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authorAkinobu Mita <akinobu.mita@gmail.com>2016-01-31 15:10:10 +0100
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-03-14 17:08:13 +0100
commit6c6ff145b3346b071e7d80f9bd33aa7de0e438bc (patch)
treebdd4e8997f5b9c64ec1d00d219e0d18cd27999d8 /drivers/rtc/rtc-ds1307.c
parentrtc: max77686: move initialisation of rtc regmap, irq chip locally (diff)
downloadlinux-6c6ff145b3346b071e7d80f9bd33aa7de0e438bc.tar.xz
linux-6c6ff145b3346b071e7d80f9bd33aa7de0e438bc.zip
rtc: ds1307: add clock provider support for DS3231
DS3231 has programmable square-wave output signal. This enables to use this feature as a clock provider of common clock framework. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Michael Turquette <mturquette@baylibre.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Diffstat (limited to 'drivers/rtc/rtc-ds1307.c')
-rw-r--r--drivers/rtc/rtc-ds1307.c296
1 files changed, 295 insertions, 1 deletions
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 2462d5a53a53..b2156ee5bae1 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -21,6 +21,7 @@
#include <linux/string.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
+#include <linux/clk-provider.h>
/*
* We can't determine type by probing, but if we expect pre-Linux code
@@ -91,6 +92,7 @@ enum ds_type {
# define DS1340_BIT_OSF 0x80
#define DS1337_REG_STATUS 0x0f
# define DS1337_BIT_OSF 0x80
+# define DS3231_BIT_EN32KHZ 0x08
# define DS1337_BIT_A2I 0x02
# define DS1337_BIT_A1I 0x01
#define DS1339_REG_ALARM1_SECS 0x07
@@ -120,6 +122,9 @@ struct ds1307 {
u8 length, u8 *values);
s32 (*write_block_data)(const struct i2c_client *client, u8 command,
u8 length, const u8 *values);
+#ifdef CONFIG_COMMON_CLK
+ struct clk_hw clks[2];
+#endif
};
struct chip_desc {
@@ -926,7 +931,295 @@ static void ds1307_hwmon_register(struct ds1307 *ds1307)
{
}
-#endif
+#endif /* CONFIG_RTC_DRV_DS1307_HWMON */
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * Square-wave output support for DS3231
+ * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3231.pdf
+ */
+#ifdef CONFIG_COMMON_CLK
+
+enum {
+ DS3231_CLK_SQW = 0,
+ DS3231_CLK_32KHZ,
+};
+
+#define clk_sqw_to_ds1307(clk) \
+ container_of(clk, struct ds1307, clks[DS3231_CLK_SQW])
+#define clk_32khz_to_ds1307(clk) \
+ container_of(clk, struct ds1307, clks[DS3231_CLK_32KHZ])
+
+static int ds3231_clk_sqw_rates[] = {
+ 1,
+ 1024,
+ 4096,
+ 8192,
+};
+
+static int ds1337_write_control(struct ds1307 *ds1307, u8 mask, u8 value)
+{
+ struct i2c_client *client = ds1307->client;
+ struct mutex *lock = &ds1307->rtc->ops_lock;
+ int control;
+ int ret;
+
+ mutex_lock(lock);
+
+ control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+ if (control < 0) {
+ ret = control;
+ goto out;
+ }
+
+ control &= ~mask;
+ control |= value;
+
+ ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
+out:
+ mutex_unlock(lock);
+
+ return ret;
+}
+
+static unsigned long ds3231_clk_sqw_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
+ int control;
+ int rate_sel = 0;
+
+ control = i2c_smbus_read_byte_data(ds1307->client, DS1337_REG_CONTROL);
+ if (control < 0)
+ return control;
+ if (control & DS1337_BIT_RS1)
+ rate_sel += 1;
+ if (control & DS1337_BIT_RS2)
+ rate_sel += 2;
+
+ return ds3231_clk_sqw_rates[rate_sel];
+}
+
+static long ds3231_clk_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ int i;
+
+ for (i = ARRAY_SIZE(ds3231_clk_sqw_rates) - 1; i >= 0; i--) {
+ if (ds3231_clk_sqw_rates[i] <= rate)
+ return ds3231_clk_sqw_rates[i];
+ }
+
+ return 0;
+}
+
+static int ds3231_clk_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
+ int control = 0;
+ int rate_sel;
+
+ for (rate_sel = 0; rate_sel < ARRAY_SIZE(ds3231_clk_sqw_rates);
+ rate_sel++) {
+ if (ds3231_clk_sqw_rates[rate_sel] == rate)
+ break;
+ }
+
+ if (rate_sel == ARRAY_SIZE(ds3231_clk_sqw_rates))
+ return -EINVAL;
+
+ if (rate_sel & 1)
+ control |= DS1337_BIT_RS1;
+ if (rate_sel & 2)
+ control |= DS1337_BIT_RS2;
+
+ return ds1337_write_control(ds1307, DS1337_BIT_RS1 | DS1337_BIT_RS2,
+ control);
+}
+
+static int ds3231_clk_sqw_prepare(struct clk_hw *hw)
+{
+ struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
+
+ return ds1337_write_control(ds1307, DS1337_BIT_INTCN, 0);
+}
+
+static void ds3231_clk_sqw_unprepare(struct clk_hw *hw)
+{
+ struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
+
+ ds1337_write_control(ds1307, DS1337_BIT_INTCN, DS1337_BIT_INTCN);
+}
+
+static int ds3231_clk_sqw_is_prepared(struct clk_hw *hw)
+{
+ struct ds1307 *ds1307 = clk_sqw_to_ds1307(hw);
+ int control;
+
+ control = i2c_smbus_read_byte_data(ds1307->client, DS1337_REG_CONTROL);
+ if (control < 0)
+ return control;
+
+ return !(control & DS1337_BIT_INTCN);
+}
+
+static const struct clk_ops ds3231_clk_sqw_ops = {
+ .prepare = ds3231_clk_sqw_prepare,
+ .unprepare = ds3231_clk_sqw_unprepare,
+ .is_prepared = ds3231_clk_sqw_is_prepared,
+ .recalc_rate = ds3231_clk_sqw_recalc_rate,
+ .round_rate = ds3231_clk_sqw_round_rate,
+ .set_rate = ds3231_clk_sqw_set_rate,
+};
+
+static unsigned long ds3231_clk_32khz_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ return 32768;
+}
+
+static int ds3231_clk_32khz_control(struct ds1307 *ds1307, bool enable)
+{
+ struct i2c_client *client = ds1307->client;
+ struct mutex *lock = &ds1307->rtc->ops_lock;
+ int status;
+ int ret;
+
+ mutex_lock(lock);
+
+ status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
+ if (status < 0) {
+ ret = status;
+ goto out;
+ }
+
+ if (enable)
+ status |= DS3231_BIT_EN32KHZ;
+ else
+ status &= ~DS3231_BIT_EN32KHZ;
+
+ ret = i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, status);
+out:
+ mutex_unlock(lock);
+
+ return ret;
+}
+
+static int ds3231_clk_32khz_prepare(struct clk_hw *hw)
+{
+ struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
+
+ return ds3231_clk_32khz_control(ds1307, true);
+}
+
+static void ds3231_clk_32khz_unprepare(struct clk_hw *hw)
+{
+ struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
+
+ ds3231_clk_32khz_control(ds1307, false);
+}
+
+static int ds3231_clk_32khz_is_prepared(struct clk_hw *hw)
+{
+ struct ds1307 *ds1307 = clk_32khz_to_ds1307(hw);
+ int status;
+
+ status = i2c_smbus_read_byte_data(ds1307->client, DS1337_REG_STATUS);
+ if (status < 0)
+ return status;
+
+ return !!(status & DS3231_BIT_EN32KHZ);
+}
+
+static const struct clk_ops ds3231_clk_32khz_ops = {
+ .prepare = ds3231_clk_32khz_prepare,
+ .unprepare = ds3231_clk_32khz_unprepare,
+ .is_prepared = ds3231_clk_32khz_is_prepared,
+ .recalc_rate = ds3231_clk_32khz_recalc_rate,
+};
+
+static struct clk_init_data ds3231_clks_init[] = {
+ [DS3231_CLK_SQW] = {
+ .name = "ds3231_clk_sqw",
+ .ops = &ds3231_clk_sqw_ops,
+ .flags = CLK_IS_ROOT,
+ },
+ [DS3231_CLK_32KHZ] = {
+ .name = "ds3231_clk_32khz",
+ .ops = &ds3231_clk_32khz_ops,
+ .flags = CLK_IS_ROOT,
+ },
+};
+
+static int ds3231_clks_register(struct ds1307 *ds1307)
+{
+ struct i2c_client *client = ds1307->client;
+ struct device_node *node = client->dev.of_node;
+ struct clk_onecell_data *onecell;
+ int i;
+
+ onecell = devm_kzalloc(&client->dev, sizeof(*onecell), GFP_KERNEL);
+ if (!onecell)
+ return -ENOMEM;
+
+ onecell->clk_num = ARRAY_SIZE(ds3231_clks_init);
+ onecell->clks = devm_kcalloc(&client->dev, onecell->clk_num,
+ sizeof(onecell->clks[0]), GFP_KERNEL);
+ if (!onecell->clks)
+ return -ENOMEM;
+
+ for (i = 0; i < ARRAY_SIZE(ds3231_clks_init); i++) {
+ struct clk_init_data init = ds3231_clks_init[i];
+
+ /*
+ * Interrupt signal due to alarm conditions and square-wave
+ * output share same pin, so don't initialize both.
+ */
+ if (i == DS3231_CLK_SQW && test_bit(HAS_ALARM, &ds1307->flags))
+ continue;
+
+ /* optional override of the clockname */
+ of_property_read_string_index(node, "clock-output-names", i,
+ &init.name);
+ ds1307->clks[i].init = &init;
+
+ onecell->clks[i] = devm_clk_register(&client->dev,
+ &ds1307->clks[i]);
+ if (IS_ERR(onecell->clks[i]))
+ return PTR_ERR(onecell->clks[i]);
+ }
+
+ if (!node)
+ return 0;
+
+ of_clk_add_provider(node, of_clk_src_onecell_get, onecell);
+
+ return 0;
+}
+
+static void ds1307_clks_register(struct ds1307 *ds1307)
+{
+ int ret;
+
+ if (ds1307->type != ds_3231)
+ return;
+
+ ret = ds3231_clks_register(ds1307);
+ if (ret) {
+ dev_warn(&ds1307->client->dev,
+ "unable to register clock device %d\n", ret);
+ }
+}
+
+#else
+
+static void ds1307_clks_register(struct ds1307 *ds1307)
+{
+}
+
+#endif /* CONFIG_COMMON_CLK */
static int ds1307_probe(struct i2c_client *client,
const struct i2c_device_id *id)
@@ -1294,6 +1587,7 @@ read_rtc:
}
ds1307_hwmon_register(ds1307);
+ ds1307_clks_register(ds1307);
return 0;