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drivers/rtc/rtc-ds1307.c: add alarm support for mcp7941x chips
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Add alarm support for the Microchip RTC devices MCP794xx.  Note that two
programmable alarms are provided by the chip but only one is used by the
driver.

Signed-off-by: Simon Guinot <simon.guinot@sequanux.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Gregory Clement <gregory.clement@free-electrons.com>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Simon Guinot authored and Linus Torvalds committed Apr 3, 2014
1 parent 5ea7351 commit 1d1945d
Showing 1 changed file with 182 additions and 1 deletion.
183 changes: 182 additions & 1 deletion drivers/rtc/rtc-ds1307.c
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Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,7 @@ static const struct chip_desc chips[last_ds_type] = {
.alarm = 1,
},
[mcp7941x] = {
.alarm = 1,
/* this is battery backed SRAM */
.nvram_offset = 0x20,
.nvram_size = 0x40,
Expand Down Expand Up @@ -606,6 +607,178 @@ static const struct rtc_class_ops ds13xx_rtc_ops = {

/*----------------------------------------------------------------------*/

/*
* Alarm support for mcp7941x devices.
*/

#define MCP7941X_REG_CONTROL 0x07
# define MCP7941X_BIT_ALM0_EN 0x10
# define MCP7941X_BIT_ALM1_EN 0x20
#define MCP7941X_REG_ALARM0_BASE 0x0a
#define MCP7941X_REG_ALARM0_CTRL 0x0d
#define MCP7941X_REG_ALARM1_BASE 0x11
#define MCP7941X_REG_ALARM1_CTRL 0x14
# define MCP7941X_BIT_ALMX_IF (1 << 3)
# define MCP7941X_BIT_ALMX_C0 (1 << 4)
# define MCP7941X_BIT_ALMX_C1 (1 << 5)
# define MCP7941X_BIT_ALMX_C2 (1 << 6)
# define MCP7941X_BIT_ALMX_POL (1 << 7)
# define MCP7941X_MSK_ALMX_MATCH (MCP7941X_BIT_ALMX_C0 | \
MCP7941X_BIT_ALMX_C1 | \
MCP7941X_BIT_ALMX_C2)

static void mcp7941x_work(struct work_struct *work)
{
struct ds1307 *ds1307 = container_of(work, struct ds1307, work);
struct i2c_client *client = ds1307->client;
int reg, ret;

mutex_lock(&ds1307->rtc->ops_lock);

/* Check and clear alarm 0 interrupt flag. */
reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_ALARM0_CTRL);
if (reg < 0)
goto out;
if (!(reg & MCP7941X_BIT_ALMX_IF))
goto out;
reg &= ~MCP7941X_BIT_ALMX_IF;
ret = i2c_smbus_write_byte_data(client, MCP7941X_REG_ALARM0_CTRL, reg);
if (ret < 0)
goto out;

/* Disable alarm 0. */
reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_CONTROL);
if (reg < 0)
goto out;
reg &= ~MCP7941X_BIT_ALM0_EN;
ret = i2c_smbus_write_byte_data(client, MCP7941X_REG_CONTROL, reg);
if (ret < 0)
goto out;

rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);

out:
if (test_bit(HAS_ALARM, &ds1307->flags))
enable_irq(client->irq);
mutex_unlock(&ds1307->rtc->ops_lock);
}

static int mcp7941x_read_alarm(struct device *dev, struct rtc_wkalrm *t)
{
struct i2c_client *client = to_i2c_client(dev);
struct ds1307 *ds1307 = i2c_get_clientdata(client);
u8 *regs = ds1307->regs;
int ret;

if (!test_bit(HAS_ALARM, &ds1307->flags))
return -EINVAL;

/* Read control and alarm 0 registers. */
ret = ds1307->read_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
if (ret < 0)
return ret;

t->enabled = !!(regs[0] & MCP7941X_BIT_ALM0_EN);

/* Report alarm 0 time assuming 24-hour and day-of-month modes. */
t->time.tm_sec = bcd2bin(ds1307->regs[3] & 0x7f);
t->time.tm_min = bcd2bin(ds1307->regs[4] & 0x7f);
t->time.tm_hour = bcd2bin(ds1307->regs[5] & 0x3f);
t->time.tm_wday = bcd2bin(ds1307->regs[6] & 0x7) - 1;
t->time.tm_mday = bcd2bin(ds1307->regs[7] & 0x3f);
t->time.tm_mon = bcd2bin(ds1307->regs[8] & 0x1f) - 1;
t->time.tm_year = -1;
t->time.tm_yday = -1;
t->time.tm_isdst = -1;

dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
"enabled=%d polarity=%d irq=%d match=%d\n", __func__,
t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
t->time.tm_wday, t->time.tm_mday, t->time.tm_mon, t->enabled,
!!(ds1307->regs[6] & MCP7941X_BIT_ALMX_POL),
!!(ds1307->regs[6] & MCP7941X_BIT_ALMX_IF),
(ds1307->regs[6] & MCP7941X_MSK_ALMX_MATCH) >> 4);

return 0;
}

static int mcp7941x_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
struct i2c_client *client = to_i2c_client(dev);
struct ds1307 *ds1307 = i2c_get_clientdata(client);
unsigned char *regs = ds1307->regs;
int ret;

if (!test_bit(HAS_ALARM, &ds1307->flags))
return -EINVAL;

dev_dbg(dev, "%s, sec=%d min=%d hour=%d wday=%d mday=%d mon=%d "
"enabled=%d pending=%d\n", __func__,
t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
t->time.tm_wday, t->time.tm_mday, t->time.tm_mon,
t->enabled, t->pending);

/* Read control and alarm 0 registers. */
ret = ds1307->read_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
if (ret < 0)
return ret;

/* Set alarm 0, using 24-hour and day-of-month modes. */
regs[3] = bin2bcd(t->time.tm_sec);
regs[4] = bin2bcd(t->time.tm_min);
regs[5] = bin2bcd(t->time.tm_hour);
regs[6] = bin2bcd(t->time.tm_wday) + 1;
regs[7] = bin2bcd(t->time.tm_mday);
regs[8] = bin2bcd(t->time.tm_mon) + 1;

/* Clear the alarm 0 interrupt flag. */
regs[6] &= ~MCP7941X_BIT_ALMX_IF;
/* Set alarm match: second, minute, hour, day, date, month. */
regs[6] |= MCP7941X_MSK_ALMX_MATCH;

if (t->enabled)
regs[0] |= MCP7941X_BIT_ALM0_EN;
else
regs[0] &= ~MCP7941X_BIT_ALM0_EN;

ret = ds1307->write_block_data(client, MCP7941X_REG_CONTROL, 10, regs);
if (ret < 0)
return ret;

return 0;
}

static int mcp7941x_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct i2c_client *client = to_i2c_client(dev);
struct ds1307 *ds1307 = i2c_get_clientdata(client);
int reg;

if (!test_bit(HAS_ALARM, &ds1307->flags))
return -EINVAL;

reg = i2c_smbus_read_byte_data(client, MCP7941X_REG_CONTROL);
if (reg < 0)
return reg;

if (enabled)
reg |= MCP7941X_BIT_ALM0_EN;
else
reg &= ~MCP7941X_BIT_ALM0_EN;

return i2c_smbus_write_byte_data(client, MCP7941X_REG_CONTROL, reg);
}

static const struct rtc_class_ops mcp7941x_rtc_ops = {
.read_time = ds1307_get_time,
.set_time = ds1307_set_time,
.read_alarm = mcp7941x_read_alarm,
.set_alarm = mcp7941x_set_alarm,
.alarm_irq_enable = mcp7941x_alarm_irq_enable,
};

/*----------------------------------------------------------------------*/

static ssize_t
ds1307_nvram_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
Expand Down Expand Up @@ -678,6 +851,7 @@ static int ds1307_probe(struct i2c_client *client,
[ds_1339] = DS1339_BIT_BBSQI,
[ds_3231] = DS3231_BIT_BBSQW,
};
const struct rtc_class_ops *rtc_ops = &ds13xx_rtc_ops;

if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
&& !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
Expand Down Expand Up @@ -816,6 +990,13 @@ static int ds1307_probe(struct i2c_client *client,
case ds_1388:
ds1307->offset = 1; /* Seconds starts at 1 */
break;
case mcp7941x:
rtc_ops = &mcp7941x_rtc_ops;
if (ds1307->client->irq > 0 && chip->alarm) {
INIT_WORK(&ds1307->work, mcp7941x_work);
want_irq = true;
}
break;
default:
break;
}
Expand Down Expand Up @@ -929,7 +1110,7 @@ static int ds1307_probe(struct i2c_client *client,

device_set_wakeup_capable(&client->dev, want_irq);
ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
&ds13xx_rtc_ops, THIS_MODULE);
rtc_ops, THIS_MODULE);
if (IS_ERR(ds1307->rtc)) {
return PTR_ERR(ds1307->rtc);
}
Expand Down

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