diff options
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-max6900.c | 96 |
1 files changed, 72 insertions, 24 deletions
diff --git a/drivers/rtc/rtc-max6900.c b/drivers/rtc/rtc-max6900.c index eee4ee5bb75a..a1cd448639c9 100644 --- a/drivers/rtc/rtc-max6900.c +++ b/drivers/rtc/rtc-max6900.c @@ -31,17 +31,24 @@ #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 + /* register 8 is undocumented */ +#define MAX6900_REG_CENTURY 9 /* century */ +#define MAX6900_REG_LEN 10 + +#define MAX6900_BURST_LEN 8 /* can burst r/w first 8 regs */ #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_CENTURY_WRITE 0x92 +#define MAX6900_REG_CENTURY_READ 0x93 #define MAX6900_REG_RESERVED_READ 0x96 +#define MAX6900_REG_BURST_WRITE 0xbe +#define MAX6900_REG_BURST_READ 0xbf #define MAX6900_IDLE_TIME_AFTER_WRITE 3 /* specification says 2.5 mS */ @@ -58,19 +65,32 @@ 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] = { + u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ }; + u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ }; + struct i2c_msg msgs[4] = { { .addr = client->addr, .flags = 0, /* write */ - .len = sizeof(reg_addr), - .buf = reg_addr + .len = sizeof(reg_burst_read), + .buf = reg_burst_read }, { .addr = client->addr, .flags = I2C_M_RD, - .len = MAX6900_REG_LEN, + .len = MAX6900_BURST_LEN, .buf = buf + }, + { + .addr = client->addr, + .flags = 0, /* write */ + .len = sizeof(reg_century_read), + .buf = reg_century_read + }, + { + .addr = client->addr, + .flags = I2C_M_RD, + .len = sizeof(buf[MAX6900_REG_CENTURY]), + .buf = &buf[MAX6900_REG_CENTURY] } }; int rc; @@ -86,33 +106,58 @@ static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf) 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] = { + u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE }; + struct i2c_msg century_msgs[1] = { { .addr = client->addr, .flags = 0, /* write */ - .len = MAX6900_REG_LEN + 1, - .buf = i2c_buf + .len = sizeof(i2c_century_buf), + .buf = i2c_century_buf + } + }; + u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE }; + struct i2c_msg burst_msgs[1] = { + { + .addr = client->addr, + .flags = 0, /* write */ + .len = sizeof(i2c_burst_buf), + .buf = i2c_burst_buf } }; int rc; - memcpy(&i2c_buf[1], buf, MAX6900_REG_LEN); + /* + * We have to make separate calls to i2c_transfer because of + * the need to delay after each write to the chip. Also, + * we write the century byte first, since we set the write-protect + * bit as part of the burst write. + */ + i2c_century_buf[1] = buf[MAX6900_REG_CENTURY]; + rc = i2c_transfer(client->adapter, century_msgs, + ARRAY_SIZE(century_msgs)); + if (rc != ARRAY_SIZE(century_msgs)) + goto write_failed; + msleep(MAX6900_IDLE_TIME_AFTER_WRITE); - 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; - } + memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN); + + rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs)); + if (rc != ARRAY_SIZE(burst_msgs)) + goto write_failed; msleep(MAX6900_IDLE_TIME_AFTER_WRITE); + return 0; + +write_failed: + dev_err(&client->dev, "%s: register write failed\n", + __FUNCTION__); + return -EIO; } static int max6900_i2c_validate_client(struct i2c_client *client) { u8 regs[MAX6900_REG_LEN]; - u8 zero_mask[MAX6900_REG_LEN] = { + u8 zero_mask[] = { 0x80, /* seconds */ 0x80, /* minutes */ 0x40, /* hours */ @@ -134,7 +179,7 @@ static int max6900_i2c_validate_client(struct i2c_client *client) if (rc < 0) return rc; - for (i = 0; i < MAX6900_REG_LEN; ++i) { + for (i = 0; i < ARRAY_SIZE(zero_mask); ++i) { if (regs[i] & zero_mask[i]) return -ENODEV; } @@ -156,7 +201,8 @@ static int max6900_i2c_read_time(struct i2c_client *client, struct rtc_time *tm) 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_year = BCD2BIN(regs[MAX6900_REG_YR]) + + BCD2BIN(regs[MAX6900_REG_CENTURY]) * 100 - 1900; tm->tm_wday = BCD2BIN(regs[MAX6900_REG_DW]); return 0; @@ -189,9 +235,11 @@ static int max6900_i2c_set_time(struct i2c_client *client, 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 */ + regs[MAX6900_REG_YR] = BIN2BCD(tm->tm_year % 100); + regs[MAX6900_REG_CENTURY] = BIN2BCD((tm->tm_year + 1900) / 100); + /* set write protect */ + regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP; rc = max6900_i2c_write_regs(client, regs); if (rc < 0) |