struct i2c_client *client)
+{
+ u8 regs[MAX6900_REG_LEN];
+ u8 zero_mask[MAX6900_REG_LEN] = {
+ 0x80, /* seconds */
+ 0x80, /* minutes */
+ 0x40, /* hours */
+ 0xc0, /* day of month */
+ 0xe0, /* month */
+ 0xf8, /* day of week */
+ 0x00, /* year */
+ 0x7f, /* control */
+ };
+ int i;
+ int rc;
+ int reserved;
+
+ reserved = i2c_smbus_read_byte_data(client, MAX6900_REG_RESERVED_READ);
+ if (reserved != 0x07)
+ return -ENODEV;
+
+ rc = max6900_i2c_read_regs(client, regs);
+ if (rc < 0)
+ return rc;
+
+ for (i = 0; i < MAX6900_REG_LEN; ++i) {
+ if (regs[i] & zero_mask[i])
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int max6900_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)
+{
+ int rc;
+ u8 regs[MAX6900_REG_LEN];
+
+ rc = max6900_i2c_read_regs(client, regs);
+ if (rc < 0)
+ return rc;
+
+ tm->tm_sec = BCD2BIN(regs[MAX6900_REG_SC]);
+ tm->tm_min = BCD2BIN(regs[MAX6900_REG_MN]);
+ tm->tm_hour = BCD2BIN(regs[MAX6900_REG_HR] & 0x3f);
+ tm->tm_mday = BCD2BIN(regs[MAX6900_REG_DT]);
+ tm->tm_mon = BCD2BIN(regs[MAX6900_REG_MO]) - 1;
+ tm->tm_year = BCD2BIN(regs[MAX6900_REG_YR]) + 100;
+ tm->tm_wday = BCD2BIN(regs[MAX6900_REG_DW]);
+
+ return 0;
+}
+
+static int max6900_i2c_clear_write_protect(struct i2c_client *client)
+{
+ int rc;
+ rc = i2c_smbus_write_byte_data (client, MAX6900_REG_CONTROL_WRITE, 0);
+ if (rc < 0) {
+ dev_err(&client->dev, "%s: control register write failed\n",
+ __FUNCTION__);
+ return -EIO;
+ }
+ return 0;
+}
+
+static int max6900_i2c_set_time(struct i2c_client *client,
+ struct rtc_time const *tm)
+{
+ u8 regs[MAX6900_REG_LEN];
+ int rc;
+
+ rc = max6900_i2c_clear_write_protect(client);
+ if (rc < 0)
+ return rc;
+
+ regs[MAX6900_REG_SC] = BIN2BCD(tm->tm_sec);
+ regs[MAX6900_REG_MN] = BIN2BCD(tm->tm_min);
+ regs[MAX6900_REG_HR] = BIN2BCD(tm->tm_hour);
+ regs[MAX6900_REG_DT] = BIN2BCD(tm->tm_mday);
+ regs[MAX6900_REG_MO] = BIN2BCD(tm->tm_mon + 1);
+ regs[MAX6900_REG_YR] = BIN2BCD(tm->tm_year - 100);
+ regs[MAX6900_REG_DW] = BIN2BCD(tm->tm_wday);
+ regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP; /* set write protect */
+
+ rc = max6900_i2c_write_regs(client, regs);
+ if (rc < 0)
+ return rc;
+
+ return 0;
+}
+
+static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ return max6900_i2c_read_time(to_i2c_client(dev), tm);
+}
+
+static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ return max6900_i2c_set_time(to_i2c_client(dev), tm);
+}
+
+static int max6900_attach_adapter(struct i2c_adapter *adapter)
+{
+ return i2c_probe(adapter, &addr_data, max6900_probe);
+}
+
+static int max6900_detach_client(struct i2c_client *client)
+{
+ struct rtc_device *const rtc = i2c_get_clientdata(client);
+
+ if (rtc)
+ rtc_device_unregister(rtc);
+
+ return i2c_detach_client(client);
+}
+
+static struct i2c_driver max6900_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ },
+ .id = I2C_DRIVERID_MAX6900,
+ .attach_adapter = max6900_attach_adapter,
+ .detach_client = max6900_detach_client,
+};
+
+static const struct rtc_class_ops max6900_rtc_ops = {
+ .read_time = max6900_rtc_read_time,
+ .set_time = max6900_rtc_set_time,
+};
+
+static int max6900_probe(struct i2c_adapter *adapter, int addr, int kind)
+{
+ int rc = 0;
+ struct i2c_client *client = NULL;
+ struct rtc_device *rtc = NULL;
+
+ if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
+ rc = -ENODEV;
+ goto failout;
+ }
+
+ client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
+ if (client == NULL) {
+ rc = -ENOMEM;
+ goto failout;
+ }
+
+ client->addr = addr;
+ client->adapter = adapter;
+ client->driver = &max6900_driver;
+ strlcpy(client->name, DRV_NAME, I2C_NAME_SIZE);
+
+ if (kind < 0) {
+ rc = max6900_i2c_validate_client(client);
+ if (rc < 0)
+ goto failout;
+ }
+
+ rc = i2c_attach_client(client);
+ if (rc < 0)
+ goto failout;
+
+ dev_info(&client->dev,
+ "chip found, driver version " DRV_VERSION "\n");
+
+ rtc = rtc_device_register(max6900_driver.driver.name,
+ &client->dev,
+ &max6900_rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc)) {
+ rc = PTR_ERR(rtc);
+ goto failout_detach;
+ }
+
+ i2c_set_clientdata(client, rtc);
+
+ return 0;
+
+failout_detach:
+ i2c_detach_client(client);
+failout:
+ kfree(client);
+ return rc;
+}
+
+static int __init max6900_init(void)
+{
+ return i2c_add_driver(&max6900_driver);
+}
+
+static void __exit max6900_exit(void)
+{
+ i2c_del_driver(&max6900_driver);
+}
+
+MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(DRV_VERSION);
+
+module_init(max6900_init);
+module_exit(max6900_exit);
projects / GitHub / exynos8895 / android_kernel_samsung_universal8895.git / commitdiff