diff options
| -rw-r--r-- | Documentation/devicetree/bindings/rtc/maxim,ds3231.txt | 37 | ||||
| -rw-r--r-- | drivers/rtc/rtc-ds1307.c | 296 |
2 files changed, 332 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/rtc/maxim,ds3231.txt b/Documentation/devicetree/bindings/rtc/maxim,ds3231.txt new file mode 100644 index 000000000000..ddef330d2709 --- /dev/null +++ b/Documentation/devicetree/bindings/rtc/maxim,ds3231.txt @@ -0,0 +1,37 @@ +* Maxim DS3231 Real Time Clock + +Required properties: +see: Documentation/devicetree/bindings/i2c/trivial-devices.txt + +Optional property: +- #clock-cells: Should be 1. +- clock-output-names: + overwrite the default clock names "ds3231_clk_sqw" and "ds3231_clk_32khz". + +Each clock is assigned an identifier and client nodes can use this identifier +to specify the clock which they consume. Following indices are allowed: + - 0: square-wave output on the SQW pin + - 1: square-wave output on the 32kHz pin + +- interrupts: rtc alarm/event interrupt. When this property is selected, + clock on the SQW pin cannot be used. + +Example: + +ds3231: ds3231@51 { + compatible = "maxim,ds3231"; + reg = <0x68>; + #clock-cells = <1>; +}; + +device1 { +... + clocks = <&ds3231 0>; +... +}; + +device2 { +... + clocks = <&ds3231 1>; +... +}; 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; |