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Subject[PATCH 2/2] rtc: rtc-ds1307: add alarm support for mcp7941x chips
Date
This patch adds 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>
---
drivers/rtc/rtc-ds1307.c | 183 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 182 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 8c70b2238e88..580379a97f0c 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -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,
@@ -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,
@@ -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))
@@ -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;
}
@@ -929,7 +1110,7 @@ read_rtc:

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)) {
err = PTR_ERR(ds1307->rtc);
dev_err(&client->dev,
--
1.8.5.3


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