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rtc: update and use the MAX6900 century byte 

We now read and write the century byte in the max6900 chip.  We probably
don't need to do so on Linux-only system, but it's necessary when the chip
is shared by another OS that uses the century byte.

Signed-off-by: Dale Farnsworth <dale@farnsworth.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dale Farnsworth 2007-07-21 04:37:57 -07:00 committed by Linus Torvalds
parent 55ff1aba94
commit 8a2601f6aa
1 changed files with 73 additions and 25 deletions
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98
drivers/rtc/rtc-max6900.c
View File

@ -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);
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;
}
/*
* 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);
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)