diff options
| -rw-r--r-- | drivers/rtc/rtc-m41t80.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index 6145bc164162..8940e9e43ea0 100644 --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -16,6 +16,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/bcd.h> +#include <linux/clk-provider.h> #include <linux/i2c.h> #include <linux/init.h> #include <linux/kernel.h> @@ -53,6 +54,8 @@ #define M41T80_ALARM_REG_SIZE \ (M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON) +#define M41T80_SQW_MAX_FREQ 32768 + #define M41T80_SEC_ST BIT(7) /* ST: Stop Bit */ #define M41T80_ALMON_AFE BIT(7) /* AFE: AF Enable Bit */ #define M41T80_ALMON_SQWE BIT(6) /* SQWE: SQW Enable Bit */ @@ -147,7 +150,11 @@ MODULE_DEVICE_TABLE(of, m41t80_of_match); struct m41t80_data { unsigned long features; + struct i2c_client *client; struct rtc_device *rtc; +#ifdef CONFIG_COMMON_CLK + struct clk_hw sqw; +#endif }; static irqreturn_t m41t80_handle_irq(int irq, void *dev_id) @@ -455,6 +462,166 @@ static struct attribute_group attr_group = { .attrs = attrs, }; +#ifdef CONFIG_COMMON_CLK +#define sqw_to_m41t80_data(_hw) container_of(_hw, struct m41t80_data, sqw) + +static unsigned long m41t80_sqw_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw); + struct i2c_client *client = m41t80->client; + int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ? + M41T80_REG_WDAY : M41T80_REG_SQW; + int ret = i2c_smbus_read_byte_data(client, reg_sqw); + unsigned long val = M41T80_SQW_MAX_FREQ; + + if (ret < 0) + return 0; + + ret >>= 4; + if (ret == 0) + val = 0; + else if (ret > 1) + val = val / (1 << ret); + + return val; +} + +static long m41t80_sqw_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *prate) +{ + int i, freq = M41T80_SQW_MAX_FREQ; + + if (freq <= rate) + return freq; + + for (i = 2; i <= ilog2(M41T80_SQW_MAX_FREQ); i++) { + freq /= 1 << i; + if (freq <= rate) + return freq; + } + + return 0; +} + +static int m41t80_sqw_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw); + struct i2c_client *client = m41t80->client; + int reg_sqw = (m41t80->features & M41T80_FEATURE_SQ_ALT) ? + M41T80_REG_WDAY : M41T80_REG_SQW; + int reg, ret, val = 0; + + if (rate) { + if (!is_power_of_2(rate)) + return -EINVAL; + val = ilog2(rate); + if (val == ilog2(M41T80_SQW_MAX_FREQ)) + val = 1; + else if (val < (ilog2(M41T80_SQW_MAX_FREQ) - 1)) + val = ilog2(M41T80_SQW_MAX_FREQ) - val; + else + return -EINVAL; + } + + reg = i2c_smbus_read_byte_data(client, reg_sqw); + if (reg < 0) + return reg; + + reg = (reg & 0x0f) | (val << 4); + + ret = i2c_smbus_write_byte_data(client, reg_sqw, reg); + if (ret < 0) + return ret; + + return -EINVAL; +} + +static int m41t80_sqw_control(struct clk_hw *hw, bool enable) +{ + struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw); + struct i2c_client *client = m41t80->client; + int ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON); + + if (ret < 0) + return ret; + + if (enable) + ret |= M41T80_ALMON_SQWE; + else + ret &= ~M41T80_ALMON_SQWE; + + return i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, ret); +} + +static int m41t80_sqw_prepare(struct clk_hw *hw) +{ + return m41t80_sqw_control(hw, 1); +} + +static void m41t80_sqw_unprepare(struct clk_hw *hw) +{ + m41t80_sqw_control(hw, 0); +} + +static int m41t80_sqw_is_prepared(struct clk_hw *hw) +{ + struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw); + struct i2c_client *client = m41t80->client; + int ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON); + + if (ret < 0) + return ret; + + return !!(ret & M41T80_ALMON_SQWE); +} + +static const struct clk_ops m41t80_sqw_ops = { + .prepare = m41t80_sqw_prepare, + .unprepare = m41t80_sqw_unprepare, + .is_prepared = m41t80_sqw_is_prepared, + .recalc_rate = m41t80_sqw_recalc_rate, + .round_rate = m41t80_sqw_round_rate, + .set_rate = m41t80_sqw_set_rate, +}; + +static struct clk *m41t80_sqw_register_clk(struct m41t80_data *m41t80) +{ + struct i2c_client *client = m41t80->client; + struct device_node *node = client->dev.of_node; + struct clk *clk; + struct clk_init_data init; + int ret; + + /* First disable the clock */ + ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON); + if (ret < 0) + return ERR_PTR(ret); + ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, + ret & ~(M41T80_ALMON_SQWE)); + if (ret < 0) + return ERR_PTR(ret); + + init.name = "m41t80-sqw"; + init.ops = &m41t80_sqw_ops; + init.flags = 0; + init.parent_names = NULL; + init.num_parents = 0; + m41t80->sqw.init = &init; + + /* optional override of the clockname */ + of_property_read_string(node, "clock-output-names", &init.name); + + /* register the clock */ + clk = clk_register(&client->dev, &m41t80->sqw); + if (!IS_ERR(clk)) + of_clk_add_provider(node, of_clk_src_simple_get, clk); + + return clk; +} +#endif + #ifdef CONFIG_RTC_DRV_M41T80_WDT /* ***************************************************************************** @@ -772,6 +939,7 @@ static int m41t80_probe(struct i2c_client *client, if (!m41t80_data) return -ENOMEM; + m41t80_data->client = client; if (client->dev.of_node) m41t80_data->features = (unsigned long) of_device_get_match_data(&client->dev); @@ -864,6 +1032,10 @@ static int m41t80_probe(struct i2c_client *client, } } #endif +#ifdef CONFIG_COMMON_CLK + if (m41t80_data->features & M41T80_FEATURE_SQ) + m41t80_sqw_register_clk(m41t80_data); +#endif return 0; } |