aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/rtc
diff options
context:
space:
mode:
authorTroy Kisky <troy.kisky@boundarydevices.com>2017-11-02 18:58:14 -0700
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2017-11-08 07:52:23 +0100
commit2cb90ed3de1e279dbaf23df141f54eb9fb1861e6 (patch)
treec8213cc4214ee238e1040746bc9f0495c9df7f62 /drivers/rtc
parentc8384bb04261b9d32fe7402a6068ddaf38913b23 (diff)
rtc: m41t80: avoid i2c read in m41t80_sqw_recalc_rate
This is a little more efficient, and avoids the warning WARNING: possible circular locking dependency detected 4.14.0-rc7-00007 #14 Not tainted ------------------------------------------------------ alsactl/330 is trying to acquire lock: (prepare_lock){+.+.}, at: [<c049300c>] clk_prepare_lock+0x80/0xf4 but task is already holding lock: (i2c_register_adapter){+.+.}, at: [<c0690ae0>] i2c_adapter_lock_bus+0x14/0x18 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (i2c_register_adapter){+.+.}: rt_mutex_lock+0x44/0x5c i2c_adapter_lock_bus+0x14/0x18 i2c_transfer+0xa8/0xbc i2c_smbus_xfer+0x20c/0x5d8 i2c_smbus_read_byte_data+0x38/0x48 m41t80_sqw_recalc_rate+0x24/0x58 Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/rtc-m41t80.c28
1 files changed, 17 insertions, 11 deletions
diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
index 42fc735a5446..f44dcf628c87 100644
--- a/drivers/rtc/rtc-m41t80.c
+++ b/drivers/rtc/rtc-m41t80.c
@@ -154,6 +154,7 @@ struct m41t80_data {
struct rtc_device *rtc;
#ifdef CONFIG_COMMON_CLK
struct clk_hw sqw;
+ unsigned long freq;
#endif
};
@@ -443,26 +444,28 @@ static SIMPLE_DEV_PM_OPS(m41t80_pm, m41t80_suspend, m41t80_resume);
#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)
+static unsigned long m41t80_decode_freq(int setting)
+{
+ return (setting == 0) ? 0 : (setting == 1) ? M41T80_SQW_MAX_FREQ :
+ M41T80_SQW_MAX_FREQ >> setting;
+}
+
+static unsigned long m41t80_get_freq(struct m41t80_data *m41t80)
{
- 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;
+ return m41t80_decode_freq(ret >> 4);
+}
- ret >>= 4;
- if (ret == 0)
- val = 0;
- else if (ret > 1)
- val = val / (1 << ret);
-
- return val;
+static unsigned long m41t80_sqw_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ return sqw_to_m41t80_data(hw)->freq;
}
static long m41t80_sqw_round_rate(struct clk_hw *hw, unsigned long rate,
@@ -505,6 +508,8 @@ static int m41t80_sqw_set_rate(struct clk_hw *hw, unsigned long rate,
reg = (reg & 0x0f) | (val << 4);
ret = i2c_smbus_write_byte_data(client, reg_sqw, reg);
+ if (!ret)
+ m41t80->freq = m41t80_decode_freq(val);
return ret;
}
@@ -579,6 +584,7 @@ static struct clk *m41t80_sqw_register_clk(struct m41t80_data *m41t80)
init.parent_names = NULL;
init.num_parents = 0;
m41t80->sqw.init = &init;
+ m41t80->freq = m41t80_get_freq(m41t80);
/* optional override of the clockname */
of_property_read_string(node, "clock-output-names", &init.name);

Privacy Policy